• 정보처리학회논문지D
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• 제13D권3호
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• pp.445-454
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• 2006

구형 산업용 계측 장비들은 대부분 직렬 통신 기능만 갖추고 있다. 이러한 장비들을 인터넷으로 연결하기 위한 임베디드 통신 변환기를 구현하였다. 이 장비는 입출력 장치로 한 개의 WAN 포트, 두 개의 LAN 포트, 두 개의 직렬 포트를 갖고 있으며, 소프트웨어에 의하여 직렬 통신과 네트워크 통신 간의 상호 변환 기능을 수행하고, 기존의 직렬-이더넷 변환기와 구별되는 웹 모니터링 기능을 지원한다. ARM922T를 프로세서 코어를 사용하는 MICREL 사의 KS8695 네트워크 전용 칩셋을 사용하여 하드웨어를 구현하였고, 인터넷 기반 원격 제어를 위하여 웹 서버인 boa와 CGI 기능을 활용하였으며, 사설 IP 주소를 갖는 네트워크에서도 인터넷 접속이 가능하도록 IP 공유 기능을 추가하였으며, 통신 변환기의 역할을 수행하는 직렬-이더넷 변환 프로그램을 개발하였다. 그리고 개발된 통신 변환기를 태양열 에너지 전력 생산시스템의 원격 감시 장치로 활용하는 예를 제시하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권12호
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• pp.4946-4960
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• 2020

In a device-to-device (D2D) underlaid cellular network, there exist two types of co-channel interference. One type is inter-layer interference caused by spectrum reuse between D2D transmitters and cellular users (CUEs). Another type is intra-layer interference caused by spectrum sharing among D2D pairs. To mitigate the inter-layer interference, we first derive the interference limited area (ILA) to protect the coverage probability of cellular users by modeling D2D users' location as a Poisson point process, where a D2D transmitter is allowed to reuse the spectrum of the CUE only if the D2D transmitter is outside the ILA of the CUE. To coordinate the intra-layer interference, the spectrum sharing criterion of D2D pairs is derived based on the (signal-to-interference ratio) SIR requirement of D2D communication. Based on this criterion, D2D pairs are allowed to share the spectrum when one D2D pair is far from another sufficiently. Furthermore, to maximize the energy efficiency of the system, a resource allocation scheme is proposed according to weighted graph coloring theory and the proposed ILA restriction. Simulation results show that our proposed scheme provides significant performance gains over the conventional scheme and the random allocation scheme.

• 한국물환경학회지
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• 제37권6호
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• pp.493-500
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• 2021

Floating solar photovoltaic (hereinafter PV) power generation is emerging as a proper alternative to overcome various environmental limitations of existing offshore PV generation. However, more government-led policy design and technical and institutional development are still required. Based on the policy agenda setting theory and technological innovation theory, this study contains the research questions concerning the co-evolution of technology and the floating solar PV policy. This study primarily evaluates the technological and institutional development level of floating solar PV policy through a survey of domestic floating solar PV experts. Secondly, we also analyze the kind of policy agenda that should be set a priori. Analyzing the priorities to be considered, the first environmental enhancement needs to be considered from both the technical and institutional aspects. The second candidate task for the policy agenda is residents' conflict and improvement of regulations. Both candidate tasks need to be actively considered in the policy agenda from the institutional point of view. The third is publicity, profit sharing, follow-up monitoring, and cost. Among them, public relations and profit sharing are tasks that need to be considered in the policy agenda from the institutional point of view. On the other hand, the cost of follow-up monitoring should be considered as a policy agenda in terms of technology, system, and common aspects. Finally, there are technical standards. Likewise, technical standards need to be considered in the policy agenda in terms of both technical and institutional commonality.

• 한국해양바이오학회지
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• 제1권1호
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• pp.34-39
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• 2006

Molecular biology and microalgal biotechnology have the potential to play a major role in improving the production efficiency of a vast variety of products including functional foods, industrial chemicals, compounds with therapeutic applications and bioremediation solutions from a virtually untapped source. Microalgae are a source of natural products and have been recently studied for biotechnological applications. Efficient genetic transformation systems in microalgae are necessary to enhance their potential to be used for human health. A microalga such as Chlarella is a eukaryotic organism sharing its metabolic pathways with higher plants. This microalga is capable of expressing, glycosylating, and correctly processing proteins which normally undergo post-translational modification. Moreover, it can be cultured inexpensively because it requires only limited amount of sunlight and carbon dioxide as energy sources. Because of these advantages, Chlarella may be of great potential interest in biotechnology as a good candidate for bioreactor in the production of pharmaceutical and industrial compounds for human functional foods. Here, we briefly discuss recent progress in microalgal transgenesis that has utilized molecular biology to produce functional proteins and bioactive compounds.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.187-190
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• 2005

Ultra wideband (UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geolocation, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional mobile wireless systems sharing the frequency bands such as WCDMA system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a direct-sequence spread-spectrum UWB source and an impulse radio UWB source, to a WCDMA digital transmission system. The average frame error rate degradations are presented. From these experimental results, we show that in all practical cases UWB system can coexist with WCDMA terminal without causing any dangerous interference.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.432-434
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• 1994

This paper describes a phase-shifter which can flexibly adjust the active and reactive power flow through an ac transmission line. The phase-shifter has two voltage-source converters sharing an energy storage capacitor. The magnitude of the injected voltage is controlled by the converter I connected in parallel with the sending terminal, while that of phase angle by the converter II in series with the line through the coupling transformer. In order to analyze the whole system operation, an equivalent circuit model was developed and verified by a computer simulation with EMTP code.

• Journal of Power Electronics
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• 제9권3호
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• pp.410-417
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• 2009

This paper represents a design and implementation of a digital controller for a multi-phase synchronous buck converter (SBC) using a digital signal processor (DSP). The multi-phase SBC has generally been used for a voltage regulation module (VRM) of a microprocessor because of its high current handling capability at a low output voltage. The VRM requires high control performance of tight output regulation, high slew rate, and load sharing capability of multiple converters. In order to achieve these requirements, the design and implementation of a digital control system for a multi-phase SBC are presented in this paper. The digital PWM generation, current sensing, and voltage and current controller using a DSP TMS320F2812 are considered. The experimental results are provided to show the validity of the implemented digital control system.

• 한국컴퓨터정보학회논문지
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• 제22권8호
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• pp.41-46
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• 2017

In this paper, we investigate the D2D Transmitter(Tx) and Receiver(Rx) pair assignment problem in the cellular system where D2D users share the uplink resource of the cellular system. Sharing the uplink resource of the cellular system may cause interference to the cellular system, though it is beneficial to improve the D2D user Capacity. Therefore, to protect the cellular users, D2D transmit power should be carefully controlled. In this work, we focus on optimal Tx-Rx assignment in such a way that the total transmit power of users is minimized. First, we consider the optimum Tx-Rx assignment in general and the corresponding complexity. Then, we propose an iterative D2D Tx-Rx assignment algorithm with low complexity that can minimize total transmit power of users. Finally, we present the numerical examples that show the complexity and the convergence to the unique transmit power level.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.255-258
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• 2007

In this paper, a PV multi-string PCS with a grid-connection is proposed. An improved MPPT algorithm for the PV multi-string PCS is suggested. Each PV string has its own MPP tracker and the proposed MPPT algorithm prevents LMPP tracking due to power ripple. In the PV PCS with single-phase inverter has a large current ripple at twice the grid frequency. The current ripple reduction algorithm without external component is suggested. Also, this paper proposes a simple control method to achieve sharing of the PV string voltage and current among the interleaved parallel boost converters. All algorithms and controllers are implemented on a single-chip microcontroller. Experimental results obtained on a 3kW prototype show high performance of the proposed PV multi-string PCS.

• 대한전기학회논문지:전력기술부문A
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• 제49권6호
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• pp.272-279
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• 2000

This paper describes a controller design and dynamic performance analysis of UPFC based on 3-level inverters. Major attention is focused on the controller design for both shunt and series inverters, including regulator design for the dc link voltage sharing across the dc capacitors. An energy-based approach was investigated for effectively designing the controller. A detailed UPFC model has been developed with EMTP using 24-pulse 3-level inverters to verify this approach. Simulation results about dynamic performance of UPFC confirm effects for increasing transmission capacity and damping low-frequency oscillation. The developed simulation model would be very effective to analyze the dynamic performance of UPFC.