• 대한방사선방어학회:학술대회논문집
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• 2009.11a
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• pp.98-99
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• 2009

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.31-39
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• 2013

Nuclear fuel can be damaged under unexpected circumstances in a nuclear reactor. Fuel rod failure can be occurred due to debris fretting or excessive hydriding or PCI (Pellet-to-clad Interaction) etc. It is important to identify the causes of such failed fuel rods for the safe operation of nuclear power plants. If a fuel rod failure occurs during the operation of a nuclear power plant, the coolant water is contaminated by leaked fission products, and in some case the power level of the plant may be lowered or the operation stopped. In addition, all spent fuels must be transferred to a dry storage. But failed fuel can not be transferred to a dry storage. Therefore, the purpose of this study is to develop a system which is capable of inspecting whether the spent fuel in the storage pool is failed or not. The sipping technology is to analyze the leakage of fission products in state of gas and liquid. The failed fuel inspection system with gamma analyzer has successfully demonstrated that the system is enough to find the failed fuel at Wolsong plant.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1273-1279
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• 2010

Pressure tubes at the CANada Deuterium Uranium (CANDU) nuclear power plants are periodically inspected in accordance with the CSA N285.4 code. If flaws that do not satisfy the criteria given in CSA N285.4 are detected, the code permits a fitness-for-service assessment to determine the acceptability of the flawed pressure tubes. In this paper, the Wolsong In-service Evaluation System (WIES) is introduced; this system has been developed for the assessment of the flawed pressure tubes and is based on CSA N285.8. Since the system evaluates the integrity of flawed pressure tubes exactly and promptly during an in-service inspection, it will help in operating the Wolsong nuclear power plants without prolonging the outage period.

• Elastomers and Composites
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• v.49 no.4
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• pp.305-312
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• 2014

Most of military supersonic aircraft use an afterburner. It plays an important role in performing unusual duties for supersonic flight, takeoff, and combat situations. Recently, repetitive fuel leakage from the inner piston packing rubber of afterburner fuel pump in an aircraft J85-GE-21 turbojet engine has happened. These failures have only happened in one manufacturer's parts of two manufacturers. Thus, the cause of these failures was investigated through the comparative analysis for both the failed and the unfailed with two different manufacturers using various analysis methods. The failure analysis was performed using analysis methods such as swelling or swelling ratio, total sulfur content, polymer identification, loading and surface area of carbon black, and hardness. Consequently, the main cause of this failure was identified to be insufficient loading of carbon black as a reinforcing agent, together with small surface area of carbon black and somewhat low sulfur content.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.558-567
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• 2020

This study examined the defect characteristics of fuel flow proportioner-mounted structures to analyze the causes of structural defects during aircraft operation. System vibrations and single component vibrations that occur during aircraft operations are usually the cause of structural defects. The fuel flow proportioner causes a defect in the support structure due to the vibration caused by the pressure change caused by the sudden increase in the flow rate. Defects in the support structure of the fuel flow proportioner are not correlated directly with the cracking of the maneuver, and flight time according to aircraft operation analysis is related to the use of A/B. The structural reinforcement configuration was confirmed through static and life analysis of the cracks of the bracket mounted under the fuel flow proportioner for improvement of the defect. An analysis of the reinforcement revealed a minimum structural strength of +0.15. Structural life analysis confirmed that the stress acted on the site under 15Ksi. The fatigue life was confirmed to be more than 7,700 Cycles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.289-292
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• 2006

In this paper, the hybrid algorithm of Support Vector Machine md Artificial Neural Network is used for the defect diagnostics algorithm for the aircraft turbo-shaft engine. The results of learning of ANN, especially, accuracy or speed of convergence are sensitive to the number of data, so a comparison between design point and off-design area, especially, Mach number and fuel flow variable area, is essential research. From application results for diagnostics of gas turbine engine, it was confirmed that the hybrid algorithm could detect well in the of-design area as well as design point.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.707-712
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• 2014

Aircraft fuel indicator is a device to indicate the amount of fuel remained during flight, where accurate and consistent operation of the indicator should be maintained. Previously the Korean Utility Helicopter fuel indicator sporadically displayed abnormal sign by "8888" during flight, jeopardizing flight safety. Inappropriate EMI/EMC performance was detected during trouble shooting process. The cause of the abnormal display was found to be resulted from unstable power induced by electro-magnetic disturbance and CAN communication error. The aircraft fuel indicator design was improved and the design compatibility was verified to avoid abnormal display.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.81.1-81.1
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• 2010

SOFC 발전시스템의 상용화를 위해 선행되어야 할 것은 스택의 안정적 출력 및 신뢰성 확보이다. 이를 이루기 위해서는 스택을 구성하는 구성요소의 신뢰성 있는 규격 및 검수가 필요하다. 즉, 셀, 밀봉재, 분리판 및 집전체로 대변되는 구성요소들이 스택에 장착되었을 때 그 기능을 최대한 발휘하면서도 점진적 또는 급격한 품질저하가 발생되지 말아야 한다. 특히, 셀의 경우 스택의 성능에 직접적인 영향을 미치는 구성요소로서 품질에 대한 명확한 검수기준이 필요하다. SOFC용 셀은 다공성 anode, 치밀한 전해질, 그리고 다공성 cathode로 구성된 세라믹 소결체이다. 이 때 치밀한 전해질에 결함이 내재되어 있거나 물리적 힘에 의해 신규로 발생할 경우, 연료로 사용되는 수소와 공기가 만나는 cross-over가 발생하게 된다. Cross-over는 연료가 소모되는 문제도 있지만 발열로 인한 Hot spot을 형성시켜서 주변과의 온도구배를 유발하고, 이로 인해 고체 전해질의 균열전파를 일으킬 수 있고 나아가 급격한 셀의 파괴를 야기할 수 있다. 본 연구에서는 SOFC에 사용되는 셀의 형상측정, 물리적 강도 및 결함 검출을 위한 검수기법을 개발하여 스택의 신뢰성 향상과 향후 규격표준화를 위한 기반을 제공하고자, 평판형 셀의 3차원 형상을 정밀하게 측정하는 장치와 일정 면압을 인가하여 특정 형상을 갖고 있는 셀의 물리적 파괴여부를 판단할 수 있는 장치, 그리고 셀의 전해질에 내재된 결함을 검출할 수 있는 장치를 제작하였다. 본 장치들은 $1,000cm^2$급 평판형 셀까지 검수할 수 있도록 고안하여 양산시스템에 접목시킬 수 있도록 고안된 것이다. 본 장치들을 이용한 검수결과, 현재 $700cm^2$급 평판형 셀의 경우 최대 camber가 4mm 이하, 전해질의 He leak rate는 $5{\times}10^{-5}mbar.l/s.cm^2$ 이하라는 검수규격을 본 연구소에서 운전하는 스택에 1차적으로 적용하였으며 현재 검수규격의 신뢰성 및 강화를 위한 연구를 수행 중에 있다.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.633-634
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• 2004

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.112-117
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• 2016

The standard(KS D 3631) should be obey for using fuel gas pipe in Korea and a carbon steel pipe is coated with synthetic resine for protecting the corrosion. The coating is just performed for anti-corrosion, and actual strength of pipe is given by the carbon steel pipe when the fuel gas is transported. When the flaws are occurred in the steel pipe, the estimation method which is used for residual strength is necessary. But the suitable method is not exist for applying the fuel gas pipe. Eventually, the residual strength is estimated by overseas regulation such as ASME B31G or DNV RP F101. But the method based on the relative regulations are not sufficiently valid and it can not estimate the 85% over even. Therefore, the test was performed for validation with pipe specimen. The specimen was made with artificial flaw. The test results showed the certain differences according to flaw depth and DNV RP F101 is suitable to estimate the residual strength in Korea. The results in this paper contain in case of the severe flaw depth and suitable mode for Korea, so the result can be expected as valuable and widely used in various field.