• Journal of Korea Water Resources Association
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• v.38 no.5 s.154
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• pp.365-377
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• 2005

This paper presents numerical works carried out for developing an advanced computational framework for understanding injury- and mortality-inducing flow phenomena in hydropower facilities. Large-eddy simulation (LES) of a circular jet flow is carried out to help interpret the results of recent experiments that exposed live fish to the shear zone of a turbulent jet. The instantaneous flow field of LES is characterized by intense velocity, pressure, and vorticity fluctuations, which could exert forces and moments on a fish considerably larger than those exerted by the same fish exposed to the corresponding steady, time-averaged flow. In this study, also, unsteady modeling of flow in a hydroturbine draft tubewas carried out using a hybrid unsteady RANS/LES, so-called detached-eddy simulation (DES). Results from DES show that the potential for disorientation and excessive residence times of fish within the draft tube is certainly considerable.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1162-1167
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• 2006

Because the mixing efficiency is influenced remarkably by varying the geometrical configurations, the study of flow characteristics inside the agitator is very important. The draught tube in the agitator makes intermixing between the screw and tube by interrupting radial flow, and the helical screw agitator with a draught tube (HSA) is proved more efficient to mix than the others. Consequently, the shapes of helical screw and number of pitches are the main parameters for improving the performance of HSA. In this study, numerical analyses were carried out, using a commercial CFD code, Fluent, to obtain the velocity and pressure distributions under steady, laminar flow and no-slip condition. Results are graphically depicted with various parameters.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.75-79
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• 1999

순환유동층은 주탑에서 비말 동반된 입자를 cyclone과 같은 입자 포집장치에서 회수하여 다시 주탑으로 재 주입함으로써 입자의 순환이 일어나는 외부 순환계와 종래의 유동층내에 원형관(Draft tube)이나 평판을 설치하여 두개의 층으로 분리한 후 가스 분산판 위의 간격을 통해 입자들을 두 구역 사이로 강제 순환시키는 내부순환계로 분류할 수 있다. 드래프트 관을 갖는 내부순환유동층 반응기는 기체와 고체의 적절한 접촉을 통해 반응이 이루어지는 반응기 형태이다.(중략)

• The KSFM Journal of Fluid Machinery
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• v.10 no.1 s.40
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• pp.56-63
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• 2007

Because the mixing efficiency is influenced remarkably by varying the geometrical configurations, the study of flow characteristics inside the mechanical agitator is very important to improve the performances. The draught tube in the agitator makes intermixing between the screw and tube by interrupting radial flow, and it makes circulation region in a mixing chamber. In general, the helical screw agitator with a draught tube (HSA) is proved more efficient to mix than the others. Consequently, such as the shapes of helical screw, number of pitches and the variation of angular velocity are the main parameters for improving the capacity of HSA. And also the suspension of the solid particles in the agitator can be determined these parameters. The rate of solids suspension in the mixing chamber was quantified with a statistical average value, of. Numerical analyses were carried out, using a commercial CFD code, Fluent, to obtain the velocity, pressure and particle distributions under steady, laminar flow and no-slip conditions. Results are graphically depicted with various parameters.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.71-74
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• 1999

최근 들어 자동차 보유대 수의 급격한 증가와 함께 폐타이어의 발생량도 급격히 증가하였다. 폐타이어의 발생량이 적었을 때는 매립이나 소각 등의 방법으로 폐타이어를 처리해도 별 문제가 발생하지 않았다. 그러나, 폐타이어 발생량이 급격히 증가한 요즈음은 발생된 폐타이어가 합법적으로 처리되어지지 못하고 야적, 방치, 불법 매립 및 소각 등의 방법으로 처리됨으로써 환경적인 오염뿐만 아니라 시각적 공해, 대기 오염 등의 문제를 심각하게 야기 시키고 있다.(중략)

• Journal of the Society of Disaster Information
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• v.13 no.4
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• pp.529-536
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• 2017

In this study, the perceptions were surveyed fire risk and flash flames concerning the firefighters. The results were statistically evaluated according to age, experience and rank. More than 70% of the respondents answered that there is a possibility of unexpected flame exposure in the field of fire, but there was no recognition difference according to age, experience and rank. However, if there is an emergency situation in the field of fire, the survey on the ability to cope with crises showed that there is a difference in perception depending on the age, career, and rank of respondents. From these results, it is expected that strengthening simulation training of unexpected situation will be more urgently required in the future, and measures should be taken to minimize human accidents through improvement of standard operation procedures or supplement of fire suppression education according to unexpected situation.