• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.119-127
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• 2011

Overhaul and repair service means the sequential processes of disassembly, repair and reassembly for a product which has been used for a long time. Overhaul is required for the companies producing airplanes, ships, trains, military weapons and heavy industrial equipments which are very expensive and have a long life cycle. The most important performance measure of the overhaul repair shop is usually the lead time. Thus, how to design the manufacturing system to meet the delivery date is a major concern in overhaul repair shop. This paper introduces the case study of an overhaul repair shop producing military weapon systems with the 3D simulation tool, $QUEST^{TM}$. At first, the characteristics of overhaul shop and what should be considered for simulation modeling are explained. Then, various simulation scenarios including two types of disassembly systems, one is flow line system and the other is cell system, are discussed with the results of simulation experiments.

• Explosives and Blasting
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• v.29 no.2
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• pp.1-12
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• 2011

Progressive collapse analyses of high-rise buildings subjected to abnormal loading such as fires, impacts, earthquakes, typhoon, bomb blasts etc. are intended. However it is difficult to perform collapse experiments of the real scale building to determine the capacity of the structure under an extreme loading events. In this study, collapse behavior of a 15 story RC structure building loaded by external explosion pressures were simulated using Extreme Loading Structures (ELS) software. The standoff distance between the RC building and explosives of 1500 kg was 1, 2, 5, 10, and 15 meters. The explosive demolition analysis techniques based on removal of partial support structures following blast scenario was adapted to investigate the transition process of progressive collapse-local damage.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.71-72
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• 2023

Asbestos is a durable and heat-resistant building material used in various building materials such as slate, ceiling tex, and spray paint. It has been banned since 2009 after found to be a first-class carcinogen that causes various cancers and asbestos lung disease. Since workers are likely to be exposed to asbestos in the process of dismantling and removal of asbestos-made building materials and facilities, laws and work standards are proposed by the Ministry of Employment and Labor to ensure the safety of asbestos dismantling work. In addition, prior studies on exposure levels and analysis methods have been conducted in this regard mainly for residents. However, the relation between the results of the risk assessment of the process conducted during the asbestos investigation and the work is still ambiguous for the safety of workers. Therefore, this study proposes a process model development methodology that considers work risk based on the results of a survey from asbestos dismantling companies.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.49-50
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• 2023

Asbestos is a building material that has been actively used because of its excellent durability and heat resistance until 2009, when it was found to be a first-class carcinogen and prohibited in Korea. Currently, asbestos dismantling is an essential process in demolition of old buildings. Workers are likely to be exposed to asbestos in the process of dismantling and removing them, which causes various occupational diseases, suggesting related laws and work standards to ensure the safety of asbestos dismantling process. Accordingly, prior studies have been conducted to analyze the level of asbestos exposure and influencing factors occurring during work, but most of them are mainly concerning health issue while research on process risks considering field characteristics and safety aspects of the work processes is still insufficient. Therefore, this study aims to derive the process risks affecting the safety of workers based on the survey results of asbestos dismantling companies, and further proposed a cost calculation model taking those risks into account.

• Journal of Korea Port Economic Association
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• v.31 no.3
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• pp.1-14
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• 2015

This study utilizes Monte Carlo simulation to forecast the time charter rate of vessels, the three-month Libor interest rate, and the ship demolition price, to mitigate future uncertainties involving these factors. The simulation was performed 10,000 times to obtain an exact result. For the empirical analysis - based on considerations in ordering ships in 2010-a comparison between the Monte Carlo simulation-based stochastic discounted cash flow (DCF) method and traditional DCF methods was made. The analysis revealed that the net present value obtained through Monte Carlo simulation was lower than that obtained via regular DCF methods, alerting the owners to risks and preventing them from placing injudicious orders for ships. This research has implications in reducing the uncertainties that future shipping markets face, through the use of a stochastic DCF approach with relevant variables and probability methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1671-1680
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• 2014

There are always much concern about the leakage of radiation materials in the event of dismantle or unexpected accident of nuclear power plant. In order to remove the leakage of radiation materials, appropriate dispersion detection techniques for radiation materials are necessary. However, because direct handling of radiation materials is highly restricted and risky, developing radiation-related techniques needs computer simulation in advance to evaluate the feasibility. In this paper, we propose a radiation imaging technique which can acquire 3D dispersion information of radiation materials and tested by simulation. Using two virtual 1D radiation sensors, we obtain stereo radiation images and acquire the 3D depth to virtual radiation materials using stereo disparity. For point and plane type virtual radiation materials, the possibility of the acquisition of stereo radiation image and 3D information are simulated.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.813-823
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• 2020

Purpose: In order to maximize the stability and productivity of the work through simulation prior to high-risk facilities and high-cost work such as dismantling the facilities inside the reactor, we intend to use digital twin technology that can be closely controlled by simulating the specifications of the actual control equipment. Motion control errors, which can be caused by the time gap between precision control equipment and simulation in applying digital twin technology, can cause hazards such as collisions between hazardous facilities and control equipment. In order to eliminate and control these situations, prior research is needed. Method: Unity 3D is currently the most popular engine used to develop simulations. However, there are control errors that can be caused by time correction within Unity 3D engines. The error is expected in many environments and may vary depending on the development environment, such as system specifications. To demonstrate this, we develop crash simulations using Unity 3D engines, which conduct collision experiments under various conditions, organize and analyze the resulting results, and derive tolerances for precision control equipment based on them. Result: In experiments with collision experiment simulation, the time correction in 1/1000 seconds of an engine internal function call results in a unit-hour distance error in the movement control of the collision objects and the distance error is proportional to the velocity of the collision. Conclusion: Remote decomposition simulators using digital twin technology are considered to require limitations of the speed of movement according to the required precision of the precision control devices in the hardware and software environment and manual control. In addition, the size of modeling data such as system development environment, hardware specifications and simulations imitated control equipment and facilities must also be taken into account, available and acceptable errors of operational control equipment and the speed required of work.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.9-16
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• 2015

This research focuses on analysis of the flight trajectory characteristics of SLBM (Submarine Launched Ballistic Missile) of North Korea. Recently, North Korea tested launching of SLBM which is threatening international security. Also it is known that North Korea had possessed the technologies about SLBM since they disassembled submarines out of commission of the former Soviet Union. If the development of the SLBM of North Korea is completed, it should be affected as asymmetric threat to South Korea. Therefore, for active respondence to these threat, it is essential to analyze the SLBM systematically. In this point of view, this work made a SLBM flight model and simulated. In addition, we controled flight trajectories according to adjusting loft angle and described their characteristics. The sea-based ballistic missile defense system is required for an effective response to the flight trajectory of the SLBM from mid-course to terminal phase.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.327-332
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• 2010

It is necessary that End-of-life Vehicle (ELV) should be recycled from the point of view of environmental preservation and resource recycling. This paper deals with two issues. The first one is the basic functional construction and plant layout of the ELV dismantling system that can maximize the reusability of parts and the recyclability of materials. The second issue is the development of a simulation model which can be used to estimate the performance of the layout design. The simulator has been interfaced with an interactive layout design system, and used to effectively determine an optimal layout design of the ELV dismantling system.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.608-613
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• 1996

본 논문에서는 고온, 고압, 그리고 방사능 준위가 높은 원자력발전소 구조물의 극한환경(Hazardous Environments)에서의 점검 및 보수에 대한 작업자의 훈련을 위해 지능형 상호협조 훈련시스템 (COINS-I: COoperative INtelligent training System-I)의 개념모델을 제안하였다. 비교적 방사능준위가 높은 격납용시 구조물과 보조(Auxiliary) 빌딩을 일차적 극한작업환경으로 설정하였다. 격납용기 구조물과 보조빌딩에 대한 가상발전소 환경(Virtual Plant Environments)을 모델링하여, 극한환경에서의 점검 및 보수훈련 Pilot 연구를 COINS-I의 개발목적으로 하였다. COINS-I은 점검, 보수훈련을 위한 가상발전소 환경을 갖는 극한작업 시뮬레이터, 지능형 Tutoring 기능을 갖는 극한작업 훈련프로그램, 3차원 가상인터페이스 등의 훈련장비를 갖는 훈련설비로 구성된다. COINS-I을 통한 교육 및 훈련 궁극적으로 작업자가 경험치 못한 극한작업(예를들면, 원자로해체, 중대사고, Life-extension 등)의 가상 시뮬레이션을 통한 훈련이 가능하여 방사능 피폭량을 저감하며, 극한작업 자동화를 위한 연구에의 활용이라 하겠다.