• 한국수소및신에너지학회논문집
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• 제21권2호
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• pp.123-128
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• 2010

Hydriding combustion synthesis (HCS) can produce full hydrides of alloys and in a short time. The conventional process based on ingot metallurgy cannot produce Mg-based alloy easily with the desired composition and the cast product needs a ling activation process for the practical use of hydrogen storage. In this study, the hydriding properties of Mg-xNi (x=5, 13.5, 54.7wt.%) alloys prepared by hydriding combustion synthesis were evaluated. The hydrogen storage capacity and kinetics of HCS Mg-xNi alloys were strongly dependent on the content of Ni. The HCS Mg-13.5wt.%Ni alloy shows the hydriding behavior to reach the maximum capacity within 30 min. and the reversible $H_2$ storage of 5.3wt.% at 623 K.

• 한국세라믹학회지
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• 제44권3호
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• pp.152-156
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• 2007

Tungsten carbide powder was synthesized by SHS (self-propagating high-temperature synthesis). Except $WO_{3}$, each concentration of raw material ($WO_{3},\;Mg,\;NaCl,\;Na_{2}CO_{3},\;C$) was investigated. Final product was characterized by XRD and SEM. X-ray data demonstrated that the $NaCl+Na_{2}CO_{3}$ combined mixture has superiority in the WC formation process. Single phase and submicrometer WC powder was synthesized at the temperature below $1600^{\circ}C$. The role of sodium salts in combustion process was discussed, and chemical mechanism of WC formation was proposed. WC powder prepared by salt-assisted combustion synthesis has a size $0.2{\sim}3\;{\mu}m$ and low agglomeration degree.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 춘계학술대회 논문집
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• pp.209-217
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• 1994

The present study is concerned with the characteristics of the high speed precision bar cropping. This process is a practical application of High Energy Rate Forming in which the impact energy source is given by internal combustion engine. To enhance the added value of product, the recent forging fields trend toward the near net shape processes through the cold and closed die forging. For the purpose of these processes the precedent process is to obtain the precision billet which has little weight deviation and defect. The accuracy of initial billet by bar cropping depends upon the process parameters and die design technology. Therefore, in order to investigate the effect of process parameters upon product quality, the cropping experiments are carried out according to the various parameters such as billet clearence, billet length, billet material, cropping speed and so on. From these results some criteria of the optimal die design for the product of good quality are suggested.

• 한국세라믹학회지
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• 제31권3호
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• pp.265-274
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• 1994

Intermetallic Ti-Si system ceramics were synthesized from stochiometric mixtures of titanium and silicone powders in vacuum by Self-propagating High-temperature Synthesis(SHS). In each cases of Ti5Si3, Ti5Si4 and TiSi, and TiSi2 synthesis, 20wt% product dilution, direct ignition and SHS chemical furnace method were employed. The combustion modes, which were observed during the synthesis process by using the high speed camera, of Ti5Si3, Ti5Si4, TiSi, and TiSi2 exhibit spin, osciallatory, steady-state, and spin combustion, respectively. With increasing Ti/Si molar ratio an decrease of combustion velocities was found. From the results on the measurement of the flexural strength, the specimen hot pressed at 135$0^{\circ}C$ for 30 min using synthesized Ti5Si4 powders showed the highest flexural strength at 215 MPa.

• 한국세라믹학회지
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• 제27권1호
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• pp.118-126
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• 1990

Titanium Cabride powders were prepared by the self-propagating high temperature synthesismethod in air from the mixture of metal titanium powder and carbon powder. The result are as follows : 1. The conversion effciency of higher than 95% can be obtained and the lattice constant value of the product was 4.322$\AA$. 2. The combustion mode, velocity and temperature of combustion wave was photographed using high-speed camera, and showed steady-state, velocity of 15.414mm/sec at 250$0^{\circ}C$. 3. The relative density and MOR strength of TiC sintered at 180$0^{\circ}C$ for 90 minutes by hot-pressing under the pressure of 200kg/$\textrm{cm}^2$ were 95% and 395MPa, respectively.

• 한국대기환경학회지
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• 제12권5호
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• pp.577-585
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• 1996

A screening study was performed in order to resolve the flow, combustion and emission characteristics of the gas furmace with co-axial diffusion flane burner. A control-valume based finite-difference method with the power-law scheme was employed for discretization. Numerical procedure for the differential equation was used by SIMPLEST to enclosute rapid converge. A k-.varepsilon. model was incorporated for the closure of turbulence. The mass fraction and mixture fraction were calculated by cinserved scalar method. An equilibrium analysis was employed to determine the concentration of radicals in the product stream and conserbation equations were them solved for N amd NO by Zelovich reaction scheme. The method was exercised in a simple one-dimensional case first, to determine the effects of air ratio, temperature and residence time on NO formation and applied to a furnace with co-axial diffusion flame burner.

• 소음진동
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• 제7권4호
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• pp.689-700
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• 1997

There are many difficulties in designing the engine structure properly due to the strong conflicts between NVH characteristics and the high performance, light weight and low product cost. Many feasible noise reduction techniques should be carefully incorporated to meet such stringent noise requirements. It is also required that the engine development be carried out by introducing concurrent engineering, in which the analysis and test database are usefully applied to the detail designs from the 1st stage. This paper reviews the significance of the noise characteristics of the structure elements in relation to the combustion pressure. The mechanisms of the crank shaft rumbling, which is the main source having the bad influence on the sound quality, are also explained. The influences of dynamic behavior of engine structure on its noise are investigated, followed by discussions on experimental results of the features necessary for the design of low noise engine concepts.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
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• pp.35-41
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• 2001

A second-order conditional moment closure(CMC) model is applied to the prediction of local extinction in a turbulent hydrocarbon diffusion flame and compared with direct numerical simulation(DNS) results for the flame. Combustion of a hydrocarbon fuel is described by a simple two-step mechanism. A second-order correction for conditional mean reaction rate terms is made by the assumed pdf method. The results show that the second-order closure is necessary for accurate prediction of intermediate species, while first-order CMC gives good predictions for fuel, oxidant, product and temperature. Conditional variances and covariances are well predicted during an extinction process while they are overpredicted during a reignition process.

• 대한기계학회논문집B
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• 제35권5호
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• pp.539-545
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• 2011

맥동연소기술을 적용한 산업용 복사관버너의 연소특성을 살펴보기 위해 실규모 (120,000 kcal/h) 산업용 복사관버너 설비를 사용하여 실험실 및 현장 테스트를 수행하였다. 제철부생가스를 사용하는 산업용 복사관버너의 3 가지 종류를 하나의 W 형 복사관이 장착된 실험설비에서 실험하였다. W 형 복사관이 다수 사용되는 대형 설비를 이용하여 장기운영 실험을 실시하였다. 맥동연소기술을 적용한 기실험설비들을 대상으로 성능향상 및 배가스조절 측면에서 다양한 실험조건으로 테스트를 진행 하였다. 맥동연소기술의 적용가능성 평가를 위해 NOx 저감 및 효율향상을 분석하였다. 맥동연소기술의 적용결과 에너지 절감, 복사관 수명 향상 및 생산성 향상 등이 얻어짐을 확인할 수 있었다. 최고의 성능 및 배가스 조절을 얻기 위한 최적의 운전조건이 각 버너별로 결정되었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.782-783
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• 2006

Titinium carbide $(TiC_x)$ was produced by self-propagating high temperature synthesis (SHS) method. The morphology and non-stoichiometric number of the SHS product were observed by scanning electron microscopy and neutron diffractometry, respectively. Tubular titanium carbide with hole inside was formed with different non-stoichiometric number (x), which value increased with combustion temperature.