• The Journal of Korean Physical Therapy
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• 제19권1호
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• pp.11-22
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• 2007

Purpose: The purpose of this study were to analysis the effect on change of spinal neuron excitability during gait training of hemiplegia patients by the functional electrical stimulation. Methods: Thirty six hemiplegia patients participated in this study. Stimulation conditions of FES were pulse rate 35pps, pulse width $250{\mu}s$, and on-time 0.3 second, treatment hour was 30 min. and treatment period was once a day for five days a week through six weeks. For functional evaluations before and after treatment, Modified Ashworth Scale (MAS), active range of motion (AROM), Hmax threshold, H/Mmax ratio were measured and the following conclusions were obtained. Results: Functional evaluation showed significant changes in experimental group as MAS(p<0.01), AROM(p<0.001), compared to control group. In spinal neuron excitability evaluation, change of Hmax threshold was significantly reduced in both non weight bearing (p<0.001) and bearing condition (p<0.05), H/Mmax ratio was significantly reduced in non weight bearing (p<0.05) and bearing condition (p<0.05). Conclusion: In conclusion, application of FES to hemiplegia patients in recovery stage during gait training improved mitigation of muscular spasticity, balance adjustment and moving ability and it was interpreted that it was caused by mitigation of muscular spasticity by the spinal neuron excitability.

• The Journal of Korean Physical Therapy
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• 제21권2호
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• pp.103-108
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• 2009

Purpose: Electrical stimulation is one of several treatments recommended for RA patients. Electrical stimulation of RA patients, reduces pain, or facilitates joint motion prior to exercises. However, there is still limited evidence on the efficacy of electrical stimulation and thus any conclusions drawn about this method remain controversial. Recently, Microcurrent Electrical Neuromuscular Stimulation (MENS) has received significant attention as a potential method of electrical stimulation. In this study, we investigated the effect of microcurrent treatment in rheumatoid arthritis rat. Methods: Subjects were allocated either to the control group or experimental group, which was subject to microcurrent stimulation. Interleukin-1 expression in the metatarsophlangeal joint and the oedema index in the ankle were used for classification and subsequent evaluation of pathology. Subjects were assessed at 1, 7 and 14 days after inducing rheumatoid arthritis through adjuvant injection. Thirty-six subjects, 18 in each group, were used in this study. Statistical analysis was performed by calculating the differences between the two groups and between each interval assessment. Categorical variables were compared between the two groups with the paired-T test. The one-way ANOVA test was performed to assess changes in ordinal variables. Results: Baseline characteristics were similar in both groups. Statistically significant differences were found between the two groups. The biological marker of pro-inflammatory cytokine and oedema index were decreased in response to this treatment. Conclusion: These data show that treatment of rheumatoid arthritis with a microcurrent stimulation device reduced the oedema index and pro-inflammatory cytokine IL-1.

• 로봇학회논문지
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• 제3권2호
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• pp.81-90
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• 2008

While increasing demand of the service for the disabled and the elderly people, assistive technologies have been developed rapidly. The natural signal of human such as voice or gesture has been applied to the system for assisting the disabled and the elderly people. As an example of such kind of human robot interface, the Soft Remote Control System has been developed by HWRS-ERC in $KAIST^[1]$. This system is a vision-based hand gesture recognition system for controlling home appliances such as television, lamp and curtain. One of the most important technologies of the system is the hand gesture recognition algorithm. The frequently occurred problems which lower the recognition rate of hand gesture are inter-person variation and intra-person variation. Intra-person variation can be handled by inducing fuzzy concept. In this paper, we propose multivariate fuzzy decision tree(MFDT) learning and classification algorithm for hand motion recognition. To recognize hand gesture of a new user, the most proper recognition model among several well trained models is selected using model selection algorithm and incrementally adapted to the user's hand gesture. For the general performance of MFDT as a classifier, we show classification rate using the benchmark data of the UCI repository. For the performance of hand gesture recognition, we tested using hand gesture data which is collected from 10 people for 15 days. The experimental results show that the classification and user adaptation performance of proposed algorithm is better than general fuzzy decision tree.

• 지질공학
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• 제17권4호
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• pp.545-554
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• 2007

자연사면 산사태는 주요 유발인자인 강우나 지진 이외에 토질특성, 지형 및 지질요소 등 다양한 인자의 영향으로 발생될 수 있다. 본 연구지역의 경우 파괴의 시점에 인공구조물이 시공되어 있어 이들과 사면붕괴와의 관련성을 밝히는 것은 매우 의미가 있다. 이를 위해 원지반의 물성을 추정하여 자연사면 자체의 붕괴에 대한 취약성을 파악하고 구조물에 의해 변화된 지반에 대한 불안정성을 비교하여 붕괴원인을 살펴보았다. 현장조사와 실내시험으로 원지반과 성토지반의 물성을 구하였고, 지구물리탐사를 통해 추정된 파괴면의 심도를 이용하여 지하수위 변화에 따른 2차원과 3차원 한계평형해석을 각각 수행하였다. 해석결과는 지반의 토질특성과 강도정수에 상관없이 비슷한 안전율을 보였고, 지하수위는 만수위시 불안정해지는 것으로 나타났다.

• Applied Microscopy
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• 제42권2호
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• pp.95-103
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• 2012

연잎효과는 연꽃의 잎에서 규명된 현상으로 표피세포에서 기원하는 미세구조에 의해 물방울이 잎 표면이나 내부조직에 침투하지 않고 경사면으로 흘러내리며 표면 위 먼지나 이물질을 함께 떨어지게 한다. 잎 표면을 항상 깨끗한 상태로 유지하는 자기정화 능력인 연잎효과에 대해서는 여러 영역에서 연구되고 다방면으로 응용되고 있으나 구조적인 측면에서 연잎을 생장단계별 또는 표피조직 부위별로 비교 조사한 연구는 거의 없는 실정이다. 이에 본 연구에서는 연잎과 줄기를 대상으로 생장단계별, 부위별 표피조직의 미세 표면구조를 연구하여 연잎효과 표면 특성을 조사하였다. 본 연구에서 조사된 연잎효과는 미세돌기와 왁스결정체가 발달한 잎의 상피조직에서만 나타나고, 왁스결정체만 발달한 하피 및 줄기의 표피조직에서는 확인되지 않았다. 이는 미세돌기의 발달이 연잎효과를 나타내는데 가장 중요한 요인이고, 왁스결정체가 돌기표면 위에 축적되면 연잎효과는 더 증가하는 것으로 밝혀졌다.

• 한국게임학회 논문지
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• 제17권6호
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• pp.113-120
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• 2017

최근 가상현실 기술의 발전으로 가상의 3D 객체와 자연스러운 상호작용이 가능하도록 하는 사용자 친화적인 손 제스처 인터페이스에 대한 연구가 활발히 진행되고 있다. 그러나 대부분의 연구는 단순하고 적은 종류의 손 제스처만 지원되고 있는 실정이다. 본 논문은 가상환경에서 3D 객체와 보다 직관적인 방식의 손 제스처 인터페이스 방법을 제안한다. 손 제스처 인식을 위하여 먼저 전처리 과정을 거친 다양한 손 데이터를 이진 결정트리로 1차 분류를 한다. 분류된 데이터는 리샘플링을 한 다음 체인코드를 생성하고 이에 대한 히스토그램으로 특징 데이터를 구성한다. 이를 기반으로 학습된 MCSVM을 통해 2차 분류를 수행하여 제스처를 인식한다. 본 방법의 검증을 위하여 3D 블록을 손 제스처를 통하여 조작하는 'Virtual Block'이라는 게임을 구현하여 실험한 결과 16개의 제스처에 대해 99.2%의 인식률을 보였으며 기존의 인터페이스보다 직관적이고 사용자 친화적임을 알 수 있었다.

• 한국통신학회논문지
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• 제23권4호
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• pp.1087-1099
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• 1998

내용 기반 부호화에서는 장면내의 객체를 독립된 단위로 부호화를 수행하므로, 객체의 모양, 질감, 움직임등의 정보가 중요한 부호화 대상이 된다. 특히, 객체의 모양정보를 나타내는 윤곽선은 전체 정보량의 큰 부분을 차지하면서 주관적 화질에 커다란 영향을 끼치므로 부호화시 심각한 왜곡이 발생하지 않도록 해야한다. 본 논문에서는 윤곽선 부호화를 위해 윤곽선 다각근사화와 이때 발생하는 오차신호를 보상하기 위해 이를 변환 부호화하는 방법을 제안한다. 제안하는 방법에서는, 윤곽선의 다각 근사화시 발생하는 윤곽선의 단편들이 완만한 곡선의 형태를 갖고 오차신호의 양 끝점이 0이라는 특징을 고려해서, 르장드르 다항식에 기반한 새로운 기저를 설계해서 오차신호를 변환한다. 제안한 방법은, 원, 타원 등의 합성영상에 적용했을 경우 이산 여현 변환, 이산 정현 변환 등에 비해 변환부호화 이득면에서 전반적으로 우수한 결과를 얻었고, 자연영상에 적용했을 경우에도 이산 여현보다 우수한 결과를 얻었으며, 이산 정현변환과 대등한 결과를 얻었다.

• 제어로봇시스템학회논문지
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• 제22권10호
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• pp.853-858
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• 2016

Cooperation and collaboration with robots are key functions of robotic utility that are currently developing. Thus, robots should be safe and resemble human beings to cope with these needs. In particular, dual-arm robots that mimic human kinetics are becoming the focus of recent industrial robotics research. Their size is similar to the size of a human adult; however, they lack natural, human-like motion. One of the critical reasons for this is the shoulder complex. Most recent dual-arm robots have only 2 degrees of freedoms (DOFs), which significantly limits the workspace and mobility of the shoulders and arms. Therefore, a redundant shoulder complex could be very important in new developments that enable new capabilities. However, constructing a kinematically redundant shoulder complex is difficult because of spatial constraints. Therefore, we propose a novel, redundant shoulder complex for a human-like robot that is driven by flexible wire tendons. This kinematically redundant shoulder complex allows human-like robots to move more naturally because of redundant DOFs. To control the proposed shoulder complex, a hybrid control scheme is used. The positioning precision has also been considered, and the ability of the shoulder complex to perform several human-like motions has been verified.

• Structural Engineering and Mechanics
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• 제42권5호
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• pp.715-728
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• 2012

This paper deals with determining the fundamental frequency of tall buildings that consist of framed tube, shear core, belt truss and outrigger systems in which the framed tube and shear core vary in size along the height of the structure. The effect of belt truss and outrigger system is modeled as a concentrated rotational linear spring at the belt truss and outrigger system location. Many cantilevered tall structures can be treated as cantilevered beams with variable cross-section in free vibration analysis. In this paper, the continuous approach, in which a tall building is replaced by an idealized cantilever continuum representing the structural characteristics, is employed and by using energy method and Hamilton's variational principle, the governing equation for free vibration of tall building with variable distributed mass and stiffness is obtained. The general solution of governing equation is obtained by making appropriate selection for mass and stiffness distribution functions. By applying the separation of variables method for time and space, the governing partial differential equation of motion is reduced to an ordinary differential equation with variable coefficients with the assumption that the transverse displacement is harmonic. A power-series solution representing the mode shape function of tall building is used. Applying boundary conditions yields the boundary value problem; the frequency equation is established and solved through a numerical process to determine the natural frequencies. Computer program has been developed in Matlab (R2009b, Version 7.9.0.529, Mathworks Inc., California, USA). A numerical example has been solved to demonstrate the reliability of this method. The results of the proposed mathematical model give a good understanding of the structure's dynamic characteristics; it is easy to use, yet reasonably accurate and suitable for quick evaluations during the preliminary design stages.

• 한국운동역학회지
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• 제20권2호
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• pp.239-243
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• 2010

The putting stroke accounts for 40~50% of total stroke for a golf rounding and most golfers have difficulties on the puting. Studies for the putting stroke have been conducted by analyzing various factors such as kinematics, kinetics, psychologic and physiologic parameters. A lot of devices were developed to support the studies. However there was no appropriate method to measure the position of the ball quantitatively. In this study, we developed a new measurement system to measure and evaluate the putting result. The developed system uses a USB camera to take the 2-dimensional image of the surface including the hole cup at the center of the image and the ball. The position of the ball is extracted as a set of distance and angle in polar coordinate system. We evaluated the new system with an indoor set-up for putting experiments and the system provided accurate measurement results. The proposed system can be combined with the other measurement systems such as 3D motion capture system and force plate without any restriction.