• Journal of the Korean Society of Radiology
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• v.11 no.1
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• pp.19-25
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• 2017

In this study, in order to analyze the general awareness of the nuclear power according to the controversy of thyroid cancer around nuclear plant, we investigated risks, preference and economics regarding type of power, and awareness of pre-post nucl ear power targeting the Busan Metropolitan residents. As a result, there has been a change in people's awareness of nuclear power as a result of the controversy thyroid cancer around nuclear plant. Especially, there was the greatest increase in the risk factors compared to before the event(p<0.05). Negative awareness of nuclear risk was shown to be expressed differently accor ding to the difference between groups. It is thought that this is due to the different prior experience of each individuals or obtained information through the interaction with others rather than on scientific and objective grounds. In order to establish a nuclear power policy considering the level of the people in the future, it seems that the efforts to understand the attitudes and opinions of people about nuclear power and above all, a scientific trust in nuclear power should be guaranteed.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.416-418
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• 2008

Cost effective and high efficiency energy recovery circuit (ERC) using an address voltage source is proposed. Different from prior ERC, the proposed circuit uses a voltage source to charge a panel and a current source to discharge the panel. As a result, it can be achieved zero voltage switching (ZVS) of switches in H-bridge inverter and zero current switching (ZCS) of switches of the ERC. Moreover, the proposed ERC can obtain high efficiency, high performance and the decrease of the cost and the size.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.309-314
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• 1992

Many dynamic mechanical systems, such as parts-feeders, walking machines, and percussive power tools, are described by equations of motion which are discontinuous. The discontinuities result from kinematic constraint changes which are difficult to foresee, especially in presence of impact. A simulation algorithm for these types of systems must be able to algorithmically predict and detect the kinematic constraint changes without any prior knowledge of the system's motion. This paper presents a rule-based approach to the prediction and detection of kinematic constraint changes between bodies with arc and line boundaries. The developed algorithm's ability to accurately and automatically detect the unpredicted changes of kinematic constraints is demonstrated with a numerical example.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.301-307
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• 1995

A monitoring technique of spindle fairure should be investirated prior to researcs of fairure diagnosis. This work is about monitoring of unbalanced shaft and defected bearings. The major work is done via experiments and the vibration signal is analysed means of power spectrum technique, and root mean squqre, peak-to-peak. Relationship is quantitatively investigated between defects and these monitoring paramenters.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2097-2100
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• 1999

Nondestructive and destructive tests were performed the stator windings of three high voltage motors prior to the rewind. Nondestructive tests included ac current increase rate($\Delta$I), dissipation factor(${\Delta}tan{\delta}$), and maximum partial discharge(Qm) The destructive tests included breakdown at three phases with ac voltage. Flashover occurred between the connected winding of endwinding and the stator flame. In two cases creeping discharge occurred between the individual phase windings and the wedges In the stator ends. The results of destructive tests could rarely be determined the breakdown voltage.

• Journal of Preventive Medicine and Public Health
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• v.43 no.6
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• pp.543-548
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• 2010

Objectives: The objective of this study was to calculate sample size and power in an ongoing cohort, Korea radiation effect and epidemiology cohort (KREEC). Method: Sample size calculation was performed using PASS 2002 based on Cox regression and Poisson regression models. Person-year was calculated by using data from '1993-1997 Total cancer incidence by sex and age, Seoul' and Korean statistical informative service. Results: With the assumption of relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, sample size calculation was 405 events based on a Cox regression model. When the relative risk was assumed to be 1.5 then number of events was 170. Based on a Poisson regression model, relative risk=1.3, exposure:non-exposure=1:2 and power=0.8 rendered 385 events. Relative risk of 1.5 resulted in a total of 157 events. We calculated person-years (PY) with event numbers and cancer incidence rate in the nonexposure group. Based on a Cox regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, 136 245PY was needed to secure the power. In a Poisson regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, person-year needed was 129517PY. A total of 1939 cases were identified in KREEC until December 2007. Conclusions: A retrospective power calculation in an ongoing study might be biased by the data. Prospective power calculation should be carried out based on various assumptions prior to the study.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.835-842
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• 2014

Cutback control in a grid code is one of the functions of a wind power plant (WPP) that is required to support the system protection and frequency stability. When a cutback control command signal is delivered to the WPP from the system operator, the output of a WPP should be decreased to 20% of the rated power within 5 s. In this paper, we propose a dedicated cutback control algorithm of a WPP based on the ratio of the command power to the available power. If a cutback control signal is delivered, the algorithm determines the pitch angle for the cutback control and starts the pitch angle control. The proposed algorithm keeps the rotor speed at the speed before the start of the cutback control to quickly recover the previous output prior to the cutback control. The performance of the algorithm was validated for a 100 MW aggregated WPP based on a permanent magnet synchronous generator under various wind conditions using an EMTP-RV simulator. The results clearly shows that the proposed algorithm not only successfully reduces the output to the command power within 5 s by minimizing the fluctuation of the pitch angle, but also rapidly recovers to the output level before the cutback control.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.961-963
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• 2002

When high temperature superconducting(HTS) tapes are wound on former for HTS cable application, their critical characteristics are likely to be degraded seriously because of mechanical stress. In this study, prior to fabricate prototype HTS cables, we investigated the variation of critical characteristics of HTS tapes according to their pitch angles. For this work, we prepared the samples of HTS tapes on the former of which diameter is 3cm. Pitch angles of HTS tapes are $0^{\circ}$, $00^{\circ}$, $20^{\circ}$, $30^{\circ}$, $40^{\circ}$, respectively. We applied current up to 160 $A_{rms}$ to HTS tapes and investigated E-I characteristics. The critical current of HTS tapes was decreased as pitch angle increased. In addition, when the applied current was beyond their critical current, the rate of resistance increase of HTS tapes was in proportion to their critical current. Finally, We concluded that the pitch angles affected resistance increase of HTS tapes as well as critical current.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.298-299
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• 2018

In this study, the discriminant power of the DEA models which do not require the prior information of decision makers was evaluated. Entropy model, Bootstrap model, Benevolent Cross Efficiency model, Aggressive Cross Efficiency model and Game Cross Efficiency model were selected as the DEA model for discriminant power evaluation. The discriminant power of five DEA models was evaluated using coefficient of variation and degree of importance. According to the evaluation results, the rank of discrimination power was evaluated in the order of Entropy model, Aggressive CE model, Benevolent CE model, Game CE model, and Bootstrap model in both evaluation indexes.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.29-34
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• 2017

A CMOS-based temperature sensor is proposed for low-voltage and low-power on-chip thermal monitoring applications. The proposed temperature sensor converts a proportional to absolute temperature (PTAT) current to a PTAT frequency using an integrator and hysteresis comparator. In addition, it operates in the subthreshold region, allowing reduced power consumption. The proposed temperature sensor was fabricated in a standard 90 nm CMOS technology. Measurement results of the proposed temperature sensor show a temperature error of between -0.81 and $+0.94^{\circ}C$ in the temperature range of 0 to $70^{\circ}C$ after one-point calibration at $30^{\circ}C$, with a temperature coefficient of $218Hz/^{\circ}C$. Moreover, the measured energy of the proposed temperature sensor is 36 pJ per conversion, the lowest compared to prior works.