• Journal of Conservation Science
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• v.26 no.1
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• pp.13-24
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• 2010

This study examined each handiwork method of 4 filigree artifacts from Neungsan-ri temple site in Buyeo, Korea through material characteristic and microstructure analysis. As a result, it was indicated that all of the artifacts have comparatively higher purity than 22.7K and some of filigree artifacts showed that gold is alloyed with silver at a certain ratio. Gold thread that decorates surface showed thickness of 0.2~0.8mm and displayed various forms of section. Gold granule indicated that 2 or 3 granules are adhered together and they are 0.3~0.8mm in diameter. Trace of soldering was observed from gold thread and gold granule joints on surface and it confirmed a possibility of being soldering using gold solder through componential analysis. Also, it reveals a surface decorated with pigments such as cinnabar(HgS) and black.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.4
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• pp.13-21
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• 2011

Seismic structure pounding between adjacent superstructures may induce the destruction of pier and bridge superstructures and cause local damage that leads to the collapse of the whole bridge system. The pounding problem is related to the expansion of joints, gap distance and seismic response of the abutments. In this research, methods of the contact element approach, the linear spring model, the Kelvin-Voigt model and the Hertz model were studied to analyse the pounding characteristics. The shaking table test for a model specimen such as a bridge superstructure with elastomeric bearings was performed to evaluate the contact element approach methods. Relationships between the time history response from the numerical analysis results and the measured response from the shaking table test are compared. The experimental results were not well matched with the numerical analysis results using the existing pounding stiffness models. Therefore, in this study, coefficients are proposed to calculate the appropriate pounding stiffness ratio.

• Magazine of the Korea Concrete Institute
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• v.7 no.4
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• pp.119-128
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• 1995

This paper summarizes experimental results for studying feasibility and structural behavior of' a half slab which is getting popularity in recent building construction in favour of the savings in manpower, coats, and construction period. 17 specimens were tested to investigate and analyze the flexural strength of precast concrete slab, half slab, and half slab-wall joint. The primary variables of the testing program were: thickness of precast concrete slab, truss mesh shape, and type of loadings. Test results show that the flexural strength of precast concrete slab in reverse loading is lower than the design strength, but the flexural strength of precast concrete slab, half slab and half slab-wall joint in direct loading is higher than the design srength. No horizontal cracks were found in the connection between insitu concrete and precast concrete slab. The flexural strength of half slab and half slab-wall joint was the same as that of reinforced concrete members. This study concludes that there will not be any structural problem in using a half slab reinforced by truss mesh if props spacing of 2.0m-2.5m, cleanness, and rough finishing between precast concrete and insitu concrete slab are kept.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.3
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• pp.9-18
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• 1999

In this study, Metallugical properties between Sn-3.5Ag, Sn-37Pb eutectic solders and Au/Ni/cu substrate according to time span above the melting point were investigated. A conventional reflow soldering machine wert used for this study and time span above the melting point was determined by changing peak soldering temperature and conveyor speed. As results, scallop type intermetallic compounds of $Ni_3Sn_4$ were formed at joint interface and no Cu-Sn compounds were found at all; Ni layer performed as a barrier for Cu diffusion. As the peak soldering temperature increased, thickness of the intermetallic compound layer increased; maximum thickness of the scallop-layer was 2.2$\mu\textrm{m}$. The shape of scallops were transformed from hemi-sphere type to elliptical shape with smaller size. Micro-hardness of the solder joint decreased as the eutectic structure of Sn-3.5Ag and Sn-37Pb increased.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.1-6
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• 2004

The requirements for harsh environment electronic controllers in automotive applications have been steadily becoming more and more stringent. Electronic substrate technologists have been responding to this challenge effectively in an effort to meet the performance, reliability and cost requirements. An effect of the plasma cleaning at the ECM(Engine Control Module) alumina substrate and the intermetallic compound layer between Sn-37wt%Pb solder and pad joints after reflow soldering has been studied. Organic residual carbon layer was removed by the substrate plasma cleaning. So the interfacial adhesive strength was enhanced. As a result of AFM measurement, conductor pad roughness were increased from 304 nm to 330 nm. $Cu_6/Sn_5$ formed during initial reflow process at the interface between TiWN/Cu pad and solder grew by the succeeding reflow process, so the grains became coarse. A cellular-shaped $Ag_3Sn$ was observed at the interface between Ag-Pd conductor pad and solder. The diameters of the $Ag_3Sn$ grains ranged from about 0.1∼0.6 $\mu\textrm{m}$. And a needle-shaped was also observed at the inside of the solder.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.467-474
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• 2010

Stainless steel sheets are widely used as the structural material for railroad cars and commercial vehicles. Structures made of stainless steel sheets are commonly fabricated by gas welding, For the fatigue design of gas welded joints such as fillet joints, it is necessary to obtain design information of the stress distribution at the weldment as well as the fatigue strength of the gas-welded joints. Further, the influence of the geometrical parameters of gas-welded joints on stress distribution and fatigue strength must be evaluated. in this study, ${\Delta}P-N_f$ curves were obtained by fatigue tests. and, the ${\Delta}P-N_f$ curves were rearranged on the basis of the ${\Delta}{\sigma}-N_f$ relation for the hot-spot stresses at the gas-welded joints. These results, were used for conducting an accelerated life test(ALT) From the experiment results, an acceleration model was derived and factors were estimated. The objective is to obtain the information required for the analysis of the fatigue lifetime of fillet welded joints and for data analysis by the statistic reliability method to save time and cost and to develop optimum accelerated life prediction plans.

• Conservation Science in Museum
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• v.12
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• pp.1-7
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• 2011

The seated stone Buddha(Bon5190) of National Museum of Korea initially consisted of some 90 fragments, making it difficult to guess its overall appearance. Under a restoration work which lasted four months, the fragments were joined together, giving shape to a seated Stone Buddha in Bhumisparsa(earth touching) mudra and an associated figure of Bodhisattva missing the face. The statue was made from a single stone block by digging out the center. Traces of lacquer coating and a gilded layer above the lacquer coat were found in various parts. Polarizing microscopy and XRD analysis revealed that the stone was zeolite, a mineral formed through diagenesis of volcanic glassy ashes from trachytic tuff (Nuldaeri) and dacitic tuff (Guryongpo). In Korea, zeolite deposit found mostly in Gyeongsangbuk-do, in places like Yeonil, Guryongpo, Gampo and Ulsan. The restored statue of seated Buddha proved very similar in appearance to the seated stone Buddha of Deoksa Temple in Cheongdo-gun, Gyeongsangbuk-do (housed in Yeongsanjeon Hall). The scroll inside the statue, containing information about the background and circumstances of creation of this Buddhist sculpture, indicates that the monk Seung-ho took part in it as the head sculptor-monk.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.118-118
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• 2009

자동차의 경량화, 안전성 그리고 내식성 향상을 위하여 고강도 강판 및 도금 강판의 적용이 증가하면서 자동차 산업의 많은 부분에서 적용되는 저항 점용접에서도 고강도 강판과 도금강판의 적용이 증가하는 추세이다. 이에 따라 고강도 강판과 도금 강판의 낮은 용접성을 개선하기 위하여 기존의 단상 AC 용접기에서 전류 파형의 형태를 개선한 인버터 DC 용접기가 차체 조립라인에서 많이 사용되고 있다. 본 연구에서는 고강도 강판의 저항 점용접의 연속타점 시 단상 AC용접기와 인버터 DC용접기의 전극의 연속타점 수명의 차이를 비교하고 분석하기 위해 590MPa 급 전기아연도금강판을 이용하여 AWS 규격에 연속타점실험을 기준으로 단상 AC 와 인버터 DC 용접기의 연속타점 실험을 실시하였다. 연속타점실험 중에 전극의 형상관찰을 위해 100타점 간격으로 carbon paper를 이용해 전극 직경 변화를 관찰 하였으며, 100 타점간격으로 동저항을 측정하고 인장 전단 시편과 Peel test 시편을 제작하여 연속타점 시 단상 AC와 인버터 DC 용접기의 저항 점용접 연속타점 수명을 비교 분석하였다. 그리고 연속타점 실험 후 사용된 전극의 표면과 단면 형상을 각각 OM, SEM, EDX로 분석하여 전극 표면의 Zn과 합금화 된 전극의 합금층을 분석하였다. 그 결과 590MPa급 전기아연도금강판의 저항 점용점 연속타점 수명평가에서 인버터 DC 용접기가 단상 AC 용접기보다 200타점 더 우수한 연속타점 수명을 보유하였다. 특히 인장강도 기준 측면에서는 인버터 DC 용접기의 전극 연속타점수명은 매우 우수하다.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.15 no.3
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• pp.155-159
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• 2015

Citrin deficiency (OMIN #605814) is an autosomal recessive disorder caused by the SLC25A13 gene mutation with abnormal biochemical findings, including increased serum ammonia, citrulline, arginine, galactose, serum threonine-to-serine ratio, serum pancreatic secretory trypsin inhibitor, and alpha-fetoprotein. Citrin deficiency can manifest in three ways: in newborns as neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD), in older children as failure to thrive and dyslipidemia caused by citrin deficiency (FTTDCD), and in adults as citrullinemia type 2 (CTLN2) with recurrent hyperammonemia and neuropsychiatric symptoms. We report a 35-day-old asymptomatic patient with citrin deficiency who had abnormal biochemical findings.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.9
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• pp.789-794
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• 2014

The FPGA is used to the high speed digital satellite communication on the Digital Signal Process Unit of the next generation GEO communication satellite. The high capacity FPGA has the high power dissipation and it is difficult to satisfy the derating requirement of temperature. This matter is the major factor to degrade the equipment life and reliability. The thermal control at the equipment level has been worked through thermal conduction in the space environment. The FPGA of CCGA or BGA package type was mounted on printed circuit board, but the PCB has low efficient to the thermal control. For the FPGA heat dissipation, the heat sink was applied between part lid and housing of equipment and the performance of heat sink was confirmed via thermal vacuum test under the condition of space qualification level. The FPGA of high power dissipation has been difficult to apply for space application, but FPGA with heat sink could be used to space application with the derating temperature margin.