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김동희,유재근,Kim, Donghee,Yu, Jaekeun The Korean Institute of Resources Recycling 2018 資源 리싸이클링 Vol.27 No.2
In this study, waste ITO target is dissolved into hydrochloric acid to generate a complex indium-tin chloride solution. Nano sized ITO powder with an average particle size below 30 nm are generated from these raw material solutions by spray pyrolysis process. Also, in this study, thermodynamic equations for the formation of indium-tin oxide (ITO) are established. As the reaction temperature increased from $800^{\circ}C$ to $900^{\circ}C$, the proportion and size of the spherical droplet shape in which nano sized particles aggregated gradually decreased, and the surface structure gradually became densified. When the reaction temperature was $800^{\circ}C$, the average particle size of the generated powder was about 20 nm, and no significant sintering was observed. At a reaction temperature of $900^{\circ}C$, the split of the droplet was more severe than at $800^{\circ}C$, and the rate of maintenance of the initial atomized droplet shape decreased sharply. The average particle size of the powder formed was about 25 nm. The ITO particles were composed of single solid crystals, regardless of reaction temperature. XRD analysis showed that only the ITO phase was formed. Remarkably, the specific surface area decreased by about 30% as the reaction temperature increased from $800^{\circ}C$ to $900^{\circ}C$.
김동희,유재근,Kim, Donghee,Yu, Jaekeun The Korean Institute of Resources Recycling 2018 資源 리싸이클링 Vol.27 No.2
This study was conducted as a preliminary study for the recycling of palladium and palladium oxide. In this study, thermodynamic equations for the formation of palladium oxide (PdO) are established. Palladium chloride is dissolved into hydrochloric acid to generate a palladium chloride solution. Nanosized palladium oxide powder with an average particle size below 30 nm were generated from this raw material solution by means of a spray pyrolysis process. The palladium oxide particles were composed of a single solid crystal. The results of XRD analysis showed that only a PdO phase of the generated powder was formed. And, the specific surface area of the generated palladium powder was approximately $32m^2/g$.
단기통엔진에서의 GTL(Gas-To-Liquid) 연료특성 연구
김동희(Donghee Kim),이용규(Kyungok Cha),최교남(Yonggyu Lee),정동수(Kyonam Choi),차경옥(Dongsoo Jeong) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Recently, alternative fuels are drawing more attentions due to the increasing need for lower emission characteristics and fuel consumption rate in automotive engine. The GTL(gas to luquid) is the one of most favored candidates. GTL is a synthetic liquified fuel made from natural gas or charcoal with Fischer-Tropsch mechanism. It has higher cetane number(more than 75) and almost negligible sulphur and aromatic contents. Therefore, enhanced emission characteristics are expected even in the application in diesel engines without any modification. In this study, the engine performances and emission characteristics are compared between diesel and GTL fuel in the single cylinder diesel engine. Also the various blendings between Diesel and GTL(30%, 50% in volume) are also tested to investigate optimal blending ratio in the respect of emission characteristics. Noticeable reduction in soot, THC and CO emission are observed without the loss of engine power due to low sulphur and aromatic contents in GTL. Also, the ignition delay decreased due to higher cetane number of GTL, which slightly decreased the amount of NOx emissions.
산소 부화 조건의 메탄 무화염 연소에 관한 실험적 연구
김동희(Donghee Kim),허강열(Kang Y. Huh),이영재(Youngjae Lee) 한국연소학회 2020 한국연소학회지 Vol.25 No.3
This study was conducted to analyze the characteristics of flameless combustion and emissions using the lab-scale flameless combustion system fueled with methane. Especially, experiments were performed under oxygen-enriched conditions to expand the applications of flameless combustion and NOx reduction. The combustor able to induce the internal flue gas recirculation was applied, while the preheating of fuel and oxidant was not considered. The fraction of oxygen in oxidant was varied from 24.4% to 26.3%. The heat input was fixed at 3 kWth in all cases. From the experimental results, there was three combustion modes as the conventional flame, transitional period and flameless combustion. In the transitional period, the ignition and extinction of flame occurred repeatedly. Also, the flue gas compositions and pressure of the combustor were unstable. In the flameless combustion, the hot-spot of the conventional flame disappeared and the temperature distribution of the combustor became uniform. Moreover, the thermal-NOx was reduced in the flameless combustion mode and the trade-off relationship between CO and NOx was improved.
이동질량장치와 부력엔진을 포함한 무인 수중글라이더의 동역학 모델링 및 운동성능 해석
김동희(Donghee Kim),이상섭(Sang Seob Lee),최형식(Hyeung Sik Choi),김준영(Joon Young Kim),이신제(Shinje Lee),이용국(Yong Kuk Lee) 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.5
Underwater gliders do not have any external propulsion systems that can generate and control their motion. Generally, underwater gliders would obtain a propulsive force through the lift force generated on the body by a fluid. Underwater gliders should be equipped with mechanisms that can induce heave and pitch motions. In this study, an inner movable and rotatable mass mechanism was proposed to generate the pitch and roll motions of an underwater glider. In addition, a buoyancy control unit was presented to adjust the displacement of the underwater glider. The buoyancy control unit could generate the heave motion of the underwater glider. In order to analyze the underwater dynamic behavior of this system, nonlinear 6-DOF dynamic equations that included mathematical models of the inner movable mass and buoyancy control unit were derived. Only kinematic characteristics such as the location of the inner movable mass and the piston position of the buoyancy control unit were considered because the velocities of these systems are very slow. The effectiveness of the proposed dynamic modeling was verified through sawtooth and spiraling motion simulations.