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감마선 조사가 조미오징어의 저장 중 품질특성에 미치는 영향
노정은,김병근,김현구,권중호 한국식생활문화학회 2004 韓國食生活文化學會誌 Vol.19 No.5
This study was conducted to investigate the changes in the quality of gamma-irradiated seasoned cuttle during storage. Seasoned cuttle packed in PVC film (0.06 mm) was stored at 15±1℃ for 6 months after treatment with doses of 0 to 7 kGy. Microbial populations of seasoned cuttle were 1.6×10^5 CFU/g in total aerobic bacteria, 10⁴~10^5 CFU/g in yeasts & molds, and negative in coliforms, which were effectively reduced by 3 kGy or higher up to the undetectable level(〈20 CFU/g). The pH and moisture content of the samples were not changed with irradiation, but moisture was some decreased during storage. The instrumental color (especially Hunter b value), pigments (lipophilic & hydrophilic) and TBA value of the samples increased with storage time as well as irradiation dose more than 3 kGy. The influence of storage condition, however, were more significant. Irradiation did not induce any changes in volatile basic nitrogen (VBN) and trimethylamine (TMA) contents, thereby maintaining their contents lower than those of the non-irradiated samples during storage by reducing the microbial load.
Ku, Hyun-Keun,Jung, Jun-Hyung,Park, Jin-Woo,Kim, Jang-Mok,Son, Yung-Dueg The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.3
This paper proposes a fault-tolerant control (FTC) strategy for an open-circuit fault (OCF) of a single IGBT in a two-parallel-connected three-phase AC-DC pulse-width-modulation (PWM) converter system. In the case of the parallel-connected PWM converter system, the OCF of the IGBT causes not only DC-link voltage fluctuation and grid current distortion, but also a zero-sequence circulating current (ZSCC). Although the effect of these problems can be reduced by existing FTC methods which is used in the single PWM converter, it is difficult to totally mitigate the problems due to the ZSCC. Therefore, this paper proposes a new FTC strategy to suppress the ZSCC using the healthy converter in the parallel-connected converter. First, it is analyzed how the difference in common-mode (CM) voltage between the two converters causes ZSCC flowing inside the parallel-connected converter under the fault condition. And then, the limitation of the existing control method for ZSCC is explained. To suppress the ZSCC using the healthy converter, the proposed control method uses a d-axis voltage injection of the healthy converter which does not affect an active power control. The effectiveness of the proposed FTC strategy is verified through experimental results.
Heat Transfer Characteristics of Liquid-Solid Suspension Flow in a Horizontal Pipe
Ku, Jae-Hyun,Cho, Hyun-Ho,Koo, Jeong-Hwan,Yoon, Suk-Goo,Lee, Jae-Keun The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.10
Particles in liquid-solid suspension flow might enhance or suppress the rate of heat transfer and turbulence depending on their size and concentration. The heat transfer characteristics of liquid-solid suspension in turbulent flow are not well understood due to the complexibility of interaction between solid particles and turbulence of the carrier fluid. In this study, the heat transfer coefficients of liquid-solid mixtures are investigated using a double pipe heat exchanger with suspension flows in the inner pipe. Experiments are carried out using spherical fly ash particles with mass median diameter ranging from 4 to $78{\mu}m$. The volume concentration of solids in the slurry ranged from 0 to 50% and Reynolds number ranged from 4,000 to 11,000. The heat transfer coefficient of liquid-solid suspension to water flow is found to increase with decreasing particle diameter. The heat transfer coefficient increases with particle volume concentration exhibiting the highest heat transfer enhancement at the 3% solid volume concentration and then gradually decreases. A correlation for heat transfer to liquid-solid flows in a horizontal pipe is presented.
Hyun-Keun Ku,Hye-Rim Seo,Jang-Mok Kim 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper presents the development of full simulation model for All Electric Ship (AES) based on medium voltage DC power system. AES is generally adopted Integrated Power Systems (IPS). AES has become popular both in commercial and military areas owing to the advantages of IPS. However, the configuration of IPS is complex and difficult to experimental verification. Therefore, a tool for effective analysis is highly required to have an insight into the ship electrical system. The proposed simulation model includes the mechanical and the electrical elements by using the MATLAB/Simulink tool. By using this model, proposed paper performs a comprehensive electrical analysis based on the different ship operating scenarios.
전기추진선박의 통합전력계통 시뮬레이션 모델에 관한 연구
구현근(Hyun-Keun Ku),곽기곤(Ki-Kon Kwak),김장목(Jang-Mok Kim) 전력전자학회 2015 전력전자학회 논문지 Vol.20 No.1
The simulation model of All-Electric-Ship consists of electrical and mechanical systems. Running the total simulation requires considerable time and causes a lack of computer memory, because the two systems have different dynamic characteristics. Therefore, integrated simulation is practically impossible. This paper proposes the simplified model of electrical system to reduce simulation time significantly, compared to the detailed model. The validity of the proposed simplified model is verified by comparing detailed and simplified simulation results. Thus, the simplified models are applied to the integrated system. As a result, total system simulation can be implemented.
배터리 충전을 위한 소형풍력 발전 시스템의 한계 풍속에 관한 연구
구현근(Hyun-Keun Ku),이형욱(Hyung-Uk Lee),김장목(Jang-Mok Kim) 대한전기학회 2014 전기학회논문지 Vol.63 No.4
Three phase PWM(Pulse Width Modulation) converter of the small-scale wind power system is able to charge battery under the rated wind speed regions. However, it is impossible to control output power of converter at the over win speed region because back-EMF(Electro Motive Force) of PMSG(Permanent Magnet Synchronous Generator) is higher than the battery terminal voltage of PMSG is reduced. However, the cut-off wind speed exists although battery charging algorithm is implemented by flux weakening control method. Therefore, this paper performs analysis of other factors which affects limitation wind speed. The validity of the analysis are verified through simulation.