• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.32 no.10
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• pp.27-30
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• 2003

배수관내의 공기의 압력변동을 완화시키는 방법의 하나인 통기밸브 등에 대해 소개한다. 배수설비의 목적은 위생기구로부터의 오배수를 건물 밖으로 신속하게 배출함과 동시에 배수관내에 악취성분을 포함하고 있는 오염된 공기가 실내로 침입하여 실내공기가 오염되는 것을 방지하기 위한 역할도 한다. 하수가스의 침입을 방지하기 위해 각종 형상의 배수트랩을 설치하는데, 여러 가지 원인에 의해 트랩내의 봉수는 파괴되기도 한다. 봉수파괴 원인 중에서도 가장 큰 영 향을 미치는 사이 폰 작용에 의한 봉수 파괴는 배수 수직관 및 수평주관내의 공기의 압력변동이 원인(유도사이펀 현상)이 되어 발생하거나 배수자신(자기사이펀 현상)에 의해 발생한다. 배수관내의 압력은 배수부하가 발생한 경우에는 그 배수에 의한 공기의 이동 등에 의해 변동하며, 배수가 없어도 배수관 접속부의 기압변동이나 상승기류에 의해 변동된다.(중략)

• Water for future
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• v.52 no.5
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• pp.28-35
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• 2019

• Journal of the KSME
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• v.25 no.5
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• pp.406-412
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• 1985

연소 동안에 크랭크 축은 오일 필름을 통하여 연소압력이 실린더 블록으로 전달된다. 점화 전에 관성력에 의한 크랭크 축의 굽힘 변형은 크랭크 축으로부터 메인 베어링까지의 연소하중 전달에 큰 영향을 미친다. 메인 베어링에 베어링 보를 부착시키거나 크랭크 축의 굽힘 강성을 변화시켜 실린더 블록의 스커어트 진동을 감소시키는 효과를 얻었다. 크랭크 축의 비틂 진 동을 일으키는 회전력과 관성력 변동의 합력은 크랭크 저어널의 횡진동을 일으킨다. 크랭크 축의 횡 강제진동은 베어링 1에서 최대값이기 때문에 실린더 블록의 굽힘, 비듦 진동에 대하여 기진력이 된다. 실린더 블록의 진동 진폭은 관성력 변동의 주파수가 실린더 블록의 공진진 동수에 가까워지는 정도와 크랭크 축 비듦 진동의 진폭에 의존한다. 크랭크 풀리의 극관성 모우멘트와 크랭크 축 비듦 진동을 감소시키는데 효과를 준다.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.44-50
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• 2002

The connecting rod big-end bearing is one of the most heavily loaded components of the lubrication system of high-speed combustion engines. The supply oil flow has to pass to the main bearing and the rotating crankshaft before entering the connecting rod bearing. It is common knowledge that the centrifugal forces due to the crankshaft rotation influence the oil flow to connecting rod bearing through the oil supply bore, especially, when the oil supply system to the connecting rod bearing has a 180$^{\circ}$circumferential groove via a single drilling in the crankshaft. In this case, it should be confirmed that the groove oil pressure in the main bearing is sufficient to overcome these centrifugal forces. For the purpose, the dynamic oil pressure before entering oil supply bore to the connecting rod bearing was measured instead of averaged oil pressure in main gallery. Experimental test results show that the dynamic oil pressure in the oil groove was more useful than that of main gallery. And it was also found that the oil pressure fluctuation in the groove was sensitively affected by the reduction of the main bearing clearance.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.611-618
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• 2000

The test facility of the 1/60-scale models for the train-tunnel interactions was recently developed to investigate the effects of entry portal shapes, hood shapes and air-shafts for reducing the micro-pressure waves radiating to the surroundings of the tunnel exits by KRRI in Korea. The launching system of train model was chosen as air-gun type. In present test rig, after train model is launched, the blast wave by the driver did not enter to inside of the tunnel model. The train model is guided on the one-wire system from air-gun driver to the brake parts of test facility end. Some cases of the experiments were compared with numerical simulations to prove the test facility.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1066-1072
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• 2000

This study is to investigate the pressure wave characteristics and the absorption of maximum and minimum pressure generated by instantaneous valve closure at the end of the straightening copper piping system with and without a water hammer arrester. Experiments were conducted under the following conditions : initial pressure 1~5 bar, flow velocity 0.6~3.0 m/s, water temperature $20^{\circ}C$ and air volume of water hammer arrester $80~180^cm^3$. Experimental results show that the optimum air volume of water hammer arrester is 110㎤.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.63-63
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• 2018

최근 이상기후로 인한 국지성 호우의 발생빈도 및 강우강도의 증가는 하천횡단구조물의 안정성에 문제가 되고 있다. 하천 횡단구조물(보, 물받이공 등)의 파괴는 국부 세굴(bed scour), 파이핑(piping), 구조물 본체의 불안정성 등의 원인으로 발생되고 있으며, 이 중에서 구조물 본체의 불안정성은 도수(hydraulic jump)로 인한 압력변이도 주요 원인이 될 수 있다 (Bower and Toso, 1988; Kazemi, F. et al., 2016). 그러나, 현재 직접적인 파괴 원인인 세굴 등에 대한 연구에 비해 압력변이로 인한 구조물의 파괴원인을 분석하는 연구는 미비한 실정이다. 본 연구에서는 다양한 흐름조건을 발생시켜, 하천횡단구조물 주변의 도수특성 및 도수로 인한 압력변이에 대하여 수리실험 및 수치모의를 통하여 검토하고자 한다. 수리실험에 사용하는 수로는 길이 10 m, 폭 0.3 m, 높이 0.4 m이며 상류로부터 2.5 m 떨어진 곳에 보(weir)를 설치하였다. 실험조건은 다양한 흐름조건에 따른 도수 발생을 검토하고자 상하류 수위를 조절을 통해 Froude 수의 범위를 1 < Fr < 10로 설정하였다. 압력변이는 전압형 압력계(Model : UNIK 5000, 압력 측정 변위 : -2 ~ 5 kPa)를 사용하였으며, 보(weir) 하류단에서 2.5 cm 간격으로 천공하여 측정하였다. 또한 3차원 모형인 FLOW-3D 모형을 이용하여 실험수로를 재현하였으며, 도수 발생 위치, 도수 길이, 도수 발생 시 압력변이에 대하여 실험결과와 수치모의 결과를 비교하여 수치모형을 검증하였다. 최종적으로 Froude 수에 따른 도수특성(도수 발생위치, 도수 길이 등) 및 최대 압력변이를 무차원화 하여 나타내었다. 본 연구는 도수 발생 시 압력변이로 인한 구조물 파괴분석에 대한 기초가 되는 기본적인 연구이나, 향후에는 물받이공 길이, 두께 등 하천횡단 구조물 설계인자 도출에 선행연구로 발전할 수 있다고 판단된다.

• Journal of Hydrogen and New Energy
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• v.16 no.1
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• pp.66-73
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• 2005

Hydrogen linear power system is estimated as the next generation power system which can obtain a performance as same as fuel cell. In order to develop Hydrogen combustion power system with high thermal efficiency, it is very important to understand the basic characteristics of hydrogen combustion and establish combustion stabilization technique of its system. In this study, RICEM(Rapid Intake Compression Expansion Machine) for researching of hydrogen combustion linear power system was manufactured and evaluated, and the basic characteristics of linear RICEM were analyzed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.2
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• pp.90-101
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• 2009

Analysis of multi-channel seismic reflection data from the Southern Ulleung Basin reveals that Plio-Quaternary section in the area consists of nine stacked sedimentary units separated by erosional unconformities. On the southern slope, these sedimentary units are acoustically characterized by chaotic seismic facies without distinct internal reflections, interpreted as debris-flow bodies. Toward the basin floor, the sedimentary units are defined by well-stratified facies with good continuity and strong amplitude, interpreted as turbidite/hemipelagic sediments. The seismic facies distribution suggests that deposition of Plio-Quaternary section in the area was controlled mainly by tectonic movement and sea-level fluctuations. During the Pliocene, sedimentation was mainly controlled by tectonic movements related to the back-arc closure of the East Sea. The back-arc closure that began in the Miocene caused compressional deformation along the southern margin of the Ulleung Basin, resulting in regional uplift which continued until the Pliocene. Large amounts of sediments, eroded from the uplifted crustal blocks, were supplied to the basin, depositing Unit 1 which consists of debris-flow deposits. During the Quaternary, sea-level fluctuations resulted in stacked sedimentary units (2-9) consisting of debris-flow deposits, formed during sea-level fall and lowstands, and thin hemipelagic/turbidite sediments, deposited during sea-level rise and highstands.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.319-332
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• 2015

The pressure wave formed by the piston effects of the train proceeds within the tunnel when a train enters the tunnel with a high speed. Depending on the condition of tunnel exit, the compression waves reflect at a open end, change to the expansion waves, transfer to tunnel entrance back. Due to interference in the pressure waves and running train, passengers experience severe pressure fluctuations. And these pressure waves result in energy loss, noise, vibration, as well as in the passengers' ears. In this study, we performed comparison between numerical analysis and field experiments about the characteristics of the pressure waves transport in tunnel that appears when the train enter a tunnel and the variation of pressure penetrating into the train staterooms according to blockage ratio of train. In addition, a comparative study was carried out with the ThermoTun program to examine the applicability of the compressible 1-D model(based on the Method of Characteristics). Furthermore examination for the adequacy of the governing equations analysis based on compressible 1-D numerical model by Baron was examined.