• 한국분말재료학회지
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• 제25권3호
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• pp.251-256
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• 2018

We report the feasibility of TaC production via self-propagating high temperature synthesis, and the influence of the initial green compact density on the final composite particle size. Experiments are carried out from a minimum pressure of 0.3 MPa, the pressure at which the initial green body becomes self-standing, up to 3 MPa, the point at which no further combustion occurs. The green density of the pellets varies from 29.99% to 42.97%, as compared with the theoretical density. The increase in green density decreases the powder size of TaC, and the smallest particle size is observed with 1.5 MPa, at $10.36{\mu}m$. Phase analysis results confirm the presence of the TaC phase only. In the range of 0.3-0.5 MPa, traces of unreacted Ta and C residues are detected. However, results also show the presence of only C residue in the matrix within the pressure range of 0.6-3.0 MPa.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.776-785
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• 2006

Ship builder's requirement for a higher power output rating has lead to the development of super large two stroke low speed diesel engines. Usually a large-sized bore ranging from 8-14 cylinders, this engine group is capable of delivering power output of more than 100,000 bhp at maximum continuous rating. Other positive aspects of this engine type include higher thermal efficiency, reliability, durability and mobility. This all playa vital role in meeting the propulsion requirement of vessels, specifically for large container ships, of which speed is a primary concern to become more competitive. Consequently, this also resulted in the modification of engine parameters and new component designs to meet the consequential higher mean effective pressure and higher maximum combustion pressure. Even though the fundamental excitation mechanism unchanged, torsional vibration stresses in the propulsion shafting are subsequently perceived to be higher. As such, one important viewpoint in the initial engine design is the resulting vibration characteristic expected to prevail on the propulsion shafting system(PSS). This paper investigated the torsional vibration characteristics of these super large engines. For the two node torsional vibration with a nodal point on the crankshaft, a tuning damper is necessary to reduce the torsional stresses on the crankshaft. Hence, the tuning torsional vibration damper design and compatibility to the shafting system was similarly reviewed and analyzed.

• 조명전기설비학회논문지
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• 제23권10호
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• pp.115-120
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• 2009

본 연구에서는 기존 소방시스템의 문제점을 개선한 인공지능형 방향성 유도등 제어 시스템에 적용하기 위해 필요한 최적 피난유도 알고리즘 설계기법을 제시하였다. 인공지능형 방향성 유도등 제어 시스템은 화재 감지기 및 수신반과 연동하여 화재 발생시 발화부 및 연기 이동에 대한 판단을 통하여 최적의 비상대피 유도라인을 계산하여 인명 피해를 최소화하는데 그 목적이 있다. 이러한 최적 피난유도 알고리즘 구현을 위하여 최단거리 계산 알고리즘인 FLOYD 알고리즘을 이용하였으며, 각 지역 감지기의 감지 신호에 대한 위험상태에 따라 지역 위험인자를 적용한 최단거리 산출기법으로 구현하였다.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2001년도 정기총회 특별강연 및 춘계학술연구발표회(2)
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• pp.85-91
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• 2001

This paper provides a case study of landfill gas (LFG) utilization fer direct use as process fuel, and for electrical power generation at restored landfills in the Hong Kong Special Administrative Region of China (HKSAR). The paper specifically covers the LFG utilization schemes, which are required under landfill restoration contracts at the Shuen Wan and Urban Landfills. These contracts provide for the restoration and aftercare of six landfills, and are administered by the Environmental Protection Department (EPD) of the Hong Kong Government. The LFG utilization scheme at the Shuen Wan Landfill incorporates the direct use of LFG by compressing and dehumidifying the LFG prior to conveyance through a 1.6-kilometer (1-mile) pipeline. The pipeline provides an alternate fuel source to naphtha during process heating for gas production at the Tai Po Gas Production Plant of the Hong Kong and China Gas Limited (HKCC). The LFG utilization scheme at the Jordan Valley Landfill (one of the Urban Landfills) beneficially uses the LFG as fuel for electrical power generation with reciprocating internal combustion engines. The LFG is compressed, cooled, and filtered prior to delivery to two engine/generator sets. This system provides power to operate the leachate pre-treatment plant, which processes leachate from all of the Urban Landfill sites. The case study will examine the technical and non-technical considerations, including harriers, for developing, designing and implementing the LFG utilization projects in Hong Kong. Specific regulatory considerations and external governmental agency approvals are discussed, including the requirement to register as a gas-producing utility. While the paper focuses on LFG utilization applications in Hong Kong, many of the considerations discussed are also applicable to development of LFG utilization in other regions of Asia.

• 공업화학
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• 제31권3호
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• pp.284-290
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• 2020

Energetic thermoplastic elastomers (ETPEs) based on glycidyl azide polymer (GAP) and carboxylated GA copolymers [GAP-ETPE and poly(GA-carboxylate)-ETPEs] were synthesized using isophorone diisocyanate (IPDI), dibutyltin dilaurate (DBTDL), 1,4-butanediol (1,4-BD), and soft segment oligomers such as GAP and poly(GA-carboxylate). The synthesized GAP-ETPE and poly(GA-carboxylate)-ETPEs were characterized by Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), universal testing machine (UTM), calorimetry and sensitivity towards friction and impact. DSC and TGA results showed that the introduction of carboxylate group in GAP helped to have better thermal properties. Glass transition temperatures of poly(GA-carboxylate)-ETPEs decreased from -31 ℃ to -33 ℃ compared to that of GAP-ETPE (-29 ℃). The first thermal decomposition temperature in poly(GA_0.8-octanoate_0.2)-ETPE (242 ℃) increased in comparison to that of GAP-ETPE (227 ℃). Furthermore, from calorimetry data, poly(GA-carboxylate)-ETPEs exhibited negative formation enthalpies (-6.94 and -7.21 kJ/g) and higher heats of combustion (46713 and 46587 kJ/mol) compared to that of GAP-ETPE (42,262 kJ/mol). Overall, poly(GA-carboxylate)-ETPEs could be good candidates for a polymeric binder in solid propellant due to better energetic, mechanical and thermal properties in comparison to those of GAP-ETPE. Such properties are beneficial to application and processing of ETPE.

• 한국응용과학기술학회지
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• 제29권1호
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• pp.129-140
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• 2012

우리나라에서 건축물 내장재의 화재안전성능은 국토해양부 고시 제2011-39호에 의한 평가방법에 의해 불연성시험(KS F ISO 1182), 열방출률시험(KS F ISO 5660) 및 가스유해성시험(KSF 2271)을 실시하여 그 결과로서 분류하도록 되어 있다. 그 중 연기 및 연소독성가스에 대한 시험인 가스 유해성 시험은, 건축재료 및 내장재의 연소시 발생하는 가스의 유해성을 마우스의 평균 행동정지시간으로 측정하는 방법으로 사용하여 왔다. 이 중 연소 독성가스 4종(HCl, HF, HCN, $SO_2$) 흡입독성시험방법의 확립을 위하여 ICR계 mouse와 전신흡입노출장치를 이용하여, 독성가스 노출 및 병리검사를 수행하였다. 그 결과 호흡기관지와 가까운 폐포에서 대식세포(Macrophage)의 침윤을 유발하는 것으로 나타났고, 4종의 물질에 대한 조직의 병리검사로 전체적으로 충혈과 울혈은 확인되었다. 조직 중 폐와 신장에서 조직손상이 심하였고, 물질로는 HCN이 가장 많은 병리소견을 보였다.

• 대한기계학회논문집B
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• 제36권8호
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• pp.849-855
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• 2012

대향류 버너에서 질소로 희석시킨 메탄 연료의 확산화염에 대하여 AC 전기장을 인가하여 전압크기 및 주파수 변화에 의한 영향을 실험적으로 조사하였다. 그 결과, 임계주파수를 초과하는 AC 주파수 영역에서 안정한 확산화염이 나타났으며, 인가된 AC 전압크기의 증가에 따라 그 임계주파수는 증가하다가 약 35Hz 로 일정한 값을 보였다. 반면에, 임계주파수 미만의 AC 주파수 영역에서, 그 확산화염은 인가된 AC 주파수에 동기되어 진동하였다. 화염지역 내에 양이온들은 로렌츠 힘에 의하여 가속되고, 그 양이온과 중성자 간의 분자단위의 충돌에 의한 운동량의 전달에 의해 전체적인 유동장의 변화가 발생하는데, 이러한 이온풍의 효과에 의하여 화염의 진동 현상이 나타날 수 있다.

• 한국재료학회지
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• 제28권1호
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• pp.6-11
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• 2018

There are various manufacturing processes for pure $SiO_2$ that is used as abrasives, chemicals, filters, and glasses, and in metallurgy and optical industries. In the optical fiber industry, to produce $SiO_2$ preform, $SiCl_4$ is utilized as a raw material. However, the combustion reaction of $SiCl_4$ has caused critical environmental issues, such as ozone deficiency by chlorine compounds, the greenhouse effect by carbon dioxide and corrosive gas such as hydrochloric acid. Thus, finding an alternative source that does not have those environmental issues is important for the future. Octamethylcyclotetrasiloxane (OMCTS or D4) as a chlorine free source is recently promising candidate for the $SiO_2$ preform formation. In this study, we first conducted a vaporizer design to vaporize the OMCTS. The vaporizer for the OMCTS vaporization was produced on the basis of the results of the vaporizer design. The size of the primary particle of the $SiO_2$ formed by OMCTS was less than 100 nm. X-ray diffraction patterns of the $SiO_2$ indicated an amorphous phase. Fourier-transform infrared spectroscopy analysis revealed the Si-O-Si bond without the -OH group.

• 한국자동차공학회논문집
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• 제16권6호
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• pp.104-108
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• 2008

Recently, studies conducted by our research group, revealed the possibility for reducing BSFC, NOx and PM emissions to meet the Euro 4 & 5 legislations. The main objective of the present study is to get better fuel economy in commercial vehicles by considering real driving conditions. Firstly, in order to improve fuel economy on fields, specifically it is required to analyze the driving pattern and make the representative modes from real field data. Secondly, it is performed to make the engine dynometer test to optimize the fuel consumption by reflecting on the representative driving modes, based on the Korea 2008 emission legislation equal to the Euro 4. The engine components such as engine calibration, combustion chamber, turbocharger and ancilliaries were modified to optimize vehicle fuel economy over a typical customer drive cycle whilst still meeting the exhaust emission restrictions. Finally, these results were confirmed by field testing of vehicle equipped with the updated calibration engine. It was placed the two vehicles together traveling the same route and accomplishing the same amount of stops(back to back), in order to evaluate the fuel consumption in comparison to the current vehicle. Through several repeats such as the engine calibration and field test, we could get 3 % to 7.7 % vehicle fuel economy improvements compared to previous vehicle.

• 한국수소및신에너지학회논문집
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• 제18권1호
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• pp.46-51
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• 2007

LSM powder material for an oxygen-electrode(anode) of High Temperature Steam Electrolysis (RISE) was synthesized by a Modified-Glycine nitrate process(GNP). Amount of nitric acid and its concentration was varied to find out an appropriate composition for the oxygen-electrode(anode). In order to optimize the amount of Glycine used as an oxidant of self-combustion process, the ratio of Glycine to Anion was varied. $La_{0.8}Sr_{0.2}MnO_3$, $La_{0.5}Sr_{0.5}MnO_3$, and $La_{0.2}Sr_{0.8}MnO_3$ were synthesized in this study. Those LSM were dried for overnight to remove moisture from the material at $110^{\circ}C$ and were calcined 2 hours at $650^{\circ}C$ and were sintered in a furnace for 5 hours at $1400^{\circ}C$. Their structures, surface morphologies, surface areas, and weight changes were investigated with XRD, SEM, BET, and TG/DTA. The best perovskite phase for the oxygen-electrode of HTSE was obtained with $La_{0.8}Sr_{0.2}MnO_3$ formula in which 100 ml of 3M nitric acid was used in the preparation of its formula. The optimized ratio of Glycine to Anion was 2.