• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.140.2-140.2
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• 2014

인공위성은 우주공간의 고진공 상태와 태양 복사열에 의한 고온 및 극저온이 반복되는 가혹한 환경으로 인해 주요 부품의 기능장애가 초래되므로 발사전 지상에서 열진공 시험장비를 이용한 열진공시험을 수행한다. 위성체의 열진공 시험에 사용되는 열교환기인 베이스플레이트(Baseplate)는 우주 열환경을 모사하기 위하여 직접 방열판 표면에 고온 및 저온의 유체를 공급하여 시험 요구에 따른 필요한 열을 공급하게 된다. 일반적으로 우수한 성능의 위성체 부품의 검증을 위해서 지상의 열환경 시험은 접촉식 히터 및 열교환기를 사용하게 되는데, 이때 적절한 히터 및 블로워 파워를 선정하고 챔버 슈라우드와 열교환에 있어 간섭이 없도록 장비를 운용해야 한다. 본 연구에서는 상용프로그램을 이용하여 열진공 시험용 베이스플레이트에 대하여 전산해석을 수행하였으며, 이를 통해 베이스플레이트 내의 작동 유체의 입구 압력에 의한 열진공 시험용 열교환기의 성능 특성을 관찰하였다.

• Korean Journal of Materials Research
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• v.7 no.7
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• pp.571-575
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• 1997

급냉온도에 따른 전기 저항 측정으로 Cu-17, 25Zn-15AI 및 Cu-17.25Zn-15AI-1Ag형상기억합금의 열처리에 의한 마르텐사이트 변태온도의 영향을 연구하였다. DSC 측정으로 고온 모상에서의 상전이 온도롸 종류를 구별하였고 XRD측정으로 구조 변화를 연구하였다. 그리고 열처리에 의한 온도 변화의 원인을 연구하였17.25Zn-15AI 합금에서 고온 모상의 규칙-불규칙 전이온도인 $T_{2}$, $T_{L21}$은 각각 809K와 610K였다. CuZnAI의 경우 $T_{2}$근방에서의 급냉은 마르텐사이트 변태온도를 높이지만 $T_{L21}$ 근방에서의 급냉은 마르텐사이트 변태온도를 낮춘다. 실험결과 열처리에 따른 상전이온도 변화의 원인은 석출물의 형성이라기 보다는 급냉전의 모상의 구조에 가장 큰 영향을 받는다.받는다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.435-436
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• 2019

본 논문에서는 첨단 정밀 전자장치의 신뢰성 시험을 위해 사용하는 온도시험 장비의 오동작이 발생이 되면, 시험담당자에게 문자메시지를 통해 현재 시험장비가 오동작 중임을 알릴 수 있는 시스템을 제안한다. 제안시스템은 기존에 오픈 소스를 이용한 시험장비의 오동작 여부를 모니터를 하는 시스템에 시험담당자에게 이 사실을 SMS로 전달하는 시스템을 추가한 것이다. 정밀 전자장치는 출고전에 온도시험 장비를 사용하여 설정한 저온, 고온 온도 상황에서 각각 정상적으로 장치가 동작하는지의 여부를 확인하게 된다. 만약 이 상황하에서 온도 시험장비가 설정한 저온의 온도 이하 혹은 설정한 고온의 온도 이상 등의 오동작이 발생되면, 수억원에 이르는 고가의 시험대상 제품이 손상을 입어 폐기하는 경우가 생긴다. 제안한 시스템은 시험 운용자가 자리를 비우는 야간에 특히 유용한 시스템으로서 온도시험장비와 별도의 전원을 사용하여 그 신뢰성을 높이는 장점을 가진다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1572-1578
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• 2007

The specified wastes consist of waste acid, waste alkali, waste oil, waste organic solvent, waste resin, dust, sludge, infectious waste, and others. Among these specified wastes, a great portion is liquid phase wastes. The purpose of this study is to develop the high temperature and high pressure (HTHP) treatment system for decomposition of the liquid phase specified waste (LPSW). For this, we analyzed the physical and chemical properties of the LPSW such as density, proximate analysis, ultimate analysis, heating values, and designed 0.3 ton/day HTHP treatment system. The LPSW tested in this experiment were prepared by adding TCE(trichloroethylene) and toluene to liquid phase waste which was brought into the commercial waste treatment company. The average density of waste oil (25 samples), waste resin (5 samples), and waste solvent (12 samples) was 0.99 g/mL, 0.91 g/mL, and 0.93 g/mL, respectively. And the average lower heating value of waste oil, waste resin, and waste solvent was 8,294 kcal/kg, 5,809 kcal/kg, and 7,462 kcal/kg, respectively. The DRE (Destruction & Removal Efficiency) of TCE and toluene were 99.95% and 99.73% at atmospheric pressure conditions and that were 99.99% and 99.82% at pressurized conditions, respectively. These results showed that TCE/toluene mixtures were properly decomposed over about 99.73% of DRE by the HTHP treatment system and pressurized conditions were more effective to destroy those pollutants than atmospheric pressure conditions. Also these systems could be directly applied to industries which try to treat the liquid phase specified waste within the regulation limit.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.3
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• pp.157-172
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• 2010

Using 61 observation data of the recent 30 years from 1979 to 2008, we have identified the areas which had climatologically frequent occurrence of extraordinary low and high temperature leading to meteorological disasters. The station of the highest temperature deviation was Gangneungduring the period of April through July. Furthermore, the eastern coast region including Gangneung recorded the largest amplitude of temperature deviation in Korea, showing the climatological evidence that the temporal variation was the largest. During the period of April to October, most of the days with extraordinary high temperature were found in April. The regionswith more than 30days of extraordinary high temperature werethe eastern and western coast regions. Thus, special attention to prevent the meteorological disaster related to extraordinary high temperature is required in the coast regions particularly during April. Meanwhile, further attention to prevent the disaster related to extraordinary low temperature is required in Gangwon inland, Chungcheong inland, and the southern province especially in August.

• Korean Journal of Materials Research
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• v.10 no.3
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• pp.184-190
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• 2000

We investigated the effect of filler content on the thermo-mechanical properties of modified ACA composite materials by incorporation of non-conducting fillers and the reliability of flip chip assembly on organic substrates using modified ACA composite materials. For the characterization of modified ACA s composites with different content of non-conducting fillers, differential scanning calorimeter (DSC), and thermo-gravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), and thermo-mechnical analyzer (TMA) were utilized. As the non-conducting filler content increased, CTE values decreased and storage modulus at room temperature increased. In addition, the increase in the content of filler brought about the increase of Tg^{DSC}$ and $Tg^{TMA}$. However, the TGA behaviors stayed almost the same. Contact resistance changes were measured during reliability tests such as thermal cycling, high humidity and temperature, and high temperature at dry condition. It was observed that reliability results were significantly affected by CTEs of ACA materials especially at the thermal cycling test. Results showed that flip chip assembly using modified ACA composites with lower CTEs and higher modulus by loading non-conducting fillers exhibited better contact resistance behavior than conventional ACAs without non-conducting fillers.

• Resources Recycling
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• v.16 no.3 s.77
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• pp.44-49
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• 2007

In the present work, the high temperature oxygen pressure leaching behavior of chalcopyrite was studied in sulfuric acid solution. The influence of leaching time, temperature and oxygen partial pressure on leaching process were examined. Leaching rate of copper increased significantly with increasing leaching temperature. Copper recovery reached 87.1% within 2 hours at $200^{\circ}C$ and 10 atm oxygen pressure, while most of the solubilized iron readily re-precipitates as hematite($Fe_2O_3$). It was confirmed that e main leach reaction of chalcopyrite occurred through oxidation with oxygen under oxygen pressure and high temperature(above $150^{\circ}C$). Because sulfur was oxidized entirely to sulfate, passivating elemental sulfur layer was not formed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1455-1462
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• 2010

PHE (Process Heat Exchanger) is a key component required to transfer heat energy of $950^{\circ}C$ generated in a VHTR (Very High Temperature Reactor) to the chemical reaction that yields a large quantity of hydrogen. Korea Atomic Energy Research Institute established the helium gas loop for the performance test of components, which are used in the VHTR, and they manufactured a PHE prototype to be tested in the loop. In this study, as part of the hightemperature structural-integrity evaluation of the PHE prototype, which is scheduled to be tested in the helium gas loop, we carried out high-temperature structural-analysis modeling, thermal analysis, and thermal expansion analysis of the PHE prototype. The results obtained in this study will be used to design the performance test setup for the PHE prototype.

• Composites Research
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• v.16 no.3
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• pp.68-74
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• 2003

In this paper, intermetallic/metal laminated composites have been successfully produced that utilizes SHS reactions between Ni and Al elemental metal foils. The reaction between Ni and Al started from the nucleation and growth of NiA1$_3$ and was followed by the diffusional growth of Ni$_2$A1$_3$ between Ni and NiA1$_3$. The SHS reaction was thermodynamically analyzed through the final volume fraction of the non-reacted Al related with the initial thickness ratio of Ni:Al and prior heat treatment. Thermally aging these 1aminates resulted in formation of a functionally gradient series of intermetallic phases. Microstructure showed that the intermetallic volume percent was 82, 59.5, 40% in the 1:1, 2:1, 4:1 thickness ratio specimen. Main phases of the intermetallic were NiAl and Ni$_3$Al having higher strength at room and high temperatures.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.9-16
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• 2015

This study was carried out to investigate the effect of delignification on properties of lignocellulose nanofibers (LCNFs) prepared by wet disk-milling (WDM) after steam and ozone oxidation pre-treatments and their nanopaper sheets. Delignification treatment was effective to obtain fine morphology with uniform fiber diameter less than 35 nm without aggregation, and increased the specific surface area (SSA) and filtration time of LCNFs. In particular, SSA and filtration time of the LCNFs prepared by WDM after ozone pretreatment increased 1.5 and 5.4 times after further delignification. Delignification also increased whiteness and decreased the redness of nanopaper sheets. The highest color difference (41.9) before and after the delignification was obtained in LCNFs prepared by WDM after the steam pretreatment. Tensile properties of nanopaper sheets were also increased by further delignification. The highest tensile strength was found to be 142 MPa.