• The Microorganisms and Industry
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• v.35 no.2
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• pp.10-13
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• 2009

• Nuclear Engineering and Technology
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• v.24 no.3
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• pp.311-318
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• 1992

During mid-loop operation of Nuclear Power Plant, to prevent the Decay Heat Removal System (DHRS) from failure due to air entrainment of free surface vortex in the piping system, a set of simulating experiments was performed. Through these experiments, a relation between the non-dimensionalized numbers, such as H/d, Froude number, Reynolds number, was found. It was also found that the perturbation of the system by the disturbance such as pump start, valve operation, etc., has a strong effect on the free surface vortex. Furthermore, from viewpoint of reactor safety, a modified inlet device which is reducer type is strongly recommended for the prevention of air entrainment into DHRS.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.5
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• pp.474-481
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• 1997

Waterjet propulsion generally refers to propulsion of ships by internally mounted pumps with proper ducting. This arrangement of the actuator component of the system leads to the fundamental differences with respects to screw propeller system. In this paper, the basic hydrodynamic characteristics of waterjet propulsion was outlined to clarify the application consideration and proposal for carrying out model self-propulsion tests with waterjet propelled models was presented. The results of model self-propulsion tests carried out in the Hyundai Maritime Research Institute towing tank with catamaran ship were presented.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.42-47
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• 1996

기존의 우회배관을 제거하고 원자로냉각재배관에 직접 RTD를 삽입하여 온도를 측정할 경우 취수부내의 유속이 기존에 비해 어떻게 변하는지 고찰하고자 한다. 이는 RTD응답시간 요건을 만족하기 위해서는 RTD SCOOP 내부유속이 3ft/sec이상이 되어야만 하기 때문에 중요하다. 이러한 유속을 계산하기 위해 취수부를 단순화하고 보수적인 가정에 의해 유체역학적으로 계산한 결과 이러한 요건을 만족하는 결과를 얻을 수 있었다. 또한 흡입구와 출구 Hole에서 차압의 대부분이 발생하므로 이부분의 부차계수가 유량계산에 절대적으로 영향을 미치고 있으며 아울러 원자로냉각재유량의 크기에 따라 미치는 영향을 계산한 결과 거의 비례적으로 증가하고 있으며 출구직경을 확대하므로 유량을 3.5 ft/sec까지 증가시킬 수 있다는 결과를 얻었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.62-63
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• 2002

램젯 엔진을 장착한 미사일은 기존의 터보젯 이나 터보팬 엔진에 비해 압축기와 터빈과 같은 엔진 구성품이 없어 무게가 가볍고 초음속에서 저항도 적으며 고속의 비행영역에서 연료효율과 생존성능이 뛰어나기 때문에 차세대 미사일 추진 시스템으로서 세계 여러 국가에서 개발 및 운용이 이루어지고 있다. 하지만 램젯 엔진은 충분한 램 효과를 얻어야 초기 점화가 가능하기 때문에 현재 개발되고 있는 대부분의 시스템은 최초 발사시 로켓 부스터에 의해 가속하고 로켓연료를 모두 소모하고난 후에 흡입구가 개방되어 램젯 엔진이 점화하는 방식을 취하고 있다.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.97-108
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• 2018

It is definitely important to measure thrust during ground test when developing air-breathing engine, and in case of air-breathing engine, gross thrust should be calculated considering not only the measured thrust but also the force induced by the air flow of engine intake. Also, side thrust like yaw and pitch should be measured and analyzed using multi-component thrust measurement system. Engine performance was accurately evaluated by calculating the gross thrust of air breathing engine precisely which is analyzed from below serial procedure: labyrinth seal isolation, 1-axis gross thrust calculation, develop multi-component thrust measurement system, and side thrust analysis.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.633-644
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• 2016

The purpose of this study was to examine the effect of phytoncide Aroma inhalation and exercise combination therapy on the college life stress, mood state and sleep pattern of the university students. Participants were 72 college students of four groups of Phytoncide Aroma Inhalation group(n=18), Exercise group(n=17), Phytoncide Aroma Inhalation and exercise combination therapy group(n=17), control group(n=20). Research subjects pre-test(0week), mid-test(6week), post-test(12week) measurement was made equally on college life stress, mood state and sleep pattern. As a result, mood status, college life satisfaction and sleep scores were improved in all groups except the control group. Especially, phytoncide inhalation and exercise combination therapy group showed the greatest change in scores.

• The KSFM Journal of Fluid Machinery
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• v.4 no.4 s.13
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• pp.7-15
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• 2001

Flow analysis was carried out for a double-suction centrifugal pump. Impeller-only models and a full pump model were used to simulate the velocity field and the pressure field of the pump. Heads and efficiencies were calculated with flow rates in order to obtain general performance of the pump. The calculation results were compared to the experimental data, and satisfactory results were obtained. Thus, it may be said that the CFD serves as a useful tool for pump designs.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1834-1839
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• 2003

Temperature and velocity distributions of hot air flows in rotational molding machines with two different shapes and structures of oven and inlet were investigated by using FLUENT, a commercial computational fluid dynamics code. The shape and structure of oven and inlet in current rotational molding machine were improved. Two different sizes of mold inside each oven were considered in the analysis. Temperature and velocity distributions of hot air flows in two different rotational molding machines were compared to each other. In order to reduce cycle time and improve product quality in current rotational molding machine, the improved shape and structure of oven and inlet were proposed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.4
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• pp.253-260
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• 2013

Ice accretions on the surface around a rotorcraft air intake can deteriorate the safety of rotorcraft due to the engine performance degradation. The computational simulation based on modern CFD methods can be considered extremely valuable in analyzing icing effects before exact but very expensive icing wind tunnel or in-flight tests are conducted. In this study the range and amount of ice on the surface of anti-icing equipment are investigated for heat-on and heat-off modes. It is demonstrated through the computational prediction and the icing wind tunnel test that the maximum mass and height of ice of heat-on mode are reduced about 80% in comparison with those of heat-off mode.