• 대한기계학회논문집B
• /
• 제23권2호
• /
• pp.281-287
• /
• 1999

The turbulent natural convection in the membrane type LNG carrier cofferdam with heating points has been studied by numerical method. As the numerical methods, we introduced the three turbulence model, a standard $k-{\varepsilon}$ model and two case of a low Reynolds number models. The parameters considered for this study ore number and capacity of heating points i.e., $1{\leq}Ns{\leq}12$ and $1.0{\times}10^5{\leq}Qs(W/m^3){\leq}1.0{\times}10^8$. The results of the isotherms and velocity vectors have been represented for various parameters. The temperature and velocity at upper position in the space ore shown to be higher than those at lower position. For obtaining the optimal temperatures, $20{\sim}30^{\circ}C$ in the cofferdam space, the heating capacities show $2.0{\times}10^7W/m^3$ at g-heating points and $1.0{\times}10^7W/m^3$ at 12-points. The mean temperature in the cofferdam space can be expressed as a function of number and capacity of heating points.

• The Journal of Asian Finance, Economics and Business
• /
• 제7권5호
• /
• pp.185-194
• /
• 2020

The study aims to identify and measure factors affecting the perception of the selling price of luxury apartments in Hanoi. We conducted a questionnaire consisting of 29 observation variables with a 5-point Likert scale. Independent variables were measured from 1 "without effect" to 5 "strongly". Based on the desk review and results of interviews, a total of 500 questionnaires were sent to research participants for collection; 458 of them met standard and were subject to be analyzed. This study employs Cronbach's Alpha test, and regression model. The results of Exploratory Factor Analysis (EFA) and Multiple Regression Analysis (MRA) identify five main determinants influencing the perception of the selling price of luxury apartments in Hanoi, including Physical characteristics of a luxury apartment (PC); Location and position of an apartment (LP); Surrounding Area (SA); Quality of service provided by managers; (QS) and Demographics factor (DF). Based on the findings, some recommendations have been proposed to help the firm leaders design appropriate personnel policies for creating better price satisfaction for customers in the future. On this basis, the authors propose a number of recommendations to improve the quality of luxury apartments, thereby contributing to the development of the market for luxury apartments in Hanoi.

• Journal of Chest Surgery
• /
• 제25권12호
• /
• pp.1563-1569
• /
• 1992

From Jan. 1981 to Dec. 1991, we had treated 25 patients with congenital coronary art-eriovenous fistulas [CAVF] in Seoul National University Hospital. A retrospective review was made to delineate the course and the management of CAVF and to clarify the role of surgical treatment. Fifteen patients were male and 10 were female with The mean age of 17.4 years[from 3 months to 58 years]. The most frequent symptom was dyspnea on exertion[56%]. Other symptoms were angina and palpitation. Sixty-eight percent of the patients were symptomatic. Fifty-three percent of patients less than 20 years old were symptomatic and 100% of patients over 20 years old were symptomatic. Three patients had multiple CAVFs. The fistula drained into the right ventricle in 13, pulmonary artery in 9, left ventricle in 4, right atrium in 2, and left atrium in 1. Thirteen patients had other associated cardiac lesions. The mean pulmonary-to-systemic blood flow[Qp /Qs] in the isolate CAVF group was 2.19. All patients were operated on to correct the fistulas and other associated cardiac lesions. All patients were followed from 1 month to 11 years without late death. Postoperative complication rate was 24% -significant arrhythmia [3], recurred CAVF[1], psychosis[1], pneumonia [1]. Symptomatic improvement was evident postoperatively. Below 20 years old, 94% of patients were asymptomatic, but above 20 years old, symptoms persisted in 25%. In summary, early elective repair of CAVF is indicated in all patients because of higher complication rate and frequent persistent symptoms in older patients.

• Journal of Chest Surgery
• /
• 제19권4호
• /
• pp.627-632
• /
• 1986

This report describes our 17-years experience with intracardiac repair in 123 patients older than 15 years with tetralogy of Fallot. Major clinical manifestation was cyanosis and clubbing [102 Pts], but other minor associated manifestation were infective endocarditis, pulmonary tuberculosis, brain abscess, congestive heart failure, nephrotic syndrome, and tuberculous spondylitis. Prior palliative shunts had been performed in 10 patients. Preoperative hemoglobin ranged from 9.7 gm/dl to 25 gm/dl [mean 19 gm/dl]. The type of ventricular septal defect were typical perimembranous type, and total canal defect [13%]. The right ventricular outflow tract obstruction was due to combined [58.5%], infundibular [35%], and valvular stenosis [6.5%]. Transannular patch was used in 17% of patients. Hospital mortality was 9.8% in overall, but decreased to 1.7% since 1982. There was two late death [12 year actuarial survival [97%] due to fulminant hepatitis, residual abnormalities [PS, VSD]. Ninety two percent of survivors at follow-up are asymptomatic and leading an active normal life. Residual ventricular septal defect was detected with radionuclide single pass study in 15.3% of patients but almost cases were Qp/Qs less than 1.5, and only two patients had been candidates for reoperation.

• Journal of Chest Surgery
• /
• 제24권1호
• /
• pp.1-7
• /
• 1991

This report describes our 10-year experience with intracardiac repair in 42 patients older than 16 year with tetralogy of Fallot. The mean age was 22.0$\pm$5.18 years[range 16~41]. The preoperative clinical manifestations were cyanosis & clubbing[93%], frequent URI [55%], anoxic spell[40%], pulmonary tuberculosis[21%], tuberculous empyema[7%], chronic renal failure[7%], congestive heart failure[7%] and subacute bacterial endocarditis [2%], etc. The previous shunt procedure for palliation had been performed in 7 patients. The type of VSD were typical perimembranous type[67%], total canal defect[28%] and combined type[5%]. The right ventricular outflow tract obstruction were combined type[69%], infundibular type[21%] and valvular type[10%]. Transannular patch was used in 50% of patients. Associated cardiovascular anomalies were ASD[33%], PFO[31%], Rt. aortic arch[10%], Lt. SVC[10%], single Rt. pulmonary artery, single Lt. coronary artery, ASI, proximal stenosis of Rt. pulmonary artery and anomalous systemic venous return, etc. Hospital mortality was 7.1%[3 cases]in overall. The causes of hospital deaths were revealed low cardiac output & acute renal failure[2 cases], postoperative bleeding[1 case]. There were 2 late deaths 3 & 68 months after surgery. Residual intracardiac shunt was detected in 2 patients. one patient was successfully reoperated and another patient had Qp /Qs ratio less than 1.5.

• Journal of Chest Surgery
• /
• 제22권2호
• /
• pp.234-245
• /
• 1989

Between January 1984 and December 1986, sixty nine patients, aged 16 months to 25 years [mean age 10.05*6.40 years], underwent total correction of tetralogy of Fallot in Kyungpook national university hospital. In 66 hospital survivors, 30 patients were followed up for 12 to 48 months [mean 30.10*10.26 months]. These 30 patients were classified in two groups, TAP [transannular patch] and Non-TAP group. There were 9 patients in TAP group, and 21 in Non-TAP group. There were no significant differences between two groups in terms of age at operation, follow up duration, ACC time, and bypass time. All patients were evaluated by two dimensional echocardiography, Doppler echocardiography, standard 12-lead electrocardiography, and plain chest X-ray. Right ventricular systolic pressure, pulmonary arterial systolic pressure, pressure gradient between the right ventricle and the pulmonary artery, presence or absence of pulmonary regurgitation and its grading, fractional shortening of the left ventricle, and Qp/Qs in case of remnant ventricular septal defect were obtained by echocardiographic examination. Cardiothoracic ratio was measured by plain chest film, and ventricular dysrrhythmia was detected by electrocardiogram. Comparing the data between two groups, there was significant difference in incidence of postoperative pulmonary regurgitation [p< 0.05], 100%[9/9] in TAP group and 47.6 %[10/21] in Non-TAP group, but all the regurgitations were not severe. There were no significant differences in other comparisons, despite of higher incidence of cardiomegaly in TAP group [CT ratio: 59.3*5.3% VS 54.7*6, 4 %].

• Journal of Chest Surgery
• /
• 제28권1호
• /
• pp.18-22
• /
• 1995

From January 1989 to December 1993, cardiac catheterization and open heart surgery for ventricular septal defect closure were performed in 115 pediatric patients who were selected as meeting the criteria for elective closure of restrictive ventricular septal defect. These criteria included age greater than 1 year and less than 15 years, no evidence of congestive heart failure, Qp/Qs 2.0, pulmonary artery systolic pressure 35mmHg, and no associated cardiac anomalies. Mean age of patients was 5.25$\pm$ 3.53, and 72 patients were male, 43 patients were female[male:female=1.9:1 . Mean systolic pulmonary artery pressure was 19.66$\pm$4.79mmHg, and mean pulmonary to systemic flow ratio was 1.27$\pm$ 0.28. Aortic cusp prolapse was present in 30 patients [26% , aortic insufficiency was present in 1 paient, and 1 patient had prior bacterial endocarditis. There were no instances of complete atrioventricular dissociation, reoperations for bleeding, or reoperations for recurrent ventricular septal defect, but wound infection was present in 1 patient, and there were 7 patients who had the hemodynamically insignificant remnant shunt. There were no early or late deaths or major morbidity.

• 한국통신학회논문지
• /
• 제33권11C호
• /
• pp.874-879
• /
• 2008

[1]에서 LCZ 수열군의 2배 확장을 제안하였다. 본 논문에서는 [1]에서의 2배 확장방법을 일반화하는 새로운 확장방법을 제안한다. 이 생성방법을 사용하면 인수가 (N,M,L,${\epsilon}$)인 q진 LCZ 수열군은 인수가 (pN,pM,p[(L+1)/p]-1,p${\epsilon}$)인 q진 LCZ 수열군이 된다. 이 때, p는 소수이고 p는 q의 약수다. 특히 L${\equiv}$p-1modp일 때, 확장된 q진 LCZ 수열군의 인수는 (pN,pM,L,p${\epsilon}$)이 된다.

• 제어로봇시스템학회논문지
• /
• 제12권5호
• /
• pp.411-418
• /
• 2006

There are mainly two types of bang-bang controllers for nominal linear time-invariant (LTI) system. Optimal bang-bang controller is designed based on optimal control theory and suboptimal bang-bang controller is obtained by using Lyapunov stability condition. In this paper, the suboptimal bang-bang control method is extended to LTI system involving both control input saturation and structured real parameter uncertainties by using Lyapunov robust stability condition. Two robust optimal bang-bang controllers are derived by minimizing the time derivative of Lyapunov function subjected to the limit of control input. The one is developed based on the classical quadratic stability(QS), and the other is developed based on the affine quadratic stability(AQS). And characteristics of the two controllers are compared. Especially, bounds of parameter uncertainties which theoretically guarantee robust stability of the two controllers are compared quantitatively for 1DOF vibrating system. Moreover, the validity of robust optimal bang-bang controller based on the AQS is shown through numerical simulations for this system.

• 전자공학회논문지S
• /
• 제36S권9호
• /
• pp.18-26
• /
• 1999

여러쓰는이 검파는 간섭과 근원 효과 문제를 해결할 수 있기 때문에 널리 연구되고 있다. 이 논문에서는 유사동기 채널에서 안테나 배열을 쓰는 역방향 연결 시스템에서의 유사최대비슷함 검파기를 생각하였다. 제안한 시스템은 다른 쓰는이들의 정보를 모두 알지 않더라고 쓰는이 사이 간섭을 줄일 수 있음과 이제까지의 정합 여파기보다 성능이 더 뛰어남을 보였다.