• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.547-550
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• 2004

We present a multiscale scheme which describes the dynamic pictures of atoms in the multiple length-scale systems. Large-scale atomic systems are reduced to coarse grained system by the quasicontinuum, of which the dynamic pathways are rendered by the action-derived molecular dynamics proved effective for multiple time-scale problems such as rare events. Adatom diffusions on the metal (001) surface are selected for our numerical examples. The energy barriers of the diffusions and the real dynamic trajectories of the adatoms are calculated.

• Communications for Statistical Applications and Methods
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• 제31권1호
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• pp.65-85
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• 2024

The tail probability of a function of a multivariate random variable is not easy to estimate by the crude Monte Carlo simulation. When the occurrence of the function value over a threshold is rare, the accurate estimation of the corresponding probability requires a huge number of samples. When the explicit form of the cumulative distribution function of each component of the variable is known, the inverse transform likelihood ratio method is directly applicable scheme to estimate the tail probability efficiently. The method is a type of the importance sampling and its efficiency depends on the selection of the importance sampling distribution. When the cumulative distribution of the multivariate random variable is represented by a copula and its marginal distributions, we develop an iterative algorithm to find the optimal importance sampling distribution, and show the convergence of the algorithm. The performance of the proposed scheme is compared with the crude Monte Carlo simulation numerically.

• Earthquakes and Structures
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• 제19권3호
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• pp.175-188
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• 2020

The Hengda Group super high-rise building in Jinan City uses the frame-core tube structural system. With a height of 238.3 m, it is above the B-level height limit of 150 m for buildings within 7-magnitude seismic fortification zones. Therefore, it is necessary to apply performance-based seismic design to this super high-rise building. In this study, response spectrum analysis and comparative analysis of the structure are conducted using two software applications. Moreover, elastic time-history analysis, seismic analysis under an intermediate earthquake, and elastic-plastic time-history analysis under rare earthquakes are performed. Based on the analysis results, corresponding strengthening measures are implemented at weaker structural locations, such as corners, wall ends connected to framed girders, and coupling beams connected to framed girders. The failure mode and failure zone of major stress components of the structure under rare earthquakes are analysed. The conclusions to this research demonstrate that weaker locations and important parts of the structure satisfy the requirements for elastic-plastic deformation in the event of rare earthquakes.

• Clinical and Experimental Pediatrics
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• 제55권5호
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• pp.181-184
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• 2012

Voiding cystourethrography (VCUG) is a commonly performed diagnostic procedure for the evaluation of vesicoureteral reflux with urinary tract infection or congenital renal diseases in children. The procedure is relatively simple and cost-effective, and complications are very rare. The iatrogenic complication of VCUG range from discomfort, urinary tract infection to bacteremia, as well as bladder rupture. Bladder rupture is a rare complication of VCUG, and only a few cases were reported. Bladder rupture among healthy children during VCUG is an especially uncommon event. Bladder rupture associated with VCUG is usually more common in chronically unused bladders like chronic renal failure. Presented is a case of bladder rupture that occurred during a VCUG in a healthy 9-month-old infant, due to instilled action of dye by high pressure. This injury completely healed after 7 days of operation, and it was confirmed with a postoperative cystography. The patient's bladder volume, underlying disease, velocity of the contrast media instilled, catheter size, and styles of instillation are important factors to prevent bladder rupture during VCUG. Management of bladder rupture should be individualized, but the majority of infants are treated with the operation. In conclusion, bladder rupture is a rare complication, however, delicate attention is needed in order to prevent more dire situations.

• Asian Journal for Public Opinion Research
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• 제8권4호
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• pp.432-452
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• 2020

This study explored the representation of risks from the controversial Lynas rare earth refining as a risk event by five Malaysian online mainstream and alternative newspapers using qualitative content analysis. The aim is to uncover the role of the news media in the social amplification and attenuation of risks within the literature evidence as those roles are still uncertain. Content analysis is used to explore the online newspapers' roles guided by the Social Amplification of Risk Framework (SARF). The representations typified environmental, financial, health, occupational, property, radioactive, and technological risks and established connections between four risk types (environmental, financial, radioactive, and health risks). Radioactive risk was repeatedly associated with other risks, suggesting that the volume and information flow focused on radioactive risk as a key ingredient for amplification. This connection shows that the nature of the relationship between risks is multidimensional, contradicting the unidirectional type found in previous studies. Alternative online newspapers amplified and attenuated more risks, thus, providing more diverse coverage than mainstream sources. Consequently, this study provides evidence that risk representation from rare earth refining in a digital news environment is multidimensional and intensified or weakened in a multi-layered pattern. The stakeholders are engaged in a contestation by positioning their narratives to oppose or support their interests, which are amplified or attenuated by the online newspapers as social amplification stations.

• Communications for Statistical Applications and Methods
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• 제7권2호
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• pp.499-511
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• 2000

We consider a stable tandem network which consists of two M/M/1 nodes and study the probability that the total backlog exceeds a large level N. Since the excessive backlog is a rare event, it is difficult to estimate this probability efficiently by using the crude Monte Carlo simulation. Instead we perform the ;$h$-transform proposed by McDonald(1999) to obtain the twisted network, in which the node with the larger load is overloaded. Then we use it to run the fast simulation.

• Journal of Chest Surgery
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• 제28권5호
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• pp.510-512
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• 1995

Reexpansion pulmonary edema following treatment of pneumothorax and pleural effusion is a rare complication. However, because of possibility of its fatal outcome, physicians must be aware of this complication and every effort must be made to prevent its occurrence. We experienced 5 cases of reexpansion of pulmonary edema. One was complete tension pneumothorax and became death despite of intensive management. Remained four were 3 pneumothoraces and 1 pleural effusion and discharged without event, fortunately.

• Journal of Chest Surgery
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• 제23권5호
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• pp.1014-1016
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• 1990

Pseudocysts of lung by blunt chest trauma are rare lesion with 1 to 2 % incidence. The symptoms are nonspecific and misled or confused with lung abscess or congenital cystic disease of lung occasionally. Diagnosis is not difficult by radiographic findings and history of blunt chest trauma. There courses are benign and spontaneously absorbed and require no specific treatment mostly. Recently, we had the one case of 8 year-old female with traumatic lung cyst and its cavities filled the entire right lower lobe. The destruction of lung was severe, so, right lower lobectomy was done and recovered, discharged without event.

• Journal of Chest Surgery
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• 제26권6호
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• pp.507-509
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• 1993

Esophageal perforation, regardless of the etiology, is a catastrophic event. The importances of early diagnosis and an aggressive surgical approach in the management of such a potentially lethal situation are stressed, in fact the mortality rate is directly related to the interval between perforation and initiation of treatment. We experienced a rare case of esophageal rupture caused by compressed air which produce a rupture of the colon not infrequently, which was treated successfully by an aggressive surgical approach consisting of closure of the perforation and adequate drainage.

• Applied Biological Chemistry
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• 제50권4호
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• pp.245-252
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• 2007

FTA(fault tree analysis)는 system 오류 관리를 위한 정성적/정량적 기법으로 적용되고 있다. FTA를 적용한 PCR의 오류 관리 system의 구축을 위한 시범적 단계로서 PCR 실행의 여러 단계 중 가장 간단한 단계인 '반응액의 제조 및 PCR 기기 사용 단계'를 모델로 하여 분석하였다. PCR 실행시 발생할 수 있는 오류를 연역적 논리 방식에 의해 fault tree의 형태로 규명하였다. Fault tree는 오류 관리의 최상위 요소인 top event를 중심으로 중간 계층을 이루는 intermediate events와 최하위의 요소인 basic events로 세분하여 구성하였다. Top event는 '반응액의 제조 및 PCR 기기 사용 단계에서의 오류'; 중간계층 events는 '기기 유래 오류', '실험행위 유래 오류'; basic events는 '정전상황', 'PCR 기기 선정', '기기 사용 관리', '기기 내구성', '조작의 오류', '시료 구분의 오류'로 분석되었다. 이로부터 top event의 원인 분석 및 중요 관리점을 도출하기 위하여 정성적/정량적 분석을 실시하였다. 정성적 기법으로 minimal cut sets, structural importance, common cause vulnerability를 분석하였고, 정량적 기법으로 simulation, cut set importance, item importance, sensitivity를 분석하였다. 정성적 분석과 정량적 분석의 결과에서 '시료 구분의 오류'와 '기기 조작의 오류'가 제 1중요관리점; '기기 관리의 오류'와 '내구성에 의한 오류'는 제 2중요관리점으로 일치되게 나타났다. 그러나 '정전상황'과 '기기 선정의 오류'는 정성적 분석에서만 중요관리점으로 분석되었다. 특히 sensitivity 분석에서 '기기 관리의 오류'는 사용 시간이 경과함에 따라 가장 중요한 관리점으로 부각되었다. 결론적으로 FTA는 PCR 모델 case에 대한 오류의 원인 분석 및 그 방지를 위한 중요관리점을 제시함에 따라, 궁극적으로 미래에 PCR의 오류 관리 system을 완성할 수 있는 효과적인 방법으로 사료된다.