• 구강회복응용과학지
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• 제22권4호
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• pp.289-300
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• 2006

This study was performed to investigate the influence of orthognathic surgery on the temporomandibular dysfunction in skeletal class III malocclusion. The temporomandibular joint status in 22 patients(mean age: 23.7 years) who received orthognathic surgery such as mandibular BSSRO(14 patients), maxillary Le Fort I osteotomy with mandibular BSSRO(8 patients) was evaluated by craniomandibular index. All these patients received orthognathic surgery at least 6 months ago. The mean score and standard deviation was obtained and compared with that of 22 normal individuals(mean age: 24.8years) by Student's t-test. In mandibular movement, the score of orthognathic surgery group was higher than that of the normal group. All the items except mandibular movement did not show any differences between the two groups.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.178.1-178.1
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• 2011

DME is generally expected to be used as a promising clean alternative fuel to diesel fuel. DME is not natural product but a synthetic product that is produced either through the dehydration of methanol or a direct synthetic from syngas. As DME has no carbon-carbon bond in its molecular structure and is an oxygenate fuel, it's combustion essentially generates no soot. DME has such cetane number of 55~60 that it can be used as a diesel engine fuel. However, DME has low lubricity but a proven method to solve the poor lubricity is by adding lubricity improver. Therefore, the aim of this study is to develop lubricity improver of DME as a transport fuel in Korea. In this study, we investigated a possibility of fatty acid ester compounds as a candidate to improve DME lubricity as compared with current lubricity improver of diesel. We also evaluated quality characteristics, storage stability of DME with lubricity additives.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.126-133
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• 2013

Recently, it was reported that complaints about problems being experienced with the performance of vehicles operating on autogas in Korea. The problem was being assumed due to contaminants in LPG and an oily material which was being deposited in vaporizer, injector in LPG fuel system. This study is focused on the analysis of contaminant of automobile parts on LPG fuel system. The sampling points of contaminants are injectors, fuel filters, vaporizer in automobile equipment and it was also investigated by GC-MS, ICP-AES, SIMDIS and EDS. According to results, it was presumed that this contaminants had been analyzed plasticizers with hydrocarbons with high boiling point, Fe from steel corrosion, greases from gas station.

• 한국응용과학기술학회지
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• 제30권3호
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• pp.431-443
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• 2013

Sulfur content of diesel fuel has been cut down to under 10 ppm ULSD (ultra low sulfur diesel) level by environmental regulation with the aim of reducing exhaust emissions. This review discusses the methods and principles of sulfur reduction in diesel and presents an overview of new approaches for ultra-deep desulfurization. The deep HDS (hydrodesulfurization) problems of diesel streams is exacerbated by the inhibiting effect of co-existing aromatics, nitrogen compounds and $H_2S$. The new approaches to deep desulfurization includes non-HDS type processing schemes such as adsorptive, extractive and oxidative desulfurization.

• 한국통신학회논문지
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• 제31권12B호
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• pp.1112-1121
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• 2006

본 연구는 유무선망간 상호접속모형을 다루고 있다. 특히, 발신자 입장에서 착신망 혹은 요금에 대한 무지가 존재하는 경우 상호접속료와 발신요금이 어떻게 책정되는 것인가를 분석하고 있다. 소비자 무지가 존재하는 경우 없을 경우 보다 착신접속료는 더욱더 높으며, 따라서 발신요금도 높아진다. 본 연구에서는 발신요금 상승을 억제 할 수 있는 여러가지 규제적 대안을 비교분석 하고 발신요금과 유무선착신접속료를 동시에 규제할 수 있는 최적 규제방안을 제안한다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.216-223
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• 2005

The coefficient of consolidation has been evaluated using the conventional oedometer tests based on the one-dimensional consolidation theory. In the field, however, the actual response of the soil will be subject to the three-dimensional condition during consolidation. In this research, a new estimation method of the coefficient of consolidation for the various stress-deformation conditions was proposed. The good agreement between the computed dissipation of pore pressure and the measured data confirms the usefulness and the applicability of the proposed method to predict the exact rate of consolidation.

• 한국세라믹학회지
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• 제48권1호
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• pp.52-56
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• 2011

Silicon carbide (SiC) is a candidate material for heat exchangers for VHTR (Very High Temperature Gas Cooled Reactor) due to its refractory nature and high thermal conductivity. This research has focused on demonstration of physical properties and mock-up fabrication for the future heat exchange applications. It was found that the SiC-based components can be applied for process heat exchanger (PHE) and intermediate heat exchanger (IHX), which are operated at $400{\sim}1000^{\circ}C$, based on our examination for the following aspects: optimum fabrication technologies (design, machining and bonding) for compact design, thermal conductivity, corrosion resistance in sulfuric acid environment at high temperature, and simulation results on heat transferring and thermal stress distribution of heat exchanger mock-up.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.881-886
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• 2009

Bio safety level-3 laboratory is the research facility with concerns for the BL-3 contamination, at the same time the safety of it is guarantied. Based on comfortable environmental maintenance of the research laboratory, building, machinery, electricity, and controls are facilitated to keep airtightness(minus pressure) of each room in case of not only access and operation, but even emergency.

• 한국응용과학기술학회지
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• 제20권1호
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• pp.57-63
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• 2003

An intermediate, tetramethylene bis (orthophosphate), was prepared by the esterification of pyrophosphoric acid and l,4-butanediol. Then pyrophosphoric-containing modified polyesters (ATTBs) were synthesized by polycondensation of tetramethylene bis(orthophosphate), trimethylolpropane, adipic acid, and l,4-butanediol. The content of l,4-butanediol was varied from 10 to 20wt% for the reaction. The increase of the amount of l,4-butanediol in the synthesis of ATTBs resulted in increase in average molecular weight and decrease in kinematic viscosity owing to the excellent flowability and reactivity of l,4-butanediol.

• Tribology and Lubricants
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• 제26권3호
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• pp.190-198
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• 2010

GTL(gas-to-liquid) fuel produced by the Fischer-Tropsch process using carbon monoxide(CO) and hydrogen(H2) is expected to be one of the environmental friendly fuel for alternative and blended to petrodiesel. But GTL have poor lubricity due to paraffin as main component of GTL which is not involve polar materials. In this paper, we had investigated the lubricity improvement of GTL fuels with various lubricants using HFRR(high frequency reciprocating rig).