• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.1 no.1
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• pp.26-39
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• 2002

This paper describes design and implementation of home network control protocol for networked home appliances. The proposed network protocol has four-layered protocol structure and device-modem interface structure for the flexibility of modems based on power line communication. The standard message set is specified to guarantee the interoperability between various home appliances The proposed protocol can be easily implemented because it has minimum network overhead.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.71-72
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• 2017

본 논문에서는 비선형 최적화 기법을 이용하여 자기 포화(magnetic saturation) 및 교차 결합 현상(cross-coupling effect)을 고려한 매입형 영구자석 전동기(IPMSM)의 실시간 MTPA 제어 방법을 제안한다. 이는 토크 지령 추종과 최소 동손 운전을 만족하는 제한 최적화(constraint optimization) 문제로 접근할 수 있다. 이를 통해 유도한 연립 비선형 방정식의 경우, Levenberg-Marquardt 수치 해석법을 적용하여 안정적이면서 빠르게 해를 구할 수 있다. 이러한 방법을 이용하면 참조표(look-up table) 없이 운전 환경의 실시간 변동을 고려한 효율적인 MTPA 운전이 가능하다. 시뮬레이션을 통해 제안된 알고리즘의 전류 해가 최적 운전점과 일치함을 확인하였다.

• IEIE Transactions on Smart Processing and Computing
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• v.5 no.5
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• pp.346-348
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• 2016

Coordinated multi-point transmission is a candidate technique for next-generation cellular communications systems. We consider a system with multiple cells in which base stations coordinate with each other by sharing user channel state information, which mitigates inter-cell interference (ICI), especially for users located at the cell edge. We introduce a new user scheduling method that considers both ICI and intra-cell orthogonality. Due to the influence of ICI cancellation and the loss reduction of effective channel gain during the beamforming process, the proposed method improves the system sum rate, when compared to the conventional method, by an average of 0.55bps/Hz for different numbers of total users per cell.

• Journal of electromagnetic engineering and science
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• v.12 no.3
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• pp.210-215
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• 2012

This paper presents a compact microstrip triple-mode filter with enhanced skirt characteristics. The presented triple-mode filter configuration supports three transmission poles and three transmission zeros within the nearby passband. Two of transmission zeros are generated by a triple-mode resonator itself, and the third one is generated by small cross-couplings between the I/O ports. Each resonance condition and the transmission zero generation conditions are analyzed using an equivalent circuit. The bandpass filter is designed for a 2.4 GHz WLAN. The filter was fabricated with a relative dielectic constant of 3.5 and a thickness of 0.76 mm. The fabricated filter has a small size ($7.9mm{\times}7.2mm$, i.e., $0.107{\lambda}_g{\times}0.098{\lambda}_g$, where ${\lambda}_g$ is guided wavelength at a center frequency) and shows high performing skirt characteristics.

• Journal of Power Electronics
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• v.13 no.3
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• pp.437-446
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• 2013

This paper proposes a design scheme for an LCL-filter used for the three-parallel operation of the power converters in high-capacity wind turbines. The designs of the power devices and grid connected filter are difficult due to the high level voltages and currents in huge-capacity wind turbines. To solve these problem, this paper presents three-parallel operation and LCL-filter design techniques optimized by parallel operation. Furthermore, the design of an inverter side inductance of the LCL-filter is discussed in detail considering the switching modulation method. Simulation and experimental results demonstrate the validity of the designed filter and wind turbines.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.205-210
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• 2001

A new single stage power factor corrected AC/DC converter has been proposed, that is unified with buck topology and suitable for universal input. The design example of the proposed converter lot 5V 12A application has been presented. The design considerations and simulation results for the proposed converter have been shown. The simulation results show that the line input current harmonics can meet IEC 1000-3-2 Class D requirements for the line input voltage from 90 to 260V.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.11-12
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• 2016

기존 LCL 필터 설계 방법의 경우, 시뮬레이션에 기반한 반복 과정을 통해 필터 파라미터를 최적화므로 많은 시간이 소요된다. 하지만 본 논문에서는 3상 PWM 인버터와 LCL 필터 분석을 통해 설계 시 고려 사항을 단순화할 수 있다. 또한 LCL 필터의 다양한 제약 조건을 파악하고, 이러한 조건 하에서 제작 비용을 최소화할 수 있는 해석 해(analytical solution)를 도출한다. 결과적으로 제안된 단계적(step-by-step) 설계 방법을 통해 빠른 시간내에 최적화된 LCL 필터를 선정할 수 있다. 제안된 방법의 유효성은 시뮬레이션을 통해 최종 검증하였다.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.3
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• pp.113-122
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• 2004

In case of heat exchangers operating under frosting condition, the thermal resistance and the air-side pressure loss increase with a growth of frost layer. In this paper, a transient characteristic prediction model of the heat transfer for a multi-inverter heat pump with frosting on its surface was presented by taking into account the change of the fin efficiency due to the growth of the frost layer. This dynamic simulation program was developed for a basic air conditioning system composed of an evaporator, a condenser, a compressor, a linear electronic expansion valve, and a bypass circuit. The theoretical model was derived from measured heat transfer and mass transfer coefficients. We also considered that the heat transfer performance was only affected by the decrease of wind flow area. The calculated results were compared with the experimental results for frosting conditions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.12 s.354
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• pp.75-82
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• 2006

In this paper, we design the meander line inductors with high sensitivity and high quality factor(Q) using high characteristic impedance of aperture ground plate. Sensitivity as a frequency is new defined by variation of effective inductance per analysis frequency range instead of self resonance frequency (SRF). An equivalent lumped circuit is derived to explain the characteristic of high frequency inductor. The 4 nH meander line inductor with aperture ground plate has 0.45 nH/GHz of good sensitivity and 86 of Q at 0.7 GHz.

• Korean Journal of Food Science and Technology
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• v.41 no.4
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• pp.428-434
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• 2009

This study was conducted to evaluate the anti-hypertensive effect of Lactobacillus sp. isolated from Kimchi by examining its effects on renal angiotensin-converting enzyme (ACE) inhibitory activity, lipid components and blood pressure using the spontaneously hypertensive rat (SHR) system. Most Lactobacillus sp. extracts (lysozyme, sonication and ethyl acetate extracts) showed higher capacities for the inhibition of ACE activity than those of cultured media. Particularly, LG 7, 8 and 42 of Lactobacillus sp. showed the strongest inhibitory activity among the Lactobacillus sp. extracts. The concentrations of total cholesterol and triglycerides in the serum were lower in the Lactobacillus sp. administration groups than in the control group, but these differences were not significant. The HDL-cholesterol concentrations of the LG 42 administration groups (IX, X) were significantly higher than that of the control group. At 4 weeks, the systolic blood pressure (SBP) in the LG 42 Lactobacillus sp. ($1{\times}10^9$ cfu/mL) group (XI) was about 27% lower than that of the control group (V). No adverse effects were observed on the liver and there was no difference in the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) values among groups. The results of this study suggest that long term consumption of LG 42 Lactobacillus sp. may be beneficial to the prevention of high blood pressure.