• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.123-125
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• 2009

Mismatch of electrical characteristics of modules in PV string invokes mismatch power loss. The mismatch occurs due to various causes such as shadow, aging, contamination, and module exchange. The concept of mismatch compensation converter(MCC) is presented in this paper to remedy the mismatch loss problem. MCC is connected to irregular modules only. MCC is composed of dc-dc converter and MPPT controller. It is noted that MPPT algorithm is employed to control MCC and is effective for maximum power available from irregular modules. The selection guide of MPPT control period is given based on the period of MPPT in PCU. The effectiveness of the MCC is verified by a prototype experiment.

• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.441-444
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• 2007

The mechanical endurance is the critical characteristic of Magnetic contactors (MCs), which are widely used in such industrial equipments as elevators, cranes, and factory control rooms in order to close and open the control circuit. Testing time, however, is so long in most cases that some method of reducing the testing period is required. Therefore, the degradation test by the detected vibration of MCs is developed to reduce the testing time in this work. The degradation test data are analyzed and the prediction model is provided. Also, the possibility of this technology for Reliability Centered Maintenance (RCM) will be shown. This will reduce the period of the product development and raise the reliability of the equipment in power distribution.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.2
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• pp.26-30
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• 2000

In this paper, we obtain a mathematical model of a gas turbine control system from experimental data. The gas turbine in Gunsan power plant is selected as controlled system. The recursive least square algorithm is used to model the plant. For parameter estimation, plant is assumed as second order system and forgetting factor is 0.98 and the period of input and output signal period is 1sec. As a result, input and output characteristics of real system and modeling are identified.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.441-448
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• 2007

Heart rate variability (HRV) in electrocardiogram (ECG) is an important index for understanding the health status of heart and the autonomic nervous system. Most HRV analysis approaches are based on the proper heart rate (HR) data. Estimation of heart rate is thus a key process in the HRV study. In this paper, we report an innovative method to estimate the heart rate. This method is mainly based on the concept of periodicity transform (PT) and instantaneous period (IP) estimate. The method presented is accordingly called the "PT-IP method." It does not require ECG R-wave detection and thus possesses robust noise-immune capability. While the noise contamination, ECG time-varying morphology, and subjects' physiological variations make the R-wave detection a difficult task, this method can help us effectively estimate HR for medical research and clinical diagnosis. The results of estimating HR from empirical ECG data verify the efficacy and reliability of the proposed method.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.898-900
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• 2001

In general, the accuracy of the switching angles is dependent upon the resolution of the encoder and the sampling period of the microprocessor. But the region of high speed, switching angles are fluctuated back and forth from the preset values, which are cause by the sampling period of the microprocessor. Therefore, the low cost linear encoder suitable for the practical and stable SRM drive is proposed and the control algorithm to provide the switching signals using the simple analog type switching logic circuit is also presented in this paper.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.21-23
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• 2005

NARX(Nonlinear AutoRegressive with eXogenous input) neural network was used for prediction of nuclear reactor behavior which was influenced by control rods in short-term period and also by xenon and boron in long-term period in load following operations. The developed model was designed to predict reactor power, xenon worth and axial offset with different burnup rates when control rod and boron were adjusted in load following operations. Data of UCN 3 were collected by ONED94 code. The test results presented exhibit the capability of the NARX neural network model to capture the long term and short term dynamics of the reactor core and seems to be utilized as a handy tool for the use of a plant simulation.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.291-294
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• 2003

The Water resources utilization pattern of Jangsung reservoir was studied. The observed precipitation and existing reservoir operation data such as irrigation amount, reservoir storage, river maintenance requirement, flood control discharge were collected for ten years period and analyzed. Major findings of this study are as follows: The observed average, minimum, maximum annual precipitation were 905.1mm, 1,977.3mm, 1,554.3mm during study period, respectively. The average annual irrigation amount was 554.5mm, irrigation amount of drought years of '92 and '94 was 604.6mm, 679.2mm, respectively. However, irrigation amount of extended drought year '95 was 384.9mm. It showed that supplying capacity of Jangsung reservoir was limited when consecutive 2 year drought occurred. The main water resources usage of Jangsung reservoir was irrigation, but flood control discharge exceed irrigation amount exceptionally when high precipitation occurred. The reservoir operation record revealed that discharge for river maintenance was delivered even drought years.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.579-582
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• 1999

This paper presents a design method of deadbeat controller for DC motor driving a rotational system with gear. The results of sampling a continuous-data process does not guarantee that no ripples occur between the sampling instants in the continuous-data output, but the proposed deadbeat control system that consists of the integral controller and the full state observer, and zero order hold using in continuous systems, has many advantages of such as an output response without the ripple and reaching the steady state without error after a given sampling period and faster settling time than the optimal control system in the short sampling period. The results of case study through matlab simulation shown that the efficiency of the proposed controller for DC motor driving a rotational system with gear, is verified by comparing with optimal controller etc.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.441-446
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• 1998

As for safety assessment of a radioactive waste disposal facility, radiation dose to inadvertent intruders is evaluated according to scenarios related to intruder's postulated activities at the disposal site after the end of Institutional Control Period(ICP). Simple trench and Below Ground Vault(BGV) are considered for this study as alternative disposal systems, and different scenarios are applied to each disposal type. The results show that 300 years of ICP is needed for simple trench and 100 years for BGV. Even for BGV, concentration of long-lived radioactive nuclides should be limited considering degradation of BGV after 300 years.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.305-311
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• 2019

The objective of this study was to determine the safety test for propolis in Beagle based on blood count, serum biochemistry, and electrolyte. Total six beagle dogs were assigned to this experiment. To investigate the safety of propolis in beagle dogs, we performed oral administration of propolis (5%) for 8 weeks. Among six beagles, three beagle dogs were randomly allocated to the control group which were fed only regular fodder, and the other three dogs were assigned as the treatment group which were fed regular fodder and propolis (5%). No clinical signs were observed in neither group throughout the experimental period. During the experimental period, there were no significant change in feed intake, water consumption, and body condition. Also, there were no statistically significant differences in hematological and biochemical analyses between the control group and the treated group. Our safety study showed that oral consumption of propolis did not cause any toxicological effects in beagle dogs.