• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3A
• /
• pp.232-239
• /
• 2006

In this paper, we analyze the preamble model for Wireless PAN(WPAN) in proposed Ultra WideBand(UWB) Multi-Band OFDM(MB-OFDM) system of IEEE 802.15.3a standard. Besides, we propose effective Carrier Frequency Offset and Symbol Timing Offset Estimation algorithm which offers enhanced performance, and analyze its performance using Detection Probability, False Alarm Probability, Missing Probability, Mean Acquisition Time and MSE(Mean Square Error) through simulation in AWGN and UWB channel environments.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.3
• /
• pp.538-543
• /
• 2011

In this paper, design and control of an interleaved boost converter for multi-string PV Inverter are discussed. Interleaved Boost converter can reduce current ripples at input and output side by cancelling an each phase of inductor currents. Therefore, it contributes to increase efficiency and downsize the whole system volume, cost. One of the advantages of the multi-string system is easy to expand power capacity by connecting the converter modules in parallel. In order to reduce current ripples, the inductor currents on each phase are controlled independently in the converter module, and communication between the converter modules is required for further ripple current reduction. Current control algorithm for the balance of the each phase ripple currents and synchronization of the converter modules based on communication are proposed and implemented in the DSP programming. 10kW prototype of the multi-string converter module is assembled and experimental results are presented to verify the proposed ripple current reduction methods.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.501-505
• /
• 2001

The parallel operation system of UPS is used to increase reliability of power source at critical load. But parallel UPS system has a few defects, impedance is different from each other and circulating current occurs between UPSs, due to line impedance and parameter variation, though controlled by the same synchronization signal. According to such characteristic of parallel UPS, balanced load-sharing control is the most important technique in parallel UPS operation. In this paper, a novel power deviation compensation algorithm is proposed. it is composed of voltage controller to compensate power deviation that be calculated by using active and reactive current deviation between inverters on synchronous d-q reference frame.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.6
• /
• pp.600-606
• /
• 1992

The series connection of power switching semiconductor elements is essential when a high voltage converter is made, so researches are being conducted to further develop this technology. In the series connection of power switching semiconductor elements, the main problem is that simultaneous conduction at turn-on and simultaneous blocking at turn-off together with voltage balancing are unattainable because of the difference of their switching characteristics. In this paper a novel series connection algorithm is proposed, which can implement not only the synchronization of the points of turn-on and turn-off time but the dynamic voltage balancing in spite of the difference of each switching characteristics. The proposed method is that the compensated control signal is attained from the voltage feedback signal and applied to the series-connected power transistors independently. Computer simulation and experimental results verify its validity.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.720-723
• /
• 1996

The recent summer power peak crisis has been caused by excessive use of cooling loads at daily peak time in summer. The yearly load shape of KEPCO has gradually became very steep valley. Under this situation, more efficient DSM(Demand Side Management) tools are fully required for summer peak clipping and shaving. In this paper, the KEPCO's Jeju-Do model project for DSM, especially for Demand Controller, is presented. Demand Controller was evaluated to have the very high economical efficiency against the investment in equipment, as compared with another DSM tools. There were some serious problem to apply Demand Controller to many customers in the aspect to synchronization with KEPCO's watthour meter. But these problems have solved by Keyin's new Demand Controller using vision algorithm.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2002.04b
• /
• pp.1329-1332
• /
• 2002

최근 고속 통신망과 멀티미디어 기술의 급속한 발전으로 다양한 멀티미디어 서비스에 대한 연구와 그에 대한 응용 개발이 활발하게 이루어지고 있다. 그러나, 멀티미디어 응용 서비스는 기존의 단일미디어 서비스와는 달리 다양한 미디어의 통합된 전송을 필요로 하며, 개별 미디어의 정확한 연속성 및 관련된 미디어들 간의 적절한 시간적 동기화가 확보된 실시간 재생이 요구되는 고도화된 처리 기술을 필요로 하기 때문에 멀티미디어 동기화 알고리즘에 대한 연구는 필수적이고 매우 중요하다고 볼 수 있다. 본 논문은 Multimedia Data Streaming 을 위한 미디어 동기 방식 제어 알고리즘 고안 및 Lip Sync 방식 설계에 그 연구 목적이 있다.

• Journal of the Korean Society of Safety
• /
• v.11 no.1
• /
• pp.60-66
• /
• 1996

As the recently proposed JTC has been proven to be effective for implementation of real-time target tracking system, the interest on the electronic support system for the real-time JTC tracker has been increased. Accordingly, we proposed a tracking system which is based on BPEJTC and adaptive the fixed site. But because the EOTS is generally needed in the moving site such as aircraft and vehicles, and there are many different tracking algorithm to adopt the BPEJTC, we present an advanced version of BPEJTC dniver which has synchronization input so as to be used for the target pointer. In addition to the designed system architecture, some experimental results conducted by this system are illustrated.

• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.61-62
• /
• 2015

본 논문에서는 단상 UPS 모듈을 직렬로 연결 시 모듈간의 위상을 동기화하는 제어 알고리즘을 제안한다. 단상 직렬 모듈 UPS 시스템을 구성할 때, 각 모듈의 위상이 동기화 되어 있지 않는다면 직렬 연결된 출력단을 통해 부하에 불안정한 전력을 공급하게 된다. 따라서 직렬 구성으로 각 모듈의 출력전압 위상을 동기화하여 안정적인 출력전압 제어가 필요하다. 기존에는 CAN통신을 이용했지만 본 논문에서는, Master, Slave 모듈의 PLL 기법을 이용한 순차적인 제어를 통해 위상을 동기화시킬 수 있는 제어 알고리즘을 제안한다. 제안하는 제어 알고리즘은 시뮬레이션을 통해 타당성을 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2015.04a
• /
• pp.626-628
• /
• 2015

빅 데이터의 시대가 도래 하면서 데이터의 양이 기하급수적으로 증가 하고 있으며, 이에 따라 데이터를 효율적으로 처리하는 기술의 중요성이 부각 되고 있다. 데이터를 효율적으로 처리하기 위한 기술 중 하나인, 데이터 중복제거 기술은 저장 시스템 공간을 효율적으로 사용 할 수 있게 할 뿐만 아니라, 네트워크 환경에서 전송되는 데이터의 양도 획기적으로 줄여 주어 통신비용을 절감하게 한다. 기존의 데이터 중복제거 기술과 데이터 동기화 기법을 분석하고, 이를 바탕으로 클라우드 환경에서 데이터 중복제거를 통한 효율적인 데이터 동기화 기법을 제안하고자 한다.

• Proceedings of the KIPE Conference
• /
• 2019.07a
• /
• pp.380-381
• /
• 2019

This paper presents a grid voltage-sensorless current control design for an LCL-filtered grid-connected inverter with the purpose of enhancing the reliability and reducing the total cost of system. A disturbance observer based on the gradient steepest descent method is adopted to estimate the grid voltages with high accuracy and light computational burden even under distorted grid conditions. The grid fundamental components are effectively extracted from the estimated gird voltages by means of a least-squares algorithm to facilitate the synchronization process without using the conventional phase-locked loop. Finally, the estimated states of inverter system obtained by a discrete current-type full state observer are utilized in the state feedback current controller to realize a stable voltage-sensorless current control scheme. The effectiveness of the proposed scheme is validated through the simulation results.