• Fire Science and Engineering
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• v.20 no.2 s.62
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• pp.8-13
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• 2006

Numerical simulations were carried out for a fire in a clean room to confirm needs of a smoke control system and a sprinkler system, and to investigate a possible smoke spread-out. For a 1 MW methanol fire in a space of $39m{\times}13m$ floor and 4 m high, smoke spread-out was scrutinized for failure of the sprinkler system and/or the smoke control system. It was shown that the smoke control system removes smoke safely without the sprinkler system and that the sprinkler system is required to suppress smoke generation and spread of the fire, and to remove the smoke quickly. It was also confirmed that highly reliable sprinkler heads and automatic fire detection system are required for the sprinkler and smoke control systems.

• Journal of Convergence for Information Technology
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• v.8 no.2
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• pp.157-162
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• 2018

The purpose of this study is to evaluate the level of trust by financial consumers and attempt to investigate the determinants that influence consumer trust in internet-only banks. For this aim, I conducted an empirical study and the survey results was used to test a structural equation model that analyzed the financial consumer trust and estimated the level of trust for internet-only banks. As a result of the analysis, the three most effective determinants of trust were security, convenience and benefit. Also, the level of financial consumer trust for the internet-only banks, based on the three factors, was later extended to relationship commitment such as renewal and recommendation intentions. Therefore, Internet-only banks need to focus on promoting their trust more effectively for future sustainable growth.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.280-282
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• 2010

위기대응 매뉴얼은 지진, 태풍 등 상황에 적절하게 적용되며 신뢰성 있게 작동한다는 것이 보장되어야 한다. 따라서 위기대응 매뉴얼의 검증은 필수적이며, 이를 위해 본 논문에서는 정형기법 도구인 Statemate를 이용한 명세, 검증 및 신뢰성 개선방안을 제시한다. 모델체킹을 통해서 매뉴얼 사용자들의 임의적인 판단을 일의킬 수 있는 Non-Determinism과 대응 매뉴얼이 달성하고자 하는 목표의 도달여부에 대해 검증을 수행할 수 있으며, 이외에도 사용자가 원하는 검증 속성을 Temporal Logic으로 작성해서 검증할 수 있다. 또한 도구에서 지원하는 시뮬레이션을 통해 제한적이지만 조치내용의 적절성 여부와 추가적으로 발생 가능한 트리거를 찾음으로써 위기대응 매뉴얼의 신뢰성을 향상시킬 수 있다.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.2
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• pp.225-230
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• 2017

To generate mechanical movements in one-shot devices such as missiles and space launch vehicles, pyrotechnic mechanical device(PMD) such as pin pullers using pyrotechnic charge has been widely used. Reliability prediction of pin pullers is crucial to successfully execute target missions for the one-shot devices. Because the pin pullers require destructive tests to evaluate their reliability, one would need about 3,000 samples of success to guarantee a reliability of 99.9 % with a confidence level of 95 %. This paper suggests the application of a probit model using the charge amount as a functional parameter for estimation of functional reliability of pin puller. To guarantee target reliability, we propose estimation methods of the lower bound of functional reliability by applying the probit model. Given lower bound of functional reliability, we quantitatively show that the optimum amount of charge increases as the number of samples decreases. Along with a variety of simulations the validity of our new model via real test results is confirmed.

• Journal of the KSME
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• v.26 no.1
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• pp.15-23
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• 1986

부품의 특성(수명)에 대해서 그 통계적 처리방법을 알아보았다. 어떤 장비나 부품의 신뢰성은 주어진 운용조건에서 의도하는 사용기간 중에 의도한 목적에 만족스럽게 작동할 확률로서 기계, 전기, 산업공학 등의 여러 전문분야의 지식이 필요하다. 또한 주어진 환경에서 장비설계 및 인 간공학적인 제 원칙을 종합하여 최소한의 비용으로 시스템(system)의 가용도(가용도)를 높이며 부품 수명의 정확한 추정을 통해 현재 상태를 파악하여 기술수준을 올려야 하는 것이 우리의 과제일 것이다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.9
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• pp.717-724
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• 2020

We study the closing characteristics of a self-sustainable poppet valve which serves as a main oxidizer shut-off valve for liquid rocket engines. Numerical analysis for predicting closing transient responses are presented and the calculated results have been verified by a comparison with experimental data. The effective area of a pilot gas discharge system and the pressure distribution of passage flow around the valve moving part are shown to be main parameters in determining the closing characteristics for dry and cryogenic conditions, respectively. Moreover, it is presented that the passage flow pressure at the valve closing moment as well as the valve closing velocity can be effectively adjusted by the appropriate employment of the pilot gas.

• Fire Science and Engineering
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• v.34 no.4
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• pp.45-51
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• 2020

The aim of this study is to investigate the gas temperature and velocity during sprinkler activation considering the fire growth scenario based on the thermal response model of the sprinkler. The fire source is assumed to have time square fire growth scenarios with a maximum heat release rate of 3 MW. Eight types of standard and fast-response sprinkler heads with an operating temperature range of 65-105 ℃ and a response time index range of 25-171 m^1/2s^1/2 were adopted. The temperature difference between the gas stream and the sensing element of the sprinkler head decreased as the fire growth slowed down, and the RTI value decreased. The overall gas temperature and velocity conditions predicted using the FDS model at sprinkler activation were in reasonable agreement with those of standard test conditions of the sprinkler head response. However, the sprinkler head could be activated at lower limits of gas temperature and velocity under the current test conditions for a slowly growing fire scenario.

• Fire Science and Engineering
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• v.28 no.6
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• pp.58-61
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• 2014

Flame detectors has been used more than heat & smoke detector, because this is more effective to catch fire and ceiling height in spite of high price. For upgrade to flame detector, Compare to national or abroad standard about performance test, sensitivity test, sectioning indoor or outdoor, after service and management. As a result, Europe and America have only sensitivity test, no have not operation test and sectioning indoor & outdoor. In performance test, action is put to focus to credit and durability, Not operation test is to be able to tune the sensitivity to match the environment of the site. Also, we need code about aftercare, quality assurance responsibility and implement special detector institution by Certificate Authority implement.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.7-10
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• 2011

본 논문에서는 스마트폰을 이용하여 차량을 원격시동 제어 및 관리하는 원격시동 관리 시스템을 제안한다. 이 시스템은 고가의 차량을 관리 및 제어하는 시스템인 만큼 작동의 신뢰성을 중요시 한다. 그래서 기존의 소형 리모콘 방식의 차량 원격시동 제어관리 시스템을 활용하여 시스템 작동의 신뢰도를 높였으며, 기존의 소형 리모콘 제어 환경에서 스마트폰으로 옮겨옴으로써, 기존의 입력 및 제어의 불편함을 해결하였다. 그리고 기존 존재하는 블루투스와 CDMA를 사용하는 차량 원격시동 제어 관리 시스템의 거리 및 속도, 비용 등의 문제점도 개선하였다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.119-120
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• 2020

In order to establish an evaluation method that can quantitatively evaluate the fire safety of existing buildings in Korea, a stochastic approach is needed to consider the extent of damage in the event of actual fire, along with the operation and installation of facilities. Accordingly, as a basic study for the establishment of fire safety assessment methods for buildings, this study aims to analyze the results of safety inspection and the degree of damage caused by the operation of fire doors and fire shutters in order to derive the reliability of fire doors and fire shutters. As a result, the results of inspection of fire shutters and fire doors and the results of operation using fire statisticians are as follows. As a result of the inspection, the positive rate of fire doors was about 82% and 98% of normal operation was derived from the fire investigation.