• 센서학회지
• /
• 제13권3호
• /
• pp.230-235
• /
• 2004

This paper describes the design, fabrication and characteristics of a piezoelectric valve using MCA(Multilayer ceramic actuator). The MCA valve, which has the buckling effect, consists of three separate structures; MCA, a valve actuator die and an a seat die. The design of the actuator die was done by FEM modeling and displacement measurement, respectively. The valve seat die with 6 trenches was made, and the actuator die, which is driven to MCA under optimized conditions, was also fabricated. After Si-wafer direct bonding between the seat die and the actuator die, MCA was also anodic bonded to the seat/actuator die structure. PDMS sealing pad was fabricated to minimize a leak-rate. It was also bonded to seat die and SUS package. The MCA valve shows a flow rate of 9.13 seem at a supplied voltage of 100 V with a 50% duty cycle, maximum non-linearity was 2.24% FS and leak rate was $3.03{\times}10^{-8}pa{\codt}m^{3}/cm^{2}$. Therefore, the fabricated MCA valve is suitable for a variety of flow control equipment, a medical bio-system, automobile and air transportation industry.

• 한국가스학회지
• /
• 제18권6호
• /
• pp.27-31
• /
• 2014

본 연구에서는 LP가스 용기용 밸브에서 취약할 것으로 예상되는 Part 1, Part 2, Part 3 지역에 대한 강도안전성을 FEM으로 해석하였다. 밸브의 두께가 1.5mm이고, LPG 압력이 3.5MPa일 때 밸브의 Part 1 모서리 부분에서 27.5MPa의 Von Mises 최대응력이 걸리는 것으로 나타났다. 또한, 밸브의 두께가 1.5mm이고, LPG 압력 3.5MPa이 밸브에 작용할 때 Von Mises 최대응력은 Part 2에서 41.5MPa, 그리고 Part 3에서 46.5MPa으로 나타났다. 이러한 FEM 해석결과는 밸브의 Part 1, Part 2, Part 3에 작용하는 Von Mises 최대응력 모두가 황동소재 C3604의 항복강도 대비 9.2~15.5% 수준으로 대단히 낮은 값을 나타내고 있다. 이것은 기존의 LP가스 용기용 밸브의 두께가 지나치게 과도한 설계를 하였다는 것을 의미한다. 따라서, 밸브의 Part 1과 Part 2 지역의 두께는 황동밸브의 경량화 차원에서 얇게 설계하는 것이 바람직하다. 반면에 Part 3 지역의 두께는 기존의 밸브 두께처럼 두껍게 설계하여 높은 체결토크에도 안전한 강도를 유지하는 것이 좋다.

• 수산해양교육연구
• /
• 제28권2호
• /
• pp.350-355
• /
• 2016

This research aims to evaluated the structure improvement and new product development of valve tester. A valve tester was redesigned for structure improvement and new product development using 3-D design program CATIA. In addition, behavior analysis was conducted on the modeled valve tester using the ANSYS program. The total deformation, stress and strain were obtained by the internal pressure change. This result was applied to the new product development of valve tester.

• Journal of Chest Surgery
• /
• 제11권3호
• /
• pp.281-295
• /
• 1978

Last year in this department 100 cases of open heart surgery were done annually. This year 200 cases of open heart surgery were scheduled. During the first 6 months of this year 112 open heart surgery cases were done with 13 deaths [11.6%]. There were 72 cases of cougenital malformation with 9 operative deaths [12.5%], consisting of 23 acyanotic cases with one death [4.5%] and 49 cases of cyanotic cases with 8 deaths [16.3%]. Out of 40 tetralogy of Fallot, 6 cases expired [15%]. For 39 cases of acquired valvular heart disease and one Ebstein anomaly valves were replaced with 4 operative deaths [10%]. Single valve replacement in 33 with 3 operative deaths and double valve replacement in 7 cases with one death were noted. Two patients expired among 28 mitral valve replacement cases [7.1%]. Among 7 double valve replacement patients, consisting of 3 mitral and aortic and 4 mitral and tricuspid valve replacement one case expired. In a case of Ebstein anomaly, tricuspid valve was replaced with plication of atrialized right ventricle successfully. The operative result was excellent.

• Journal of Chest Surgery
• /
• 제25권11호
• /
• pp.1337-1345
• /
• 1992

One hundred and fourty-one Bjork-Shiley Monostrut valves were implanted in 105 consecutive patients from November 1983 to February 1990. There were 61 male and 44 female patients with a mean age of 33.6 years at the surgery. The cummurative follow-up was 370.3 patient-years with a mean of 44.0 months per patient. The operative mortality rate was 3.8%, and the linealized late mortality was 1.18%/patient-year. The incidence of major complications were 4.59%/patient-year, and the actuarial rate of freedom from valve-related morbidity was 80.2$\pm$4.4% at 7 years. The 7-year survival rate was 90.5$\pm$4.1%, and the actuarial rate of freedom from thromboembolism at 7 years was 93.3$\pm$2.3%. The linealized annual rates of complication were ; structural valve failure 0.27% /patient-year, non-structural valve failure 0.54% /patient-year, thromboembolism 1.62% /patient-year; bleeding 1.62% /patient-year; endocarditis 0.54% /patient-year. On the basis of our experience, we judged the Bjork-Shiley Monostrut valve reliable, with similar incidence of valve-related morbidity of other mechanical prosthetic valves.

• Journal of Chest Surgery
• /
• 제14권1호
• /
• pp.17-25
• /
• 1981

In 1980, 416 cases of open heart surgery were done in this Department with over all operative mortality of 12.3%. 1. There were 288 congenital anomalies consisting of 174 acyanotic and 114 cyanotic varieties, which showed operative mortality of 6.9% and 25.4% respectively. 2. There were 128 cases of acquired lesions, 124 valvular disease and 3 myxoma being the main lesions. 3. There were 128 cases of valve replacement with operative mortality of 7.8%. 4. The most frequently operated anomaly was VSD, 90 pure VSD and 21 cases were associated with one or 2 cardiac anomalies. Over all operative mortality in 111 VSD cases was 8.1% but in 90 pure VSD cases it was 6.7%. 5. Tetralogy of Fallot showed the highest incidence in cyanotic group with 88 cases, consisting of 68 pure and 20 with other cardiac anomalies. Over all mortality in 88 cases was 19.3% but in pure form 16.2%. 6. In 128 valve replacement cases over all mortality was 9.4%. There were 85 mitral, 11 aortic, 2 tricuspid, 21 mitral with aortic, 6 mitral with tricuspid, 3 mitral, aortic, and tricuspid valve replacement cases. For mitral valve replacement operative mortality was 5.9%. 7. Twenty-one cases of babies under 10kg body weight were operated on with over all operative mortality of 28.6%. Sixteen cases of VSD were found with operative mortality of 25%. 8. Among 128 cases of valve replacement 7 were under the age of 15 years and 12 were between 15 and 20 years old. Five pediatric cases underwent mitral valve replacement without mortality, 9 year old boy was the youngest among them. In this Department open heart surgery for infancy and complex anomalies showed still hip operative risk which should be improved in the coming years. For open heart surgery Shiley oxygenators and 2 sets of A-O de-lux 5 head roller pump were utilized exclusively. For valve replacement Ionescu-Shiley bovine pericardial xenografts were mainly used. In pediatric and rural patients Persantin with aspirin regimen was satisfactorily administered for anticoagulation after valve replacement. Routinely Coumadin was administered for one year after valve replacement* In patients who had thrombus on valve sites, chronic atrial fibrillation, and giant left atrium Persantin-Aspirin regimen was used when one year coumadin administration was discontinued.

• Journal of Chest Surgery
• /
• 제18권4호
• /
• pp.655-662
• /
• 1985

From January 1985 to July 1985, prosthetic heart valves were replaced in 5 patients at Keimyung University Dongsan Medical Center. The patients included three women and two men ranging in age from 22 to 41 years. Three mitral valve replacements, one aortic valve replacement and one double valve replacement [mitral and aortic valve replacement] were done at the first valve operations. Reoperation were performed 2 to 76 months after the first operations, Prosthetic valve endocarditis occurred in 3 patients, early in one and late in two and primary valve failure occurred in 2 patients. In operative findings, vegetation in prosthetic valve endocarditis and calcification in primary valve failure were found. All except one had relatively successful operative results. One died of early fungal prosthetic valve endocarditis due to relapsed prosthetic valve endocarditis with heart failure and block.

• Journal of Chest Surgery
• /
• 제16권4호
• /
• pp.602-614
• /
• 1983

Six hundred fourteen consecutive cases of bioprosthetic cardiac valve replacement performed during the period from March 1976 through December 1982 were reviewed. A total of 748 tissue valves [534 Ionescu-Shiley valves, 144 Hancock valves, 46 Angell-Shiley, and 24 Carpentier-Edwards] were implanted in 610 patients. Of these, 477 had single valve replacements [403 mitral, 60 aortic, and 14 tricuspid] including three REDO MVR and one REDO AVR. The remaining 129 had double valve replacements [95 AVR and MVR and 34 MVR and TVR] and 8 had triple valve replacement.592 cases were evaluated. Overall early mortality rate [within 30 days of operation] was 7.1% [6.2% in single valve replacement, 10.2% in double valve replacement, and 16.7% in triple valve replacement]. Leading causes of mortality were low cardiac output or myocardial failure and ventricular arrhythmias. The follow-up period was from one month to 7 years with a cumulative follow-up of 906.6 patient-years [mean 1.53 years]. The late mortality was 1.6%, 3.9%, 0%, 2.6%, 6.6% and 2.0% per patient-year for MVR, AVR, TVR or triple valve replacement, AVR+MVR, MVR+TVR and total, respectively. Actuarial analysis of late results including early mortalities indicates an expected survival rate of 87.6+1.8% at 3 years and 85.92.4% at 7 years for all cases. We also analyzed actuarial survival rate between groups of each valve replacement [AVR, TVR, Double valve, and Triple valve] and the tissue valve groups in MVR. We experienced 7 cases [0.77% per patient-year] of confirmed endocarditis, two of which were fatal. Valve failure-free rates calculated according to the confirmed cases were 97.5% at 4 years, 87.5% at 7 years, and 88.3% at 6 years for Ionescu-Shiley, Hancock and Angell-Shiley valves, respectively. The occurrence rate of thromboembolism was 2.0% per patient-year in total cases, although almost all the patients were given anticoagulant therapy for one year. The occurring rate in MVR was 1.5% and 2.7% per patient-year for Ionescu-Shiley and Hancock valve groups, respectively. The difference in actuarial rate free from thromboemboli between Ionescu-Shiley and Hancock groups was statistically significant [P value less than 0.001]. Thromboembolic events beyond the period of anticoagulation therapy mainly occurred in patients with atrial fibrillation. The actuarial thromboemboli free survival was 95.71.4% at 3 years and 80.17.3% at 7 years. The incidence of hemorrhagic complications was 1.2% per patient-year [fatality 0.55% per patient-year] for anticoagulated patients. Although our clinical data favorably compares with results from other reports, our results suggest that anticoagulant therapy be given on a short-term basis or not at all to hemodynamically stable patients. Long-term therapy with antiplatelet drugs is probably inevitable with patients who have thromboembolic risk factors [such as atrial fibrillation].

• Journal of Chest Surgery
• /
• 제37권4호
• /
• pp.328-334
• /
• 2004

삼첨판막대치술의 장기 결과에 대한 연구결과는 보고된 바가 많지 않다. 이에 저자들은 삼첨판막대치술의 위험인자를 분석해 보고, 삼첨판막대치술의 장기 결과를 알고자 연구를 시행하였다. 대상 및 방법: 대상 환자들은 1978년 10월부터 1996년 12월까지 삼첨판막대치술을 시행 받은 환자 70명을 대상으로 후향적인 연구를 진행하였는데, 7명의 환자들은 2차례의 삼첨판막대치술을 시행 받아 총 77예의 삼첨판막대치슬을 시행하였다. 환자들의 평균 나이는 38.8$\pm$15.9세였으며, 26예에서는 조직판막을, 51예에서는 기계판막을 이식하였다. 결과: 수술 사망률은 15.6%였고, 만기 사망률은 12.3%였다. 5년, 10년 그리고 13년에서의 생존율은 조직판막과 기계판막이 각각 81.3% vs. 100%, 66.1% vs. 100%, 60.6% vs. 100%였다(p=0.0175).판막과 관련된 재수술이 없을 확률은 5년, 10년 그리고 13년에서 조직판막과 기계판막이 각각 100% vs. 93.9, 100% vs. 93.9% 그리고 58.3% vs. 93.9%였다(p=0,3274). 판막과 관련된 재수술을 시행할 확률은 조직판막이 2.27%/환자-년이었고, 기계판막이 1.10%/환자-년이었다. 수술 사망과 관련된 위험인자 분석상, 수술 전 복수, 간비대, NYHA class가 나쁠수록, 그리고 삼첨판막대치술을 여러 번 받는 경우가 유의한 위험인자로 분석되었고, 조직판막의 사용과 심장수술을 여러 번 받는 경우가 만기 사망과 관련된 유의한 위험인자로 분석되었다. 걸론: 기계판막을 이용하여 삼첨판막대치술을 시행한 환자들의 장기간 생존율이 조직판막을 이용한 환자들보다 우수하였다. 따라서 수술 후에 적절한 추적관찰이 가능하다면, 기계판막을 이용하여 삼첨판막대치술을 시행하는 것이 필요하리라 생각한다.

• 한국수소및신에너지학회논문집
• /
• 제11권3호
• /
• pp.107-117
• /
• 2000

Ball poppet valve type high pressure hydrogen injection valve actuated by solenoid has been developed for the feasibility of practical use of hydrogen fueled engine with direct injection and the precise control of fuel injection ratio in hydrogen fueled engine with dual injection. The gas-tightness of ball poppet injection valve is improved by the introduction of ball-shaped valve face, valve end typed spherical pair, and valve stem with rotating blade. Ball poppet valve is mainly closed by differential pressure due to the area difference between valve fillet and pressure piston. So, it can be operated by solenoid actuator with small driving force. From the evaluation of ball poppet injection valve, it was found that the gastightness and controlment of this injection valve are better than those of injection valve had been developed before.