• 조명전기설비학회논문지
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• 제20권3호
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• pp.12-19
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• 2006

마이크로소스는 1[kW]${\sim}$수[MW] 사이의 전력을 공급하고, 기존의 대규모 발전설비보다 높은 신뢰도와 에너지 효율을 가지는 고품질의 전력을 공급할 수 있다. 본 논문에서는 마이크로소스의 스위칭레벨 모델을 개발하였으며, 다수의 마이크로소스가 전력시스템과 연계되어 마이크로그리드를 형성할 경우의 특성에 대하여 연구하였다. 마이크로소스는 인버터의 효율을 극대화 할 수 있도록 공간벡터 펄스폭변조(Space Vector PWM, SVPWM) 기법을 채용하였으며, 마이크로소스의 제어시스템 파라미터 특성 및 마이크로소스 상호작용에 관하여 연구하였다. 마이크로소스는 PSCAD/EMTDC를 이용하여 구현하였으며 이를 이용해 마이크로그리드를 구성하여 시뮬레이션하였다. 사례 연구를 통하여 제안된 모델의 효용성을 확인하였다.

• 제어로봇시스템학회논문지
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• 제19권8호
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• pp.718-724
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• 2013

In today's automotive industry, there exist several systems that help drivers reduce the possibility of accidents, such as the ADAS (Advanced Driver Assistance System). The ADAS helps drivers make correct and quick decisions during dangerous situations. This study analyzed the performance of the IMM (Interacting Multiple Model) method based on multiple Kalman filters using the data acquired from a driving simulator. An IMM algorithm is developed to identify the current discrete state of neighboring vehicles using the sensor data and the vehicle dynamics. In particular, the driving modes of the neighboring vehicles are classified by the cruising and maneuvering modes, and the transition between the states is modeled using a Markovian switching coefficient. The performance of the IMM algorithm is analyzed through realistic simulations where a target vehicle executes sudden lane change or acceleration maneuver.

• 한국정밀공학회지
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• 제18권4호
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• pp.209-218
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• 2001

Ultrasonic motors are newly developed motors which are expected to be useful as actuators in many practical systems such as robot arms or manipulators because of several advantages against the electromagnetic motors. However, the precise control of the ultrasonic motor is generally difficult due to the absence of appropriate and rigorous mathematical model. Furthermore, owing to heavy nonlinearity, the position control of a pendulum system driven by the ultrasonic motor has a problem that control method using multiple neural network controllers based on a fuzzy inference system that can determine the initial position of the pendulum in the beginning of control operation. In addition, and appropriate neural network controller that has been learned to operate well at the corresponding initial position is adopted by switching schemes. The effectiveness of the proposed method was verified and evaluated from real experiments.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권4호
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• pp.255-261
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• 2005

With the advent of sub-90nm technologies, the system-on-chip (SoC) and system-in-package (SiP) are becoming the trend in delivering low-cost, low-power, and small-form-factor consumer electronic systems running at multiple GHz. The shortened transistor channel length reduces the transistor switching cycles to the range of several picoseconds, yet the time-of-flights of the critical on-chip and off-chip interconnects are in the range of 10 picoseconds for 1.5mm-long wires and 100 picoseconds for 15mm-long wires. Designers realize the bottleneck today often lies at chip-to-chip interconnects and the industry needs a good model to compute the inductance in these parts of circuits. In this paper we propose a new method for extracting accurate equivalent inductance circuit models for SPICE-level circuit simulations of system-on-chip (SoC) and system-in-package (SiP) designs. In our method, geometrical meshes are created and numerical methods are used to find the solutions for the electromagnetic fields over the fine meshes. In this way, multiple-GHz SoC and SiP designers can use accurate inductance modeling and interconnect optimization to achieve high yields.

• ETRI Journal
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• 제24권1호
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• pp.43-55
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• 2002

This paper proposes a flow-based admission control algorithm through an Asynchronous Transfer Mode (ATM) based Multi-Protocol Label Switching (MPLS) network for multiple service class environments of Integrated Service (IntServ) and Differentiated Service (DiffServ). We propose the Integrated Packet Scheduler to accommodate IntServ and Best Effort traffic through the DiffServ-aware MPLS core network. The numerical results of the proposed algorithm achieve reliable delay-bounded Quality of Service (QoS) performance and reduce the blocking probability of high priority service in the DiffServ model. We show the performance behaviors of IntServ traffic negotiated by end users when their packets are delivered through the DiffServ-aware MPLS core network. We also show that ATM shortcut connections are well tuned with guaranteed QoS service. We validate the proposed method by numerical analysis of its performance in such areas as throughput, end-to-end delay and path utilization.

• Journal of information and communication convergence engineering
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• 제13권3호
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• pp.189-196
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• 2015

In this paper, we present a rotating auto-zeroing offset cancellation technique, which can improve the performance of touch screen sensing circuits. Our target touch screen detection method employs multiple continuous sine waves to achieve a high speed for large touch screens. While conventional auto-zeroing schemes cannot handle such continuous signals properly, the proposed scheme does not suffer from switching noise and provides effective offset cancellation for continuous signals. Experimental results show that the proposed technique improves the signal-to-noise ratio by 14 dB compared to a conventional offset cancellation scheme. For the realistic simulation results, we used Cadence SPECTRE with an accurate TSP model and noise source. We also applied an asymmetric device size (10% MOS size mismatch) to the OP Amp design in order to measure the effectiveness of offset cancellation. We implemented the proposed circuit as part of a touch screen controller system-on-chip by using a Magnachip/SK Hynix 0.18-µm complementary metal-oxide semiconductor (CMOS) process.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 제15회 음성통신 및 신호처리 워크샵(KSCSP 98 15권1호)
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• pp.225-230
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• 1998

In this paper, a Kalman filter approach for enhancing speech signals degraded by statistically independent additive nonstationary noise is developed. The autoregressive hidden markov model is used for modeling the statistical characteristics of both the clean speech signal and the nonstationary noise process. In this case, the speech enhancement comprises a weighted sum of conditional mean estimators for the composite states of the models for the speech and noise, where the weights equal to the posterior probabilities of the composite states, given the noisy speech. The conditional mean estimators use a smoothing spproach based on two Kalmean filters with Markovian switching coefficients, where one of the filters propagates in the forward-time direction with one frame. The proposed method is tested against the noisy speech signals degraded by Gaussian colored noise or nonstationary noise at various input signal-to-noise ratios. An app개ximate improvement of 4.7-5.2 dB is SNR is achieved at input SNR 10 and 15 dB. Also, in a comparison of conventional and the proposed methods, an improvement of the about 0.3 dB in SNR is obtained with our proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.182-187
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• 1998

In this paper, the dynamic analysis and design of an AC to AC power supply with DC current link is presented. Despite many advantages of such a structure, its application in fixed frequency power supplies has received very little attention in the literature. Different issues related to dynamic analysis of the proposed system are considered. These include a simple averaging technique for modeling switching function generators, the concept of Internal Model Controllers, and necessary condition to avoid multiple crossing in ramp comparison methods. Theoretical and experimental results obtained from a DSP-based laboratory type setup are presented.

• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.68-74
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• 2002

In this paper, a pre-layout design approach for high-speed microprocessor is proposed. For multilayer PCB stark up configuration as well as selection and placement of decoupling capacitors, an effective solution for reducing SSN and EMI is obtained by modeling and simulation of complete power distribution system. The system model includes VRM, decoupling capacitors, multiple power and ground planes for core voltage, vias, as well as microprocessor. Finally, the simulation results are verified by measurements data.

• 한국항만경제학회지
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• 제37권4호
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• pp.89-102
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• 2021

본 연구는 항만물류서비스산업의 한 분야인 우리나라 예선서비스산업을 대상으로 해운대리점을 포함한 해운서비스기업의 지각된 관계 혜택과 전환장벽, 그리고 고객충성도 간의 관계를 규명하고자 수행되었다. 연구가설검정을 위해 예인서비스 구매자인 선사, 대리점 등 해운서비스기업의 종사자를 대상으로 설문조사를 실시하였다. 수집된 자료를 바탕으로 SPSSWIN ver. 18.0을 이용하여 Cronbach's α 계수를 이용한 측정변수의 신뢰성검정, 요인분석을 이용한 타당성검정, 가설검정을 위한 다중회귀분석 등을 실시하였다. 본 연구의 결과를 요약하면 다음과 같다. 먼저 예선서비스 구매자인 해운서비스기업이 지각하는 관계혜택은 사회적 혜택, 경제적 혜택, 확신적 혜택, 고객화 혜택 등 4개의 요인으로 구성되어 있음을 확인할 수 있었다. 둘째, 지각된 해운서비스기업의 관계 혜택은 전환장벽에 정(+)의 영향을 미칠 것이라는 가설 1은 채택되었다. 이러한 분석결과는 해운서비스기업과 예인서비스기업의 유대관계가 친밀할수록 거래업체를 변경하는데 소요되는 전환장벽이 증가하게 된다는 것을 의미한다. 셋째, 해운서비스기업의 전환장벽은 고객충성도에 유의한 정(+)의 영향을 미칠 것이라는 가설 2도 채택되었다. 이러한 분석 결과는 해운서비스기업이 다른 예선서비스기업으로 전환하는 비용이 높을수록 기존 예선서비스기업과 계속 거래할 가능성이 높아진다는 것을 의미한다. 넷째, 지각된 해운서비스기업의 관계혜택은 고객충성도에 정(+)의 영향을 미칠 것이라는 가설 3도 채택되었다. 본 연구는 관계혜택과 전환장벽, 고객충성도의 개념을 예선서비스기업에 적용하여 실증한 탐색적 연구이다. 특정지역의 해운선사 및 대리점 등 해운서비스기업 종사자를 표본으로 선정함에 따라 표본의 수가 부족한 한계점을 가지고 있다. 따라서 향후 연구에서는 예인서비스기업의 관계 혜택과 전환장벽, 고객충성도를 보다 정확하게 측정할 수 있는 정밀한 측정 도구를 개발할 필요가 있으며, 대상지역의 확대가 필요하다.