• The Journal of KAIRB
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• v.1 no.1
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• pp.5-21
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• 2019

Purpose: Institutional review board (IRB) classifies risks of clinical trials into less than minimal risk, minor increase over minimal risk, and more than minimal risk. Based on classification and evaluation for risk, IRB decides whether permitting consent exemption or asking additional protection for clinical research subject or not. The purpose of this study is to analyze how IRB members evaluate minimal risk by sending questionnaire survey with 12 predetermined scenarios. Methods: IRB members and researchers (pediatrician, gastroenterologist, neurologist, and neurosurgeon) in 11 different hospitals were asked to answer survey questions via email or online. We analyzed the differences of answers among several subgroups in each predetermined scenarios. Result: Responders were 212 personnel(110 researchers and 102 IRB members) from 11 centers. There were significant differences between IRB members and researchers in response such as blood sampling, skin prick test, one time catheterization in a girl, spinal tapping in child, non-enhance MRI in child, non-enhance MRI with chrolal hydrate in a child, spinal tapping without anesthesia in adult, bioequivalence test, gastric endoscopy, and non-enhance CT. significant differences between medical IRB members and non-medical members were also revealed in one time catheterization in a girl, spinal tapping in a child, non-enhance MRI in a child, bioequivalence test. Depending on researchers' department, they responded differently in several questionnaires as well. Conclusions: We have found that IRB members and researchers evaluate the risks differently. Researchers compared to IRB members, medical IRB members compared to non-medical members answered less than minimal risk in many cases. In assessing and evaluating the risks associated with the study, medical IRB members answered predetermined scenarios as less dangerous compared to non-medical IRB members. Difference among researchers where also revealed significantly. Researchers answered predetermined scenarios as less dangerous compare to other department researchers, especially in predetermined scenarios containing procedures they are familiar with.

• Journal of the Korea Safety Management & Science
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• v.14 no.1
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• pp.225-233
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• 2012

The research discusses interrelationship of structural and reliability importance measures which used in the probabilistic safety assessment. The most frequently used component importance measures, such as Birnbaum's Importance (BI), Risk Reduction (RR), Risk Reduction Worth (RRW), RA (Risk Achievement), Risk Achievement Worth (RAW), Fussel Vesely (FV) and Critically Importance (CI) can be derived from two structure importance measures that are developed based on the size and the number of Minimal Path Set (MPS) and Minimal Cut Set (MCS). In order to show an effectiveness of importance measures which is developed in this paper, the three representative functional structures, such as series-parallel, k out of n and bridge are used to compare with Birnbaum's Importance measure. In addition, the study presents the implementation examples of Total Productive Maintenance (TPM) metrics and alternating renewal process models with exponential distribution to calculate the availability and unavailability of component facility for improving system performances. System state structure functions in terms of component states can be converted into the system availability (unavailability) functions by substituting the component reliabilities (unavailabilities) for the component states. The applicable examples are presented in order to help the understanding of practitioners.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.2
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• pp.45-57
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• 2004

The purpose of this paper is studying the valuation of option prices in Incomplete markets. A market is said to be incomplete if the given traded assets are insufficient to hedge a contingent claim. This situation occurs, for example, when the underlying stock process follows jump-diffusion processes. Due to the jump part, it is impossible to construct a hedging portfolio with stocks and riskless assets. Contrary to the case of a complete market in which only one equivalent martingale measure exists, there are infinite numbers of equivalent martingale measures in an incomplete market. Our research here is focusing on risk minimizing hedging strategy and its associated minimal martingale measure under the jump-diffusion processes. Based on this risk minimizing hedging strategy, we characterize the dynamics of a risky asset and derive the valuation formula for an option price. The main contribution of this paper is to obtain an analytical formula for a European option price under the jump-diffusion processes using the minimal martingale measure.

• The Journal of KAIRB
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• v.4 no.2
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• pp.36-41
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• 2022

Purpose: The purpose of this study is to evaluate how university hospital Institutional Review Boards (IRBs) in Korea classify risk when reviewing clinical trial protocols. Methods: IRB experts (IRB chairman, vice chairman, IRB administrator) in the university hospitals obtaining a Human research protection program (HRPP) or IRB accreditation in Korea were asked to fill out the Google Survey from September 1, 2020 to October 10, 2020. Result: Among the 23 responder hospitals, 8 were accredited by the American Association for Human Research Protection Program (AAHRPP) and 8 were accredited by the HRPP of Ministry of Food and Drug Safety (MFDS). Seven were accredited by Forum for Ethical Review Committees in Asia and the Western Pacific or Korea National Institution for Bioethics Policy. Thirteen of 23 hospitals (56.5%) had 4 levels (less than minimal, low, moderate, high risk), 4 hospitals had 3 levels (less than, slightly over, over than minimal risk), 1 hospital had 5 levels (4 levels plus required data safety monitoring board), and 1 hospital had 2 levels (less than, over than minimal risk) risk classification system. Thirteen of 23 hospitals (56.5%) had difficulty classifying the risk levels of research protocols. Fourteen hospitals (60.9%) responded that different standards among hospitals for risk level determination associated with clinical trials will affect the subject protection. Six hospitals (26.1%) responded that it will not. Three hospitals (13.0%) responded that it will affect the beginning of the clinical trial. To resolve differences in standards between hospitals, 14 hospitals (60.9%) responded that either the Korean Association of IRB or MFDS needs to provide a guideline for risk level determination in clinical trials: 5 hospitals (21.7%) responded education for IRB members and researchers is needed; 3 hospitals (13.0%) responded that difference among institutions needs to be acknowledged; and 1 hospital (4.3%) responded that there needs to be communication among IRB, investigator, and sponsor. Conclusion: After conducting a nationwide survey on how IRB in university hospital determines risk during review of clinical trials, it is reasonable to use 4-level risk classification (less than minimal, low, moderate, high risk); the most utilized method among hospitals. Moreover, personal information and conflict of interest associated with clinical trials have to be considered when reviewing clinical trial protocols.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.107-110
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• 1996

Continuing advances in the formulation and solution of risk-sensitive control problems have reached a point at which this topic is becoming one of the more intriguing modern paradigms of feedback thought. Despite a prevailing atmosphere of close scrutiny of theoretical studies, the risk-sensitive body of knowledge is growing. Moreover, from the point of view of applications, the detailed properties of risk-sensitive design are only now beginning to be worked out. Accordingly, the time seems to be right for a survey of the historical underpinnings of the subject. This paper addresses the beginnings and the evolution, over the first quarter-century or so, and points out the close relationship of the topic with the notion of optimal cost cumulates, in particular the cost variance. It is to be expected that, in due course, some duality will appear between these notions and those in estimation and filtering. The purpose of this document is to help to lay a framework for that eventuality.

• The Pure and Applied Mathematics
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• v.25 no.1
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• pp.1-5
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• 2018

It is proved that 'maximum' is actually attained in the following risk measure representation $${\rho}_m(X)={max \atop Q{\in}Q_m}E_Q[-X]$$.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.119-130
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• 2023

Among the various elements of probabilistic safety assessment (PSA), human failure events (HFEs) and their dependencies are major contributors to the quantification of risk of a nuclear power plant. Currently, the dependency among HFEs is reflected using a post-processing method in PSA, wherein several drawbacks, such as limited propagation of minimal cutsets through the fault tree and improper truncation of minimal cutsets exist. In this paper, we propose a method to model the HFE dependency directly in a fault tree using the if-then-else logic. The proposed method proved to be equivalent to the conventional post-processing method while addressing the drawbacks of the latter. We also developed a software tool to facilitate the implementation of the proposed method considering the need for modeling the dependency between multiple HFEs. We applied the proposed method to a specific case to demonstrate the drawbacks of the conventional post-processing method and the advantages of the proposed method. When applied appropriately under specific conditions, the direct fault-tree modeling of HFE dependency enhances the accuracy of the risk quantification and facilitates the analysis of minimal cutsets.

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1255-1265
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• 2018

The need for a PSA (Probabilistic Safety Assessment) for a multi-unit at a site is growing after the Fukushima accident. Many countries have been studying issues regarding a multi-unit PSA. One of these issues is the problem of many combinations of accident sequences in a multi-unit PSA. This paper deals with the methodology and software to quantify a PSA scenarios for a multi-unit site. Two approaches are developed to quantify a multi-unit PSA. One is to use a minimal cut set approach, and the other is to use a Monte Carlo approach.

• Korean Journal of Health Education and Promotion
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• v.31 no.4
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• pp.37-49
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• 2014

Objectives: The aim of this study was to evaluate the effects of a lifestyle modification program for Korean adults with cardiovascular disease risk factors on their health behaviors and health status. Methods: A total of 448 adults with abdominal obesity and additional cardiovascular disease risk factors(high blood pressure, low HDL-cholesterol, high triglyceride or high blood glucose) were randomly assigned to either an intensive intervention group (IIG, n=216) or a minimal intervention group(MIG, n=232). Participants in the IIG received lifestyle modification program which consisted of health counseling with nutrition assessment, health booklet and health diary, while those in MIG received minimal information. Results: The participants in the IIG significantly improved dietary habits(p<.05), retrained eating(p<.001), external eating(p<.01) behaviors, leisure time physical activity(p<.05), dietary self-efficacy(p<.01), exercise self-efficacy(p<.01) and MetS score(p<.001) after 3 months. In addition, the participants in the IIG showed more improvement in dietary habits(p<.05) compared with those in the MIG. Conclusion: The lifestyle modification program was effective in improving some health behaviors, behavioral determinants and cardiovascular risk factors for a short term.

• Journal of Medicine and Life Science
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• v.19 no.3
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• pp.125-129
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• 2022

Patients with nephrotic syndrome (NS) are generally known to be at greater risk for thrombosis, with arterial thrombosis-related complications being relatively rare compared to venous thrombosis-related complications. This report describes a 46-year-old male with historically proven minimal change disease (MCD) complicated by acute aortoiliac thrombosis. He had been diagnosed with MCD 8 months previously and was treated successfully with steroids. He was prescribed a second course of high-dose steroids (prednisolone 1 mg/kg/day) due to a relapse of MCD at the outpatient clinic 8 days before the emergency department visit. The patient presented with severe pain in both lower limbs and was diagnosed with aortoiliac thrombosis that developed during high-dose steroid treatment. He subsequently underwent surgical thromboembolectomy. Hypoalbuminemia has the strongest association with the risk of thromboembolism. According to international clinical practice guidelines, anticoagulant therapy is recommended when serum albumin is ≤2-2.5 g/dL. However, as serum albumin levels may be relatively high in the early phase of NS, as in this case report, an individualized anticoagulation strategy for each patient should be considered, regardless of serum albumin levels.