• 한국안전학회지
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• 제35권1호
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• pp.62-69
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• 2020

Most people suffer from stress during day life because modernized society is very complex and changes fast. Because stress can affect to many kind of physiological phenomena it is even considered as a disease. Therefore, it should be detected earlier, then must be released. When a person is being stressed several bio-signals such as heart rate, etc. are changed. So, those can be detected using medical electronics techniques. In this paper, stress assessment system is studied using random forest algorithm based on heart rate, RR interval and Galvanic skin response. The random forest model was trained and tested using the data set obtained from the bio-signals. It is found that the stress assessment procedure developed in this paper is very useful.

• 한국안전학회지
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• 제14권2호
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• pp.155-162
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• 1999

reliability from components reliability. In this case, it assumes that components failure is mutually independent, but it may not true in real systems. In this study, the mean cost per unit time is computed as the ratio of mean life to the mean cost. The mean life is obtained by the reliability function under power rule model. The mean cost is obtained by the mathematical model based on the inspection interval. A heuristic method is proposed to determine the optimal number of redundant units and the optimal inspection interval to minimize the mean cost per unit time. The assumptions of this study are as following : First, in the load-sharing k-out-of-n:G system, total loads are applied to the system and shared by the operating components. Secondly, the number of failed components affects the failure rate of surviving components as a function of the total load applied. Finally, the relation between the load and the failure rate of surviving components is set by the power rule model. For the practical application of the above methods, numerical examples are presented.

• 한국안전학회지
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• 제14권3호
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• pp.25-32
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• 1999

This study has been performed to investigate the stress distribution around defects that behave as stress concentrators. Besides, the effect of stress interaction effects on the initiation of primary cracks were also investigated by rotary bending fatigue tests which were performed with specimens drilled micro surface defects and the stress distribution was analyzed using Finite Element Method. In addition, the stress interaction effects around defects and cracks were investigated by comparing the results of experiments and F.E.M. The results obtained are summarized as follows ; 1) Area which slip and micro cracks initiated at micro surface defects is between the maximum shear stress points and this area is over than ${\pm}30^{\circ}$ from the maximum stress point along the defect edge. 2) The stress interaction effect for the small size defect is larger than that of large size defect when the interval between them is near 3) Interval which there is no shear stress interaction effect analyzed by F.E.M. is larger than that of experimental results.

• 대한안전경영과학회지
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• 제9권2호
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• pp.215-233
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• 2007

Even though the ad hoc Shewhart methods remain controversial due to various mathematical flaws, there is little disagreement among researchers and practitioners when a set of process data has a skewness distribution. In the context and language of process control, the error related to the process data shows that time to signal increases when a control parameter shifts to a skewness direction. In real-world industrial settings, however, quality practitioners often need to consider a skewness distribution. To address this situation, we developed an enhanced design method to utilize advantages of the traditional attribute control chart and to overcome its associated shortcomings. The proposed design method minimizes bias, i.e., an average time to signal for the shift of process from the target value (ATS) curve, as well as it applies a variable sampling interval (VSI) method to an attribute control chart for detecting a process shift efficiently. The results of the factorial experiment obtained by various parameter circumstances show that the VSI c control chart using nearly unbiased ATS design provides the smallest decreasing rate in ATS among other charts for all experimental cases.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2003년도 춘계학술대회
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• pp.299-304
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• 2003

Manufacturing companies must possess a new type of production system with characteristics of reconfigurability, reusability and scalability (Dove 1995), i.e. an agile manufacturing system. Such system will allow flexibility not only in producing a variety of part, but also in changing the system itself, which is a difference form flexible manufacturing systems. A fundamental early step in the reconfiguring process for agile manufacturing system is to develop a model that adequately describes the proposed systems, in order to be able to study and evaluate the impact of the reconfiguring decision on the system performance, before its construction. Therefore, in this paper, an Object & Knowledge-based Interval Timed Petri-Net (OKITPN) approach is proposed.

• Communications for Statistical Applications and Methods
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• 제13권2호
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• pp.285-295
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• 2006

As more generic drugs become available, the quality, safety, and efficacy of generic drugs have become a public concern. Specifically, drug interchangeability among generic copies of the same brand-name drug is a safety concern. This research proposes a Bayesian method for assessing bioequivalence between two generic copies of the same brand-name drug from two independent $2{\times}2$ crossover design experiments. Uninformative priors are considered for general use and the posterior distribution of the difference of two generic drug effects is derived from which the highest probability density interval can be evaluated. Examples are presented for illustration.

• 자동차안전학회지
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• 제14권1호
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• pp.62-67
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• 2022

This study is to construct the simple estimating model for the HIC15 of the driver dummy using the frontal impact test results. Test results of 9 vehicles of Hyundai Sonata from the MY2002~MY2020 USNCAP are utilized for constructing the linear regression model. The average accelerations extracted from the vehicle crash pulses are handled as the main factors. The average accelerations of 10 ms interval within 0~100 ms are calculated from the crash pulse data of 9 vehicles. The present estimating model of the HIC15 using the average accelerations of 10 ms interval in the 0~80 ms range shows good agreement with the tested value within 2.4% maximum error.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1994년도 교수 연수회(환경)
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• pp.651-657
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• 1994

To assess quantitatively the association between benzene exposure and leukemia, we examined the mortality rate of a cohort with occupational exposure to benzene. Cumulative exposure for each cohort member was estimated from historical air-sampling data and, when no sampling data existed, from interpolation on the basis of existing data. The overall standardized mortality ratio (a measure of relative risk multiplied by 100) for leukemia was 337 (95 percent confidence interval, 154 to 641), and that for multiple myeloma was 409 (95 percent confidence interval, 110 to 1047). With stratification according to levels of cumulative exposure, the standardized mortality ratios for leukemia increased from 109 to 322, 1186, and 6637 with increases in cumulative benzene exposure from less than 40 parts per million-years (ppm-years), to 40 to 199, 200 to 399, and 400 or more. respectively. A cumulative benzene exposure of 400 ppm years is equivalent to a mean annual exposure of 10 ppm over a 40-year working lifetime; 10 ppm is the currently enforceable standard in the United States for occupational exposure to benzene. To examine the shape of the exposure-response relation, we performed a conditional logistic-regression analysis, in which 10 controls were matched to each cohort member with leukemia. From this model, it can be calculated that protection from benzene induced leukemia would increase exponentially with any reduction in the permissible exposure limit.

• Toxicological Research
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• 제22권2호
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• pp.109-116
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• 2006

Safety pharmacology studies are conducted to investigated the potential undesirable pharmacodynamic effects of a substance on physiological functions in relation to exposure in the therapeutic range and above. In the International Conference on Harmonisation (ICH), the guideline 'S7A: Safety Pharmacology Studies for Human Pharmaceuticals' has been developed and reached Step 5 of the ICH process in 2001. Now the Korea Food and Drug Administration (KFDA) are going to transfer 'The Guideline for General Pharmacology' into 'The Guideline for Safety Pharmacology'. Safety pharmacology studies should be performed in compliance with Good Laboratory Practice (GLP). Thus, the present paper reviews the Japanese GLP guidelines for pharmaceuticals to help the conduct and inspection of safety pharmacology studies in compliance with GLP. We also reviewed the ICH guidelines 'S7B revised : The Nonclinical Evaluation of the Potential for Delayed Ventricular Repolarization (QT Interval Prolongation) by Human Pharmaceuticals' and 'E14 : The Clinical Evaluation of QT/QTc Interval Prolongation and Proarrhythmic Potential for Non-antiarrhythmic Drugs' to apply our drug approval systems.

• 한국ITS학회 논문지
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• 제19권3호
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• pp.14-27
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• 2020

우리나라 교통사고 사망자 중 보행자 사망이 높은 비율을 차지하고 있어, 정책적으로 보행안전에 대한 관심이 높아지고 있다. 하지만 보행신호시간 계획의 경우 보행 편의 및 신호주기를 고려하지 않고 횡단보도 길이를 기준으로 보행신호시간을 적용하다 보니, 신호기가 설치된 폭이 좁은 부도로 횡단보도의 경우, 횡단거리에 비해 상대적으로 보행대기시간이 길어 보행자의 무단횡단을 유발하고 있다. 본 연구에서는 신호기가 설치된 부도로 횡단보도 중 불합리한 신호시간 계획으로 인해 보행자의 무단횡단이 많은 교차로를 대상으로 보행신호를 1주기 2회 부여하고 신호체계에 따른 운영적·안전적 효과를 정량적, 정성적으로 비교 분석하였다. 그 결과, 무단횡단과 보행대기시간이 감소하는 것으로 나타났으며, 보행신호시간 적용간격이 짧을수록 무단횡단은 감소하는 것으로 분석되었다. 다만, 보행자 노출에 따른 차량 상충위험이 있어 보행신호 1주기 2회 부여 운영에 대한 안전성 확대 방안을 제시하였다.