• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.135-135
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• 2007

AgInSbTe물질은 compact disc rewritable(CD-RW)와 rewritable digital versatile disc (DVD+RW)과 같은 상변화 기록매체에 널리 쓰여지고 있다. 본 논문에서는 기존 AgInSbTe조성에 Te가 증가되었을때 변화하는 상변화 특성에 대한 연구를 수행하기 위하여 ($Ag_{3.4}In_{3.7}Sb_{76.4}Te_{16.5})x(Te)1-x$의 조성 (x=1,0.9,0.8,0.7)의 벌크 및 박막시료를 제작하였고 열증착방식을 이용하여 200nm 두께의 박막을 형성하였다. 각 박막은 질소분위기에서 100-300도 범위에 1 시간동안 열처리 하였고 XRD와 UV-ViS-NIR Spectrophotometer룰 통해 각 조성의 구조 및 광학적 특성 분석을 살시하였다. 또한 as-deposited 박막에 대하여 4-point probe를 사용하여 면저항을 측정하였고 AFM (atom force microscopy)을 통해 표면분석을 실시하였다.

• 폴리머
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• 제31권1호
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• pp.14-19
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• 2007

탈미네랄화된 골분(demineralized bone particle, DBP)은 골/연골 형성의 강력한 유도인자로 사용된다. 본 연구에서는 용매 캐스팅/염 추출법을 이용해 함량별 DBP와 PLGA가 하이브리드화된 다공성 지지체를 실제 디스크 형태와 유사하게 제조하였다. 제조된 지지체의 특성을 분석하기 위하여 다공도, 표면 젖음성 및 물 흡수성을 측정하였다. 디스크 세포인 섬유륜 및 수핵 세포는 토끼로부터 분리하여 제조된 지지체에 각각 파종한 후, 지지체를 재조합하여 배양하였다. 지지체에 파종된 디스크 세포의 생존율과 증식률은 MTT(3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium-bromide) 분석 방법을 이용하였고, 면역결핍 쥐의 피하에 삽입하여 이들의 디스크 조직 형성 정도를 확인하였다. 피하에 이식된 지지체를 적출하여 육안으로 관찰하고 모폴로지의 변화를 확인한 후, 조직을 파라핀으로 고정시켜 슬라이드를 제조하여 hematoxylin과 eosin 염색을 수행하였다. 천연/합성 하이브리드 담체로서의 DBP/PLGA 담체가 PLGA 단독으로 사용하였을 때와 비교하여 볼 때 디스크 조직의 형성이 우수하였으며, 특히 20, 40%의 DBP가 함유된 지지체가 세포의 성장과, 디스크 조직화에 유리함을 확인하였다.

• 대한치과교정학회지
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• 제23권4호
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• pp.503-527
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• 1993

This paper describes a new method to create an animal model for TMJ internal derangement in the New Zealand white rabbits and the light and electron microscopical changes of posterior attachment of them. Twenty six rabbits(2.5-3.0kg), four normal and twenty two experimental, were used. The right disc of experimental animal was displaced anteriorly without sectioning the posterior attachment and tied to the zygomatic arch with nylon not to be reduced to the original position. The left TMJ was sham-operated to be compared with its right experimental one. Normal animals were sacrificed one day and eight weeks after experiment. Experimental animals were sacrificed one day, ten days, three weeks, five weeks and eight weeks after surgery respectively. They were fixed intravenously with $2\%$ glutaldehyde under general anesthesia and the samples of them were processed for light and electron microscopic examination. The purpose of this experiment is to make a suitable animal model of disc displacement without reduction for studying and understanding the cellular and morphologic events in posterior attachment of TMJ including early changes which were difficult to be observed in human TMJs. The results of this investigation suggest the following conclusions : 1. Authors induced anterior disc displacement surgically in rabbits with new method to examine histologic changes of posterior attachment. Tissue reactions of this model seem to be similar to those observed in human disc displacement. We think this animal model for anterior disc displacement may be used to explore and evaluate objectively the effects of many treatment modalities in disc displacements. 2. The animal disease model showed inflammation at early stage(one and ten days). At this stage there were mild-to-severe mononuclear inflammatory cell infiltration, numerous newly formed vessels, vessel dilatation and engormement and many fibroblasts. 3. At middle stage(three weeks), fibrosis occurred, where fibroblasts decreased in number, but their cytoplasm was profuse indicating high activity. Collagen fibers increased in number and the tissue looked more dense. 4. At late stage(five weeks and eight weeks) showed degenerative changes including perforation of posterior attachment, disintegration of collagen fiber bundles, degeneration of fibroblasts, metastatic ossification, and dystrophic calcification.

• Journal of Oral Medicine and Pain
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• 제33권4호
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• pp.387-394
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• 2008

목적 : 측두하악장애 환자에서 고가의 자기공명영상 진단을 대신하여 상대적으로 경제적인 진단방법으로 고해상도 초음파 영상을 도입하는데 있어서 그 정확성과 유용성을 확인하고자 하였다. 방법 : 측두하악장애의 임상적 증상 중 과두걸림, crepitation과 함께 통증을 호소하는 20명의 환자를 대상으로 하였다. 고해상도 초음파 촬영을 시행하였고, 고해상도를 가진 초음파촬영시의 결과를 비교하기 위하여, 통상적인 방사선 사진인 측두하악관절의 횡두개 촬영을 Accurad X-200으로, 그리고 Dental CT를 촬영하였으며, 이를 임상소견과 더불어 비교항목으로 선택하였다. 고해상도 초음파의 진단학적 가지 평가를 위하여 통계학적으로 감수성, 특이성, 양성예상치, 음성예상치 및 정확도를 계산하였다. 결과 : 고해상도의 초음파 영상은 골관절염성 변화를 진단하는데 67.5%의 정확도를 보였으며, 관절원판의 위치변화를 진단하는데 92.5%를 보였으나, 관절 주변조직인 관절낭, 관절원판 후조직 그리고 주변 인대의 이상을 측정하는데 있어서 정확도가 55%를 나타내었다. 결론 : 향후 초음파 영상을 얻기 위한 적절한 기기의 발전과 고주파수의 transducer 등이 개발되고 시술자의 훈련과 경험이 쌓이게 되면 매우 우수한 그리고 비침습적이고 접근이 용이하며 경제적인 진단학적인 검사방법으로서 일반적인 도입이 가능할 것으로 사료된다.

• 대한물리의학회지
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• 제2권1호
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• pp.93-99
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• 2007

Purpose : The aim of this study is to consider degenerative spine disease theoretically and compare plain radiography which is a basic study for low back pain with MRI in cases of degenerative lumbar spine disease to find out whether the abnormalities agree with each other. Methods : In 4 cases of lumbar degenerative disease, we studied the relation of the abnormalities such as disc space narrowing, spinal space narrowing, loss of lordosis and osteophytes on plain radiography with those on MRI of HIVD, spinal stenosis and spondylolisthesis. Results : Many abnormalities such as disc space narrowing, spinal space narrowing, loss of lordosis, osteophytes and change of cortex & bone marrow on plain radiography suggest HIVD, spinal stenosis, spondylolysis or spondylolisthesis on MRI. Conclusion : For low back pain patients, plain radiography is a basic study in diagnosis of HIVD, spinal stenosis, spondylolysis or spondylolisthesis but MRI or CT scan is necessary to develop(build) a treatment plan like an operation.

• Tribology and Lubricants
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• 제30권1호
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• pp.46-51
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• 2014

In this study, we attempted to characterize the physical meaning of the design parameters used for automobile passive dampers by considering the slit, disc, and hole, which influence the pressure characteristics. We also analyzed the change in the pressure characteristics when mixing various slits and discs. Finally, we used a computer simulation to implement lag according to nitrogen gas and analyzed the dependence of frequency on the nitrogen gas pressure.

• Tribology and Lubricants
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• 제29권1호
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• pp.1-6
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• 2013

Hydraulic transmission is the main component delivering power to the drive wheels of an excavator during forward and backward movement, and it has low speed, high torque and high speed, low torque gear change ratios as a forward/backward two-speed main function. It also has additional function of ensuring that the excavator is stably fixed on the ground with the built-in parking brake during excavation operations. In this study, optimal design specifications are determined by modeling and simulating about the multi-disc-type friction clutch, which is the main component improving the reliability of the hydraulic transmission for a 14-ton wheel excavator, and the friction properties of the transmission clutch are analyzed by performing sample tests.

• 한국기계가공학회지
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• 제6권4호
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• pp.86-91
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• 2007

The heat generated by the brake system of vehicles results in reduction of friction force on the brake surface and vibration when breaking. These problems play essential part in break's performance. To solve these problems, extensive research has been conducted such as drilling cooling holes on the brake pud, accommodating ventilated holes and etc. In this study, we suggest the compression of brake in circumferential direction in order to improve its cooling performance. And we analyzed comparing temperature distribution which is generated accomplishing heat analysis at each disc.

• 한국소음진동공학회논문집
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• 제19권12호
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• pp.1244-1251
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• 2009

In this paper the vibrational behavior of a multi-packet blade system having a cracked blade is investigated. Each blade is assumed as a slender cantilever beam. The coupling stiffness effect that originates from either disc flexibility or shroud is considered in the modeling. Hybrid deformation variables are employed to derive the equations of motion. The flexibility due to crack, which is assumed to be open during the vibration, is calculated basing on a fracture mechanics theory. In the paper, the results of the change in modal parameters due to crack appearance are presented. The influence of the crack parameters, especially of the changing location of the crack is examined.

• 한국군사과학기술학회지
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• 제9권2호
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• pp.70-76
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• 2006

The microstructure evolution during a hot forging of Waspaloy was investigated using the recrystallization model and FEM simulation. In order to obtain an uniform microstructure, hot forging was carried out by two step. The change of grain size during hot forging has a deep connection with dynamic recrystallization behavior. Avrami-type constitutive equation for the dynamic recrystallization was implemented into an user subroutine of 2D FE simulator. The evolution of grain structure in the two-step forging of Waspaloy was simulated using the 2D FEM user-subroutine. The detailed variation of microstructures due to dynamic recrystallization could effectively be predicted at various locations in a forged pancake.