• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 추계학술대회 논문집
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• pp.487-488
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• 2003

우리나라 대기환경기준이 점차 강화되고 있고, 국민의 욕구수준 또한 선진국 수준으로 강화될 계획으로 있어 이에 따른 대기오염 방지시설의 설치 또는 보완이 요구되고 있다 특히, 배기가스 중 황산화물 및 질소산화물 배출농도 강화로 울산화력발전소에서는 최신의 배연탈황ㆍ탈질설비를 가동중에 있으나 황산 Mist가 주요원인으로 추정되는 Plume Opacity가 발생되어 오염물질 배출농도는 법적규제기준 이내로 배출되더라도 민원이 발생되고 있다. 이에 대한 대책으로 현장에 적합한 연료첨가제 주입으로 Plume Opacity 발생원인을 제거함과 동시에 배연탈황설비에서 발생된 저온부식 현상을 개선하고, 보일러 내 고온부식 등 연소장애 현상 개선을 통한 열효율 향상 방안에 대해 연구하였다. (중략)

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.2105-2108
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• 2003

The characteristics of upward bubble flow were experimentally investigated in a liquid bath. In the present study, a thermal-infrared camera and high speed CCO camera were used to measure their temperature and local rising velocity, respectively. Heat transfer from bubble surface to water is largely completed within z=10mm from the nozzle, and then the temperature of bubble surface reaches that of water rapidly. The rising velocity of bubble was calculated for two different experimental conditions: 1) bubble flow without kinetic energy 2) with kinetic energy. Bubble flow without kinetic energy starts to undergo the effect of inertia force 10cm away from the nozzle. Whereas, kinetic energy is dominant before 30 cm away from the nozzle in bubble flow, but after this point, kinetic energy and inertial force are applied on bubble flow at the same time.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.739-740
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• 2010

1단용 액체로켓엔진 후류 때문에 발생하는 유도로의 열적 부하를 감소시키기 위한 방법 중 물분사 방식의 효과적인 냉각 성능을 고찰하기 위해 두 가지 방법과 다양한 물분사 조건에 대해 수치적 계산을 수행하였다. 중앙분사 방식이 측면분사 방식보다 보다 효과적으로 후류를 냉각시켜 유도로의 열적부하를 감소시킴을 알 수 있었다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 춘계학술대회 논문집
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• pp.247-253
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on "how to dispose the treated municipal water and wastewater in harbor" brings peoples′ concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water and tidal changes, CORMIX(Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1572-1577
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• 2003

High-power pulsed laser ablation under atmospheric pressure is studied utilizing numerical and experimental methods with emphasis on recondensation ratio, and the dynamics of the laser induced vapor flow. In the numerical calculation, the temperature pressure, density and vaporization flux on a solid substrate are first obtained by a heat-transfer computation code based on the enthalpy method, and then the plume dynamics is calculated by using a commercial CFD package. To confirm the computation results, the probe beam deflection technique was utilized for measuring the propagation of a laser induced shock wave. Discontinuities of properties and velocity over the Knudsen layer were investigated. Related with the analysis of the jump condition, the effect of the recondesation ratio on the plume dynamics was examined by comparing the pressure, density, and mass fraction of ablated aluminum vapor. To consider the effect of mass transfer between the ablation plume and air, unlike the most previous investigations, the equation of species conservation is simultaneously solved with the Euler equations. Therefore the numerical model computes not only the propagation of the shock front but also the distribution of the aluminum vapor. To our knowledge, this is the first work that employed a commercial CFD code in the calculation of pulsed ablation phenomena.

• 한국해양학회지:바다
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• 제5권4호
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• pp.363-373
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• 2000

남서태평양 열수해역의 화학적 환경특성을 이해하기 위하여 수온, 염분, 투명도, pH, 영양염 및 황화수소 등을 분석하였다. 시료는 마누스분지의 12개 정점에서 CTD를 이용하여 채취하였다. 열수작용은 해수 및 암석간의 순환작용에 의해 이들의 물리, 화학적 특성을 변화시키고, 주변의 해수와는 특성이 다른 열수가 plume을 형성하여 해양으로 공급된다. 본 연구에서는 남서태평양 PACMANUS 해역과 Susu Knolls 해역에서 투명도 및 황화수소를 이용하여 열수작용에 의한 plume을 확인하였다 특히, 열수환경을 지시하는 지화학적 추적자인 황화수소는 0${\sim}$3.31 ${\mu}$M 범위와 평균 0.63${\mu}$M을 보였다. 열수작용에 의한 plume의 높이, 분출량 및 활동도는 저층해류 순환 등의 영향을 받으며 수층의 등밀도면을 따라 주변 해수로 확산된다. 결과적으로 연구 해역에서의 황화수소 농도 이상치는 열수작용에 의한 영향으로 판단되고, 따라서 PACMANUS 해역의 남북방향에 가장 큰 공급원이 있을 것으로 보인다.

• 한국해안해양공학회지
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• 제6권4호
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• pp.413-420
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• 1994

하천수 플룸(plume)의 퍼짐을 다루는 역학은 플룸의 경계면이 시간과 공간에 따라서 변하기 때문에 자유경계조건의 문제(free boundary problem)로 다루어야 하는 대단히 복잡한 비선형 문제이다. 더욱이 플룸경계를 통한 주변수의 혼합까지 고려할 경우 그 복잡성은 한층 더해진다. 이러한 비선형성과 복잡성을 피하는 기법의 하나가 적분해석법인 바, 본 논문에서는 하천수 플룸의 흐름축에 수직한 횡방향 및 수심방향에 대하여 기본방정식들을 적분함으로 3차원 문제를 1차원 문제로 치환하는 적분해석법을 사용하였다. 다만 이 일이 가능하기 위해서는 유동변수들(유속, 밀도 등)의 횡방향 및 수심방향의 분포함수가 알려져 있음이 전제되어야 하는데 유속의 축방향성분 및 플룸과 주변수 간의 밀도차가 상기 두 방향에 대해서 가우스(Gauss)분포를 갖는다는 잘 검증된 가정을 활용하였다. 그리고 이 가정에서 플룸의 횡방향 유속을 도출해낸 본 연구자들의 기발표된 논문의 결과도 활용하였다. 결과로 얻어진 연행(entrainment)효과까지 포함한 방정식들을 Runge-Kutta 수치해석법을 사용하여 풀었다. 그리하여 하천수 풀룸의 3차원적 해석을 쉽게 수행할 수 있는 수치해석기법을 얻어냈다.

• 한국대기환경학회지
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• 제16권2호
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• pp.141-150
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• 2000

In order to genralize the vertical dispersion of plume at long distances on mesoscale over complex terrain dispersion coefficients data have been obtained systematically according to lapsed time after release by using a composite turbulence water tank that simulates convective boundary layer. Dispersion experiments have been carried out for various combined conditions of thermal turbulence intensity mechanical turbulence intensity and plume release height at slightly to moderately unstable conditions. Results of tracer dispersion experiments conducted using water tank camera and image processing system have been converted into atmospheric dispersion data through the application of similarity law. The equation $\sigma$z/Zi=aX/(b+c X2)0.5 where $\sigma$2; vertical dispersion coefficient zi : mixing height X : dimen-sionaless downwind distance was confirmed to be an appropriate and general equation for expressing $\sigma$2 variation with turbulence intensity and plume release height, The value of "a" was found to be principally affected by mechanical turbulence intensity and that of "b" by mechanical turbulence intensity and release height. It was confirmed that the magnitude of "c" varies with release height. Results of water tank experiments on the relationship of $\sigma$2 vs downwind distance x have been compared with actual atmospheric dispersion data such as CONDORS data and Bowne's nomogram Operating conditions of a composite turbulence water tank for simulating the field turbulence situations of CONDORS experiments and Bowne's $\sigma$2(x) nomogram for suburban area have also been investigated in terms of water temperature difference between convection water tank and bottom plate heating tank grid plate stroke mixing water depth length scale and velocity scale. Moreover the effect of mechanical turbulence intensity on vertical dispersion has been discussed in the light of release height and downwind distance. height and downwind distance.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제26권1호
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• pp.43-58
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• 1998

The Kwinana Shoreline Fumigation Experiment (KSFE) took place at Fremantle, WA, Australia between January 23 and February 8, 1995. The CSIRO DAR LIDAR measured plume sections from near the Kwinana Power Station (KPS) stacks to up to about 5 km downstream. It also measured boundary layer aerosols and the structure of the boundary layer on some occasions. Both stages A and C of KPS were used as tracers at different times. The heart of the LIDAR system is a Neodymium-doped Yttrium-aluminum-garnet (Nd:YAG) laser operating at a fundamental wavelength of 1064 nm, with harmonics of 532 nm and 355 nm. For these experiments the third harmonic was used because the UV wavelength at 355 nm is eye safe beyond about 50 m. The laser fires a pulse of light 6 ns in duration (about 1.8 m long) and with an energy (at the third harmonic) of about 70 mJ. This pulse subsequently scattered and absorbed by both air molecules and particles in the atmosphere. A small fraction of the laser beam is scattered back to the LIDAR, collected by a telescope and detected by a photo-multiplier tube. The intensity of the signal as a function of time is a measure of the particle concentration as a function of distance along the line of the laser shot. The smoke plume was clearly identifiable in the scans both before and after fumigation in the thermal internal boundary layer (TIBL). Both power station plumes were detected. Over the 9 days of operation, 1,568 plumes scans (214 series) were performed. Essentially all of these will provide instantaneous plume heights and widths, and there are many periods of continuous operation over several hours when it should be possible to compile hourly average plume statistics as well. The results of four days LIDAR observations of the dispersion of smoke plume in the TIBL at a coastal site are presented for the case of stages A and C.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.51-54
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• 2002

When a cold HPSI (High Pressure Safety Injection) fluid associated with an design basis accident, such as LOCA (Loss of Coolant Accident), enters the cold legs of a stagnated primary coolant loop, thermal stratification phenomena will arise due to incomplete mixing. If the stratified flow enters a reactor pressure vessel downcomer, severe thermal stresses are created in a radiation embrittled vessel wall by local overcooling. Previous thermal-mixing analyses have assumed that the thermal stratification phenomena generated in stagnated loop of a partially stagnated coolant loop are neutralized in the vessel downcomer by strong flow from unstagnated loop. On the basis of these reasons, this paper presents the thermal-mixing analysis results in order to identify the fact that the cold plume generated in the vessel downcomer due to the thermal stratification phenomena of the stagnated loop is affected by the strong flow of the unstagnated loop.