Study on the Novel PRAM cell structure for reducing reset current

본 논문에서는 차세대 메모리인 상변화 메모리(Phase change random access memory)의 지우기 전류 감소를 위한 새로운 셀 구조에 관해 고찰하였다. 기록, 소거, 재생 속도, 재기록, 횟수 등을 포함한 성능에서 DRAM 급의 성능 특성을 가지며 소자구조 및 제작공정이 단순하여 정보저장 및 처리 용량대비 저가격화 달성이 용이한 상변화 메모리(PRAM)가 차세대 비휘발성 메모리로 주목 받고 있다. 그러나 상변화 메모리의 지우기 동작전류는 타 메모리 소자에 비해 큰 값을 나타내는 단점이 있어 상변화 메모리가 기존의 메모리 소자를 대체하기위한 경쟁력을 갖추기 위해서는 지우기 동작 전류를 낮추어야 한다. 상변화 메모리의 지우기 동작 전류를 낮추기 위해 상변화 물질, 발열전극 물질 및 셀 구조 변화 등의 연구가 진행 중이다. 그 중에서 셀 구조를 변형함으로써 지우기 전류를 줄여보고자 하는 연구가 이루어지고 있다. 본 연구는 PRAM의 지우기 전류를 줄이기 위해 상변화 물질 자체를 발열체로 사용하는 Pore형 PRAM 소자를 제작하여 소자 특성을 조사하였다. 또한 3차원 유한 요소 해석 프로그램을 이용하여 나노 스케일 PRAM의 GST박막의 두께에 따른 PRAM의 지우기 전류와 온도에 관해 조사하였고, 상변화 물질의 두께가 얇아질수록 지우기 전류가 증가하는 것을 알게 되었다. 지우기 전류의 증가를 막기 위해 SiO₂ 열 방지층을 사용하는 새로운 구조의 PRAM cell을 제안하였고 또한 지우기 전류와 온도에 관한 조사를 하였다. 200 ㎚ 의 두께의 GST박막의 두께에서 기존의 구조와 새로운 구조의 PRAM을 비교하였을 때, 새로운 구조의 PRAM cell에서 온도는 536.60 ℃ 에서 817 ℃ 로 크게 증가하였고, 지우기 전류는 17.4 ㎃ to 13.7 ㎃ 로 감소하였음을 알 수 있었다. 이 결과는 새로운 구조의 PRAM cell이 열 방지층으로서 효과적으로 작용해 지우기 전류를 감소시킴을 알 수 있었다.Today, the market for non-volatile memory is dominated by the Flash technology. Due to the increasing cost of down scaling Flash technology, the memory industry is searching for alternative memory concept. One of most promising candidates is the electrical phase change technology PRAM. In this paper, we fabricated the PRAM unit cell and investigated electro and thermal characteristics of PRAM unit cell with novel structure using SiO₂ heat blocking layer. As thickness of GST thin film decreased from 400 ㎚ to 300 ㎚, reset current and temperature changed a bit but did not affect so much memory cell operation. But as thickness of GST thin decreased from 300 ㎚ to 200 ㎚, reset current increased from 15 ㎃ to 17.4 ㎃ and temperature decreased from 704.86 ℃ to 536.60 ℃. As reset current and temperature changed like at 200 ㎚ thickness of GST thin film, the memory cell operation did not work as normal. From this results, we investigated material parameters of heater electrode for why reset current and temperature changed. After investigation, we found that heat which was generated between phase change material GST and heater electrode TiN was given to top electrode W due to thin thickness of GST thin film. We have throughly investigated the decreasing of temperature of 200 ㎚ thickness of GST thin film and found that the severe heat loss occurred at top electrode. In the case of 200 ㎚ thickness of GST thin film, a heat rapidly transferred to top electrode before melting temperature. A heat which contacted with top electrode transferred easily to outside and temperature decreased. Therefore, novel structure PRAM which deposited SiO₂ blocking layer instead of part of top electrode was proposed. The SiO₂ blocking layer which is dielectric layer can protect the heat to give off through top electrode. In comparison with conventional PRAM at 200 ㎚ GST thin film thickness, temperature of novel structure PRAM highly increased from 536.60 ℃ to 817 ℃ and reset current of novel structure PRAM decreased abruptly. from 17.4 ㎃ to 13.7 ㎃. This result shows that novel SiO₂ blocking layer of PRAM successfully protected heat to give off to top electrode.Chapter 1. Introduction = 1 Chapter 2. What is the PRAM = 4 2.1 Definition and background of the PRAM = 4 2.2 Theory of operation = 7 2.3 Method of reduction of reset current = 11 2.4 Electromagnetic analysis = 12 2.5 Thermal analysis = 14 Chapter 3. Experimental = 17 3.1 Fabrication procedure = 17 3.2 Finite element analysis = 21 Chapter 4. Results and discussion = 24 4.1 Electro-thermal characteristics of the PRAM = 24 4.1.1 Electrical property = 24 4.1.2 Electro-thermal analysis = 27 4.1.3 Effect of thickness of Ge2Sb2Te5 = 29 4.2 Effect of novel structure PRAM unit cell with heat blocking layer = 33 4.2.1 Finite element analysis model = 33 4.2.2 Electro-thermal analysis = 34 4.3 Effect of heat blocking layer in planar type PRAM = 38 4.3.1 Electro-thermal analysis = 38 4.3.2 Effect of heat blocking layer = 41 Chapter 5. Conclusion = 45 Chapter 6. Reference = 4

Inflammatory Responses in the Muscle Coat of Stomach and Small Bowel in the Postoperative Ileus Model of Guinea Pig

PURPOSE: Small intestinal function returns first after surgery, and then the function of the stomach returns to normal after postoperative ileus (POI). The aim of this study was to investigate inflammatory responses in the muscle coat of stomach and small intestine in guinea pig POI model. MATERIALS AND METHODS: The distance of charcoal migration from pylorus to the distal intestine was measured. Hematoxylin and eosin (H&E) and immunohistochemical stain for calprotectin were done from the histologic sections of stomach, jejunum and ileum obtained at 3 and 6 hour after operation. Data were compared between sham operation and POI groups. RESULTS: The distance of charcoal migration was significantly reduced in the 3 and 6 hour POI groups compared with sham operated groups (p<0.05). On H&E staining, the degree of inflammation was significantly higher in the stomach of 3 hour POI groups compared with jejunum and ileum of POI groups or sham operated groups (p<0.05). Calprotectin positive cells were significantly increased in the muscle coat of stomach of 3 hour POI groups compared with jejunum and ileum of POI groups or sham operated groups (p<0.05). There was strong association between the degree of inflammation and calprotectin positive cells in stomach. CONCLUSION: Postoperative ileus induced by cecal manipulation significantly increased the degree of inflammation and calprotectin positive cells in the muscle coat of stomach as a remote organ. The relevance of degree of inflammation and the recovery time of ileus should be pursued in the future research.ope

A Case of Pancreatic Metastasis From a Papillary Thyroid Carcinoma Mimicking Pancreatic Cancer

Papillary thyroid cancer (PTC) has a good prognosis and a low incidence of distant metastases. It is extremely rare for PTC to metastasize to the pancreas. Only five cases have been previously reported worldwide. Most cases are discovered incidentally by abdominal computed tomography (CT) or positron emission tomography-CT (PET-CT) during follow-up studies after thyroidectomies. Pancreatic metastasis of PTC is usually unidentifiable by a whole-body I131 scan, a common follow-up modality. When a pancreatic mass is found in patients with PTC, it must be differentiated from pancreatic cancer. In previous reports, patients with pancreatic metastases of PTC underwent operations for therapeutic diagnosis or underwent fine needle aspiration biopsies (FNAB). However, it is unclear whether the benefit of an operation outweighs the risk. We experienced a case of PTC with pancreatic metastasis that was found on PET-CT. Contrast-enhanced endoscopic ultrasonography (EUS) was performed to evaluate the characteristics of the pancreatic mass and pathological confirmation was obtained cytologically via EUS-FNA.ope

기니 픽의 수술 후 장폐색 모델에서 위장, 소장의 근육층 내 염증 변화

Dept. of Medicine/석사Purpose: Small intestinal function returns first after surgery, and then thefunction of the stomach returns to normal after postoperative ileus (POI). Theaim of this study was to investigate inflammatory responses in the muscle coatof stomach and small intestine in guinea pig POI model.Materials and Methods: The distance of charcoal migration from pylorus tothe distal intestine was measured. Hematoxylin and eosin (H&E) andimmunohistochemical stain for calprotectin were done from the histologicsections of stomach, jejunum and ileum obtained at 3 and 6 hour afteroperation. Data were compared between sham operation and POI groups.Results: The distance of charcoal migration was significantly reduced in the 3and 6 hour POI groups compared with sham operated groups (p<0.05). OnH&E staining, the degree of inflammation was significantly higher in thestomach of 3 hour POI groups compared with jejunum and ileum of POIgroups or sham operated groups (p<0.05). Calprotectin positive cells weresignificantly increased in the muscle coat of stomach of 3 hour POI groupscompared with jejunum and ileum of POI groups or sham operated groups(p<0.05). There was strong association between the degree of inflammation2and calprotectin positive cells in stomach.Conclusion: Postoperative ileus induced by cecal manipulation significantlyincreased the degree of inflammation and calprotectin positive cells in themuscle coat of stomach as a remote organ. The relevance of degree ofinflammation and the recovery time of ileus should be pursued in the futureresearch.ope

Accuracy of clear aligner attachment build-up using PET-G positioners and composite resin

본 연구의 목적은 3차원 출력된 치아모델을 이용하여 투명교정장치용 어태치먼트를 정확히 형성하는데 영향을 줄 수 있는 요소들을 평가하고자 한다. 상악 석고 모델을 3차원 스캔하고 원본스캔 파일로 저장하였다. 상악 우측 및 좌측 중절치 순면 중앙에 타원형 어태치먼트를 디자인하고 어태치먼트의 절단측과 치경부측에 2개의 레퍼런스 콘을 추가한 뒤 스캔 모형의 기저부는 교합평면에 45도가 되도록 잘라내고 어태치먼트디자인 파일을 완성하였다. 원본스캔 파일과 어태치먼트디자인 파일을 폴리젯 프린터를 이용하여 출력하였고 각각 원본스캔 파일과 어태치먼트디자인 출력물로 명명하였다. 어태치먼트 형성을 위한 포지셔너는 어태치먼트 디자인 출력물에 압력 성형기 또는 흡입 성형기로 열성형 시트지를 밀착하여 제작하였다. 포지셔너에 압축형 또는 유동형 복합레진을 채워 원본 출력물에 어태치먼트를 형성하였다. 어태치먼트가 형성된 모델은 어태치먼트형성 출력물로 명명하였다. 어태치먼트디자인 출력물과 어태치먼트형성 출력물은 3차원 스캔 후 어태치먼트디자인출력물 스캔파일과 어태치먼트형성출력물 스캔파일로 저장하였다. Geomagic Control X를 사용하여 어태치먼트디자인 파일, 어태치먼트디자인 출력물 스캔파일과 어태치먼트형성출력물 스캔파일을 3차원 중첩 후 비교하였다. 형성된 어태치먼트의 정확도를 비교하기 위해 2개의 평면(시상, 횡단)과 5개의 계측점(절단, 치경부, 근심, 원심, 중앙)을 설정하였다. 각각의 계측점에서 어태치먼트디자인 파일, 어태치먼트디자인출력물 스캔파일과 어태치먼트형성출력물 스캔파일 간 거리값을 측정하였고 전체 실험군을 복합레진 종류와 포지셔너 제작 방식에 따라 나누어 통계분석을 시행하였다. 본 연구에서 다음과 같은 결론을 얻었다. 1. 압력 성형기와 흡입 성형기를 이용하여 제작한 포지셔너를 이용한 어태치먼트 형성 오차 비교 시 통계적 유의차가 없었다. 2. 압축형 복합레진을 사용할 경우 유동형 복합레진에 비하여, 초기 계획 위치보다, 어태치먼트는 더 절단 방향으로 변위 되었다. 3. 어태치먼트 디자인 모델 출력 시 발생하는 오차와 어태치먼트 형성 시 발생하는 오차를 더한 총오차의 크기는 수직 수평적으로 평균 약 0.2mm로 추정된다 |This study aimed to evaluate the errors occurring in the formation of an attachment manufactured using a composite resin and positioner by scanning the experimental models at each stage of the formation process. A study model of the maxilla was scanned and saved. The ellipsoidal attachment for the central part of the labial surface of both the maxillary central incisors was designed, and the two reference cones were added to the sides of the cervical and incisal parts. The basal part of the original study model scan file was cut at a 45-degree angle to the occlusal plane and was named the attachment design file. The original study model scan file and attachment design file were printed out using a PolyJet printer, and the resulting printed models were named the original printed model and attachment design printed model, respectively. The attachment design printed model was used to manufacture the attachment positioner by using two methods employing pressure-type and vacuum-type machines. The buildup model of the complete attachment was called the attachment buildup printed model, and the attachment design printed model and attachment buildup printed model were stored after scanning them with a 3D scanner. The attachment design file, attachment design printed model scan file, and attachment buildup printed model scan file were superimposed and compared to each other by using Geomagic Control X. For 3D comparison, two reference planes (sagittal and transverse) and five measurement points (incisal, cervical, mesial, distal, and central) were set. The distance from each measurement point to the attachment design file, attachment design printed model scan file, and attachment build-up printed model scan file were measured, and the entire experimental group was classified into subgroups corresponding to the types of composite resin and methods of positioner manufacturing to conduct statistical analyses. Several conclusions can be drawn from this study. 1. No statistically significant difference was observed in the comparison of the build-up error when using the positioner manufactured by employing pressure-type and vacuum-type machines. 2. The attachment showed greater incisal displacement from the initially planned position when using a packable composite resin than when using a flowable composite resin. 3. The sum of the errors in the attachment design printed model and the errors in the attachment build-up printed model was estimated to be approximately 0.2 mm in the sagittal and transverse directions.Docto

A Study on the Double-Entry Accounting System in Korean Local Governments

학위논문(석사)--아주대학교 경영대학원 :경영일반MBA,2010. 8발생주의에 의한 복식부기회계제도를 지방자치단체에서 도입하면서 경기도에서 적용하고 있는 사례와 외국의 도입실태 그리고 문헌을 중심으로 복식부기회계제도의 문제점과 발전방안에 대하여 연구&#8228;분석하였다. 2007년부터 복식부기회계가 우리나라 지방자치단체에 전면 실시되고 있다고는 하나 현재 기존의 단식부기와 복식부기가 각각 병행하여 시행되고 있는 등 미완의 단계에 있고 지금도 제도의 안정적 정착을 위해 보완하여야 할 과제들이 많다는 것을 알 수 있었으며, 외국의 사례와 문헌을 종합 분석한 결과, 현재 우리의 발생주의 복식부기회계는 종합재정상태 및 재정운영성과의 파악이 가능하도록 기초가 마련된 단계까지 발전하였으나 아직도 많은 문제점이 있으며 앞으로 많은 개선이 필요하다.第1章 序論 1 第1節 연구의 목적 1 第2節 연구방법 2 1. 논문의 구성 3 第2章 복식부기회계제도의 도입배경 및 이론적 고찰 4 第1節 지방자치단체 복식부기회계제도의 도입 4 1. 지방자치단체 회계제도의 의의 4 2. 지방자치단체의 복식부기회계제도 도입 6 가. 복식부기회계제도의 도입 과정 6 나. 복식부기회계제도의 도입 효과 8 第2節 복식부기회계제도의 이론적 고찰 11 1. 복식부기회계제도와 발생주의회계 11 가. 복식부기회계제도 개요 11 나. 복식부기회계의 인식 기준 12 2. 지방자치단체 복식부기회계의 적용 원칙 15 3. 기존 예산회계 결산과 재무보고서와의 관계 16 第3節 선행연구 검토 17 1. 선행연구의 검토 17 2. 선행연구 요약 및 기존연구와의 차이점 20 第3章 복식부기회계제도의 운영사례 분석 22 第1節 선진 외국 운영 현황 22 1. 뉴질랜드 23 2. 미국 24 3. 영국 24 4. 호주 25 5. 일본 26 6. 독일 27 7. 외국사례의 시사점 28 第2節 경기도의 운영사례 29 1. 경기도 복식부기 회계제도 도입 및 운영 현황 29 2. 경기도 복식부기 담당부서 조직 및 업무 30 3. 경기도의 2008 회계연도 발생주의 복식회계에 의한 재무지표 분석 31 가. 재정상태 지표 32 나. 재정운영의 효율성 지표 34 다. 회계의 책임성 지표 36 4. 회계업무와 전산시스템과의 관계 42 가. 전산시스템의 개요 42 나. 회계업무의 전산처리 42 第4章 지방자치단체 복식부기회계제도 시행에 따른 문제점 43 第1節 회계기준 등 제도적 측면43 1. 자산에 대한 객관적 가치평가 매뉴얼 미흡43 2. 재정사업의 원가산정기준 미비 44 3. 재정보고서 작성 및 재정공시의 적시성 부족 44 第2節 복식부기회계 전산시스템 측면 46 1. 업무별 전산프로그램 연계기능 부족 46 2. 사업별 예산제도의 성과시스템 연계부족 46 第3節 복식부기회계 관리기능 측면 47 1. 업무의 전문성 부족 47 2. 재무정보의 부실화 우려 48 第5章 지방자치단체 복식부기회계제도의 발전방향 49 第1節 자치단체 복식부기회계제도의 지속적 보완 49 1. 지속적인 제도의 정비 및 보완 49 2. 성과(원가)정보 제공내용의 개선 49 第2節 전산시스템의 보완 49 1. 회계기준과 복식부기회계시스템의 상호연계 51 2. 기존 회계시스템과 상호 연계한 전산시스템의 개발 51 第3節 성과주의 예산과의 연계 및 재무보고 체계 개선 52 1. 성과주의 예산과의 연계 52 가. 성과평가의 필요성 53 나. 성과측정치 53 다. 지방자치단체의 수익사업에 대한 평가 53 2. 지방자치단체 재무보고체계 개선 및 결산순기 단축 54 第4節 복식부기회계제도 정착을 위한 인식의 변화 56 1. 단체장의 관심도 제고 56 2. 회계정보 생산자와 이용자의 인식변화 56 第5節 복식부기회계제도의 안정적 정착을 위한 신규제도 도입 57 1. 정부회계사제도 도입 검토 57 2. 재무결산 심의기구 신설 검토 58 第6章 결론 59 第1節 연구의 결과 및 시사점 59 1. 연구의 결과 59 2. 연구의 시사점 60 第2節 연구의 한계점 및 향후 연구 과제 61MasterThis paper studies problems of the accrual-based double-entry bookkeeping system and how to improve this system through literature and cases of the Gyeonggi Provincial Government and foreign local governments. The system, which Korean local governments have adopted since 2007, and often used jointly with conventional single-entry bookkeeping, still needs to be improved in many ways. First, the computerized local financial system should be developed so as to connect the current project-based budgetary system with the performance-based budgetary system currently in development. Second, it is crucial that people, including the leaders and public officials of local governments as well as local councilmen and citizens, should change their attitude towards the double-entry bookkeeping system. Instead of avoiding the system because of its unintelligibility and intricacy, they should be willing to learn and adopt the system. Third, local governments should seriously consider introducing a government-certified public account system and/or treasury account deliberative body in order to secure expertise in government accounting and provide faultless information. In addition, it is necessary to advance the closing accounts for the sake of financial-information users' convenience. In conclusion, this study finds from the analysis of foreign cases and literature that the accrual based double-entry bookkeeping system in Korea still has many problems to resolve and needs to be improved in spite of its accomplishments including an integrated financial system and financial performance evaluation system

Trying to win the war against antibiotics resistance

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상아모세포의 조건배지를 이용한 백악모세포의 분화와 석회화 조절

For the regeneration of periodontal tissues, the microenvironment for new attachment of connective tissue fibers should be provided, At this point of view, cementum formation in root surface plays a key role for this new attachment. This study was performed to figure out which factor promotes differentiation of cementoblast Considering anatomical structure of tooth, we selected the cells which may affect the differentiation of cementoblast - Ameloblast, OD11&MDPC23 for odontoblasts, NIH3T3 for fibroblsts and MG63 for osteoblasts. And OCCM30 was selected for cementoblast cell line. Then, the cell lines were cultured respectively and transferred the conditioned media to OCCM30. To evaluate the result, Alizarin red S stain was proceeded for evaluation of mineralization. The subjected mRNA genes are bone sialoprotein(BSP), alkaline phosphate(ALP) , osteocalcin(OC), type I collagen(Col I), osteonectin(SPARC ; secreted protein acidic and rich in cysteine). Expression of the gene were analysed by RT-PCR, The results were as follows: 1. For alizarin red S staining, control OCCM30 didn't show any mineralized red nodules until 14 days. But red nodules started to appear from about 4 days in MDPC-OCCM30 & OD11-OCCM30. 2. For results of RT-PCR, ESP mRNAs of control-OCCM30 and others were expressed from 14 days, but in MDPC23-OCCM30 & OD11-OCCM30 from 4 days. Like this, the gene expression of MDPC23-OCCM30 & OD11-OCCM30 were detected much earlier than others. 3. For confirmation of odontoblast effect on cementoblast, conditioned media of osteoblasts(MG63) which is mineralized by producing matrix vesicles didn't affect on the mineralized nodule formation of cementoblasts(OCCM30). This suggest the possibility that cementoblast mineralization is regulated by specific factor in dentin matrix protein rather than matrix vesicles. Therefore, we proved that the dentin/odontoblast promotes differentiation/mineralization of cementoblasts. This new approach might hole promise as diverse possibilities for the regeneration of tissues after periodontal disease.본 연구는 교육인적자원부 누리사업 국고보조금으로 수행한 과제입니다