• Title/Summary/Keyword: Target level of safety

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Load & Resistance Factors Calibration for Limit State Design of Non-Perforated Caisson Breakwater (직립무공케이슨방파제 한계상태설계를 위한 하중저항계수 보정)

  • Kim, Dong Hyawn
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.6
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    • pp.351-355
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    • 2019
  • Load resistance factors for the limit state design of vertical caisson breakwaters are presented. Reliability analysis of 16 breakwaters in nationwide ports was conducted to calculate the partial safety factors and they were converted into load and resistance factors. The final load resistance factor was calibrated by applying the optimization technique to the individually calculated load resistance factors. Finally, the breakwater was redesigned using the optimal load resistance factor and verified whether the target level was met. The load resistance factor according to the change of the target reliability level is presented to facilitate the limit state design of breakwater.

Evaluation of the Contributions of Individual Finger Forces in Various Submaximal Grip Force Exertion Levels

  • Kong, Yong-Ku;Lee, Inseok;Lee, Juhee;Lee, Kyungsuk;Choi, Kyeong-Hee
    • Journal of the Ergonomics Society of Korea
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    • v.35 no.5
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    • pp.361-370
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    • 2016
  • Objective:The aim of this study is to evaluate contributions of individual finger forces associated with various levels of submaximal voluntary contraction tasks. Background: Although many researches for individual finger force have been conducted, most of the studies mainly focus on the maximal voluntary contraction. However, Information concerning individual finger forces during submaximal voluntary contraction is also very important for developing biomechanical models and for designing hand tools, work equipment, hand prostheses and robotic hands. Due to these reasons, studies on the contribution of individual finger force in submaximal grip force exertions should be fully considered. Method: A total of 60 healthy adults without any musculoskeletal disorders in the upper arms participated in this study. The young group (mean: 23.7 yrs) consisted of 30 healthy adults (15 males and 15 females), and the elderly group (mean: 75.2 yrs) was also composed of 30 participants (15 males and 15 females). A multi-Finger Force Measurement (MFFM) System developed by Kim and Kong (2008) was applied in order to measure total grip strength and individual finger forces. The participants were asked to exert a grip force attempting to minimize the difference between the target force and their exerted force for eight different target forces (5, 15, 25, 35, 45, 55, 65, and 75% MVCs). These target forces based on the maximum voluntary contraction, which were obtained from each participant, were randomly assigned in this study. Results: The contributions of middle and ring fingers to the total grip force represented an increasing trend as the target force level increased. On the other hand, the contributions of index and little fingers showed a decreasing trend as the target force level increased. In particular, Index finger exerted the largest contribution to the total grip force, followed by middle, ring and little fingers in the case of the smallest target force level (5% MVC), whereas middle finger showed the largest contribution, followed by ring, index and little fingers at the largest target force levels (65 and 75% MVCs). Conclusion: Each individual finger showed a different contribution pattern to the grip force exertion. As the target force level increase from 5 to 75% MVC, the contributions of middle and ring fingers showed an increasing trend, whereas the contributions of index and little fingers represented a decreasing trend in this study. Application: The results of this study can be useful information when designing robotic hands, hand tools and work equipment. Such information would be also useful when abnormal hand functions are evaluated.

A Study on the PHA of ATP Equipment for the Korean Tilting Train (한국형 틸팅열차 ATP장치 예비위험원분석에 관한 연구)

  • Shin, Duc-Ko;Baek, Jong-Hyen;Lee, Kang-Mi;Kim, Yong-Kyu
    • Proceedings of the KSR Conference
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    • 2009.05a
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    • pp.1959-1962
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    • 2009
  • In this paper, we derive the hazard which is a criterion of safety assurance by PHA for the ATP equipped in Korea Tilting Train. The ATP onboard equipment in Korea Tilting Train was introduced as ETCS Level l(which is ETCS specification). Also, the ATP trackside equipment was introduced as a ETCS SRS(System Requirement Specification) 2.2.2 and it has a target for commercial operation in 2009 late. In IEC 62278(EN50126), it recommend of PHA to derive a hazard of target system in concept establishment step and estimate if it can control as a tolerable level and then derive safety case to control the hazard by lifecycle. Therefore, we indicate the hazard using criterion of safety assurance by PHA using FRS (Functional Requirement Specification) 5.0. which is a upper criterion than SRS. The hazard of ATP onboard equipment derived in Korea Tilting Train will be able to use as ATP functional hazards of unified onboard equipment in G7 which is a multiple unit and preliminary hazards of ATP onboard equipment in NEL drived by Korail.

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Surveillance-based Risk Assessment Model between Urban Air Mobility and Obstacles (도심 항공 모빌리티와 장애물 간의 감시장비 기반 충돌 위험도 평가모형)

  • Kim, Dongsin;Lee, Keumjin
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.30 no.3
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    • pp.19-27
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    • 2022
  • Urban Air Mobility is expected to resolve some problems in urban transportation such as traffic congestion and air pollution. Various studies for a large-scale commercialization of UAM are being actively conducted. To that end, the UAM Traffic Management system aims at securing a safety and an efficiency of UAM operations. In this study, a risk assessment model is proposed to evaluate the risk of collision between a vehicle and surrounding obstacles. The proposed model is conceived from the past studies for determining a proper separation distance between parallel runways for their independent operations. The model calculates the risk that the surveillance system fails to meet a target level of safety for a given buffer zone size between a designed route and surrounding obstacles. The model is applied to one of the routes proposed in K-UAM roadmap to evaluate its performances.

A Study on the Method Improvement of the Integrated Railway Safety Audit System through the Analysis of Results (철도종합안전심사 결과 분석을 통한 효율적 심사방안 연구)

  • Song, Bo-Young;Song, Byeong-Ho;Oh, In-Tack
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.2503-2516
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    • 2011
  • According to Railway Safety Act, Korea Transportation Safety Authority (KOTSA) has been entrusted with 'Integrated Railroad Safety Audit (IRSA) and has implemented the safety audit to the railroad operation agencies such as Korea Railroad (KORAIL) and the railroad facility management organization such as the Korea Rail Network Authority (KR Network). The target of IRSA is to establish the effective rail safety management system and to raise the safety level of the railroad operation and facility agencies by checking synthetically their performance of safety duties with sincerity according to the Railway Safety Act. Even though newly introduced IRSA is conducted smoothly, it is necessary to study the methodology and criteria of the state's safety audit system. The purpose of this paper is to improve the efficiency of IRSA by the comparative research between IRSA and other similar safety audit system and to establish the consecutive improvement concept of IRSA. Second purpose is to confirm the effectiveness of IRSA by the analysis of the relationship between audit results and the safety level of the rail operation agencies.

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Estimation of Partial Safety Factors and Target Failure Probability Based on Cost Optimization of Rubble Mound Breakwaters (경사식 방파제의 비용 최적화에 기초한 부분안전계수 및 목표파괴확률 산정)

  • Kim, Seung-Woo;Suh, Kyung-Duck;Burcharth, Hans F.
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.3
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    • pp.191-201
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    • 2010
  • The breakwaters are designed by considering the cost optimization because a human risk is seldom considered. Most breakwaters, however, were constructed without considering the cost optimization. In this study, the optimum return period, target failure probability and the partial safety factors were evaluated by applying the cost optimization to the rubble mound breakwaters in Korea. The applied method was developed by Hans F. Burcharth and John D. Sorensen in relation to the PIANC Working Group 47. The optimum return period was determined as 50 years in many cases and was found as 100 years in the case of high real interest rate. Target failure probability was suggested by using the probabilities of failure corresponding to the optimum return period and those of reliability analysis of existing structures. The final target failure probability is about 60% for the initial limit state of the national design standard and then the overall safety factor is calculated as 1.09. It is required that the nominal diameter and weight of armor are respectively 9% and 30% larger than those of the existing design method. Moreover, partial safety factors considering the cost optimization were compared with those calculated by Level 2 analysis and a fairly good agreement was found between the two methods especially the failure probability less than 40%.

The Reasonable SIL Determination by LOPA for HIPS Design of Flare Stack (LOPA분석에 의한 Flare Stack용 HIPS의 합리적 SIL결정)

  • Park, Jinhyung;Park, Kyoshik
    • Proceedings of the Korean Society of Disaster Information Conference
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    • 2023.11a
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    • pp.221-221
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    • 2023
  • 1969년에 발간된 API521 1st edition에서는 Flare Load 저감용으로 적용되는 HIPS (High Integrity Protection System)는 모두 Pressure Safety Valve의 고장확률보다 낮은 SIL 3 (Safety Integrity Level)등급을 적용할 것을 요구하고 있다. Flare Stack 저감용 HIPS는 주로 압축기 출력압력상승, Reboiler Steam 과다주입, 전력공급중단냉각펌프고장 등에 의한 Flare 발생을 예방하기 위한 기능을 가진 SIF (Safety Instrumented Function)로 구성된다. 하지만 2007년도 발간된 API521 5th edition에서는 LOPA (Layer Of Protection Analysis) 분석을 통해 Target SIL을 도출하는 것으로 요구사항을 변경했다. 이에 따라 이번 연구에서는 Flare Load에 가장 큰 영향을 미치는 시나리오 중 대표적인 시나리오를 대상으로 HAZOP(Hazard and Operability Study)과 LOPA분석을 실시해서 Target SIL이 어떻게 도출되는지를 연구했다. Flare Stack에서 Flare를 발생시키는 대표적인 시나리오들에 대해 LOPA분석을 실시한 결과 압축기 출력압력상승은 SIL 2, Reboiler Steam 과다주입은 SIL 3, 전력공급중단은 SIL 0, 냉각펌프고장은 SIL 0로 모두가 SIL 3 가 나오지는 않았다. SIF 설계 시 Target SIL을 만족시키는 것도 중요하지만 운전 시 SIL 등급이 계속 유지되게 하지 위해 인적오류, 시스템적 고장, 하드웨어고장 등에 의해 SIF 기능불능화가 되는 것을 예방하기 위한 기능안전관리시스템 (FSMS)를 적용하는 것도 중요하다.

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2-Week repeated oral dose toxicity study of 1,4-dichlorobutane in rats (1,4-Dichlorobutane의 랫드 2주 반복경구투여독성시험)

  • Kim, Jong-Kyu;Lee, In-Chul;Kim, Sung-Hwan;Baek, Hyung-Seon;Bae, Jin-Sook;Song, Si-Whan;Kim, Jong-Choon;Chung, Yong-Hyun
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.23 no.1
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    • pp.1-10
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    • 2013
  • Objectives: The present study investigated the potential subacute toxicity of 1,4-dichlorobutane (1,4-DCB) by a 2-week repeated oral dose in male Sprague-Dawley rats. Materials and Methods: The test chemical was administered once daily by gavage to male rats at dose levels of 0, 74, 222, 667, and 2000 mg/kg/day for 2 weeks. All rats were sacrificed at the end of treatment period. During the test period, clinical signs, mortality, body weights, food and water consumption, urinalysis, hematology, serum biochemistry, gross findings, and organ weights were examined. Results: At 2000 mg/kg/day, treatment-related clinical signs, as evidenced by hypothermia, decreased locomotor activity, piloerection, lying on side, and prone position were observed. All the rats were found dead on test day 2. At 667 mg/kg/day, polyuria, suppressed body weight gain, food consumption, and spleen and thymus weights, and increased adrenal gland and liver weights were observed.Hematological and serum biochemical investigations revealed increases in the alanine aminotransferase, alkaline phosphataseand total bilirubinand decreases in the serum $Na^+$ level, white blood cell count and lymphocyte ratio. There were no treatment-related adverse effects in the 74 and 222 mg/kg/day groups. Conclusions: In the present experimental conditions, target organs were determined to be spleen, thymus,and liver. The no-observed-adverse-effect level was considered to be 222 mg/kg/day in male rats.

Validation of Availability, Maintainability and Safety for Subway Elevating Equipment (도시철도 승강설비의 가용성, 유지보수성 및 안전성 입증)

  • Lee, Hwan-Deok;Jung, Won
    • Journal of Applied Reliability
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    • v.16 no.4
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    • pp.272-279
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    • 2016
  • Purpose: In order to fulfill the RAMS (Reliability Availability Maintainability and Safety) requirements in Korean railway systems, specific target metrics should be measured and met the requirements when ordering a new system. This paper presents a procedure to predict and demonstrate the availability, maintainability and safety of subway elevators, escalators and PSD (platform screen doors) systems. Methods: The system manufacturer predicts availability and maintainability with lab and field tested data. After installation, availability and maintainability are demonstrated based on the actual operational data. The data was collected from the FRACAS (Failure Report and Corrective Action System). Results: Methods and process of assessing and analyzing the availability, maintainability and safety are presented for elevating services and PSD systems. The data obtained through the actual operation of the equipment is analyzed and maintained to predict the RAMS based on the component and system level failure data acquired. Conclusion: This study presented an application using IEC 62278 and operational data which can be used in the design and development stage to achieve the RAMS target value of the subway elevators, escalators and PSD systems.

A Study on the Improvement of Safety Management in the Workplaces Subject to Process Safety Management (PSM) (공정안전관리(PSM) 대상 사업장의 안전관리 개선 연구)

  • Jong-hun Park
    • Journal of the Society of Disaster Information
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    • v.19 no.3
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    • pp.490-497
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    • 2023
  • Purpose: Since the 1990s, Korea has been making various efforts to prevent serious industrial accidents, such as implementing a hazardous risk prevention plan and implementing a process safety management system, but a series of recent major industrial accidents have shown its limitations. Therefore, this study aims to present measures to improve safety management of PSM target workplaces. Method: Investigate previous studies and cases on improving safety management at workplaces subject to PSM, seek ways to improve safety management at workplaces subject to PSM based on existing safety management, and evaluate safety management system one of the causes of accidents. Therefore, a safety education program is established to increase employees' safety awareness and understanding, and to improve the safety level. Result: Measures such as establishing an organizational culture to improve safety management of PSM target workplaces, responding to disasters, systematic safety management, replacing and strengthening old facilities, and strengthening management's firm commitment to safety were presented. Conclusion: Through this study, it is meaningful to present a systematic plan to secure safety to reduce precious lives and damage, and it is expected to be useful in considering the direction of PSM improvement for each workplace.