• 한국항해항만학회지
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• 제32권8호
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• pp.637-643
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• 2008

해양방류시스템을 계획할 때 우선목표는 방류수의 초기희석을 극대화하는 것이다. 이를 효과적으로 달성하기 위해서는 방류수와 주변수의 혼합현상, 특히 초기혼합영역인 근역에 대한 특성분석이 선행되어야 한다. 최근까지 최적의 방류시스템(outfall system) 구현을 위하여 근역(NFR)에서의 온배수 방류에 관한 많은 연구가 이루어지고 있지만 온배수(heat discharge)와 염배수(brine discharge)를 동시에 방류할 경우를 고려한 성과물을 찾기는 어려운 실정이다. 이에 본 연구에서는 온수와 염수를 동시에 고려한 방류시스템의 최적설계를 위한 기초자료를 제공하기 위하여 방류수의 거동양상 특히, 근역에서의 혼합성을 분석하였다. 수치실험은 표면방류, 단일확산관 방류, 다공확산관 방류를 해당 해역의 법적 수질기준에 부합하는지 여부를 주로 평가하였다. 그 결과 표면방류와 단일확산관 방류는 방류형식이 부적절하였고, 다공확산관의 경우도 기하학적인 형상에 따라 결과가 조금 상이하였다.

• 태양에너지
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• 제19권4호
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• pp.21-31
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• 1999

This paper presents a quasi-three-dimensional calculation method considered a spanwise mixing effect in a diagonal flow impeller. The effect of this spanwise mixing caused by spanwise distribution of blade loading is evaluated by a secondary flow theory. In order to verify the validity of this method, it is applied to the analysis of a diagonal flow fan designed under a vortex type of constant circumferential velocity and that of a free vortex. The comparison of the calculated result with experimental data shows a good agreement except the regions near the casing where the flow field is affected by the tip leakage flow.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.513-516
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• 2002

The flow structure and heat transfer characteristics of a turbulent buoyant jet were investigated experimentally. The instantaneous temperature and velocity fields in the near field were measured using a two-frame PIV and PLIF techniques. A thin light sheet illuminated a two-dimensional cross section of the buoyant jet in which Rhodamine B was added as a fluorescent dye. The intensity variations of LIF signal from Rhodamine B molecules scattered by the laser light were captured by a CCD camera after passing an optical filter. By ensemble averaging the instantaneous temperature and velocity fields, the mean temperature and velocity fields as well as the spatial distributions of turbulent statistics were obtained. The results show the flow structure and convective heat transfer of the developing shear layer in the near field.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.218-222
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• 2010

본 연구에서는 ${\sigma}$-좌표계를 기반으로 하는 3차원의 이송확산 모형과 depth-integrated eddy simulation 모형을 결합한 효율적인 3차원 근역 (near-field) 해석모형을 제시하였다. 흐름 모형은 Boussinesq-type equations과 stochastic backscatter model을 기본으로 하고 있다. 이 흐름 모형은 수면의 변화와 바닥으로부터 발생하는 전단력과 파랑의 유동으로부터 발행하는 수심방향의 유속분포를 예측할 수 있다. 이와 같은 흐름 정보를 3차원 ${\sigma}$-좌표계의 이송확산모형에 제공하고 scalar의 이송과 확산에 대한 거동을 계산한다. 기본적인 이송과 이송-확산에 대한 검증 및 개수로에서 정량적 검증과 정성적 검증을 수행하였다. 전반적으로 타당한 결과가 도출되어 모형의 적합성이 있음을 확인하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 추계학술대회
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• pp.153-158
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• 2004

해양에 방류되는 오폐수의 흐름형태 즉 흔합특성을 제어하고 설계하기 위해 다양한 연구가 진행되고 있다. 최근 들어 선진국을 중심으로 바람직한 수질관리를 목표로 법적혼합역과 관련한 수질기준을 정하여 오염무의 방류로 인한 해양수질환경의 오염을 최소화하고자 하는 노력이 진행되고 있다. 본 논문에서는 이러한 근역 및 원역에서의 법적혼합역을 CORMIX 모델로 구현하고 법적혼합역의 필요성을 강조하며 이를 효율적으로 규제하기 위한 방안을 모색하고자 하였다. 이는 보다 개선된 방류수 모델링을 제안하고 나아가 효율적인 해양방류관 설계뿐 아니라 건전한 항만의 설계 및 개발에 기여할 것이다.

• 천문학회지
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• 제38권2호
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• pp.149-151
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• 2005

We have studied the environmental effect on optical-NIR color gradients of 273 nearby elliptical galaxies. Color gradient is a good tool to study the evolutionary history of elliptical galaxies, since the steepness of the color gradient reflects merging history of early types. When an elliptical galaxy goes through many merging events, the color gradient can be get less steep or reversed due to mixing of stars. One simple way to measure color gradient is to compare half-light radii in different bands. We have compared the optical and near infrared half-light radii of 273 early-type galaxies from Pahre (1999). Not surprisingly, we find that $r_e(V)s$ (half-light radii measured in V-band) are in general larger than $r_e(K)s$ (half-light radii measured in K-band). However, when divided into different environments, we find that elliptical galaxies in the denser environment have gentler color gradients than those in the less dense environment. Our finding suggests that elliptical galaxies in the dense environment have undergone many merging events and the mixing of stars through the merging have created the gentle color gradients.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.201-202
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• 2012

The isothermal flow structure and mixing characteristics of a hybrid/dual swirl jet combustor for micro-gas turbine were numerically investigated. Location of pilot nozzle, angle and direction of swirl vane were varied as main parameters with constant fuel flow rates for each nozzle. As a result, the variation in location of pilot nozzle resulted in significant change in turbulent flow field near burner exit, in particular, center toroidal recirculation zone (CTRZ) as well as turbulent intensity, and thus flame stability and emission characteristics might be significantly changed. The swirl angle of $45^{\circ}$ provided similar recirculating flow patterns in a wide range of equivalence ratio (0.5~1.0). Compared to the co-swirl flow, the counter-swirl flow leaded to the reduction in CTRZ and fuel-air mixing near the burner exit and a weak interaction between the pilot partially premixed flame and the lean premixed flame. With the comparison of experimental results, it was confirmed that the case of co-swirl flow and swirl $angle=45^{\circ}$ would provided an optimized combustor performance in terms of flame stability and pollutant emissions.

• 한국환경복원기술학회지
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• 제14권4호
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• pp.55-66
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• 2011

The objective of this study was to investigate the possibility of seeding methods for quarry rehabilitation. To achieve the objective, the experiment was designed for rehabilitation of quarry with seed mixing types (woody type and herbaceous type) and forest topsoil. Seeds and seeding materials were applied to the quarry slope using hydroseeding measures. The study was conducted in limestone quarry (Lafarge Halla Cement Inc.) near Baekdu Daegan Mountain System at Okke, Kanwon-do. The experimental seedbed was set in 2007 and field investigation was carried out from 2007 to 2010. As the result of experiment, it was found that the early-phase pattern for surveyed species to establish was affected by the soil mixture types. The mixture type of herbaceous seeds resulted in the higher plant coverage than the woody seeds. The application of forest topsoil showed a potential increase the plant diversity, but it was affected by mixing seeds. Naturally-emerged species as Alnus hirsuta, Quercus mongolica will be useful for rehabilitation at the quarry and damaged slopes.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2003년도 한국해안해양공학발표논문집
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• pp.199-207
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• 2003

발전소 온배수와 같은 페열의 방류는 여타 방류와는 달리 방류량이 단위 호기당 20-50ton/s 가량으로 매우 크며, 따라서 그 영향을 받는 해역도 매우 크다는 점이 특징이다. 최근 국내에서 시도되고 있는 심층 온배수 방류는 주변수에 비해 밀도가 작은 제트나 플룸의 형성 후 급격한 부력상승과 밀도차에 의한 수평 부력 확장(lateral buoyant spread)이 준 지배적인 현상으로 하수장의 혼합에 비해 즘 더 복잡한 양상을 띄게 된다. (중략)

• 소음진동
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• 제9권1호
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• pp.113-120
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• 1999

A perforated tube nozzle as an exhaust noise suppressor of a high-speed civil transport(HSCT) is proposed. The experimental results for the near and far field sound. the visualization of jet structures and the static pressure distributions in the jet passing through a perforated tube are presented and discussed in comparison with those for a simple tube. It is shown that the perforated tube has an excellent performance to greatly reduce the shock-associated noise and that also the turbulent mixing noise is reduced in the range of a limited jet pressure ratio. This considerable noise reduction is due to the pressure relief caused by the through-flow through the perforated holes. Such a pressure relief results in the transformation of normal shock waves into weak Mach waves of X -type and increases the thrust force of the perforated tube nozzle.