• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 추계학술발표회요약집
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• pp.135-135
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• 1998

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.107-112
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• 2001

The effect of ambient gas (steam) condensation on swirl spray characteristics were studied experimentally for low subcooling condition of the liquid. The configuration of the liquid(water) sheet and the breakup modes were examined. Also variation of the discharge coefficient, breakup length, local and the cross-sectional area-averaged SMD of droplets with the liquid flow(injection) rate were obtained. The perforation breakup mode appears dominant with condensation while the aerodynamic wave breakup mode is dominant without condensation(in the air environment). The discharge coefficient, breakup length and the mean drop sizes decrease in a same manner with increasing of the liquid flow rate for both cases(with and without condensation). The condensation effects are insignificant with the discharge coefficient. However, the local and cross-sectional area-averaged SMD are larger and the breakup length becomes shorter in the steam environment. The spray angle predicted from the volumetric flux distribution along the radial direction of the sprays in the steam environment becomes larger with condensation.

• 한국분말재료학회지
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• 제9권1호
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• pp.32-37
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• 2002

In the present study of IGC (Inert Gas Condensation) evaporation-condensation processing study, the effects of IGC convection gas on the crystallographic structure, size and shape of tin oxide nanoparticles were investigated. In addition, the phase transformation of tin oxide nanoparticles was studied after heat treatment. IGC processing was conducted at 1000℃ for 1 hr. The mixture gas of oxygen and helium was used as a convection gas. Metastable tetragonal SnO nanoparticles were obtained at a lower convection gas pressure, whereas amorphous tin oxide nanoparticles were obtained at a higher one. The formation of amorphous phase could be explained by the rapid quenching of the vaporized atoms. The resultant nanoparticles size was about 10 nm with a rounded shape. The tin oxide nanoparticles prepared by IGC were almost transformed to the stable tetragonal SnO₂ after heat treatment.

• 대한기계학회논문집
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• 제18권10호
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• pp.2675-2685
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• 1994

A study has been conducted to provide the experimental information for the velocity and temperature profiles of steam-air mixutre and to investigate their roles on the film condensation with wavy interface. Saturated gas mixture of steam-air was made to flow through the nearly horizontal$(4.1^{\circ})$ square duct of 0.1m width and 1.56m length at atmospheric pressure, and was condensated on the bottom cold plate. The air mass fraction in the gas mixture was changed from zero(W =0, pure steam) to one(W =1, pure air), and the bulk velocity was varied from 2 to 4 m/s. Water film was injected concurrently to investigate the effect of wavy interface on the condensation. The velocity and temperature profiles were measured by LDA system and thermocouples along the three parameters ; air mass fraction, mixture velocity and film flow rate. The profiles moved toward the interface with increasing steam mass fraction, mixture velocity and film flow rate. The Prandtl and Schmidt numbers were near one in the present experimental range, however there was no complete similarity between the velocity and temperature profiles of gas mixture. And the heat transfer characteristics and interfacial structure were coupled with each other.

• 한국항공우주학회지
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• 제35권3호
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• pp.248-252
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• 2007

본 연구는 공급계 관에서 극저온 연료의 일부가 기화될 경우에 로켓엔진이 지속적으로 작동될 수 있는지의 여부를 묻는 문제와 관련되어 있다. 유동장 내에 증기가 발생하는 것을 모사하는 실험의 결과분석으로 관내의 압력조건에서 극저온 유체의 온도가 포화온도보다 낮을 경우 발생된 증기가 완전히 응축될 수 있다는 것을 확인하였다. 극저온 유체의 정상유동에서 비평형 응축영역을 계산하기 위한 경험관계식을 무차원형태로 구하였고, 이 경험관계식이 실제적으로 활용 될 수 있는 분야를 제시하였다.

• Nuclear Engineering and Technology
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• 제31권5호
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• pp.465-475
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• 1999

The objective of the present work is to assess the analysis capability of two wall film condensation models, the default and the alternative models, of RELAP5/MOD3.2 on condensation experiments in the presence of noncondensable gas in a vertical tube of PCCS of CP-1300. In the calculation of a base case the default model of RELAP5/MOD3.2 under-predicts the heat transfer coefficients, and Its alternative model over-predicts them throughout the condensing tube, Also, both models over-predict the void fractions. The nodalization study shows that the variation of the node number does not change both modeling results of RELAP5/MOD3.2 Sensitivity study for varying input parameters shows that the inlet steam-air mixture flow rate, the inlet air mass fraction, and the inlet saturated steam temperature give significant changes of their heat transfer coefficients Run statistics show that the grind time of the default model is always higher than that of the alternative model by about 23%.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(1)
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• pp.383-388
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• 1995

Two-phase transient phenomena in the noncondensable gas-filled closed loop was investigated numerically using the RELAP5/MOD3 version 3.1 computer code. The condensation heat transfer correlation for noncondensable gases was studied in detail. Two modes of the reflux condensation which can be characterized by countercurrent flow of steam and its condensed water and the oscillatory between reflux condensation and natural circulation were predicted well. However, the natural circulation mode which the condensed water carried over the U-bend concurrently with steam was failed to predict.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.517-524
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• 2018

본 연구의 목표는 수평 관외 초소수성 튜브에서 비응축가스(NCG)의 영향을 관찰하고, 이를 일반 알루미늄 튜브의 응축 현상과 비교하는 것이다. 초소수성 튜브 제작을 위해 Self-Assembled Monolayer(SAM) 코팅으로 알루미늄 튜브의 외부를 표면개질 했다. 응축 성능을 나타내기 위해 총합 열전달계수를 사용하였고, 이 값으로 응축 성능을 비교 검토하였다. 본 연구의 주요 변수는 비응축가스 질량 분율로, 0.08에서 0.45의 범위에서 실험을 진행하였다. 응축 실험을 통해 비응축가스 질량 분율이 낮아질수록 응축 성능이 SAM 튜브와 일반 튜브에서 모두 향상되는 것을 확인했다. SAM 튜브에서 적응축 열전달 성능은 일반 튜브 대비하여 평균 약 1.9배에서 2.5배 정도 큰 것을 관찰하였다. SAM 튜브에서 비응축가스 질량 분율이 낮아지면서 응축 성능 상승폭이 감소하게 되는데, 이는 Flooded 응축 현상이 발현되었기 때문이다. 응축이 더 활발하게 진행되면 SAM 튜브에서 막응축이 일어나는 것을 관찰하였고, 이 때 성능은 일반 알루미늄 튜브보다도 저하된 성능을 보였다. SAM 알루미늄 튜브에서 Flooded 응축과 막응축이 일어나는 원인으로 표면에서의 Pinning 효과를 이용하여 설명하였다. 결론적으로, SAM 튜브를 실제 응축기에 적용해 표면개질로 인한 응축 성능 개선 효과를 얻기 위해서는 적응축 또는 Flooded 응축이 일어나는 조건으로 응축기 내 환경 조성을 해야 한다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 춘계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.49-49
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• 2006

• 한국분말재료학회지
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• 제9권6호
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• pp.409-415
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• 2002

In this review the methods for production and processing of isolated or agglomerated nanoscale metal particles embedded in organic liquids (nanosuspensions) and polymer matrix composites are elucidated. Emphasis is laid on the techniques of inert gas condensation (IGC) and high pressure sputtering for obtaining highly porous metal powders ("nanopowder") as well as on vacuum evaporation on running liquids for obtaining nanosuspensions. Functional properties and post-processing are outlined in view of applications in the fields of electrically conductive adhesives and anti-microbially active materials for medical articles and consumer goods.mer goods.