Asymptomatic hyperuricemia is independently associated with coronary artery calcification in the absence of overt coronary artery disease: A single-center cross-sectional study

Recently, the pathogenic role of uric acid (UA) in both systemic metabolic and atherosclerotic diseases has been investigated. We sought to determine the independent correlation between serum UA levels and coronary artery calcification, as a marker of subclinical atherosclerosis. A total of 4188 individuals without prior coronary artery disease or urate-deposition disease were included. All of the participants underwent multidetector computed tomography (MDCT) for the evaluation of coronary artery calcification (CAC) during their health check-ups. The subjects were divided into thre groups according to CAC scores (group 1: 0; group 2: 1-299; group 3: ≥300). After controlling for other confounders, serum UA levels were found to be positively associated with increasing CAC scores (P = 0.001). Adjusted mean serum UA levels in each CAC group were estimated to be 5.2 ± 0.1 mg/dL, 5.3 ± 0.1 mg/dL, and 5.6 ± 0.2 mg/dL from groups 1, 2, and 3, respectively. Subsequent subgroup analyses revealed that this positive association was only significant in participants who were male, relatively older, less overweight, and did not have diabetes mellitus (DM), hypertension, smoking history, or renal dysfunction. In conclusion, serum uric acid levels were independently associated with CAC score severity and this finding is particularly relevant to the subjects who were male, relatively older, less overweight (body mass index < 25 kg/m), and without a history of DM, hypertension, smoking, or renal dysfunction.ope

한국 해운산업의 수익성 하락 원인과 제고 방안에 관한 연구

최근 해운산업의 수익성이 하락하게 된 주요인은 이전 해운시장 대호황으로 인한 경쟁적 발주와 일부 해운사들의 생존전략 혹은 경쟁우위를 확보를 위한 대형선박으로 선대 교체 등으로 인한 선복량 과잉이다. 이는 물동량이 꾸준히 증가하고 있다는 점, 연료비가 2011년 이후 큰 변동이 없다는 점, 물동량/선복량 증가율 상대비교 등을 통해 확인할 수 있었다. 해외 주요 해운회사들은 상대적으로 우월한 유동성을 바탕으로 선대의 대형화와 교체를 할 수 있었고, 선대 경쟁력을 통한 영업력 강화와 단위당 고정비 절감을 통해 시황악화에서도 수익성을 제고할 수 있었다. 실증분석을 통해 매출액, 총자산, 운전자금(현금흐름)과 해운기업의 수익성은 비례하고, 부채비율과 차입금은 수익성에 반비례한다고 해석 할 수 있었다. 최근 한국 해운산업의 유동성 지원을 위한 제도로 선박투자회사제도, 선박매입프로그램, 선박은행 등이 있으나, 각 제도들은 일시적인 유동성 공급을 통해 숨통을 터주는 역할을 수행하였지만 부채 상승효과, 중고선가 하락 시 수익성 훼손 등의 문제가 있다. 본 연구는 선박운용사를 대안으로 제언하였다. 선박운용사는 한계 해운회사의 중고선 매입이 아닌, 신조발주를 하여 해당 선박을 해운회사에 대선하여 수익을 창출하는 사업모델이다. 선박운용사는 해운기업의 영업경쟁력 및 원가경쟁력을 확보할 수 있는 방안이 될 것이다.제1장 서 론 1 제1절 연구 배경 및 목적 1 제2절 연구의 범위 및 방법 3 제3절 연구의 구성 및 흐름 4 제2장 해운산업의 수익성과 해운환경 변화 6 제1절 해운산업의 수익성 변화 6 1. 부정기선 해운시장 8 2. 정기선 해운시장 11 제2절 국제 환경 규제 강화 15 1. EEDI(Energy Efficiency Design Index) 15 2. ECAs(Emission Control Area) 17 제3절 한국 해운산업의 흐름과 경영실태 19 1. 한국 해운산업의 발전흐름 19 2. 한국 해운산업의 경영실태 21 제4절 국내외 해운산업의 수익성 비교 23 제5절 각국 해운산업 지원 현황 29 1. 해외 주요 해운국가의 지원 현황 29 2. 한국의 지원 현황 30 제3장 이론적 배경과 선행연구 38 제1절 기업 수익성의 이론적 배경 38 제2절 선행연구 40 제4장 실증 분석 42 제1절 연구 설계 42 1. 연구의 대상 및 분석 방법 42 2. 변수의 선정과 측정 43 3. 가설 설정 44 제2절 수익성 영향요인 분석결과 47 1. 분석모형 및 관계분석 47 2. 최종 검증식과 검증 결과 50 3. 가설검증 결과 요약 53 제3절 수익성 제고를 위한 신규 지원 모델 제언 55 제5장 결론 58 제1절 연구의 요약과 시사점 58 1. 연구의 요약 58 2. 연구의 시사점 60 제2절 연구의 한계와 향후 연구과제 61 참 고 문 헌 6

Estimation and Testing for Separable Covariance

학위논문 (석사) -- 서울대학교 대학원 : 자연과학대학 통계학과, 2021. 2. 임요한.분할가능 행렬은 반복측정 다변량 자료, 시공간 자료 등에서 주로 나타날 수 있는 공분산 행렬의 구조 중 하나이다. 공분산 행렬의 분할가능성을 검정하는 방법은 그동안 꾸준히 발견되어 왔지만, 각자 다른 조건 하에서 연구가 진행되어 왔기에 이를 체계적으로 정리하고 앞으로 나아갈 점을 살펴볼 필요성이 대두되었다. 이를 위해 우선 정규분포 가정 하에서 가장 기초적인 방법들인 최대가능도 추정량과 가능도비 검정의 구체적인 표현을 살펴보고, 가능도비 검정의 단점을 보완할 수 있는 순열 검정에 대해서 자세히 알아보았다. 또한 정규분포 가정을 타파하기 위해 두꺼운 꼬리 분포에 대해 조사한 후, 이들 분포에 새로이 적용할 수 있는 추정량에 대해서 추가로 알아보았다. 마지막으로 두꺼운 꼬리 분포와 그에 알맞는 추정량을 사용한 검정에 대해 고찰해보고, 이러한 검정을 설계하는 데 있어서 주의할 사항에 대해서도 고찰해보았다.The separable matrix is one of the structures of covariance matrices that can mainly appear in repeated measure multivariate data and spatio temporal data. Methods to test the separability of the covariance matrix have been discovered steadily, but research has been conducted under different conditions, so the need to systematically organize them and examine future points has emerged. To this end, we first looked at the most basic methods under the assumption of normal distribution, the concrete expressions of the maximum likelihood estimator and the likelihood ratio test, and then examined in detail the permutation test that can compensate for the shortcomings of the likelihood ratio test. In addition, we investigated the heavy-tailed distributions to break the assumption of the normal distribution, and we additionally investigated the estimators that can be newly applied to these distributions. Finally, we discussed the test using heavy-tailed distributions and estimators suitable for it, and also considered the points to be aware of in designing such a test.제 1 장. 서 론 2 제 2 장. 분할가능 공분산 행렬 4 제 3 장. 분할가능 공분산 행렬의 추정 5 제 4 장. 공분산의 분할가능성에 대한 검정 7 제 1 절. 가능도비 검정 7 제 2 절. 순열 검정 8 제 5 장. 두꺼운 꼬리 분포로의 확장 11 제 1 절. 타원 분포 (EL) 11 제 2 절. 일반화된 타원 분포 (GEL) 12 제 3 절. 변환된 타원 분포 (TEL) 13 제 6 장. 논 의 14 참고문헌 15 Abstract 16Maste

Development of Science Museum Exhibition Contents for Youth Education Developed by Science and Engineering College Students

The purpose of this study is for science and engineering students to experience social contribution through voluntary projects. The method of research is to create and introduce the exhibits and its exhibition commentary of Science Museum for local youth. The exhibition commentary is a project that stimulates student‘s interests in science and technology by providing scientific knowledge and research information. Producing exhibits is a project that discovers local technologies as well as introduces its history, technology, and scientific principles to young students. Two projects confirmed the positive effects of creating opportunities for science and engineering students to contribute to society and expanding scientific content, and showed implications for engineering education.2

A Study on Engineering Education Model for Citizen - Focusing on the Connection Program Between Colleges of Science and Engineering and Science Museums -

The purpose of this study is to propose a strategy model for engineering education for citizen through the connection between colleges of science and engineering and science museums as a way to achieve citizen science. For this model, the role of universities was redefined as social contributions through engineering education from the perspective of knowledge triangle and university entrepreneurship. In addition, the science museum was re-examined as an engineering education platform and selected as an institution that supports the contribution of colleges to society. For practical model development, the connection types of these two institutions were analyzed as case studies and interview to collect opinions from experts in the science museum. In this process, convergence education content development, reinforcement of college-science museum linkage, infrastructure construction, development of college resource utilization plans, and maintenance and expansion of educational programs diversification were derived as components for model development. Based on this, engineering education model for citizen was presented that matches educational programs according to the type of participation of colleges including key factors and considerations.2

Hyperuricemia and risk of increased arterial stiffness in healthy women based on health screening in Korean population.

Hyperuricemia is a risk factor for cardiovascular disease and is associated with increased arterial stiffness in high-risk populations. However, given the possible sex-related differences in the prevalence of hyperuricemia, the association between elevated serum uric acid (SUA) level and increased arterial stiffness has yielded conflicting results. We investigated the relationship between SUA and arterial stiffness in asymptomatic healthy subjects who underwent a health examination. Subjects who underwent a comprehensive health examination were enrolled. After exclusion of extensive confounding factors, 2,704 healthy subjects with coronary calcium score < 100 were evaluated in the final analysis. All subjects underwent brachial-ankle pulse wave velocity (baPWV) to detect arterial stiffness. The SUA was divided into quartiles for its association with arterial stiffness and was analyzed separately for men and women. The mean SUA level was significantly lower in women than in men. The baPWV was significantly elevated in subjects with the highest quartile of SUA in women, but not in men. After adjusting for age, smoking, systolic blood pressure, body mass index, estimated glomerular filtration rate, fasting plasma glucose, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, and coronary artery calcium score, the highest quartile of SUA in women was significantly associated with increased risk of high baPWV compared with the lowest quartile of SUA (OR = 1.7, p = 0.018), whereas in men, SUA level was not associated with high baPWV. Our study showed that elevated SUA is independently associated with increased baPWV in healthy Korean women, but not in men.ope