• Journal of Advanced Marine Engineering and Technology
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• 제35권3호
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• pp.317-322
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• 2011

This work has investigated the exhaust emissions such as Total Hydrocarbon (THC), Nitrogen Oxides(NOx), and Particulate Matter (PM) characteristics emitted from the tail-pipe of a continuously variable valve timing (CVVT) gasoline-fueled engine with different intake valve opening timings and injection pressures at the part load condition. Valve overlap period was varied from $40^{\circ}CA$ to $10^{\circ}CA$ and fuel injection pressure was increased from 3.5 bar to 5.0 bar. THC and NOx emissions decreased as intake valve opening timing was advanced regardless of fuel injection pressure. When the fuel was injected with the condition of 5.0 bar at all of valve overlap ranges, THC levels were reduced by 55%. NOx concentrations were diminished about 75% as valve overlap increased. PM size distributions were analyzed as bi-modal type of the nucleation and accumulation mode. Comparing with fuel injection pressures, PM emission levels were decreased at high pressure injection of 5.0 bar condition.

• Journal of Chest Surgery
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• 제26권3호
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• pp.191-195
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• 1993

Among 25 consecutive cases having undergone mitral valve surgery between March 1991 and June 1992 in Gill General Hospital, 11 patients[44%] who had undergone mitral valve reconstruction using prosthetic rings is evaluated and presented. Patients` mean age is 43 + 19 years[range:16-72], and they are consisted with 4 males and 7 females. Mitral valve insufficiency is due to degenerative disease in 6 cases[55%] and rheumatic disease in 5 patients[45%]. Carpentier`s functional classification I is 2 cases, II is 6 cases, and III is 2 cases. Surgical techniques include prosthetic ring annuloplasty[11 patients, 100%], chorda shortening[6, 55%], leaflet mobilization[4,36%], new chorda formation[2, 18%], chorda transposition[1, 9%] commissurotomy[3, 27%], and papillary muscle splitting[3, 27%]. Average number of mitral anatomic lesions per patient are 2.7 and we used average 2.8 procedures upon mitral valve apparatus per patient. There were no surgical mortality and no late valve related admission during the mean follow up period of 17 months. The mean functional class[NYHA] is 2.81 preoperatively and improved to 1.10 postoperatively. Doppler echocardiography showed much improvement from grade II MR [1 case], grade III MR [1 case] and 9 cases of grade IV MR to 6 cases of patients showed no MR, only trace MR in 4 cases, and grade I MR was found only in one patient with NYHA functional class II postoperatively. The postoperative mean mitral valve area is $2.10+0.28cm^2$. We conclude that mitral reconstruction is a predictable and stable operation.

• 한국기계가공학회지
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• 제13권3호
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• pp.49-55
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• 2014

This paper examines the effects of spring characteristics and stiffness in relation to the characteristics of hydrodynamic force. Spring forces and stiffness determine the performance of this type of pan check valve and have an effect on the overall operation. The hydraulic efficiency of the pan check valve is relatively low compared to that of a common check valve. However, a pan check valve is structurally more stable than a common check valve. We implemented the optimum design to increase the flow rate and to resolve the suppression of the pressure drop according to the extent of the compression of the spring. From the results of a flow analysis, we demonstrate spring stiffness design criteria depending on the extent of the compression of the spring of pan check valve acting on the fluid at the inlet 1 MPa pressure.

• 한국생산제조학회지
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• 제24권3호
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• pp.263-269
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• 2015

Growing concerns regarding air pollution have recently increased the demand for liquefied natural gas (LNG) fueled ships. LNG-fueled ships are equipped with an explosion relief valve in the crankcase to relieve excessive pressure and stop flames from emitting from the crankcase. In this study, a finite element analysis was conducted to evaluate the crankcase relief valve disk spring design using an ANSYS Workbench, v.15. The setting pressure, leak and explosion test performed by european standard EN14797 to evaluate function and mechanical integrity of crankcase relief valve. The tests results indicate that the pressure of the crankcase relief valve is 3.05 bar, with no air leakage at 2.97 bar. Finally, the mechanical integrity of the crankcase relief valve was confirmed through an explosion test in which the valve plate assembly, flame arrester, and other parts were safe from fracturing.

• Journal of Chest Surgery
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• 제33권8호
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• pp.643-647
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• 2000

From March 1988 to June 1994, 275 CarboMedics cardiac valve prostheses(199 mitral, 70 aortic and 3 tricuspid) were implanted in 226 consecutive patients(mean age 39 years, male/female 90/136) by one surgical team operating on adult cardiac patients at Kyungpook University Hospital. Total follow up represented 16,848 patient-months(mean 76 months) and follow up rate was 96%. One hundred and forty-nine patients(66%) wer in NYHA functional class III or IV preoperatively, and 204 patients(99.5%) were in class I or II postoperatively. Early mortality was 4.9% and late death was 9.3%. The actuarial survival at 81 months was 86.l2$\pm$3.1%. The linearized incidence of valve-related death, prosthetic valve thrombosis, anticoagulation-related hemorrhage, non-structural dysfunction and reoperation were 0.71%, 0.43%, 0.07%, 0.21%, and 0.14% respectively. The 81-month rate of freedom from all valve related complications and deaths including hospital mortality was 88.1$\pm$2.5%. Thee facts suggest that the CarboMedics cardiac valve has excellent result, low incidence of valve-related complications and no structureal deterioration.

• 전기학회논문지P
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• 제55권3호
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• pp.123-127
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• 2006

In a heating control system, the indoor temperature controller transfers temperature signals inputted from the temperature sensor and the user to the valve controller. The valve controller receives these signals then the valve controller controls the valve driving motor on two position control and controls the indoor temperature. When setting up a new valve driving motor from a long distance it is necessary to set up a new valve controller. But occasionary, due to construction, It is impossible to wire between the existing valve controller and the new valve controller. In this situation, the new and existing valve controllers can communicate via power line communication. In this paper it is proposed heating control system controls on two position control via power line communication.

• Journal of Chest Surgery
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• 제17권1호
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• pp.3-11
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• 1984

Prosthetic valve replacement has resulted in marked improvement in the functional status of many patients with valvular heart disease. But valve failure from various causes has necessitated re-replacement of prosthetic valve in some of these patients. This selective group of patients has many inherent problems. This report presents our experience with seven patients who received re-replacement of prosthetic valve in the Seoul National University Hospital from 1981, to 1983. The patients included one woman and six men in the range of 9 and 49 years old. As the first valve operations, there were five MVR using tissue valves, one DVR [Bjork-Shiley and Ionescu-Shiley valve] and one case of modified Bentall operation with composite graft [Ionescu-Shiley valve]. Reoperations on prosthetic valve failure were performed 17 to 54 months after the first operation [mean 34 months]. Amon8 seven patients, there were two cases of prosthetic valve endocarditis and five cases of primary tissue failure. Gross calcification of the xenograft was found in two children with Ionescu-Shiley valve. All except one had relatively successful operative results. The unsuccessful one died intraoperatively from low output syndrome.

• Journal of Chest Surgery
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• 제28권9호
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• pp.817-821
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• 1995

The CarboMedics Medical valve has become our mechanical valvular prosthesis of choice because of favorable hemodynamic results that associated with marked clinical improvement and low incidence of thromboembolism after it,s uses. The data for this study was collected from August 1988 to July 1993,five years period. There were total of 57 patients[female 40,male 17 in this series with 4 isolated aortic valve,26 isolated mitral valve,11 double valve and a triple valve replacement. The mean follow up time was 32 months. Postoperatively,58% of cases were in New York Heart Association[NYHA functional class I,and mild and moderate symptoms[NYHA class II were present in 36% and there were very few patients remaining in higher functional classes. In postoperative echocardiographic study, showed marked improved cardiac function. The overall early mortality was 3.5% and the late mortality was one case after triple valve replacement due to sudden death. The causes of early death were attributed to early prosthetic valve endocarditis and heart failure.

• 보험의학회지
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• 제32권2호
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• pp.28-32
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• 2013

We studied trends of cardiac valve surgery using insurance data. 368 persons were included our study. We studied whether there are frauds or not. Only 4 cases were done at less than 1year from an insurance contract. We reviewed medical records of all persons. We could find the type of valve disease in 211 cases. The findings are atrial valve 40.1%, mitral valve 34.6% and others 25.3%. When we divided by materials of surgery, mechanical valves were used in 68.8% of men and 70.6% of woman. The main causes of valve disease were infection(55.1%). And degenerative valve disease 32% and congenital valve disease were 13%. We cannot find definite evidence of insurance frauds in the cardiac valve surgery. But there are some limitation in data analysis.

• Journal of Chest Surgery
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• 제27권12호
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• pp.984-988
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• 1994

Between 1981 and 1992, 22 children from 1 to 15 years of age have undergone cardiac valve replacements at National medical center. The patients were composed of 14 males and 8 females and 7 patients had congenital heart disease and 15 patients had rheumatic heart disease. Three of these 15 patients have had second valve replacement due to prosthetic valve failure[PVF]. Single valve replacement were 20[Aortic 3 cases, Mitral 17 cases] and double valve replacments were 2. The overall mortality was 22.7 %. Actuarial survival rate was 77.28 $\pm$ 8.92 % and Complication free rate was 67.68$\pm$15.56%. The pediatric valve replacements can now be performed at a low operative risk although various problems are still remained and the choice of valve is prosthetic valve mainly due to its durability at the present time.