• 대한약학회:학술대회논문집
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• 대한약학회 2001년도 Proceedings of International Convention of the Pharmaceutical Society of Korea
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• pp.249.1-249.1
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• 2001

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.162-169
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• 2003

Excavation by TBM can be characterized by a rock-machine interaction during the cutting process on a small scale, but on a large scale the interaction between the rock mass and TBM becomes very significant. For the planning and evaluation of TBM tunnelling it needs to understand rock fracture mechanism by a cutter or cutters on a small scale, and to estimate penetration rate, advance rate and utilization on a large scale. In this study rock chipping mechanism due to cutter-penetration is analysed by numerical simulation, showing that rock chipping is mainly occurred by tensile failure. Also, through the analysis of factors that affect on TBM procedures in various assessment systems, it is determined that the key elements that should be considered in the planning and evaluation of TBM tunnelling are classified into rock properties, the geological structures and properties of rock mass, and the structural and functional specifications of the machine. The user-friendly assessment tool is developed, so that penetration rate, advance rate and TBM utilization are evaluated from various input data. The tool developed in this study can be applied to a practical TBM tunnelling by understanding TBM tunnelling procedures.

• 터널과지하공간
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• 제18권6호
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• pp.457-464
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• 2008

암반 굴착기술의 고속화 및 정밀한 암반손상평가를 위해서는 암석의 동적파괴 메커니즘에 관한 연구가 중요하다. 본 연구에서는 충격파형 제어 Split Hopkinson Pressure Bar (SHPB) 시스템을 이용하여 모의 암석시료에 단계별 충격하중을 가하여 취성재료의 동적파괴 특성 및 동적손상메커니즘을 분석하였다. 실험시료의 손상도 평가를 위하여 충격실험 전후에 모든 시료에 대하여 P파 및 S파 속도를 측정하였으며, 탄성파 속도 감쇠정도에 따른 손상도를 평가하였다. 모의 연암 시료와 경암 시료의 탄성파 속도 감쇠비는 충격하중이 증가함에 따라 비슷한 수준으로 증가하는 경향을 보였으나, 최종 변형률의 경우 모의 연암 시료에서 현저히 높은 값을 나타내었다.

• 폴리머
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• 제31권2호
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• pp.123-129
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• 2007

세 종류의 폴리올레핀 복합재료의 기계적인 특성과 파괴인성 메커니즘이 연구되었다. 기계적 특성을 조사하기 위해 인장 시험 및 아이조드 충격 시험이 수행되었다. 균열 선단 주위의 파손 메커니즘을 정확히 조사하기 위해 2노치-4점 굽힘 기법이 도입/적용되었다. 광학현미경과 투과형 전자현미경을 이용하여, 폴리올레핀 복합재료의 균열 선단 주변 국부적인 파괴인성 특성들이 관찰되었다. 이를 통한 구체적인 관찰은, 폴리올레핀 복합재료의 균열선단 주변에 전단밴딩, 크레이즈, 입자-수지간 분리, 고무입자의 캐비테이션, 크랙 휭 및 크랙 분기 등과 같은 다양한 파괴인성 메커니즘들이 존재함을 보여주었다. 이러한 파괴인성 메커니즘들은 아이조드 충격 시험에서 보여진 파괴인성 값의 증가에 대한 실질적인 원인으로 보여진다. 본 연구를 바탕으로, 2노치-4점 굽힘 기법은 폴리올레핀 복합재료의 파괴 거동과 그와 관련된 파괴인성 메커니즘을 기술할 수 있는 충분한 정보를 제공하였다.

• Journal of Trauma and Injury
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• 제34권2호
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• pp.98-104
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• 2021

Purpose: Severe pelvic fractures are associated with genitourinary injuries, but the relationship between pelvic trauma and concomitant urethral injuries has yet to be elucidated. This study evaluated the incidence, mechanism, site, and extent of urethral injuries in male patients with pelvic fractures. Methods: A retrospective cohort study was performed involving patients with urethral injuries accompanying pelvic fractures who visited Pusan National University Hospital from January 1, 2014 to December 31, 2019. Demographics, mechanisms of injury, clinical features of the urethral injuries, concomitant bladder injuries, methods of management, and the configuration of the pelvic fractures were analyzed. Results: The final study population included 24 patients. The overall incidence of urethral injury with pelvic fracture was 2.6%, with the most common mechanism of urethral injury being traffic accidents (62.5%). Complete urethral disruption (16/24, 66.7%) was more common than partial urethral injuries (8/24, 33.3%), and unstable pelvic fractures were the most common type of pelvic fracture observed (70.8%). There was no definitive relationship between the extent of urethral injury and pelvic ring stability. Conclusions: The present study provides a 6-year retrospective review characterizing the incidence, mechanism, and clinical features of urethral injury-associated pelvic fractures. This study suggests that the possibility of urethral injury must be considered, especially in unstable pelvic fracture patients, and that treatment should be chosen based on the clinical findings.

• 한국공작기계학회논문집
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• 제16권2호
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• pp.14-22
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• 2007

In this paper, the acoustic emission(AE) behaviors were investigated with single-and 2-spot resistance spot welded SPCC specimens. Test specimens were welded horizontally and/or vertically according to the rolling direction of base netal in 2-spot welding. In the case of 2-spot welding, when tensile-shear test has below amplitudes: crack initiation $50{\sim}60dB;$ tear fracture $40{\sim}50dB$. And when cross tensile test has below amplitudes: early stage $75{\sim}85dB;$ yielding point $65{\sim}75dB;$ post yielding $40{\sim}60dB;$ plug fracture $70{\sim}80dB\;or\;90{\sim}100dB$. Also, from the b-value that is slope of AE amplitude, we knew that there are lots of low amplitudes if b-value is big(i.e., tensile-shear $specimen{\rightarrow}tear$ fracture or shear fracture), and there are lots of high amplitudes if b-value is small(i.e.. cross tensile $specimen{\rightarrow}plug$ fracture). As the results of fiacture mechanism analyses through AE amplitude distributions, change of the b-value represented fracture patterns of materials. Correspondingly, low amplitude signals appeared in crack initiation, and high amplitude signals appeared in base metal fracture. We confirmed that these amplitude distributions represented the change or degradation of materials.

• 콘크리트학회지
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• 제8권1호
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• pp.145-153
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• 1996

콘크리트의 파괴진행영역은 콘크리트의 균열선단의 브리징영역과 미세균열영역으로 구성되는 비선형영역으로서 콘크리트의 파기거동을 지배한다. 파괴진행영역을 고려한 파괴역학은 콘크리트에 유용하게 적용될 수 있으며 파괴진행영역 모델의 개발은 콘크리트의 파괴현상을 규명하는데 매우 중요하다. 본 논문에서는 콘크리트의 균열진행을 해석하기 위하여 선형 인장 연화곡선을 사용한 Dugdale-Barenblatt형 모델로 콘크리트의 브리징영역을 모델링하였고 이를 이산균열방법을 사용하여 단지 요소경계면에 파괴진행영역을 발생시켜 유한요소 해석하는 방법과 요소내의 불연속 균열면을 도입한 균열요소를 사용함으로써 이산균열방법의 결점을 보완한 해석방법을 제시하였다. 또한 해석 예를 통해 균열진행해석에 사용된 유한요소모델을 검증하였다.

• 비파괴검사학회지
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• 제18권4호
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• pp.278-291
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• 1998

연속섬유강화 복합재료의 경우 보강섬유의 파괴, 모재의 파괴, 섬유와 모재의 분리, 층간파괴 등의 복합적인 파괴현상이 동반되고 특히 균열성장과 균열성장 정지가 균열가교 현상 때문에 반복되므로 안정성장과 불안정성장이 불규칙하게 반복된다. 따라서 주균열 성장의 개시점과 불안정 파괴점에서의 파괴인성치를 정확하게 결정한다는 것은 매우 어려운 것이다. 본 연구에서는 CFRP에 대하여 파괴인성 실험과 병행하여 실시간으로 결함을 검출하는 새로운 방법인 AE분석법 및 비디오 마이크로 스코프를 이용하여 파괴과정을 기록하여 검토, 분석함으로서 손상의 정도와 파괴기구를 규명하였을 뿐만 아니라 주균열 성장의 개시점, 균열가교 역할을 하는 섬유다발의 파단점, 균열의 불안정 파괴 개시점을 찾아 이를 기초로 균열진전 저항곡선에 의한 파괴인성치를 평가하여 신뢰성 있는 파괴인성 측정법을 제시하였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제23권5호
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• pp.471-477
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• 2001

Failure to use effective methods of reduction, fixation, and immobilization may lead to nonunion with osteomyelitis, owing to the compound nature of most fractures of the mandible. Nonunion results in fibrous pseudoarthrosis at the fracture site with instability that, once formed, does not improve spontaneously. Once the nonunion with osteomyelitis secondary to fractures has become established, intermaxillary fixation and drainage of infected tissue should be instituted as early as possible, because the fixation & drainage enhances the patient comfort and hinders ingress of microorganisms & debris by movement of bone fragments. The authors treated three cases of nonunion with osteomyelitis by intermaxillary fixation, incision & persistent drainage on the previous fistula site and endodontic drainage of infected teeth in the fracture site of mandible. The localization & sequestration of the infected bone around the fracture was better performed persistently by natural homeostatic mechanism in $8{\sim}10$ weeks and the bony union was then attained without bone grafting.

• 대한족부족관절학회지
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• 제11권1호
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• pp.72-78
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• 2007

Purpose: This study is to analysis the outcome of patient with surgically treated Maisonneuve fracture and find out the factors that might influence the outcome. Material and methods: 20 patients who had surgical treatment due to Maisonneuve fracture between February, 2001 to March, 2005 were studied. The patients were followed for at least 1 year and average follow up period was 25 months. The average age was 41 years, 16 were male and 4 were female. Mechanism of injury according to Rouge-Hansen classification was supination-external rotation. In all cases, percutaneous screw fixation was applied proximal to tibiofibular syndesmosis. The screws were removed after 8 weeks under local anesthesis. Clinical, functional and radiographic results were evaluated. Results: 17 cases (85%) showed satisfying clinical and radiographic results. The mean functional score according to Ankle Scoring System was 91 (83 to 95). Complication occurred in 1 case with underlying systemic disease and 2 cases with initial ankle joint dislocation. Conclusion: Surgical treatment of Maisonneuve fracture showed relatively satisfying result. However, initial injury state and accompanying disease seem to have great effect on the result.