• Journal of Chest Surgery
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• 제23권4호
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• pp.617-621
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• 1990

A heart supplies blood of about 15, 000 liters to each human organ in a day. A normal function of heart valves is necessary to accomplish these enormous work of heart. The disease of heart valve develops to a narrowness of a closure, resulting in an abnormal circulation of blood. In an attempt to eliminate the affliction of heart valves, the operative method to replace with artificial heart valves has developed and saved numerous patients over past 30 years. This replacement operation has been performed since early 1960`s in Korea, but all the artificial heart valves used are imported from abroad with very high costs until recent years. New artificial heart valves have been developed in Korea Advanced Institute of Science and Technology since early 1980`s. The first developed valve was designed with a free-floating pyrolytic carbon disk that is suspended in a titanium cage. The design of the valve was tested in vitro, and in animals in 1987. The results from this study was that the eccentrically placed struts creates a major and minor orifice when the disc opens and stagnation of flow in the area of the minor orifice has led to valve thrombosis. In this work, the design of the valve was changed from a single - leaflet valve to double - leaflet one in order to resolve the problems observed in the first - year tests. Morphological and hemodynamic studies were made for the newly designed valves through the in vitro and in vivo tests. The design and partial materials of the artificial heart valve was improved comparing with first - year`s model. The disc in the valve was modified from single - leaflet to bi - leaflet, and the material of the cage was changed from titanium metal to silicon - alloyed pyrolytic carbon. A test was made for the valve in order to examine its mechanical performance and stability. Morphological and hemodynamic studies were made for the valve that had been implanted in tricuspid position of mongrel dogs. All the test animals were observed just before the deaths. A new artificial heart valve was designed and fabricated in order to resolve the problems observed in the old model. The new valve was verified to have good stability and high resistance to wear through the performance tests. The hemodynamic properties of the valve after implantation were also estimated to be good in animal tests. Therefore, the results suggest that the newly designed valve in this work has a good quality in view of the biocompatibility. However, valve thrombosis on valve leaflets and annulus were found. This morphological findings were in accordance with results of surface polishing status studies, indicating that a technique of fine polishing of the surface is necessary to develop a valve with higher quality and performance.

• Journal of Chest Surgery
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• 제30권4호
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• pp.373-377
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• 1997

소아에서의 선천성 승모판 폐쇄부전은 다른 기형의 동반과 함께 일찍 심부전을 일으키게 되나 기계 판막과 조직 판막 모두 소아에서는 한병증과 재수술을 요하는 바 자신의 조직을 최대한 이용하여 교정하는 것이 바람직하다. 1991년 1월부터 1995년 5월까지 15세이하의 소아에서 선천성승모판폐쇄부전증으로 32예에서 교정수술을 시행하였다. 나이는 3개월에서 9년 7개월(평균 24.0 $\pm$26.1) 이었으며 남아가 16예, 여아가 16예 였다. 26예(81 %)에서 심장기형을 동반하였으며 이중 심실중격결손증이 18예를 차지하고 있었다. 수술시 승모판막의 병리적 소견을 보면 판막윤의 확장만을 보인 경우가 7예, 판막침의 탈출증이 18예, 판막에 열이 있는 경우가 5예 그리고 판막침의 운동장애를 보인 경우가 2예 있었다. 판막의 교정은 판막윤 성형술만을 시행한 경우가 14예, redundant leaflet을 교정한 경우가 6예, 판막열을 폐쇄한 경우가 5예, 판막삭의 축소를 시행한 경우가 4예, 판막의 부분절제가 2예, 유두상근의 분리를 1예에서 시행하였다. 수술사망은 없었으며 만기사망은 심부전과 패혈증으로 2예에서 발생되었다. 추적관찰시 8예 에서 교정된 판막의 부전이 濚森퓸\ulcorner이중 2예에서 재수술을 시행하여 판막을 인공판막으로 치환하였다. 모든 환아의 46개월의 생존율은 92.5%를 보였으며 재수술회피율은 12개월, 46개월시 95%와 92.5% 를 보였고 판막교정의 실패율은 12개월,46개월시 68.7%와 61 8%를 보였다. 그러므로 소아에서 승모판의 교정수술은 비록 판막교정의 실패율은 높지만 낮은 사망과 낮은 재의 위험성을 보이기 때문에 소아에서 승모판폐쇄부전증은 가능곤판막의 재건으로 치료해야 할것으로 생각된다.

• 한국응용곤충학회지
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• 제37권2호
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• pp.151-157
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• 1998

충남부여에 위치한 임업화훼단지내의 유리온실에서 아치형재배(Arching method)장미에 피해를 주는 점박이응애(Tetranychus urticae Koch)의밀도를 엽당 응애수로 조사하였다. 이항표본 조사법은 엽당 점박이응애의 평균밀도(m)와 점박이응애가 T 개체보다 많이 존재하는 엽의 비율(${P}_{T}$)과의 관계를 기본으로 하며, T는 경험적 이항분포모형(ln(m)=$\alpha$+$\beta$1n(-1n(1-${P}_{T}$)))에서의 tally threshold 로서, 본 실험에서는 1, 3, 5, 7, 9를 사용하였다. 일반적으로 표본단위 수의증가는 T와 상관없이 이항분포 모형의 정확도에 영향을 거의 주지 않게 된다. 본 실험에서는 상이한 T에 따라 이항분포모형의 정확도가 차이가 났으며 T가 증가할수록 정확도가 높아졌다. 본 실험결과 점박이응애의 밀도추정을 위한 이항분포모형의 정확도를 비교한 결과, T=7인 경우가 최적의 tally threshold인 것으로 나타났다. 또한 이항분포조사법의 검정을 위하여, 동일한 포장의 독립적인 표본을 추출, 조사하였다. 본 실험결과 이항표본조사법을 이용한 상업적 유리온실의 아치형재배 장미해충인 점박이응애 평균밀도 추정에는 T=7인 경우가 가장 적절한 것으로 사료된다.

• Journal of Chest Surgery
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• 제47권4호
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• pp.398-401
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• 2014

Severe tricuspid regurgitation resulting from a flail leaflet is a rare cause of neonatal cyanosis. We report a neonate with profound cyanosis and severe tricuspid regurgitation caused by a rupture of the papillary muscle supporting the anterior leaflet, without other structural heart defects. Ductal patency could not be established. The repair of the tricuspid valve was performed after initial stabilization by using extracorporeal membrane oxygenation.

• 식물분류학회지
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• 제44권3호
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• pp.175-177
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• 2014

전남 가거도에서 양지꽃속의 신종인 가거양지꽃(Potentilla gageodoensis M. Kim)을 새로이 발견하여 기재하였다. 가거양지꽃은 잎은 우상복엽이며 엽신과 엽병에 털이 있고 3개의 정소엽이 측소엽보다 크며 포복경이 없어 양지꽃과 유사하다. 그러나 가거양지꽃은 잎은 두껍고 근생엽은 흔히 5장의 소엽으로 이루어졌으며 정소엽은 광난형이고 꽃잎이 크며 소엽 가장자리에 흰털이 밀생해서 흰색 테두리가 있는 것처럼 보인다. 반면에, 양지꽃은 잎은 얇고 근생엽은 흔히 7-13장의 소엽으로 이루어졌으며 정소엽은 타원형이고 꽃잎이 작으며 소엽 가장자리에 흰털이 적은 점에서 두 종이 뚜렷하게 차이가 난다.

• 한국응용곤충학회지
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• 제36권1호
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• pp.83-87
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• 1997

붉나무에서 오배자면충의 오배자 형성 기작과 오배자면충의 발육 및 붉나무 잎 부위별 오배자 형성수를 조사한 결과, 오배자면충의 간모 출현에 의한 충영(오배자)형성 시기는 6월 중순이었으며 간모는 미성숙된 입엽의 뒷면에 정착기생한 뒤 반대방향으로 융기하여 충영을 형성하였다. 오배자는 9월 중순부터 급격히 발육하였으며 면충의 밀도가 많음에 따라 오배자의 무게도 무거웠다. 붉나무에서 오배자면충의 충영 형성 부위는 정엽에서 가까울수록 많았으며 복엽상에서는 익엽이 95.8%를 차지하였다.

• Journal of Plant Biotechnology
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• 제35권3호
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• pp.223-228
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• 2008

This study was conducted to investigate an optimal condition for shoot proliferation and regenerate shoots from in vitro leaflet and embryogenic calli from in vitro roots in rose. The effect of BAP on shoot proliferation was somewhat different depending upon genotypes or gelling agents. Leaflets with petiole cut from donor shoots which had been cultured in MS medium supplemented with 0.1 $mg{\cdot}L^{-1}$ NAA for six weeks was effective for regeneration of adventitious buds(ABs) as well as shoot elongation of Rosa hybrida cv. Sweet Pink. Culturing seven leaflet explants per petri plate($100mm{\times}15mm$) was effective for regeneration of ABs. Embryogenesis was shown in the calli induced from roots of Rosa hybrida cv. Sweet Pink cultured in the SH medium supplemented with 11 $mg{\cdot}L^{-1}$ 2, 4-D for four weeks. Color of calli induced from roots was yellow although their color was a little different as type of basal medium.

• Journal of Chest Surgery
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• 제18권2호
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• pp.299-304
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• 1985

The partial A-V canal defect consist of ostium primum type atrial septal defect with a cleft mitral anterior leaflet. The clinical findings depend upon the site and size of the left-to-right shunt, the degree of A-V valvular regurgitation, and the degree of resultant pulmonary artery hypertension. We experienced 3 cases of similar condition. The data were as follow: 1. Chest P-A showed increased pulmonary vascularity and moderate cardiomegaly with left atrial enlargement. 2. E.K.G. showed left axis deviation, left atrial enlargement, and left ventricular hypertrophy. 3. Right heart catheterization showed significant 02 step up of SVC-RA and left-to-right shunt. 4. Left ventriculogram showed mitral regurgitation and filling of both atrium. Operative findings were as follow: 1. Primum type atrial septal defect [2x2 cm]. 2. Cleft in the anterior leaflet of the mitral vave. 3. No evidence of ventricular septal defect and tricuspid anomaly. Through a right atriotomy with moderate hypothermia, the mitral cleft was approximated with interrupted sutures. The interatrial communication was closed by a patch of Dacron/pericardium. The patch was attached to junction of the mitral and tricuspid valves along the crest of the ventricular septum using interrupted sutures and the other site using continuous sutures. Postoperative course was uneventful and discharged in good general condition except postoperative bleeding in case 3.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1339-1348
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• 2003

Several factors, including peak dp/dt of the ventricular pressure and maximum closing velocity of leaflet have been studied as indices of the cavitation threshold. In the present study, just before closing velocity of the leaflet has been studied as indices of the cavitation threshold, and cavitation erosion on the surface of a mechanical valve was examined by focusing on squeeze flow and the water hammer phenomenon during the closing period of the valve. A simple solenoid-actuated test device that can directly control the valve closing velocity was developed, and opening-closing tests of 3,000 and 40,000 cycles were performed at various closing velocities. There was a closing velocity threshold to occur erosion pitting of valve surface, and its value was about 0.4 m/s in this study. Cavitation-induced erosion pits were observed only in regions where squeeze flow occurred immediately before valve closure On the other hand, the number of the pits was found to be closely related to an area of water hammer-induced pressure wave below the critical pressure defined by water vapor pressure. Therefore, it was concluded that cavitation is initiated and augmented by the two pressure drops due to squeeze flow and water hammer phenomenon, respectively.

• 펄프종이기술
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• 제47권5호
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• pp.43-51
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• 2015

This research was performed to investigate the quality of leaflets provided with newspapers. The leaflets were classified according to business types and regions. The physical and strength properties were analyzed. The sizes of leaflets were 2, 4, 8 jeoljis of crown octavo, A3, A4, A5, and B3, B4, B5. Most of them were color printed and both-sides printing was much more popular than one-side printing. The leaflets about electronics, educations, and clothing showed lower density than restaurant business and other areas. The leaflets of electronics, educations, and clothing, and large stores showed lower tensile strength, and those of restaurant businesses and building trades showed relatively high tensile strengths. No differences on the quality of leaflets except for large stores were found according to business areas. Large markets made the leaflets with various types of papers, and low quality papers were also included.