• 산업기술연구
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• 제26권B호
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• pp.11-20
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• 2006

LNG is a valuable fuel since it offers some environmental, energy security and economic benefits over diesel. It could be used mainly in heavy-duty trucks and buses. Car acceleration induces the slope angle of the liquid fuel in the tank. Slope angle changes the surface area wetted by liquid fuel and consequently heat leak to the tank. This research is a result of numerical simulation of the heat leak with the car acceleration to LNG tank. The "Pro-HeatLeak" Fortran program is developed and the verification test of the developed program is done. The difference between numerical results and calculated results from MathCad verification test is less than 0.07 percent. The smallest heat leak is correspond to the case without oscillation. For the high car acceleration the value of heat leak is greater than that for the small acceleration. The difference between maximum and minimum heat leak for 10 gallons of fuel vapor in the tank is about 10 percent.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.425-430
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• 2008

To verify the system performance of portable AE leak diagnosis system which can measure with moving conditions, AE activities such as RMS voltage level, AE signal trend, leak rate degree according to AE database, FFT spectrum were measured during operation on total 11 valves of the secondary system in nuclear power plant. AE activities were recorded and analyzed from various operating conditions including different temperature, type of valve, pressure difference, valve size and fluid. The results of this field study are utilized to select the type of sensors, the frequency band for filtering and thereby to improve the signal-to-noise ratio for diagnosis for diagnosis or monitoring of valves in operation. As the final result of application study above, portable type leak diagnosis system by AE was developed. The outcome of the study can be definitely applied as a means of the diagnosis or monitoring system for energy saving and prevention of accident for power plant valve. The purpose of this study is to verify availability of the acoustic emission in-situ monitoring method to the internal leak and operating conditions of the major valves at nuclear power plants. In this study, acoustic emission tests are performed when the pressurized temperature water and steam flowed through glove valve(main steam dump valve) and check valve(main steam outlet pump check valve) on the normal size of 12 and 18 ". The valve internal leak monitoring system for practical field was designed. The acoustic emission method was applied to the valves at the site, and the background noise was measured for the abnormal plant condition. To improve the reliability, a judgment of leak on the system was used various factors which are AE parameters, trend analysis, frequency analysis, voltage analysis and amplitude analysis of acoustic signal emitted from the valve operating condition internal leak.

• 정보보호학회논문지
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• 제30권5호
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• pp.957-966
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• 2020

최근 산업기밀보호센터의 통계에 의하면 국내 기밀유출 사고의 경우 전·현직 직원에 의해 기업기밀유출의 약 80%를 차지하고 이러한 내부자에 의한 정보유출 사고의 대다수가 허술한 보안 관리체계와 정보유출 탐지기술의 이유로 발생하고 있다. 내부자의 기밀유출을 차단하는 업무는 기업보안 부문에서 매우 중요한 문제이지만 기존의 많은 연구들은 내부자에 의한 유출위협보다는 외부 위협에 의한 침입에 대응하는데 초점이 맞추어져 있다. 따라서 본 논문에서는 기업 내에서 발생하는 다양한 비정상 행위를 효과적이고 효율적으로 탐지하기 위해 내부정보 유출 시나리오를 설계하고 시나리오에서 도출 된 유출 징후의 핵심 위험지표를 데이터 분석(Data analytics)함 으로써 정교하지만 신속하게 유출행위를 탐지하는 모형을 제시하고자 한다.

• 한국재난정보학회 논문집
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• 제20권1호
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• pp.213-221
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• 2024

연구목적: 유해화학물질인 염산수용액 운송 탱크로리 누출사고 발생 시 신속하게 누출을 차단하고, 효과적으로 방재작업을 진행하여 누출로 인한 피해를 최소화하는 최적의 방안을 찾고자 하는 데 있다. 연구방법: 염산에 대한 전반적인 특성과 운송 도중 발생했었던 사고사례를 사고 유형별, 원인별로 정리하고, 염산 탱크로리의 누출 상황을 가정하여 실험할 수 있는 소형 탱크를 만들어 누출 상황과 비슷한 환경을 구성하여 여러 가지 방법으로 누출 차단 방법을 실험하여 정리하고자 한다. 연구결과: 실험을 통하여 효과적인 누출 차단 방법을 확인하였다. 누출사고 발생 시 신속하게 차단하는 방안을 정리하여, 사고현장에서 적용할 수 있는 최적의 방재방안을 제시하고자 한다. 결론: 누출 차단은 접착테이프와 자석을 조합하여 사용하는 편이 차단에 효과적인 것으로 확인됐다. 사업장 비상 출동팀 및 제품 운송기사들에게 누출 차단 장비를 적절하게 선택하여 대응하도록 반복 훈련하면 신속한 대응이 가능하다. 향후 다양한 누출 차단 방안에 관한 추가적인 연구의 진행이 필요하다.

• 한국초전도ㆍ저온공학회논문지
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• 제2권1호
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• pp.7-13
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• 2000

A rotating cryogenic system was designed similar to the cooling system for the rotor of a superconducting generator. The experimental rotor has an inner vessel which simulates the winding space of an actual superconducting rotor, and a torque tube of comparable design. This paper describes the evaluation of the total heat leak into the inner vessel that leads to the study of the heat transfer characteristic of the rotating cryogenic system. To examine the insulation performance of the experimental rotor. temperature was measured at each part of the system at various rotaing speeds from 0 rpm to 600 rpm. Total heat leak into the inner vessel was calculated by measuring the boil-off rate of liquid helium. Conduction heat leak to the inner vessel was obtained by the vent tube, and radiation heat leak was calculated by subtracting the conduction heat lent from the total heat leak. There seemed to be no rotaional dependency of total heat leak at least up 600 rpm.

• Journal of Advanced Marine Engineering and Technology
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• 제30권7호
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• pp.771-781
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• 2006

Car acceleration or deceleration induce the surface slope of liquid fuel in the LNG tank. Slope changes the surface area wetted by liquid fuel in the tank and consequently heat leak to the tank. The Fortran program, 'Pro-Heatleak', is developed to evaluate heat leak on LNG tank. The verification test proves the high accuracy of the developed program. The difference between MathCad and computational results is less than 0.07 %. Computational analyses of heat leak are carried out for 10 gallons and 20 gallons of fuel vapor in the tank. With the increasing of fuel vapor volume by 10 percent the wetted surface area and heat leak respectively decrease by 13 percent. The difference between maximum and minimum heat leak is about 10 percent for both 10 gallons and 20 gallons of fuel vapor in the tank.

• 산업기술연구
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• 제27권B호
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• pp.65-70
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• 2007

The LNG tank are properly designed to fit with the limited installation space of a light duty truck, Hyundai Porter II. This designed LNG tank has 36 liter capacity, so two LNG tanks installed on Porter II truck allow it to run about 432 km per fueling. It is almost two times greater than CNG mileage for same truck. To analyze the relationship between car acceleration and heat leak for different fuel vapor/liquid ratios, the modified Fortran program "Pro-Heatleak" is used. Computational analysis shows that the relationship between the heat leak and vapor/liquid ratio is linearly inversed. Heat leak increases with increasing of car acceleration when fuel vapor/liquid ratio is less than 0.5 and decreases when fuel vapor/liquid ratio is greater than 0.5. The difference between maximum and minimum heat leak for full tank is about 12 percents. For the fuel vapor/liquid ratio equal to 0.5 heat leak does not depend on car acceleration.

• 반도체디스플레이기술학회지
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• 제20권2호
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• pp.14-18
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• 2021

Electric Vehicle industry requires high technologies to stabilize apparatuses for the Coolant heater manufacturing. Vibrations of Leak Machine are one of the most critical factors for causing delivered of the defective product or poor inspection, which are the main reasons of the defects. In this study, the structure of the Leak Machine was analyzed through the experiment and the computer simulation to investigate the main reasons of the vibrations, and further to alter the design for the improved stability. And that design alterations were applied to the machine to identify the effects of those alterations. The result of the study shows that design alterations of the Leak Machine can effectively suppress about 97.8% of the vibrations, and further can improving the Inspection precision of the Coolant heater.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 춘계학술발표대회 논문집 제23권 1호
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• pp.225-230
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• 2004

Leak noise is a good source to identify the exact location of a leak point of underground water pipelines. Water leak generates broadband noise from a leak location and can be propagated to both directions of water pipes. However, the necessity of long-range detect ion of this leak location makes to identify low-frequency acoustic waves rather than high frequency ones. Acoustic wave propagation coupled with surrounding boundaries including cast iron pipes is theoretical analyzed and the wave velocity was confirmed with experiment The leak locations were identified both by the acoustic emission (AE) method and the cross-correlation method. In a short-range distance, both the AE method and cross-correlation method are effective to detect leak position. However, the detect ion for a long-range distance required a lower frequency range accelerometers only because higher frequency waves were attenuated very quickly with the increase of propagation paths. Two algorithms for the cross-correlation function were suggested and a long-range detection has been achieved at real underground water pipelines longer than 300m.

• 전자공학회논문지
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• 제53권10호
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• pp.95-102
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• 2016

육상에서 석유 제품의 수송에 가장 많이 활용되는 방법이 송유관을 이용하는 방법이다. 그러나 누유 혹은 도유로 인한 대형사고 및 환경 재해의 위험이 있기 때문에 일반적으로 누유 감지 시스템 (Leak Detection System)을 활용하여 이에 대처하고 있다. 장거리 송유관에 많이 활용되는 방법은 저압확장파((Negative Pressure Wave)를 활용한 누유 감지 기법인데 저압확장파 기반의 시스템은 감지 성능이 뛰어나지만 높은 오알람 발생률로 인하여 누유 알람의 신뢰성이 저하되는 단점이 있다. 본 논문에서는 송유관 양단의 유량 차이 (Volume Balance) 비교를 추가로 활용하여 저압확장파 기반 누유 감지 시스템의 오알람을 필터링하는 알고리즘과 실험 결과를 제시한다.