• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.442-445
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• 2004

The mock-up test was carried out to solve several problems of the hot weathered high strength concrete. The workability of concrete could be guaranteed by using high range water reducer containing polycarboxylic acid. The compressive strength calculation by rebound value of Schumidt hammer underestimated the actual strength of concrete structure. The temperature of concrete should be lowered by control of raw material temperature and transportation.

• Tribology and Lubricants
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• 제20권1호
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• pp.27-32
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• 2004

This paper presents unsteady oil flow behaviors in the engine lubrication network to clarify the differences between continuous and discontinuous oil supply crankshaft system. Using commercial network analysis program, Flowmaster2, engine lubrication network system analysis were carried out. And effects of crankshaft speed and supplied oil pressure on pressure fluctuation in oil groove and oil flow rate to each bearing were analyzed.

• 한국재난정보학회:학술대회논문집
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• 한국재난정보학회 2016년 정기학술대회
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• pp.181-182
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• 2016

방조제 차수공사를 실시하는 현장 지반의 하부에 철재이물질과 돌망태 와이어 등이 매립되어 있는 것으로 확인된 상황에서 강널말뚝(sheet pile)을 풍화대까지 항타하는 것이 현실적으로 불가능하므로 상부는 철재이물질(돌망태 등)이 없는 심도까지 T-4 및 Vibro Hammer 에 의한 강널말뚝(sheet pile)을 이용하여 차수하고, 철재이물질과 돌망태 와이어 등이 매립되어 있는 것으로 확인된 하부 풍화대까지는 그라우팅에 의한 차수를 시도하는 현장차수방법을 시공하여 성공적으로 차수결과를 얻을 수 있었다.

• Tribology and Lubricants
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• 제20권3호
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• pp.119-124
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• 2004

Engine bearing system is generally affected by aeration. In this paper, the aeration effects on the engine crankshaft bearing system were studied. To do this, unsteady oil flow analysis on the engine crankshaft oil circuit system was carried out. And aeration effects on the bearing system were simulated to figure out lubrication characteristics of the each bearing such as oil flow rate, minimum oil film thickness, friction loss and increase of oil temperature.

• 상하수도학회지
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• 제32권2호
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• pp.107-113
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• 2018

Maintaining adequate residual chlorine concentration is an important criteria to provide secure drinking water. The chlorine decay can be influenced by unstable flow due to the transient event caused by operation of hydraulic devices in the pipeline system. In order to understand the relationship between the transient event and the chlorine decay, the probability density function based on the water demand curve of a hypothetical water distribution system was used. The irregular transient events and the same number of events with regular interval were assumed and the fate of chlorine decay was compared. The chlorine decay was modeled using a generic chlorine decay model with optimized parameters to minimize the root mean square error between the experimental chlorine concentration and the simulated chlorine concentration using genetic algorithm. As a result, the chlorine decay can be determined through the number of transients regardless of the occurrence intervals.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.674-678
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• 2007

기술수준의 발달로 인해 건물이 대형화 고층화됨에 따라 높은 양정의 펌프를 사용하고 있으며, 배관계통을 대부분 전자식 밸브를 채택하여 입상급수라인의 수충격 현상이 대두되어 수충격 현상제어를 위한 여러 방법들이 시행되고 있다. 본 연구는 수충격 현상을 제어하는 방법 중 수충격 방지기를 이용하여 입상급수라인의 수충격 현상의 제어를 효과적으로 제어할 수 있었다. 향후 본 연구를 계속 진행 시켜나감에 따라 수충격 현상의 제어에 큰 성과를 거둘수 있을 것으로 판단된다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.45-46
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• 2006

Usual LEO satellite for earth observation use a blowdown hydrazine monopropellant propulsion system for attitude hold and orbit maintenance. For precision control, thruster valve has very short closing time, but this can cause water hammering and pressure surge. Since water hammering and pressure surge can cause damage of propulsion system and ununiform thrust, Thruster valve closing is one of the special concern during satellite propulsion system design. In this paper, an analysis for propellant feed system is conducted using the method of characteristics. The results represent water hammer effect is negligible even at the worst case and pressure surge can be decreased effectively with a trim orifice.

• 물과 미래
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• 제12권2호
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• pp.49-55
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• 1979

본 연구는 관수로내의 부정류 즉 펌푸모터의 시동, 정지 및 발브 조절시에 압력관수로에 나타나는 급변류의 현상, 특히 수격작용의 해석을 Computer에 의해 자동해석하는 방법을 강구하였다. 따라서 사용되는 관수로가 펌푸, 관망, 터널, 조압수조, 분기관, 저수지, 폐단관 및 발브장치를 갖는 일련의 관수로내에 일어나서 전자계산기를 사용하면 송수 또는 배수관로 설계에 있어 설계자의 시간과 노력을 감소하고 정확한 결과를 얻을 수 있는 장점이 있다.

• Nuclear Engineering and Technology
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• 제33권4호
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• pp.423-440
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• 2001

For sodium cooling liquid metal reactors during the last 25 years, it was most important to verify the safety of the steam generator, which absolutely requires a water leak detection system with fine sensitivity and response. This study describes the structure and leak classification of the HAMMER (Korea Advanced Liquid Metal Reactor) steam generator, compared with other classifications, and explains the effects of leak development. The requirements and experimental situations for the development of the KALIMER acoustic leak detection system (KADS) which detects micro leaks, not intermediate leaks, are introduced. We proposed four frequency bands, 1∼8kHz, 8∼20kHz, 20∼40kHz and 40∼200kHz, split effectively for analyzing the detected acoustic leak signals obtained from the sodium-water reaction model or water model in the mock-up system.

• 물과 미래
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• 제22권4호
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• pp.435-440
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• 1989

단면이 급축소되는 관에서 액체의 급속한 채움에 의한 수격현상을 연속, 운동량, 그리고 에너지 방정식들을 이용하여 해석적으로 표시하였다. 이러한 관에 기존 수학모형인 MOC와 RCT를 적용한 결과에 의하면, 이러한 관단면의 급변화에 의하여 수격작용이 예상되는 경우의 부정류해석에는 Rigid Column Method의 사용은 제한되어야 하며 Method of Characteristic를 사용하여야 한다.