• 전력전자학회논문지
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• 제19권3호
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• pp.240-248
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• 2014

It is DC power that Output of renewable energy being recently developed and researched. Also, demand of DC power will expect to proliferate due to increase of digital load. Thus, DC distribution system providing high quality of power and reliability has emerged as a new distribution system. If the conventional distribution systems are substituted by proposed DC distribution system, the output of renewable energy can be connected with distribution systems under minimum power conversion. Therefore, in the event of connection with DC load, it can construct an efficient distribution system. In this paper, the integrated parallel operation of power conversion module for DC distribution system is proposed. Also, this paper proposed modularization of power conversion devices for DC distribution system and power control for parallel operation of large capacity system. DC distribution system consists of three power conversion modules such as AC/DC power conversion module 2 set, ESS module 1 set. DC distribution system controls suitable operation depending on the status of the DC power distribution system and load. Integrated operation of these systems is verified by simulation and experiment results.

• 경영정보학연구
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• 제16권3호
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• pp.49-68
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• 2014

대다수의 국내외 온라인 디지털 음원 유통 사이트들은 음원 판매 활성화 방책의 일환으로 음원 추천시스템을 가지고 있다. 국외의 경우와 다르게, 우리나라의 시장점유율이 가장 높은 온라인 디지털음원 유통 사이트 5곳은 독자적인 기준으로 추천 음원을 선정하고 있으며, 추전 음원의 선정 기준 및 절차를 소비자에게 공개하고 있지 않다. 본 연구는 국내 온라인 디지털 음원 유통 사이트가 보유한 음원 추천시스템의 공정성 여부를 확인하고, 이러한 음원 추천시스템으로부터 선정된 추천 음원이 음원차트에서 어떠한 영향력을 갖는지 확인하는 것을 목적으로 한다. 2012년 11월부터 약 한달 간 온라인 디지털 음원 유통 사이트의 일간 음원차트에 등록되어 있는 1위부터 100위까지의 음원과 추천 음원을 수집하였다. 먼저, 수집된 음원 데이터를 기반으로 음원 추천시스템의 공정성 여부를 실증적인 방법으로 확인하였다. 첫째, 추천 음원의 노출 위치를 분석하였으며 둘째, 추천 음원이 제공되는 서비스 구조를 확인하였다. 셋째, 기획사에 따른 추천 음원 분포를 확인하였다. 더 나아가 이러한 음원 추천시스템으로부터 선정된 추천 음원이 음원차트 내에서 어떠한 영향력을 갖는지 실증적인 분석 방법으로 확인 하였다. 첫째, 음원차트의 동일 비동일 진입 시기에 따라 추천 음원과 미추천 음원의 순위 변화를 비교 분석하였다. 둘째, 모든 사이트에서 동시에 중복 추천된 음원과 단일 추천된 음원의 순위 변화를 비교 분석하였다. 셋째, 추천 받은 음원이 음원차트에 처음으로 진입하는 시기 및 순위를 확인하였다. 넷째, 음원차트 상위권 순위에 분포되어 있는 추천 음원의 비율을 확인하였다. 본 연구는 국내 온라인 디지털 음원 유통 사이트가 보유한 음원 추천시스템의 현행 및 현상에 대해 실증적으로 분석하여 공정성 문제를 제기하였으며, 음원 추천시스템이 음원차트에 미치는 파급력을 확인하였다는 것에 학술적 의의를 가진다. 또한 온라인 디지털 음원 유통 사이트의 내 외부 이해관계자에게 음원 추천시스템 악용에 대한 경각심을 고취시켜 음원차트의 공정성을 확보하고자하는 것에 산업적 의의를 가진다.

• 한국항행학회논문지
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• 제21권4호
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• pp.359-364
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• 2017

현재 아날로그 방식의 마을방송 시스템은 기술 적용의 문제 및 시설 노후화로 인한 성능 저하 등의 문제로 인하여 무선 디지털 시스템으로의 전환과 이에 따른 시스템 표준이 요구되고 있다. 그러나 주파수 부족으로 인해 효율적인 디지털 무선 마을 방송 시스템의 구축을 위해서는 이웃마을간의 간섭분석이 중요하므로 여기서는 대표적인 간이무선국 dPMR(digital private mobile radio) 및 DMR(digital mobile radio) 방식을 고려하여 동일채널 간섭과 인접채널 간섭에 대한 시뮬레이션을 수행하였다. 동일채널 간섭분석에서는 마을간 이격거리와 인접채널 간섭분석에서는 주파수 오프셋을 사용하여 주파수 재사용 및 채널분리에 대한 본 논문의 결과는 향후 마을방송 표준개발과 시범 사업화를 위한 자료로 활용될 것이다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.304-306
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• 2003

In this paper, we propose the intelligent robot control technique for mobile robot using personal digital assistants (PDA). With the proposed technique, the mobile rebot can trace human at regular intervals by the remote control method with PDA. The mobile robot can recognize the distances between it and human whom the robot must follow with both multi-ultrasonic sensors and PC-camera and then, can inference the direction and velocity of itself to keep the given regular distances. In the first place, the mobile robot acquires the information about circumstances using ultrasonic sensor and PC-camera then secondly, transmits the data to PDA using wireless LAN communication. Finally, PDA recognizes the status of circumstances using the fuzzy logic and neural network and gives the command to mobile robot again.

• 디지털산업정보학회논문지
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• 제13권4호
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• pp.153-162
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• 2017

Advances in communication technologies and the decreasing cost of computers have made distributed computer systems an attractive alternative for satisfying the information needs of large organizations. This paper presents a distributed algorithm for performance improvement through load balancing and file migration in distributed systems. We employed a sender initiated strategy for task migration and used learning automata with several internal states for file migration. A task can be migrated according to the load information of a computer. A file is migrated to the destination processor when it is in the right boundary state. We also described an analytical model for load balancing with file migration to verify the proposed algorithm. Analytical and simulation results show that our algorithm is very well-suited for distributed system environments.

• 제어로봇시스템학회논문지
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• 제6권3호
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• pp.235-240
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• 2000

In this paper a digital-control algorithm of a power system suing a high-speed PWM for a MRI system is proposed. The MRI system requires an elaborate ladder-shaped current source. And the load of current source is the inductance with resistance. For the inductive load a voltage output of the power system has hi호 frequency components. Therefore this system requires high-speed PWM above 80KHz, A high speed PWM control algorithm which satisfies those conditions is designed. Finally the performance of proposed control algorithm is shown by simulation.

• 제어로봇시스템학회논문지
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• 제18권1호
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• pp.13-20
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• 2012

This paper proposes a marine engine state monitoring system using a DPQ (Distributed Precedence Queue) mechanism which collects the state of bearings, temperature and pressure of engine through the CAN network. The CAN is developed by Bosch Corp. in the early 1980' for automobile network. The data from various sensors attached in the marine engine are converted to digital by the analog to digital converter and formatted to fit the CAN protocol at the CAN module. All the CAN modules are connected to the SPU (Signal Processing Unit) module for the efficient communication and processing. This design reduces the cost for wiring and improves the data transmission reliability by recognizing the sensor errors and data transmission errors. The DPQ mechanism is newly developed for the performance improvement of the marine engine system, which is demonstrated through the experiments.

• 디지털산업정보학회논문지
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• 제7권1호
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• pp.11-18
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• 2011

A mobile agent system is the most common software paradigm for distributed applications. A software development model to develop efficiently for these systems is needed. Unified Modeling Language (UML) is a widely used software development model to develop a system for Visualizing, Specifying, Constructing, Documenting. However, UML can not describe in explicit way the necessary mobility of the mobile agent-based software systems. In this paper, the interaction diagrams of UML (sequence diagrams and communication diagrams) are extended and used to express the mobility of the mobile agents in three ways. For a case study, we applied the extended diagrams to a distributed file searching using mobile agents, and showed these diagrams can describe the mobility very well.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.912-917
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• 2006

A strain gauge weight measuring instrumentation system was designed with RF sensor network facilities. In the sensor module system data conversion and a series of signal processing were totally equipped. 16 strain gauges are incoming sensors and each output of the strain gauge was amplified and filtered for proper analog signal processing. Several measuring instrumentation OP amps and general purposed OP amps were used. 12 bits A/D converters converted analog signals to digital bits and a PIC microprocessor controlled the 16 channels of strain gauges. RF RS232 modules were used for wireless communication between the PIC microprocessor and an Ethernet host far a remote sensor monitoring system development.

• ETRI Journal
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• 제41권1호
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• pp.32-41
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• 2019

We propose a speckle reduction technique in electronic holographic display systems, where digital micro-mirror array devices are used as spatial light modulators. By adopting a programmable filtration in a general 4-f optic configuration, it is shown that the signal spectrum components in the frequency domain of a viewing-window-based holographic display system can be selectively filtered. Compared to the widely utilized single-sideband filtration techniques in electronic holographic display systems, our proposed programmable filtration can be utilized to effectively reduce the speckles in the reconstruction of point-cloud-based computer-generated holograms. Experimental results are presented to verify our proposed concept.