• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.9-10
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• 2010

The lighting control power circuits should be designed in stable region according to the environment. A stable circuit is analyzed using ac equivalent circuits. The flyback converter with wide input voltage ranges is suitable for lighting control system. It is designed optimally for stability. The specifications are that the input voltage is 90V-230V, the output power is 12V/2.5A. The stability analysis is established using PSM(Phase Sensitive Multimeter) in experiment. As a result, it is confirmed that the gain margin and the phase margin are in stable area. The validity of the experimental measurement is verified.

• Structural Engineering and Mechanics
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• v.37 no.3
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• pp.257-265
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• 2011

Plant-specific analyses of 5 types of domestic reactors in Korea are performed to assure the structural integrity of the reactor pressure vessel (RPV) during transients which are expected to initiate pressurized thermal shock (PTS) events. The failure probability of the RPV due to PTS is obtained by performing probabilistic fracture mechanics analysis. The through-wall cracking frequency is calculated and compared to the acceptance criterion. Considering the fluence at the end of life expected by surveillance test, the sufficient safety margin is expected for the structural integrity of all reactor pressure vessels except for the oldest one during the pressurized thermal shock events. If the flaw with aspect ratio of 1/12 is considered to eliminate the conservatism, the acceptance criteria is not exceeded for all plants until the fluence level of $8{\times}10^{19}\;n/cm^2$, generating sufficient margin beyond the design life.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1555-1557
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• 2002

We have investigated the precharge type sense amplifier, it is suitable fur voltage sensing in a NOR type single transistor ferroelectric field effect transistor (1T FeFET) memory read operation. The proposed precharge type sense amplifier senses the bit line voltage of 1T FeFET memory. Therefore, the reference celt is not necessary compared to current sensing in 1T FeFET memory, The high noise margin is wider than the low noise margin in the first inverter because requires tile output of precharge type sense amplifier high sensitivity to transition of input signal. The precharge type sense amplifier has very simple structure and can sense the bit line signal of the 1T FeFET memory cell at low voltage.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.255-256
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• 2007

본 논문에서는 주파수 응달특성의 해석을 통하여 제어기를 설계하는 방법을 제안하였다. 모델의 오차가 없다는 가정 하에 완벽 제어가 가능한 IMC-PID 구조를 사용 한으로 하나의 변수인 제어 조절 인자만으로 제어기를 설계하였다. 이 변수를 선정하는 방법으로는 위상여유와 이득여유를 고려한 방법을 수학적으로 유도하였다. 이는 설계자가 이미 알고 있는 일반적인 유도 식을 이용함으로 설계를 보다 쉽게 할 수 있다. 이를 통하여 원하는 설계사양을 만족 시키도록 하는 IMC-PID제어기의 설계 변수 값들을 수학적으로 제시하고, 그 유용성을 사례 연구와 분석을 통해 검토하였다.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.78-85
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• 2007

In this study, we performed finite element analysis for the design of a medical centrifuge and two-types of centrifuge were compared with each other. The types of centrifuge are 2-arm straight type and 3-arm type. Structural analysis was done with respect to the change of the rotational speed of the rotor of a centrifuge. When the rotor of centrifuge was rotated, the von Mises stress of 2-arm straight type-rotor was compared with the von Mises stress of 3-arm type. The margin of safety was estimated from the result. We found the critical speed of centrifuge from the campbell diagram by modal analysis.

• Journal of Technologic Dentistry
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• v.42 no.1
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• pp.45-53
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• 2020

Purpose: The purpose of this study was to investigate the current status and satisfaction of dental CAD/CAM system. Methods: A survey of dental technicians was conducted and a total of 353 responses were used for analysis. The satisfaction difference according to career was analyzed by ANOVA and tukey HSD (α = .05). Results: Satisfaction with the design program was 3.64 ± .86, the highest among all items. On the other hand, the satisfaction with price was 2.75 ± 1.02, which was the lowest. The difference according to career was statistically significant in the following items. Frequent breakdown, single crown margin, bridge crown margin, retentivity, price, A/S, equipment training (p<.05). Conclusion: As the materials applied to dental CAD/CAM are expanding and the types of prostheses are diversified, the use rate of CAD/CAM is continuously increasing. The dental CAD/CAM system will need to be improved in a way that will satisfy all patients, dentists and dental technicians.

• Asia-Pacific Journal of Business
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• v.13 no.1
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• pp.185-195
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• 2022

Purpose - This study attempts to analyze the determinants of inventory turnover by applying quantile regression analysis. Design/methodology/approach - By selecting the gross margin, capital intensity, and sale surprise as the determinants of inventory turnover, we investigate their effects on inventory turnover at the several quartiles (10%, 25%, 50%, 75%, 90%) of inventory turnover with quantile regression analysis. Findings - The effects of gross margin and capital intensity on inventory turnover are different for each quartile. But the effects of sale surprise on inventory turnover are not different for each quartile. Research implications or Originality -This study is the first attempt to examine the effects of inventory turnover determinants on inventory turnover by applying quantile regression analysis was not employed in the prior studies. Thus, this study is meaningful in that it shows the possible way to review inventory management strategies that can be applied differently to the firms with different inventory turnover levels.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.508-513
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• 1997

One of the moot important constants to be Installed In COLSS, a monitoring system in CE typed reactors, is ROPM which would limit the operating space. This static ROPM was calculated from digital transient analysis assuming that every design basis transient was initiated from the most severe initial condition combination (LCO). Once It could be assured that core condition would not be located at none other than LCO, this static ROPM could be replaced with dynamic ROPM calculated at that condition and the dynamic ROPM would be definitely less than the static ROPM. In order to do, It must be required to calculate the transient discrete sensitivity parameters and parameters change distribution. The purpose of this report is just to propose the enlargement method for thermal margin.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.295-298
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• 1997

In large system, design margin makes relatively price higher. So, optimal design through exact analysis of thermal behavior is needed. In this paper, we propose the equivalent load test facility using two inverter & converter system and inductors. Applying actual electrical profiles for motor drive, thermal characteristics of power converter fed AC motor drive are obtained, and the results are compared with simulation results.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.145-151
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• 2004

In this paper, a pressure control type ratio control valve(RCV) is designed for a metal belt CVT. Steady state and transient characteristics of the pressure control CVT are investigated by simulations and experiments. In addition, P-line is proposed to predict the shift performance. It is found that the bigger the pressure margin, the faster the shift response. It is expected that the P-line can be used in design of the RCV to meet the desired shift performance.