• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.536-540
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• 2018

As the performance of engines improves, the temperature of engines is increasing, resulting in a high piston temperature. An excessively high piston temperature may result in torque drop or engine failure. An oil jet is used to reduce the piston temperature. In this study, to monitor the effect of oil jet, a templug was used to measure the piston temperature. A templug is a kind of sensor and the hardness of the templug changes according to the piston temperature. Using a templug, the maximum temperature of the piston was measured with and without an oil jet. The piston temperature was lowered using the oil jet. The highest temperature region changed from the center crown to the front/rear area. In addition, the temperature difference between the highest and lowest regions became smaller.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1520-1522
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• 1999

저 전압용 형광체는 최근에 활발히 연구가 진행되고 있으며 가장 대표적인 형광체가 ZnO : Zn 녹색 형광체이다. ZnO : Zn 형광체는 자체발광형 형광체로써 ZnO을 환원분위기 하에서 열처리를 함으로써 얻을 수 있다. 본 연구에서는 자발착화 연소반응법(Glycine Nitrate Process)을 이용하여 ZnO : Zn 분말을 합성하고 형광특성 및 분말특성을 알아보았다. 출발물질로는 Zn Nitrate와 Glycine을 이용하였고 자발연소 반응이 발생하는데 적절한 글리신의 양을 확인하기 위해서 글리신과 양이온의 비를 변화시키며 ZnO를 합성하였다. 그리고 Zn Excess가 생겨난 양과 그에 따른 형광특성을 관찰하기 위해 $N_2$ 분위기에서 각기 $500^{\circ}C,\;750^{\circ}C,\;950^{\circ}C$의 온도에서 열처리를 행하였다. 제조된 ZnO 분말의 입자형태와 결정상태는 SEM과 XRD를 이용하여 분석하였고 TG-DTA를 측정하여 열처리 온도에 따른 질량감소(ZR excess)를 관찰하였다. 또 Particle size analyzer로 분말의 크기를 알아보았고 형광체로써의 발광특성을 살펴보기 위해 PL을 이용하여 발광피크를 관찰하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.84-90
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• 2016

Various form of membrane structures are being built in recent years. However, there is no appropriate fire proofing standards which can be applied each specific membrane structures. Therefore, existing fire protection standards are in establishment state and they need to be revised. In the current study, commonly used membrane materials(ETFE, PVF, PTFE) has been selected to investigate its fire resistance behavior with the change of fire duration time. In addition to this, heat generation rate of the membrane materials in correlation with the height of membrane has been investigated. And these fire combustion characteristics of membrane materials can be used in future practice for the fire prevention regulations of membrane structures.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.113-113
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• 2014

This study has been conducted for evaluation of qualitative/quantitative risk of HCNG filling station. In case of fire explosion occurred because of hydrogen, CNG, and HCNG leaking on same conditions, maximum overpressure was measured as 30kPa for hydrogen, 3.5kPa for HCNG, and 0.4kPa for CNG. The overpressure of HCNG was measured 7.75 times higher than that of CNG, but it was only 11.7% compared with hydrogen. When the explosion was occurred, in case of hydrogen, the measured influential distance of overpressure was 59m and radiant heat was 75m. In case of CNG, influential distance of overpressure was 89m and radiant heat was 144m would be estimated. In case of 30% HCNG that was blended with hydrogen and CNG, influential distance of overpressure was 81m and radiant heat was 130m were measured. As the explosion occurred with the same sized container that had 350bar for hydrogen and 250bar of CNG and HCNG, the damage distance that explosive overpressure and radiant heat influenced CNG was seen as the highest. HCNG that was placed between CNG and hydrogen tended to be seen as more similar with CNG.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.573-580
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• 1998

Self-propagating high temperature synthesis (SHS) technique was used to synthesize the spinel phase of $MgAl_2O_4$ from MgO and Al powder. Thermit reaction products of MgO and Al, The reaction products were heat treated at the temperature $800^{\circ}C$ preheating. Processing factors such as DTA/TG, combustium product and maxium temperature, synthesis of MgO and Al from "$MgO+2Al+3/2O_2$\rightarrow$MgAl_2O_4$". An activation energy (${\Delta}H^{\circ}$)-264.8 kcal/mol and reaction of maxium temperature 5634 K was calculated to form a $MgAl_2O_4$ spinel from unreacted materials. Pellet were increased volume 6% after thermit reaction. reaction.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.160-165
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• 2002

The heavy-duty LPG-fueled single cylinder engine was designed and developed as a fundamental equipment for analyzing combustion processes and emission performances. The cylinder head and the piston crown were modified to fire the LPG in the engine. The flywheel was also fabricated to minimize the vibration of the single cylinder engine. The size of bore and stroke of the tested engine are 130 mm and 140 mm, respectively. Compression ratios were varied 8 to 9 with different piston crown shapes. The developed single cylinder engine operates at 1,000 rpm for this work. The major conclusions of this work are; (1) the power of the developed engine was peaked at the condition of equivalence ratio 1.0 at three different compression ratios; (2) the power is slightly increased with the increase of compression ratio; (3) the optimum ignition timing is retarded with the increase of compression ratio ranged 2 to 10 crank angle.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.77-82
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• 2000

Numerical simulations of freely propagating flames burning stoichiometric $CH_4$/$O_2$/$N_2$ mixtures are performed at atmospheric pressure in order to understand the effect of the $O_2$ enrichment level on $CH_4$/Air flame. A chemical kinetic mechanism is employed, the adopted scheme involving 54 gas-phase species and 632 forward reactions. The calculated flame. speeds are compared with the experiments for the flames established at several $O_2$ enrichment level, the results of which is in excellent agreement. As a result of the increased $O_2$ enrichment level from 0.21 to 1, the mole fraction of CO in the burned gas is increased. The flame speed and the temperature in the burned gas are also increased, but the thickness of the flame is severely shrunken in the preheat region.

• Journal of the Korean Society of Combustion
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• v.15 no.3
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• pp.48-56
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• 2010

Performances of power generation engine were investigated with syngas from RPF. A stoker type, multi-staged pyrolysis-gasification system, was employed for syngas generation and the syngas was refined with the sequential cleaning processes composed of a gas cooler, a bag filter and a wet scrubber. 20 kWe commercial syngas power generation engine was adopted to burn the cleaned syngas which is mainly composed of hydrogen, carbon monoxide, carbon dioxide and methane. The performance of the engine was tested with various syngas compositions and the results were compared to LNG case. Electric power output, exhaust gas temperature, and emission characteristics were measured, and the efficiency of engine generation was investigated as a function of load of power generation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.542-545
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• 2009

In this study, the effect of turbine geometry on the overall performance of a gas turbine was investigated by computational fluid dynamics. Overall engine performance was predicted through a full engine simulation program which can predict the interactions of the compressor, the combustor and the turbine. The compressor and the turbine analysis code solves 2D and 3D Navier-Stokes equations respectively. The chemical equilibrium code was applied to simulate the combustor. The computations were performed for two different shapes of turbine nozzle. The nozzle shapes adopted a baseline blade and a blade with fillet.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.2
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• pp.26-31
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• 2017

Environmental problem of the solid propellants is an issue of growing importance in solid rocket. For examples, ammonium perchlorate (AP) as an solid propellants oxidizer could create a poisonous gas and atmospheric pollutions, such as HCl. Among the several oxidizers, N-guanylurea dinitramide (GuDN) is an effective candidate substance for eco-friendly oxidizer, which has high performance, pressure exponent, and eco-friendly smog during combustion for solid propellant of gas generator. In this paper, the theoretical analysis of characteristics as a gas generator propellant, propellant manufacturing processability, propellant hardness properties and combustion characteristics were studied.