• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.35-40
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• 2011

An experimental study of the flame response in a turbulent premixed combustor has been conducted in order to investigate mechanisms for combustion instabilities in a lean premixed gas turbine combustor. A lab-scale combustor and mixing section system were fabricated to measure the flame transfer function. Measurements are made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results show that the flame transfer functions are greatly dependent on the modulation frequency as well as operating conditions such as equivalence ratio. Flame dynamics can be generalized as a function of Strouhal number which is a ratio of flame length to modulation wave length.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.430-432
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• 2011

An experimental study of the flame response in a turbulent premixed combustor has been conducted in order to investigate mechanisms for combustion instabilities in lean premixed gas turbine combustor. A lab-scale combustor and mixing section system were fabricated to measure the flame transfer function. Measurements are made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results are analyzed to determine the phase and gain of the flame transfer function as a function of the modulation frequency and operating conditions.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.159-167
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• 1999

Sandwich injection molding is one of the remarkable polymer processes recently developed from conventional injection molding. But it is almost impossible to do theoretical investigation that we've researched it through numerical simulation. In this paper, numerical simulation on the study of sandwich injection molding is based on Finite Element Method and FAN/Control Volume method. In addition to conventional filling parameter that can confirm skin polymer melt front, new filling parameters have been introduced to confirm core polymer melt front advancement. These filling parameters are defined in each layer which is divided to solve temperature field along the thickness direction. One can notice different filling patterns resulted from the variation of material properties such as viscosities and power-law indexes, and processing conditions such as switch-over times and wall temperatures. It gives us a better understanding of the sandwich injection molding process. And we can recognize that it's the core polymer spatial distribution after the completion of filling that is the most important key point to use this process for industrial molding process.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.7-11
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• 1985

Underwater ambient noise in the depth 5m to 200m layers was measured at 14 point from the 24th of July to 2nd of August, 1984, in the Korean east sea areas. The underwater ambient noise pressure level was depended upon configuration of the sea bottom and sea condition, which was formed type of prevaling noise at a long distance from coast and type of intermittent and regional noise at a short distance from coast.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.602-606
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• 2007

어도 설계시 실무자의 입장에서 많은 어려움을 가지고 있다. 대부분의 수공구조물 설계인자가 기상학적 인자에서 도출되는 반면에 어도는 어류의 이동특성이나 유영능력 등 생태학적 인자에서 설계되어져야 하기 때문이다. 그러나 충분한 기초자료의 부족이나 설계자가 좋은 구조물을 지어야 한다는 사명감 부족 등으로 대부분의 어도가 기존 어도의 형태를 답습하는 형태로 건설되고 있다. 본 논문은 한강의 잠실수중보 어도설치계획을 근간으로 하여 어도를 설계하는데 필요한 세 가지 요소를 제안하였다. (1) 공간적 위치나 정열이 부적정한 어도의 수정할 점 (2) 어류의 이동특성이나 유영능력에 적합한 pool형 어도의 월류 수심을 3차원 수치모형계산을 통하여 제시 (3) 어도입구에 고기를 모일 수 있게 하는 유인수로의 필요성

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.28 no.1
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• pp.31-37
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• 1999

최근의 건축물은 입구부분에 외부의 광장개념을 실내로 유입시켜 이용객에게 개방감을 주면서 휴식공간을 제공하고자 하는 아트리움 또는 대공간의 형태가 자주 계획되어 지고 있다. 인천국제공항의 첫 관문이자 교통시설의 중심 역할을 하게 될 교통센타에서도 바닥면적 28,000$m^2$, 높이 약45m규모의 대공간이 계획되었으며, 그의 외부형태는 그림 1과 같이 항공기와 새의 모습을 형상화하고 있다. 인천국제공항 단지 내에 위치하고 있는 교통센타는 연면적 9만5천평의 규모로서 앞서 설명한 대공간의 홀과 각종 판매시설, 주차장, 철도역사시설 둥을 갖추고 있다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.157-170
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• 2002

To examine the structure and distribution of the Keum River plume produced by continuous river discharge we carried out three-dimensional numerical model experiments with or without Coriolis force and tide. When Coriolis force is included but tide is not the model plume forms the clockwise circulation north of southern channel in the developing stage. As the plume expansion progresses the center of circulation moves to the southwest, with fuming the discharging axis of low-salinity water to the southwest from the mouth of southern channel. These results are explained mainly in terms of barotropic geostrophy by surface slope maintained with accumulated low-salinity(buoyant) water in front of the estuary mouth due to of offshore strong salinity front. When the M$_2$ tide is included the model plume extends farther to the northwest, forming large tongue-like salinity distribution. The tidally averaged surface flows of the offshore plume are mainly in geostrophic balance. These changes in plume distribution are explained in terms of low-salinity water advection by tidal excursion and active tidal mixing; the former supplies low salinity water to the north off the estuary mouth and the later increases mean sea level along the plume and surface salinity in northern shallow coastal area. The main features of observed Keum River plume(Lee et al., 1999; Choi et al., 1999), which showed the northwestward deflection of the plume axis and northward deepening of the plume thickness from the estuary mouth region, are well reproduced by the model in which tide is included.

• Solar Energy
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• v.16 no.2
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• pp.113-122
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• 1996

This study presents experimental results of heat transfer characteristics of P.C.M. during outward melting process in a vertical cylinder. The experiment was carried out in six conditions, i. e., three different inlet temperature($7^{\circ}C,\;4^{\circ}C\;and\;1^{\circ}C$) and two directions of working fluid(upward and downward). Melting P.C.M. produced a bell-shaped phase change interface. When the inlet temperature was $7^{\circ}C$, the lower region remained at $4^{\circ}C$ until the temperature of upper region reached $4^{\circ}C$. This was due to the state of maximum density of the lower region. When the direction of the working fluid in the case of $7^{\circ}C$, inlet temperature, was upward, the rate of melting and the total melting energy were higher than when it's direction was downward. But the rate of melting and the total melting energy appeared higher value as it's direction was downward when the inlet temperature is $4^{\circ}C$ and $1^{\circ}C$.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.107-114
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• 2019

In many military aircraft, s-shaped diffusers are used to prevent the fan blades of the turbofan engine from being exposed to the outside. The inlet configurations of the air intakes for military aircraft vary, such as the rectangular intake of the F-22, the crescent-like intake of the F-16, elliptical intake of the MQ-25. In this study, the aerodynamic performance of s-shaped diffusers with various inlet configurations was evaluated using numerical analysis. In addition, the configuration of the middle section of an s-shape duct was changed to the crescent shape, and the effects on its aerodynamic performance were investigated. As a result, there was a slight difference in total pressure recovery according to various inlet configurations with ellipse-shaped middle sections. Also, the total pressure distortion was the lowest in the rectangular inlet shape. When the configuration of the middle section was changed from an ellipse to a crescent shape, the total pressure recovery remained at a high level, except for the ellipse-shaped inlet configuration. In terms of total pressure distortion, the duct with the crescent-shaped middle section showed a significantly more uniform pressure distribution than that with the ellipse-shaped middle section.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.230-237
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• 2011

In this study, the characteristic of fluid flow in the new type lung assist devices has been established using computational fluid dynamics(CFD). For the modeling, the hollow fiber was ignored, and vertical types and tangential types were used for the model. Which was to analyze the flow characteristics of the fluid flow model when there exists 1 and 2 input/output ports, and when the input/output ports is located at the center of the cylinder and at the tangential direction with the cylinder wall. The modeling results showed that it was possible to eliminate no-flow region(stagnant layer) as shown in the vertical type when an inlet and an outlet were installed on the tangential direction of the cylinder as shown in the tangential type. Also, in the tangential type, vortex-type flow appeared as dominant, and it showed a complicated flow not deviated to one side. When the number of input/output was two, there was no deviated flow, and complicated flows were generated all across the tube. From the test result, it was found that input/output of flow was tangential type and complicated flows with no stagnant layer would be generated when there are two inputs/outputs, respectively.