• Journal of Power Electronics
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• v.10 no.5
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• pp.451-460
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• 2010

This paper presents a new kind of digital control metal halide lamp electronic ballast. A zero-voltage-switch quasi-square-wave (ZVS-QSW) dual Buck converter is adopted here. In this paper, a digital control method is proposed to achieve ZVS for the converter. This ZVS can be realized during the whole working condition. Single-cycle-peak-current control is proposed to solve the problem of excessive inductor current during a low-frequency reversal transient. Power loop control is also realized and its consistency for different lamps is good. An AVR special microcontroller for a HID ballast is used to raise the control performance, and the low-frequency square-wave control method is adopted to avoid acoustic resonance. A 70W prototype was built in the laboratory. Experimental results show that the electronic ballast works reliably. Furthermore, the efficiency of the ballast can be higher than 92%.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.7
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• pp.399-405
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• 2002

This paper presents an implementation of digital high-performance Position sensorless motion control system of an induction motor drives with Direct Torque Control(DTC). The system consist of closed loop stator flux and torque observer, speed and torque estimators, two hysteresis controller, optimal switching look-up table, IGBT voltage source inverter, and TMS320C31 DSP board. The stator flux observer is based on the combined current and voltage model with stator flux feedback adaptive control of which inputs are current and voltage sensed on motor terminal for wide speed range. The speed observer is using the model reference adaptive system(MRAS) with rotor flux linkages for speed turning signal. The simulation and experimental results are provided to evacuate the consistency and the performance of the suggested position sensorless control algorithm. The developed position sensorless system are shown a good motion control response characteristic and high performance features using 2.2[kw] general purposed induction motor.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.5
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• pp.1210-1218
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• 2007

Recently Atopic Dermatitis(AD) is increasing along with allergic disease. At present, there is no infallible cure for AD. Then AD patients undergo great suffering. This study is carried out to see whether or not the administering Danggwieumja(DG) along with Samhwangseje-gamibang(SG} as a medicine for external aplication, is effective in treating atopic dermatitis. To examine the effectiveness of the above prescription, the author made an observation of diverse immune responses. through the model of NC/Nga atopic mice. Results provided evidence that the DG administration along with SG can be used as a treatment means to atopic dermatitis. The results are as follows: The extent of Clinical skin severities in 13 and 16 week old NC/Nga mice treated with DG and SG, were reduced by 50.9%, 53.9% respectively, compared to the control NC/Nga mice with no drug treatment. IgE, IL-4, IL-5, IL-6, IgM and IgG1 levels in the serum of the NC/Nga mice treated with DG and SG were significantly decreased compared to those of the untreated control mice. In contrary, to the $IFN-{\gamma}$ level, significantly increased. The spleen weight of the NC/Nga mice treated with DG and SG significantly decreased compared to those of the untreated control mice. CCR3 gene expression in the skin tissue of NC/Nga mice treated with DG and SG were highly decreased, and the IL-6 expression significantly decreased, and the $IFN-{\gamma}$ gene expression increased compared to those of the untreated control mice. Histological observation of the ear and dorsal skin tissue of the NC/Nga mice treated with DG and SG, showed that the extents of inflammation and infiltrated immune cells in the epidermal tissue and dermis, were highly reduced compared to those of the untreated control mice. In the model inducing COX-2 activity in RAW 264.7 cell, the denser DG became, the more COX-2 activity was inhibited, compared to those of the untreated control group. $IL-1{\beta}$, and $TNF-{\alpha}$, IL-6 gene expression in RAW 264.7 cell with DG, significantly decreased, compared to those of the untreated control group. According to the assessment of cell toxicity in L929 cell, the rate of cell multiplication increased by 3% in consistency to 100ppm of DG compared to the untreated control group and in more than the 200 ppm consistency, cell toxicity was occurred.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.171-172
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• 2011

The paper proposes a close loop control algorithm for Z-source inverter. The algorithm is realized by PWM duty ratio control in order to improve the output voltage to it's desired level. The controller consist of the output voltage PID controller and DC input voltage P controller. Using the DQ coordinate transformation simplify the controller design. The PSIM simulation results verify the validity by means of comparing the system with or without compensation and estimating if the system has output consistency function when ZSI's load and input voltage value changing.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.317-320
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• 1999

A robust end time optimal conかof strategy for dual-stage servo system is presented. The time optimal trajectory for a mass-damper system is determined and given os a reference input to the servo system. The feedback controller is constructed so that the fine stage tracks the coarse stage errors and robustly designed as the“perturbation compensated sliding mode control(PCSMC)”law, a combination of slid-ing mode controller(SMC) and perturbation observer(PO). In addition, a null motion controller which regulates the fine stage at its neutral position is designed based on the“dynamic consistency”So, the overall dual-stage servo system exhibits the robust and time-optimal performance. The inherent merit and performance of the dual-stage system will be shown.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.16-18
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• 2001

Despite extensive research on R-trees, most of the proposed schemes have not been integrated into existing DBMS due to the lack of protocol to provide consistency in concurrent environment. R-link tree is an acceptable data structure to deal with this issue., but still not enough. In this paper, we focus on a simplified predicate locking mechanism based on R-link tree for concurrency control and phantom protection. An in-memory operation control list (OCList) used to suspend some conflicting operations is designed here. The main features of this approach are (1) it can be implemented easily and do not need any extra information. (2) Only-one-lock is held when descending R-tree even when node split happens, while lock-coupling scheme is performed when ascending. No deadlocks are possible. (3) Searches and insertions are not unnecessarily restricted. (4) Insert and Delete phantom in R-link tree are avoid through beforehand predication.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2646-2653
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• 1993

A rotational torque calibration system is developed to measure rotational torque of power generating systems and to calibrate non-contact rotational torque measurement systems. The maximum capacity of the developed system is 4.5 N-m. It is composed of a DC motor, a DC generator, a control system, a master torque cell, a slip ling/brush set, supporters, a bed etc. The control system is characterized by the closed-loop control with differential intergrator. Rotational torque measurement test and unit response test are conducted to estimate the accuracy of the developed system. It is found that system maintain high consistency and accuracy with the maximum error of 0.25%, Therefore the developed system can be used to measure the rotational torque of power generating systems and to calibrate non-contact rotational torque measurement systems.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.4
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• pp.136-144
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• 1983

In this paper, a new scheme of implicit MRAC is presented for single input single output discrete system. The MRAC can be applied to the nonminimum phase system, too. They have simple structure because the parameters of the controller are estimated directly by changing the plant output equation properly. In this scheme, the observation process is well seperated from the adaptation process, so the adaptation algorithm is derived from the exponentially weighted least square method which has fast convergence characteristics and can deal with the time varying plant. The consistency of the estimated parameter is proved. And it is also proved the whole system has the stabilizing property. The effectiveness of the algorithm and the structure is illustrated by the computer simulation of the model reference adaptive control for a third order plant. It is proposed how to select the selectable parameters in the adaptive control system from the simulation results.

• Journal of the Korean Mathematical Society
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• v.39 no.5
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• pp.745-764
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• 2002

In this paper we Study a time-optimal model of pursuit in which the players move on a plane with bounded velocities. This game is supposed to be a nonzero-sum group pursuit game. The main point of the work is to construct and compare cooperative and non-cooperative solutions in the game and make a conclusion about cooperation possibility in differential pursuit games. We consider all possible cooperations of the players in the game. For that purpose for every game $\Gamma(x_0,y_0,z_0)$ we construct the corresponding game in characteristic function form $\Gamma_v(x_0,y_0,z_0)$. We show that in this game there exists the nonempty core for any initial positions of the players. The core can take four various forms depending on initial positions of the players. We study how the core changes when the game is proceeding. For the original agreement (an imputation from the original core) to remain in force at each current instant t it is necessary for the core to be time-consistent. Nonemptiness of the core in any current subgame constructing along a cooperative trajectory and its time-consistency are shown. Finally, we discuss advantages and disadvantages of choosing this or that imputation from the core.

• The Journal of Information Systems
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• v.20 no.2
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• pp.81-107
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• 2011

Group features such as group cohesion and consistency on appropriation(COA), which have been constructed through social interactions, should be noted for characterizing online game, especially, clan based massively multi-players online game (MMOG). This study attempted to identify the relationship between group characteristics and users' effectiveness of MMOG considering group experience. For this purpose, a research model was suggested: group cohesion and COA are variables for explaining group features, perceived use control is a variable for individual competency of playing MMOG, and perceived winning and perceived enjoyment are dependent variables. Moreover, group experience was included as a moderating variables for two relationships, group cohesion-preceived winning and COA-perceived winning. For the validation of this research model, 100 users for Sudden Attack which is one of very well known MMOG games were surveyed by questionnaires. Before survey, they were grouped into 10 teams and were played over ten times by team for perceiving group consciousness. In result, most hypotheses were statistically supported except the relationship between group cohesion and perceived winning.