• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.461-470
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• 2014

This paper presents a probabilistic power flow (PPF) analysis method for distribution network incorporating the randomness and correlation of photovoltaic (PV) generation. Based on the multivariate kernel density estimation theory, the probabilistic model of PV generation is proposed without any assumption of theoretical parametric distribution, which can accurately capture not only the randomness but also the correlation of PV resources at adjacent locations. The PPF method is developed by combining the proposed PV model and Monte Carlo technique to evaluate the influence of the randomness and correlation of PV generation on the performance of distribution networks. The historical power output data of three neighboring PV generators in Oregon, USA, and 34-bus/69-bus radial distribution networks are used to demonstrate the correctness, effectiveness, and application of the proposed PV model and PPF method.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2147-2155
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• 2022

Nuclear safety-related underground liquid storage tanks, such as those used to store fuel for emergency diesel generators, are critical components for safety of hundreds of existing nuclear power plants (NPP) worldwide. Since most of those NPP will continue to operate for decades, a beyond design base (BDB) seismic screening of safety-related underground tanks in those NPP is beneficial and essential to public safety. The analytical methodology for buried tank subjected to seismic effect, including a BDB seismic evaluation, needs to consider both soil-structure and fluid-structure interaction effects. Comprehensive analysis of such a soil-structure-fluid system is costly and time consuming, often subjected to availability of state-of-art finite element tools. Simple, but practically and reasonably accurate techniques for seismic evaluation of underground liquid storage tanks have not been established. In this study, a mechanics based solution is proposed for the evaluation of a cylindrical underground liquid storage tank using hand calculation methods. For validation, a practical example of two underground diesel fuel tanks in an existing nuclear power plant is presented and application of the proposed method is confirmed by using published results of the computer-aided System for Analysis of Soil Structural Interaction (SASSI). The proposed approach provides an easy to use tool for BDB seismic assessment prior to making decision of applying more costly technique by owner of the nuclear facility.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.1
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• pp.27-32
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• 2022

Microbubble technology has been widely applied in various industrial fields. Recently, research on many types of microbubble application technology has been conducted experimentally, but there is a limit in deriving the optimal design and operating conditions. Therefore, if the computational fluid dynamics (CFD) analysis of multiphase flow is used to supplement these experimental studies, it is expected that the time and cost required for prototype production and evaluation tests will be minimized and optimal results will be derived. However, few studies have been conducted on multiphase flow CFD analysis to interpret fluid flow in microbubble generators using swirl flow. In this study, CFD simulation of multiphase flow was performed to analyze the air-water mixing process and fluid flow characteristics in a microbubble generator with a dual-chamber structure. Based on the simulation results, it was confirmed that a negative pressure was formed on the central axis of rotation due to the strong swirling flow. And it could be seen that the air inside the suction tube was introduced into the inner chamber of the microbubble generator. In addition, as the high-speed mixed fluid collided with external water sucked by the negative pressure near the outlet, a large amount of microbubbles was ejected due to the shear force between the two flows flowing in opposite directions.

• Journal of IKEEE
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• v.8 no.1 s.14
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• pp.152-159
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• 2004

In this study, we design the one-chip PWM IC with high voltage power switch (300V class LDMOSFET) for SMPS (Switching Mode Power Supply) application. Reference circuits generate constant voltage(5V) in the various of power supply and temperature condition. Error amp. is designed with large DC gain $({\simeq}65dB)$, unity frequency $({\simeq}190kHz)$ and large $PM(75^{\circ})$. comparator is designed with 2 stage. Saw tooth generators operate with 20kHz oscillation frequency. Also, we optimize drift concentration & drift length of n-LDMOSFET for design of high voltage switching device. It is shown that simulation results have the breakdown voltage of 350V. (using ISE-TCAD Simulation tool). PWM IC with power switching device is designed with 2um design rule and Bi-DMOS technology.

• Journal of Digital Contents Society
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• v.19 no.3
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• pp.435-443
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• 2018

Recently, with the explosive development of computing power, various methods such as RNN and CNN have been proposed under the name of Deep Learning, which solve many problems of Computer Vision have. The Generative Adversarial Network, released in 2014, showed that the problem of computer vision can be sufficiently solved in unsupervised learning, and the generation domain can also be studied using learned generators. GAN is being developed in various forms in combination with various models. Machine learning has difficulty in collecting data. If it is too large, it is difficult to refine the effective data set by removing the noise. If it is too small, the small difference becomes too big noise, and learning is not easy. In this paper, we apply a deep CNN model for extracting facial region in image frame to GAN model as a preprocessing filter, and propose a method to produce composite images of various facial expressions by stably learning with limited collection data of two persons.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.5
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• pp.465-475
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• 2012

This study was carried out with two goals. One was the development of a model of a wind turbine blade airfoil and the other was the application of this folding blade. In general, in large-sized (MW) wind turbines, damage is prevented because of the use of a pitch control system. On the other hand, pitch control is not performed in small wind turbines since equipment costs and maintenance costs are high, and therefore, the blade will cause serious damage. The wind turbine proposed in this study does not require maintenance, and the blades do not break during high winds because they are folded in accordance with changes in the wind speed. But generators are not cut-out, while maintaining a constant angle will continue to produce. The focus of this study, the wind turbine is continued by folding blade system in strong winds and gusts without stopping production.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.439-444
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• 2012

For the application of photo-detector as active layer, we have studied how to deposit SiGe thin film using an independent Si target and Ge target, respectively. Both targets were synthesized by purity of 99.999%. Plasma generators were generated by radio frequency (rf, 13.56 MHz) and direct current (dc) power. When Ge and Si targets were sputtered by dc and rf power, respectively, we could observe the growth of highly crystalline Ge thin film at the temperature of $400^{\circ}C$ from the result of raman spectroscopy and X-ray diffraction method. However, SiGe thin film did not deposit above method. Inversely, we changed target position like that Ge and Si targets were sputtered by rf and dc power, respectively. Although Ge crystalline growth without Si target sputtering deteriorated considerably, the growth of SiGe thin film was observed with increase of Si dc power. SiGe thin film was evaluated as microcrystalline phase which included (111) and (220) plane by X-ray diffraction method.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.4
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• pp.68-77
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• 1996

In this study, for the capacity estimation of emergency electric generators built in apartment complex using NEGA C 201 method, it was proposed application methods of simultaneously starting groups and demand factors. Also, it was suggested that capacities of the electric generator might be calculated for two kinds of electric facilities; one is loads for the convenience of tenants when main electric supply cuts off, and the other is loads for fire. For 7 apartment complex of large-size (about 1, 500 households), medium- size (about 1, 000 households) and small - size (about 500 households), electric generator capacities were calculated and electric power were measured. Through the comparison between calculated values and measured values, it could be proved the suitability of these application methods. In addition, the calculated electric generator capacities were appeared to fit into engin capacities by NEGA C 201 method as well as those by conventional method.

• Journal of Radiation Industry
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• v.18 no.1
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• pp.95-100
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• 2024

To establish a radioactive waste life cycle history management system, a series of processes including waste generation, classification, packaging, storage, transportation, and disposal were reflected in the information management system. A preliminary review process was introduced to reduce the amount of radioactive waste generated and manage it efficiently. Through this, the amount of radioactive waste generated must be checked from the beginning of the research, and the generated radioactive waste must be thoroughly managed from the stage of generation to final disposal. In particular, in the case of radioactive waste data generated during nuclear facility operation and each experiment, a radioactive waste information management system must be operated to receive information from the waste generator and integrate it with processing information at the management stage. The application process for small-package containers was reflected so that information such as the generation facility of radioactive waste, generation facility, project information, types of radioactive waste, major radionuclides, etc. In the radioactive waste management process, the preceding steps are to receive waste history from the waste generators. This includes an application for a specified container with a QR label, pre-inspection, and management request. Next, the succeeding steps consist of repackaging, treatment, characterization, and evaluating the suitability of disposal, for a process to transparently manage radioactive wastes.

• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.111-116
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• 2018

This study were carried out to evaluate the efficiency of using burn-type $CO_2$ generators in greenhouse for cultivation 'Seolhyang' strawberry ($Fragaria{\times}ananassa\;Duch.$) during winter season. The concentration of $CO_2$ was 200 to $600{\mu}mol{\cdot}mol^{-1}$ in the control, and 800 to $1,100{\mu}mol{\cdot}mol^{-1}$ in using burn-type $CO_2$ generator between 6 and 11 hours. At other times, it was observed that at similar concentration in the control and using burn-type $CO_2$ generator. Measured greenhouse air temperature inside the of using burn-type $CO_2$ generator was $2{\sim}3^{\circ}C$ higher than the control at 6 ~ 10 am. There was no temperature difference between treatments after 11 o'clock. Plant height, leaf length, leaf width, root diameter, fresh weight, and dry weight were not different between treatments. The marketable yield (kg/10a) of using burn-type generator were 4,131 kg, which was 519 kg higher than the control. Therefore, the total fruit yields increased 17% compared to the control.