• 한국통신학회논문지
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• 제28권12A호
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• pp.983-990
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• 2003

본 논문에서는 3GPP 모뎀용 비동기식 동기추적회로(noncoherent code tracking loop)를 설계하고 설계된 회로의 정상상태 지터 분산(steady-state jitter variance)과 과도응답 특성(transient response characterisitc)을 해석한다. 먼저, AWGN 환경에서의 지터 분산을 펄스성형 필터(pulse-shaping filter), 타이밍 오프셋(timing offset), 신호 대잡음비(signal-to-interference ratio), 루우프 대역폭(loop bandwidth)에 대한 일반식으로 유도하고, 과도응답 특성을 이론적으로 해석한다. 이를 바탕으로, 디지털 하드웨어 구현이 용이한 가변 대역폭 동기추적회로를 설계하며 설계된 회로와 고정 대역폭 시스템의 성능을 이론적으로 비교, 분석하고 컴퓨터 시뮬레이션을 통해 검증한다.

• 한국안전학회지
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• 제36권5호
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• pp.10-17
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• 2021

The controversy over the risk of the human body being affected by electromagnetic fields emitted from 60 Hz power lines continues without end. There are currently no new studies or research progress being made in this direction that is notable, and the number of civil complaints is gradually increasing. The problem is that each study produces different results, among which the effect of exposure to magnetic fields on childhood leukemia is a major one. In Korea, an electrician who was maintaining a 22.9 kV power line died of leukemia, which has recently been recognized as an occupational disease. Methods to reduce magnetic fields from power lines include shielding with wire loops, incorporating split phases and compaction techniques, installing underground power lines, converting to high-voltage direct current (HVDC), and increasing the ground clearance of transmission towers. Depending on whether a separate power supply is needed or not, there are two types of wire loops: passive loop and active loop. Magnetic field reduction is currently done through underground power lines; however, the disadvantage of this process is high construction costs. Installing passive loops, with relatively low construction costs, leads to lower magnetic field reduction rates than installing underground cables and a weakness to not solving the landscape problem. This methodological study aims at designing methods and reducing the effects of 2-wire set loops-the simplest and most practical. Since the method proposed in this study has been designed after analyzing the distribution of complex electromagnetic fields near the expected loop installation location, a practical design can be implemented without the need for any difficult optimization programming.

• 전자공학회논문지
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• 제51권1호
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• pp.90-96
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• 2014

본 논문은 광대역 특성의 뱅뱅 디지털 위상 동기 루프를 설계함에 있어 최적의 루프 이득 선정을 통한 실용적인 선형화 설계 기법을 제안한다. 기존의 이론적 파라미터 설계 기법을 광대역 클럭 발생기 회로에 적용함에 있어 한계점을 설명하고 실제 구현된 뱅뱅 디지털 위상 동기 루프 설계에 대해서 살펴보았다. 본 논문에서는 정수 어레이와 디더 이득은 크게 하되 비례 이득을 작게 설정하여 뱅뱅 디지털 위상 동기 루프의 리미티드 사이클 노이즈를 제거하였다. 제안된 설계 기법을 적용한 뱅뱅 디지털 위상 동기 루프는 기존의 구조에 비교하여 초소형, 저전력, 선형 특성 및 루프 대역폭 조절이 가능한 장점을 보이며, 성능의 우수성을 시뮬레이션을 통하여 검증하였다.

• Journal of Power Electronics
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• 제10권5호
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• pp.518-527
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• 2010

This paper presents a new technique for directly designing a linear digital controller for a single-phase pulse width modulation (PWM) converter systems, based on closed-loop identification. The design procedure consists of three steps. First, obtain a digital current controller for the inner loop system by using the error space approach, so that the power factor of the supply is close to one. The outer loop is composed of a voltage controller, a current control loop including a current controller, a PWM converter, and a capacitor. Then, all the components, except the voltage controller, are identified by a discrete-time equivalent linear model, using the closed-loop output error (CLOE) method. Based on this equivalent model, a proper digital voltage controller is then directly designed. It is shown through PSim simulations and experimental results that the proposed method is useful for the practical design of PWM converter controllers.

• Nuclear Engineering and Technology
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• 제40권2호
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• pp.127-132
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• 2008

An experimental loop operating with water at supercritical conditions(25MPa, $600^{\circ}C$ in the test section) is designed for operation in the research reactor LVR-15 in UJV Rez, Czech Republic. The loop should serve as an experimental facility for corrosion tests of materials for in-core as well as out-of-core structures, for testing and optimization of suitable water chemistry for a future HPLWR and for studies of radiolysis of water at supercritical conditions, which remains the domain where very few experimental data are available. At present, final necessary calculations(thermalhydraulic, neutronic, strength) are being performed on the irradiation channel, which is the most challenging part of the loop. The concept of the primary and auxiliary circuits has been completed. The design of the loop shall be finished in the course of the year 2007 to start the construction, out-of-pile testing to verify proper functioning of all systems and as such to be ready for in-pile tests by the end of the HPLWR Phase 2 European project by the end of 2009.

• Journal of Power Electronics
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• 제19권4호
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• pp.869-880
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• 2019

Due to the inherent feedforward of load current, capacitor current (CC) control shows a fast transient response that makes it suitable for the power supplies used in various portable electronic devices. However, considering the effect of the outer voltage loop, the stable range of the duty-cycle is significantly diminished in CC controlled buck converters. To investigate the stability effect of the outer voltage loop on buck converters, a CC controlled buck converter with a proportion-integral (PI) compensator is taken as an example, and its second-order discrete-time model is established. Based on this model, the instability caused by the duty-cycle is discussed with consideration of the outer voltage loop. Then the dynamical effects of the feedback gain of the PI compensator and the equivalent series resistance (ESR) of the output capacitor on the CC controlled buck converter with a PI compensator are studied. Furthermore, the design-oriented closed-loop stability criterion is derived. Finally, PSIM simulations and experimental results are supplied to verify the theoretical analyses.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.315-318
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• 1999

The purpose of this study is to establish the design theory of a DR ceramic bandpass filter used for WLL basestations and to research on the design theory of bandpass filter. The design procedure is circuit parameters and structural parameters will be derived. It was observed that the filter characteristics at the simulations

• 대한안전경영과학회지
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• 제14권2호
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• pp.49-54
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• 2012

As all kind of industry has developed, metal structure and machine instrument use bolt, pin, rivet and welding for assembly and combination. For pin and hinge, dimension accuracy is crucial to keep the operation and safety of the structure and machine instrument. In case of complex machine, the hinge for cover open-loop system is one of the significant design elements. Most of the hinges are being imported and assembled sine they give high technology development cost for its unit cost position. The reason is that the localization of hinge is inadequate. As the demand increase and the necessity of localization grow, it is now more important than ever to develop low cost structure. By the low cost structure, a new technology could be obtained for electronic product and structural hinge since it would enable for complex machine hinge to be guaranteed, technologically. Open-loop hinge is the link type and designed for the structure to keep constant open-loop. And, the hinge is examined in design stability by finite element analysis method. In this paper, the operation result is presented when the hinge for complex machine open-loop is designed for link type structure.

• 한국통신학회논문지
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• 제16권10호
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• pp.981-991
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• 1991

LQG의 강인성 증진을 위하여 제안된 LGQ/LTR방법은 비 최소위상 플랜트에 대하여 적용할 수 없는 이론적 제한성을 갖는다. 본 논문에서는 비 최소위상 플랜트에 대해서도 적용될 수 있는 세 단계로 구성된 새로운 LQG/LTR방법을 제안한다. 첫번째 단계로 주어진 비 최소위상 플랜트를 최소위상 플랜트로 근사화 시키기 위한 부가적인 feed-forward 보상기를 설계하며 다음 단계에서 전개사양에 맞도록 근사화된 비 최소위상 플랜트에 대하여 목표 루우프를 설계한다. 마지막 단계로 개루우프의 전달함수가 목표 루우프로 회복시키는 LTR을 설계한다. 제안된 방법이 비 최소위상 플랜트에 대한 제약을 해결할 수 있음을 시뮬레이션 예제를 통하여 보인다.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1134-1145
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• 2021

A design parameter study is presented for the closed-loop type passive containment cooling system (PCCS) which is equipped with two heat exchangers: one installed at the inside of the containment and the other submerged in the water pool at the outside of the containment. A GOTHIC code model for PCCS performance analyses was set up and the design parameters such as the heat exchanger sizes, locations, and water pool tank volumes were analyzed to investigate the feasibility of installing this type of PCCS in PWRs like OPR-1000 being operated in Korea. We identified the size of the circulation loop and heat exchangers as major design parameters affecting the performance of PCCS. The analyses showed that the heat exchangers in the inside of the containment would be more influential on the heat removal capability of PCCS than that installed in the water pool at the outside of the containment. Hence, it was recommended to down-size the heat exchangers in the water pool to optimize PCCS without compromising its performance. Based on the parametric study, it was demonstrated that a closed-loop type PCCS could be designed sufficiently compact for installation in the available space within the containment of PWRs like OPR-1000.