• 한국안전학회지
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• 제32권5호
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• pp.1-7
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• 2017

Forensic Engineering is the art and science of professionals qualified to serve as engineering experts in courts of law or in arbitration proceedings. Buses using compressed natural gas (CNG) trend to be extended in use internationally as optimal counterplan for reducing discharge gas of light oil due to high concern about environment. However, CNG buses is equipped with composite pressure vessels (CPVs); since the CPVs contain compressed natural gas, the risks in the case of accident is very high. In this study, the bursting test for the pressure vessel depending on the heat treatment conditions of the vessel in which the actual ruptured accident occurred, after the bursting test, the fracture pattern analysis had performed. The mechanical materials properties test using Instrumented Indentation Test had performed to confirm the mechanical properties for each heat treatment cases. Also, the fractography analysis and metallographic analysis had performed to find out the difference of each heat treatment case. By comparing normal vessel with abnormal vessel which have defect of heat treatment conditions in term of the bursting patterns and characteristics of containers using various forensic engineering methods, especially, it is possible to understand how important the heat treatment process is in the high pressure vessel unlike any product.

• Corrosion Science and Technology
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• 제18권3호
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• pp.102-109
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• 2019

The hydrogen diffusion and trapping model with a numerical finite difference method (FDM) was modified and extended to accommodate $H_2S$ corrosion and scale forming processes of high-strength steel under tensile stress condition. The newly proposed diffusion model makes it possible to clearly understand combined effect of tensile stress and $H_2S$ corrosion process on hydrogen diffusion behaviors. The core concept of this theoretical approach is that overall diffusion behavior is separated into diffusion process through two respective layers: an outer sulfide scale and an inner steel matrix. Diffusion coefficient values determined by curve-fitting permeation data reported previously with the newly proposed diffusion model indicate that the application of tensile stress can contribute to continual increase in the diffusivity in the sulfide scale with a high density of defect. This suggests that the scale with a lower stability under the stress condition can be a key parameter to enhance hydrogen influx in the steel matrix. Consequently, resistance to hydrogen assisted cracking of the steel under tensile stress can be decreased significantly.

• Structural Monitoring and Maintenance
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• 제10권3호
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• pp.221-242
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• 2023

Internal and external corrosion are common in pressure pipes used in a variety of industries, often resulting in defects that compromise their integrity. This economically and industrially significant problem calls for both preventive and curative technical solutions to guarantee the reliability of these structures. With this in mind, our study focuses on the influence of composite and metallic patch repairs on the limit loads of pipes, particularly elbows, the critical component of piping systems. To this end, we used the nonlinear extended finite element method (X-FEM) to study elbows, a priori corroded on the internal surface of the extrados section, then repaired with composite and metallic patches. In addition, the effect of the geometry of composite materials and metal patches was examined, in particular the effect of their thickness and material on the increase in limit loads of repaired structures. The results obtained provide information on the effectiveness and optimization of patch repair of corroded elbows, with the aim of increasing their service life.

• 한국인터넷방송통신학회논문지
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• 제24권2호
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• pp.147-153
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• 2024

X-ray는 주로 식품 검사, 의료 진단, 산업제품의 비파괴 검사에 사용되어 왔다. 최근에는 전기자동차의 핵심 부품인 배터리 검사에도 X-ray가 많이 활용되고 있다. 빠르게 증가하는 배터리 검사 수요를 고려할 때 수동 검사보다는 딥러닝 기반의 자동 배터리 검사의 도입이 필요하다. 딥러닝 성능은 기본적으로 학습 데이터 크기에 의존하는데 X-ray 응용 분야에서는 다량의 불량 데이터 확보가 쉽지 않다. 본 논문에서는 한정된 불량 데이터로부터 데이터 증강을 통해 학습, 검증, 테스트 데이터를 확보하고 학습 데이터 크기에 따른 X-ray 배터리 검사의 성능 변화를 확인하였다. 본 논문 결과를 통해 검사 성능 개선 프로세스에 대한 이해를 높일 수 있다.

• Archives of Reconstructive Microsurgery
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• 제14권1호
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• pp.1-13
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• 2005

Purpose: The purpose of this study is to present extended indications for the use of arterialized venous flaps in reconstructing soft tissue, tendon, nerve, blood vessel, and composite tissue defects of the hand of various sizes based on researches and clinical experiences of the authors. Moreover, procedures to achieve complete flap survival and postoperative results are presented. Materials & methods: This study is based on 154 cases of arterialized venous flaps performed to reconstruct the hand during the past 11 years. The most common cause of injury was industrial accidents with 125 cases. One hundred thirty patients or 84% of the cases had emergency operation within 2 weeks of the injury. The flaps were categorized depending on the size of the flap. Flaps smaller than $10\;cm^2$ were classified as small (n=48), those larger than $25\;cm^2$ classified large (n=42) and those in between medium (n=64). Classified according to composition, there were 88 cases (57.1 %) of venous skin flaps, 28 cases of innervated venous flaps, 15 cases of tendocutaneous venous flaps, which incorporated the palmaris longus tendon, for repair of extensor tendons of the fingers, and 17 cases of conduit venous flaps to repair arterial defect. There were 37 cases where multiple injuries to multiple digits were reconstructed. Moreover, there were 6 cases of composite tissue effects that involved soft tissue, blood vessels and tendons. The donor sites were ipsilateral forearm, wrist and thenar area, foot dorsum, and medial calf. The recipient sites were single digit, multiple digits, first web space, dorsum and palm of hand, and wrist. Results: There were seven cases (4.5%) of emergent re-exploration due to vascular crisis, and 3 cases of flap failure characterized by more than 50% necrosis of the flap. The survival rate was 98.1 % (151/154). In small flaps, an average of 1.01 afferent arteries and 1.05 efferent veins were microanastomosed, and in large flaps, an average of 1.88 afferent arteries and 2.19 efferent veins were anastomosed. In 8 cases where innervated flaps were used for reconstructing the palm of the hand, the average static two-point discrimination was $10\;(8{\sim}15)\;mm$. In 12 cases where tenocutaneous flaps were used, active range of motion at the proximal interphalangeal joint was 60 degrees, 20 degrees at the distal interphalangeal joint, and 75 degrees at the metacarpophalangeal joint. Conclusion: We conclude that the arterialized venous flap is a valuable and effective tool in the reconstruction of hand injuries, and could have a more comprehensive set of indications.

• Journal of Periodontal and Implant Science
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• 제29권3호
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• pp.483-509
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• 1999

Biodegradable barrier membrane has been demonstrated to have guided bone regeneration capacity on the animal study. The purpose of this study is to evaluate the effects of cultured calvarial cell inoculated on the biodegradable barrier membrane for the regeneration of the artificial bone defect. In this experiment 35 Sprague-Dawley male rats(mean BW 150gm) were used. 30 rats were divided into 3 groups. In group I, defects were covered periosteum without membrane. In group II, defects were repaired using biodegradable barrier membrane. In group III, the defects were repaired using biodegradable barrier membrane seeded with cultured calvarial cell. Every surgical procedure were performed under the general anesthesia by using with intravenous injection of Pentobarbital sodium(30mg/Kg). After anesthesia, 5 rats were sacrificed by decapitation to obtain the calvaria for bone cell culture. Calvarial cells were cultured with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. The number of cell inoculated on the membrane were $1{\times}10^6$ Cells/ml. The membrane were inserted on the artificial bone defect after 3 days of culture. A single 3-mm diameter full-thickness artificial calvarial defect was made in each animal by using with bone trephine drill. After the every surgical intervention of animal, all of the animals were sacrificed at 1, 2, 3 weeks after surgery by using of perfusion technique. For obtaining histological section, tissues were fixed in 2.5% Glutaraldehyde (0.1M cacodylate buffer, pH 7.2) and Karnovsky's fixative solution, and decalcified with 0.1M disodium ethylene diaminetetraacetate for 3 weeks. Tissue embeding was performed in paraffin and cut parallel to the surface of calvaria. Section in 7${\mu}m$ thickness of tissue was done and stained with Hematoxylin-Eosin. All the specimens were observed under the light microscopy. The following results were obtained. 1 . During the whole period of experiment, fibrous connective tissue was revealed at 1week after surgery which meant rapid soft tissue recovery. The healing rate of defected area into new bone formation of the test group was observed more rapid tendency than other two groups. 2 . The sequence of healing rate of bone defected area was as follows ； test group, positive control, negative control group. 3 . During the experiment, an osteoclastic cell around preexisted bone was not found. New bone formation was originated from the periphery of the remaing bone wall, and gradually extended into central portion of the bone defect. 4 . The biodegradable barrier membrane was observed favorable biocompatibility during this experimental period without any other noticeable foreign body reaction. And mineralization in the newly formed osteoid tissue revealed relatively more rapid than other group since early stage of the healing process. Conclusively, the cultured bone cell inoculated onto the biodegradable barrier membrane may have an important role of regeneration of artificial bone defects of alveolar bone. This study thus demonstrates a tissue-engineering the approach to the repair of bone defects, which may have clinical applications in clinical fields of the dentistry including periodontics.

• Journal of Chest Surgery
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• 제29권3호
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• pp.285-291
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• 1996

1973년 3월부터 1994년 12월까지 수술을 시행한 영아 및 소아 연령의 대동맥 교약증 157례를분석하 였다. 남아가 93명 여아가 64명 이 었고 연령은 1개 월부터 15세까지로 평균 23.8 $\pm$ 41.6개월이 었다. 영아 기의 주증상은 심부전이 었고(781113) 그 이상의 연령 에서 무증상이 빈번하였다(15/44). 단독 대동맥 교약증은 31례의 환아에서 있었고, 9례의 환아에서 심방중격결손이 있었으며(I군), 73명 의 환아에서 심실중격결손이 동반됐고(ll군), 44명의 환아에서 복잡 심기형이 있었다(III군).대동맥궁 의 형 성 부전은 17례의 환아에서 발견되었다. 수술은 71례의 환아에서 쇄골하동맥 편 성형술이 시행됐고, 단순 단단문합술이 32례, 조직편 대동맥 성형술이 26례, 확장 단단문합술이 27례, 기타 1례가 있었다, 전체 수술사망률은 17.2% (27/157)이었고, 재 협착률은 18.0% (28/157)이 었다. 수술합병증은 영아기에 서는 호흡기질환이, 그 이상의 연령 에서는 고혈압이 가장 많았다.

• 구강회복응용과학지
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• 제37권4호
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• pp.281-293
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• 2021

상악골 절제술을 받은 환자는 구개부의 결손으로 인해 연하, 저작, 발음 기능이 심각하게 손상되는데, 식사 시 비강과 코를 통한 누출이 있게 되고, 치아 및 치조제의 소실로 저작이 어려워지며, 구강과 비강이 분리되지 않아 과비음이 발생하는 등 삶의 질이 현저히 저하된다. 결손부를 보철적으로 재건하기 위해서는 폐색장치의 무게를 최대한 줄여 중력에 의한 탈락을 최소화하고, 폐색장치의 bulb를 결손부 내로 적절히 연장시켜 부가적인 유지, 안정을 얻도록 해야 한다. 본 증례는 종양의 재발로 인해 추가적인 상악골 절제를 받은 부분 무치악 환자에서 가철성 국소의치의 기본적인 설계 원칙을 적용하여 금속 구조물을 디자인하고, 기능 인상을 통해 유지, 안정, 지지를 향상시킨 폐색장치를 제작하였다. 환자는 개선된 안모 및 저작, 연하, 발음 기능 향상에 만족하였고, 경과관찰 기간 동안 안정적인 교합 및 구강위생관리를 보여 이를 보고하는 바이다.

• Journal of Chest Surgery
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• 제30권11호
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• pp.1069-1076
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• 1997

1992년 5월부터 1996년 6월까지 외과적으로 치료한 31례의 대동맥축착증의 중단기 성적을 검토하였다. 모두 31명의 환아중 19명(61.3%)이 신생아였으며 26명(83.9%)이 생후 3개월이내의 유아였다. 동반기형에 따라 세군으로 나누었는데 중요한 기형이 동반되지 않은 군(group I)이 9명, 심실중격결손을 동반한 군(group II)이 15명, 복잡심기형이 동반된 군(group III)이 7명이었다. 35.5%(11명)의 환아에서 대동맥궁의 형성부전이 동반 되었다. 수술방법으로는 17명의 환아에서 확장단단문합술, 7명에서 단단문합술과 쇄골하동맥편성형술을 함 께 시행(combined resection and flap pmcedure)하였고, 나머지 7례에서는 쇄골하동맥편성형술을 시행하였다. 술후 잔존협착은 술후 쟌존협착을 측정하였던 28례중 7례(25%)에서 발생하였고 쇄골하동맥편성형술후 6례중 2례(33.3%), 단단문합술과 쇄골하동맥편성형술을 함께 시행한후 7례중 없었으며, 확장단단문합술을 시행한 15례의 환아중 5례(33.3%)에서 발생하였다. 생존환아에서 평균 20.5개월의 추적기간후 술후 대동맥축착은 모 두 3례로 12%(3/25)였다. 이를 수술방법에 따른 빈도를 보면 쇄골하동맥편성형술후 6 恪\ulcorner2례(33.3%), 단단문 합술과 쇄골하동맥편성형술을 함께 시행한 7례중 없었으며, 확장단단문합술을 시행한 12례의 환아중 1례 (8.3%)에서 발생하였다. 대동맥축착증의 수술과 관련된 사망은 3례(9.7%)로 모두 복잡심기형을 동반한 군에서 발생하였다. 결론적으로 복잡기형을 동반하지 않은 경우(1, ll군)는 대동맥축착증의 수술과 관련된 수술사 망은 없었으며 복잡기형을 동반한 대동맥축착증의 수술은 높은 사망률을 보였다. 또한 대동맥궁형성부전증 이 있었던 경우에서 없었던 경우보다 더 높은 술후 잔존정착의 빈도를 보여 이의 적절한 치료가 요구되었다.

• 전자공학회논문지
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• 제50권5호
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• pp.183-190
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• 2013

본 논문에서는 불균일한 표면을 갖는 다결정형 솔라셀에서의 마이크로 크랙 검출을 위한 개선된 비등방 확산 모델 기반의 불량 검출 기법에 대해서 다룬다. 산업용 카메라를 이용하여 획득한 영상에서 CCD 센서의 특성으로 인하여 대각선 방향으로 발생한 마이크로 크랙의 밝기가 일정하지 않게 표현되는 경우가 발생한다. 이와 같은 특징으로 인하여 기존의 비등방성 확산 모델 기반의 마이크로 크랙 검출 알고리즘에서 충분한 반복확산이 이뤄지지 않을 경우, 대각선 방향으로 발생한 마이크로 크랙을 불연속적으로 검출하는 단점을 가지고 있다. 그러나 확산 횟수가 증가할수록 전체 알고리즘 수행 시간이 증가하며, 실제 마이크로 크랙보다 두껍게 검출하는 경향이 있다. 이러한 단점을 개선하기 위하여 기존의 동서남북 방향 기울기를 이용하는 비등방 확산 모델에 확장된 대각선 방향의 기울기를 추가로 적용하였다. 제안된 방법은 십자방향의 기울기와 확장된 기울기를 비교하고, 보다 큰 값을 확산계수 함수에 적용하는 방법이다. 이는 대각선 방향으로 발생된 마이크로 크랙의 정보를 반영하기 위한 것이다. Tsai et al.의 방법과 Ko and Rheem의 방법과 비교실험 한 결과, 본 논문에서 제안된 알고리즘이 기존에 제안된 알고리즘에 비하여 적은 반복횟수에서 마이크로 크랙을 우수하게 검출하는 것을 확인했다. 또한 기존 알고리즘에 비하여 실제 마이크로 크랙과 유사한 두께로 검출하는 것을 확인했다.