• 소음진동
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• 제6권6호
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• pp.749-754
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• 1996

In this paper, a design method of matching layers is presented for the sandwich type broad band underwater acoustic vibrators. The characteristic impedances of matching layers are determined to be matched to the characteristic impedance of head mass material. For the dynamic characteristic analysis of the sandwich type transducers, one dimensional FEM technique is also introduced. A test vibrator with the quarter wave matching layers has been designed to verify the proposed method. And the wide band characteristics of the input impedance and transmitting voltage response (TVR) are investigated.

• Journal of Chest Surgery
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• 제20권2호
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• pp.281-288
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• 1987

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.

• 한국음향학회지
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• 제30권6호
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• pp.344-352
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• 2011

본 논문에서는 후면추가 탄성체에 의해 고정된 Tonpilz 트랜스듀서의 공진 특성을 등가회로를 이용하여 연구하였다. 후면추가 고정됨으로 인해 발생하는 추가적인 공진특성을 나타낼 수 있는 등가회로를 설계하였으며, 설계된 등가회로를 이용하여 얻은 송신음압감도 (TVR)를 유한요소해석을 통해 도출한 결과와 비교하여 그 타당성을 검증하였다. 등가회로를 이용하여 송신특성을 파악한 결과, 유한요소해석 결과와 일치하였으며, 후면추 고정재료의 강성과 후면추의 질량 변화에 따른 공진 주파수와 송신음압감도 변화를 명확히 파악할 수 있었다. 본 연구에서 도출한 등가회로를 이용하면 설계변수의 변화에 따라 모델을 변경해야하고 긴 계산시간이 요구되는 유한요소해석에 비해 효과적으로 트랜스듀서의 공진특성을 해석할 수 있다.

• 한국연초학회지
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• 제16권1호
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• pp.3-13
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• 1994

To minimize the time ordinarily spent in mono filter cigarette design, we studied the relationship between major seven independant variables ; filament(X1) and total denier(X2), porosity of the aller plug wrap(X3), filter length(X4), Porosity of the tip paper(X5) and cigarette paper(X6) and net weight of the reference cut tobacco(X7). Ninty trial numbers were obtained as a results of using rotatable central composite design and it is analyzed by the multiple regression analysis with stepwise in SAS/pc under restricted conditions. That is, UPD (Y1) = 82.96 - 3.80X1 + 2.50X2 - 3.29X3 - 3.15X5 - 0.83X22 + 1.88X5X6 - 1.38 X5X7(R2: 0.63), EPD(Y2) : 120.91 - 5.70X1 + 3.60X2 + 4.23X4 - 0.93X6 + 4.06X7 (R2=0.84), TVR(Y3) = 49.70 - 0.78X1 + 3.60X3 + 2.00X4 + 4.20X5 - 0.93X6 + 2.64X7 - 1.07X1X2 + 1.0IX1 X3 + 1.05X2X6 + 0.45X22 - 0.64X42 + 1.29X4X6 - 0.97X4X7 - 1.28X5X6 + 1.53X5X7 + 1.39X6X7(R2=0.65), and EVR(Y4) : 3.24-0.21X3-0.20X4 -0.24X5+0.67X6+0.26X4X7 (R2=0.55), where EPD : encapsulated pressure drop, VPD : unencapsulated pressure drop, TVR ; tip ventilation rate, and En : envelope ventilation rate. All variables in the model are significant at the 0.05 level.

• 수산해양기술연구
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• 제46권2호
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• pp.173-183
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• 2010

In a split beam echo sounder, the transducer design needs to have minimal side lobes because the angular position and level of the side lobes establishes the usable signal level and phase angle limits for determining target strength. In order to suppress effectively the generation of unwanted side lobes in the directivity pattern of split beam transducer, the spacing and size of the transducer elements need to be controlled less than half of a wavelength. With this purpose, a 50 kHz tonpilz type transducer with a half-wavelength diameter in relation to the development of a split beam transducer was designed using the equivalent circuit model, and the underwater performance characteristics were measured and analyzed. From the in-air and in-water impedance responses, the measured value of the electro-acoustic conversion efficiency for the designed transducer was 51.6%. A maximum transmitting voltage response (TVR) value of 172.25dB re $1{\mu}Pa/V$ at 1m was achieved at 52.92kHz with a specially designed matching network and the quality factor was 10.3 with the transmitting bandwidth of 5.14kHz. A maximum receiving sensitivity (SRT) of -183.57dB re $1V/{\mu}Pa$ was measured at 51.45kHz and the receiving bandwidth at -3dB was 1.71kHz. These results suggest that the designed tonpilz type transducer can be effectively used in the development of a split beam transducer for a 50kHz fish sizing echo sounder.

• Journal of Chest Surgery
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• 제24권4호
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• pp.382-389
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• 1991

The clinical observations on the 63 cases of the mitral valvular heart disease treated in the department of Thoracic and Cardiovascular Surgery, Kosin medical college, during the period of 5 years from January, 1986 to December, 1989, are as follows. 1. Total 63 cases, 23 were male and 40 were female with sex ratio of 1: 1.7. 2. The age distribution was widely varied from 7 years of the youngest to 65 years oldest, average age was 35.3 year old. 3. The main clinical symptom and sign were D.O.E, general weakness, fatigability, palpitation, chest pain, hepatomegaly, pitting edema and both neck vein distension. 4. The preoperative N.Y.H.A functional classification were class II, III, IV in 28%, 54%, 16%. 5. The preoperative diagnosis were MS - 6.3%, MR - 53.9%, MSR - 36.5%, MVP - 3.1%. 6. All 63 patients were operated on the under direct vision using extracorporeal circulation, MVR in 18 cases, MVR and Tricuspid annuloplasty in 24 cases, DVR in 3 cases, DVR and Tricuspid annuloplasty in 5 cases, TVR in 1 case, Mitral annuloplasty in 4 cases, mitral valvuloplasty in 7 cases and mitral commissurotomy in 2 cases 7. The operative mortality was 7.9%, and 5 years actuarial survival rate was 89%.

• 한국전기전자재료학회논문지
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• 제29권9호
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• pp.532-538
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• 2016

In this paper, a underwater acoustic Tonpilz transducer with the piezoelectric single crystal(72PMN-28PT) is developed. The thickness and the number of piezoelectric elements are theoretically designed with the equivalent circuit analysis to have the desired resonance frequency. In order to compare the performances, a piezoelectric ceramic transducer is also manufactured and their electrical impedance, TVR (transmitting voltage response), RVS (receiving voltage response) and beam pattern are compared.

• Journal of Chest Surgery
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• 제22권5호
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• pp.748-752
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• 1989

We experienced 6 patients with the sinus Valsalva aneurysm rupture during last 12 years [Jan. 1977-Sep. 1989]. Of them. 5 cases were reviewed. They consist of 3 males and 2 females, and the age ranged from 12 years to 40 years with the mean age of 25 years. 4 patients showed congestive heart failure symptoms. The diagnosis was made by 2D-Echo and cine-angiogram. In 4 patients. sinus Valsalva aneurysm ruptured from the Rt. coronary sinus to the Rt. ventricle, and in one from non-coronary sinus to the Rt. atrium. In 2 cases, resection of the aneurysm and simple stitch closure was made. Resection of the aneurysm k patch closure and AVR in one, closure of the fistula, AVR and patch closure of the associated VSD in one, and closure of the fistula, AVR k TVR in one were made in another 3 cases. There was no postoperative mortality case.

• Journal of Chest Surgery
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• 제20권2호
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• pp.289-299
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• 1987

A total of 1,239 patients had cardiac valve replacement using 1,514 substitute valves at Seoul National University Hospital from 1968 to 1986. Of the total substitute vales, 84.9% were the glutaraldehyde-treated xenograft valves. Six hundred ninety-four patients who had 820 bioprosthetic tissue valves were studied for their clinical characteristics. They were a total and consecutive cases to the end of the study. Four hundred sixty-four patients had the lonescu-Shiley pericardial valves: MVR 291, AVR 66 and MVR+AVR 107; 163 had the Hancock porcine valves; 46 had the Angell-Shiley porcine valves; and 21 had the Carpentier-Edwards porcine valves. Five hundred forty patients underwent single valve replacement: MVR 460, AVR 76 and TVR 4; 154 had multiple valve replacement: MVR+AVR 141, MVR+TVR 12 and one triple valve replacement. Additional surgery was necessary in 22.3% of the cases. Operative mortality rate within 30 days of surgery was 6.77% for the total patients: 5.2% and 4.2% with MVR, 13.6% and 12.5% with AVR, and 7.5% and 7.4% with MVR+AVR using the lonescu and the Hancock valves respectively. A linealized annual late mortality rate was 2.56%/patient-year. Six hundred forty-three operative survivors were followed up for a total of 1482.7 patient-years [a mean 27.7 months], and the follow-up rate was 67.7%. The Idealized complication rates were: 2.02% emboli/patient-year, 0.94% bleeding/patient-year, 1.21% endocarditis/patient-year, and 3.84% overall valve failure/patient-year. A linealized rate of primary tissue failure was 0.87%/patient-year. Actuarial survival rates including the operative mortality were: 87.8*2.6%, 82.3*4.9% and 82.2*4.7% with MVR, AVR and MVR+AVR using the lonescu valves at 4 years after surgery respectively; and they were 88.0*4.1% with MVR at 8 years, 82.3*4.9% with AVR at 4 years and 84.9*7.0% with MVR+AVR at 6 years after surgery using the Hancock valves respectively. Probabilities of freedom from thromboembolism were 89.8*6.3% with MVR using the lonescu valves at postoperative 5 years and 89.2*3.8% with MVR using the Hancock valves at postoperative 7 years, and 93.3*3.9% with AVR using the lonescu valves at postoperative 5 years. None had embolic complication after AVR using the Hancock valves. Probabilities of freedom from valve failure [according to the Stanford criteria] were 81.0*7.1% with MVR using the lonescu valves at postoperative 4 years and 57.4*12.5% with MVR using the Hancock valves at postoperative 9 years. These clinical results prove the excellent antithrombogenicity of the glutaraldehyde-treated xenograft substitute valves and confirm the previously speculated rate of tissue failure. At the present situation, it may be concluded that there is a room for the further development of more durable bioprosthetic valves.

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