• 기술사
• /
• 제17권3호
• /
• pp.32-49
• /
• 1984

The East gate station area is 205M long and 24m deep which is located 13 meter in front of cultural treasure east gate. The area to be excavated by blasting is composed of granite rocks from 10M depth to 25M. Surface earth extends to up 10M depth. This job site has in involves heavy traffic congestion such as over 10,000 cars passing in rush hour where clossing No 1 lint of subway running 3 minitues head way. This east gate station construction is to be executed for the provent of the setting down of underground level and blasting vibration effects to cultural treasure east gate. Therefore, the caltural treasure committee approved this execution subject to the following condition. 1. Subway gelogical foundation and measured natural frequency 2. Execution of water tight wall 3. Sellection and test of damping material for wall and under rail 4. Measurement of monitoring system during the execution 5. Measurement of histogram system The above two projects was carried out by Dr. Kwang team in KAIST and prof, Han in Hanyang University under accadamic study contract. In the blasting work, for the pourpose of reduced vibration and low explosion velocity such as CCR, Kovex slurry. The 2nd, used electrical caps shall be delay cap and M/S caps in multi delay. The 3rd, drilling pattern is bench cut in open cut and applied control blasting in tunnelling and also shall drill anti-vibration holes as line drilling.

• Safety and Health at Work
• /
• 제11권3호
• /
• pp.322-334
• /
• 2020

Background: Spontaneous combustion of coal is one of the factors which causes direct or indirect gas and dust explosion, mine fire, the release of toxic gases, loss of reserve, and loss of miners' life. To avoid these incidents, the prediction of spontaneous combustion is essential. The safety of miner's in the mining field can be assured if the prediction of a coal fire is carried out at an early stage. Method: Adularya Underground Coal Mine which is fully mechanized with longwall mining method was selected as a case study area. The data collected for 2017, by sensors from ten gas monitoring stations were used for the simulation and prediction of a coal fire. In this study, the fuzzy logic model is used because of the uncertainties, nonlinearity, and imprecise variables in the data. For coal fire prediction, CO, O₂, N₂, and temperature were used as input variables whereas fire intensity was considered as the output variable.The simulation of the model is carried out using the Mamdani inference system and run by the Fuzzy Logic Toolbox in MATLAB. Results: The results showed that the fuzzy logic system is more reliable in predicting fire intensity with respect to uncertainties and nonlinearities of the data. It also indicates that the 1409 and 610/2B gas station points have a greater chance of causing spontaneous combustion and therefore require a precautional measure. Conclusion: The fuzzy logic model shows higher probability in predicting fire intensity with the simultaneous application of many variables compared with Graham's index.

• Journal of Radiation Protection and Research
• /
• 제41권2호
• /
• pp.117-121
• /
• 2016

Background: Definition and grouping of initiating events (IEs) are important basics for probabilistic safety assessment (PSA). An IE in a spent fuel reprocessing plant (SFRP) is an event that probably leads to the release of dangerous material to jeopardize workers, public and environment. The main difference between SFRPs and nuclear power plants (NPPs) is that hazard materials spread diffusely in a SFRP and radioactive material is just one kind of hazard material. Materials and Methods: Since the research on IEs for NPPs is in-depth around the world, there are several general methods to identify IEs: reference of lists in existence, review of experience feedback, qualitative analysis method, and deductive analysis method. While failure mode and effect analysis (FMEA) is an important qualitative analysis method, master logic diagram (MLD) method is the deductive analysis method. IE identification in SFRPs should be consulted with the experience of NPPs, however the differences between SFRPs and NPPs should be considered seriously. Results and Discussion: The plutonium uranium reduction extraction (Purex) process is adopted by the technics in a model reprocessing plant. The first extraction cycle (FEC) is the pivotal process in the Purex process. Whether the FEC can function safely and steadily would directly influence the production process of the whole plant-production quality. Important facilities of the FEC are installed in the equipment cells (ECs). In this work, IEs in the FEC process were identified and categorized by FMEA and MLD two methods, based on the fact that ECs are containments in the plant. Conclusion: The results show that only two ECs in the FEC do not need to be concerned particularly with safety problems, and criticality, fire and red oil explosion are IEs which should be emphatically analyzed. The results are accordant with the references.

• 대한기계학회논문집B
• /
• 제36권2호
• /
• pp.197-204
• /
• 2012

본 논문에서는 공기 중에서 높은 레이저 복사 조도에 따른 효과에 의해 발생되는 금속 플라즈마의 발달 과정에 대하여 레이저 펄스가 끝나는 이후로 쉐도우그래프(Shadowgraph) 가시화 방법을 이용하여 현상을 연구하였다. 따라서 레이저에 의한 데토네이션의 발생과 이를 일으키는 연소 과정 대한 연구가 진행되었다. 본 논문의 가장 중요한 점들은 높은 레이저 에너지에 의해 삭마 된 기체 상태의 알루미늄과 공기로부터의 산소와의 화학 반응의 진행을 관측했을 뿐만 아니라, 화학 반응 최종 산화물을 X선 회절 분석법(X-Ray Diffraction)을 통해 관측한 것이다. 그리고 레이저를 통해 유도된 화학적 반응 파와 공기 중에서의 알루미늄 분진 폭발의 데토네이션과의 양적인 평가를 유도하였다. 이러한 연구는 덩어리 상태의 금속 샘플에서 공기 중의 산소를 이용하여 데토네이션을 발생시키는 새로운 방법을 제시할 것으로 여겨진다.

• 한국안전학회지
• /
• 제33권1호
• /
• pp.66-72
• /
• 2018

This study analyses the types, related operations, facilities, and causes of chemical accidents in Korea based on the RISCAD classification taxonomy. In addition, human error analysis was carried out employing different human error classification criteria. Explosion and fire were major accident types, and nearly half of the accidents occurred during maintenance operation. In terms of related facility, storage devices and separators were the two most frequently involved ones. Results of the human error-based analysis showed that latent human errors in management level are involved in many accidents as well as active errors in the field level. Action errors related to unsafe behavior leads to accidents more often compared with the checking behavior. In particular, actions missed and inappropriate actions were major problems among the unsafe behaviors, which implicates that the compliance with the work procedure should be emphasized through education/training for the workers and the establishment of safety culture. According to the analysis of the causes of the human error, the frequency of skill-based mistakes leading to accidents were significantly lower than that of rule-based and knowledge based mistakes. However, there was limitation in the analysis of the root causes due to limited information in the accident investigation report. To solve this, it is suggested to adopt advanced accident investigation system including the establishment of independent organization and improvement in regulation.

• 한국가스학회지
• /
• 제15권2호
• /
• pp.57-62
• /
• 2011

DME(Dimethyl Ether)는 청정에너지원으로 친환경적이고, 다양한 용도로 사용될 수 있는 장점이 있다. 또한 DME는 LPG와 물리적 특성이 매우 유사하여, LPG와 혼합될 수 있고, DME-LPG 혼합연료는 기존 LPG 기반시설의 커다란 개조 없이 사용될 수 있다. 그러나 DME-LPG 혼합연료가 보급될 시 관련 설비 증가로 인해 중대사고 발생 가능성이 높다. 이에 본 연구에서는 DME-LPG 혼합연료에 따른 누출속도, 제트화재, 증기운 폭발, BLEVEs 및 화구 등의 피해예측을 실시하고, 이를 분석하여 DME-LPG 혼합연료의 위험성을 고찰하였다. 연구 결과, LPG와 DME 20 % 연료에서 제트화재, 증기운 폭발, BLEVEs 및 화구로 인한 피해예측 범위는 거의 유사한 것으로 나타났다.

• 대한인간공학회지
• /
• 제30권1호
• /
• pp.251-257
• /
• 2011

When designing a ship, ergonomic considerations are crucial when minimizing a navigator's fatigue due to the burden of work, and to appropriately operate the navigational equipment for each given situation by helping the operator to understand the surroundings as well as the physical functions of the ship. However, insufficient consideration of ergonomic elements in the actual design of ship Bridges is lowering the performance of safe navigation and allows for the possibility of operation or readout errors. Consequently, these errors lead to an increase in maritime accidents. Therefore, this study conducted a usability evaluation on the importance of and the usage frequency of navigational equipment, their influence on actual navigation, and the possibility of error upon operation or readout between training ship officers, to derive an optimized layout that includes the consideration of ergonomic factors for on-Bridge navigational equipment, which are currently arranged differently according to their type or size. The optimized layout of on-Bridge navigational equipment was carried out based on the evaluation results, using the Lingo program. Through the process of optimization, revised layouts of on-Bridge navigational equipments(control and display device) were suggested, considering emergency situations(ship collision, stranding, fire and explosion, sinking, etc.) during navigation.

• 대한전자공학회논문지TC
• /
• 제38권8호
• /
• pp.19-29
• /
• 2001

최근 인터넷 응용계층, 사용자수와 IP 백본망에서 트래픽의 폭발적인 증가는 전송망에 대해서 새로운 변화를 요구하고 있다. 이에 따라 대용량 WDM시스템들이 광범위하게 설치되고 있으며 이를 인터넷에 효율적으로 운영하기 위하여 IP/WDM을 구현하려는 노력이 진전되고 있다. WDM 전광망의 이용이득을 얻기 위해서는 IP 계층의 라우팅 프로토콜과 함께 전광망의 물리적인 망을 효율적으로 활용하게 해주는 논리적 토폴로지를 형성하고 광망을 제어하는 소프트웨어가 필요하다. 이를 위하여 WDM 전광망에서의 라우팅과 파장할당(RWA)을 효율적으로 수행할 수 있는 알고리듬이 필요하다. 본 논문에서는 WDM 전광망의 논리적인 토폴로지 형성을 위한 두 개의 직관적인 알고리듬을 구현하여 국내 백본망에 적용하였으며, 이들이 잘 동작함을 보였고 이들을 블록킹율등의 측면에서 비교분석하였다.

• 한국재난정보학회 논문집
• /
• 제12권3호
• /
• pp.273-278
• /
• 2016

본 연구에서는 인명구조용 근력지원장치 개발의 필요성, 목적, 개발방향을 설정하고 개발완료 예정인 근력지원장치가 적용가능한 재난현장을 분석하였다. 이를 위해 재난 및 안전관리기본법에 따라 재난을 분류하고 근력지원장치가 적용가능한 대표적 공통 재난현장을 분석하였다. 그 결과, 적용가능한 재난현장으로 13개 재난현장으로 분류되었다. 첫 번째로 사회재난현장으로 8개 현장으로 분류되었으며 각 현장은 화재현장(진압), 화재현장(구조), 붕괴사고현장, 교통사고현장, 폭발사고현장, 화생방사고현장, 환경오염사고현장, 기타 안전사고발생 현장이다. 두 번째로 자연재난현장으로 4개 현장으로 분류되었으며 각 현장은 지진발생현장, 홍수발생현장, 태풍발생현장, 기타자연재난현장이다. 마지막으로 기타 재난현장으로 1개 현장으로 분류되었다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.45-52
• /
• 2008

In order to investigate the initiation and propagation processes of a spherical detonation wave induced by direct initiation, numerical simulations were carried out using two-dimensional compressible Euler equations with an axisymmetric assumption and a one-step reaction model based on Arrhenius kinetics with various levels of ignition energy. By varying the amount of ignition energy, three typical initiation behaviors, which were subcritical, supercritical and critical regimes, were observed. Then, the ignition energy of more than $137.5{\times}10^6$ in non-dimensional value was required for initiating a spherical detonation wave, and the minimum ignition energy(i.e., critical energy) was less than that of the one-dimensional simulation reported by a previous numerical work. When the ignition energy was less than the critical energy, the blast wave generated from an ignition source continued to attenuate due to the separation of the blast wave and a reaction front. Therefore, detonation was not initiated in the subcrtical regime. When the ignition energy was more than the minimum initiation energy, the blast wave developed into a multiheaded detonation wave propagating spherically at CJ velocity, and then a cellular pattern radiated regularly out from the ignition center in the supercritical regime. The influence on ignition energy was observed in the cell width near the ignition center, but the cell width on the fully developed detonation remained constant during the expanding of detonation wave due to the consecutive formation of new triple points, regardless of ignition energy. When the ignition energy was equal to the critical energy, the decoupling of the blast wave and a reaction front appeared, as occurred in the subcrtical regime. After that, the detonation bubble induced by the local explosion behind the blast wave expanded and developed into the multiheaded detonation wave in the critical regime. Although few triple points were observed in the vicinity of the ignition core, the regularly located cellular pattern was generated after the onset of the multiheaded detonation. Then, the average cell width on the fully developed detonation was almost to that in the supercritical regime. These numerical results qualitatively agreed with previous experimental works regarding the initiation and propagation processes.