• 마이크로전자및패키징학회지
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• 제8권1호
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• pp.39-43
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• 2001

$SiC_{x}N$_{y}$ film is deposited by electron cyclotron resonance plasma chemical vapor deposition system using $SiH_4$(5% in Ar), $CH_4$ and $N_2$. Ternary phase $SiC_{x}N$_{y}$ thin film deposited at the microwave power of 600 W and substrate temperature of 700 contains considerable amount of strong C-N bonds. Change in $CH_4$flow rate can effectively control the residual film stress, and typical surface roughness of 34.6 (rms) was obtained. Extreme]y high hardness (3952 Hv) and optical transmittance (95% at 633 nm) was achieved, which is suitable for a LIGA mask membrane application.

• 에너지공학
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• 제10권3호
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• pp.294-298
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• 2001

사용 후 핵연료의 고독성 장수명 핵종을 저독성 단수명 핵종으로 변환시키기 위한 미임계 핵변환로 연구가 진행중이다. 본 논문에서는 이러한 미임계 핵변환로에서 사용될 표적 시스템을 설계하기 위하여 표적시스템에 대한 열적, 구조적 분석을 수행하였다. 표적시스템의 열수력 분석에서는 diffuse plate를 삽입함으로써 빔창의 냉각효과를 증대시킬 수 있었다. 또한, 주요 인자인 빔창두께, 빔출력, 냉각재 유량 변화에 따른 빔창의 열적, 구조적 건전성 분석을 수행하여 표적시스템의 설계치를 설정하였다. 본 설계조건 하에서 빔창의 최대 온도 및 음력은 허용가능한 범위에 있음을 확인하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.142-145
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• 2008

Process simulation requires accurate and reliable data for a wide variety of material properties, ranging from thermal conductivity to flow stress curves. Traditionally such data are gathered from experimental sources, which has significant disadvantages in that not all of the required data is readily available, it may be from various sources that are themselves inconsistent, measurement of high temperature properties is expensive, and furthermore the properties can be sensitive to microstructure as well as to alloy composition. This article describes the development of a new multi-platform software program called JMatPro, which is based on CALPHAD methodology, for calculating the properties and behavior of multi-component alloys. A feature of the JMatPro is that the calculations are based on sound physical principles rather than purely statistical methods. Thus, many of the shortcomings of methods such as regression analysis can be overcome.

• 한국전산유체공학회지
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• 제16권4호
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• pp.92-99
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• 2011

In order to protect the turbine blade from working fluid of high temperature, many cooling techniques such as internal convection cooling, film cooling, impinging jet cooling and thermal barrier coating have been developed. With all other things, film-cooling has been widely used as the important alternative. In the present work, numerical analysis has been performed to investigate and to compare the film-cooling performance of various film-cooling hole schemes such as cylindrical, crescent, louver, and dumbbell holes. To analyze the turbulent flow and the film-cooling mechanism, three-dimensional Reynolds-averaged Navier-Stokes analysis has been performed with shear stress transport turbulence model. The validation of numerical results has been assessed in comparison with experimental data. The characteristics of fluid flow and the film-cooling performance for each shaped hole have been investigated and evaluated in terms of centerline, laterally averaged and spatially averaged film-cooling effectivenesses. Among the film cooling holes, the dumbbell shaped hole shows better film-cooling effectiveness than the other shaped holes. And the louver and cylindrical shaped hole show the worst film cooling performance, and concentrated flows on near the centerline only.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.417-420
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• 2006

The composition and structure of dendrite phase within $Zr_{76.11}Ti_{4.20}Cu_{4.51}Ni_{3.16}Be_{1.49}Nb_{10.53}$ bulk metallic glass (BMG) were confirmed by using an EPMA, XRD and TEM, respectively. The chief elements of dendrite phase were Zr-Ti-Nb and had a BCC structure. The thermal properties of this BMG have been then subsequently investigated by using a differential scanning calorimeter (DSC). The glass transition and crystallization onset temperatures were determined as $339.7^{\circ}C$ and $375.8^{\circ}C$ for this alloy, respectively. Mechanical properties have also been examined by conducting a series of uniaxial compression tests at various temperatures within supercooled liquid region under the strain rates between $10^{-4}/s$ and $3{\times}10^{-2}/s$. The deformation behavior of BMG composite within supercooled liquid region is similar to one of Vit-1 exhibiting amorphous single phase alloy. The flow stresses of BMG composite, however, are entirely higher than those of Vit-1 because dendrite phases are interfere with moving of atoms.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.237-248
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• 2013

Thermal stratification has continuously caused several piping failures in nuclear power plants since the early 1980s. However, this critical thermal effect was not considered when the old nuclear power plants were designed. Therefore, it is urgent to evaluate this unexpected thermal effect on the structural integrity of piping systems. In this paper, the thermal effects of stratified flow in two different safety injection piping systems were investigated by using a coupled CFD-FE method. Since stratified flow is generally generated by turbulent penetration and/or valve leakage, thermal stress analyses as well as CFD analyses were carried out considering these two primary causes. Numerical results show that the most critical factor governing thermal stratification is valve leakage and that temperature distribution significantly changes according to the leakage path. In particular, in-leakage has a high possibility of causing considerable structural problems in RCS piping.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.72-78
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• 2007

A diesel particulate filter causes progressive increase in back pressure of an exhaust system due to the loading of soot particles. To maintain the pressure drop caused by DPF under proper level, a regeneration process is mandatory when excessive loading of soot is detected in the filter. It is a major reason why the relation between the amount of soot and the pressure drop in a DPF becomes crucial. On the other hand, pressure drop varies with not only the soot loading but also conditions of exhaust gas such as mass flow rate. Therefore, the relation among them becomes complicated. Furthermore, the characteristics of heat transfer in a DPF is another crucial parameter in order for the filter to avoid thermal crack during regeneration period. This study presents characteristics of pressure drop under various conditions of soot loading and mass flow rate in catalyzed diesel particulate filter. This study also shows characteristics of heat transfer in DPF when high temperature gas flows into the filter. Experiments reveal that the soot loading and mass flow rate affect characteristics pressure drop independently. Experiments also indicate that the amount of coating material has little influence on pressure drop with changes in soot loading and mass flow rate. However, increased catalyst coating may lead to the improved heat transfer which is efficiency to reduce thermal stress of the filter.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.218-221
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• 2008

Hot Press Forming (HPF), an advanced sheet forming method in which a high strength part can be produced by forming at high temperature and rapid cooling in dies, is one of the most successful forming process in producing components with complex geometric shape, high strength and a minimum of springback. In order to obtain effectively and accurately numerical finite element simulations of the actual HPF process, the flow stress of a boron steel in the austenitic state at elevated temperatures has been investigated with Gleeble system. To evaluate the formability of the thermo- mechanical material characteristics in the HPF process, the FLDo defined at the lowest point in the forming limit diagrams of a boron steel has been investigated. In addition, the simulation results of thermo-mechanical coupled analysis of an automobile one-piece lower-arm part are compared with the experimental ones to confirm the validity of the proposed simulations.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.63-69
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• 2014

Domestic automobile companies have adopted drum type brake system for commercial vehicles. However recently those companies have been applying disc-brake system to solve vehicle control-instability and inefficient heat discharge performance of conventional drum brake system for a medium commercial vehicle. Because the kinetic energy of a running commercial vehicle is relatively high, the brake system should discharge lots of heat energy while braking. A ventilated type brake disc has been used to increase heat discharge performance of a brake system. The vent structure of a disc highly affects cooling efficiency. This paper compares thermal characteristics of three types of vent structure in JASO C421 braking condition. It is found that the slant bend type disc has the lowest temperature and thermal stress distributions in the braking condition.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.326-326
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• 2017

Climate warming is the issue on the global scale. Soybean can be seriously damaged when high temperature occurs during a reproductive stage such as the flowering and pod-setting period according to the Representative Concentration Pathway (RCP) (2021~2100) 8.5 scenarios. The weather in 2016 was very different from other years (average for 30 years from 1980 to 2010) ; the highest temperature was $33.7^{\circ}C$ which was higher $3.29^{\circ}C$ than average temperature from last 30 years and average rainfall was 26.5 mm, lower 140.9 mm than average rainfalls from other years. Especially, the highest temperature during soybean flow-ering and pod setting stage was $26.8^{\circ}C$ which was higher $0.1^{\circ}C$ and rainfall was 172.2 mm, higher 47.8 mm than other years from the first to the 20th in the October at soybean seed elongation stage. Soybean leaves were turned upside down by the drought stress during the flowering and pod-setting stage. The numbe-r of pods and seeds per unit area decreased 11.0% and 30.3% compared with the previous year, respectively. The ripening period was prolonged by 21 days because of high temperature and soil moisture contents due to the continual rainmade increase of the seed weight up to 15.6% and the yield decreased 7.1% compared to the previous year.