• Transactions of the Korean hydrogen and new energy society
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• v.21 no.3
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• pp.149-157
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• 2010

The electromagnetic characteristics of FCEVs (fuel cell electric vehicles) are much different from the existing combustion engine cars as well as hybrid, plug-in-hybrid, and pure electric vehicles due to the high voltage/current generated by a fuel cell stack which uses a compressed hydrogen gas reacted with oxygen. To operate fuel cell stack efficiently, BOP (Balance of Plant) is essential. BOP systems are used many not only for motors in water pump, air blower, and hydrogen recycling pump but also inverters for these motors. Since these systems or components are connected by high voltage cables, EMC (Electromagnetic compatibility) analysis for high voltage/current cable is the most important element to prevent the possible electric functional safety errors. In this paper, electromagnetic fields of high current/voltage cable for FCEVs is studied. From numerical analysis results, time harmonic magnetic field strength of high current/voltage cable have difference of 20～28 dB according to phase. EMI result considered ground effect of FECV at 10 m shows difference of 14.5 dB at 30 MHz and 2.8 dB at 230 MHz compared with general cable.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.3
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• pp.1050-1060
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• 1996

Recently, attention has been paid to the flame diagnostic by noncontact methods which dose not deform the flame shape. One of them is a method which is using the radical luminous intensity. Generally, this diagnostic method using radical luminous has been investigated its reliability by applying to laminar flame. This study, however, investigated each radical luminous signals through stocastical analysis like auto-correlation, cross-correlation, phase and coherence which were acquired from measuring radical luminous intensity of OH, CH, $O_{2}$, radicals in turbulent diffusion flame. To compare radical luminous intensity in flame with temperature, ion current and concentration , radious distribution of each properties was investigated and considered. In radical luminous intensity, correlation in the reaction zone of flame was higher than in correlation in combusted gas zone. And radious distribution of radical luminous intensity was corresponded with radious distribution of temperature, ion current and concentration. The result of the study confirms that a radical luminous flame diagnosis is possible in the turbulent diffusion flame.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.89-96
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• 2016

The mechanism for laminar dust flame propagation can only be elucidated from a comprehensive mathematical model which incorporates conduction and radiation, as well as the chemical kinetics of particle devolatilization and gas phase and char reaction. The mathematical model for a flat, laminar, premixed coal-air flame is applied to the atmospheric coal-air mixtures studied by Smoot and co-workers, and comparisons are made with their measurements and predictions. Here the principal parameter for comparison is the laminar burning velocity. The studies of Smoot and co-workers are first reviewed and compared with those predicted by the present model. The effects of inlet temperature and devolatilization rate constants on the burning velocities are studied with the present model, and compared with their measurements and predictions. Their measured burning velocities are approximately predicted with the present model at relatively high coal concentrations, with a somewhat increased inlet temperature. From the comparisons, their model might over-estimate particle temperature and rates of devolatilization. This would enable coal-air mixtures to be burned without any form of preheat and would tend to increase their computed values of burning velocity.

• Journal of Ceramic Processing Research
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• v.20 no.3
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• pp.222-230
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• 2019

Microwave hydrothermal-assisted sol-gel method was employed to synthesize the Fe doped TiO2 photocatalyst. The morphological analysis suggests anatase phase nanoparticles of ~20 nm with an SBET area of 283.99 ㎡/g. The doping of Fe ions in TiO2 created oxygen vacancies and Ti3+ species as revealed through the XPS analysis. The reduction of the band gap (3.1 to 2.8 eV) is occurred by doping effect. The as-prepared photocatalyst was applied for removal of NOx under solar light irradiation. The doping of Fe in TiO2 facilitates 75 % of NOx oxidation efficiency which is more than two-fold enhancement than the TiO2 photocatalyst. The possible reason of enhancement is associated with high surface area, oxygen vacancy, and reduction of the band gap. Also, the low production of toxic intermediates, NO2 gas, is further confirmed by Combustion Ion Chromatography. The mechanism related NOx oxidation by the doped photocatalyst is explained in this study.

• Textile Coloration and Finishing
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• v.33 no.4
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• pp.230-237
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• 2021

The flame-retardant (FR) treatments of wool fibers using Hexafluorozirconate/titanate salts and tetrabromophthalic anhydride can cause skin irritation and gas toxicity due to Zr and Br compounds respectively. A water-soluble polyfunctional cyclophosphazene derivative, synthesized through substitution reaction of Hexachloro cyclophosphazene and N-[3-(Dimethylamino)propyl] metacrylamide, was applied as a durable flame-retardant for wool fabrics. Also, a crosslinked structure was introduced to improve washing durability of the FR-wool, up to 10 laundering cycles, using Acrylamide(AAm) and Triacryloylhexahydrotriazine (TAHT) as a comonomer and a crosslinker respectively. The mole ratios of the TAHT and AAm concentrations compared to the Dichloro tetrakis{N-[3-(Dimethylamino)propyl]methacrylamido} cyclcophosphazene (DCTDCP) were optimized to 1.33 and 7.5 respectively. In addition, the pyrolysis and combustion properties of the FR wool were assessed using LOI, TGA and microcalorimetry suggesting a solid-phase FR mechanism.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.154.1-154.1
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• 2010

석탄가스화복합발전(IGCC)에서는 석탄을 가스화하여 얻어진 합성가스로부터 이산화탄소를 분리/회수하고 수소는 유용하게 사용할 수 있다. 이 기술의 핵심은 $H_2+CO_2$ (40%) 합성가스로부터 $CO_2$를 경제적이고 효과적으로 분리/회수하는 것이다. 본 연구에서는 합성가스로부터 $CO_2$를 효과적으로 분리/회수하기 위해 가스 하이드레이트 형성법을 제안하였다. 하이드레이트 형성 조건을 완화시켜 주기 위하여 열역학적 촉진제로서 TBAB, TBAF, THF를 첨가하여 열역학적 촉진 현상을 살펴보았다. 다양한 농도의 TBAB (10, 40, 60 wt%), TBAF (10, 34, 45 wt%), THF (4, 19, 31 wt%)에 대하여 3상 평형 (하이드레이트 (H) - 물 (LW) - 기상 (V))을 측정한 결과 40 wt%의 TBAB, 34 wt%의 TBAF, 19 wt%의 THF의 농도에서 가장 큰 촉진효과를 보였으며, 그 이상의 조성에서는 오히려 촉진효과가 줄어드는 것을 확인할 수 있었다. 순수계와 촉진제 첨가계에 대하여 하이드레이트 생성 후의 기상과 하이드레이트상의 $CO_2$ 조성을 측정하였다. 그 결과 모든 실험조건에서 하이드레이트상에 85% 이상의 높은 농도로 $CO_2$가 농축되는 것을 확인하였다. 이러한 과정을 반복하면 순도 99% 이상의 매우 높은 $CO_2$ 기체를 얻을 수 있다. 또한, 가스 하이드레이트 형성과정의 반응특성을 살펴보기 위하여 반응시간에 따른 기상의 $CO_2$ 농도변화를 측정하였다. 본 실험에서 얻어진 결과는 가스 하이드레이트 형성법을 이용한 합성가스 분리 공정 개발에 중요한 기초자료가 될 것으로 사료된다.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.1
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• pp.29-36
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• 2008

Spray characteristics for APU gas turbine engine are investigated. In the test, four flight conditions such as sea level idle, sea level max power, 20,000 feet idle, 20,000 feet max power are used as spray experimental conditions. Spray visualization was performed by using ND-YAG laser bean PDPA(Phase Doppler Particle Analyzer) was used for measuring the particle diameter and velocity from 20 mm to 100 mm from discharge orifice. From the test result, SMD is $90{\sim}95\;{\mu}m$ 맛 20,000 ft idle condition and SMD is $60{\sim}75\;{\mu}m$ at sea level idle condition. Also SMD is $55{\sim}65\;{\mu}m$ at 20,000 ft max power condition and SMD is $30{\sim}70\;{\mu}m$ at sea level max power condition. In the case of 20,000 ft idle condition, combustion instability could be occurred due to the higher drop diameter. Therefore it is necessary to decrease the droplet diameter in the high altitude condition.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.1
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• pp.114-120
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• 2016

This paper describes generating efficiency characteristics of the double acting Stirling engine/generator for domestic small-scale CHP (Combined Heat and Power) system. In small distributed generation applications, Stirling engine has competition from fuel cell, microturbine and etc. In order to be economical in the applications, a long life with minimum maintenance is generally required. Free piston Stirling engine (FPSE) has no crank and rotating parts to generate lateral forces and require lubrication. Double acting Stirling engine/generator has one displacer and two power piston which are supported by flexure springs. Two power pistons oscillate with symmetric displacement and are connected with moving magnet type linear generators for power generation from PV work. In experiments, 1 kW class double acting free piston Stirling engine/generator is fabricated and tested. Heat is supplied to hot end of engine by the combustion of natural gas and converted to electric power by linear generators which are assembled with power pistons. The electric parameters such as voltage, current and phase are measured with for variable flow rate of fuel gas. Especially, generating efficiency of FPSE is measured with three different measurement methods. Generating efficiency of the double acting Stirling engine/alternator is about 24%.

• Journal of the Korean Society of Systems Engineering
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• v.9 no.2
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• pp.23-36
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• 2013

Plant industry is one of technology-intensive and most prosperous industries in Korea because of its recent prosperity and promising outlook in export. However, no Korean EPC company has yet been well prepared in lifting their capacity sufficient enough to get the upstream conceptual or basic design and engineering orders for sizable plant projects which are known as the more value-added. If systems engineering, a methodology which developed complex systems such as airplanes and has been justified its effectiveness in Defense and NASA projects, can be integrated with plant engineering which should be developed and applied based on the requirements of so many stakeholders, conditions, lifecycle concepts, and constraints of the projects, huge synergic effect is expected particularly in developing a specific upstream design, which is a conceptual or basic design. The notion of integration with each other between systems engineering and plant engineering can be really the crux of EPC's success in any plant projects. This paper suggests an approach showing a methodology how to dig out, analyze, evaluate, verify and implement the stakeholders' requirements into a plant design in conceptual phase using the theory and skills of systems engineering. ISO/IEC 15288 well known systems engineering standards is used. Carbon capture system is used for a case study, for it is an emerging technology in reducing emissions of carbon dioxide causing global warming from flue gas after combustion. Here systems engineering was proven to play a substantial role in enhancing the capability of designers in developing a conceptual design of whole plant or certain part of crucial plant systems.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.10-11
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• 1997

고체 추진제를 사용하는 추진 시스템을 개발하는데 가장 커다란 문제로 인식되고 있는 것은 추진제의 연소 특성을 이해하는 일이다. 그 중에서도 연소실의 압력 진동과 추진제 벽면으로 흡수되는 복사 열전달에 의한 연소율(burning rate)의 변화로 인하여 발생하는 연소 불안정에 대한 이해는 아직도 완전히 규명되지 않고 있다. 고체 추진제의 연소 불안정에 대한 이론적 해석은 준-정상 1차원 해석(Quasi-Steady Homogeneous One-Dimension) 방법에 의하여 단순화된 지배방정식을 해석하는 것이 일반적으로 잘 알려져 있는 방법이다. 이 가정은 고체 추진제가 연수되는 영역을 두께가 매우 얇은 영역의 표면반응영역(surface reaction layer)과 화학반응이 없는 응축상태영역(condensed phase zone) 그리고 기체상태의 연료와 화염이 존재하는 기체상태영역(gas phase zone) 등의 3영역으로 구분하며, 기체상태영역에서 발생하는 교란에 대한 응축상태영역의 반응시간 크기(response time scale)가 매우 크기 때문에 응축상태영역의 반응은 준 정상적으로 일어난다고 가정하는 것이다.그러나, 연소실의 온도가 $3000^{\circ}K$ 정도의 높은 온도이어서 복사 열전달에 의한 고체 추진제의 가열이 중요한 열전달 방법으로 작용하게 되므로 이를 무시한 이론적 해석은 물리적인 중요성이 약하여질 수밖에 없다. 본 연구에서는 기체영역으로부터 전달되는 복사 열전달은 투명(transparent)한 표면반응영역을 통과하여 응축상태영역에서 모두 흡수되며 추진제 표면에서의 복사열방출(emission)을 고려하였다. 또한 연소불안정 현상을 해석하기 위하여 표면반응영역에서의 경계조건은 선형교란량으로 대치하는 Zn(Zeldovich-Novozhilov) 방법을 사용하였다. 이 방법은 기체상태영역에 대한 구체적인 해석없이도 연소불안정 현상을 해석할 수 있는 장점이 잇다. 즉 응축상태영역에서의 연소율과 표면온도는 각각 기체영역으로부터 전달되는 온도구배와 연소압력, 그리고 복사 열전달의 함수관계이므로 선형교란에 의한 추진제표면에서의 교란경계조건을 얻을 수 잇으며, 응축영역의 교란지배방정식과 함께 사용하여 압력교란과 복사 열전달의 교란에 대한 연소율의 교란 증감 여부를 판단하여 연소 불안정 현상을 해석할 수 있다.