• Journal of the Korean Society of Industry Convergence
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• v.7 no.2
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• pp.153-159
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• 2004

The purpose of this research is to investigate the performance of swirl combustion chamber diesel engine by changing the jet passage area, the depth and shape of the piston top cavity (main chamber). The performance of diesel engine with newly changed swirl combustion chamber was tested through the experimental conditions as engine speed, load and injection timing etc. The test results were compared and analyzed. And another purpose of this research is to make a new diesel engine that is satisfied fuel consumption and regulation value of exhaust gas. 1. The rate of fuel consumption was affected significantly by the jet passage area at the high speed and load than low speed and low load. The influence of jet passage large area was proven to decrease the rate of fuel consumption. 2. Smoke was affected significantly by the depth of the piston top cavity, but exhaust temperature and the rate of fuel consumption wasn't affected. The rate of fuel consumption was affected by changing injection timing. 3. The rate of fuel consumption, exhaust temperature and Smoke were affected significantly by the shape of the piston top cavity from rectangular to trapezoid. That is we have all high value. The exhaust smoke density and exhaust gas temperature depended sensitively on variation of the injection timing rather than the shape of the combustion chamber within the experimental conditions. 4. We made a new diesel engine that is satisfied design target values(sfc=190 g/hr, NOx + THC=6.0 g/KWh, PM=0.3 KWh), the rate of fuel consumption and emission standard etc., through changing injection timing at the maximum torque point and rated power point. Although we have a little high NOx value.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.282-287
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• 2009

본 논문에서는 사각판이 고정단을 경계조건으로 가진 상태에서 충격력을 받았을 때의 굽힘파 전파와 이에 의한 음향 방사가 특정 공간에서 이루는 음장을 유한 차분 시간 영역법을 이용하여 예측하였다. 이와 같은 시도는 향후 구조물에서의 진동과 음장 사이의 관계를 해석하는데 도움이 될 수 있을 것이다. 대상 시뮬레이션 모델은 한 쪽 끝이 철판으로 이루어진 직육면체의 공간이며 예측 결과를 실험값과 비교하였다. 예측 결과는 대체로 파형과 그 특성이 실험값과 잘 일치하였으나, 감쇠 알고리즘을 주파수 대역에 따라 달리 적용하지 못하였고, 사각 평판에서 충격력의 적용 범위가 모호하여, 파형의 크기에 차이가 있었다.

• Design & Manufacturing
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• v.8 no.1
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• pp.23-26
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• 2014

The injection molding is used in more than 70% of total production of plastic products. Weld line in injection molded part is one of the defects in injection molding process. Weld line deteriorates not only appearance quality but also mechanical property. In this study weld quality has been examined according to the injection processing temperature, materials and mold designs. We selected four different materials such as PA, PP, ABS and PS as experimental materials. Weld quality increased as injection processing temperature increases. It was more dependent on materials flow ability. As a result, weld quality incase of rectangular core is better than circular core.

• The KSFM Journal of Fluid Machinery
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• v.1 no.1 s.1
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• pp.72-80
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• 1998

Computational analysis of incompressible flows by numerically solving Navier-Stokes equations using multi-block finite volume method is conducted on a parallel computing system. Numerical algorithms adopted in this study $include^{(1)}$ QUICK upwinding scheme for convective $terms,^{(2)}$ central differencing for other terms $and^{(3)}$ the second-order Euler differencing for time-marching procedure. Structured grids are used on the body-fitted coordinate with multi-block concept which uses overlaid grids on the block-interfacing boundaries. Computational code is parallelized on the MPI environment. Numerical accuracy of the computational method is verified by solving a benchmark test case of the flow inside two-dimensional rectangular cavity. Computation in the axial compressor cascade is conducted by using 4 PE's md, as results, no numerical instabilities are observed and it is expected that the present computational method can be applied to the turbomachinery flow problems without major difficulties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.521-524
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• 2005

To protect a satellite and electronic equipment from the acoustic loads generated by rocket propulsion system, many launch vehicle use acoustic blanket. Most high frequency region of the acoustic loads is reduced by nose fairing skins and acoustic barrier, but low frequency region is not. In order to control low frequency acoustic mode, we designed away resonator panel which was made of composite materials. This paper shows the absorption coefficient measurement result of resonator and SPL(Sound Pressure Level) reduction by using resonators in a rectangular cavity for experiment. Proper arrangement of acoustic resonators at each mode reduce effectively SPL around the satellite through changing boundary condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.4
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• pp.303-309
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• 2004

Absorptive material arrangement method for effective interior noise control is proposed. Sound field with arbitrary boundary condition is formulated by Kirchhoff-Helmholtz integral equation. A simple example such as a rectangular cavity will present physical meaning between changing boundary condition and control of sound field. The effect of changing boundary condition is expressed in modal admittance. From this formulation. an admittance map is presented. The admittance map is the figure to represent position where absorptive material is attached for effective interior noise control. The admittance map can be assigned to each resonant frequency. There. however, may be common area of those maps. Then, frequency robust arrangement of absorptive material in noise control will be presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.46-50
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• 2001

Due to its ability in producing a net-shape product to high precision in a very shot cycle time, injection molding has become one of the most important polymer-processings in the industry today. Recently the CAE applications in the field of injection molding have provided significant contributions to the mold design and process optimization. As a part of such an application the packing process has been studied using C-PARK. The prediction of pressure variations during post-filling stage for amorphous material has been compared with an experimental observation for a simple rectangular geometry of uniform thickness. And the optimal packing processes were calculated using the cavity pressure curve near the gate. As a case study, a warpage simulation was carried out for a DY-HOLDER with the variable number of gates.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.368-371
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• 2005

In this paper, a small band pass filter is designed using new probe type for wireless communication system. In order to provide a band pass filter which can be reduced in dimension, can be reduced in height, and can be surface-mounted. The filter was fabricated using $TE_{01{\delta}}$ mode dielectric resonator. The input/output probes are attached to coner portion of the rectangular metal cavity. Results of the manufactured filter$(12{\times}12{\times}8mm)$ show that the center frequency is 9.953GHz, the insertion loss is -2.98 dB, the 3dB-bandwidth is 15 MHz, and the lode Q is 663.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.193-201
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• 1995

The role of thermal contact resistance between a casting and a metal mold as well as natural convection in the melt during solidification of a pure metal is numerically studied. Numerical simulation is performed for a rectangular cavity using the coordinate transformation by boundary-fitted coordinate and pure aluminum is used as the phase- change material. The influences of thermal contact resistance on the interface shape and position, solidified volume fraction, temperature field and local heat transfer are investigated.

• Journal of the Korean Ceramic Society
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• v.35 no.7
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• pp.699-705
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• 1998

This paper is about design of optimal structure of microstrip dielectric ceramic antenna with rectangular electrode patches in accordance with the cavity model and fabrication of its prototype sample operating at the frequency of 900 MHz. Results of this work can be employed as a useful too to develop and diversify ceramic antenna having superior performance and omni-directivity to that of current helical antenna.