• Journal of Chest Surgery
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• 제19권4호
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• pp.707-714
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• 1986

Funnel chest is the most common deformity of the sternum. It is characterized by a funnel shaped depression of the sternum with sharp angulation and lengthening of the costal cartilages, with the result that the cartilages point posteriorly. We have experienced with eight cases of funnel chest for 2 years recently, and they were corrected by the method of Ravitch operation with or without Kirschner`s wire. The postoperative course was uneventful. And now we report these with literature review.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.97-106
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• 2018

Improved load-following capability is one of the most important technical tasks of a pressurized water reactor. Controlling the nuclear reactor core during load-following operation leads to some difficulties. These difficulties mainly arise from nuclear reactor core limitations in local power peaking: the core is subjected to sharp and large variation of local power density during transients. Axial offset (AO) is the parameter usually used to represent the core power peaking. One of the important local power peaking components in nuclear reactors is axial power peaking, which continuously changes. The main challenge of nuclear reactor control during load-following operation is to maintain the AO within acceptable limits, at a certain reference target value. This article proposes a new robust approach to AO control of pressurized water reactors during load-following operation. This method uses robust feedback-linearization control based on the multipoint kinetics reactor model (neutronic and thermal-hydraulic). In this model, the reactor core is divided into four nodes along the reactor axis. Simulation results show that this method improves the reactor load-following capability in the presence of parameter uncertainty and disturbances and can use optimum control rod groups to maneuver with variable overlapping.

• 한국CDE학회논문집
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• 제2권3호
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• pp.175-185
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• 1997

Given the widespread use of the Finite Element Method in strength analysis, automatic mesh generation is an important component in the computer-aided design of parts and assemblies. For a given resolution of geometric accuracy, the purpose of mesh generators is to discretize the continuous model of a part within this error limit. Sticking to this condition often produces many small elements around small features in spite that these regions are usually of little interest and computer resources are thus wasted. Therefore, it is desirable to selectively suppress small features from the model before discretization. This can be achieved by low-pass filtering a CAD model. A spatial function of one dimension higher than the model of interest is represented using the Fourier basis functions and the region where the function yields a value greater than a prescribed value is considered as the extent of a shape. Subsequently, the spatial function is low-pass filtered, yielding a shape without the small features. As an undesirable effect to this operation, all sharp corners are rounded. Preservation of sharp corners is important since stress concentrations might occur there. This is why the LPF (low-pass filtered) model can not be directly used. Instead, the distances of the boundary elements of the original shape from the LPF model are calculated and those that are far from the LPF model are identified and removed. It is shown that the number of mesh elements generated on the simplified model is much less than that of the original model.

• 한국가스학회지
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• 제8권3호
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• pp.37-42
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• 2004

본 연구는 계절별 기후상태를 고려한 정성적 및 정량적 위험성 평가에 의해 최악의 시나리오와 가능성이 높은 시나리오를 설정하고, 비용-편익분석에 의해 시나리오별 안전관리비의 효율을 평가하였다. 그 결과, 최악의 시나리오는 비정상조업에서 유지보수 오류이었고, 가능성이 높은 시나리오는 HAZOP 구간 $\sharp$4에서 발생되는 가스 누출사고이었다. 또한 각 시나리오에서 전체 안전관리비에 대한 편익/비용과 효과적인 안전관리 항목을 평가할 수 있었다.

• 문화기술의 융합
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• 제10권3호
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• pp.145-154
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• 2024

행정 빅데이터를 활용하는 예측 모형을 운영하기 위해서는 정책의 변화 및 변동성 심한 데이터의 특성이 고려가 되어야만 한다. 이런 상황을 고려하여 본 연구에서는 Cut-off Voting Classifier(CVC) 알고리즘을 제안한다. 제안하는 알고리즘은 여러개의 약 분류기를 활용하여 적중률이 급격하게 하락하는 것을 방지하는 알고리즘이다. 본 연구에서는 제안하는 알고리즘을 실험을 통해 성능을 검증한다. 성능검증 결과 급격하게 예측모형 적중률이 하락하는 상황에서도 안정적으로 예측률을 유지한다는 것을 입증할 수 있었다.

• 한국항해항만학회지
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• 제35권7호
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• pp.589-596
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• 2011

Terminal market has rapidly crashed and market rates have taken a sharp plunge. The substantial throughput decrease resulted from the world economic downturn has been a finishing blow to the terminal operators in Busan. Every terminal operator is taking cost saving as its first priority and accelerating structural reform and downsizing. Under the desperate situation, the need of effective cost analysis would be highly required to effectively control operation cost and to develop new services to satisfy the different needs of the customers. Furthermore, terminal operators could reduce unnecessary activities and concentrate their resource on the more cost-effective process through the operation cost analysis. In order to suggest a new framework of the cost control of container terminals, this paper seeks to analyze terminal costs based on ABC approach by processing actual data.

• Journal of Welding and Joining
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• 제31권4호
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• pp.17-22
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• 2013

The excellent beam quality of high power fiber lasers are commonly used for remote welding applications in body job applications. The Welding speed and productivity is unmatched with any other welding technology including resistance spot welding or traditional laser welding. High tooling cost for clamping and bulky safety enclosures are obstacles which are limiting the use. With the newly developed Laser stitch welding gun we have an integrated clamping in the process tool and the laser welding is shielded in a way that no external enclosure is needed. Operation of this laser welding gun is comparable with resistance spot welding but 2-times faster. Laser stitch welding is faster than spot welding and slower than remote welding. It is a laser welding tool with all the laser benefits like welding of short flanges, weld ability of Ultra High Strength steel, 3 layers welding and Aluminium welding. Together with low energy consumption and minimum operation cost of IPG fiber laser it is a new and sharp tool for economic car body assembly.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 춘계학술대회 논문집
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• pp.303-310
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• 2001

The railroad under operation has very sharp curves and the state of ballast is somewhat deteriorated due to the traffic loads, which put some constraints in converting the conventional rails into CWR. In making CWR, the determination whether the ballast has sufficient capacity for resisting buckling must be made, quantitatively and qualitatively, and schemes to guarantee the required lateral resistance of ballast should be proposed. In this study, using the in-situ investigated data, the probability of buckling of CWR is given for several installation temperatures for CWR. The effect of tamping, DTS, and sleeper spacing are taken into account. The buckling probability is given as a function of curvature and installation temperature of CWR and works used to increase the ballast resistance capacity after tamping, i.e., DTS and reduction of sleeper sparing.

• Journal of Chest Surgery
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• 제23권3호
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• pp.609-615
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• 1990

Pectus excavatum is a congenital anomaly of the anterior chest wall with a sharp concave curvature of the body of the sternum, from above downward and from side to side, especially just before the junction of the glandioloxiphoid. There are two major operative procedures -"Ravitch" or "Wada" operation- for the correction of pectus excavatum. We used the modified Ravitch operation which consists of mobilization of the sternum, transverse osteotomy, and parasternal resection of the costal cartilages followed by placement of Marlex mesh using methyl methacrylate behind the sternum and suturing the edge of the Marlex mesh to the peripheral stump of the resected ribs. This was performed in a patient with severe pectus excavatum with good results at the Department of Thoracic and Cardiovascular Surgery Yonsei University College of Medicine in Seoul, Korea on January 12, 1989.anuary 12, 1989.

• Journal of Chest Surgery
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• 제39권1호
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• pp.48-55
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• 2006

배경: 아스피린과 플라빅스는 관상동맥 환자들에게 가장 흔히 사용하는 항혈소판 제제이나 수술 후 출혈 성향의 증가에 대한 우려 때문에 수술 5일에서 7일 전에 복용을 중단하는 것이 일반적이다. 본 연구에서는 이들 약제들의 지속적 사용이 무심폐기 하 관상동맥우회 술(Off pump coronary artery bypass grafting, Off pump CABG) 후의 결과에 어떤 영향을 미치는지에 관하여 조사하였다. 대상 및 방법: 2004년 3월부터 2005년 2월까지 Off pump CABG를 시행 받은 123명의 환자들을 대상으로 하여 수술 전후에 아스피린과 플라빅스를 끊지 않고 지속적으로 사용한 군(n=45, 36.6$\%$)과 적어도 수술 1일 이전에 끊은 군(n=78, 63.4$\%$) 사이에 수술 전후 혈소판, 헤모글로빈/헤마토크리트 수치, 수술 후 출혈량, 도관 개통률, 수술 시간 등을 비교하였다. 또한 대상환자들을 수술 전에 아스피린을 1달 이상 사용했던 장기 사용군과 그렇지 않은 군으로 구분하여 상기 요소들을 비교하였다. 결과: 수술에 의한 사망은 없었으며 출혈에 관한 합병증으로는 출혈에 의한 재수술과 상부 소화관 출혈이 각각 1예씩 있었다. 지속적으로 사용한 군과 그렇지 않은 군의 비교에 있어서는 수술 직후와 수술 후 1, 2일의 혈소판 수치가 지속적 사용군에서 유의하게 낮았으나(p=0.02, p=0.002, p=0.021) 수술 후 출혈량, 수혈 빈도, 출혈 관련 합병증 및 도관의 개통률에는 차이가 없었다 아스피린을 1달 이상 사용한 장기 사용군의 경우 그렇지 않은 군에 비하여 수술 전후의 혈소판 수치가 지속적으로 낮았으나 출혈량, 수혈 빈도, 합병증 및 도관의 개통률에는 차이가 없었다. 결론: 아스피린과 플라빅스의 Off pump CABG 전후의 지속적 사용은 수술 후 일시적인 혈소판 수치의 감소를 초래할 수 있으나 수술 후 출혈량, 수혈 여부, 수술 시간, 출혈과 관련된 합병증 및 도관의 개통률에는 영향을 주지 않았다. 그러므로 Off pump CABG에 있어서 아스피린과 플라빅스는 수술 전까지 지속적으로 사용하여도 될 것으로 생각한다.