• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.305-308
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• 2005

This paper presents a fabrication of a full-stale combustion chamber of a liquid rocket engine for a ground hot firing test. Engine drawings for manufacturing were prepared after conceptual and detail designs. The combustor is composed of a head and a chamber. SUS316L is used for materials of the head because of the good quality in low temperature. Inner materials of the ablative cooling chamber is silica/phenolic and outer case materials is the SUS316L. Materials of the regenerative cooling chamber are C18200 and SUS316L. After lathe, general milling and MCT machinings, components were finished by electrolytic polishing. A brazing method was applied for bonding the injectors and the injector plate, the regenerative cooling chamber because of structure configurations.

• Fire Science and Engineering
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• v.26 no.5
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• pp.85-91
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• 2012

This paper analyzed firefighting officers' use situations such as the use time, maximum working pressure, hose diameter, etc. of fire pumps at fire sites and carried out various performance tests by pressures, hose diameters and quantities of fire pumps based on its results because the waterproof performance criterion for a fire pump installed in a fire engine is different from the operation situations at the site and is not clearly prescribed. As a result of site survey, the site uses a higher pressure than the standard water discharge pressure (0.85 MPa) or the high-pressure water discharge pressure (1.4 MPa) prescribed by the approval Standard of the fire pump performance on fire truck. In addition, as a result of pump performance test, the discharged water flow rate, water discharge pressure, etc. was measured to be very different from the currently prescribed the approval standard depending on the hose diameter and firefighting nozzle, so the result of this study proposes a new standard.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.880-883
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• 2009

석탄가스화복합발전(IGCC) 시스템에서 합성가스 중에 포함된 황화수소($H_2S$)는 후단의 가스 터빈과 같은 장치의 부식을 방지하고, 합성가스를 이용하는 연료전지 등의 연계 공정에서 요구하는 수준에 맞추어 정제되어야 한다. 본 연구에서는 $H_2S$ 정제공정 추가에 따른 IGCC 시스템의 효율저하를 최소화하기 위하여 고온고압에서 사용가능한 탈황제를 분무건조법을 이용하여 제조하고 제조된 탈황제에 대해 물성 및 황 흡수능 시험을 실시하였다. 형상, 내마모도, 평균입자크기, 충진밀도와 함께 제조된 탈황제가 적용되는 유동층 공정에 적합한 강도를 보유하는지 여부를 미국표준시험방법에 의하여 측정하였다. 황 흡수능은 열중량분석기를 반응기로 사용하여 모사 합성 가스 분위기에서 측정하였다. 분무건조 성형된 탈황제의 일부가 구형이 아닌 타원형 또는 도넛 형태를 나타내고 있어 형상 개선을 위한 제조방법 개선이 필요한 것으로 나타났다. 제조된 탈황제는 기공도가 65% 이상으로 macropore가 기공부피의 대부분을, mesopore가 비표면적의 대부분을 제공하고 있었다. 소성온도를 650 $^{\circ}C$에서 750 $^{\circ}C$로 증가시킴에 따라 대체로 강도가 감소하는 경향을 나타내었다. 열중량분석기로 측정된 황 흡수능은 약 10 wt%로 나타났다. 제조된 탈황제 중 일부는 유동층 공정에 적합한 물성을 보유하고 있었으며 반응성 또한 기존에 개발된 탈황제에 버금가는 성능을 나타내어 향후 공정 적용이 가능할 것으로 분석되었다.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.55-60
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• 2020

The recent semiconductor packaging technology is evolving into a high-performance system-in-packaging (SIP) structure, and copper-to-copper bonding process becomes an important core technology to realize SIP. Copper-to-copper bonding process faces challenges such as copper oxidation and high temperature and high pressure process conditions. In this study, the bonding interface quality of low-temperature copper-to-copper bonding using a two-step plasma treatment was investigated through quantitative bonding strength measurements. Our two-step plasma treatment formed copper nitride layer on copper surface which enables low-temperature copper bonding. The bonding strength was evaluated by the four-point bending test method and the shear test method, and the average bonding shear strength was 30.40 MPa, showing that the copper-to-copper bonding process using a two-step plasma process had excellent bonding strength.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.1-8
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• 2008

The object of this study is to develop the examination technique for measuring the O-ring deformation behavior under the pressure and the squeezed condition simultaneously. The O-ring deformation measuring device in which two grooves were dug to insert the two O-rings was manufactured to be not deformed under the high pressure and the 1 mm and 0.1 mm gap were designed to measure the extrusion lengths under the internal pressure. The beam hardening correction, the histogram analysis and the dead zone correction were executed to exactly measure the shape of O-ring deformation and the lengths of the O-ring deformation were measured by the LSF and the ERF. The computed tomography applied the pressure of 0, 1.378, 4.902, 9.804, 15.692 MPa at 22.3% squeezed condition and the expanded diameter, contact length and extrusion depth were measured in each pressure. The shape of O-ring deformation was evaluated by the FEM to verify the results of measuring by the computed tomography and the area of O-ring was mutually compared to the area measured by the computed tomography.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.11
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• pp.889-902
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• 2020

In this study, a numerical analysis was performed to confirm the formation of supersonic flow and the stabilization time satisfying the design condition in a Direct-connect supersonic combustor. The process was examined in which the high-pressure gas of vitiation air heater propagates downstream to the supersonic combustor and forms a supersonic flow field. It was confirmed through the analysis of pressure and temperature that the supersonic flow field satisfies the design points of Mach number 2.0 and 1,000 K, and requires a minimum of 4.0 ms for stabilization. These results indicate that the time required for the supersonic flow field stabilization should be taken into account when testing for the supersonic combustion experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.87-92
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• 2003

In rocket systems, somtimes special devices or equipments are installed near the nozzle exit area where high temperature and pressure combustion gas flows. To pretect these subsystems from severe thermal environment, it is necessary to have accurate thermal data measured from the experimental liquid rocket firing test. Test variables were combustion pressure (200, 300, 400 psi) and mixture ratio (1.5, 2.0, 2.5) and quartz was used as a heat probe. Measurement technique used in this research can be also applied to measure the radiative heat flux inside the combustion chamber which is important imput data for the liquid rocket regenerative cooling system design.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1195-1201
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• 2010

Performance tests of a supersonic exhaust diffuser were conducted by using a liquid rocket engine for simulating high-altitude environment. The experimental setup consisted of a combustion chamber, a vacuum chamber and a diffuser. The combustion tests for simulating high-altitude environment were carried out at three cases by chamber pressure variation(26, 29, 32barg). The test results showed that the diffuser was started at all case and vacuum chamber pressures were approximately 140torr. The starting pressure using combustion gas was similar with that of cold gas, but the vacuum chamber pressure was relatively high because of high temperature in the vacuum chamber. The results of this test can be used as an essential database for the design of real-scale high-altitude simulation test facility in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.5
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• pp.40-45
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• 2011

In this paper, to develop a broadband power line communication modem and network technologies, we analysis the characteristics of underground power line communication channel through actual tests. To measure the amount of attenuation by length and structure of broadband power line communication channel, we configure a measurement system of the channel with signal generator, spectrum analyzer and non-contacted coupler. For actual tests, we choose two of the longest lines among medium-voltage lines as a single line in the test lines and measure the characteristics of noise and signal attenuation level of the channel. The experimental results show that the channel has a impulse noise which can remarkably reduce communication capability. In the case of long lines, high-frequency attenuation appeared by length of the lines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.536-542
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• 2017

A great deal of difficulty is encountered in the thermo-mechanical analyses of nozzle assembly for solid propellant rocket motors. The main issue in this paper is the modeling of the boundary conditions and the connections between the various components-gaps, relative movements of the components, contacts, friction, etc. This paper evaluated the complex phenomena of nozzle assembly during burning time with co-simulation which include fluid, thermal surface reaction/ablation and structural analysis. The validity of this approach was verified by comparison of analysis results with measured strains.