• 정보처리학회논문지A
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• 제8A권3호
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• pp.261-268
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• 2001

With the rapid growth of the Internet, various web-based businesses are creating a new environment in an imaginary space. However, this expanding Internet and user increase cause an overflow of transmission and numerous subordinate problems. To solve these problems, a parallel cluster system is produced using different methods. This thesis recommends a multi0distribution cluster group. It constructs a MPP dynamic distribution sub-cluster group using numerous low-priced and low-speed systems. This constructed sub-cluster group is then connected with a singular virtual IP to finally serve the needs of clients (users). This multi-distribution cluster group consists of an upper structure based on LVS and a dynamic serve cluster group centered around an SC-server. It conducts the workloads required from users in a parallel process. In addition to the web service, this multi-distribution cluster group can efficiently be utilized for the calculations which require database controls and a great number of parallel calculations as well as additional controls with result from the congestion of service.

• Journal of Power Electronics
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• 제9권2호
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• pp.133-145
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• 2009

In this paper a modular high performance MV-to-LV rectifier based on a cascaded H-bridge rectifier is presented. The proposed rectifier can directly connect to the medium voltage levels and provide a low-voltage and highly-stable DC interface with the consumer applications. The input stage eliminates the necessity for heavy and bulky step-down transformers. It corrects the input power factor and maintains the voltage balance among the individual DC buses. The second stage includes the high frequency parallel-output DC/DC converters which prepares the galvanic isolation, regulates the output voltage, and attenuates the low frequency voltage ripple ($2f_{line}$) generated by the first stage. The parallel-output converters can work in interleaving mode and the active load-current sharing technique is utilized to balance the load power among them. The detailed analysis for modeling and control of the proposed structure is presented. The validity and performance of the proposed topology is verified by simulation and experimental results.

• Journal of Communications and Networks
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• 제13권3호
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• pp.277-285
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• 2011

Real-time multimedia streaming over the Internet is rapidly increasing with the popularity of user-created contents, Web 2.0 trends, and P2P (peer-to-peer) delivery support. While many homes today are broadband-enabled, the quality of experience (QoE) of a user is still limited due to frequent interruption of media playout. The vulnerability of TCP (transmission control protocol), the popular transport-layer protocol for streaming in practice, to the packet losses, retransmissions, and timeouts makes it hard to deliver a timely and persistent flow of packets for online multimedia contents. This paper presents TCP-real-time online multimedia environment (ROME), a novel transport-layer framework that allows the establishment and coordination of multiple many-to-one TCP connections. Between one client with multiple home addresses and multiple co-located or distributed servers, TCP-ROME increases the total throughput by aggregating the resources of multiple TCP connections. It also overcomes the bandwidth fluctuations of network bottlenecks by dynamically coordinating the streams of contents from multiple servers and by adapting the streaming rate of all connections to match the bandwidth requirement of the target video.

• 한국재료학회지
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• 제15권11호
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• pp.690-696
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• 2005

The ultrastructure ore of a nanostructured apatite film nucleated from solution was studied to gain insights into that of bone minerals which is the most important constituent to sustain the strength of bones. Needle-shaped apatite crystal plates with a bimodal size distribution $(\~100\;to\;\~1000 nm)$ were randomly distributed and they were found to grow parallel to the c-axis ([002]), driven by the reduction of surface energy. Between these randomly distributed needle-shaped apatite crystals which are parallel to the film, apatite crystals (20-40nm) with the normal of the grains quasi-perpendicular to the c-axis were observed. These observations suggest that the apatite film is the interwoven structure of apatite crystals with the c-axis parallel and quasi-perpendicular to the fan. In some regions, amorphous calcium phosphate, which is a precursor of apatite, was also observed. In the amorphous phase, small crystalline particle with the size of 2-3 nm were observed. These particles were quite similar, in size and shape, to those observed in the femoral trabecular bone, suggesting the nucleation of apatites by a biomimetic process in vitro is similar to that in vivo.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제5권6호
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• pp.793-800
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• 1999

TMN Agent Platform은 망 요소의 운영상태와 자원들을 GDMO에 따라 관리객체(Managed Object : MO)로 모델링 하고, 자원들의 현재 상태를 유지하며, 관리자(Manager)로부터의 망 관리 기능 요구에 따라 조작된다. 그러므로, 에이전트의 성능향상은 전체적인 통신망 관리의 성능향상에 직접적인 영향을 미친다.본 논문에서는 TMN 에이전트의 기능요구 사항을 분석하고, 이를 토대로 성능향상을 위해 멀티스레드 기법을 사용하는 병렬 처리 구조의 TMN Agent Platform의 기능구조를 제시한다. 또한 에이전트와 다양한 자원들간의 효율적인 메시지전달을 위한 체계를 제시하며, 구현된 TMN Agent Platform의 성능을 분석한다.Abstract TMN Agent manages the operational status and real-resources of network elements, such as switching nodes and transmission systems. It performs the requested management functions from manager and maintains consistent status data of real-resource. The performance of agent system affects directly the performance of network management operation. If the agent is implemented by sequential processing scheme with single process, the agent processing can be delayed or blocked according to the status of real-resources. This problem can be solved by parallel and distributed processing scheme.To improve the processing performance of TMN Agent, we propose a TMN Agent Platform's functional architecture that is based on parallel processing with multi-tread and effective message transferring scheme between agent and various real-resource. We analyze the performance of the implemented TMN Agent Platform.

• 한국전자통신학회논문지
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• 제17권1호
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• pp.119-124
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• 2022

성공적인 수중 위치측정을 위해서는 다양한 수중 로봇에 탑재 가능한 대규모 병렬 컴퓨팅 환경이 필요하다. 이에, 본 논문에서는 수중 위치측정을 위한 인공지능 컴퓨팅 플랫폼 설계 방법을 제안한다. 제안한 플랫폼은 총 4개의 하드웨어 모듈로 구성된다. Transponder 및 hydrophone 모듈은 음파를 송수신하며 FPGA 모듈은 송수신한 음파 신호를 빠르게 병렬로 전처리한다. Jetson 모듈은 인공지능 기반 알고리즘 처리한다. 해당 플랫폼은 실제 수중 환경에서 거리에 따라 수중 위치측정을 위한 음파 송수신 실험을 수행하였으며 이를 통해 설계한 플랫폼을 검증할 수 있었다.

• 전력전자학회논문지
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• 제27권2호
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• pp.92-99
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• 2022

Due to space and geographical constraints, the power source may be located outside the island area, resulting in the considerable length of transmission line. In these cases, when an active power is transmitted, unexpected reactive power is generated at a point of common coupling (PCC). Unlike the power transmitted from the power generation source, the reactive power adversely affects the system. This study proposes a new algorithm that controls reactive power at PCC. Causes of reactive power errors are separated into parallel and series components, which allows the algorithm to compensate the reactive current of the inverter output and control reactive power at the PCC through calculations from the impedance, voltage, and current. The proposed algorithm has economic advantages by controlling the reactive power with the inverter of the power source itself, and can flexibly control power against voltage and output variations. Through the simulation, the algorithm was verified by implementing a power source of 3 [kVA] capacity connected to the low voltage system and of 5 [MVA] capacity connected to the extra-high voltage system. Furthermore, a power source of 3 [kVA] capacity inverter is configured and connected to a mock grid, then confirmed through experiments.

• ETRI Journal
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• 제21권2호
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• pp.22-30
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• 1999

In this paper, we derive an efficient parallel algorithm to solve the single function coarsest partition problem. This algorithm runs in O(\log2n) time using O(nlogn) operations on the EREW PRAM with O(n) memory cells used. Compared with the previous PRAM algorithms that consume O(n1+${\varepsilon}$) memory cells for some positive constant ${\varepsilon}\>0$, our algorithm consumes less memory cells without increasing the total number of operations.

• IEIE Transactions on Smart Processing and Computing
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• 제5권1호
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• pp.29-34
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• 2016

A controller area network (CAN) controller is an integral part of an electronic control unit, particularly in an advanced driver assistance system application, and its characteristics should always be advantageous in all aspects of functionality especially in real time application. The cost should be low, while maintaining the functionality and reliability of the technology. However, a CAN protocol implementing serial operation results in slow throughput, especially in a cyclical redundancy checking (CRC) unit. In this paper, digital signal processing (DSP) algorithms are implemented, namely pipelining, unfolding, and retiming the CAN controller in the CRC unit, particularly for the encoder and decoder sections. It must attain a feasible iteration bound, a critical path that is appropriate for a CAN system, and must obtain a superior design of a high-speed parallel circuit for the CRC unit in order to have a faster transmission rate. The source code for the encoder and decoder was formulated in the Verilog hardware description language.

• 한국전자파학회지:전자파기술
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• 제3권2호
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• pp.16-21
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• 1992

플란지 평해도파관에 의한 TE-모드의 산란 및 수신을 해석한다. 푸리에 변환을 이요하여 주파수 영역에서 산란파를 표시하여, 경계조건을 사용하여 산란파의 점근해를 구하였다. 수치해석을 통하여 산란특성을 조사하였다.