• Journal of Power Electronics
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• v.13 no.3
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• pp.400-408
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• 2013

This paper presents a discrete state-space controller using state feedback control and feed-forward decoupling to provide a desirable control bandwidth and control stability for dynamic voltage restorers (DVR). The paper initially discusses three typical applications of a DVR. The load-side capacitor DVR topology is preferred because of its better filtering capability. The proposed DVR controller offers almost full controllability because of the multi-feedback of state variables, including one-beat delay feedback. Feed-forward decoupling is usually employed to prevent disturbances of the load current and source voltage. Directly obtaining the feed-forward paths of the load current and source voltage in the discrete domain is a complicated process. Fortunately, the full feed-forward decoupling strategy can be easily applied to the discrete state-space controller by means of continuous transformation. Simulation and experimental results from a digital signal processor-based system are included to support theoretical analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.492-500
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• 2013

A balanced forward-flyback converter for high efficiency and high power factor using a foward and flyback converter topologies is proposed in this paper. The conventional AC/DC flyback converter can achieve a good power factor but it has the high offset current through the transformer magnetizing inductor, which results in a large core loss and low power conversion efficiency. And, the conventional forward converter can achieve the good power conversion efficiency with the aid of the low core loss but the input current dead zone near zero cross AC input voltage deteriorates the power factor. On the other hand, since the proposed converter can operate as the forward and flyback converters during switch turn-on and turn-off periods, respectively, it cannot only perform the power transfer during an entire switching period but also achieve the high power factor due to the flyback operation. Moreover, since the current balanced capacitor can minimize the offset current through the transformer magnetizing inductor regardless of the AC input voltage, the core loss and volume of the transformer can be minimized. Therefore, the proposed converter features a high efficiency and high power factor. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

• Journal of Korean Physical Therapy Science
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• v.19 no.3
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• pp.31-38
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• 2012

Background : The purpose of this study was to evaluate the effect of the kinesio taping on the forward head posture and to reduce secondary pain and attitude transformation by applying kinesio taping. Methods : The subjects were the C university students(n = 30) in Chung-buk district without medical history. They were divided into two groups:experimental group(N = 15) and control group(N = 15). Control group was heard verbal instructions to keep right attitude and Experimental group was applied to kinesio taping. Change of an attitude, such as an angle, distance, CROM, CVA, CRA prices, before and after experiment was measured respectively. Result : The results of this study showed that in comparison of pre and post changes, experimental group noticeable changes in angle, CROMSI and CVA(p<.05). Angle, CROMSI and CVA were significant differed between groups(p<.05). Conclusion : Kinesio taping application was seemed to be effective on the improvement of forward head position. Therefore, it is suggested that Kinesio taping application should be one the potential methods to facillitate the forward head position. Comprehensive research is required about a point of time and duration for intervention in clinical approach for subjects.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.140-149
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• 2017

This study proposes a new type of active-clamp forward-flyback converter with two transformers that operate in forward and flyback modes during on and off times, respectively, instead of not using an output inductor. The main switch can be turned on with zero-voltage switching (ZVS) using the leakage inductance of the transformer and the output capacitor of the main switch. The leakage inductance should be increased to ZVS. However, the ringing between the leakage inductance of the transformer and the parasitic output capacitance of the secondary side rectifier switches results in a serious voltage spike. A forward-flyback converter employing auxiliary inductor and auxiliary diode is proposed to overcome the problem. The operational principles are analyzed in detail and validated through experiments with a 385 V-to-53 V/37 A prototype.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.9-12
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• 2004

In this paper, a new small sized Lateral Trench Electrode Power MOS was proposed. This new structure, called LTEMOS(Lateral Trench Electrode Power MOS), was based on the conventional lateral power MOS. But the entire electrodes of LTEMOS were placed in trench oxide. The forward blocking voltage of the proposed LTEMOS was improved by 1.5 times with that of the conventional lateral power MOS. The forward blocking voltage of LTEMOS was about 240 V. At the same size, an improvement of the forward blocking voltage of about 1.5 times relative to the conventional MOS was observed by using ISE-TCAD which was used for analyzing device's electrical characteristics. Because all of the electrodes of the proposed device were formed in each trench oxide, the electric field was crowded to trench oxide and punch-through breakdown was occurred, lately.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.130-139
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• 2004

The Casing Oscillator is a bore file Equipment for the all-casing process. All-casing process is a method of foundation work in construction yard to oscillate steel Casing in the ground. The existing Casing Oscillator has some problem like not boring horizontally with disturbance and not driving Casing othor angle except horizon. To solve problem, the new structure Casing Oscillator is presented and studied. The performance of Casing Oscillator is improved by kinematics analysis. The Casing Oscillator is similar to the parallel manipulator in structure. So we obtain Inverse kinematics solution of Casing Oscillator easily. But it is difficult to solve forward kinematics of Casing Oscillator. T his paper presents a novel pose description corresponding to the structure characteristics of parallel manipulators. Through analysis on geometry theory, we obtain a new method of the closed-form solution to the forward kinematics using Kinematic Inversion. The closed-form solution contains two different meanings -analytical and real-time. So we reach the goal of practical application and control. Closed-form forward kinematics solution is verified by an inverse kinematics analysis. It shows that the method has a practical value for real -time control and inverse kinematics servo control.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.4
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• pp.1663-1668
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• 2018

This study was conducted to examine the effects of Evjenth-Hamberg stretching of the sternocleidomastoid, upper trapezius, and pectoralis major on the lung function of adults with forward neck posture. The subjects were 20 adult students in P university located in Pohang, Korea, whose degree of head forward displacement measured according to NEW YORK state posture test was mild. The subjects were randomly and equally assigned to the Evjenth-Hamberg Stretching group (EHSG, n=10) and the control group (CG, n=10). Their forced vital capacity (FVC), slow vital capacity (SVC), and maximal voluntary ventilation (MVV) were measured before and after the experiment. In within-group comparison, only the EHSG experienced statistically significant improvement in FVC, forced expiratory volume in the first second (FEV1), and peak expiratory flow (PEE) after the experiment, compared to before the experiment (.05

• Physical Therapy Korea
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• v.28 no.4
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• pp.273-279
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• 2021

Background: Lunge exercises are lower extremity rehabilitation and strengthening exercises for patients and athletes. Most studies have shown the effectiveness of the forward and backward lunge exercises for treating patellofemoral pain and anterior cruciate ligament injuries (by increasing lower extremity muscle activity) and improving kinematics. Objects: However, it is not known how the two different lunge movements affect trunk muscle activities in healthy individuals. The purpose of this study was to investigate the electromyographic activity of the rectus abdominis and erector spinae muscles during forward and backward lunge exercises in healthy participants. Methods: Twelve healthy participants were recruited. Electromyographic activity of the rectus abdominis and erector spinae was recorded using surface electrodes during forward and backward lunges, and subsequently normalized to the respective reference voluntary isometric contractions of each muscle. Results: Activity of the erector spinae was significantly higher than that of the rectus abdominis during all stages of the backward lunge (p < 0.05). The activity of the erector spinae was significantly greater during the backward than forward lunge at all stages (p < 0.05). Conclusion: Backward lunging is better able to enhance trunk motor control and activate the erector spinae muscles.

• Current Optics and Photonics
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• v.5 no.2
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• pp.173-179
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• 2021

The electroluminescence (EL) intensities of GaN-based light-emitting diodes (LEDs) are estimated based on their photoluminescence (PL) properties. The PL intensity obtained under open-circuit conditions is divided into two parts: the PL intensity under a forward bias lower than the optical turn-on voltage, and the difference between the PL intensities under open-circuit conditions and under forward bias. The luminescence induced by photoexcitation under a constant forward bias lower than the optical turn-on voltage is primarily the PL from the excited area of the LED. In contrast the intensity difference, obtained by subtracting the PL intensity under the forward bias from that under open-circuit conditions, contains the EL induced by the photocarriers generated during photoexcitation. In addition, a reverse photocurrent is generated during photoexcitation under constant forward bias across the LED, and can be correlated with the PL-intensity difference. The relationship between the photocurrent and PL-intensity difference matches well the relationship between the injection current and EL intensity of LEDs. The ratio between the photocurrent generated under a bias and the short-circuit current is related to the ratio between the PL-intensity difference and the PL intensity under open-circuit conditions. A relational expression consisting of the ratios, short-circuit current, and PL under open-circuit conditions is proposed to estimate the EL intensity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.2949-2963
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• 2019

A novel distributed compress-and-forward (CF) system based on multi-relay network is presented. In this system, as the direct link between the source and destination is invalid due to some reasons, such as the limited power, special working environment, or even economic factors, relays are employed to receive analog signals and carry on distributed compressed encoding. Subsequently, the digital signals are transmitted to the destination via wireless channel. Moreover, a theoretical analysis for the system is provided by utilizing the Chief Executive Officer (CEO) theory and Shannon channel capacity theory, and the rate-distortion function as well as the connection between the transmission rate and the channel capacity are constructed. In addition, an optimal signal-to-noise ratio (SNR) -based power allocation method is proposed to maximize the quantization SNR under the limited total power. Simulation result shows that the proposed CF system outperforms the amplify-and-forward (AF) system versus the SNR performance.