• 대한의용생체공학회:의공학회지
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• 제34권4호
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• pp.212-217
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• 2013

Falling is one of the major public problems to the elderly, resulting in limitations of daily living activities. It can be induced by the functional loss of the balance ability and muscle strength in the elderly. It has been, however, not well investigated to suggest an effective methodology improving the balance ability and muscle strength for the prevention of the falling due to lack of information about the characteristics of the balance and muscle activations responded to the dynamic motions. The aim of the current study is, therefore, to identify the characteristics of the balance and muscle activations responded to the dynamic motions in Anterior-Posterior(AP) and Medial Lateral(ML) directions. For that, a motion capture system with eight infrared cameras, surface electromyogram system and Wii Fit system with a customized variable unstable base were used and kinematic and kinetic data obtained from the systems were analyzed for five healthy male($24.8{\pm}3.3years$, $177.4{\pm}2.0cm$, $73.9{\pm}12.9kg$, $23.5{\pm}4.0kg/m$). The results showed that the characteristics of the balance and muscle activations were differently responded to between the dynamic motions in Anterior-Posterior(AP) and Medial Lateral(ML) directions. These findings may indicate that customized dynamic motions should be applied to the training of the balance ability and muscle strength for the effective prevention of the falling. This study may be meaningful to providing basic information to establish a guideline improving effectively the balance ability and muscle strength.

• Clinics in Shoulder and Elbow
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• 제1권2호
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• pp.242-249
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• 1998

Stiffness of the elbow joint is relatively common after trauma, ectopic ossification, bum, postoperative scar, and etc. Mild flexion deformity can be reduced by use of active or passive motion exercise, dynamic sling, hinged distractor device, or turnbuckle orthosis. But these methods have disadvantages of difficulty in gaining acceptable range of motion only with stretching exercise, re-contracture after conservative managements and poor results that flexion contracture remained. The common described operative exposures for treatment of the stiff elbow are anterior, lateral, posterior, and medial approach. Through Anterior, lateral and medial approach each has not access to all compartments of the elbow. But, posterior approach has benefits that access to posterior, medial and lateral aspects of the elbow and as needed, fenestration to the olecranon fossa that produces a communication between the anterior and posterior compartments of the elbow are possible. From June 1991 through April 1997, 11 patients who had posttraumatic stiff elbow, were treated with debridement arthroplasty through the posterior approach. The purpose of this study are to introduce technique of the debridement arthroplasty and to evaluate final outcomes. With regarding to preoperative pain degree, mild degree matches to 3 cases, moderate to 3 cases, and severe to 2 cases. In preoperative motion, flexion was average 85° and extension was 30°. Postoperatively nine patients had got the complete relief of pain and two patients continued to have mild pain intermittentely. Postoperative flexion improved to 127° and extension to 2°, so that elbow flexion had improved by an average of 42° and elbow extension by 28°. On the objective scale all patients had good or excellent results and they all felt that they were improved by operation. Debridement arthroplasty is one of excellent procedures for the intractable stiff elbow if it is not unstable or it has not incongrous. But it need a meticulous operative technique and a well-programmed rehabilitation.

• 한국산학기술학회논문지
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• 제20권5호
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• pp.621-626
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• 2019

자동차의 과도한 차체 운동과 조종 불안정성을 유발하는 대표적인 외란 입력으로는 운전자에 의해 가해지는 조향 핸들 조작이다. 급격하고 과도한 핸들 조작은 SUV 차량처럼 기하학적 및 동역학적 특성에 따라 차량 전복 현상도 발생시킬 수 있다. 본 연구에서는 이에 대응할 수 있는 제어 시스템의 구조화에 대하여 다음과 같이 기초 연구를 수행하였다. 운전자 조종으로 유발되는 횡방향 거동에 대한 수학적 모델링을 수행하고, 이를 토대로 차체 운동을 제어할 수 있는 제어기를 설계하였다. 파라미터 불확실성으로 인한 모델링 오차에 대해 강건한 제어 성능을 확보하기 위하여 $H_{\infty}$ 알고리즘을 적용하였다. 비 연성화된 1/4 차량을 기반으로, 차체에 작용하는 모우멘트에 상응하는 동적 부하를 모사할 수 있는 모델을 제시하였다. 동적 시뮬레이션을 수행하여 부하 모사 모델의 타당성을 파악하였다. 차체- 차축- 서스펜션- 타이어로 조합되는 1/4 실험 차량 장치와 부하 모사 모듈, 서스펜션 제어 모듈 및 Hils 기술을 적용하는 차체 거동 제어 시스템에 대한 프레임워크를 제안하였다.

• The Journal of Korean Physical Therapy
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• 제34권3호
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• pp.91-97
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• 2022

Purpose: This study investigated the short-term effectiveness of extracorporeal shock wave therapy (ESWT) on pain, the ankle instability, the ankle function, dorsiflexion range of motion (ROM), and dynamic balance in patients with chronic ankle instability (CAI). Methods: Eighteen participants were divided into an experimental (n=9) and control group (n=9). The ESWT in the experimental group was applied to the lateral collateral ligament in combination with the tibialis anterior whereas the ESWT was applied to the lateral collateral ligament of the ankle alone in the control group. Pain, the ankle instability, the ankle function, dorsiflexion ROM, and dynamic balance were measured using the Visual analog scale, Cumberland ankle instability tool, American Orthopedic Foot and Ankle Society ankle-hindfoot score, weight-bearing lunge, and Y-balance test, before and after ESWT intervention. Results: Significant interactions (group × time) and time effects were observed in the dorsiflexion ROM and dynamic balance. Bonferroni's post-hoc analysis showed that the experimental group revealed a more significant change in dorsiflexion ROM and dynamic balance than the control group. There was a significant time effect in the pain, the ankle instability, and the ankle function, but no significant interaction (group × time) was observed. Conclusion: The ESWT could improve the pain, ankle instability, ankle function, dorsiflexion ROM, and dynamic balance in patients with CAI. Furthermore, the ESWT combined with lateral ankle ligaments and tibialis anterior more improves the dorsiflexion ROM and dynamic balance.

• 전기학회논문지
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• 제57권3호
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• pp.390-397
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• 2008

Permanent Magnet Linear Synchronous Motor (PMLSM) has high efficiency, high energy density, and high control-ability. But, the detent force always is produced by the structure of slot-teeth. There are the disadvantages such as noise and vibration of the apparatuses are induced and the control ability is curtailed because detent force acts as thrust ripple. Therefore, the detent force reduction is an essential requirement in PMLSM. Generally, the method, skewing permanent magnet or slot-teeth, is used to reduce the detent force. But the thrust is decreased at the same time. If permanent magnet is skewed, the lateral force which operates as the perpendicular direction of skew direction is generated in linear guide of PMLSM. So, V-skew model is proposed for the reduction of lateral force. The lateral force acts as braking force in linear motion guide, and it has bad influence to the characteristics of PMLSM. However, these problems will not be solved by 2-dimensional Finite Element Analysis (FEA). So, in this paper 3-dimensional FEA is applied to analyze the PMLSM where permanent magnet is skewed and has overhang. The detent force and thrust characteristics considering skew and overhang effects of permanent magnet are analyzed by 3-dimensional FEA and the results are compared with experimental values to verify the propriety of analysis.

• Wind and Structures
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• 제11권2호
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• pp.153-178
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• 2008

Based on the empirical formulas for power spectra of generalized modal forces and local fluctuating wind forces in across-wind and torsional directions, the wind-induced lateral-torsional coupled response analysis of a representative rectangular tall building was conducted by setting various parameters such as eccentricities in centers of mass and/or rigidity and considering different torsional to lateral stiffness ratios. The eccentricity effects on the lateral-torsional coupled responses of the tall building were studied comprehensively by structural dynamic analysis. Extensive computational results indicated that the torsional responses at the geometric center of the building may be significantly affected by the eccentricities in the centers of mass and/or rigidity. Covariance responses were found to be in the same order of magnitude as the along-wind or across-wind responses in many eccentricity cases, suggesting that the lateral-torsional coupled effects on the overall wind-induced responses can not be neglected for such situations. The calculated results also demonstrated that the torsional motion contributed significantly to the total responses of rectangular tall buildings with mass and/or rigidity eccentricities. It was shown through this study that the framework presented in this paper provides a useful tool to evaluate the wind-induced lateral-torsional coupled responses of rectangular buildings, which will enable structural engineers in the preliminary design stages to assess the serviceability of tall buildings, potential structural vibration problems and the need for a detailed wind tunnel test.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.504-507
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• 2011

The inertial migration of a two-dimensional elastic capsule in a channel flow was studied over the Reynolds number range $1{\leq}Re{\leq}100$. The lateral migration velocity, slip velocity, and the deformation and inclination angle of the capsule were investigated by varying the lateral position, Reynolds number, capsule-to-channel size ratio(${\lambda}$), membrane stretching coefficient(${\Phi}$), and membrane bending coefficient(${\gamma}$). During the initial transient motion, the lateral migration velocity increased with increasing Re and ${\lambda}$ but decreased with increases in ${\Phi}$, ${\gamma}$ and the lateral distance from the wall. The initial behavior of the capsule was influenced by variation in the initial lateral position ($y_0$), but the equilibrium position of the capsule was not affected by such variation. The balance between the wall effect and the shear gradient effect determined the equilibrium position. As Re increased, the equilibrium position initially shifted closer to the wall and then moved towards the channel center. A peak in the equilibrium position was observed near Re=30 for ${\gamma}=0.1$, and the peak shifted to higher Re as ${\gamma}$ increased. Depending on the lateral migration velocity, the equilibrium position moved toward the centerline for larger ${\gamma}$ but moved toward the wall for larger ${\Phi}$ and ${\gamma}$.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.718-723
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• 2003

The acceptance test of KTX has been performed in Korea. During the test lateral vibration of carbody over the accepted value called sway was found. Many activities have been taken to find the cause of the vibration and the counter-measure. KTX has 20 car trainset formation whose trailer cars are linked by articulate bogies. So this study is performed to see the effects of long trainset formation on vehicle dynamics and the train stability by 16 car vehicle model. Firstly the reliable vehicle model which shows well the tendencies appeared in the tests on the high speed test line is required to find the cause of lateral vibration and the countermeasure. Vehicle model was made for the analysis with VAMPIRE. The analysis results show that secondary air spring lateral stiffness is the most significant parameter to cause carbody lateral vibration. Mode analysis results show that the least damped mode shape is similar to the vibration pattern shown in the tests that the amplitude of the motion increases along the train set and decreases in the tail part. The lateral vibration was appeared at the speed range between 100km/h and 200km/h and disappeared at the low speed and the high speed.

• 한국철도학회논문집
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• 제6권2호
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• pp.122-128
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• 2003

The acceptance test of KTX has been performed in Korea. During the test, lateral vibration of carbody over the accepted value called sway was found. Many activities have been taken to find the cause of the vibration and the counter-measure. KTX has 20 car trainset formation whose trailer cars are linked by articulate bogies. So this study is performed to see the effects of long trainset formation on vehicle dynamics and the train stability by 16 car vehicle model. Firstly the reliable vehicle model which shows well the tendencies appeared in the tests on the high speed test line is required to find the cause of lateral vibration and the countermeasure. Vehicle model was made for the analysis with VAMPIRE. The analysis results show that secondary air spring lateral stiffness is the most significant parameter to cause carbody lateral vibration. Mode analysis results show that the least damped mode shape is similar to the vibration pattern shown in the tests that the amplitude of the motion increases along the train set and decreases in the tail part. The lateral vibration was "appeared at the speed range between 100km/h and 200km/h and disappeared at the low speed and the high speed.

• 대한정형도수물리치료학회지
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• 제14권2호
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• pp.68-77
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• 2008

Purpose : The purpose of this study was to investigate effects of movement with mobilization(MWM) and stabilization exercise on pain and range of motion of patients with acute low back pain. Methods : The subjects were consisted of 24 patients who had non specific acute low back pain. All subjects randomly assigned to the MWM group and the stabilization exercise group. The MWM group received sustained natural apophyseal glides(SNAGs) with modality treatment and stabilization exercise group received stabilization exercise with modality treatment. The remodified schober test(RST) was used to measure forward flexion and lateral flexion range of motion of lumbar segment. Visual Analogue Scale(VAS) was used to measure subjective pain level of the patients. The Oswestry Low Back Pain Disability Scale was used to measure functional disability level of the patients. Results : The lumbar flexion range of motion of MWM group was significantly increased compared with stabilization exercise group(p<.01). The range of motion of lumbar segment of MWM group was significantly decreased compared with stabilization exercise group(p<.01). The left lateral flexion range of motion of lumbar of MWM group was significantly decreased compared with stabilization exercise group(p<.05). The right lateral flexion range of motion of lumbar of MWM group was significantly decreased compared with stabilization exercise group(p<.05). The VAS of both MWM group and stabilization exercise group was significantly decreased(p<.001). The Oswestry Low Back Pain Disability Scale of stabilization exercise group was significantly increased compared with mobilization group(p<.001). Conclusion : In the result of this study, mobilization with movement and stabilization exercise had significant difference on pain and flexibility of patients with acute low back pain.