• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2006년도 전력전자학술대회 논문집
• /
• pp.203-205
• /
• 2006

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• Journal of Korean Neurosurgical Society
• /
• 제30권10호
• /
• pp.1241-1244
• /
• 2001

The authors report a very rare case of tuberculous spondylitis combined with a schwannoma of spinal cord. A 39- year-old man was admitted because of paraparesis(G1/G2). MRI showed severe cord compression at two different levels. One was by the bulged soft tissue and subligamentous abscess extending from T7 to T9 and the other was by an intradural extramedullary cord tumor at the level of T1-2. At first operation, T8 corpectomy and T7-9 plate fixation with autogenous iliac bone graft were performed. After then, Paraparesis was improved(G2/G3) postoperatively. The second operation underwent two weeks later. The tumor was totally removed and shortly after second operation, paraparesis was markedly improved(G3/G4). Histological diagnosis were tuberculous spondylitis and schwannoma, respectively. The authors reviewed this case where good surgical outcome was obtained by two stage operation.

• Journal of Gastric Cancer
• /
• 제10권2호
• /
• pp.63-68
• /
• 2010

Purpose: Remnant gastric cancer (RGC) are generally detected at advanced stages or infiltration of adjacent organs. We retrospectively reviewed the surgical outcomes and clinicopathologic results of remnant gastric cancers that have operated during fourteen years in one institution of Korea. Materials and Methods: 34 patients who were diagnosed with RGC at Ajou University Hospital from April 1995 to October 2009 were enrolled. We analyzed the features of previous operation, and according to these results, surgical outcomes and clinicopathologic results for RGC were analyzed. Results: Of 34 patients, 20 patients had previously undergone distal gastrectomy for malignant disease, and 14 patients for benign disease. The period between previous operation and surgery for RGC in the patients underwent operation for malignant disease was shorter than that in benign patients (P<0.001). In surgical field, 31 patients (91.0%) were resected and curative resection was possible in 23 patients (67.6%). When 31 patients who underwent resection for RGC were divided into previous malignant and benign disease, there was no significantly different in terms of surgical outcomes and pathologic findings between two groups. Meanwhile, the patients who recently (after 2005) underwent surgery for RGC showed less advanced stage compared with the patients who underwent surgery before 2004. Conclusions: Resection was possible in the higher proportion (91.0%) of patients diagnosed with RGC compared with previous reports. The cause of previous operation did not effect on the surgical outcomes for surgery of RGC. Recent trend of RGC is to increase the proportion of early stage gastric cancer. Therefore, surgeons should consider curatively surgical resection for RGC the regardless of pattern of previous operation.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.119-120
• /
• 2006

Prioritizing the design specifications among many alternatives is necessary at the stage of concept design. Design specifications have trade-offs between cost and performance, and the relationships among them, in the standpoint of various functional requirements, are complex. AHP(Analytic Hierarchy Process) method is one of the most popular ways of solving the priority setting problem. However, it is impossible to monitor the interim findings in the middle of the process, it is hard to predict the difference when changing pairwise comparison conditions, and the operation done by one person makes it hard to share the process simultaneously. This paper shows a new method of priority setting in this kind of decision making problem. This method is designed to support the realtime priority setting among many design specifications with regards to many functional requirements. A new algorithm and visualization methods are introduced, and the usability is verified in an exemplary concept design stage.

• Journal of Gastric Cancer
• /
• 제2권2호
• /
• pp.85-90
• /
• 2002

Purpose: Perforated gastric cancer (PGC) is rare and occurs in $1\∼4\%$ of all gastric cancers. Possible dissemination of tumor cells at the time of perforation of the gastric carcinoma has been a matter of concern. The intraoperative determination of what kind of operation should be done and how extensive the lymphnode dissection should be still remains controversial. The purpose of this study is to evaluate the factors influencing the survival and to determine the optimal treatment for PGC. Materials and Methods: A total of 42 patients were operated on for a perforated gastric carcinoma at Soonchunhyang University Chunan Hospital from 1983 to 2000. the age and the sexes of the patients, the location of perforation, the diameter of perforation, the histologic type of the tumor, the depth of wall invasion, the absence or presence of lymph node metastasis / distant metastasis, the stage of disease, the type of operation, and the outcomes were examined. Statistically significant differences were analyzed by using Fisher's exact test. Results: The stage distributions according to the UICC classification were 1 case of stage I, 6 cases of stage II, 17 cases of stage III, and 11 cases of stage IV. An emergency gastrectomy was done in 26 patients ($61.9\%$), with a 5-yr survival rate of $44\%$. The survival of patients was significantly influenced by the depth of wall invasion, the lymphnode metastasis, distant metastasis, the stage of disease, and the type of operation. Conclusions: an emergency gastrectomy is the treatment of choice for most patients with resectable PGC. Choosing more a optimistic surgical approach for potentially curative cases of PGC should be one way to increase the patient's survival rate.

• 수산해양기술연구
• /
• 제56권3호
• /
• pp.223-229
• /
• 2020

We analyzed the cutting mechanism of laver harvesting machine in the sea area near Gooam Port in Goheung, Jeollanam-do, and investigated the change and efficiency of laver collecting operation in the working ship. The laver working ship slides uniformly from the bow to the upper part of the laver collecting machine on the deck and cuts the wet laver attached to the bottom of the net at the blade of the havesting machine. The laver farming net, which was loaded with laver turrets on the deck by gravity and collected primitives, consisted of a ship structure that led to the stern side and into the sea. The working ship operation is in harvesting process while driving in a S-shape that is separated by one space to efficiently collect the laver net. During laver working ship operation, the speed was 0.51 m/s in the access stage, 0.56 m/s in the havesting stage, and 0.52 m/s in the exit stage. Considering the cutting edge life and production efficiency of the laver harvesting machine, it is appropriate to harvest 1.15 to 1.26 kg/rpm by operating at a rotational speed of about 700 to 800 rpm rather than forcibly harvesting the product at high speed. On the deck of the working ship, 959.7 kg of starboard and 1048.7 kg of center were 964.7 kg of port side. Based on the starboard, 9.3% of the central part and 0.5% of the port side appeared. The reason for this was due to the difference in harvest time according to the turning direction of the working ship.

• 한국수자원학회논문집
• /
• 제30권3호
• /
• pp.269-278
• /
• 1997

저수지 운영의 기초가 되는 운영률은 대부분 과거기록 유입량중 최대 혹은 최소의 극한치 자료를 이용하거나 평균치 자료를 이용하여 도출하기 때문에 실제 운영에서 발생할 수 있는 불확실성에 대처한 기대편익 산정이나 운영방안 수립에는 적절히 이용할 수 없다. 또한 지금까지 개발된 대부분의 운영률은 유입량을 포함하여 모든 운영변수를 이미 알고 있다는 확정론적 방법에 기초하고 있어 유입량의 불확실성을 반영하지 못하는 단점이 있다. 이를 개선할 수 있는 방법으로 추계학 분석기법에 의한 운영률을 개발할 수 있는데 이는 저수지 상태방정식의 구성요소인 유입량의 추계학적 특성을 시계열상에서 이산화된 천이확률로 처리하여 모형에 적용할 수 있다. 확정론적 방법에 의한 저수지 운영방안을 개선시키기 위하여 추계학적 방법에 의한 저수지 운영률을 개발하였다. 본 연구에서는 이와같은 방법론에 따른 양해 추계학적 동적계획기법을 이용하여 충주 저수지 시스템의 최적 운영 방안을 마련하였다. 개발된 운영률을 홍수기를 제외하고는 Lag-1 Markov 모형의 기본가정을 충실히 따르고 있어 저수지 운영률로의 이용이 가능하며, 운영단계의 유입량을 적절히 예측할 수 없는 현실에서 전단계의 유입량과 적용단계의 저류량만을 이용하는 저수지 운영률의 개발이 가능하다.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 2004년도 추계학술대회 및 정기총회
• /
• pp.527-530
• /
• 2004

This paper presents an optimization formulation for resource scheduling in Critical Resource Diagramming (CRD) of production scheduling networks. A CRD network schedules units of resources against points of needs in a production network rather than the conventional approach of scheduling tasks against resource availability. This resource scheduling approach provides more effective tracking of utilization of production resources as they are assigned or 'moved' from one point of need to another. Using CRD, criticality indices can be developed for resource types in a way similar to the criticality of activities in Critical Path Method (CPM). In our supply chain model, upstreams may choose either normal operation or expedited operation in resource scheduling. Their decisions affect downstream's resource scheduling. The suggested optimization formulation models resources as CRD elements in a production two-stage supply to minimize the total operation cost

• Journal of Chest Surgery
• /
• 제30권11호
• /
• pp.1062-1068
• /
• 1997

1989년 8월부터 1996년 1월까지 세종병원 흉부외과에서는, 단일심실성 교정을 요하는 환자에 대하여 중간 단계의 수술적 치료로서 양방향성 Glenn수술을 총 105례에서 시행하였으며, 이들에 대한 최종단계의 Fontal 수술을 1992년 12월부터 시행하기 시작하여 1996년 2월까지 총 42례에서 양방향성 Glenn수술로부터의 Fontal 전환술을 시행하였다. 진단으로는 단일심실증이 19례, 삼천판막폐쇄증이 11례, 양대혈관우심실기시증류가 9례, 기타 3례였다. 이들의 양방향성 Glenn수술의 시기는 환자연령 2개월에서 8세까지로 중앙연령 값이 12.5개 월이었으며, Fontan 전환술의 시기는 환자연령 1세 5개월부터 9세 7개월까지로 중앙연령 값이 59.6 개월이었다. 두 수술단계 사이의 대기기간은 10개월에서 6년 3개월까지로 평균 33.88+17.85 개월이었다. 두 수술 사이의 기간 동안 18례에서 임상적으로 의미있는 체-폐동맥간 혹은 체-폐정맥간 부행혈관이 발생하였다. Fontan 전환술의 수술방법으로는 대부분의 경우 Gore-Tex도관포편을 이용한 측면 Tunneling을 하였으며 2.5~6 mm 크기의 fenestration을 만들었다. 수술 후 병원 사망례는 5례였으며, 사망원인은 4례에\ulcorner 저심장박출증, 떼는 폐혈증이었다. 만기 사망례는 5례였으며 수술 후 6 개월에서 2년 후에 발생하였는데, 중요 원인은 혈전증 1례, Fontan failure 에 의한 심장이식후 사망 떼, Protein Loosing Enteropathy 1례, Plastic Bronchitis 1례, 그리고 폐렴 1례 등이다. 그외의 생존환자들은 수술후 7개월에서 4년 2개월까지 평균 21.97$\pm$10.82개월 동안 추적 결과 양호한 상태를 보이고 있다. 양방향성 Glenn수술후 Fontan 전환술 사이의 기간을 2년을 기준으로 나누었 을 때, 2년 이내에 Fontal 전환술을 시행한 군(12례)이 그 이후의 시행군(21례)과 비교하여 더 좋은 결과를 보였다. 즉 병원사망률 1/16 대 4/26, 만기사망률 1/16 대 4/26,부행혈관의 발생률 2/16 대 16/26(P<0.05) 이었다. 결론적으로 Fontan수술의 위험요소가 있는 단일심실성 교정수술 대상의 환자에 있어서 양방향성 Glenn수술 단계 후, 연령 등의 원래의 위험요소의 재평가후에 Fontan 전환술의 시기는 2년 내에 시행하는 것이 좋으리라 사료된다.

• Journal of Chest Surgery
• /
• 제34권8호
• /
• pp.604-610
• /
• 2001

배경: Stanford 제A형(type A) 대동맥 박리증은 상행대동맥이나 대동맥궁의 인조혈관 치환 수술 후에도 남은 대동맥의 가강이 확장되거나 파열의 가능성이 있기 때문에 철저한 추적관리가 필요하다. 연세대학교 세브란스병원에서는 1984년 6월부터 2000년 3월까지 Stanford 제A형의 대동맥박리 수술이 124예 있었다. 수술 후 가강의 확장이나 파열로 재수술한 6예에서 Marfan 증후군과의 관련성 등 원인을 조사하고 재수술의 방법과 결과, 재수술의 위험을 줄일 수 있는 방법 등을 알아보고자 한다. 대상 및 방법: 처음 대동맥 박리로 수술시급성인 경우가 4예 만성이 2예였으며 이중 3예가 Marfan 증후군이였다. 1예를 제외한 모든 환자에서 상행대동맥내에 내막파열이 있어 대동맥판막의 폐쇄부전의 정도에 따라 상행대동맥 인조혈관 치한수술(2례) 또는 Bentall 수술을 시행하였으며(3례) 1예는 여러 개의 가강과의 연결부위가 있는 만성 박리 환자로 Bentall 수술과 더불어 대동맥궁까지 인조혈관으로 치환을 하였다. 재수술은 평균 67.6개월(4개월-14년4개월) 후에 시행하였는데 1예는 만성 하행대동맥 박리 및 동맥류로 1예는 염증성 가성동맥류로 나머지 4예는 급성대동맥 박리로 재수술을 시행하였다. 수술은 하행흉부대동맥만을 치환한 경우가 1예, Hemiarch로 시행한 경우가 1예 그리고 나머지 4예는 원위부 상행대동맥에서 대동맥궁을 포함하여 근위부 또는 중간부위의 하행 흉부대동맥까지 인조혈관으로 치환하였다. 결과: 전체 124예 중 Marfan 증후군이 동반된 경우는 18예였다.