• Journal of Power Electronics
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• 제10권3호
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• pp.313-319
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• 2010

This paper proposes a new compensation algorithm for the current measurement errors in a DFIG (Doubly Fed Induction Generator). Generally, current measurement path with current sensors and analog devices has non-ideal factors like offset and scaling errors. As a result, the dq-axis currents of the synchronous reference frame have one and two times ripple components of the slip frequency. In this paper, the main concept of the proposed algorithm is implemented by integrating the 3-phase rotor currents into the stationary reference frame to compensate for the measured current ripples in a DFIG. The proposed algorithm has several beneficial features: easy implementation, less computation time, and robustness with regard to variations in the electrical parameters. The effectiveness of the proposed algorithm is verified by several experiments.

• ETRI Journal
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• 제29권4호
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• pp.421-429
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• 2007

This paper presents a direct-conversion CMOS transceiver for fully digital DS-UWB systems. The transceiver includes all of the radio building blocks, such as a T/R switch, a low noise amplifier, an I/Q demodulator, a low pass filter, a variable gain amplifier as a receiver, the same receiver blocks as a transmitter including a phase-locked loop (PLL), and a voltage controlled oscillator (VCO). A single-ended-to-differential converter is implemented in the down-conversion mixer and a differential-to-single-ended converter is implemented in the driver amplifier stage. The chip is fabricated on a 9.0 $mm^2$ die using standard 0.18 ${\mu}m$ CMOS technology and a 64-pin MicroLead Frame package. Experimental results show the total current consumption is 143 mA including the PLL and VCO. The chip has a 3.5 dB receiver gain flatness at the 660 MHz bandwidth. These results indicate that the architecture and circuits are adaptable to the implementation of a wideband, low-power, and high-speed wireless personal area network.

• 한국전산유체공학회지
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• 제17권1호
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• pp.44-53
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• 2012

Immersed boundary method(IBM) is a numerical scheme proposed to simulate flow field around complex objectives using simple Cartesian grid system. In the previous studies, the IBM has mostly been implemented to fractional step method based Navier-Stokes solvers. In this study, we implement the IBM to an incompressible Navier-Stokes solver which uses SIMPLE algorithm. The weight coefficients of the bi-linear and quadratic interpolation equations were formulated by using only geometric information of boundary to reconstruct velocities near IB. Flow around 2D circular cylinder at Re=40 and 100 was solved by using these formulations. It was found that the pressure buildup was not observed even when the bi-linear interpolation was adopted. The use of quadratic interpolation made the predicted aerodynamic forces in good agreement with those of previous studies. For an analysis of moving boundary, we smulated an oscillating circular cylinder with Re=100 and KC(Keulegan-Carpenter) number of 5. The predicted flow fields were compared with experimental data and they also showed good agreements.

• 대한기계학회논문집A
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• 제31권1호
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• pp.129-138
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• 2007

In this paper, a modified sensitivity control for the semi-active suspension system with a magneto-rheological (MR) damper is investigated. A 2-d.o.f quarter-car model together with a 6th order polynomial model for the MR damper is considered. For the purpose of suppressing the vertical acceleration of the sprung mass, the square of the vertical acceleration is defined as a cost function and a modified sensitivity control that updates the current input in the negative gradient of the cost function is proposed. The implementation of the proposed algorithm requires only the measurement of the relative displacement of the suspension deflection. The local stability of equilibria of the closed loop nonlinear system is proved by investigating the eigenvalues of the linearized ones. Through simulations, the passive suspension, the skyhook control, and the proposed modified sensitivity control are compared.

• 디지털산업정보학회논문지
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• 제9권2호
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• pp.99-109
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• 2013

In this paper, we propose a new system which captures real depth and color information from natural scene and implemented it. Based on it, we produced stereo and multiview images for 3-dimensional stereoscopic contents and introduced the production of a digital hologram which is considered to the next-generation image. The system consists of both a camera system for capturing images which correspond to RGB and depth images and softwares (SWs) for various image processings which consist of pre-processing such as rectification and calibration, 3D warping, and computer generated hologram (CGH). The camera system use a vertical rig with two paris of depth and RGB camera and a specially manufactured cold mirror which has the different transmittance according to wavelength for obtaining images with the same view point. The wavelength of our mirror is about 850nm. Each algorithm was implemented using C and C++ and the implemented system can be operated in real-time.

• 대한전자공학회논문지TC
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• 제41권12호
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• pp.77-84
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• 2004

ITS를 위한 차량 충돌 방지 시스템인 FMCW 방식의 자동차 레이더를 분석하고 이에 적합한 신호처리부를 설계하고 구현하였다. 77GHz 대역의 FMCW 레이더에 대하여 성능 파라미터를 거리와 속도 해상도가 각각 0.4m, 0.67Km/h이 되도록 설계하였으며, 다중 물체의 검출을 위한 다수의 비트주파수를 조합하는 방법에 대하여 검토했다. 또한 거리 주파수인 $f_r$과 속도 주파수 $f_d$의 범위를 다르게 설정하여 다중 물체의 처리가 훨씬 간단해지는 것을 보였다. 다중 물체들의 거리차로 인한 감쇄를 보정하도록 미분기를 전처리단에 사용하여 ADC 비트수를 8bit로도 충분히 검출할 수 있음을 보였다. 제안한 방법과 설계한 파라미터 값들을 사용하여 Matlab으로 모의실험으로 검증하고 DSP와 마이크로프로세서를 이용하여 구현하였다.

• 한국통신학회논문지
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• 제41권12호
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• pp.1700-1706
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• 2016

본 논문은 동시 전송 가능한 사물지능 통신 트래픽의 수를 늘리기 위하여 doubly truncated cyclic code shift keying (DTCCSK)을 활용한 대역 확산 알로하 기법을 제안한다. 제안하는 DTCCSK는 정사각형으로 표시되는 cyclic code shift keying 코드셋의 우측과 하단을 절삭함으로써 생성 가능하며, spreading factor와 심볼 길이를 자유롭게 설계할 수 있는 특징을 가진다. 또한 DTCCSK는 대역 확산 알로하의 변복조 기법으로 주로 사용되는 direct sequence 보다 높은 주파수 효율을 보이면서도 M-ary 시그널링 기법에 비해서는 낮은 구현 복잡도로 구현이 가능하다. 본 논문은 사물지능 통신을 위해 대역 확산 알로하를 채택한 S-band mobile interactive multimedia 표준을 참고하여 시뮬레이션 환경을 구성하였고 DTCCSK의 성능을 검증하였다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제2B권3호
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• pp.133-139
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• 2002

In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2016년도 추계학술발표대회
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• pp.514-517
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• 2016

동영상이나 게임에서 2차원적인 시야를 제공해주는 물건(컴퓨터,TV,스크린 등)이나 입체감을 주기위한 3D기술을 사용하여 보는 것에 만족하던 시대가 가고 VR(Virtual Reality)이 등장함으로 인해서 사람들이 점점 가상현실에 대한 환상을 가지고 있다. 본 연구에서는 많은 관심을 받는 VR과 동영상 Converter기술을 합쳐 공포 게임을 만들어 보며, 일반적인 공포 영상이 VR과 접목되면서 가져올 감정변화가 사람들의 관심을 끌 수 있음을 보이고자 한다.

• 보건행정학회지
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• 제15권4호
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• pp.1-25
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• 2005

Legislation on pharmaceutical reimbursement decision using economic evaluation results was made in Korea in fm, but has yet to be fully implemented. We evaluated the quality of Korean economic evaluation studies of pharmaceuticals to understand gaps between legislation and implementation. From this evaluation, we propose policy options that might strengthen the research Infrastructure In order to support such studies. We reviewed 23 published studies for drugs conducted between 1996 and 2004. Evaluation criteria included methodological characteristics, healthcare system characteristics, population characteristics, and applicability of results. Large variation in study quality was observed, particularly with study design, outcome data, treatment patterns and interpretation. Korean clinical data used was mostly from observational studies of 1-2 hospitals. Foreign data was extracted from clinical trials that did not Include Asian population and their selection criterion was not clarified. With respect to treatment patterns, medical records and hospital bills were used without adjustment regarding area, hospital type, and others. And next frequent situation relied on expert opinion from academic physicians in specialty practice. preference measures, when used, were not elicited from the Korean population. $78.3\%$ of studies did not clarify the funding source. If the Korean economic evaluation policy is to provide meaningful data for decision makers, the quality of cost-effectiveness studies will need to improve dramatically. This may involve access to or creation of better data, more diverse funding, unproved training of researchers and evaluators, and partnerships with technology manufacturers.