(The) relationship between the daily habits of parents of students and children's dental caries

역학및건강증진학과/석사[한글] 본 연구는 학부모들의 생활습관과 자녀들의 치아우식증과의 관련성을 파악하기 위하여 2004년 3월 12일부터 3월 27일 까지 직접 구강검진과 설문지를 이용하여 실시하였다. 연구 대상은 경기도 일 지역의 초등학교에서 이 학교에 다니는 학동들을 자녀로 둔, 중 정도의 생활수준을 가진 학부모와 그 자녀들(1-6학년) 993명(남: 499명, 여: 494명)이며, 연구의 결과는 다음과 같다. 학부모의 구강건강관리 습관과 아동의 치아우식증의 관련성은 아버지에서는 저학년의 아버지의 결손치아(OR=1.91)와 양치시간(OR=2.28)에서 관련이 있었고, 고학년에서는 아버지의 치과치료 경험(OR=0.37)과 관련이 있었다. 반면에 어머니에서는, 저학년의 어머니의 양치시간(OR=2.07)과 고학년의 어머니의 결손치아(OR=2.86)와 관련이 있었다. 학부모의 아동 치아에 대한 관심도와 아동의 치아우식증의 관련성은 저학년에서 아버지의 아동 치아에 대한 관심도(OR=2.03)가 관련이 있는 반면에 어머니에서는 관련이 없었다. 이상의 연구를 종합하여 볼 때, 학부모의 생활습관은 아동의 치아우식증에 부분적으로 관련이 있음을 알 수 있었고 특히, 어머니 뿐 만아니라 아버지의 구강건강관리 습관도 아동의 치아우식에 영향을 미칠 수 있음을 암시 하였다. [영문]This research was conducted based on my personal dental examinations and questionnaires examined and executed from March 12th to March 27th, 2004, in order to thoroughly grasp of the relationship between the daily habits of the parents and their children''s dental caries. The subjects of this study were based on 993 elementary students. Accurately, there were 499 boys and 494 girls from first to sixth grades in Kyoungi province area based on the existence of both parents and in the middle standard of living. The results of the study were as follows. Results : The relationship between the daily habits of dental cares in the parents and their children''s dental caries were affected by the father''s functionally missing teeth(OR=1.91) and the hours of brushing teeth(OR=2.28) with the lower grades and father''s experience of dental treatment(OR=0.37) with the higher grades. On the other hand, the relationship was the opposite with the mother''s hours of brushing teeth (OR=2.07)with the lower grades and mother''s functionally missing teeth(OR=2.86) with higher grades. The relationship between the parent''s interest in their children''s teeth and dental caries(OR=2.03) were related with fathers only in the lower graders. On the other hand, no connection was made with mothers. Conclusion : Synthesizing the research mentioned above, the results acknowledge that the parent''s daily habits was partially associated with the children''s dental caries. Especially, the results indicate that the children''s dental caries were influenced by the daily habits of dental cares in mothers as well as fathers.ope

우리나라 의약품 표준소매가격제도에 관한 연구

학위논문(석사)--서울대학교 보건대학원 :보건학과 보건경제전공,1997.Maste

-2012-2018년 현지지도 동행자를 중심으로-

학위논문(석사)--서울대학교 대학원 :행정대학원 행정학과,2020. 2. 임도빈.There were many concerns about the collapse of the North Korean regime right after North Korean leader Kim Jong Un's third hereditary power succession, but eight years later, the Kim Jong Un regime remains unchanged. Although this can be interpreted as a result of the effective operation of the Kim Jong-Un regime, it is also true that the political situation of the Kim Jong-Un regime cannot be asserted as it is difficult to grasp the internal political situation due to its closed and isolated political system. However, assessing the stability of the Kim Jong-Un regime, both in terms of inter-Korean economic cooperation and in terms of giving up North Korea's nuclear weapons program, is essential as a basis for the unification policy. According to the theory of autocracy, politics is impossible to govern by one ruler in any political system. That's why in order to assess the autocratic political system, it is necessary to analyze the network of the power elite of Kim Jong-un's regime, rather than simply targeting the leadership of Kim Jong-un. This research will analyze the characteristics and change of the network through analysis of social networks with data from field guidance of the Kim Jong-Un regime. And we want to apply the analysis results to the theory of autocratic politics to look at Kim Jong-un's rule over North Korea's power elite. And through the analysis, I would like to discuss the stability of the Kim Jong Un dictatorship that currently governs North Korea. Analysts have found evidence that the Kim Jong-un regime's winning coalition is reduced and be reorganized. And this can be interpreted as a basis for showing the stability of Kim Jong-un's dictatorship, according to his autocratic political theory.김정은 국무위원장의 북한정권 3대 세습 직후, 북한 정권의 붕괴에 대한 우려가 많았지만 8년이 지난 현재 김정은 정권은 변함없이 유지되고 있다. 이는 결과적으로는 김정은 정권의 통치술이 유효하게 작동한 것으로 평가할 수 있지만, 폐쇄적이고 고립적인 정치체제인 북한정체의 특성상 내부의 정치상황을 파악하기 힘들어 정권의 안정을 단언할 수는 없는 것도 현실이다. 하지만 남북경제협력의 측면에서나 북핵포기의 측면에서나 김정은 정권의 안정성을 평가하는 것은 통일정책의 근거로서 반드시 필요하다. 독재정치 이론에 따르면 정치는 어떠한 정치체제에서도 통치자 1인에 의한 통치는 불가능하다. 그렇기 때문에 독재정치 체제를 평가하기 위해서는 단순히 김정은 위원장을 대상으로 분석하는 것이 아니라 그 측근의 권력 엘리트들의 네트워크를 분석할 필요가 있다. 본 연구는 김정은 정권의 권력엘리트 네트워크를 대상으로 현지지도 수행자를 자료로 사회 네트워크 분석을 통해 네트워크의 특성과 변동을 분석하고자 한다. 그리고 분석한 결과를 독재정치 이론에 적용하여 김정은 위원장의 북한 권력엘리트에 대한 통제를 살펴보고자 한다. 그리고 분석결과를 통해서 현재 북한을 통치하는 김정은 독재정권의 안정성에 대해서 논하고자 한다. 분석결과, 김정은 정권의 승자연합은 축소되고 개편되고 있으며, 독자적으로 집단화되지 않았다는 근거를 찾아낼 수 있었다. 또 그리고 이를 독재정치 이론에 적용하면 김정은 위원장이 권력 엘리트에게 통제력을 가지고 있다고 볼 수 있다. 이는 김정은 정권의 안정성을 보여주는 하나의 근거로 해석될 수 있다.제 1 장 연구의 목적 1 제 1 절 연구의 필요성 1 제 2 장 이론적 논의와 선행연구 검토 5 제 1 절 이론적논의 5 1. 권력 엘리트의 개념 5 2. 엘리트 이론 6 3. 독재정치 이론 8 4. 현지지도 14 제 2 절 선행연구의 검토 18 1. 독재정치 이론을 적용한 선행연구 18 2. 북한 권력엘리트의 양적자료를 분석한 선행연구 21 3. 선행연구의 정리 23 4. 선행연구의 공백 27 제 3 장 연구 설계 및 연구방법 30 제 1 절 연구문제 30 제 2 절 연구의 대상과 범위 35 1. 북한 권력엘리트와 현지지도 수행자 네트워크 35 2. 연구의 시간적 범위 36 제 3 절 연구방법 37 1. 소셜네크워크 분석 37 2. 중심성 분석 39 3. 동종선호검정 45 4. 모듈러리티에 기반한 커뮤니티 분석 46 제 4 장 분석결과 48 제 1 절 네트워크의 특성 47 제 2 절 현지지도 네트워크 규모 분석결과 49 제 3 절 중심성 분석결과 50 제 4 절 동종선호성 검정결과 54 1. 김정은 집권과도기 현지지도 네트워크 54 2. 김정은 집권안정기 현지지도 네트워크 56 제 5 절 모듈러리티에 기반한 커뮤니티 분석결과 58 1. 김정은 정권의 군부대 현지지도 네트워크 커뮤니티 분석 58 2. 김정은 정권의 경제·행정분야 현지지도 네트워크 커뮤니티 분석 62 제 5 장 결과 68 제 1 절 연구의 요약 68 제 2 절 연구의 의의 69 제 3 절 연구의 한계 및 연구과제 70 참고문헌 73 Abstract 78Maste

Pre-service chemistry teachers' understanding of the potential energy curve

In this study, the pre-service chemistry teachers' understanding of potential energy curve was investigated. The subjects were 24 junior students and 26 senior students studying chemistry education in a college of education. A concept questionnaire consisted of thought experiments with different initial conditions was developed to survey the pre-service teachers' conceptions of potential energy curve. The survey results showed that the pre-service chemistry teachers had difficulties to accept the negative values for potential energy and total energy. And they knew the mechanical energy conservation but they could not apply it properly to the thought experiment situations given in the questionnaire. Also they had the knowledge about the direction of force exerted between the two balls, but many of them believed that the balls would stop moving at the bottom of potential energy curve well. In addition, it was discovered that few pre-service teachers could relate the thought experiments to the chemical bonding, the liquefaction of gas, and the molecular vibration

Identification of high school students' understanding on the reaction rate change during chemical equilibrium shift

The purpose of this study is to investigate the students' conceptions about the reaction rate changes during the chemical equilibrium shifts and also whether the questions about basic concepts of the reaction rate are helpful for the students' understanding of reaction rate changes during the chemical equilibrium shifts. The subjects were 100 students in the 12th grade. The questionnaires were composed of A, B, and A' set, which had to be answered sequentially. The A set consisted of questions asking the change of reaction rate when chemical equilibrium was shifted, the B set was to testify the basic concepts of the reaction rate, and the A' set was the same as the A set. The results showed that the students' understanding of the reverse reaction rate change was lower than that of the forward reaction rate change during the equilibrium shift. Also it was found that students' understanding of the reaction rate change caused by adding the reactant was fairly good while their understanding of the reaction rate change caused by temperature increment was very poor. Since the students marked very high scores in the B set questions, their poor understanding for the reaction rate changes during the equilibriurn shifts was not seemed to be due to the lacks of the basic knowledge of reaction rate. Instead, it was due to the failure of applying the basic knowledge of reaction rate to the changes of reaction conditions. It was also found that the average scores of A' set were statistically higher than those of A set. It means the B set items were helpful for the students to solve the A' set items. These results evidenced the possibility of set questionnaires could help the students to connect the related concepts in solving the problems

TIPS 프로그램 사례를 중심으로

학위논문(박사) -- 서울대학교대학원 : 행정대학원 행정학과, 2024. 2. 임도빈.본 연구는 대한민국 중소벤처기업부의 창업지원정책인 TIPS 프 로그램을 사례로 하여 정부가 창업지원정책의 새로운 정책행위자 인 스타트업 액셀러레이터(이하 액셀러레이터)와 이를 활용한 정책 의 변동을 설명하고자 하고 TIPS 프로그램의 변동이 정책성과에 미치는 영향에 대해서 관찰하고 있다. TIPS 프로그램은 창업생태계의 활성화라는 정책목표 달성을 위 해 액셀러레이터를 새로운 정책행위자로 활용하는 정책사업으로, 이스라엘의 T.I. 프로그램을 벤치마킹해 만들어졌다. TIPS 프로그램 은 1억원 이상 선행투자한 창업기업에 한해 민간 액셀러레이터가 R&D 보조금 수혜대상으로 추천하고 TIPS 프로그램에 선발된 창업 기업에 대한 창업보육과 후속투자 유치라는 업무를 담당하도록 하 는 프로그램이다. TIPS 프로그램의 시범사업기 동안, 액셀러레이터들은 지속적으 로 액셀러레이터의 법제화와 그에 따른 권한을 정부에 요구했고. 정부도 정책학습을 통해 액셀러레이터의 법제화를 추진하였다. 이 와중에 유명 액셀러레이터이자 TIPS 프로그램 운영사인 더벤처스 의 호창성 대표의 구속 사태가 일어났다. 더벤처스의 호창성 대표 는 TIPS 프로그램 선발시 받을 수 있는 R&D 지원금을 액셀러레이 터의 창업기업 지분투자에 산정한 것이다. 이런 문제점에 봉착한 정부는 액셀러레이터 법제화를 추진하였고 「TIPS 선진화 방안」 에는 지원보다는 규제적 성격의 정책수단을 추가하였다. 더불어 TIPS 프로그램의 정책변동이 일어난다. TIPS 프로그램 정식사업기에는액셀러레이터의 관리 및 육성 이라는 새로운 사업목표에 따라 기존의 지원정책집행기관이었던 액셀러레이터는 사실상 규제대상기관으로 전환되었다. TIPS 프로 그램의 정식사업기에는 기존의 보조금 정책과 더불어 조세지출이 라는 지원적 정책수단이 추가되었지만, 이제 진입규제, 경제규제, 정보공개라는 규제적 정책수단이 동시에 시행하게 된 것이다. 그 리고 액셀러레이터에게 위임한 창업기업 추천권한을 일부회수했으 며 성과평가에 기반한 추천권 및 운영지원자금의 차등분배로 인해 규제적 성격이 강해졌다. 이런 정책변동으로 인해 지원적 정책수단과 규제적 정책수단간 의 정책수단 조합의 비일관성이 나타나고, 그로인해 액셀러레이터 의 인센티브에도 변화가 발생하였다. 기존의 액셀러레이터들이 정 부에 액셀러레이터로 등록을 하지 않는 등의 저항을 하거나, 새로 운 액셀러레이터들이 적극적으로 정부에 액셀러레이터로 등록하면 서 정책에 순응하는 반응을 보이는 것이 전형적인 예이다. 그럼에도 불구하고 TIPS 프로그램의 투자성과, 고용성과, 창업 기업의 생존율은 모두 지속적으로 증가함으로써 TIPS 프로그램의 정책변동은 TIPS 프로그램의 성과에는 악영향을 미치지 않은 것으 로 평가해 볼 수 있다. 또한, 액셀러레이터 등록제에도 불구하고 액셀러레이터의 지속적인 양적팽창을 가져왔지만 질적성장에는 한 계가 있었다. 본 연구는 TIPS 프로그램 사례를 통해, 창업지원정책에서 정책 행위자로서 액셀레이터와 정책집행기관에서 정책대상자가 되는 정 책변동의 과정을 설명하였다. 나아가 액셀러레이터에 대한 규제적 정책수단의 추가로 인한 비일관적 정책수단조합이 액셀러레이터의 인센티브와 정책반응에 미치는 영향을 알 수 있었다. 그리고 다양 한 민간 정책행위자가 참여사는 거버넌스 기반의 정책의 변동에 대한 지식을 확장할 수 있었다. 본 연구의 정책적 함의는 다음과 같다. 먼저 정책에서 액셀러 레이터와 같은 민간 정책집행자를 활용하기 위해서는 적절한 권한 위임과 더불어 정책대상자와의 목적함수를 일치시켜야 한다는 것 이다. 본 연구의 시간적 한계와 자료의 한계로 인해서 액셀러레이터들 의 보이콧 사태의 요인과 과정, 그리고 결과를 명확하게 확인하지 못했다. 액셀러레이터와 창업기업 같은 정책행위자의 참여동기를 파악이 중요하나 주로 2차 자료에 의존하여 연구 자료의 신뢰성을 확보하지 못했다. 정책변동의 결과에영향을 끼칠 수 있는 외재변 수를 충분히 통제하지 못했다. 주요어 : 창업지원정책, 스타트업 액셀러레이터, 창업기획자, 창업기 업, 스타트업, 정책설계, 정책수단조합 학 번 : 2020-34357This study examines the TIPS program, a startup support policy initiative by the Ministry of SMEs and Startups in the Republic of Korea, as a case study to explain the government's adoption of startup accelerators (hereafter referred to as accelerators) as new policy actors and the implications of utilizing such actors in policy shifts. It observes the impact of changes within the TIPS program on policy outcomes. The TIPS program was designed by benchmarking Israel's T.I. program and aims to activate the entrepreneurship ecosystem by incorporating accelerators as new policy actors. It is a policy project that recommends startups with over 100 million won in prior investment by private accelerators for R&D grant eligibility and manages startup incubation and follow-up investment attraction for those selected under the TIPS program. During the pilot phase of the TIPS program, accelerators consistently demanded the formalization of their role and associated rights from the government. The government, through policy learning, pushed forward the legalization of accelerators. Amidst this, Ho Chang-seong, a prominent accelerator and operator of the TIPS program from The Ventures, was detained due to allocating R&D support funds for equity investment in startups. Faced with these issues, the government pursued the formalization of accelerators and introduced more regulatory measures than supportive ones in the "TIPS Advancement Plan," leading to policy changes within the TIPS program. In the official phase of the TIPS program, the original support policy enforcement agency, the accelerator, essentially became a regulated entity. The program saw the addition of tax expenditures as a supportive policy tool alongside existing grant policies. However, entry regulations, economic regulations, and information disclosure became simultaneously enforced regulatory policy tools. The program also partially retracted the recommendation authority delegated to accelerators and introduced a more regulated nature through performance-based recommendation rights and differential distribution of operational support funds. These policy changes resulted in inconsistency in the combination of supportive and regulatory policy tools, affecting accelerators' incentives. Typical responses include resistance from existing accelerators, such as not registering with the government, and new accelerators actively registering, showing compliance with the policy. Despite these changes, the TIPS program's investment outcomes, employment outcomes, and the survival rate of startups have continuously increased, suggesting that the policy changes did not negatively impact the program's performance. However, while the registration system for accelerators led to their quantitative expansion, it also revealed limitations in qualitative growth. This study elucidates the process of policy change from accelerators acting as policy agents in entrepreneurship support policies to becoming subjects of policy through the case of the TIPS program. It further explores the impact of inconsistent policy tool combinations due to the addition of regulatory measures on accelerators' incentives and policy responses, extending knowledge on policy changes in governance-based participation of various private policy actors. The policy implications of this research highlight the importance of aligning the objective functions between policy subjects and private policy executors like accelerators, necessitating appropriate delegation of authority. The study acknowledges its temporal and data limitations, noting the inability to precisely ascertain the factors, processes, and outcomes of the accelerators' boycott. Understanding the motivations of policy actors such as accelerators and startups is crucial, yet the study primarily relied on secondary data, limiting the reliability of its research materials. It also notes the insufficient control of external variables that could affect the outcomes of policy changes.제 1 장 서론 ································································· 1 제 1 절 연구 배경 및 목적 ················································· 1 제 2 절 연구범위 및 방법 ··················································· 2 1. 연구범위 ··························································································· 2 2. 연구방법 ·························································································· 3 제 2 장 이론적 검토 ··················································· 5 제 1 절 정책변동 ··································································· 5 1. 정책변동 개념 ················································································· 5 2. 정책변동 분류 ················································································ 6 3. 정책학습 ···························································································· 8 제 2 절 정책목표 및 정책수단 ·········································· 10 1. 정책목표 ·························································································· 10 2. 정책수단의 개념과 유형분류 ························································ 11 3. 정책수단의 선택 ·············································································· 13 4. 정책수단의 종류와 성격 ································································ 17 5. 정책수단조합 ···················································································· 21 제 3 절 연구질문 ··································································· 27 제 3 장 정책행위자 ··················································· 30 제 1 절 창업생태계 ······························································· 30 1. 창업생태계 개념 ·············································································· 30 2. 정부의 창업생태계 조성 ································································ 31 제 2 절 창업기업 ··································································· 32 1. 창업기업 ···························································································· 32 2. 기술창업기업 ···················································································· 33 제 3 절 스타트업 액셀러레이터 ······································ 35 1. 스타트업 액셀러레이터의 개념 ····················································· 35 2. 액셀러레이터의 역할 ······································································ 38 제 4 절 창업지원정책 ··························································· 41 1. 창업지원정책 개념과 지원내용 ······················································ 41 2. 창업지원정책 행위자 ········································································ 42 제 4 장 TIPS 프로그램 사례 ································· 45 제 1절 TIPS 프로그램 ························································· 45 1. TIPS 프로그램의 개요 ··································································· 45 2. TIPS 프로그램의 정책설계구조 ··················································· 47 3. TIPS 프로그램의 성과 ··································································· 49 4. TIPS 프로그램의 확산 ································································· 57 제 2 절 분석대상 사례 선정 ·············································· 65 1. 분석대상 사례 선정 ······································································· 65 2. 자료 ···································································································· 66 3. 분석방법 ···························································································· 70 제 5 장 사례 분석결과 ············································· 73 제 1 절 시범사업기 ···················································· 73 1. 시범사업기의 정책과정 ···································································· 73 2. 시범사업기의 정책목표와 정책수단 ············································ 78 3. 시범사업기의 정책행위자 인센티브 ·············································· 83 4. 정책반응 ······························································································ 90 제 2 절 정식사업기 ······························································· 92 1. 정식사업기의 정책과정 ···································································· 92 2. 정식사업기의 정책목표와 정책수단 ············································ 105 3. 정식사업기의 정책행위자 인센티브 ·············································· 114 4. 정책반응 ······························································································ 121 제 3 절 정책변동의 결과 ····················································· 124 1. TIPS 프로그램 성과 ········································································· 124 2. 액셀러레이터 산업의 변화 ······························································ 132 제 6 장 결론 ····························································· 137 제 1 절 연구의 요약 ··························································· 137 제 2 절 연구의 함의 및 한계 ·········································· 140 참고문헌 ········································································ 143 Abstract ········································································ 167박

VEST 장치에서의 3D 자기 플럭스 로프를 활용한 비유도적 전류 구동 연구

학위논문(박사) -- 서울대학교대학원 : 공과대학 에너지시스템공학부, 2022. 8. 황용석.Tokamak 구조에서 magnetic helicity의 물리량은 Poloidal과 Toroidal flux의 꼬임(linkage) 정도로 정의된다. 고정 Toroidal flux 조건 및 Tokamak 구조에서 Magnetic Helicity의 증가는 Toroidal 플라즈마 전류 및 성능 증가를 의미한다. Magnetic Helicity를 주입하기 위해, 3D 구조의 Magnetic flux 로프들을 활용한 국부 정전 헬리시티 주입 방법(Local helicity injection, LHI)이 개발되었다. 이 LHI는 본질적으로 한정된 유도적 (inductive) 전류 구동(current-drive) 성능을 가진 구형 토러스 (Spherical Torus, ST)의 시동(Startup) 및 전류 구동을 위해 사용된다. ST의 시동을 위해 LHI를 사용하기 위해서는, 닫힌 플럭스 면(Closed-flux-surface, CFS)의 초기 플라즈마 생성이 필요하다. 이 초기 플라즈마에 Magnetic helicity를 주입함으로써 더욱 큰 전류가 구동될 수 있으며, 이 과정은 테일러 완화 과정(Taylor relaxation process) 으로 설명 될 수 있다. 테일러 완화 과정은 국부(local)적으로 주입된 Helicity가 전체(Global) helicity 및 전류 양으로 변화하는 과정을 뜻한다. 마침내 Tokamak과 유사한 닫힌 플럭스 면을 가지는 플라즈마가 방전된다. 여기서 중요한 점은 닫힌 플럭스 면의 초기 플라즈마 형성 없이는 구형 토러스의 시동 법으로써 국부 정전 헬리시티 주입법은 불가능 하다는 것 이다. 닫힌 플럭스 면의 초기 플라즈마를 형성할 수 있는 자기유체역학 불안정성(MHD instability) 중 하나는 3D Helical 구조에서 꼬임 불안정성(Kink instability)을 겪는 Flux 로프들의 결합(Merging)이다. 하지만 ST에서 3D 자기 Flux 로프를 활용하여 닫힌 플럭스 면의 초기 플라즈마 형성을 위한 운전 조건이 제시되거나 알려지지 않은 채로 남겨져 있고, 이는 ST 운전 실패의 가능성을 남겨두고 있다. 따라서 국부 자기 헬리시티 주입을 통한 구형 토러스 시동 성공을 위해, 3D 구조의 자기 Flux 로프들로 Tokamak과 같은 구조의 플라즈마를 형성하는 자기 위상(Magnetic Topology) 변화를 설명하기위한 물리학적 배경을 이해 및 운전 조건을 제시하는 것이 중요하게 되었다. 이러한 배경으로 이 학위 논문의 목적은, 성공적인 LHI 운전 및 ST의 시동을 위해, 3D Flux rope들로부터 닫힌 플럭스 면의 초기 플라즈마 형성을 위해 어떤 물리학적 배경이 있으며, 이들이 어떤 방식으로 연결될 수 있는지 해답을 찾고, 주어진 ST 운전 범위 안에서 물리학적 배경의 실험 운전 조건을 제시하는 것이다. VEST 장치에서 3D 구조의 플럭스 로프를 형성하기 위해, 아크 플라즈마 총과 두 개의 펄스 파워로 이루어진 LHI 시스템이 개발되었고, 성공적으로 운전되고 있다. 방전 조건에 따라 아크 플라즈마 총들은 1.5MW의 전력 범위 안에서 최대 3 kA의 플럭스 로프를 10ms 동안 방전할 수 있다. 정규화 된 유효 토로이달 일주 전압은 최소 1.4 에서 최대 2.4 V-m의 범위를 가진다. 이온 도플러 분광기(IDS)을 활용해 이온 온도를 측정할 수 있으며, 이 논문에서는 자기 재결합 현상의 정도를 대변하기 위해 사용되었다. 주요 분광 선은 CIII(464.7 nm)로, VEST에서 가장 강한 불순물 성분이다. 본격적인 플럭스 로프들 사이 결합(merging) 현상 연구전에, 아크 플라즈마 총으로부터 방전된 3D 플럭스 로프들의 두 가지 꼬임 불안정성 모드에 대해 관찰하고 분석하였다. 이 모든 상태는 어떠한 물리적 침범 없이, IDS와 자기 진단계를 활용하여 진단되었다. 축 방향 자기장 세기를 주요 변수로 하여, 이를 통해 플럭스 로프들의 안정 상태를 제어할 수 있었다. 이 자기장 세기가 플럭스 로프로부터 생성된 Poloidal Field보다 강할 때는, 플럭스 로프는 %안정상태(MHD stable)에 있으며, 이 플라즈마의 온도와 밀도는 배경 중성 가스 입자에 의해 결정 된다. 축 방향 자기장 세기가 낮아짐에 따라, 내부 결맞음 꼬임 불안정성(Internal coherent kink instability)이 나타나며, 꼬임 불안정성의 회전 주파수 및 변형(deformation) 정도가 계산되었으며, 실험과 계산 결과가 매우 잘 맞는 결과를 보여주었다. 현상학적(Phenomenological) 꼬임 불안정성 이론과 단일 에너지(Monoenergetic) 가정을 기본으로 한 결맞음(Coherent) 회전 모델이 개발되었고, 이 결과와 실험 결과 역시 매우 잘 일치하는 결과를 보여주었다. 축 방향 자기장 성분을 더 감소시키면, 더욱 불안정한 외부 꼬임 불안정성(Highly unstable external kink instability)이 관찰되며, 자기 진단계에 혼돈 행태 신호(Chaotic signal)를 남긴다. 이 외부 꼬임 불안정성 모드가 발현됐을 때, 자기 재결합(Magnetic reconnection)을 통한 Flux rope들의 결합이 일어날 수 있다. 이 영역에서 자기 재결합에 의한 이온 온도 증가와 방전 전력은 선형 관계를 보여준다. 축 방향 자기장 성분은 플럭스 로프의 꼬임 불안정성을 억제할 뿐 아니라, 결합 활동을 억제하는 반발력(repulsing force)을 제공한다. 자기 플럭스 로프들 사이의 간격이 감소했을 때, 이온 온도의 증가가 관찰됐으며, 이는 3D 자기 재결합 구조를 감안한 재결합 각도(reconnection angle) 계산 결과와 동일한 경향을 보여준다. 이 연구를 통해 얻어진 중요한 조건 중 하나는 한정된 방전 전원으로 3D구조의 플럭스 로프 결합을 위해서는 자기장 세기의 상한 값이 있다는 것이 확인되었다. 이 범위 안에서 로프들의 결합이 일어날 수 있다. 결합(Merging) 과정을 위한 조건이 만족됐을 때, 또 다른 중요한 조건이 만족해야만 비로소 Toroidal 플라즈마 전류가 비유도적(Non-inductively)으로 구동될 수 있다. 이는 근접성(Proximity or coupling)으로, 3D 플럭스 로프들과 초기 플라즈마 사이의 간격을 의미한다. 오직 높은 근접성(high proximity)이 유지될 때, 증배 계수(Multiplication factor)가 ~10에 도달 가능했으며, 1.5 kA의 방전 전류로 15 kA의 플라즈마 전류가 구동 되었다. 전류 증가 시점에 증가된 CIII/CII 비율이 관찰되었으며, 이는 증가한 가둠 효율을 의미한다. FEM 법을 활용한 자기 재구성(Magnetic reconstruction) 결과는 토로이달 방향의 평균화된(Toroidally-averaged) 닫힌 플럭스 면을 보여준다. 높은 근접성이 유지될 때, 토로이달 전류의 증가와 함께, 봉우리 형태의 이온 온도 경향(Peaked profile of ion temperature)이 관찰되었으며, 이는 활발한 자기 재결합 현상이 일어나고 있음을 뜻한다. 흥미롭게도, 이때 플럭스 로프 속 꼬임 불안정성에 의한 자기 신호들이 사라지며, “Reduced n=1 MHD mode”와 유사한 특성을 보여준다. 방전이 마무리되는 시점에서는 지름 방향 힘의 균형(Radial force balance) 맞지 않아 근접성이 감소하고, 토로이달 전류의 감소가 나타나며 테일러 완화 과정이 중단된다. 플럭스 로프 속 외부 꼬임 불안정성에 의한 신호가 다시 나타나며, 평평한 형태의 이온 온도 경향(Flatted profile of ion temperature)이 나타난다. 3D 구조의 자기 플럭스 로프는 결합부터 국부 헬리시티 주입 과정까지 필수적인 역할을 한다. 진공 자기장 세기와 방전 전원 제어를 통한 3D 플럭스 로프의 안정성 모드 및 Merging 연구를 통해, 두가지 필수 운전 조건이 제안되었다. 방전 전력과 진공 자기장 제어성의 향상을 통해, 국부 헬리시티 주입을 통한 더욱 증가된 토로이달 전류가 기대된다.In tokamak configuration, increasing magnetic helicity, the linkage of toroidal and poloidal flux, means increasing toroidal plasma current, thereby increasing the performance of tokamak plasma. To inject magnetic helicity, DC (electrostatic) Local Helicity Injection (LHI) technique using 3D magnetic flux ropes has been developed. The LHI can be used as a means of current drive for tokamak and a non-inductive startup for the spherical torus (ST) that deals with the limited-central-inductive-flux swing. To use the LHI technique as a startup, the seed plasma in closed-flux-surface (CFS) should be formed by 3D magnetic flux ropes. With this seed plasma, the plasma current can be driven further via LHI and the Taylor relaxation process that convert the localized injected helicity into global helicity and macroscopic plasma current. Finally, a closed flux surface that resembles a tokamak plasma (tokamak-like state) can be formed. The operation using the LHI technique as a startup will fail without forming the seed plasma. One candidate of the MHD instabilities that can form a seed plasma in CFS is the merging between flux ropes undergoing current-driven kink instability in 3D helical geometry. However, the operational conditions required for forming seed plasma from the 3D magnetic flux ropes in ST remained unsolved, resulting in the possibility of operational failure. Therefore, understanding the profound physics of changing magnetic topology to a tokamak-like state from magnetic flux ropes in 3D helical geometry is the key to the successful operation of LHI as a startup method. So, the object of this thesis is to find the answer to the number of open questions regarding how to/ what physics related to reaching a Taylor relaxation process from the discharging 3D helical magnetic flux ropes. To form 3D helical flux ropes in VEST, the LHI system consisting of two arc plasma guns and two pulsed powers is developed and successfully commissioned. According to discharge conditions, the arc plasma guns can discharge flux ropes with a total current of 3 kA within a power of up to 1.5 MW. The typical normalized effective toroidal loop voltage value can range from 1.4 to 2.4 V-m. In this thesis, ion Doppler spectroscopy is used to measure ion temperature, which is used to evaluate merging activity. The main spectral line is CIII (464.7nm), the strongest impurity line in VEST. Before rope-rope merging takes place, the various MHD states in the 3D magnetic flux ropes discharged by arc plasma guns have been observed and analyzed. Magnetic diagnostics and spectroscopy confirm all these states without any invasive measurement. The axial magnetic field strength is the key to controlling the stability state of flux ropes. When the axial field strength is stronger than poloidal field strength driven by flux ropes, the flux ropes are in a stable state that the neutral pressure highly influences the temperature and density of the plasma. When the axial field strength is decreased, the coherent internal kink mode has appeared. The kink characteristics such as rotating frequency and deformation are calculated, which shows good agreement with experimental results. The coherent rotating model based on both phenomenological kink theory and the monoenergetic assumption is also developed, and its calculation results also agreed well with experimental measurement. By reducing the axial magnetic field further, the highly unstable external kink mode is appeared, leaving chaotic signals on the magnetic pick-up coil. With this external kink mode, the flux ropes can be merged via magnetic reconnection, resulting in a linear relationship between the discharge power and ion temperature. The axial magnetic field can act as both stabilizing force that the kink stability in flux ropes and repulsing force that suppresses the merging activity. When the distance between the ropes is reduced, the ion temperature is also increased, which is consistent with the calculation results that show an increased reconnection field angle in the 3D reconnection configuration. In this study, it is confirmed that there is a specific upper limit of the magnetic field strength to initiate merging between flux ropes for a given power range. The flux ropes can be merged by kink instability in flux rope within the limit. As the merging process is undergoing, one more condition should be met to drive toroidal plasma current non-inductively and continuously; proximity. Then the Taylor relaxation phase can be reached with sustained plasma by radial force balance. Only when the vertical magnetic field is adjusted to give high proximity between flux ropes and the seed plasma the multiplication factor has reached ~10 (more than the geometrical factor of 4), and the toroidal plasma current is driven up to 15 kA with an injection current of 1.5 kA. The increased CIII/II ratio is observed during the current ramp-up phase, meaning improved confinement. The magnetic reconstruction results using FEM show the formation of CFS in the toroidally averaged sense. As the coupling (proximity) between the toroidal plasma and flux ropes is maintained, the toroidal plasma current is driven non-inductively. At the same time, the edge localized peaked profile of ion temperature is measured at the low-field side, indicating where the strong reconnection activity takes place. Interestingly, the magnetic signals from kink mode in flux rope also disappeared, similar to “reduced-MHD mode” which is the newly discovered mode at the other device. At the end of discharge, as radial force is not balanced, the coupling is halted (decreased proximity), decaying the toroidal plasma, indicating the end of the Taylor relaxation phase. The external kink signal from the flux ropes appeared again. The magnetic flux rope in 3D helical geometry plays an essential role from the merging to the LHI phase. Based on studying the stability mode of 3D flux ropes, the experimental operational regime for a given injection power is suggested. The more increased toroidal plasma driven by the LHI is expected with increased injection power and vacuum field controllability.Abstract i Table of Contents v List of Tables vii List of Figures viii Chapter 1. Introduction and Motivation 1 1.1. Nuclear Fusion and Tokamaks 1 1.2. The need for non-inductive current-drive 3 1.3. Startup and Current drive via DC helicity injection 5 1.4. Merging activity during LHI 8 1.5. Goals of Thesis 12 Chapter 2. Theory and Prior Work 14 2.1. Arc plasma gun and its physics 14 2.2. Kink instability of flux ropes discharged by arc plasma gun 17 2.3. Magnetic reconnection and merging of flux ropes 22 2.4. Magnetic Helicity Conservation and Taylor Relaxation 29 Chapter 3. Experimental Setup 34 3.1. The VEST Machine 34 3.2. Diagnostics 37 3.2.1. Magnetic diagnostics 37 3.2.2. Spectroscopies 39 3.2.2.1. Ion Doppler Spectroscopy 39 3.2.2.2. Filterscope 41 3.2.2.3. Fast Camera 43 3.3. Helicity injection system 45 3.3.1. Arc plasma guns 45 3.3.2. Pulsed power systems 50 3.3.3. Plasma gun operation 60 Chapter 4. 3D helical flux rope merging 64 4.1. Kink instability in flux rope 65 4.1.1. MHD-Stable discharge 65 4.1.2. Identification of two kink modes [50] 72 4.1.3. Coupling to kink theory 79 4.2. Conditions for merging 88 4.2.1. Dependence of merging on the guide field 90 4.2.2. Dependence of merging on the field pitch 97 4.2.3. Impedance changes of flux rope during merging 102 4.3. Discussion 104 Chapter 5. Demonstration of local helicity injection 105 5.1. Conditions for transition to HI phase 105 5.1.1. The effect of proximity 105 5.1.2. Operating regime for LHI technique 120 5.2. Characteristics of plasma driven by LHI 126 5.2.1. Anomalous ion heating 126 5.2.2. Initial measurement of Te, ne profile 132 5.2.3. The MHD transition 135 Chapter 6. Conclusions and Future Work 140 6.1. Conclusions 140 6.2. Future work 140 Bibliography 142 국 문 초 록 146박

Identification of secondary chemistry teachers' ability to carry-out experimentation

The purpose of this study is to identify secondary chemistry teachers' abilities to carry-out experiment lesson successfully. As far as the research method is concerned, literature reviews, analyses of abilities to carry-out experimentation from science textbooks, and a survey of science teachers' perceptions of experimental ability were employed along with the progressive discussions among the authors. In order to identify secondary chemistry teachers' abilities to carry-out experimentation, we divided the experiment lesson into three stages of preparation, conduct and arrangement, and management of lab, and added the stage of safety. Each stage is classified into sub-areas, and the sub-area consists of subordinate elements. The safety stage was included separately to emphasize the importance of the safety issue in lab and experimental activities. The secondary chemistry teachers' abilities to carry-out experimentation are the abilities to perform experiments in person, presupposing the instruction of experiment, and can be featured with the use of reagent and measuring instruments, the preparation of sample, designing experiment, correct experimental habit and skillfulness, data processing, analysis and reasoning, and management of lab and safety

Solubility and decomposition kinetics of nitrous acid in aqueous solution

The Henry's law solubility and the decomposition reaction kinetics of nitrous acid (HNO2) in aqueous solutions have been determined by measuring the material distribution between the gas and liquid phase of the pertinent species with the use of a bubbler-type gas-liquid reactor in conjunction with a high-sensitivity chemiluminescence NOx detector. The pH-dependent solubility of N(III) (≡HNO2 + NO2-) was measured for the pH range 2.13-3.33. The Henry's law coefficient and the acid dissociation constant of HNO2 corresponding to 25°C are determined to be 49 ± 3 M atm-1 and (5.3 ± 0.4) × 10-4 M, respectively. The temperature dependence of the solubility over the range 0-30°C yielded AΔH°sol = -9.7 ± 0.3 kcal mol-1 and ΔS°sol = -24.8 ± 0.7 cal mol-1 K-1. The rate constants of the aqueous-phase reactions 2HNO2 ⇄ NO + NO2 + H2O (5) and 2NO2 + H2O → H+ + NO3- + HNO2 (6) determined at 22.0 ± 0.1°C are ks = 13.4 ± 1.0, k-5 = (1.6 ± 0.1) X× 108, and k6 = (8.4 ± 1.5) × 107, all in units of M-1 s-1. The values of ΔG°sol and ΔS°sol for the dissolution of HNO2 determined in this work are at variance with the latest values recommended by the National Bureau of Standards but are essentially identical with the previously selected set of values. The rather limited solubility of HNO2, in combination with its low atmospheric concentrations, suggests that HNO2 by itself contributes insignificantly to the acidification of atmospheric water, e.g., cloudwater. However, aqueous-phase reactions that produce HNO2 followed by degassing remain a plausible route for the production of atmospheric HNO2. © 1988 American Chemical Society

Misunderstanding and understanding of the phase diagram for water: Water evaporation and ice sublimation in the atmosphere

The purpose of this study is to suggest how to use the phase diagram for water to explain the evaporation and sublimation in lhe atmospheric condition. In principle, the phase diagram for water represents a one component system so it cannot be applied to the water contact with lhe air. When the liquid or solid phase of water exists in the air, always water vapor also exists in the air. In this case, we cannot present this state as a single point on the phase diagram because the pressure of the liquid or solid is different from that of the vapor in the air. However, since the saturation vapor pressure of liquid or solid is altered by negligible amount due to tbe presente of air, the evaporation and sublimation in the atmospheric condition can be explained using the vapor pressure line and sublimation line on the phase diagram