• 한국경영과학회지
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• 제40권4호
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• pp.35-48
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• 2015

We analyze the systemic risk based on the information flows using the variance decomposition, DebtRank methods, and the Industry Sector Indices during 2001. 01 to 2015. 08. Using the KOSPI stock market as our setting, we find that (i) the systemic risk calculated by information flows of variance decompositions method shows strong positive relations with the market volatility, (ii) the magnitude of systemic risk measured from the information flows network by DebtRank method increases after the subprime financial crisis.

• Genomics & Informatics
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• 제5권3호
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• pp.95-101
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• 2007

In this paper, we consider the variable selection methods in the Cox model when a large number of gene expression levels are involved with survival time. Deciding which genes are associated with survival time has been a challenging problem because of the large number of genes and relatively small sample size (n<

• 보건교육건강증진학회지
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• 제30권5호
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• pp.201-210
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• 2013

Objectives: The public relies on the news media to understand health risks. To examine the surveillance function of Korean health journalism, this study compared the rank-order of the 10 most frequently diagnosed cancers with that of the 10 cancers most frequently covered by three major Korean newspapers. Methods: News stories published between 1999 and 2010 by the Chosun-Ilbo, Joong-Ang-Ilbo, and Dong-A-Ilbo were examined. Data on cancer incidence were collected using the epidemiological data published by a governmental public health institution. To compare the level of the crude rates and the amount of news coverage, rank-order correlation tests and regression analyses were employed. Results: A reduction in the rank-ordered correlation coefficient was observed despite an increase in the overall number of cancer news stories released. The significance of the correlation disappeared after 2006. The big difference of the rank order between the crude rate and the amount of news coverage was observed in the cancer of breast, uteri, thyroid, and gallbladder/biliary. Finally, the three newspapers did not follow the amount change in stomach, lung, liver, and uterine cervix cancer. The four cancers' rank orders of crude rate were lowering, signifying a reduction of the comparative dangerousness of the four cancers. Conclusions: The news media's customization of news content and the negative bias in journalism are suggested as possible influences on the news media's inaccurate representation of cancer risk.

• 한국환경보건학회지
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• 제42권6호
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• pp.419-429
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• 2016

Objectives: According to the new Chemical Control Act from the Korean Ministry of Environment (2014-259), workers handling hazardous chemicals should wear personal protective equipment (PPE). However the act simply states in basic phrases that every worker handling one or more of the 69 listed chemicals should wear PPE and does not consider the unique hazard characteristics of chemicals and work types. The main purpose of this study is to provide basic data to revise the act to suit particular work processes and situations. Methods: The hazard rank of the substances was classified based on hazardous characteristics such as LC50 and vapor pressure using matrix analysis. The workplace exposure risk of the substances was also determined through a matrix analysis based on the previously determined hazard ranks and the demands of manual handling together with the likelihood of accident frequency of the operation combined with the exposure of workers during spill accidents. Results: To meet the demands for developing subsequent guidelines for the risk-based application of PPE in hazardous workplaces, this study sorted the 69 listed chemicals into five hazardous categories based on their LC50 and vapor pressures, and also assigned exposure categories according to exposure vulnerability for various types of work which are frequently performed throughout the life cycle of the chemicals. Conclusion: In the next study, an exposure risk matrix will be produced using the hazard rank of chemicals and workplace exposure risk, and then PPE will be selected to suit the categories of the exposure risk matrix.

• 응용통계연구
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• 제28권2호
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• pp.241-250
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• 2015

경시적 자료 연구의 중요한 주제 중의 하나는 시간이 지남에 따라 개인의 건강 상태가 어떻게 변하는지를 추적하는 확률이다. 질병의 상태를 시간의 흐름에 따라 추적하는 것은 장기간에 걸친 임상적 관찰 연구의 계획과 분석, 그리고 질병의 예방과 치료에 중요한 의미를 지닌다. 본 논문에서는 두 다른 시점에서 각 개인의 건강 상태에 대한 조건부 확률을 추정해내는 순위 추적 확률에 대하여 연구하였다. 순위 추적 확률과 순위 추적 확률비를 추정하기 위하여 선형 혼합 효과 모형을 고려하였다. 본 논문의 방법은 아동을 대상으로 심혈관계 질환의 위험요인을 연구하는 역학 자료에 적용되었다.

• 한국식품위생안전성학회지
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• 제24권3호
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• pp.200-203
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• 2009

우리나라 식품공전상에 수록된 식품군 및 식품유형에 대한 위해순위(risk ranking) 결정은 식품안전관련 위생관리 우선순위 적용 등에 있어 중요한 수단으로 작용할 수 있다. 하지만 세계적인 관심의 증대에도 불구하고 아직까지 국내에서는 체계적으로 수행된 적이 없었다. 본 연구는 식품공전에 포함되어 있는 101개의 식품유형에 대하여 상대적인 위해 순위를 결정하였다. 상대위해도는 노출평가, 심각성평가 및 섭취량 추정부분으로 구성된 위해평가모델을 이용하였다. 추정결과, 즉석섭취식품(RTE)이 가장 높은 위해수준을 나타내었고, 다음이 어육가공품, 빵류 등의 순으로 나타났다. 이러한 식품공전상의 식품유형에 대한 과학적인 위해순위 결과는 식품안전에 있어 가장 많은 영향을 미치는 식품과 이들 식품에 대한 관리목표를 설정하는데 크게 활용될 수 있을 것이다.

• 대한수학회지
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• 제61권3호
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• pp.427-444
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• 2024

The matrix completion problem is to predict missing entries of a data matrix using the low-rank approximation of the observed entries. Typical approaches to matrix completion problem often rely on thresholding the singular values of the data matrix. However, these approaches have some limitations. In particular, a discontinuity is present near the thresholding value, and the thresholding value must be manually selected. To overcome these difficulties, we propose a shrinkage and thresholding function that smoothly thresholds the singular values to obtain more accurate and robust estimation of the data matrix. Furthermore, the proposed function is differentiable so that the thresholding values can be adaptively calculated during the iterations using Stein unbiased risk estimate. The experimental results demonstrate that the proposed algorithm yields a more accurate estimation with a faster execution than other matrix completion algorithms in image inpainting problems.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.555-558
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• 2003

The Choquet-Stieltjes integral is defined. It is shown that the Choquet -Stieltjes integral is rep-resented by a Choquet integral. As an application of the theorem above, it is shown that Choquet expected utility model for decision under uncertainty and rank dependent utility model for decision under .risk are respectively same as their simplified version.

• Journal of Information Technology Applications and Management
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• 제25권1호
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• pp.67-85
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• 2018

We propose a noise reduced risk aversion index for measuring risk aversion through a laboratory experiment to overcome disadvantages of the multiple pricing list format developed by Holt and Laury (2002). We use randomized multiple list choices with coarser classification and reward weighting, supplement the rank of risk aversion with extra individual characteristics of risk attitude, and construct an index of risk aversion by standardizing the risk aversion ranking with quantile normalization. Our method reduces multiple switching problems that noisy decision makers mistakenly commit in experimental approaches, so that it is free of the framing effect which severely occurred in the HL. Furthermore, the index doesn't utilize any specific utility function or probability weighting, which allows researcher to hold the independence axiom. Since our noise reduced index of risk aversion has many good traits, it is widely used and applied to reveal fundamental characteristics of risk-related behaviors in economics and finance regardless of experimental environment.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.279-290
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• 2010

Technical countermeasures against debris flow should be established upon the risk level of the target location. Risk of debris flow should consider the hazard imposed by debris flow and vulnerability of the facilities to debris flow. In this research, we have defined the target location for risk evaluation and suggested scoring method of hazard of debris flow and vulnerability of road to debris flow. By defining risk rank into 6 categories in terms of possibility of damage during rainfall and using the risk scores of 46 debris flow cases, we have suggested risk ranking matrix. The method can be used in ranking the drainage basin adjacent to road by simply determining the hazard with vulnerability score and can be used for planning the debris flow countermeasures.