• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.904-907
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• 2011

Various types of gases and propellants are used in launch vehicle. In order to fulfill the mission of the launch vehicle, the components and systems used in launch vehicle should ensure flawless operation in these environments. The pneumatic test is the test performed using compressed gas to prove requirements of the components and systems. This paper describes the requirements of the gas quality for pneumatic test, leak test method, and pneumatic test of the launch vehicle.

• 동력기계공학회지
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• 제11권3호
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• pp.35-40
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• 2007

Leak would happen because of the damage of high temperature and high-pressure valve in nuclear power plant. condition based prevention maintenance is essential by using the suitable method based on local condition. Energy loss prevention can prevent from an accurate test, Local actually and ability. The methods of test for high energy fluid leak at present are analysis of ${\Delta}T$, AE(Acoustic Emission) analysis, and thermal image. The result for test of secondary system in nuclear power plant Unit reveals that the AE occurred clearly in leakage situation, but thermal image didn't occur. It is identified that leak is occurred when the orifice located front and back of valve operates. It shows that making a impatient judgment by using the single method if it is leakage is containing uncertainty. So we think that using the Multi-Measuring method is more sound judgment than single-measuring method.

• 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.

• Corrosion Science and Technology
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• 제3권6호
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• pp.233-239
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• 2004

Primary water stress corrosion cracking of steam generator tubings occur on many tubes in pressurized water reactors(PWRs), and they are repaired using sleeves or plugs. In order to develop proper repair criteria, it is necessary to know the leak behavior of the tubes, which have stress corrosion cracks. Crack development tests were carried out on the tubes at room temperature, and leak rate and burst pressure were measured on the degraded tubes at room temperature and a high temperature. No leakage was detected on the tubes where 100 % through wall crack developed, at 1560 psi, which is an operating pressure difference of pressurized water reactors(PWRs). In some tests, leak rates of the tubes increased with time at a constant internal water pressure. A test tube showed a very small amount of leakage at 2700 psi in a high temperature pressure test at $282^{\circ}C$, but it disappeared after the pressure increased slightly. Even cracks are 100 % through wall, they need to open in order to reach a certain amount of leak rate at the operating pressure difference.

• 상하수도학회지
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• 제31권5호
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• pp.459-469
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• 2017

A real scale leakage test facility was developed to study the leak signal characteristics of water supply pipelines, and then leak tests were carried out. The facility was designed to overcome the limited experimental circumstances of domestic water supply pipeline experimental facilities. The length of the pipeline, which was installed as a straight line, is 280m. Six pipes were installed on a 70m interval with different pipe material and diameters that are DCIP(D200, D150, D100, D80), PE(D75) and PVC(D75).The intensity of the leakage is adjusted by changing the size of the leak hole and the opening rate of ball valve. Various pressure conditions were simulated using a pressure reducing valve.To minimize external noise sources which, deteriorate the quality of measured leak signal, the facility was built at a quiet area, where traffic and water consumption by customers is relatively rare. In addition, the usage of electric equipment was minimized to block out noise and the facility was operated using manual mode. From the experimental results of measured leakage signal at the facility, it was found that the signal intensity weakened and the signal of high frequency band attenuated as the distance from the water leakage point increased.

• 공업화학
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• 제9권7호
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• pp.1023-1029
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• 1998

5Cr-1Mo steel을 이용하여 나트륨 분위기에서 미량 물 누출 실험을 수행하였다. 시편에서 미량 물 누출로 인한 누출경로의 완전 re-open time은 129분으로 나타났고, 그 크기는 직경 2mm를 나타냈다. 누출경로는 re-open되기 전에 누출부위를 중심으로 halos현상을 형성하였으며, halos의 크기와 실제 re-open크기와는 다르게 나타났다. 나트륨-물 반응으로 인한 재질의 부식은 나트륨부위로부터 시작되었으며, steam 부위에서는 부식이 발생하지 않았다. 시편 누출부위를 AES로 분석한 결과 Cr의 segregation이 가장 많이 나타났으며, SEM과 EPMA 관찰로부터 나트륨화합물들이 누출부위 주변에 대량 침적되어 있는 것이 관찰되어 나트륨 철 크롬혼합물 형태로 부식생성물들이 혼재되어 있는 것으로 예측되었다.

• 한국정밀공학회지
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• 제23권11호
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• pp.50-57
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• 2006

The water leak in water-cooled generator stator windings can generate the serious accidents such as insulation breakdown and it brings a generator to the unexpected sudden outage. Accordingly, it is important to diagnose the water absorption of them for the effective operation of power plant. Especially, the capacitance value which is measured for diagnosis is very small so the special diagnosis methods like stochastic theory are needed. KEPRI developed the water absorption test equipment and diagnosis technology for them. The developed diagnosis technology is applied to the real system and the results of water absorption test for stator windings are agreed to them of water leak test.

• Journal of Electrical Engineering and Technology
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• 제7권2호
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• pp.230-235
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• 2012

Cases of insulation breakdown damage of water-cooled generator stator windings occur frequently due to coolant leakage and water absorption worldwide. Such serious accidents may cause not only enormous economic loss but also very serious grid accidents in terms of stable supply of electric power. More than 50 % of domestic generators have been operated for more than 15 years, and leak and water absorption problem of windings are often found during the planned preventive maintenance period. Since 2005, leak and water absorption tests have been performed for total watercooled stator windings after fully drying the inside of the windings. The results are then comprehensively analyzed. The result of the test performed by GE, a foreign manufacturer, for 141 generators showed failures in 80 of them (failure rate: 57 %), whereas in the tests carried out in Korean domestic power plants, only 14 out of 50 generators showed failures (failure rate: 28 %).

• 동력기계공학회지
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• 제14권5호
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• pp.71-75
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• 2010

Leak detection technology is a challenging research until nowadays, because it has wide and various applications in industry. Furthermore pneumatic component reliability test based on ISO requires air leakage measurement. The conventional measurement methods need a complex operation and the calibration of leak detector. Tracing the history of our study, we proposed a new method for measurement of leak flow rate using isothermal chamber. In this study, propose a simulation model of isothermal chamber by infinitesimal flow -rate, such as a leak flow-rate. The effectiveness of the proposed simulation model is proved by simulation and experimental results. Base on the comparison results, proposed simulation model is good agreement with experimental results.

• 공업화학
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• 제9권5호
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• pp.674-679
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• 1998

액체금속로 증기발생기 전열관 재질로 사용이 예상되는 ferrite steel 시편을 사용해서 소듐분위기에서 미량의 물 누출 실험을 수행하였다. 누출경로는 소듐-물 반응생성물 및 부식생성물에 의한 self-plugging 현상과 열적인 transient 및 전열관의 vibration에 의한 re-opening 메카니즘으로 설명이 가능하였다. 실험결과, 600 Psig의 injection 압력으로 5 g $H_2O$를 소듐분위기 속의 시편으로 누출시킨 경우, 누출초기와 약 70분 경과 후에 약간의 누출 흔적이 보였으나, self-plugging되었던 누출경로는 129분이 경과되자 완전 re-opening된 것으로 확인되었다. 누출시편의 re-opening shape은 2중으로 되어 있었으며, 소듐부위에서 시편 표면에 나타난 re-opening size 약 2 mm의 직경을 나타내었다.