• 대한조선학회지
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• 제13권3호
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• pp.1-9
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• 1976

A numerical method for solving the boundary-value problem related to potential flows with a free surface and an experimental work are introduced in this paper. The forced heaving motion of cylinders with arbitrary shapes in water of finite depth are Considered here. The Fredholm integral equation of the first kind is employed in determining strengths of singularities distributed on the body surface. And the results obtained by the present method for the case of a heaving circular cylinder on water of finite depth agree well with existing results of earlier investigators.

• 한국정밀공학회지
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• 제13권8호
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• pp.155-163
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• 1996

This paper presents vibration and position tracking control of a smart structure using shape memory alloy(SMA) actuators. A governing equation of motion of the proposed structure is obtained via Hamilton's princeple. The dynamic characteristics of the SMA actuator are experimentally identified and incorporated with the governing equation to furnish a control system model. Subsequently, a sliding mode controller which has inherent robustness to external disturbances is formulated on the basis of the sliding mode conplacement, and also for the position tracking control of desired trajectories with low-frequency sine and square waves.

• Structural Engineering and Mechanics
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• 제90권4호
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• pp.403-415
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• 2024

We looked at how the damping qualities of epoxy composites changed when different amounts of graphite nanoplatelets (GNP) were added, from 0% to 6% by weight. A mix of free and forced vibration tests helped us find the key GNP content that makes the damper ability better the most. We also created a Representative Volume Element (RVE) model to guess how the alloys would behave mechanically and checked these models against testing data. An Artificial Neural Network (ANN) was also used to guess how these compounds would react to motion. With proper hyperparameter tweaking, the ANN model showed good correlation (R²=0.98) with actual data, indicating its ability to predict complex material behavior. Combining these methods shows how GNPs impact epoxy composite mechanical properties and how machine learning might improve material design. We show how adding GNPs to epoxy composites may considerably reduce vibration. These materials may be used in industries that value vibration damping.

• Structural Engineering and Mechanics
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• 제89권6호
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• pp.549-556
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• 2024

A serial pendulum dynamic vibration absorber (DVA) was designed to suppress the vibration of two degrees of freedom (Two-DOF) structure model. The optimal DVA parameters are selected using a genetic algorithm (GA) by minimizing the fitness function formulated from the system's frequency response function (FRF). Two fitness function criteria, using one and two target frequency ranges, were utilized to calculate the optimal DVA parameters. The optimized serial pendulum DVA parameters were used to reduce structural vibration under free and forced excitation conditions. The simulation study found that the serial pendulum DVA can effectively reduce the vibration response for a small excitation amplitude. However, the DVA performance decreases for a large excitation amplitude due to the nonlinearity of pendulum motion, and the percentage of vibration response attenuation is smaller than that obtained using a small excitation amplitude.

• Journal of Chest Surgery
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• 제29권9호
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• pp.1017-1022
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• 1996

늑골골절을 입은 환자들은 심한 흉통으로 괴로워하며 이 통증은 기침, 심호흡과 기도세척을 방해하여 결국 무기폐와 호흡부전등을 초래할 수 있다. 통증의 완화는 환자를 편하게 해주고 효과적인 물리요법으로 객담배출을 용이하게한다. 늑골골절 환자에서 경막외 신경차단의 효과를 측정하기 위하여 20명의 환자를 대상으로 경막외 진통제을 투여한 10명은 실험군, 진통제를 근육주사한 10명은 대조군으로 정하 여 통증호소와 운동장애의 정도, 말초동맥혈 산소분압 및 폐기능(FRC, FEVI)의 변화를 입원직후와 경막외 진통제투여 시작후 12, 24시간 및 3일, 5일 그리고 7일째에 각각측정조사 하였다. 신경차단군에서 통증호소와 운동장애의 정도는 감소하였고 동맥혈 산소치는 약간 증가하였으나 의의가 없었으며 FRC와 FEVI는 유의하게 증가하였다. 경막외 신경차단의 부작용은가벼웠으며 쉽게 치료되었다. 위의결과로 저자들은 늑골골절 환자에서 경막외 신경차단에 의한진통법이 동통완화효과와 폐기능 향상에 괄목할만한 효과을 나타내므로 이의 임상적 이용이 바람직하다고 생각한다.

• 대한조선학회논문집
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• 제39권1호
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• pp.73-81
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• 2002

일반적으로, 선박에 탑재되는 장비의 진동문제는 장비자체의 기진력에 의한 진동문제뿐만 아니라 외부기진력인 주기관과 추진기의 기진력이 장비하부 데크를 통하여 장비에 과도 진동을 유발하는 경우가 많다. 따라서 본 연구에서는, 선박에 탑재되는 장비 마운팅 시스템의 진동 성능을 평가할 수 있도록 고유진동해석, 전달율계산, 강제진동해석 등을 수행할 수 있는 프로그램을 개발하였고, 선내 주요기진원과 장비의 공진시 공진회피를 위한 마운트 설계 변경 프로그램과, 그리고 장비 마운트 하부데크의 진동에 의한 장비의 무게중심에서 속도응답이 최소가 되도록, 마운트 강성을 결정하는 최적화 프로그램을 개발하였다.

• The Korean Journal of Pain
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• 제9권1호
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• pp.135-139
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• 1996

Intercostal nerve blockade with local anesthetics has been used extensively in the past to provide pain relief following thoracotomy. Its popularity fell, for a period, probably due to increasing use of epidural analgesia. More recently, interest has focused on intercostal nerve block with the introduction of variously sited catheters. Two epidural catheters were placed under direct vision, in the intercostal spaces just above and below the wound by feeding the catheters posteriorly from the wound edges, superficial to the parietal pleura. Bupivacaine 0.25%. Was infused continuously at a rate of 5 ml/hour through each of the two intercostal catheters. Each catheter was primed with 10 ml/hour through each of the two intercostal catheters. Each catheter was primed with 10 ml of 0.25% bupivacaine. Postoperative vital signs resembled preoperation data. Arterial carbon dioxide pressure ($PaCO_2$) was unchanged and arterial oxygen pressure ($PaO_2$) was increased during two days after surgery because oxygen was administered at 21/min. Forced vital capacities (FVC) and forced expiratory volume in 1 second ($FEV_1$) were decreased the day of operation but restored to preoperative value from second operation day. VAS were increased on operation day but decreased from second operation day. Motion range of arms were not impaired. We concluded that continuous intercostal nerve block through catheters placed during thoracotomy in the adjacent intercostal spaces is a simple and effective method for management of the post-thoracotomy pain.

• 한국전산구조공학회논문집
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• 제13권4호
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• pp.395-404
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• 2000

강제진동을 가한 구조물의 제한된 위치에서 측정한 가속도를 사용하여 손상을 확인하고 평가하는 알고리듬을 개발하였다. 개발된 알고리듬에서는 선형적 구속-비선형 최적화에 의해 최적의 구조변수를 구하여 구조물을 인식하는 시간영역-시스템 인식기법을 사용하였다. 동적운동방정식의 오차를 최소화하도록 최적의 변수를 추정하였으며, 제한된 위치에서 측정된 가속도 자료를 이용하여 손상된 부재를 찾기 위하여 적합적 변수모음법을 적용하였다. 손상은 측정된 가속도의 시간이력에 시간창의 개념을 적용하여 통계적으로 평가하였다. 가속도가 측정된 자유도에서의 변위와 속도는 측정된 가속도를 적분하여 계산하였으며, 미측정 자유도에서는 변위를 추가의 미지변수로 추정하고, 속도와 가속도는 추정된 변위의 차분에 의해 수치적으로 계산하였다. 개발된 알고리듬의 효율성을 검증하기 위하여 트러스에 대한 수치모의실험을 실시하였다. 손상지수의 한계치를 정하고 각 부재에서의 손상가능도를 계산하기 위하여 자료교란법을 적용하였다.

• The Journal of Korean Physical Therapy
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• 제33권4호
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• pp.179-186
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• 2021

Background: Patients with advanced asthma and chronic obstructive pulmonary disease (COPD) have postural deviations such as thoracic hyperkyphosis, forward shoulder posture (FSP) due to an increase in head and cervical protraction, reduced shoulder range of motion and a corresponding increase in scapula elevation and upward rotation. Unlike congenital vertebral kyphosis that are permanent and rigid deformities with bony and other structural deformations which cause respiratory impairment, these deformities in these patients may be more flexible. Since the thoracic hyperkyphosis has been implicated as having adverse health consequences it is necessary to evaluated the relationship between thoracic kyphosis and cardiopulmonary functions of patients with COPD and asthma. Methods: It was a cross-sectional analytical study. Eighty-four eligible patients with COPD and asthma were recruited from the Respiratory Unit, Department of Medicine, Lagos University Teaching Hospital (LUTH), and basic anthropometric parameters, pulmonary parameters, cardiovascular parameters, thoracic kyphosis (Cobb) angle and presence of respiratory symptoms of participants were assessed. Data was analyzed using SPSS version 20. Results: There was no significant correlation between the thoracic kyphosis and selected pulmonary parameters (Forced Expiratory Volume in one second (FEV1, p=0.36), Forced Vital Capacity (FVC, p=0.95), Peak Expiratory Flow Rate (PEFR, p=0.16), Thoracic expansion (TE, p=0.27)/cardiovascular parameters (Systolic Blood Pressure (SBP, p=0.108), Diastolic Blood Pressure (DBP, p=0.17) and Pulse Rate (PR, p=0.93) as well as the respiratory symptoms (SGRQ scores, p=0.11) in all subjects. Conclusion: There was no relationship between thoracic kyphosis and selected pulmonary/cardiovascular parameters as well as respiratory symptoms in patients with COPD and asthma.

• 대한물리의학회지
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• 제14권3호
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• pp.13-20
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• 2019

PURPOSE: Sitting with crossed legs may have an effect on maintaining a healthy body posture and proper functioning of the respiratory system. Thus, this study's objective was to identify whether or not sitting with crossed legs affects the vertebral angle, chest wall mobility, the pulmonary function, and the activity of the respiratory muscles. METHODS: Thirty healthy subjects were recruited for this study (16 males and 14 females). The vertebral angle, chest wall mobility, pulmonary function, and the activity of the respiratory muscle were measured while the subjects sat in the correct posture and these factors were again measured with the subjects seated with their legs crossed. Three-dimensional motion analysis was used to determine the trunk and lumbar vertebral angles. Surface electromyography was employed to measure the sternocleidomastoid, the rectus abdominis, and the external and internal oblique abdominis muscles. A tapeline was utilized to evaluate the subjects' chest wall mobility. Spirometry was assessed to determine the forced vital capacity and forced expiratory volume in one second. Paired t-tests were then performed (p<.05). RESULTS: There were significant differences in the trunk and lumbar flexion angles, the chest wall mobility, the activity of the right external oblique muscle, and the left internal oblique abdominis muscle. However, the difference in pulmonary function did not reach statistical significance. CONCLUSION: A crossed leg posture caused slight thoracic extension and lumbar flexion, which may lead to a decrease of the chest wall mobility and also to an imbalance of the abdominal muscles. Therefore, sitting with a crossed leg posture should be avoided. Yet a crossed leg posture did not have any clinical effect on the pulmonary function of healthy people. It may be necessary to study the effects of sitting with crossed legs over an extended period of time for patients suffering with impaired respiratory function.