• Journal of Chest Surgery
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• 제22권4호
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• pp.594-600
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• 1989

Primary intracardiac repair of tetralogy of Fallot with low mortality and early good results, has been accomplished in recent years. But palliative procedures have been reserved for those hypoplastic pulmonary arteries, a hypoplastic left ventricle or anomalies of the coronary artery would make total correction difficult. And the Blalock-Taussig shunt operation is recognized as a standard and popular palliative procedure. I undertook a retrospective determination of the effect of the Blalock-Taussig shunt operation on the development of the main pulmonary artery and the right and left pulmonary arteries. Between January, 1980, and April, 1987, at the Severance Hospital, 16 patients were studied by cardiac catheterization and angiocardiography, before undergoing Blalock-Taussig shunting procedures for the palliation of severe symptoms of tetralogy of Fallot, and some time later, usually prior to a second procedure. The mean interval between catheterizations was 22.25 months. Patients with tetralogy of Fallot and pulmonary atresia or with an occluded shunt were not included. The primary and secondary angiograms of each patient were reviewed, and measurements of the diameter of the main pulmonary artery, the right and left pulmonary arteries, and the descending thoracic aorta were taken. The results are as follows; 1. The hematocrit decreased from 56.39% to 50.34%[p< 0.05], and the arterial oxygen saturation increased from 62.00 % to 81.31 %[p< 0.001] following shunt procedures 2. The ratio of the diameter of the right pulmonary artery plus the left pulmonary artery to the diameter of the descending thoracic aorta increased 1.30 k 0.28 times [p< 0.01]; but the ratio of the diameter of the main pulmonary artery to the diameter of the descending thoracic aorta increased 1.10 * 0.33 times, which was not. significant[p< 0.05]. 3. The interval between shunting and second catheterization was not related to the magnitude of change in the pulmonary arteries[r=0.141, p >0.05]. 4. The changes in the ratio of the diameter of the right pulmonary artery plus the diameter of the left pulmonary artery to the diameter of the descending thoracic aorta was inversely related to the initial ratio[r=0.757, p >0.001], but the change in the ratio of the diameter of the main pulmonary artery to the descending thoracic aorta was not related[r=0.059, p >0.05]. 5. There were no differences in enlargement of the pulmonary artery on the side of the shunt [ipsilateral] versus enlargement on the opposite side [p >0.05], nor according to the size of the shunt[p >0.05]. In conclusion, this study suggests that the Blalock-Taussig shunt is effective for the development of the right and left pulmonary arteries but not effective for the main pulmonary artery.

• 산업기술연구
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• 제27권B호
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• pp.71-75
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• 2007

A cylindrical pin fin with variable diameter is analyzed by using the one dimensional analytical method. Heat loss and fin efficiency are presented as a function of the fin diameter, length and convection characteristic numbers ratio. The relationship between the fin diameter and convection characteristic number over the fin for the same amount of heat loss is shown. One of the results indicates the fin efficiency increases as the fin diameter increases while that decreases as the fin length increases.

• Journal of Forest and Environmental Science
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• 제33권2호
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• pp.97-104
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• 2017

Investigation was carried out on response of Tetrapleura tetraptera (Schum. and Thonn.) to soil, water and light with the view of its domestication and introduction to different ecological regions. The experiment was arranged in a factorial experiment of $3{\times}3{\times}3$ in a completely randomized design (CRD) with three replicates. The factors were: soil textural class (Loamy sand, Sand and Sandy clay loam), watering regime (daily, twice a week and once a week) and light intensity (100%, 75% and 50%). Soil textural classes had significant influence on collar diameter, stem height, number of leaflets, root/shoot ratio and relative growth rate of Tetrapleura seedlings. Seedlings grown on loamy sand recorded the highest mean value- 2.28 mm for collar diameter, stem height- 12.9 cm, number of leaflets- 19.9, chlorophyll b- $0.34mg\;mL^{-1}$, leaf relative water content- 27.4% and relative growth rate- $0.037mg\;g^{-1}\;day^{-1}$. Watering regime had significant influence on the collar diameter of Tetrapleura. Seedlings watered daily recorded the highest mean value- 2.25 mm for collar diameter. Light intensity significantly influenced collar diameter and root/shoot ratio. Seedlings exposed to 100% light intensity recorded higher mean value for collar diameter- 2.28 mm and root/shoot ratio- 1.481 cm. The interaction between soil textural class and light intensity significantly affected collar diameter, stem height and number of leaflets. Higher mean value for collar diameter (2.47 mm) stem height (13.25 cm) and number of leaflets (21.16) were recorded while the interaction between soil textural class, light intensity and watering regime was significant for only number of leaflets. Tetrapleura exhibited some level of tolerance to different soil texture, drought and light intensity. Therefore, Tetrapleura has the potentials to be raised in different ecological zones characterized by difference in soil, rainfall and amount of sunshine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.694-697
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• 2003

Materials with specific micro-structural shape can exhibit negative Poisson's ratio. These materials can be widely used in structural applications because of their high resilience and resistance to impact. Specially, in the field of artificial implant's material, they have many potential applications. In this study, we investigated the Poisson's ratio and the ratio(E$_{e}$/E) of the elastic modulus of rotational particle structures based on structural design variables using finite element method. As the ratio of fibril's length to particle's diameter increased and the ratio of fibril's diameter to fibril's length decreased fixing the fibril's angle with 45 degree. the negative Poisson effect of rotational particle structures increased. The ratio of elastic modulus of these structures decreased with Poisson's ratio. The results show the reasonable values as compared with the previous analytical results.s.

• 대한의용생체공학회:의공학회지
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• 제24권2호
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• pp.113-119
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• 2003

본 연구에서는 end-to-end 문합시 변형된 직경의 불일치로 인하여 발생하게 되는 혈관질환을 방지하기 위하여 기계역학적 거동을 유한요소 법을 이용하여 해석한 결과를 나타내었다. 이 연구에서는 서로 다른 직경을 가지는 동맥과 인공혈관인 PTFE의 문합시 봉합으로 인한 예변형을 고려하였으며, 봉합된 문합부에 수축기혈압인 120mmHg(16.0KPa)을 작용시켜 혈관의 변형을 분석하였다. 변형 후 최종 문합부의 형상은 동맥과 PTFE의 초기 직경비(R$_{I}$)와 PTFE의 두께에 대하여 분석하였다. 그리고 동맥과 PTFE의 초기 직경비가 문합부에서 발생되는 응력에 어떠한 영향을 미치는지에 대하여 해석하여 다음과 같은 결과를 얻었다. 1. 혈관내막의 증식등을 고려하지 않고 봉합으로 인한 예변형과 수축기 혈압만을 고려할 경우 가장 이상적인 초기 직경비(R$_{I}$)는 1.073이다. 2. 상당응력과 원주방향응력은 초기 직경비(R$_{I}$) 증가에 따라 증가하며 모두 접합부에서 PTFE측으로 0.4mm 떨어진 지점에서 최대값이 발생하였다.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.94-100
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• 2007

The purpose of this work is to investigate the effect of properties of diesel and biodiesel fuels on the nozzle cavitation and the effect of the length/diameter(L/D) ratio on internal and external flow pattern of nozzle at the various injection conditions. In order to study the effect of the L/D ratio on the nozzle cavitation characteristics of diesel and biodiesel, the characteristics of cavitation flow in the nozzle are visualized and analyzed at the injection pressure of 0.1 MPa to 0.7 MPa by using the visualized images. It was founded that the cavitation was formed in the nozzle orifice at the low injection pressure and the breakup of the issuing liquid jet was promoted at the low L/D ratio. When the L/D ratio decrease, cavitation beginning and growth were affect by cavitation number and Reynolds number.

• 한국임상수의학회지
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• 제29권4호
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• pp.301-305
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• 2012

기초 검사를 통해 위장관계와 위장관 운동에 영향을 줄 수 있는 전신 질환이 없는 12 두의 5 kg 이하의 소형견들을 선별하여 사용하였다. 조영 전 단순 방사선 검사를 실시한 후, 30% 바륨을 체중 kg 당 12cc 를 위관 튜브를 통해 주입하였다. 그 후 일련의 방사선 사진을 촬영한 후, 우측횡와상과 복배상을 촬영하여 소장에 조영제가 골고루 분포된 사진을 선별하여 분석하였다. PACS viewer에서 우측횡와상 방사선 사진을 확대하고 대비도를 조정하여 조영된 장과 비교하고자 하는 해부학적 구조인 5번째 요추의 윤곽선이 뚜렷이 영상화되도록 한 후, 내장된 전자 caliper를 이용하여 최대 장직경과 5번째 요추의 가장 좁은 부분의 높이를 측정하였다. 복배상에서 역시 장직경과 12번째 늑골의 가장 넓은 부위의 경을 측정하였다. 위의 측정치를 소장과 요추 비율 (SI/L5 ratio) 그리고 소장과 늑골 비율 (SI/Rib ratio)로 명명하여 주로 대형견의 자료인 이전 연구와 비교평가하였다. 소형견에서의 SI/L5 ratio의 범위는 조영전 1.03-2.26 그리고 조영후 1.55-2.5 였으며, SI/Rib ratio는 조영전 2.16-4.52, 그리고 3.67-6.04 였다. 이는 이전부터 사용되어 오던 상위 한계인 SI/L5 ratio 1.6과 SI/Rib ratio 2 보다 높은 수치이며, 이러한 차이는 대형견에 비해 상대적으로 작은 골격구조 때문인 것으로 생각된다. 따라서 소형견에서는 정상 소장과 요추 비율의 상위 한계가 1.8배이며, 2.1배 이상일 경우 기계적 폐색을 의심할 수 있을 것으로 생각된다.

• 한국임상수의학회지
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• 제29권5호
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• pp.391-394
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• 2012

기초 검사를 통해 위장관계와 위장관 운동에 영향을 줄 수 있는 전신 질환이 없는 12 두의 5 kg 이하의 소형견들을 선별하여 사용하였다. 조영 전 단순 방사선 검사를 실시한 후, 30% 바륨을 체중 kg 당 12cc 를 위관 튜브를 통해 주입하였다. 그 후 일련의 방사선 사진을 촬영한 후, 우측횡와상과 복배상을 촬영하여 소장에 조영제가 골고루 분포된 사진을 선별하여 분석하였다. PACS viewer에서 우측횡와상 방사선 사진을 확대하고 대비도를 조정하여 조영된 장과 비교하고자 하는 해부학적 구조인 5번째 요추의 윤곽선이 뚜렷이 영상화되도록 한 후, 내장된 전자 caliper를 이용하여 최대 장직경과 5번째 요추의 가장 좁은 부분의 높이를 측정하였다. 복배상에서 역시 장직경과 12번째 늑골의 가장 넓은 부위의 경을 측정하였다. 위의 측정치를 소장과 요추 비율 (SI/L5 ratio) 그리고 소장과 늑골 비율 (SI/Rib ratio)로 명명하여 주로 대형견의 자료인 이전 연구와 비교평가하였다. 소형견에서의 SI/L5 ratio의 범위는 조영전 1.03-2.26 그리고 조영후 1.55-2.5 였으며, SI/Rib ratio는 조영전 2.16-4.52, 그리고 3.67-6.04 였다. 이는 이전부터 사용되어 오던 상위 한계인 SI/L5 ratio 1.6과 SI/Rib ratio 2 보다 높은 수치이며, 이러한 차이는 대형견에 비해 상대적으로 작은 골격구조 때문인 것으로 생각된다. 따라서 소형견에서는 정상 소장과 요추 비율의 상위 한계가 1.8배이며, 2.1배 이상일 경우 기계적 폐색을 의심할 수 있을 것으로 생각된다.

• 대한기계학회논문집
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• 제19권2호
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• pp.509-518
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• 1995

A study for the flame stability and the combustion characteristics of coaxial diffusion flame was conducted. The fuel employed was natural gas. The experimental variables were rim thickness of fuel tube, blockage ratio of the outer diameter of fuel tube to the inner diameter of air tube, and momentum ratio of fuel to air. It was consequently found that the stability in the neighborhood of the fuel rim depended on the rim thickness, especially in the case of above 3 mm, and that the stable region of the flame extended remarkably due to the formation of recirculation zone above rim. The effect of the blockage ratio on the flame stability was found to be minor in the case of above 3 mm of rim thickness. Between the momentum ratio 2 and 3, the stable flame zone was widely established as well good combustion. With increasing the fuel-air momentum ratio, axial velocity, turbulence intensity, and Reynolds stress increased.

• 한국유체기계학회 논문집
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• 제15권4호
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• pp.19-26
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• 2012

In this paper, a parametric study on ribs which are installed in an equilateral triangular internal cooling channel is presented. The numerical analysis of the flow structure and heat transfer characteristics is performed using three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. The numerical results are obtained at Reynolds number, 20,000. The parametric study is performed for the parameters, the angle of a rib, rib pitch-to-hydraulic diameter ratio, rib width-to-hydraulic diameter ratio, and rib height-to-hydraulic diameter ratio. The computational results are validated with the experimental data for area-averaged Nusselt number.