• 전기학회논문지P
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• 제65권4호
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• pp.255-261
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• 2016

Korean Power System are operating a load shedding system to prevent voltage instability phenomenon caused by severe line contingencies. In order to apply the load shedding scheme should be selected a location, amount, delay time. Current load shedding system is load shedding amount that has been calculated in the steady-state analysis to load shed the total amount in first level, load shedding amount calculated in advance, it is possible to perform an unnecessary load shedding. In this paper, set a multi-level load shedding control strategy step-by-step selection of load shedding amount for the prevention of excessive load shedding. In addition, through a voltage resilience analysis of the power system by applying motor load ratio and sensitivity parameter to selection the multi level load shedding ratio and delay time. For this reason, to take advantage of the limit data of interchange power, by utilizing interface power flow data to set a multi-level load shedding control strategy for the stabilization of the Korean Power System.

• 가정과삶의질연구
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• 제31권5호
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• pp.201-210
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• 2013

The purpose of this study was to investigate the possibility of discriminating a high level of school adjustment in low-income school-aged children using interpersonal-related variables(mother attachment, peer attachment) and self-related variables(ego-resiliency, self-control). The subjects were 335 children in fourth, fifth and sixth grades in 4 elementary schools in Daegu. Mean(SD), t-test, and stepwise discriminant analysis were used for data analysis. Base on the results of the discriminant analysis, the discriminant functions suggested that the best predictor for distinguishing between a high level of school adjustment in low-income school-aged children and a low level of school adjustment was ego-resiliency. Self-control, mother attachment and peer attachment reliably separated the groups. And using ego-resiliency, self-control, mother attachment and peer attachment as predictors, the discriminant analysis correctly classified 92.3% of the participants.

• Journal of Ginseng Research
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• 제10권2호
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• pp.123-132
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• 1986

The pepsinogen secretion was stimulated by the cholecystokinin, caerulein, isoproterenol, and carbachol, respectively. But it was increased slightly and returned to control level by the combiantions of total saponin with each above the agents. Even though the atropine had the inhibition effect, the pepsinogen secretion was recovered to normal level from depressed condition by the combination of the atropine with total saponin. Propranolol showed the same pattern as atropine, too. On the other hand, the pepsinogen secretion was stimulated by the DBcAMP alone, but decreased to control level by the combination with the total saponin. In the case of DBcGMP, the pepsinogen secretion was decreased by itself, but stimulated the above control level by the combination with total saponin. Histamine alone had little effect on the pepsinogen secretion, but when combinated with total saponin, the pepsinogen secretion was increased. Serotonin alone and with total saponin, had no effect respectively, From the above results, the total saponin may have the normalization action stimulating or decreasing the pepsinogen secretion to the control level.

• 한국동물위생학회지
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• 제24권2호
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• pp.117-126
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• 2001

To ensure the safety of domestic livestock products, the government made it obligatory to enforce the hazard analysis critical control point(HACCP) in all domestic slaughterhouses. Under the HACCP, most of the hazards generated in slaughterhouses are bio-hazards, especially pathogenic bacteria. In order to reduce to the pathogenic bacteria, critical control point (CCP) is established and controled in the process of slaughter. A study was carried out to measure the level of bacterial contamination of swine carcass in 6 slaughterhouses selected. As a result, the aerobic plate counts(cfu/$\textrm{cm}^2$) of all samples was $10^2$-10 in average, except slaughterhouse C. The level of the aerobic plate counts on the surface of lower loin in slaughterhouse C was $10^4$ and it was considered that slaughterhouse C should set the process of manual transport of carcass as the CCP. Escherichia coli level was the highest in middle line cut surface. Especially, E coli level of slaughterhouses C and D were about 6.5- and 3.0-fold higher than that of other 4 slaughterhouses. Thus, it was considered that the slaughterhouses C and D should set the process of the entrails treatment as the CCP. The air contamination was measured at two point in a slaughterhouse. The air contamination level was 4-13 times higher than that of the standard Japanese slaughterhouses.

• Journal of Power Electronics
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• 제9권5호
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• pp.679-690
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• 2009

The paper presents a new photovoltaic inverter for stand-alone induction motor application. The proposed system is composed of two stages. First stage is for the photovoltaic dc power feeding and second stage is dedicated to the motor-inverter subsystem and control technique. A direct torque control (DTC) with a novel switching strategy for motor torque ripple minimization is introduced. The novel DTC strategy is based on selecting a suitable voltage vector group for motor torque ripple minimization. A three-level voltage source inverter (VSI) is used instead of a two level inverter because the first has more available vectors and lower ripples in the output current and flux than the second, thus it has lower torque ripples. The photovoltaic array and battery bank are sized and the configuration is indicated based on sun-hour methodology. Simulation results show a comparison between three systems; two level VSI with conventional DTC strategy, three level VSI with conventional DTC, and the proposed system that has a novel DTC switching strategy applied to three level VSI. The results show that the proposed system has lower ripples in the current, flux and torque of the motor.

• Child Health Nursing Research
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• 제11권3호
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• pp.301-307
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• 2005

Purpose: To investigate changes in mother's stress, degree of depression and level of milk secretion hormones when the mothers provided massage to their new born babies. Method: The study was conducted with 65 women who had delivered at a convalescence institute in Incheon between Sep 25, 2003 and Feb 10, 2004. The mothers were assigned to a control group or an experimental group. Infants of mothers in the experimental group received massage from their mothers twice a day for 10 days beginning on the 4th day after delivery. The data were processed using $x^2-test$, paired t-test and repeated measures ANOVA using the SAS program. Results: The level of cortisol, a stress hormone and depression were significantly different between the two groups (p=0.01 ;p=0.02). While fur plasma prolactin level, a milk secretion hormone, there was no significant difference(p=0.14). Conclusions: When massage was provided to new-born babies the cortisol level of the mothers decreased significantly compared to the control group which did not receive the massage. As the level of depression of the control group declined as time passed while the experiment group showed no difference and there was no difference in the plasma prolactin level, further study is suggested.

• 전력전자학회논문지
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• 제22권4호
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• pp.285-296
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• 2017

This paper proposes an improved modulation scheme for the medium voltage modular multi-level converter (MMC), which operates in the nearest level control and applies in the medium voltage direct current (MVDC) system. In the proposed modulation scheme, the offset (neutral-to-zero output) voltage is adjusted, with the phase voltage magnitude, thereby maintaining a constant value with N+1 level in the controllable modulation index (MI) range. In order to confirm the proposed scheme's validity, computer simulations for the 22.9 kV - 25 MVA MMC were performed with PSCAD/EMTDC, as well as hardware experiments for the 380 V - 10 kVA MMC. The proposed modulation scheme offers to build a constant pole voltage regardless of the MI value, and to build a phase voltage with improved total harmonic distortion (THD).

• Journal of Power Electronics
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• 제16권6호
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• pp.2162-2172
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• 2016

This paper presents a Direct Torque Control (DTC) strategy for the five-phase induction motor driven by a three-level five-phase inverter in order to improve the performance of the five-phase induction motor. In the proposed DTC technique, only 22 voltage vectors out of 243 available voltage vectors in a three-level five-phase inverter are selected and are divided in 10 sectors each with a width of $36^{\circ}$. The four different DTC combinations (DTC-I, II, III and IV) for a three-level five-phase induction motor drive are investigated for improving the performance of five-phase induction motor. All four of the DTC strategies utilize a combination of the same large and zero voltage vectors, but with different medium voltage vectors. Out of these four techniques, DTC-II gives the best performance when compared to the others. This DTC-II technique is analyzed in detail for improvements in the performance of five-phase induction motor in terms of torque ripple, x-y stator flux and Total Harmonics Distortion (THD) of the stator phase current when compared to its two-level counterparts. To verify the effectiveness of the proposed three-level five-phase DTC control strategy, a DSP based experimental system is build. Simulation and experimental results are provided in order to validate the proposed DTC technique.

• International Journal of Control, Automation, and Systems
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• 제2권2호
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• pp.220-227
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• 2004

This paper describes the design and implementation techniques of a generic Internet-based telerobotic system. The purpose is to make available the precious technical information and hands-on experience of the authors for the research community. The paper is based on the telerobotics system that the authors recently implemented between KAIST, Korea and Saga University, Japan. In its current functionality, two control modes: high-level supervisory control and low-level supervisory control are explored demonstrating their merits and demerits.

• 소음진동
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• 제6권2호
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• pp.215-224
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• 1996

Active vibration control is generally used to reduce vibration level by the actuators based on measured signal. Dynamic properties of a structure can be easily modified by the active vibration control, so that the vibration level may be effectively reduced to the magnitude below the allowable limit over a wide frequency rangs. In this paper, an instantaneous optimal control algorithm including acceleration feedback is presented for the active vibration control of large structures considering facts that the acceleration response can be easily measured, but the displacement and velocity response are obtained by numerically integrating the measured acceleration response with some errors. The adverse effect of the time delay is overcomed by taking into account the dynamic characteristics of an actuator and filters in the design of controller. Performance test is carried out using a hydraulic active mass driver on a test structure$(L{\times}W{\times}H;=;1200mm{\times}800mm{\times}1600mm, about;500kg)$ supported by four columns under base excitations. It is confirmed that the vibration level of the test structure are reduced to about 1/6 near resonance.