• 지질공학
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• 제22권1호
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• pp.49-58
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• 2012

앵커두부에서의 많은 문제점들은 앵커두부가 외부에 노출되어 풍화에 직접적인 영향을 받고, 진동이나 외력에 의해 물리적인 변형과 손상을 많이 받기 때문이다. 본 연구에서는 기존 수압판 방식의 파괴원인을 분석하여 앵커두부에서 발생하는 문제점 해결을 위해 앵커두부의 지표면 근입방식을 제시하였다. 앵커두부처리 방식의 안정성을 기존방식과 비교, 검토하기 위하여 범용해석프로그램인 ABAQUS로 3차원 정밀 수치해석을 수행하여 하중조건에 따른 변위 및 응력분포양상을 분석하였고, 현장 적용성 검증을 위한 시험시공과 계측을 통해 적용 가능성을 평가하였다. 수치해석 결과는 최대수직응력이 9.73 MPa, 수직변위가 1.34 mm로 나타났고, 현장시험을 통하여 콘크리트 수압판의 변위가 근입형 지압판에 비해 3~4배의 큰 변위량을 보인다는 것을 확인하였다.

• 지질공학
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• 제20권1호
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• pp.13-23
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• 2010

암반사면의 전도파괴는 암반이나 토체가 기존 파괴면을 따라 미끄러지는 다른 파괴형태와는 달리 암주 혹은 암블록의 회전을 동반하는 파괴형태로 정의된다. 이는 사면방향에 대해 역방향으로 발달된 불연속면이 존재하는 구역에서 주로 발생하며, 불연속면의 지질학적 특성뿐 아니라 기하학적인 특성도 사면의 안정성을 판단하는 중요한 요소로 작용된다. 본 연구에서는 역방향 불연속면이 발달된 절토사면에 대해 안정성을 평가하였다. 일반적으로 암반의 파괴거동은 불연속체 특성을 가지고 있으나 최근 연속체 해석에서 불연속면을 모사하는 수치해석방법들이 많이 논의되고 있다. 본 연구에서는 연속체 해석인 유한요소해석에 불연속면을 이질적인 경계특성에 적용되는 계면요소를 이용하여 모사함으로써 불연속면이 고려된 사면의 거동특성을 파악하였다.

• 한국안전학회지
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• 제21권3호
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• pp.94-100
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• 2006

The goal of this study is to show the way to increase the safety of deteriorated PSC beam bridges by the to-box reinforcing method. This method is to change the open girder section into the closed box section by connecting bottom flanges of neighboring PSC girders with the precast panels embedding PS tendons at the anchor block. The box section is composed of three concrete members with different casting ages, RC slab, PSC beam, precast panel. This different aging requires a time-dependent analysis considering construction sequences. Reliability index and failure probability are produced by the AFOSM reliability analysis. Transversely five schemes and longitudinally two schemes are considered. The full reinforcing scheme, transversely and longitudinally, shows the highest reliability index, but it requires more cost for retrofit. The partial reinforcing scheme 4, 4-1 are recommended in this study as the economically best scheme.

• Journal of information and communication convergence engineering
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• 제7권2호
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• pp.157-163
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• 2009

With the wide usage of internet in many fields, networks are being exposed to many security threats, such as DDoS attack and worm/virus. For enterprise network, prevention failure of network security causes the revealing of commercial information or interruption of network services. In this paper, we propose a method of prevention of DDoS attacks for enterprise network based on traceback and network traffic analysis. The model of traceback implements the detection of IP spoofing attacks by the cooperation of trusted adjacent host, and the method of network traffic analysis implements the detection of DDoS attacks by analyzing the traffic characteristic. Moreover, we present the result of the experiments, and compare the method with other methods. The result demonstrates that the method can effectively detect and block DDoS attacks and IP spoofing attacks.

• 콘크리트학회지
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• 제10권6호
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• pp.269-280
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• 1998

최근에 섬유보강 콘크리트와 섬유보강 플라스틱과 같은 복합소재를 기존의 구조부재와 연루하여 적용하고자하는 연구가 많이 진행되고 있다. 이러한 첨단 복합소재를 적절히 사용하기 위해서는 이들 소재를 구조물 또는 그 일부에 적용할 시에 저항 메카니즘과 파괴양상에 대한 이해가 요구된다. 본 연구에서는 특별히 단면이 시멘트 복합소재를 층으로 갖거나 FRP 텐던 등으로 보강된 Bonded 및 Unbonded 프리스트레스트 콘크리트보의 비선형 휨거동을 예측할 수 있는 이론모델을 개발하고자 하였다. 본 모델은 한 개의단면으로 해석하는 Couple Method와 여러 개의 적층으로 나눈 Layered Method의 중간적인 모델이라고 할 수 있는 블록개념(Block Concept)이 적용되었다. 주어진 하중에 대한 처짐을 구하기 위하여 N개의 축력에대한 평형조건과 N개의 휨에 대한 평형조건을 이용하여 보 전체의 2N 개의 변수를 구하였다. 본 모델은 여러 형태로 배근된 Bonded 그리고 Unbonded 프리스트레스트 콘크리트보의 휨 거동을 성공적으로 예측하였다.또한 취성적인 FRP 텐던이 파괴됨에 따른 보의 갑작스런 하중저하 이후의 점진적인 내력증가도 성공적으로 모사하였다. 이는취성적인 FRP텐던으로 보강된 프리스트레스트 보의 전반적인 하중-처짐을 추적하는데 유용하다.

• Journal of Chest Surgery
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• 제24권1호
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• pp.54-63
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• 1991

Post-thoracotomy pain is so severe that lead to postoperative complications, such as sputum retention, segmental or lobar atelectasis, pneumonia, hypoxia, respiratory failure due to the patient`s inability to cough, deep breathing and movement. Many authors have been trying to reduce the post-thoracotomy pain, but there is no method of complete satisfaction. In 1974, Nelson and associates introduced the intercostal nerve block using the cryoprobe. The application of cold directly to the nerves causes localized destruction of the axons while preserving the endoneurium and connective tissue, thereby introducing a temporary pain block and able to complete regeneration of intercostal nerves. One hundred and two patients, who undergoing axillary or posterolateral thoracotomy at the Department of Thoracic and Cardiovascular Surgery in Korea University Medical Center between April 1990 and August 1990, were evaluated the effects of cryoanalgesia for the post-thoracotomy pain reduction. The patients were divided into two groups: Group A, control, the patients without the cryoanalgesia[No.=50], Group B, trial, the patients with cryoanalgesia[No.=52]. Before the thorax closed, in the group A, local anesthetics, 2% lidocaine 3cc, were injected to the intercostal nerves[one level with the thoracotomy, one cranial and caudal intercostal level and level of drainage tube insertion]. In the group B, cryoprobe was directly applied for 1 minute at the same level. Postoperative analgesic effects were evaluated by the scoring system which made arbitrary by author: The pain score 0 to 4, The limitation of motion score 0 to 3, The analgesics consumption score 0 to 3, The total score, the sum of above score, 0 to 10. For the evaluation of immediate analgesic effects, the score were evaluated at the operative day, the first postoperative day, the second postoperative day, and the seventh postoperative day. The effects of incision type, and rib cut to the post-thoracotomy pain were also evaluated. The results were as follows; 1. The intercostal block with cryoanalgesia reduced the immediate postoperative pain significantly compare with control group. 2. The intercostal block with cryoanalgesia improved the motion of the operation side significantly compare with control group. 3. The intercostal block with cryoanalgesia reduced the analgesics requirements at the immediate postoperative periods significantly. 4. The intercostal block with cryoanalgesia lowered the total score significantly compare with control group. 5. The intercostal block with cryoanalgesia were more effective to the mid-axillary incision than to the posterolateral incision 6. The intercostal block with cryoanalgesia were more effective to the patients without rib cut than to the patients with rib cut. 7. No specific complication need to be treated were not occurred during follow-up.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.966-970
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• 2011

The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.651-656
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• 2002

In general, the most important problem in slope stability analysis is that there is no definite way to describe the natural three-dimensional Joint network. Therefore, the many approaches were tried to anlayze the slope stability. Numerical modeling approach is one of the branch to resolve the complexity of natural system. UDEC, FLAC, and SWEDGE are widely used commercial code for the purpose on stability analysis. For the purpose on the more appropriate application of these kind of code, however, three-dimensional distribution of joint network must be identified in more explicit way. Remaining problem is to definitely describe the three dimensional network of joint and bedding, but it is almost impossible in practical sense. Three dimensional joint generation method with random number generation and the results of generation to UDEC have been applied to settle the refered problems in field site. However, this approach also has a important problem, and it is that joint network is generated only once. This problem lead to the limitation on the application to field case, in practical sense. To get rid of this limitation, Monte Carlo Simulation is proposed in this study 1) statistical analysis of input values and definition of the applied system with statistical parameter, 2) instead of the consideration of generated network as a real system, generated system is just taken as one reliable system, 3) present the design parameters, through the statistical analysis of ouput values Results of this study are not only the probability of failure, but also area of failure block, shear strength, normal strength and failure pattern, and all of these results are described in statistical parameters. The results of this study, shear strength, failure area, pattern etc, can provide the direct basement on the design, cutoff angle, support pattern, support strength and etc.

• 사물인터넷융복합논문지
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• 제10권2호
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• pp.109-114
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• 2024

높은 데이터 신뢰성을 요구하는 엔터프라이즈 저장시스템은 데이터 손실 및 장애 시 복구를 위해 RAID(Redundant Array of Independent Disks) 시스템을 적용하고 있다. 특히 RAID 5는 패리티를 여러 저장장치에 분산 저장하여 공간 효율성과 안정성을 보장하였다. 그러나 저장장치의 용량이 서로 다를 경우 가장 작은 용량의 저장장치기준으로 RAID가 구축되어 저장공간의 낭비가 발생한다. 따라서 이러한 자원관리 문제를 해결하기 위한 연구가 필요하다. 본 논문에서는 SSD(Solid State Disk)로 구성된 RAID에서 각각의 독립적인 NAND 플래시 메모리 블록을 내부뿐만 아니라 외부 SSD와 RAID 그룹을 묶는 방법을 제안한다. 이 방법은 SSD 내부의 블록 정보를 RAID 시스템에 전달하는 정책과 RAID 시스템으로부터 전달된 물리적인 주소를 RAID 그룹으로 묶는 정책으로 구분된다. 이 방법을 통해 서로 다른 용량의 SSD를 RAID로 묶을 때 자원의 낭비가 발생하지 않는 RAID를 유지할 수 있다. 마지막으로 실험을 통해 제안하는 방법의 효과를 증명한다.

• Journal of Chest Surgery
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• 제33권1호
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• pp.88-95
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• 2000

Pulmonary lymphangioleiomyomatosis is a chronic destruct8ive disease of the lung affecting women of childbearing ages which eventually leads to respiratory failure. Lung transplantation is the only conclusive therapeutic measure because this disease responds poorly to other therapies, To date only a few reports in the literature describes the clinical experience of the bilateral sequential lung transplantation of this rare condition. We performed a bilateral sequential lung transplantation on a 32-year-old woman suffering from lymphangioleiomyo-matosisw. The heart-lung block was harvested from a 51-year-old donor. We transplanted the left lung first through the clam-shell incision. As the hemodynamics deteriorated suddenly during the dissection of the right lung the right lung was transplanted under the cardio-pulmonary bypass. Although the patient's lung function was initially satisfactory the patient died of sepsis and subsequent cardiogenic shock at the postoperative 18th day. Autopsy findings showed infection of Candida albicans on the pericardium and the left lung which had been initiated possibly from the left bronchial anastomosis site,. Through detailed review of the clinical course we concluded that lung transplantation could have been performed safely on this disease provided that early diagnosis and proper management or the oppor-tunistic infection have been carried out.