• Journal of Institute of Control, Robotics and Systems
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• v.17 no.8
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• pp.814-823
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• 2011

Nowadays many neurological diseases such as stroke and Parkinson diseases are continually increasing. Orthotic devices as well as exoskeletons have been widely developed for supporting movement assistance and therapy of patients. Robotic knee orthosis can compensate stiff-knee gait of the paralyzed limb and can provide patients consistent assistance at wearable environments. With keeping a robotic orthosis wearable, however, it is not easy to develop a compact and safe actuator with fast rotation and high torque for consistent supports of patients during walking. In this paper, we propose a novel kinematic model for a robotic knee orthosis to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The suggested kinematic model is composed of a hamstring device with a slide-crank mechanism, a quadriceps device with five-bar/six-bar links, and a patella device for knee covering. The quadriceps device operates in five-bar links with 2-dof motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The kinematics and velocity/force relations are analyzed for the quadriceps and hamstring devices. Finally, the adequate actuators for the suggested kinematic model are designed based on normal gait requirements. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.71-80
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• 2016

The main goal of this study is to develop a multi-metric fishway assessment model (M_m-FA) and evaluate the efficiency of fishway. The M_m-FA model has three major fishway components with nine metrics: structural characteristics, hydraulic/hydrologic features, and biological attributes. The model was developed for diagnosing and assessing fishway efficiency and tested to Juksan Weir at the Yeongsan River Watershed. Structural characteristics of fishway included slope of the fishway (M₁), ratios of fishway width to stream width (M₂), and the proportion of orifice clogging and orifice size (M₃). Hydraulic/hydrologic characteristics included depth of fishway entrance head (M₄), depth of exit tail (M₅), and current velocity of inner fishway (M₆). Biological characteristics included fish species ratio of inner fishway to upper-lower weir (M₇), fish length distribution (M₈), and the proportion of migratory fish species to the total number of species (M₉). Overall, the assessment of fishway efficiency showed the total score of the M_m-FA model was 25 in the Juksan Weir, indicating "good condition" by the criteria of the five-level classification system. The M_m-FA model may be used as a key tool for the assessment of fishway efficiency, especially on the 16 weirs constructed for the "Four Rivers Restoration Project" after a partial calibration of M_m-FA model.

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.106-115
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• 2010

This study described the stability of riprap, which was examined by a two-dimensional physical model of a scattered riprap submarine breakwater. Artificial reef structures made of scattered riprap are used like artificial intertidal zone structures as waterfront seaside structures. To prevent topography change in such an artificial intertidal zone the energy is reduced at the scattered riprap submarine breakwater by intercepting high waves. The breaking waves are converted into flow on the front surface slope of the submarine breakwater, which follows the upper part of the artificial intertidal zone. Because of this phenomenon of resisting water flow, it is very important to calculate the required weight of the riprap to maintain its stability. The results of a physical model can be abstracted as shown below. First, distribute the wave breaking types occurring on the front surface slope of the submarine breakwater and arrange it in relation to the movement of riprap. Second, using the hydraulic phenomenon that occurs at the depth of the scattered riprap submarine breakwater, propose a calculation formula for the velocity distribution showing the influence on the stability of the riprap. Third, propose and compare values, which can be obtained by experiments and calculations for riprap stability on the front surface of the artificial intertidal zone. Fourth, calculate the required weight for riprap stability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.1
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• pp.215-222
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• 2017

An active synthetic aperture sonar mounted on small UUV is generated various trajectory disturbances in the traveling path by the influence of external underwater environments. That is the phase mismatch occurs in the synthetic aperture processing of the signals reflected from seabed objects and fetches the detection performance decreases. In this paper, we compensated deteriorated images by the active SAS autofocus processing using DPC and analyzed the effects of detection performance when the periodic trajectory disturbances occur in the side direction at a constant velocity and straight movement of UUV. Through simulations, the deteriorated images according to the periodic disturbance magnitudes and period variations in the platform were compensated using difference phases processing of the overlapping displaced phase centers on the adjacent transmitted ping signals, and we conformed the improved performance characteristics of azimuth resolution and detection images at 3dB reference point.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11C
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• pp.1071-1076
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• 2006

In this paper, we develop face and hand tracking for sign language recognition system. The system is divided into two stages; the initial and tracking stages. In initial stage, we use the skin feature to localize face and hands of signer. The ellipse model on CbCr space is constructed and used to detect skin color. After the skin regions have been segmented, face and hand blobs are defined by using size and facial feature with the assumption that the movement of face is less than that of hands in this signing scenario. In tracking stage, the motion estimation is applied only hand blobs, in which first and second derivative are used to compute the position of prediction of hands. We observed that there are errors in the value of tracking position between two consecutive frames in which velocity has changed abruptly. To improve the tracking performance, our proposed algorithm compensates the error of tracking position by using adaptive search area to re-compute the hand blobs. The experimental results indicate that our proposed method is able to decrease the prediction error up to 96.87% with negligible increase in computational complexity of up to 4%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.377-386
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• 2008

In this paper, a new handover management scheme has been proposed to reduce handover latency and to support fast handover without packet losses, so that it may be applicable to the wireless mobile Internet system such as IPv6-based WiBro system. To minimize the handover latency in processing of movement detection, we propose the handover management scheme which simplifies the handover message exchanging procedure between mobile subscriber station (MSS) and network by integrating layer 2 and layer 3 handovers efficiently based on the layer2 information. To reduce the processing delay from new care-of-address (NCoA) configuration during handover, we propose that NCoA is created, distributed and managed by new access control router (NACR). In addition, in order to minimize the packet transmission delay and eliminate the packet losses, the proposed scheme employs a crossover router (CR) which is upper network located over PACR and NACR and employs the packet buffering for MSS. The simulation study shows that the proposed scheme achieves loss-free packet delivery and low latency in the environment of narrow overlapped cell area or high velocity of the MSS, comparing the performance with the conventional schemes.

• Physical Therapy Korea
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• v.10 no.4
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• pp.1-15
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• 2003

본 연구는 슬관전 신전 직전에 수행된 선행 슬관절 굴곡이 슬관절 신전근의 최대 근력발생 및 근육 활성도(activation)에 미치는 영향을 알아보기 위하여 실시되었다. 16명의 정상인이 Cybex II 등속운동기구에서 3가지 다른 운동 속도($100^{\circ}/s$, $200^{\circ}/s$, $300^{\circ}/s$)와 2가지 다른 근육 활성 조건(선행부하가 없는 조건과 선행부하 조건)에서 슬관절의 최대 신전을 수행하였다. 연구대상자들에게 선행부하 없는 조건에서는 $90^{\circ}$ 슬관절 굴곡 상태에서 $0^{\circ}$까지 최대 신전을 수행하도록 하였고, 선행부하 조건에서는 구심성 슬와부 근육의 구심성 수축으로 $0^{\circ}$에서 $110^{\circ}$까지 굴곡한 후, 다시 $0^{\circ}$까지 최대 신전을 하도록 요구하였다. 종속변인으로는 내측광근과 외측광근의 최대 근전도와 최대 신전근력을 측정하였다. 실험 결과 최대 근전도와 최대 근력 모두 선행부하 조건에서 높게 나타났으며, 운동 속도가 증가함에 따라 최대 근력은 감소하는 전형적인 최대 근력-운동속도 상관법칙이 본 실험에서도 나타났다. 또한 운동속도와 전환속도 간의 간섭이 없는 것으로 나타나, 슬관절 신전근에 선행부하(preloading)를 가하는 것이 최대 근력-운동속도 상관법칙(force-velocity relation)에 영향을 미치지 못하는 것으로 해석되었다. 선행부하로 인해 증가된 최대 근력 및 근 활성도의 증가는 주로 신경촉진에 의한 것으로 해석된다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.2
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• pp.318-323
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• 2013

For fast and accurate motion of 6-axis articulated robot, more noble motion control strategy is needed. In general, the movement strategy of industrial robots can be divided into two kinds, PTP (Point to Point) and CP (Continuous Path). Recently, industrial robots which should be co-worked with machine tools are increasingly needed for performing various jobs, as well as simple handling or welding. Therefore, in order to cope with high-speed handling of the cooperation of industrial robots with machine tools or other devices, CP should be implemented so as to reduce vibration and noise, as well as decreasing operation time. This paper will realize CP motion (especially joint-linear) blending in 3-dimensional space for a 6-axis articulated (lab-manufactured) robot (called as "RS2") by using LabVIEW$^{(R)}$ (6) programming, based on a parametric interpolation. Another small contribution of this paper is the proposal of motion blending simulation technique based on Recurdyn$^{(R)}$ V7 and Solidworks$^{(R)}$, in order to figure out whether the joint-linear blending motion can generate the stable motion of robot in the sense of velocity magnitude at the end-effector of robot or not. In order to evaluate the performance of joint-linear motion blending, simple PTP (i.e., linear-linear) is also physically implemented on RS2. The implementation results of joint-linear motion blending and PTP are compared in terms of vibration magnitude and travel time by using the vibration testing equipment of Medallion of Zonic$^{(R)}$. It can be confirmed verified that the vibration peak of joint-linear motion blending has been reduced to 1/10, compared to that of PTP.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.232-237
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• 2013

A newly developed fall detection algorithm using the HMM (Hidden Markov Model) extracted from the video is introduced. To distinguish between the fall from personal difference fall pattern or the normal activities of daily living (ADL), HMM machine learning algorithm is used. For getting fall feature vector of video, the motion vector from the optical flow is applied to the PCA (Principal Component Analysis). The combination of the angle, ratio of long-short axis, velocity from results of PCA make the new fall feature parameters. These parameters were applied to the HMM and the results were compared and analyzed. Among the newly proposed various kinds of fall parameters, the angle of movement showed the best results. The results show that this parameter can distinguish various types of fall from ADLs with 91.5% sensitivity and 88.01% specificity.

• PNF and Movement
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• v.15 no.3
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• pp.353-360
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• 2017

Purpose: This study aimed to measure static balance of low back pain patients while one-leg standing in abdominal compression belts. Methods: The study included 40 adult males and females at J university, divided into a low back pain patient group and a normal group through the Oswestry disability questionnaire (ODQ). The subjects were instructed to hold a one-leg standing posture for 15 seconds on a balance measurement plate while wearing an abdominal compression belt. Shifting distance (0.1 cm), mean velocity (cm/s), pressure, and contact area were analyzed using BioRescue (BioRescue, RMINGEIEIRIE, Rodez, France). The average value was used to measure the result 3 times for each condition. Results: Both normal and low back pain groups significantly decreased in the speed of sway while wearing the abdominal compression belt. Furthermore, the pressure of the center of motion significantly decreased in the low back pain groups while wearing abdominal compression belt. However, there were no significant differences in the speed of sway or the pressure of center of motion between groups after wearing the abdominal pressure belt. Conclusion: These results suggest that abdominal compression belts are one option for improving balance temporarily. However, balance after wearing abdominal compression vests depends on onset of back pain, age, and symptoms of pain in the groups with low back pain. Further research is needed to investigate muscle activity, dynamic balance, and the effect of the period of wearing abdominal compression belts in the variety of low back pain patients.