• 한국연소학회지
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• 제22권4호
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• pp.35-42
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• 2017

This case covers the issues related to the operation problem, cause analysis and improvement cases of the FGD that employed the non-leakage type GGH in coal-fired power plant for the first time in Korea. In the Cooler, there was a main problem that the tube is damaged by the ash cutting due to the high velocity of flue gas in the duct and by the weak wear resistance of material. In the Reheater, there was a main problem that the tube was corroded due to chlorine and sulfur in the circumstance of the low temperature. In order to solve those problems, we have improved the Reheater tube and tube fins by coating enamel to reduce corrosion rate.

• Tribology and Lubricants
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• 제12권2호
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• pp.20-31
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• 1996

Pressures in compression pockets consists of two identical spiral scrolls are influenced by gas flow resistance in discharge process and leakages in radial and tangential directions between two scroll wraps. In this paper, considering geometrical characteristics of these members, flow resistance and refrigerant gas leakage losses, pressure variations in compression pockets are calculated. For a scroll compressor model with fixed crank mechanism, acting load on crankshaft is analyzed. And, for a vertical type crankshaft-journal bearing system used in scroll compressor, nonlinear transient response is calculated including nonlinear fluid film reaction forces of journal bearings.

• 한국가스학회지
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• 제8권4호
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• pp.1-7
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• 2004

본 연구에서는 멤브레인식 LNG 저장탱크의 누설 안전성을 목재와 PUF로 구성된 단열재 및 예응력 콘크리트(PC) 재질이 균일하다는 가정하에 열저항 평형온도 효과를 고려하여 유한요소법(FEM)으로 해석하였다. FEM 계산결과에 따르면, 목재와 PUF로 구성된 단열재 구조물은 누설 LNG에 의해 구조물 자체가 먼저 파손되므로 누설 안전성을 보장할 수 없다. 그러나, 내부탱크와 단열재가 동시에 파손되어도 외부탱크 PC 구조물은 강도 안전성을 확보하고 있으므로 누설 LNG를 최소 10일 정도는 안전하게 지연시킬 수 있어 멤브레인식 LNG 저장탱크 시스템의 누설 안전성은 확보될 수 있다.

• 한국가스학회지
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• 제12권4호
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• pp.14-20
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• 2008

본 논문에서는 멤브레인 내부탱크, 합판, PUF 보냉재, 또 다른 합판, 예응력 콘크리트(PC) 구조물로 건설된 LNG 저장탱크의 강도안전성을 4가지의 누설해석 파괴모델에 대해 수치적으로 해석하였다. $200,000\;m^3$의 저장용량을 갖는 탱크벽면을 통한 LNG의 누설기준은 열저항 온도해석의 핵심이론이다. 결국 누설 LNG의 초저온 온도가 외부탱크의 외측벽면에서 검출되면, 이것은 저장탱크의 벽면두께를 통해 누설되었다고 가정할 수 있다. 열저항법에 기초한 누설안전성 해석결과에 의하면 합판이나 PUF 등은 벽면을 통해 누설하는 LNG를 차단할 수 있지만, 이들 벽면은 누설 LNG의 압력에 의해 파괴되므로 누설안전성을 보장하지 못한다. 그러나, PC 외부탱크는 누설된 LNG 압력을 접해도 초기에는 견디지만, 시간이 경과하면서 누설된 LNG가 탱크벽체 내부로 계속 스며들어 벽체의 온도가 급격하게 떨어지면서 누설은 진행될 것으로 예상된다. 따라서 PC 외부탱크는 누설 LNG를 일정기간 체류시켜 LNG의 누설기간을 연장하는 효과를 제공할 뿐이다.

• 한국가스학회지
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• 제9권1호
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• pp.1-8
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• 2005

본 연구에서는 $9\%$ 니켈강재식 LNG저장탱크에 대한 누설 안전성을 여러 가지 단열재와 코너 프로텍션, PC 구조물 사이에 존재하는 열저항 평형온도 효과를 고려하여 유한요소법으로 해석하였다. FEM 계산결과에 따르면, 파이버 글라스 블랑켓, 펄라이트 파우더, 셀루러 글라스 단열재 등은 재질의 취약한 강도 때문에 누설 LNG에 의한 하중이 가해지면 단열재 자체가 파손되므로 누설 안전성을 보장할 수 없게 된다. 그러나, 내부탱크와 단열재가 동시에 파손되어도 $9\%$ 니켈강재로 제작된 코너 프로텍션(CP) 예응력 콘크리트(PC)구조물의 외부탱크는 LNG의 복합하중에 대하여 강도 안전성을 확보하고 있으므로, 누설 LNG를 최소한 10일 정도는 안전하게 체류시킬 수 있다. 따라서, $9\%$ 니켈강제식 LNG 저장탱크 시스템은 이들 두 가지 구조물에 의해 누설 안전성이 확보된다.

• 한국구조물진단유지관리공학회 논문집
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• 제21권2호
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• pp.87-94
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• 2017

원자력발전소에서 철판이나 폴리머 라이너 판은 가스나 액체가 격남건물 외부로 누설되지 않도록 하기 위하여 채택되었다. 만일 어떤 사고가 발생하여 이 판이 손상을 입는 다면 콘크리트는 안전성 요구 측면에서 최후의 보루가 되어야 한다. 그 능력을 구명하기 위하여 본 논문에서는 시공이음의 유 무와 습윤조건 및 하중상태가 콘크리트의 누설저항성에 미치는 영향을 검토하기 위한 연구가 수행되었다. 실험결과로부터, 습윤상태에 시공이음이 있는 경우, 가스의 누설은 압력이 $1kg/cm^2$부터 시작되었으나 시공이음이 없는 경우는 $2kg/cm^2$부터 누설이 시작됨을 알 수 있었다. 또한, 기건 및 무재하 상태에는 시공이음의 유 무에 관계없이 콘크리트에 존재하는 가스의 통로가 일정하므로 누설량이 일정한 경향을 가지고 증가하였다. 최종적으로 재하상태에는 Okamoto et al.(1995)의 연구에서설명하는 바와 같이 누설량이 벽체의 두께에 반비례하므로 실제 발전소에 설치되는 벽체 두께를 고려하면 시공이음에 있어도 가스의 밀봉에는 문제가 없을 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.379-381
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• 2003

The sharing of common corridors by electric power transmission lines and pipelines is becoming more common place. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the near facilities. This causes induced voltages on underground metallic pipelines due to the power line currents. This could cause AC corrosion in the pipeline, which could in turn lead to disastrous accidents, such as gas explosion or oil leakage. This paper investigates for the limitation of induced voltage on the buried metal structures which is used in the inside and outside of the country. And then we measure the earth resistance and leakage current of 22.9kV distribution lines and pipe to soil potential of near pipelines in Seoul Korea. Hereby we can see the leakage current flowing through the earthing electrode have an effect on near pipelines.

• 한국자동차공학회논문집
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• 제21권1호
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• pp.23-29
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• 2013

In recent years, development of energy conversion systems using hydrogen as an energy source has been accelerated globally. Even though hydrogen is an environment-friendly energy source, safety and effectiveness issues in storage, transportation, and usage of hydrogen should be clearly resolved in every application. Therefore, sensors for detecting hydrogen leakage, especially for fuel cell electric vehicles, should be designed to have much higher resolution and accuracy in comparison with conventional gas sensors. In this study, we conducted to determine the design parameters for the semiconductor hydrogen sensor with optimized sensing conditions under the thermal distribution characteristic and thermal transfer characteristic. The heat generation study on power supply voltage was studied for correlation analysis of thermal energy according to the power supply voltage variation from 1.0 voltage to 10.0 voltage every 0.5 voltage. And we studied for the temperature coefficient of resistance with hydrogen sensor.

• KSTLE International Journal
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• 제8권1호
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• pp.11-15
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• 2007

The mechanical face seal has been tested in Korea Aerospace Research Institute (KARl) for turbopump applications. In the turbopump under current development, the mechanical face seal is installed between fuel pump and turbine to prevent a mixture of fuel and combustion gas. Generally the mechanical face seal in turbopump is exposed to severe environment because of great rotational speed, high temperature of combustion gas and high level of pressure difference. Thus a series of tests were performed to guarantee the reliability of mechanical face seal by means of simulating the practical operating conditions. The tests were conducted up to 20,000 rpm with pressure difference of 800 kPa and temperature of 620 K In addition several carbon materials for mechanical face seal were conducted to the tests to compare the life time. During the tests, the performance against leakage was monitored and the carbon wear was also measured to estimate the life of a mechanical face seal The results show that the leakage flow rates of mechanical face seal is ignorable compared to an overall flow rate of fuel pump. The carbon material which has the finest wear resistance was found during the tests. Lastly no critical failure of mechanical face seal was found during the tests and the reliability of mechanical face seal for turbopump was successfully proved.

• 센서학회지
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• 제23권4호
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• pp.266-271
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• 2014

Chemical sensors are used in various industrial facilities such high-risk and prevent the leakage of substances, important in life and environmental protection and the safe use of industry, used for management. In particular, high-temperature environments such as power generation equipment of the rotating part due to leakage generated by the various oil, power plants Shut Down, fire, work environment (exposure to various chemical solution and gas leak) and various water, air and soil pollution causes. Thus, over the long term through various channels such as crops and groundwater contamination caused by the slow, serious adverse effect on the ecosystem. In this paper, synthetic lube oil and high pressure hydraulic fluid leakage and immediately detect a new Printed Electronic implementation of technology-based film-type sensors, and its performance test. Thus, industrial accidents and environmental pollution and for early detection of problems, large accidents can be prevented. Experimental results of the synthetic lube oil and high pressure hydraulic fluid solution after the contact time depending on the experiment and the oil solution of the sensor material of the conductive porous PE resistance value by a chemical reaction could be confirmed that rapid increase. Also implemented in the film-type oil sensor electrical resistance change over time of the reaction rate and the synthetic lube oil is about 2 minutes or less, the high pressure hydraulic fluid is less than about 1 minute was. Therefore, more high-pressure hydraulic fluid such as a low volatility synthetic lube oils are the resistance change and the reaction rate was confirmed to be the slowest.