• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1170-1178
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• 2007

Repeated hardware tests and tuning, investing cost and time, are usually required to assure a satisfactory performance of the suspension seat. In this study, an EILS(ECU-in-the-loop) method was proposed to develop a controller for a semi-active suspension seat with a MR(magneto-rheological) damper. EILS system was developed using a real-time seat dynamics model communicating with ECU hardwares under a closed loop environment utilizing Matlab/Simulink and xPC $TargetBox^{TM}$. A sky-hook based control algorithm with optimized damping coefficients was verified to reduce the energy consumption and to improve the vibration response performance.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.961-964
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• 2010

A semi-empirical fluctuation term is presented to improve a classical equation of state (EOS) for volumetric properties in the critical region. The term is based on the two assumptions: (1) The Helmholtz energy is individually divided into classical and long-range density fluctuation contribution (2) All molecules form cluster near the critical region due to long-range density fluctuation. To formulate such molecular cluster, we extended the Veytsman statistics originally developed for the cluster due to hydrogen bonding. The probability function in the statistics is modified to represent the characteristics of long-range density fluctuation vanishing far from critical region. The proposed fluctuation contribution was incorporated into the Sanchez-Lacombe EOS and the combined model with 6 adjustable parameters has been tested against experimental VLE data. The combined model is found to well represent flatten critical isotherm for methane and top of the coexistence curve for the tested components. The prediction results for caloric data are in good agreement with the experimental data.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.9-18
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• 2003

In this work, a closed-form analysis is performed for the structural response of coupled composite blades with multi-cell sections. The analytical model includes the effects of shell wall thickness, transverse shear, torsion warping and constrained warping. The mixed beam approach based on Reissner's semi-complementary energy functional is used to derive the beam force-displacement relations. The theory is validated against experimental test data and other analytical results for coupled composite beams and blades with single-cell box-sections and two-cell airfoils. Correlation of the present method with experimental results and detailed finite element results is found to be very good.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.05a
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• pp.121-127
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• 1996

To compare the performance of aluminized solid propellants, the theoretical calculation was performed for the propellants using HTPB and PEG binder and four kinds of oxidizers such as AP, HMX, ADN, and HNIW. PEG/HMX/Al and PEG/HNIW/Al showed the maximum performance at 17% of aluminum level and there was no difference in maximum performance when HMX was partially replaced with AP in PEG/HMX/AP/Al propellant. The order of performance magnitude of various propellants which the specific impulse loss calculation was considered by semi-empirical equation was like the following; PEG/HNIW/AI>[$\frac{PEG/HMX/AI}{PEG/HMX/AP/AI}$>HTPB/AP/AI>PEG/ADN/AI

• Bulletin of the Society of Naval Architects of Korea
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• v.25 no.4
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• pp.1-6
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• 1988

In this paper two-dimensional breaking waves of plunger type are numerically simulated both on an even bottom and on a sinusoidally-varying bottom within the framework of potential theory. Based on the boundary integral method derived by Vinje and Brevig, fluid particles on the free surface are treated exactly by using semi-Lagrangian time-stepping. Numerical instability, in particular when the wave front becomes vertical, is discussed and the regriding method of nodal points has been found promising. Numerical accuracy is examined in terms of the wave energy and mass conservations. It is also found that the bottom topography affects significantly and the hydrostatic pressure contributes considerably to the nonoscillating force acting on the bottom, when waves are breaking.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.109-116
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• 1999

To establish optimum cycle of the inverter-driven heat pump with a variation of frequency, the bypass orifice, which is a short tube having a bypass hole in the middle, was designed and tested. Flow characteristics of the bypass orifice were measured as a function of orifice geometry and operating conditions. Flow trends with respect to frequency were compared with those of short tube orifices and capillary tubes. Generally, the bypass orifice showed the best flow trends among them, that will enhance the seasonal energy efficiency ratio of an inverter heat pump system. Based on experimental data, the semi-empirical flow model was developed to predict mass flow rate through bypass orifices. The maximum difference between measured data and model's prediction was within ${\pm}5%$.

• Journal of the Korean Chemical Society
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• v.7 no.2
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• pp.159-164
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• 1963

The astatine isotopes produced in $He^3$ bombardment of bismuth were analysed with alpha ionization chamber and 100 channel pulse height analyser. The main product was $At^{209}$ formed by ($He^3$, 3n) reaction. Four other isotopes were also identified. Semi-quantitative calculation of relative yield of each isotope was attempted.

• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.90-94
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• 1988

본 논문은 반 잠수식 시추선과 선박과의 충돌해석에의 정적 압축법의 응용에 대해 다루었다. 선박이 시추선의 취약 부재에 충돌하는 경우를 가정하였으며 이 취약한 부재의 충돌에너지 흡수능력을 상세 해석 없이 추출하는 방법으로, 관련된 구조물 전체 강성 매트릭스를 부재의 양단에 정적 압축을 시켜 양단 유연도를 추출한 뒤 이 유연도를 양단에 가진 원통형 부재를 해석함으로써 외력-변형 관계를 얻을수 있었다. 충돌에너지 양은 외력-변형 선도를 적분함으로써 얻을 수 있다. 새로운 방법에 의한 결과를 3차원 수치해석 방법과 강체 프라스틱 방법에 의해서 얻어진 결과와 상호 비교하였으며, 이 새로운 방법이 해양구조물 충돌해석이 매우 효과적으로 응용될 수 있음을 알게 되었다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.271-276
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• 2014

LED lighting has received worldwide attention as advantages, such as environment-friendly than the conventional light, the excellent energy efficiency, and a semi-permanent lifetime. The use of the SMPS increased with the rapid growth in the LED industry. Increased use of SMPS means an increase in the harmonic generation load. Therefore, LED lighting compared with conventional fluorescent lamps were tested in this paper for characterized by a light source, electrical and harmonic characteristics. Experiments results for LED lighting showed different characteristics from the existing fluorescent lamp. Especially harmonic characteristic results showed different characteristics in accordance with the power device manufacturing method for LED lighting.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.09a
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• pp.3-12
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• 2006

The main feature of these total technologies is that we can constitute the optimum treatment scheme fitting to the property of wastes, amount of wastes and energy requirement. For high moisture content wastes or biomass resources, high pressure steam process (MMCS) for crush, dry and deodorize wastes to produce high quality fertilizer of fuel is most appropriate. For dry or semi-dry solid wastes, the STAR-MEET system can be applied to produce low-BTU gases for power generation using duel fueled diesel engines of Stirling engines, and the REPRES and HyPR-MEET systems can be applied to produce hydrogen rich medium-BTU gas. For waste plastics and oils, liquefaction technology is best fit to produce light oil or kerosene equivalent fuel oils. These total technologies are completely different from the existent waste treatment technologies based on land-filling or incineration, and are expected to disseminate all over the world in the near future.