• Journal of the Korean Society of Physical Medicine
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• v.2 no.2
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• pp.151-159
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• 2007

Purpose : The purpose of the study was to investigate the effect of cold application on knee joint in rats induced by osteoarthritis. Methods : Osteoarthritis was induced in female Sprague-Dowley rats by injecting into articular cavity of knee joint with 4% Kaolin, 2% carrageenan. Rats were divided randomly into the control and MES applicated group. The Experimental group was applicated MES in rat knee joint for 30 minutes. Results : Recovery of articular cartilage surface and thickness of articular cartilage increased after MES application. And chondrocytes were distributed widely throughout the cartilage matrix. The physical effects of Microcurrent Electrical Stimulation. Decrease in blood flow. Delay of neurotransmitter velocity Decrease in metabolism activity and inhibit the progress of the infection. Decrease in pain and muscle rigidity, inhibition of circulation Conclusion : This study shows that MES application affects articular cartilage recovery in osteoarthritis.

• Archives of Reconstructive Microsurgery
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• v.6 no.1
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• pp.96-102
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• 1997

The gracilis that is frequently used as a donor of free muscle trasfer is appropriate in the muscular shape and vascular position. This muscle is belonged to the second type of muscle group by the classification of the pattern of muscular nutrient vessel. The adductor branch or first perforating branch of deep femoral artery which supplies the proximal 1/3 of this muscle is a dominant one and this is used for the microscopic anastomosis of muscle or musculocutaneous flap. The minor vascular pedicles which enter the distal 1/3 of this of this muscle are branches of the superficial femoral artery and it is 0.5mm in diameter, 2cm in length with two venae comitantes. These minor pedicles supplies distal half of the gracilis muscle. This island musculocutaneous flap using distal vascular pedicle can be used to cover the defect of soft tissue around the distal femoral supra-condylar area, knee joint and proximal tibial condyle area which cause limitation of motion of knee joint, or in the cases that usual skin graft is impossible. The important operative procedure is as follows; The dissection is carried proximally and distally and the entire gracilis muscle including proximal and distal pedicle is completely dissected. After temporary blocking of the proximal vascular pedicle, the adequate muscle perfusion by the distal pedicle is identified and it is rotated to the recipient site around knee joint. The advantages of this procedure are simple, no need of microscopic vascular anastomoses and no significant functional loss of donor site. Especially in the cases of poor condition of the recipient vessel, this procedure can be used effectively. From 1991 to 1996, we performed 4 cases; complete survival of flap in 3 cases and partial survival of flap with partial necrosis in 1 case. This procedure is though to be useful in the small sized soft tissue defect of distal femoral supra-condylar area, knee joint and proximal tibial condylar area, especially in the defect of anterior aspect which expected to cause limitation of motion of knee joint due to scar contracture. But the problems of this procedure are the diameter of distal vascular pedicle is small and the location of distal vascular pedicle is not constant. To reduce the failure rate, identify the muscular perfusion of distal vascular pedicle after blocking the proximal pedicle, or strategic delay will be helpful.

• ETRI Journal
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• v.26 no.6
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• pp.622-634
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• 2004

In this paper, we discuss the design problem and the robustness of space-frequency trellis codes (SFTCs) for multiple input multiple output, orthogonal frequency division multiplexing (MIMO-OFDM) systems. We find that the channel constructed by the consecutive subcarriers of an OFDM block is a correlated fading channel with the regular correlation function of the number and time delay of the multipaths. By introducing the first-order auto-regressive model, we decompose the correlated fading channel into two independent components: a slow fading channel and a fast fading channel. Therefore, the design problem of SFTCs is converted into the joint design in both slow fading and fast fading channels. We present an improved design criterion for SFTCs. We also show that the SFTCs designed according to our criterion are robust against the multipath time delays. Simulation results are provided to confirm our theoretic analysis.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.869-872
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• 2001

Blind identification and equalization of communication channel is important because it does not need training sequence, nor does it require a priori channel information. So, we can increase the bandwidth efficiency. The linear prediction error method is perhaps the most attractive in practice due to the insensitive to blind channel estimator and equalizer length mismatch as well as for its simple adaptive algorithms. In this paper, we propose method for fractionally spaced blind equalizer with arbitrary delay using one-step forward prediction error filter from second-order statistics of the received signals for SIMO channel. Our algorithm utilizes the forward prediction error as training sequences for data estimation and desired signal for channel estimation.

• Journal of Yeungnam Medical Science
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• v.16 no.1
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• pp.1-9
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• 1999

Avascular necrosis of the femoral head is a debilitating disease that leads to destruction of tho hip joint in patients who are in the third, fourth, or fifth decade of life. The total societal cost is so high because these patients are generally young, hold jobs, and have a considerable life expectancy. Therefore, we have to delay or eliminate the need for total hip replacement as possible as we can. The purpose of this review is to provide a current perspective of avascular necrosis of the femoral head.

• Transactions of The Korea Fluid Power Systems Society
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• v.1 no.1
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• pp.17-22
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• 2004

The goal of this paper is to improve the position control performance of pneumatic rotary actuator with variable brake using Magneto-Rheological Fluid. The air compressibility and the lack of damping of the pneumatic actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. In this study, a variable rotary brake comprising Magneto-Rheological Fluid is equipped to the joint of a pneumatic manipulator. Experiments of step response have proved that the transient response of the manipulator could be improved compared with that of the conventional control algorithm by using a phase plane switching control algorithm.

• International Commerce and Information Review
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• v.10 no.1
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• pp.375-393
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• 2008

The purpose of this study is to investigate the Chinese investment environment and analyze the actual investment condition of Korean enterprises in China and examine the points at issue. In general, the investment environment in China shows satisfactory progress. China has a multiple and regional extension policy in investment. And the environment for investment changes to insufficiency of company profit, extension of service market, maintenance of legislative system, and insufficiency of preference about foreign company. There are situations of inclining to manufacturing, inclining of region, preference of independence investment, small-sized investment by small and medium enterprises, difficulty of financial assistance, excess of logistic cost, delay of logistic term, difficulty of settlement of legal dispute and difficulty of taking a relative information in investment of Korean enterprise in China. The results of the study indicate mostly that the investment of Korean enterprise into China needs turnover of service trade-tertiary industry, portfolio of investment territory, cooperation with Chinese enterprise through joint venture investment and a large-scale investment for extension of Chinese domestic market.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4025-4041
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• 2020

Mobile edge computing (MEC) is capable of providing services to smart devices nearby through radio access networks and thus improving service experience of users. In this paper, an offloading strategy for the joint optimization of computing and communication resources in multi-user and multi-MEC overlapping scene was proposed. In addition, under the condition that wireless transmission resources and MEC computing resources were limited and task completion delay was within the maximum tolerance time, the optimization problem of minimizing energy consumption of all users was created, which was then further divided into two subproblems, i.e. offloading strategy and resource allocation. These two subproblems were then solved by the game theory and Lagrangian function to obtain the optimal task offloading strategy and resource allocation plan, and the Nash equilibrium of user offloading strategy games and convex optimization of resource allocation were proved. The simulation results showed that the proposed algorithm could effectively reduce the energy consumption of users.

• Journal of Communications and Networks
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• v.11 no.4
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• pp.406-415
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• 2009

In this work, we consider performance modeling of a wireless sensor network with a time division multiple access (TDMA) media access protocol with slot reuse. It is assumed that all the nodes are peers of each other and they have two modes of operation, active and sleep modes. We model the sensor network as a Jackson network with unreliable nodes with on and off states. Active and sleep modes of sensor nodes are modeled with on and off states of unreliable nodes. We determine the joint distribution of the sensor node queue lengths in the network. From this result, we derive the probability distribution of the number of active nodes and blocking probability of node activation. Then, we present the mean packet delay, average sleep period of a node and the network throughput. We present numerical results as well as simulation results to verify the analysis. Finally, we discuss how the derived results may be used in the design of sensor networks.

• ETRI Journal
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• v.29 no.5
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• pp.596-606
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• 2007

It is well known that an OFDM receiver is vulnerable to synchronization errors. Despite fine estimations used in the initial acquisition, there are still residual synchronization errors. Though these errors are very small, they severely degrade the bit error rate (BER) performance. In this paper, we propose a residual error elimination scheme for the digital OFDM baseband receiver aiming to improve the overall BER performance. Three improvements on existing schemes are made: a pilot-aided recursive algorithm for joint estimation of the residual carrier frequency and sampling time offsets; a delay-based timing error correction technique, which smoothly adjusts the incoming data stream without resampling disturbance; and a decision-directed channel gain update algorithm based on recursive least-squares criterion, which offers faster convergence and smaller error than the least-mean-squares algorithms. Simulation results show that the proposed scheme works well in the multipath channel, and its performance is close to that of an OFDM system with perfect synchronization parameters.