• Bulletin of the Korean Chemical Society
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• 제27권8호
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• pp.1186-1188
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• 2006

In this paper a new theory is presented to treat the problem of stimulated absorption and emission of photons between energy levels from the standpoint of discrete quantum jumps. In order to implement the theory a scheme to avoid the quantum Zeno effect is proposed. Numerical simulations are performed to demonstrate that this approach does not contradict the principles of the standard wave mechanics. It is shown that with this approach one can obtain photon observation statistics as well.

• 한국철도학회논문집
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• 제4권3호
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• pp.110-115
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• 2001

Recently, many engineers actively participate in research and development w.r.t the weight reduction and the safety increase of vehicle body structure to meet the requirement of fuel economy and regulations. However, vehicle design concept related with weight reduction and safety increase is reduced to the design conflict problem. In the paper, the axial and bending collapse test of aluminum extruded beams are performed and the collapse characteristics are investigated. The analysis method to verify the fracture characteristics of aluminum extruded beam is presented and discussed.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.173-177
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• 2006

From the viewpoint of coastal hydrodynamics, one of the most important effects of global warming is a sea-level rise in coastal areas. In the present study, impacts on port facilities against sea-level rise were investigated. The sea-level rise causes the increase of the water depth, and it generates variations on the wave height, buoyancy, tidal system and nearshore current system and so on. The increase of water depth gives rise to the decrease of crown height of the structure and it causes increase of wave overtopping quantity. It may flood the port zone and its facilities, and may decrease harbor tranquility. It also leads to difficulties on navigation, mooring and loading/unloading at the port. Increase in water depth also causes increase of wave height in surf zone. This high wave makes structures unstable and may cause them to collapse during storm. In addition, increase in buoyant force due to sea-level rise also makes the gravity type structures unstable. Consequently, theses variations due to sea-level rise will cause functional deterioration of port facilities. In order to protect port facilities from the functional deterioration, reinforcement plan is required such as raising the crown height and increase in block weight and so on. Hence proper estimation method for the protection cost is necessary in order to protect port facilities efficiently. Moreover response strategies and integrated coastal zone management plan is required to maintain the function of port facilities. A simple estimation of cost for breakwaters in Korea was performed in the present study.

• 터널과지하공간
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• 제31권1호
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• pp.52-65
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• 2021

본 연구에서는 멕시코시티 외곽에 있는 프로판 저장기지인 PEMIX 터미널에서 발생한 프로판 누출에 따른 증기운 폭발을 분석하였다. 누출된 4750 kg의 프로판에 대한 TNT 등가량은 9398 kg으로 평가되었다. 폭원으로부터 40~400 (m) 떨어진 지점에서의 최대과압, 양의 압력 지속시간, 충격량과 같은 폭발변수를 TNT 등가법과 다중에너지법을 적용하여 구하였다. 폭발 변수들을 이용하여 구한 프로빗 함수를 적용하여 폐 손상, 고막 파열, 머리 충격, 전신 전위 충격으로 인한 손상 확률을 평가하였다. 고려한 모든 거리에서 다중에너지법을 이용하여 구한 최대과압이 TNT 등가법을 적용하여 구한 최대과압보다 큰 것으로 나타났으나, 200 m 이후 지점부터는 큰 차이가 없는 것으로 평가되었다. 다중에너지법에 의해 구해진 최대과압을 적용하여 구조물 손상 범위를 평가한 결과 폭원으로부터 100 m 이내에 있는 구조물의 경우 완전히 붕괴될 것으로 예측되고, 400 m 떨어진 구조물의 유리창도 거의 파손될 것으로 추정되었다. 폐 손상에 의한 사망 확률은 충격파 진행방향으로 위치하고 있는 인체의 자세에 따라 달라지는 것으로 나타났으며, 인체 주변에 반사면이 있는 경우 사망 확률이 가장 큰 것으로 평가되었다. 충격파가 폐 손상, 고막 파열, 머리 충격, 전신 전위 충격에 미치는 영향을 평가한 결과 전신 전위 충격 < 폐 손상 < 고막파열 < 머리 충격 순으로 영향을 미치는 것으로 나타났다.

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.269-277
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• 2009

The current paper focuses on the analysis of transient cavitating flow in pressurised polyethylene pipes, which are characterized by viscoelastic rheological behaviour. A hydraulic transient solver that describes fluid transients in plastic pipes has been developed. This solver incorporates the description of dynamic effects related to the energy dissipation (unsteady friction), the rheological mechanical behaviour of the viscoelastic pipe and the cavitating pipe flow. The Discrete Vapour Cavity Model (DVCM) and the Discrete Gas Cavity Model (DGCM) have been used to describe transient cavitating flow. Such models assume that discrete air cavities are formed in fixed sections of the pipeline and consider a constant wave speed in pipe reaches between these cavities. The cavity dimension (and pressure) is allowed to grow and collapse according to the mass conservation principle. An extensive experimental programme has been carried out in an experimental set-up composed of high-density polyethylene (HDPE) pipes, assembled at Instituto Superior T$\acute{e}$cnico of Lisbon, Portugal. The experimental facility is composed of a single pipeline with a total length of 203 m and inner diameter of 44 mm. The creep function of HDPE pipes was determined by using an inverse model based on transient pressure data collected during experimental runs without cavitating flow. Transient tests were carried out by the fast closure of the ball valves located at downstream end of the pipeline for the non-cavitating flow and at upstream for the cavitating flow. Once the rheological behaviour of HDPE pipes were known, computational simulations have been run in order to describe the hydraulic behaviour of the system for the cavitating pipe flow. The calibrated transient solver is capable of accurately describing the attenuation, dispersion and shape of observed transient pressures. The effects related to the viscoelasticity of HDPE pipes and to the occurrence of vapour pressures during the transient event are discussed.