• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.311-314
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• 2001

This paper describes the simulation study, conducted on the propagation characteristics of AE signal in the connection of GIS. In the high voltage and large power system, the equipment with SF$\sub$6/ gas insulation which consists of the component part enclosed in the compressed gas has less affected by the environment than with air insulation. When the breakdown in the electric installation occurs, it takes much time to repair them though. Therefore it is very important to diagnose the propagation characteristics of AE signal in the GIS. So, in this investigation, we make a plane model of 362 kV GIS and modal and harmonic analysis to observe the vibro-acoustic property. Through the result of the analysis, we can make a further understanding on the vibro-acoustic characteristics of AE singnal in the connection of GIS.

• Journal of Welding and Joining
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• 제15권2호
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• pp.43-53
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• 1997

The complete joining method for dissimilar press punch materials and its real-time evaluation method is not available at present. Brazing method has been used for joining them, but it is known that the welded joint by the brazing has the lower bonding efficiency and reliability than the diffusion welding. The friction welding with a diffusion mechanism in bonding was applied in this study. This work was carried out to determine the proper friction welding conditions and to analyze mechanical properties of friction welded joints of sintered carbide tool materials (SKNM50 for the blade part of press punch) to alloy steel (SCM440 for the shank part of press punch) using aluminum (A6061 for the interlayer material) as an insert material between the sintered carbide tool materials and the alloy steel. In addition, acoustic emission test was carried out during friction welding to evaluate the weld quality.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.132.1-132
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• 2001

In this paper, we have studied for development of unmanned remote supervisory system using mobile communication network, not wire network, not to be affected by space or distance. The unmanned remote supervisory system consists of data processing unit main part and measuring systems (modules part)-temperature measuring module, humidity measuring module and human body sensing module. The data processing unit to collect and process informations of each measuring module has the functions of data communication between a mobile cellular telephone and measuring systems. Each measuring module has supervisory and warning functions for a target of supervision. And then we have designed each system and evaluated accuracy and reliability of the combined total system.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1468-1476
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• 1996

Surface integrity is dictated by the fabrication process of the metal part. In this work, steel specimens were prepared under various mechine conditions to achieve different degrees of deformation state. The tribological characteristics of the speciments were tested using a pin-on-disk type apparatus and other surface characterization tools. It is shown that though frictional characteristics are similar, the wear rate is significantrly affected by the properties of the surface. In the case of steel, surface cracks resulted in high wear despite the relatively high hardness of the specimen. Also, the sliding action were found to reduce the residual stress on the surface. These results indicate that there is a strong relationship between surface integrity and the tribological properties of steel, and therefore the machining condition should be optimized woth respect to tribological performance of a steel part.

• 한국자원식물학회지
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• 제5권1호
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• pp.11-23
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• 1992

The experiments tvere carried out to different temperature which affected growth, yield, proximate and antitumor activity in the Codonopsis lanceolata. Growth of aerial part and subterranean partwere best at 2$0^{\circ}C$ and lower 3$0^{\circ}C$. Components of fat, protein and fiber were best at 3$0^{\circ}C$. Wild C.fonceoforo had higher contents of fat, protein, fiber and ash as compared with cultur'ed C.lanceolataArginin was predominant amino acid in both wild and cultivated C.laceolata No significant differ-ence in the mineral contents was found between the wild root and the cultivated at 30'c inbiotronroom. No minerals difference in the contents was found between the cultivated temperature.The content of elements of inorganic metal differs according to the part. C. lanceolata were subjectedto preliminary antitumer screening test with Sarcoma 180 ascites and screening on V-79 cell. Thisexperiments were conducted in accordance with the total packed cell volume method and cytotoxicity method.

• 한국안전학회지
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• 제15권1호
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• pp.132-139
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• 2000

In this study, the fatigue life assessments of steel railway bridge in Japan National Railway were carried out. This railway bridge has been under in service from 1957, and fatigue damages were occurred at bead toe of upper part of vertical stiffeners of stringers, bead toes of scallop in lower part of vertical stiffeners in stringers and crossings of cross beams and stringers. From this study, a series of field tests were carried out by stress history measurement about above mentioned points. And as a results of stress histogram analysis, cummulative fatigue damage rate and fatigue life of these members should be calculate quantitatively. And from this estimation technique, cummulative fatigue damage rate and fatigue life of this railway bridge were strongly affected in passing tonage every year and the histories of live load.

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.277-284
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• 2004

This paper describes the influence of through-flow on the mixed convection in a parallel plates with the upper part is cooled and the lower part heated. When forced convection is imposed on natural convection, it is found that the flow pattern of mixed convection in the parallel plates can be classified into three patterns which were affected by Reynolds number. In such a mixed convection, the flow pattern plays an important role in the heat transfer process. In this study, thermo-sensitive liquid crystal suspension method is employed, then the visualization image acquired through the above method is processed by the color image processing technique and the two-dimensional velocity vector and temperature configuration are measured simultaneously.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.210-215
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• 2005

A three-dimensional numerical simulation is performed to investigate on a low Reynolds number mixed convection in a horizontal rectangular channel with the upper part cooled and the lower part heated uniformly. The three-dimensional governing equations are solved using a finite volume method. For convective term, the central differencing scheme is used and for the pressure correction, the PISO algorithm is used. Solutions are obtained for A=4, Pr=0.72, 10, 909, the Reynolds number ranging from $2.1{\times}10^{-2}$ to $1.2{\times}10^{-1}$, the Rayleigh number is $3.5{\times}10^4$. It is found that vortex roll structures of mixed convection in horizontal rectangular channel can be classified into three roll structures which affected by Prandtl number and Reynolds number.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.226-229
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• 2004

The temperature difference between die and workpiece has been frequently caused to various surface defects. The distribution and change for the temperature of forged part should be analyzed to prevent the generation of various defects related with the temperature. The surface temperature changes were mainly affected by the interface heat transfer coefficient. Therefore, the coefficient is necessary to predict the temperature changes of die and workpiece. The temperature calculated by FEM result might be well compared with the measured temperature. However, it is impossible to measure directly the temperature distribution of forged part. Therefore, the comparisons between measured temperature and predicted values are preformed by the microstructure in various temperature. Since the differences of microstructure could be obvious, the temperature criteria is set near by the incipient melting temperature. The predicted temperatures are well coincided with the measured values.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.338-341
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• 2004

The dimension of forged part is different with the die dimension by the various effects, such as, elastic deformation and thermal effect. And, the difference amounts are not same according to the forging conditions, for example, forging mode, flow stress, etc. Therefore, the use of FEA is effective to predict and update the required die dimension. However, the variables for FE simulation are also as many as variables in the experiment. The variables give very much effect to the accuracy of FE results. At first, the material model is very deeply affected to the estimated dimension of forged part. And the considering of loading and ejecting stages is also important to increase the dimensional accuracy. The experiment and FEA are performed to investigate the dimensional changes and accuracy in cold forging. Two types of upsetting are used to survey the effects of forging mode and stages.