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김진범(Jin-Bum Kim),권기영(Ki-Yeoung Kweon),이학성(Hahk-Sung Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
High-voltage auto-expansion circuit breakers utilize the ablation of polytetrafluoroethylene(PTFE) nozzle to produce adequate conditions for arc quenching at current zero. The high-current simulation provides information about the mixing process of the hot PTFE cloud with the SF? gas which is difficult to access for measurement. But it is also difficult to simulate flow phenomenon because the flow in interrupter with high current and SF?-PTFE mixture vapor, complex physical behavior including radiation. Using the PC based PHOENICS, a commercial computational fluid dynamics(CFD) package, the conservation equation for the gas and temperature, velocity and electric fields within breaker can be visualized and thermal interruption capability predicted. These numerical results will reduce the number of costly short-circuit test.
조진범(Jin Bum Cho),조항주(Hang Joo Cho),신옥란(Ok Ran Shin),김기환(Kee Hawn Kim),안창혁(Chang Hyeok Ahn),김정수(Jeong Soo Kim),유승진(Seung Jin Yoo),임근우(Keun Woo Lim),김지일(Ji Il Kim) 대한외과학회 2008 Annals of Surgical Treatment and Research(ASRT) Vol.74 No.6
Purpose: A mucocele of the appendix is an uncommon pathology, representing 0.2% to 0.3% of all appendix specimens. It is often diagnosed clinically as a result of its ability to cause signs and symptoms similar to those of acute appendicitis. If it is asymptomatic, it is often detected as an incidental finding during ultrasonography, computed tomography, radiographic examination of the gastrointestinal tract, or laparotomy. The purpose of this study was to identify the clinical features of mucocele of the appendix. Methods: We describe 35 cases of mucocele of the appendix diagnosed at Uijeongbu St. Mary’s hospital between January 1993 and December 2006. We analyzed demographic, clinical, and pathologic data of all the cases. Results: A total of 12 males and 13 females with mean age of 54.7±14.9 years are described. The peak incidence occurred in the seventh decade (34.3%). Sixteen patients presented with symptoms and signs similar to those found in acute appendicitis. Ten patients complained of a palpable mass, 2 patients complained of non-specific abdominal pain, and 7 patients were asymptomatic. Fourteen cases were diagnosed preoperatively, and 3 cases were discovered incidentally. Pathologic examination revealed mucosal hyperplasia in 20% of the cases, cystadenoma in 71%, and cystadenocarcinoma in 9%. The mean age of cystadenocarcinoma patients was older than the mean age of mucosal hyperplasia patients, and the diameter of the appendix was larger in cystadenoma patients than in mucosal hyperplasia patients. Conclusion: The preoperative diagnosis of appendiceal mucocele is very important to make in order to facilitate treatment planning and avoid inadvertent rupture of the mucocele during operation. We recommend more diagnostic studies in cases of suspected mucocele. Mucocele of the appendix must be included in the differential diagnosis of patients with pain in the right iliac fossa, patients older than 40 years of age, patients suffering from long-term symptoms, and patient with a palpable mass in the right iliac fossa.
PTFE 용삭을 고려한 초고압 복합소호 차단기의 열챔버 압력 특성 평가
김진범(Jin-Bum Kim),권기영(Ki-Yeoung Kweon),이학성(Hahk-Sung Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. During the arcing period, high pressure, temperature and radiation of the arc could burn in pure SF6 gas and PTFE nozzle. Ablated nozzle shape and SF6-PTFE mixture vapor affect the performance of an self-blast circuit breaker. But it is hard to simulate the behavior of hot gas, prediction because of complex physical behavior including radiation, calculation of electric field. Using computational fluid dynamics, the conservation equation for the gas and temperature, velocity and electric fields within breaker can be solved. Performance of ablated nozzle shape are compared with original model.