• 한국대기환경학회지
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• 제32권5호
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• pp.457-468
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• 2016

Traffic-related air pollutants and particulates from diesel exhaust cause for increasing respiratory health problem. Recent epidemiologic studies have reported adverse effects of urban air pollution on various aspects of respiratory health. Bus or truck terminal workers have high probability of exposure to diesel exhaust particle than general office worker. This study was designed to evaluate the relationship between pulmonary function of people who working at the high-density area of diesel vehicles and pulmonary function of people who working at general office in Seoul. So, this study explored the effects on people with exposure to diesel traffic or exposure to diesel traffic, through the pulmonary function test (PFT). There were significant difference in Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 second ($FEV_1$) between high-exposure group and control. High-exposure to diesel particle were increased risk of reduction in pulmonary function in this study. These results provide the necessity additional research that manage people who working at the high-density area of diesel vehicles.

• 한국항공우주학회지
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• 제43권5호
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• pp.413-421
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• 2015

큐브위성은 2003년 처음 발사된 이후로 지금까지 230기 이상이 발사되었다. 작은 크기와 가벼운 무게로 인해 발사비용이 저렴한 큐브위성은 일반적인 발사체의 남는 공간을 이용하여 발사되고 있다. 그러나 이러한 발사 방법은 주 탑재위성의 준비일정에 따라 발사 일정이 유동적인 단점이 있다. 이에 새로운 대안으로 정기적이고 발사횟수가 많은 국제우주정거장 물자수송 발사체를 이용하여 큐브위성을 ISS로 운송한 뒤에 로봇팔을 이용하여 발사하는 방법이 제안되고 있다. 본 논문에서는 국제우주정거장에서 분리되는 방향과 각도에 따라 생성되는 큐브위성의 궤도를 분석하였다. 또한 분석되는 궤도에 따른 임무수명과 ISS와의 충돌 가능성을 분석하여 충돌 위험을 최소화하고 위성수명을 최대로 하는 최적의 로봇팔 각도를 계산하였다.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.527-537
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• 2004

Consequence-Based Engineering (CBE) is a new paradigm proposed by the Mid-America Earthquake Center (MAE) to guide evaluation and rehabilitation of building structures and networks in areas of low probability - high consequence earthquakes such as the central region of the U.S. The principal objective of CBE is to minimize consequences by prescribing appropriate intervention procedures for a broad range of structures and systems, in consultation with key decision makers. One possible intervention option for rehabilitating unreinforced masonry (URM) buildings, widely used for essential facilities in Mid-America, is passive energy dissipation (PED). After the CBE process is described, its application in the rehabilitation of vulnerable URM building construction in Mid-America is illustrated through the use of PED devices attached to flexible timber floor diaphragms. It is shown that PED's can be applied to URM buildings in situations where floor diaphragm flexibility can be controlled to reduce both out-of-plane and in-plane wall responses and damage. Reductions as high as 48% in roof displacement and acceleration can be achieved as demonstrated in studies reported below.

• Asian Pacific Journal of Cancer Prevention
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• 제17권2호
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• pp.867-872
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• 2016

Background: Esophageal cancer is one of the most serious malignancies. Due to the aggressive nature of this cancer, the prognosis is poor. A network meta-analysis with simultaneous comparison of multiple treatments can help determine better treatment options that have higher effects on overall survival of patients with lower adverse events. The aim of this review is to simultaneously compare efficacy and adverse events of treatment interventions for esophageal cancer. Materials and Methods: In this review, only randomized control trials (RCT) will be considered for network meta-analysis. All international electronic databases including Medline, Web of Sciences, Scopus, Cochran's library, EMBASE and Cancerlit will be searched to find randomized control trials which compared two or more treatment interventions for esophageal cancer. A network plot will be drawn for visual representation of all available treatment interventions. Bayesian approach will be used to combine the direct and indirect evidence. Treatment effects (e.g. hazard ratio for time to event outcomes, risk ratio for binary outcomes, and rate ratio for count outcomes with 95% credible interval) will be reported. Moreover, cumulative probability of the treatment ranks will be reported using the surface under the cumulative ranking (SUCRA) graphs. Consistency assumption will be assessed by the loop-specific and design-by-treatment interaction approaches. Conclusions: The results of this study may be helpful for the patients, clinicians and health policy makers in selecting treatments that have the best effect on survival and lowest adverse events.

• 대한의용생체공학회:의공학회지
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• 제38권3호
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• pp.123-128
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• 2017

Background and aims: The KCNQ1 S140G mutation involved in $I_{ks}$ channel is a typical gene mutation affecting atrial fibrillation. However, despite the possibility that the S140G gene mutation may affect not only atrial but also ventricular action potential shape and ventricular responses, there is a lack of research on the relationship between this mutation and ventricular fibrillation. Therefore, in this study, we analyzed the correlation and the influence of the KCNQ1 S140G mutant gene on ventricular fibrillation through computer simulation studies. Method: This study simulated a 3-dimensional ventricular model of the wild type(WT) and the S140G mutant conditions. It was performed by dividing into normal sinus rhythm simulation and reentrant wave propagation simulation. For the sinus rhythm, a ventricular model with Purkinje fiber was used. For the reentrant propagation simulation, a ventricular model was used to confirm the occurrence of spiral wave using S1-S2 protocol. Results: The result showed that 41% shortening of action potential duration(APD) was observed due to augmented $I_{ks}$ current in S140G mutation group. The shortened APD contributed to reduce wavelength 39% in sinus rhythm simulation. The shortened wavelength in cardiac tissue allowed re-entrant circuits to form and increased the probability of sustaining ventricular fibrillation, while ventricular electrical propagation with normal wavelength(20.8 cm in wild type) are unlikely to initiate re-entry. Conclusion: In conclusion, KCNQ1 S140G mutation can reduce the threshold of the re-entrant wave substrate in ventricular cells, increasing the spatial vulnerability of tissue and the sensitivity of the fibrillation. That is, S140G mutation can induce ventricular fibrillation easily. It means that S140G mutant can increase the risk of arrhythmias such as cardiac arrest due to heart failure.

• 한국의료질향상학회지
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• 제7권2호
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• pp.218-228
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• 2000

Background : Among 'structure', 'process' and 'outcome' approaches, outcome evaluation is considered as the most direct and best approach to assess the quality of health care providers. Risk-adjustment is an essential method to compare outcome across providers. This study has aims to judge performance of hospitals by severity adjusted mortality rates of coronary artery bypass graft (CABG) surgery. Methods : Medical records of 584 patients who got the CABG surgery in 6 general hospitals during 1996 and 1997 were reviewed by trained nurses. The MedisGroups was used to quantify severity of patients. The predictive probability of death was calculated for each patient in the sample from a multivariate logistic regression model including the severity score, age and sex. For evaluation of hospital performance, we calculated ratio of observed number to expected number of deaths and z score [(observed number of deaths - expected number of deaths)/square root of the variance in the number of deaths], and compared observed mortality rate with confidence interval of adjusted mortality rate for each hospital. Results : The overall in-hospital mortality was 7.0%, ranged from 2.7% to 15.7% by hospital. After severity adjustment the mortality by hospital was from 2.7% to 10.7%. One hospital with poor performance was distinctly divided from others with good performance. Conclusion : In conclusion, severity-adjusted mortality rate of CABG surgery might be applied as an indicator for hospital performance evaluation in Korea. But more pilot studies and improvement of methodologies has to be done to use it as quality indicator.

• 한국안전학회지
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• 제31권2호
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• pp.1-9
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• 2016

The standard procedure of fire modeling was reviewed to minimize the user dependence, based on the NUREG-1934 and 1824 reports. The hazard analysis of lubricating oil fires in the air compressor room of domestic nuclear power plant (NPP) was also performed using a representative fire model, FDS (Fire Dynamics Simulator). The area ($A_f$) and location of fire source were considered as major parameters for the realistic fire scenarios. As a result, the maximum probability to exceed the thermal damage criteria of IEEE-383 unqualified electrical cables was predicted as approximately 70% with $A_f=1m^2$. It was also found that for qualified electrical cables, the maximum probabilities of exceeding the criteria were 2% and 90% with $A_f=2$ and $4m^2$, respectively. It was concluded that all electrical cables should be replaced with IEEE-383 qualified cables and the dike to restrict as $A_f{\leq}2m^2$ should be installed at the same time, in order to assure the thermal stability of electrical cables for lubricating oil fires in the air compressor room of domestic NPP.

• 한국조경학회지
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• 제18권4호
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• pp.127-140
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• 1991

The Primary purpose of this study is to investigate factors and variables which have significant effects on user satisfaction with recreational facilities in Taejong-Dae recreational complex, thereby establishing indices of planning and development of urban parks and open space. To test the causal models of this research, the date were gathered by self-administered questionnaires from 967 households in Pusan City which were selected by the multi-stage probability sampling methood. The analysis of the multi-stage primarily consists of two phase : The first analysis dealt exploratory factor analysis which identified major factors involved in satisfaction with recreational activities and facilities in Taejong-Dae recreational complex and the second analysis tested the fit of the causal models of this research by employing LISREL methodology. There are three advantages of using LISREL over other multivariate analysis methods : First, measurement error is allowed and calculated in LISREL, otherwise there is a risk of seriously misleading estimates of coefficients ; Second, LISREL deals with latent variables or unmeasured variables ; Third, it enables to test causal relations among variables. The factors analysis identified that five factors are involved in satisfaction with recreational facilities. The five factors of satisfaction with recreational facilities are space for repose and relaxation, active recreation facilities such as pool and zoo, physical exercise facility, convenience and maintenance facility, and linear facility, and linear facility for walking. The second phase analysis tested the fit of the causal models for satisfaction with recreational facilities to the data and identified statistically significant causal linkage among overall satisfaction with Taejong-Dae recreational complex, other endogenous factors and exogenous variables. Overall fits of both causal models were very good. Among endogenous factors, facility for repose and relaxation. linear facility for walking, active recreation facility, facility for convenience and maintenance were identified as having significant effects on overall satisfaction. Exogenous variables which have significant effects on endogenous variables wer also identified. These significant relationships indicate important factors and variables that should be considered in planning and development of the recreational complex. On the basis of these significant causal relationships, implications for planning and the delovepment of Taejong-Dae recreational complex were suggested.

• 한국방재학회 논문집
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• 제10권4호
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• pp.81-88
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• 2010

최근 들어 기상 이변에 따라 단시간 동안에 특정 소유역에 집중하는 호우 또는 초과우량에 의한 국지성 돌발홍수가 빈번히 발생함에 따라, 이로 인한 인명과 재산의 상당한 위험과 손실은 전 세계적인 것으로서 우리나라도 증가일로에 있다. 돌발홍수는 일반적으로 급경사 소유역에서 집중적인 강우에 의해 발생하여 빠른 유출과 토석류를 동반하기 때문에, 홍수피해를 대비하기 위한 사전 홍수예보시간이 부족할 정도로 급격히 빠른 홍수의 특성을 보인다. 본 연구의 목적은 대상유역의 확률강우량으로부터 돌발홍수지수(flash flood index, FFI)를 산정하여 돌발홍수의 심각성 정도를 정량적으로 분석하고자 한다. 특히 미계측 유역하천에서의 지역 홍수예 경보를 위한 기초자료를 제공할 수 있도록, 대상유역에 대하여 상대적인 돌발홍수심도를 제시할 수 있는 FFI-D-F(돌발홍수지수-지속시간-빈도) 관계곡선을 개발하였다. 또한 FFI-D-F 관계곡선은 현존 및 계획 방재시설물의 돌발홍수 대응능력 및 잔여홍수위험 평가에 활용될 수 있을 것으로 기대된다.

• 한국항행학회논문지
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• 제21권2호
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• pp.155-162
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• 2017

최근 국내에서 항공 관련 안전필수시스템들이 개발되었지만 이들 완성품들은 규정된 요구사항들을 충족시키지 못하여 실용화 또는 상용화 되지 못하였다. 현대 항공 기술의 복잡도가 높아짐에 따라 기존의 검증 및 확인 기술로는 시스템에 잠재된 리스크를 식별하고 줄이는데 어려움이 많다. 이러한 단점들을 극복하기 위해 선진국에서는 독립적 검증 및 확인이라는 새로운 기법에 관심이 모아지고 있다. 이 독립적 검증 및 확인의 효과도에 관한 학술적 연구는 국내에는 전무하고, 국외에서 조차도 매우 희소하게 수행되고 있다. 따라서 본 논문에서는 항공선진기관에서 수행한 항공 안전필수시스템에 대한 독립적 검증 및 확인의 응용 연구들을 조사하여 사업에 미치는 여러 가지 효과들을 분석해 본 결과, IV&V는 조기 오류 검출율을 높이고, 내재된 리스크도 조기에 완화하며, 개발 수명주기 후반에 나타나는 재작업 확률을 줄여서 개발 일정 및 비용의 증가를 획기적으로 막아주는 것으로 나타났다.