• Journal of Welding and Joining
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• 제21권2호
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• pp.64-69
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• 2003

The bonding phenomena and mechanical property of duplex stainless steel during brazing have been investigated. The UNS32550 was used for base metal, and the MBF50 was used for insert metal. Brazing was carried out under the various conditions (brazing temperature : 1473K, 1498K, holding time : 0∼1.8ks). There were various microconstituents in the bonded interlayer because of reaction between liquid insert metal and base metal. In the early stage of brazing, BN is formed in the bonded interlayer and base metal near the bonded layer. Cr made is formed in the bonded interlayer. The amount of BN and Cr nitrides decrease with the increase of bonding temperature and holding time. Superior shear strength of 550MPa is obtained by restraining the formation of nitrides. (Received January 17, 2003)

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.470-474
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• 1997

Since the ceramic/metal joints is joined at high temperature, the residual stress will develop during when cooled from bonding temperature due to remarkable difference of thermal expansion coefficient between creamic and metal. Moreover, the edge of jointed interface makes singular stress field in the ceramic/metal joints and this singular stress field much influences on the strength of joints. In this study, The influence of residual stress, mechanical load and repeat thermal sysle was estimated in the ceramic/metal joints. According to this influence, the change of singular stress field was analyed and then strength test, X-ray measurement are performed.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.389-397
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• 1999

Recently the use of Pd catalyst have been continued to expand because of cost avaliabilityand performance advantages. Especially the Pd+Rh catalyst instead of the Pt+Rh catalyst had been used for most of three way catalysts because of the more stringent emission standards and its higher temperature effectiveness. The main purpose of this study is to investigate the design parameter impacts on the Pd+Rh cat-alyst for the automotive exhaust catalysts application. This study was investigated on the catalyst efficiency for the volume and the precious metal loading of the Pd+Rh ceramic monolithic cata-lyst. And experiments concerning the effects of volume and precious metal loading on Pd+Rh three way catalysts were conducted to examined the catalyst light-off temperature and conver-sion efficiency on higher volume demonstrated almost similar performance. But their effects on higher precious metal loading demonstrated considerably better performance.

• 한국건축시공학회지
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• 제12권2호
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• pp.183-193
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• 2012

Compressive property of high strength concrete with amorphous metal fibers subject to high temperature has been investigated. The measure of this investigation includes explosive spalling, weight loss, residual compressive strength, strain at peak stress, elastic modulus, and residual energy absorption capacity after exposure to $400^{\circ}C$, $600^{\circ}C$and $800^{\circ}C$. In addition to the amorphous metal fiber, two other types of fibers (polypropylene fiber and hooked-end steel fiber) were also included in this investigation for comparison. The experimental program was conducted with high strength concrete using several combinations of the fiber types. The testing result shows that the concrete with amorphous metal fibers plus polypropylene fibers shows a superior behavior than those using other combination or single fiber type ingredient.

• 한국분말재료학회지
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• 제7권1호
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• pp.19-26
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• 2000

Al-Cr-Zr metal powders were prepared by cryo-milling(-75$^{\circ}C$),ambi-milling(25$^{\circ}C$) and warm-milling(200$^{\circ}C$) to investige the effect of milling temperature. The morphogical changes and microstructural evolution of Al-6wt.%Cr-3wt.%Zr metal powder ball milling were investigated by SEM, OM and XRD. The cryo-milling at -75$^{\circ}C$ caused the more refinement of powder particle size than ambi-milling and warm-milling. The partic morpholgy of Al-Cr-Zr metal powders changed changes into spheroidal particles at 25$^{\circ}C$and spherical particles at 200$^{\circ}C$The spherical particles were formed by agglomertion and contiuous wrapping of the spheroidal particles. The calculated Al crystallite size in Al-Cr-Zr metal powders by the Scherer equation were refined rapidly for short milling time -75$^{\circ}C$compared with milling at 25$^{\circ}C$ and 200$^{\circ}C$.

• 반도체디스플레이기술학회지
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• 제3권3호
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• pp.31-35
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• 2004

A blue light emitting diode with 8 periods InGaN/GaN multi-quantum well structure grown by metal-organic chemical vapor deposition was fabricated with the inclusion of the metal-interconnection process in order to integrate the chips for light lamp. The quantum well structure provides the blue light photoluminescence peaked at 479.2 nm at room temperature. As decreasing the temperature to 20 K, the main peak was shifted to 469.7 nm and a minor peak at 441.9 nm appeared indicating the quantum dot formation in quantum wells. The current-voltage measurement for the fabricated LED chips shows that the metal-interconnection provides good current path with ohmic resistance of 41 $\Omega$.

• 한국정밀공학회지
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• 제32권11호
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• pp.969-976
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• 2015

In the present study, a numerical investigation of an insert injection molding process was carried out for the development of thermoplastic microfluidic chip plates with metal electrodes. Insert injection molding technology enables efficient realization of a plastic-metal hybrid structure and various efforts have been undertaken to produce novel components in several application fields. The microfluidic chip with metal inserts was proposed as a representative example and its molding process was analyzed. The important characteristics of the filling stage, such as the effects of filling time and thickness of the part cavity, were characterized. Furthermore, the detailed distributions of pressure and temperature at the end of the filling stage were investigated, revealing the significance of metal insert temperature.

• 한국결정성장학회지
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• 제15권6호
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• pp.217-221
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• 2005

EAF 더스트-점토계 소지에서 혼합비와 열처리 온도에 따른 소지 내의 중금속 총량을 측정하여 높은 증기압을 갖는 Cd, Pb, Zn 등의 중금속 성분의 휘발량을 분석하였으며 TCLP 분석을 통해 소지 내 중금속 성분의 안정화에 대해 평가하였다. 중금속 성분의 휘발은 EAF 더스트-점토의 혼합비와 열처리 온도에 크게 영향을 받으며 점토의 혼합비가 증가할수록 휘발이 효과적으로 억제되었다. 중금속 성분의 용출은 점토의 혼합비와 열처리 온도가 증가할수록 감소하였으며 안정화 효과가 큰 것으로 나타났다. EAF 더스트 20wt%-점토 800 wt%의 혼합비를 갖는 소지의 경우 중금속의 휘발과 용출이 거의 없었으며 XRD 분석 결과에 의하면 점토의 혼합비와 열처리 온도가 증가할수록 EAF 더스트-점토계 소지의 주결정상인 $(Zn{\cdot}Fe)Fe_2O_4$상과 quartz상의 회절강도가 감소하였으며, 이는 중금속의 휘발 억제 및 안정화 기구가 점토의 $SiO_2$ 성분에 의한 유리화 과정에 의한 것임을 나타내는 것으로 보여진다.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.388-395
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• 2015

The waste gate valve (WGV) for gasoline vehicles operate in a harsh high-temperature environment. Hence, WGVs are typically made of Inconel 713C, which is a type of Ni-based superalloy. Recently, the metal injection molding (MIM) process has attracted considerable attention for parts used under high-temperature conditions. In this study, an MIM analysis for the head and other parts of the WGV is conducted using a commercial CAE program Moldflow. Further, optimal manufacturing conditions are determined by analyzing flow characteristics at various injection times and locations. Moreover, to improve the accuracy of the analysis results, we compare the actual temperature of the mold during injection processing with that observed through the analysis. As the results, metal injection patterns of analysis are well in accord with these of short shot test. And the temperature variations of analysis is also very similar with those of feedstock when metal injection molding.

• 천문학회지
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• 제21권2호
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• pp.173-181
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• 1988

The usual method of classification for metal poor stars is based on the normal standard stars. In this study, we show that among the sample of stars classified by this method, a systematic bias in the observed classes of metal weakness is found and, also that this method is not appropriate for classification of metal poor stars, by showing that the spectral line dependences on the temperature and pressure in the extreme metal poor stars are different from those in the normal standard stars. Therefore, we suggest that the 3-dimensional classification system, like 2-dimensional MK system, is necessary for an accurate classification of metal poor stars.