http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
New Aggregation Algorithm for Tandem queue with Finite Buffers
김종환,Hur, Sung Kwan,徐承祿 大邱大學校附設 基礎科學硏究所 1991 基礎科學硏究 Vol.8 No.-
We consider a two-stage fmite tandem queueing system with Poisson arrivals and negative exponential service times. The customer who has completed his service at the first station has to go directlty to the second station. If the queue of the second station is full at the moment of the service completion of the customer at the first station, then the customer receives, another service at the first station. This is repeated until the customer completes a service at the first station at the moment that the second station is not fulL The problem of calculating the steady-state probabilities of this queueing system by the ordinary balance equations is time consuming. We develop an efficient algorithm to obtain the steady-state probabilities that utilize the two-way state aggregation techniques.
김종환,홍재승 한국스포츠산업경영학회 2003 한국스포츠산업경영학회지 Vol.8 No.2
프로축구리그관중의 만족도와 재구매의도의 상관요인분석에 관한 연구김종환 (중앙대학교), 홍재승 (서울대학교)
김종환 대한흉부심장혈관외과학회 1987 Journal of Chest Surgery (J Chest Surg) Vol.20 No.2
A total and consecutive 163 patients underwent cardiac valve replacement using the Hancock porcine xenograft cardiac valves from 1 976 to 1984. Of 198 substitute valves, 177 were the Hancock valves. One hundred twenty-nine patients[79.1%] had single valve replacement: MVR 118, AVR 8 and TVR 3; 33[20.3%] had double valve replacement: MVR+AVR 27 and MVR+TVR 6; and a single case had triple valve replacement. Other surgical procedures were added in 34 patients. The operative mortality rate within 30 days of surgery was 6.1%, and it was, however, 4.2%, with single MVR. Late mortality rate was 6.7% or 1.95%/patient-year of a linealized mortality rate. Early survivors of 153 patients were followed up for a total of 565.1 patient-years [a mean of 44.3*27.1 months]. The linealized annual complication rates were: 1.95% emboli/patient-year, 0.89% bleeding/patient-year 1.24% endocarditis/patient-year, and 4.25% overall failure/patient-year. Primary tissue failure occurred at a rate of 1.59%/patient-year. The actuarial survival rates including operative mortality were 87.0*4.1% and 77.3*6.6% at 5 and 11 years after surgery respectively. The probability of freedom from thromboembolic complication of 89.2*3.4% at 5 years after surgery lasted unchanged upto 11 years. The probability of freedom from overall valve failure was 81.3*4.5% at postoperative 5 years, and it dropped down to 26.2*19.4% at 11 years, although the latter was statistically insignificant because of a small number of patients entering into the years approaching the follow-up end. However, the probability of freedom from the primary tissue failure was 81.3*10.6% at postoperative 9 years, which coincides closely with the speculated rate of tissue degeneration of about 20% in 10 years. These clinical results confirm the low thrombogenicity of the Hancock porcine valve and the reasonable failure rate of tissue degeneration.
김종환 대한흉부심장혈관외과학회 1989 Journal of Chest Surgery (J Chest Surg) Vol.22 No.2
A total and consecutive 291 patients of isolated single mitral valve replacement using the Ionescu-Shiley bovine pericardial xenograft valve operated on between October 1978 and June 1983 were retrospectively studied for the durability of the substitute valves based on the structural degeneration of primary tissue failure which had been proved on their re-replacement surgery. The mean age at the initial surgery was 32.4*12.5 years, and the operative mortality rate was 5.2 %. The early survivors of 276 patients were followed up for a total 1148.3 patient-years[mean\ulcornerD, 4.16*2.57 years]at the follow-up end of June 1988. They experienced 4 major late complications: 1.045 % thromboembolism/patient-year [pt-yr]; 0.871 % bleeding/pt-yr; 0.610% endocarditis/pt-yr; and 3.309% overall valve failure/pt-yr or 1.655% primary tissue failure/pt-yr. The actuarial survival rates were 89.4*2.2% and 87.7*2.5% at 5 and 10 years after initial surgery respectively. The probabilities of freedom from thromboembolism were 95.1*1.6% and 93.2*2.0% at 5 and 10 years after surgery. Nineteen patients underwent re-replacement of the Ionescu-Shiley valve because of primary tissue failure, and there was no operative mortality. The incidence of primary tissue failure was highest for the patients less than 15 years of age occurring in 9 out of 27 patients [33.3 %] or 8.68 %/pt-yr, while it was 4.0 % or 0.96 %/pt-yr for the rest of patients older than this age. The probabilities of freedom from primary tissue failure were 96.7*1.4 % and 84.2*3.8% at 5 and 9 years after surgery. The freedom from tissue failure increased as the age limits of cumulative younger patients were increased while it decreased as the age limits of cumulative older patients were decreased. Although it is clear that the Ionescu-Shiley valve would degenerate prematurely in young patients, the definite age limit could not be identified when the risk of early failure was significantly high.