• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.1
• /
• pp.110-115
• /
• 2000

A K-band GaAs MMIC receiver module has been developed using 0.15 ${\mu}{\textrm}{m}$ HEMT technology process. It incorporates two front end low noise amplifiers, a double balanced diode mixer, and filters. The RF input frequency ranges 20.1 to 21 GHz and the IF output 1.1 to 2 GHz. Test results show an overall conversion gain of more than 27 dB, and less than a 2.2 dB noise figure. The image-rejection ratio greater than 21 dB has been obtained. The isolation between RF and IF ports is better than 27 dB, and between LO and IF is more than 50 dB.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.4
• /
• pp.305-312
• /
• 2015

In this study, inter-turn short fault models of interior permanent magnet synchronous motors (IPMSM) are developed by adding saliency modeling to surface-mounted permanent magnet motor models. The saliency model is obtained using the deformed flux models based on both fault-winding flux information and inductance variations caused by cross-flux linkages that depend on the distribution of the same phase windings. By assuming the balanced three-phase current injection, we obtain the positive and negative sequence voltages and the fault current in the positive and the negative synchronous reference frames. The output torque model is developed by adding the magnet and the reluctance torque, which are derived from the developed models. To verify the proposed IPMSM model with an inter-turn short fault, finite element method-based simulation and experimental measurement results are presented.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2005.05a
• /
• pp.5-9
• /
• 2005

One of the imminent problems to be solved within wireless sensor network is to balance out energy dissipation among deployed sensor nodes. In this paper, we present a transmission relay method of communications between BS (Base Station) and CHs (Cluster Heads) for balancing the energy consumption and extending the average lifetime of sensor nodes by the fuzzy logic application. The proposed method is designed based on LEACH protocol. The area deployed by sensor nodes is divided into two groups based on distance from BS to the nodes. RCH (Relay Cluster Head) relays transmissions from CH to BS if the CH is in the area far away from BS in order to reduce the energy consumption. RCH decides whether to relay the transmissions based on the threshold distance value that is obtained as a output of fuzzy logic system. Our simulation result shows that the application of fuzzy logic Provides the better balancing of energy depletion and Prolonged lifetime of the nodes.

• Journal of Electrical Engineering and Technology
• /
• v.5 no.2
• /
• pp.290-298
• /
• 2010

This paper proposes an adaptive carrier-based pulse width modulation (PWM) method for a four-switch three-phase (4S3P) inverter under dc-link voltage ripple conditions. The proposed method guarantees balanced output currents despite of the existence of the voltage oscillations across two dc-link capacitors. And also, this new approach achieves a linear over-modulation with calculation time reduction. Simulation and experimental results are given to validate the feasibility of the proposed method.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.270-279
• /
• 2018

This paper elucidates a hysteresis current controller for enhancing the performance of static synchronous compensator (STATCOM) using cascaded H-bridge multilevel inverter. Due to the rising power demand and growing conventional generation costs a new alternative in renewable energy source is gaining popularity and recognition. A five level single phase cascaded multilevel inverter with two separated dc sources, which is energized by photovoltaic - wind hybrid energy source. The voltages across the each dc source is balanced and standardized by the proposed hysteresis current controller. The performance of STATCOM is analyzed by connecting with grid connected system, under the steady state & dynamic state. To reduce the Total Harmonic Distortion (THD) and to improve the output voltage, closed loop hysteresis current control is achieved using PLL and PI controller. The performance of the proposed system is scrutinized through various simulation results using matlab/simulink and hardware results are also verified with simulation results.

• Proceedings of the KIEE Conference
• /
• 2004.11b
• /
• pp.17-20
• /
• 2004

This paper presents a modeling and simulation of a grid-connected wind turbine generation system with respect to wind variations and three-phase fault in the system. It describes the modeling of the wind turbine system including the drive train model, induction generator model, and grid-interface model on MATLAB/Simulink. Case studies demonstrate that the pitch angle control is carried out to achieve maximum power extraction for wind speed variations and the duration of a fault on the system influences on the output of the wind turbine generator.

• 한국IT서비스학회:학술대회논문집
• /
• 2003.11a
• /
• pp.167-174
• /
• 2003

BPO(Business Process Outsourcing) is defined as outsourcing the management and operation of the IT intensive business process to another company that has specialty in managing the process. In the outsourcing arrangement, the design of the effective control mechanisms is essential to the success of the outsourcing. The purpose of this study is to investigate the effective control mechanisms between two organizations in a BPO arrangement. The specific research questions put forth are as follows: (1)What are the control issues in relation to BPO? (2)How the control mechanisms in the successful BPO arrangement are designed? and (3)What kind of effect or change do the designed control mechanisms have on the buyer's job process in terms of BPO? The results of this study found that the following mechanisms are effected in BPO setting: (1)Automation (2)Standardization & Modularity (3)Embedding (4)Balanced control (5)control segmentation (6)hierarchy (7)output/behavior control 8)back-end control 9)informal control.

• Journal of Korean Society for Quality Management
• /
• v.46 no.4
• /
• pp.863-876
• /
• 2018

Purpose: There are several KPI(key performance indicators) models: BSC(balanced scorecard), IPOO(Input-process-output-outcomes) indicators, QCDP(quality-cost-delivery-productivity) indicators. This paper analyze these models and gives some suggestions to help the effective usage of KPI. Methods: This paper reviews and summarize the criteria to evaluate the PI(performance indicators) through literature review. Evaluation and analysis on the PI factors of the KPI developing models is performed by the criteria. Results: Criteria to evaluate the PI, which can be used to evaluate the goodness of PI is suggested. This paper also proposes some suggestions for the KPI models and their factors for the effective development of PI in the organization. Conclusion: This research will help the managers to develop and select useful PI and KPI for their business and processes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.5 s.108
• /
• pp.483-489
• /
• 2006

In this paper, new wideband lens amplifiers are proposed for C-band wireless communication service. In order to obtain the wideband property, all components of the proposed lens amplifiers are designed with balanced structure and wideband characteristics. Fat dipole antenna as the input and output antenna, balanced amplifier as amplifying components, and coplanar stripline(CPS) as the delay line fer the beam focusing are used fur composing the stable wideband lens amplifier. The $5{\times}5$ 2D lens amplifier has the characteristics that the absolute gain is 7.5 dB, the EIPG is 37.4 dB at 6 GHz, and the 3-dB gain bandwidth is 19.8 %.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.05a
• /
• pp.787-790
• /
• 2003

A 4-wavelength optical transceiver system is designed and implemented by using 4 OADMs (optical add-drop multiplexers), WDMs, and optical transceivers. In this new system, the wavelengths of 1510 nm and 1530 nm are used for upload and download signals, respectively, as well as the wavelengths of 1550 nm and 1310 nm which have been utilized in a 2-wavelength optical transceiver systems. The 4-wavelength optical module shows very encouraging pass characteristics of about - 5 dB and isolation characteristics of less than -40 dB, which is configured with two OADMs, 4 couplers, and WDM couplers by fusion splicing. Noise figure (NF) of the one-stage balanced amplifier designed and fabricated for receiver module is 0.38 dB and the amplifying gain is 14.2 dB. S$_{11}$, S$_{22}$ and input, output VSWR are -28.81 dB, -32.08 dB, 1.05 : 1, 1.08 : 1, respectively.y.