• Journal of Welding and Joining
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• 제29권1호
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• pp.115-122
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• 2011

This study is to propose an in-process monitoring system for micro resistance spot welding processes using minute accelerometer. A minute accelerometer is mounted on the upper moving electrode tip holder. With its high sensitivity and frequency response characteristics, accelerometer output signal has been successfully recorded and integrated twice to reflect electrode expansion during micro spot welding processes. The analysis of electrode expansion pattern was attempted to find its correlation with spot weld quality. Major previous findings1-6) regarding spot weld quality assessment with the electrode expansion signal in large scale resistance spot welding processes were proved to be true in this in-process monitoring system.

• Journal of Welding and Joining
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• 제17권6호
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• pp.32-37
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• 1999

Since stainless steel plates have good mechanical properties, weldability, appearance and resistance of corrosion, these are traditionally used for vehicles such as the bus and the train. And they are mainly fabricated by spot welding. But fatigue strength of their spot welded joint is considerably influenced by welding conditions as well as geometrical factors. Thus a reasonable and systematic criterion for long life design of spot welded body structure must be established. In this report, strain energy density was analyzed by using 3-dimensional finite element model about the IB-type spot welded lap joint under tension-shear load. Fatigue tests were conducted on them having various thickness, joint angle, lapped length and width. From their results, it was found that fatigue strength of the IB-type spot welded lap joints could be effectively and systematically rearranged by strain energy density at the edge of nugget.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.68-73
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• 2010

Welding conditions in process of spot welding must become optimum and need to guarantee stability and reliability of vehicle body considering dynamic load history. Because welding parameters in process of spot welding are various, it is difficult that the quality of spot weldment was included in the optimum levels. In this paper, we found the optimum welding conditions satisfying KS spot welding qualities using genetic algorithm and spot welding experiments of high tensile strength steel and galvanized steel. Those experiments were dissimilar weld and 2-lap spot welding. Genetic algorithm created random welding condition after that, selected optimum individuals by probability concept.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.60-62
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• 2005

The purpose of this study is to evaluate the effect of spot heating on the fatigue strength at the weldment. To do this, the transitional behavior of residual stress at the weld toe induced by spot heating was identified using FEA and experiment. The amount and distribution of residual stress at the weld toe strongly depends on the locations of spot heating. Based on the results, the proper spot heating condition was established. The fatigue strength of the spot-heated specimen increases compared with as-welded specimen.

• Journal of Welding and Joining
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• 제20권1호
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• pp.55-61
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• 2002

The automobile is made up of about twenty thousand parts. Some parts are formed by pressing and combined by spot welding. Among them, steel palate of fuel tank is formed in the metal mold and bending parts are jointed by spot and seam welding. To find weldability conditions of spot welding, clearance between two welding steel plates was made and after spot welding, weldability is evaluated by means of tensile shear load, nugget size and shape. Specimen used in this study was a mild steel of 1.2mm thickness and electrode was Cu-Cr alloy of 6mm diameter. When spot welding started, the clearance of two steel plates was changed 0mm, 3mm and 5mm step by step. The fractured surface of specimen after this test was observed by Optical Microscope to measure microstructure and nugget shape. When clearance of two specimen was 3mm and 5mm, strength and nugget size was decreased and nugget shape was not clear.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.485-488
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• 2000

In this study, the fatigue characteristic of spot weld specimen was studied by using the various specimen. The specimen types were tensile shear specimen welded one spot and two spot, and cross tension. The tensile tests and fatigue tests were executed to know the mechanical properties under static and fatigue load condition. In addition, the relationship was illustrated by finite element method.

• Journal of Astronomy and Space Sciences
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• 제5권2호
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• pp.97-109
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• 1988

The photometric behaviour of XY U Ma, an eclipsing binary showing photospheric and chromospheric activity, has been described by spot hypothesis. They are based on the all the available UBV light curves, which were carried out by Geyer since 1955. A "spherical rectangular" spot model shows very pronounced spot activities during the last 30 years. On the average, the spot covered about 16% of the visible hemisphere. Observational evidence for photospheric and chromospheric activities on the XY UMa and related systems are also discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.551-554
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• 2004

LED는 소비전력이 적고, 수명이 길어 LCD Backlight 용 광원으로 주목받고 있다. 현재 휴대전화기용 LCD에 많이 사용되고 있는 소형 LED Backlight의 경우 입광부에 LED의 개수가 육안으로 확인 가능할 정도의 Hot Spot이 존재한다. 이에 본 논문에서는 Reflector를 사용하여 광의 손실을 줄이고 도광판의 입광부에 산란 패턴을 설계하여 적용함으로써 도광판 입광부에서 122.7%의 휘도 상승효과와 73.4%의 휘도 균일도를 얻을 수 있었으며 이로 인해 Hot Spot을 감소시킬 수 있었다.

• 한국콘텐츠학회논문지
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• 제9권12호
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• pp.385-390
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• 2009

공기주입 정복술(pneumatic reduction) 및 방사선 배뇨성 방광요도 조영술(Voiding Cystourethrography: 이하 VCUG)는 일반적으로 영,유아에게서 행해지는데 이들 검사는 투시촬영과 spot 촬영으로 이루어지며 이때 투시촬영으로 인한 방사선 피폭은 불가피한 것이나 spot 촬영으로 인한 피폭은 투시 화면상의 관심영상을 capture하는 기능인 fluorograb을 이용하여 제거할 수 있다. fluorograb은 spot영상과 비슷한 진단가치를 지니고 있으며 최근 사용되고 있는 대부분의 투시촬영장비에서 지원되는 기능이지만 다수의 의사 및 방사선사는 이 기능을 인지하지 못하고 있거나 인지하고는 있으나 습관적으로 spot 촬영을 행하고 있는 실정이다. 이는 방사선에 매우 민감한 연령대에 속한 영.유아에서 적게는 10장 미만에서 많게는 20장 이상을 spot 촬영하게 되는 공기주입 정복술 및 VCUG에서 그 영향이 적지 않다 하겠다. 따라서 공기주입 정복술 및 VCUG 시행시 spot 촬영으로 인한 영.유아의 피폭을 줄이기 위한 방법으로 spot 촬영을 대신한 fluorograb을 제안하며 이로 인한 기존의 공기주입 정복술 및 VCUG 시행 시 영 유아의 피폭선량 경감 효과를 증명하고자 하였다. 공기주입 정복술 및 VCUG 의 진단에 fluorograb은 spot 촬영과 비슷한 수준의 정확도를 보이는 안전하고 유용한 방법이여 공기주입 정복술 및 VCUG 시행 시 spot 촬영을 대체할 수 있을 것으로 생각한다.

• Pediatric Infection and Vaccine
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• 제23권1호
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• pp.18-24
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• 2016

목적: 국내와 같이 결핵의 유병률이 높은 지역에서 결핵을 정확하게 진단하는 것은 중요하다. 본 예비연구는 국내의 소아청소년에서 결핵진단 시 TST 및 2가지 IGRA 검사법 (QFT-G 및 T-SPOT.TB) 간의 일치도를 알아보고자 하였다. 방법: 2014년 1월부터 2015년 4월까지 잠복결핵감염 또는 결핵질환의 진단을 위해 서울아산병원을 방문한 20세 이하 환자 중, TST, T-SPOT.TB 및 QFT-G 검사 중 최소 2가지 이상의 검사를 동시에 시행한 경우를 연구에 포함하였다. 이들의 의무기록을 후향적으로 분석하여 각 검사 간의 일치도를 평가하였다. 결과: 연구에 포함된 총 20명의 연령의 중앙값은 13.3세(범위: 3.8-18.1세)이었고, 이 중 11명은 면역저하와 관련된 기저질환이 있었다. T-SPOT.TB와 QFT-G 결과의 일치도는 90%였으며, TST와 T-SPOT.TB의 일치도는 50%, TST와 QFT-G의 일치도는 42.9%였다. T-SPOT.TB, QFT-G 및 TST의 결핵질환에 대한 특이도는 93.3%, 86.7% 및 58.3%였다. 결론: T-SPOT.TB과 QFT-G 간의 일치도는 높으나 TST와 T-SPOT.TB 또는 QFT-G 간의 일치도는 낮았다. 추후 국내 소아청소년의 정확한 결핵의 진단을 위한 각 검사들의 일치도 및 진단적 유용성에 대한 추가적인 연구가 필요하다.