• 비파괴검사학회지
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• 제25권2호
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• pp.81-86
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• 2005

본 논문에서는 반도체 패키지 내부결함의 비파괴 정량평가를 위한 ESPI 기법을 이용한 시스템 및 검사기 법을 제안하고 있으며, 검사시스템은 ESPI 검사장치, 열변형유도장치, 단열챔버로 구성되어있다. 기존 초음파, X-ray 기반의 검사기법에 비하여 측정시간 및 검사방법이 용이하며, 결함의 정량검출이 가능하다는 장점이 있다. 검사결과에서 대부분의 결함이 열 방출이 많은 칩 주위에서 박리결함으로 나타났으며, 원인은 층간 접착강도의 약화와 열분배 설계에서 문제점인 것으로 사료된다.

• 한국구조물진단유지관리공학회 논문집
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• 제12권5호
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• pp.55-64
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• 2008

유해 환경하에 노출된 숏크리트는 시간이 경과함에 따라 각종 유해이온의 침식으로 인하여 열화하게 된다. 본 연구에서는 이와 같은 환경에 노출된 숏크리트의 열화특성을 평가하기 위하여 황산염 및 산에 대한 화학적침식에 대하여 유해이온에 각각 60주 동안 침지한 숏크리트 코어 공시체를 대상으로 외관조사, 압축강도, 부착강도 및 기기분석을 실시하였다. 그 결과 용액의 종류에 관계없이 침지재령 60주에서 균열, 박리 등으로 인한 표면손상이 심각한 상태였으며, 압축 및 부착강도는 초기재령에서는 수중양생한 공시체보다 상회하는 결과를 보였으나 장기재령에서는 역전되는 현상을 보여주었다.

• 핵의학기술
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• 제27권1호
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• pp.11-22
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• 2023

Bone densitometry is a disease in which bones are easily broken due to metabolic bone disease, and DXA is used as a clinical standard test. Although DXA is a good method with good accuracy and reproducibility, it is frequently subject to test errors in testing and result analysis and analysis. Therefore, it is important to recognize the error issues that radiologists should basically be aware of when performing bone density tests, prevent erroneous diagnoses and treatments resulting from the results, and reduce the unnecessary costs associated with them. aim. The inspection must be carried out if the quality control of the equipment is basically continuously performed well before the inspection. Before starting the examination, the patient's age, sex, race, weight, pregnancy status, and any foreign objects that can be removed should be checked, and the examination should be performed in the correct posture. In addition, it is important to analyze results consistently. Radiologists, who play the most important role in ensuring accurate examinations, need to be aware of the potential for errors in advance and develop the ability to deal with the potential for errors in each examination. For that reason, regular education is considered essential.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.56-56
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• 2013

Sn-Ag 전해도금시 도금욕의 Sn 이온의 농도, Ag 이온의 농도, MSA 함량 및 인가 전류밀도 등의 인자들이 솔더의 조성과 표면형상에 미치는 영향에 관하여 연구하였다. 본 연구를 통하여 20의 미세피치와 15의 범프 높이를 가지는 공정 Sn-Ag 솔더 범프를 형성하였다. 도금된 솔더의 조성은 XRF와 ICP 분석을 통하여 확인하였고 형상은 광학현미경과 SEM을 통해 분석하였다. 또한 void 발생 여부 확인을 위해 FIB장비 및 X-Ray inspection장비를 사용 내부 Void 형상을 분석하였다. 전해 도금시 작용하는 주요 도금인자의 변경을 통해 15ASD에서 양호한 Bump를 구현하였다.

• 동력기계공학회지
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• 제15권4호
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• pp.25-30
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• 2011

This study is made to provide with a method for correcting the geometric distortion of the digital radiography image by analytical approach based upon the inverse square law and Beer's law. This study is aimed to find out and improve a mathematic model of nonlinear type. Variations in the alignment of the X-ray source, the object, and imaging plate affect digital radiography images. A model which is expressed in parameter values; e.g, angle, position, absorption coefficient, length, width and pixel account of radiography source, is developed so as to match the sample image. For the best correction of the digital image that is the most similar to the model image, a correction technique based upon tangent is developed; then applied to the digital radiography images of steel tubes. As a result, the image correction is confirmed to be made successfully.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.102-104
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• 2003

Laser weldability of aluminized steels of 0.8mm thick has been investigated. Test materials were cut from the commercial steels that were produced at the Coating Mill of POCOS. Test coupons for welding were prepared by using a conventional shearing machine and no additional edge treatment was peformed. Nd:YAG laser welding system was mainly applied to make weld specimens. Test results revealed that almost no spattering was observed even though the welding was peformed with no overlap joint clearance. Bead quality of aluminized steel laser weld was smooth and stable. According to x-ray inspection results, it was proved that the laser welds of aluminized steels were metallurgically defect free.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2000년도 춘계학술대회 발표논문집
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• pp.73-79
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• 2000

본 논문은 BCPS(Balanced canister purge solenoid valve) 의 Lab. 내구 시험 Spec. 결정 방법에 관한 것이다. BCPS 는 기존에 사용 중인 CPS(Canister purge solenoid valve) 의 응답성과 제어의 용이성을 좋게 하여 배기 가스 특성을 향상시키기 위해 CPS 내부에 Rubber 재질의 막(Diaphragm) 을 적용한 것이다. 하지만 이 Diaphragm 이 마모 등에 의해서 찢어지면, 오히려 배기 특성이 저하된다. 따라서 BCPS의 적용을 위해서는 이 Diaphragm 의 내구성이 검증되어야 하며, 이를 위해서는 새로운 신뢰성 시험 Spec. 의 개발이 필요하다. 본 연구에서는 BCPS Diaphragm의 검증을 위해 필요한 신뢰성 시험 Spec. 을 결정하였다. 이를 위해, X-ray Inspection System등을 이용하여 부압에 따른 Diaphragm 의 형상 변화 등을 관찰하였으며, 실제 차량에서 Diaphragm 에 걸리는 압력의 분포를 측정하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.174-176
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• 2005

On the basis of successful experiences and data from author's past experimental results of friction stir welding on thin aluminum plates, thick aluminum plate of high strength 2000 series has been carried out in this study. For various combination of rotating speed, welding speed and tool (RIWRC38-C) shape, the butt welded specimens has been prepared to check the metallurgical characteristics, hardness distributions and defects. From the results, feasible welding conditions have been obtained as 450 rpm rotating speed and 5 mm/min welding speed. Using these optimum welding parameters, 38.1mm-thickness A2519-T87 plates have been FSWelded in single pass. A good weld surface appearance and defects free weld zone has been observed in X-ray inspection. Softened region has been generated by dissolution of precipitates and coarsened microstructure in the stir zone after FSWeld.

• 한국해양공학회지
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• 제1권2호
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• pp.67-73
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• 1987

The feasibility for a practical use of underwater wet arc welding process is experimentally investigated by using low hydrogen and high oxide type electrodes and TMCP steel plates. Main results are summarized as follows: 1)The absorption speed of the coated low hydrogen and high titanium oxide type eletrodes becomes constant after about 30 minutes in water, and more steeping time in water does not influnce welding arc behavior. 2) By bead appearance and X-ray inspection, the high titanium oxide type electrode is better than the low hydrogen type in underwater arc welding process. 3) The mechanical properties of underwater wet arc welds depend upon welding conditions more than those of in-air welds, and the optimum welding condition can be obtained. 4) Because of quenching effect by rapid cooling rate in underwater wet welding, the maximum hardness of HAZ is increased relatively higher in underwater wet welding, process.

• Geomechanics and Engineering
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• 제13권1호
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• pp.141-159
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• 2017

A pick cutter is a rock-cutting tool used in partial-face excavation machines such as roadheaders, and its quality is a key element influencing the excavation performance and efficiency of such machines. In this study, pick cutters with hardfacing deposits applied to a tungsten carbide insert were made with aim of increasing their durability and wear resistance. They were field-tested by being installed in a roadheader and compared with conventional pick cutters under the same excavation conditions for 24 hours. The hardfaced pick cutters showed much smaller weight loss after excavation, and therefore better excavation performance, than the conventional pick cutters. In particular, the damage to and detachment (loss) of tungsten carbide inserts was minimal in the hardfaced pick cutters. A detailed inspection using scanning electron microscope-energy dispersive X-ray spectrometry and three-dimensional X-ray computed tomography scanning revealed no macro- or micro-cracks in the pick cutters. The reason for the absence of cracks may be that the heads of pick cutters are mechanically worn after the tungsten carbide inserts have been worn and damaged. However, scanning revealed the presence of voids between tungsten carbide inserts and pick cutter heads. This discovery of voids indicates the need to improve production processes in order to guarantee a higher quality of pick cutters.