• Steel and Composite Structures
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• 제10권3호
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• pp.245-260
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• 2010

In this paper, experimental and theoretical investigations on the response and collapse of 310 stainless steel tubes with different diameter-to-thickness ratios subjected to cyclic bending are discussed. The tube-bending device and curvature-ovalization measurement apparatus were used to conduct the experiment. The endochronic theory combined with the principle of virtual work and finite element software, ANSYS, were used to simulate the moment-curvature and ovalization-curvature relationships. It is shown that although the two methods lead to good simulation of the moment-curvature relationship, the endochronic theory combined with the principle of virtual work has the better simulation of the ovalization-curvature response when compared with experimental data and the simulation by ANSYS. In addition, the theoretical formulations proposed by Kyriakides and Shaw (1987) and Lee et al. (2001) were used to simulate the controlled curvature-number of cycles to produce buckling relationship. It is shown that the theoretical formulations effectively simulate the experimental data.

• Composites Research
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• 제24권1호
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• pp.1-9
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• 2011

본 논문에서는 복합재료 튜브를 이용한 고속 열차의 에너지 흡수장치에 대한 실험 및 수치 해석에 관한 연구를 수행하였다. 논문의 목적은 에너지 흡수장치에 대한 최적의 적층(lay-up) 형태를 알아내는 것으로, quasi static method를 이용한 네 가지 적층 형태에 대한 실험을 수행 하였다: $[0/45/90/-45]_4$, $[0]_{16}$, $[0/90]_8$, $[0/30/-30]_5$, 실험을 위해 초기 파괴 시작점을 생성하고, 일정 방향으로 진행되는 파괴를 만들기 위해 베벨 엣지(bevel edge)와 노치 엣지(notch edge)의 두 가지 트리거링 방법을 이용하였다. 저속 충돌실험 결과 $[0/45/90/-45]_4$의 적층 형태가 다른 방법과 비교해서 가장 좋은 에너지 흡수 결과를 보여주였다. 수치해석을 위해 LS-DYNA 프로그램의 변수 분석(parametric analysis)을 통해 가장 적합한 복합재료의 quasi static 실험 시뮬레이션 방법 연구를 수행하였다. 움직이는 벽이 복합재 튜브에 저속 충돌하는 모델을 가정하여 해석을 수행하였으며, 실험값과 수치해석 결과의 비교를 통해 비슷한 경향을 보임을 확인 하였다. 특히 TFAIL과 mass scaling factor를 조절하며 수행하는 변수 분석은 LS-DYNA에서 복합재 튜브의 quasi static 실험을 시뮬레이션 하는 능력과 한계를 보여준다.

• 대한수의학회지
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• 제45권2호
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• pp.279-285
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• 2005

One-lung ventilation (OLV) is the isolation and selective ventilation of one lung field. OLV allows the collapse of lung lobes on the side of the thoracic surgical approach to facilitate observation of intrathoracic structures and to achieve lung immobility. OLV be achieved by endotracheal intubation with double lumen tubes or bronchial blockers. In this study, cardiopulmonary consequences of two-lung ventilation (TLV), OLV and Re-TLV (TLV after OLV) were evaluated in 5 dogs. The dogs were anesthetized with mask induction and maintained with isoflurane in oxygen. Tidal volume and respiratory rates were set to maintain end-tidal $CO_2$ at $40{\pm}2mmHg$ during instrumentation. Following instrumentation, the dogs were placed in right lateral recumbency and induced spontaneously respiration state. Effect of TLV on hemodynamic and pulmonary variables were recorded. Then, the left bronchus was obstructed by endotracheal intubation with double lumen endotracheal tube to achieve OLV state and recording was continued. After OLV, double lumen endotracheal tube was extubated, and standard endotracheal tubes was intubated again. In this study, spontaneous OLV caused significant decrease in $PaO_2$, arterial oxygen saturation, mixed-venous oxygen saturation, and increase in $PaCO_2$. Especially, a significant elevation in $PaCO_2$ and respiratory acidosis were remarkable findings. So spontaneous ventilation in OLV affected gas exchange and hemodynamic function.

• Tuberculosis and Respiratory Diseases
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• 제43권3호
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• pp.410-419
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• 1996

연구배경 : 자연기흉은 장측 늑막이 파열되어 늑막강내에 공기가 누출되면서 폐의 일부 또는 전부가 허탈된 상태로, 치료 방법은 환자의 증상, 기흉의 크기, 원인, 과거 발생 여부 등에 따라 달라서, 산소흡입을 하면서 관찰하거나, 흉강천자, 흉관삽입술, 화학적 흉막유착술과 수술을 시행한다. 하지만, 크기가 20%~25% 이상인 자연 기흉의 치료에 있어서 가장 흔히 사용하는 방법은 흉관삽입술로, 이는 시술 중 통증이나, 감염, 출혈, 피하기종 등의 합병증을 동반할 수 있고, 일반적으로 외과의에 의해 시행되는 특별한 기술이 요구되는 방법이다. 그러나, 근래 경피적 주사 흡인 폐조직 검사와 같은 침습적인 진단방법에 의한 의인성 기흉이 늘면서 작은 직경의 도관 삽입이 시도되어 특별한 합병증 없이 좋은 결과를 나타냈으나 자연기흉의 치료에 있어서 작은 직경 도관의 유용성은 아직 확실하지 않다. 이에 본 연구에서는 자연기흉 환자들을 대상으로, 8 French 도관의 유용성을 보기 위하여, 8 French 도관 삽입 군과 흉관삽입군의 임상양상을 비교 연구하였다. 방법 : 1990년 1월부터 1994년 4월까지 중앙대학교 부속병원 내과와 흉부외과에서 치료받은 자연기흉 환자 44명을 대상으로 하여, 8 French 도관을 삽입한 군(21명)과 흉관을 삽입한 군(23명)사이에서, 자연 기흉의 발생 원인, 기흉의 크기, 도관 유치 기간과 합병증 등을 비교 분석하였다. 결과 : 1) 도관 유치 기간은 8 French 도관 삽입군과 흉관 삽입군에서 유의한 차이가 없었으나, 삽입 후 합병증은 8 French 도관 삽입군에서는 1예도 없었고 흉관 삽입군에서는 피하기종의 발생이 유의하게 높게 발생하였다. 2) 원발성 자연기흉에서 기흉의 크기가 50%이하인 경우엔 양 군에서 100%의 성공율을 보였고, 50% 이상이라도 나이가 적은 경우엔 8 French도관 삽입의 성공율이 높은 경향을 보였다. 3) 속발성 자연기흉에서 8 French도관을 삽입하였을 경우, 기저 질환으로서 만성 폐쇄성 페질환이 없고 나이가 적을수록 성공률이 높은 경향이 있었다. 결론 : 자연기흉의 치료에 있어서 기흉의 크기가 50% 이하이거나 원발성 자연기흉의 경우, 나이가 젊고 만성 폐쇄성 폐질환이 없는 속발성 자연기흉 환자의 경우는 8 French 도관 삽입을 고려해 볼만 하다고 생각된다.

• 대한치과교정학회지
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• 제40권2호
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• pp.66-76
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• 2010

폐쇄성 수면무호흡(obstructive sleep apnea, OSA)은 수면 중에 반복적으로 상기도의 완전폐쇄나 부분폐쇄가 일어나는 질환으로서 흡기된 공기는 반드시 상기도라는 연조직 관(tube) 구조를 통과해야 하므로 상기도의 폐쇄경향은 관의 형태 및 관을 통과하는 공기의 유체역학적 특성에 따라서도 큰 영향을 받을 수 있다. 본 연구에서는 OSA 환자 3인의 치료 전 상기도 CT 이미지를 이용하여 개별화된 3차원 유한요소모델 A, B, C를 제작하고, 비공 당 170, 200, 230 ml/s의 흡기유량에 대하여 3차원 전산유체역학 해석을 시행하였다. 상기도의 유속, 음압 그리고 압력강하를 측정한 결과 관찰된 3개의 모델에서 모두 단면적이 가장 작은 부위에서 유속이 증가하였고, 음압이 크게 나타났다. 기도의 형태는 구개인두와 구인두 부위에서 좁아지는 형태를 가지며, 최소 단면적 영역과 하인두 단면적의 차이가 클수록 유속과 음압의 변화가 크게 나타났다. 비강 부위의 최고 압력과 최소 단면적 영역의 최저 압력의 차이를 의미하는 압력강하는 상기도 저항을 종합적으로 판단할 수 있는 유용한 지표이며, 유량에 따라 증가하였다.

• International Journal of Aeronautical and Space Sciences
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• 제13권3호
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• pp.386-397
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• 2012

The stability and structure of bluff-body stabilized hydrogen flames were investigated numerically and experimentally. The velocity of coflowing air was varied from subsonic velocity to a supersonic velocity of Mach 1.8. OH PLIF images and Schlieren images were used for analysis. Flame regimes were used to classify the characteristic flame modes according to the variation of the fuel-air velocity ratio, into jet-like flame, central-jet-dominated flame, and recirculation zone flame. Stability curves were drawn to find the blowout regimes and to show the improvement in flame stability with increasing lip thickness of the fuel tube, which acts as a bluff-body. These curves collapse to a single line when the blowout curves are normalized by the size of the bluff-body. The variation of flame length with the increase in air flow rate was also investigated. In the subsonic coflow condition, the flame length decreased significantly, but in the supersonic coflow condition, the flame length increased slowly and finally reached a near-constant value. This phenomenon is attributed to the air-entrainment of subsonic flow and the compressibility effect of supersonic flow. The closed-tip recirculation zone flames in supersonic coflow had a reacting core in the partially premixed zone, where the fuel jet lost its momentum due to the high-pressure zone and followed the recirculation zone; this behavior resulted in the long characteristic time for the fuel-air mixing.

• Journal of Chest Surgery
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• 제24권5호
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• pp.451-458
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• 1991

We have observed 101 cases of recurrent spontaneous pneumothorax from Sep. 1979 to Dec. 1989 at the Department of Thoracic & Cardiovascular Surgery, College of Medicine, Inje University, Pusan Paik Hospital and the result obtained as follows. 1] Age range of patients was the first decade to seventh decade. Males outnumbered females by 6.7: l. One or two episodes of recurrent attack were noted in majority cases. 2] In distribution of the lesion sites, right side was 55 cases[55.4%], left 42 cases[41.9%], and bilateral 4 cases[3.0%]. 3] In clinical manifestations, abrupt onset of dyspnea was 78 cases[77.2%], chest pain 48 cases[47.5%], cough 9 cases[8.9%] and chest discomfort 8 cases[7.9%]. 4] Of 101 cases, 48 cases were associated with pulmonary tuberculosis and other cases were associated with subpleural bullae and blebs[26 cases], emphysema[7 cases], bronchiectasis[2 cases], lung cancer[1 case], and silicosis[1 case], 5] In 88 cases[87.2%] of patients, the magnitude of collapse was above 50% in plain chest film. 6] The interval of recurrence after last attack was frequently within 1 year. 7] In the management, closed thoracostomy with underwater-sealed drainage was applied in first recurrent 53 cases but 2nd recurrence was developed in 16 cases. In 52 cases, surgical management was applied. The pleurodesis with chemical agent[tetracycline] via chest tube was applied in 2 cases. Among 51 cases subjected to the open thoracotomy, pleural abrasion was performed in 3 cases, excision of bullae & blebs in 12 cases, wedge resection in 28 cases, lobectomy in 6 cases and wedge resection combined with lobectomy in 2 cases. In one case subjected to the median sternotomy, wedge resection on both lung apex was performed. 8] Postoperative complications were developed in 8 cases but not serious.

• Computers and Concrete
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• 제12권2호
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• pp.211-228
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• 2013

The structure analyzed in this paper has particular building style and special structural system. It is a rigid-connected twin-tower skyscraper with asymmetrical distribution of stiffness and masses in two towers. Because of the different stiffness between the north and the south towers, the torsion seismic vibration is significant. In this paper, in order to study the seismic response of the structure under both frequent low-intensity earthquakes as well as rare earthquakes at the levels of intensity 7, the analysis model is built and analyzed with NosaCAD. NosaCAD is an nonlinear structure analysis software based on second-development of AutoCAD with ObjectARX. It has convenient modeling function, high computational efficiency and diversity post-processing functions. The deformations, forces and damages of the structure are investigated based on the analysis. According to the analysis, there is no damage on the structure under frequent earthquakes, and the structure has sufficient capacity and ductility to resist rare earthquakes. Therefore the structure can reach the goal of no damage under frequent earthquakes and no collapse under rare earthquakes. The deformation of the structure is below the limit in Chinese code. The time sequence and distribution of damages on tubes are reasonable, which can dissipate some dynamic energy. At last, according to forces, load-carrying capacity and damage of elements, there are some suggestions on increasing the reinforcement in the core tube at base and in stiffened stories.

• 대한한의학회지
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• 제18권2호
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• pp.148-154
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• 1997

In the pharmacology of traditional Korean medicine, each drug has its own specific characters. The different characters of drugs are employed to treat diseases, rectify the hyperactivity or hypoactivity of yin or yang, and help the body restore its normal physiological functions, consequently curing the diseases and restoring health. The various characters and functions of these drugs concerning medical treatment include drugs' properties, flavours, actions of lifting, lowering, floating and sinking, channel tropism, toxicity, etc. Among these theories, theory of properties and flavours of drugs provides the basis for drug analysis and application. 'Property' refers to the cold, hot, warm or cool nature of a drug. These properties of drugs are so sorted out according to the different actions of the drugs on the human body and thier therapeutic effects. Drugs which cure heat syndrome(yang syndrome) have a cold or cool property, whereas drugs which cure cold syndrome (yin syndrome) have hot or warm property Drugs of cold and cool-natured and drugs of warm and hot natures are of opposite properties. A cold-natured drug is different from a cool-natured on only in degree, and so is a warm-natured drug from a hot-natured drug. Most of the cool- or cold- natured drugs have the effects of clearing heat, purging fire, removing toxic substances, and nourishing yin, and are uese to cure heat syndromes. On the contrary, drugs of warm or hot nature usually have the effects of dispersing cold, warming up the interior, supporting yang, and treating collapse, and are therefore used to treat cold syndromes. We thought that the property of drug may be related to the autonomic nervous system in western medicine. In other words, drugs of warm or hot nature increase heart rate or acts like sympathomimetics, and drugs of cool or cold nature decrease heart rate or acts like para sympathomimetics . According to this hypothesis, we administrated some drugs to isolated rat right atrium in magnus tube. But there is no correlation between 'property' in traditional Korean medicine and autonomic nervous system in western medicine.

• Journal of Chest Surgery
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• 제27권3호
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• pp.226-229
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• 1994

VATS is now used by many thoracic surgeons and in various anatomic locations such as lung parenchyme, pleura and mediastinum, etc. VATS of mediastinal masses has special characteristics compared to that of other diseases. Those are no positional changes of the mass during collapse of the lung and close proximity of the mass to major vascular structures, nerves and other vital organs. From 1992. July to 1993. August, 10 mediastinal masses were treated with video assisted thoracoscopy. There were five males and five females, ages ranged from 11 years to 65 years with average 37.7 17.7 years old. Of the 10 patients, 4 were bronchogenic cysts, 2 were teratoma, and the others were thymoma, neurilemmoma, pericardial cyst, and thymic cyst. Needle aspiration was done in large cysts and the working thoracotomy[or utility thoracotomy] was done in large solid masses for the purpose of easy dissection, easy handling and easy delivery of the mass. The average operation time were 155.6 6.8 minutes and the duration of air leakage were 1 2.2 days. The duration of the chest tube drainage were 3.3 2.6 days. The lengths of the postoperative hospitalization were 5.1 2.7 days which were shorter than those of 12 mediastinal masses treated with conventional thoracotomy during the same periods [p<0.05]. There was 1 patient converted to thoracotomy because of a bleeding at innominate vein. 3 postoperative complications were occured. Those were persistent air leakage for 7 days, diaphragmatic palsy and hoarseness which were recovered within 1 month. We conclude that mediastinal mass can be excised with video assisted thoracoscopy and the posthospitalization is reduced. But careful attention is required for avoiding injury to major vascular structures, nerves, and other vital organs.