• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.24-31
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• 2006

In the present study, a strongly coupled analysis code is developed for transonic flutter analysis. For aerodynamic analysis, two dimensional Reynolds-Averaged Navier-Stokes equation was used for governing equation, and ε-SST for turbulence model, DP-SGS(Data Parallel Symmetric Gauss Seidel) Algorithm for parallelization algorithm. 2 degree-of-freedom pitch and plunge model was used for structural analysis. To obtain flutter response in the time domain, dual time stepping method was applied to both flow and structure solver. Strongly coupled method was implemented by successive iteration of fluid-structure interaction in pseudo time step. Computed results show flutter speed boundaries and limit cycle oscillation phenomena in addition to typical flutter responses - damped, divergent and neutral responses. It is also found that the accuracy of transonic flutter analysis is strongly dependent on the methodology of fluid-structure interaction as well as on the choice of turbulence model.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.5
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• pp.196-208
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• 2005

In multiprocessor systems, interconnection network design is critical for overall system performance. Popular interconnection networks, which are generally considered, are meshes, rings, and hierarchical rings. In this paper, we propose (')Torus Ring('), which is a modified version of hierarchical ring. Torus Ring has the same complexity as the hierarchical rings, but the only difference is the way it connects the local rings. It has an advantage over the hierarchical rings when the destination of a packet is the neighbor local ring in the reverse direction. Though the average number of hops in Torus Ring is equal to that of the hierarchical rings when assuming the uniform distribution of each transaction, the benefits of the number of hops are expected to be larger because of the spatial locality in the real environment of parallel programming. In the simulation results, latencies in the interconnection network are reduced by up to 19$\%$, and the execution times are reduced by up to 10$\%$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.104-112
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• 2002

In this paper, it is suggested that the selection method of parameter of Power System Stabilizer(PSS) with robustness in low frequency oscillation for Thyristor Controlled Series Capacitor(TCSC) using Geletic Algorithm(GA). A TCSC meddle consists of a stories capacitor and a parallel path with a thyristor valve and a series inductor. Also in in parallel, as is typical with series capacitor applications, is a metal-oxide varistor(MOV) for overvoltage protection. The proposed PSS parameters are optimized using GA in order to maintain optimal operation of TCSC which is expected to be applied in transmission system to achieve a number of benefits under the various operating conditions. In order to verify the robustness of the proposed method, we considered the dynamic response of angular velocity deviation and terminal voltage deviation under a power fluctuation and rotor angle variation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.193-204
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• 2008

This paper describes laboratory experiments modelling multiple tunnel construction in soft ground. A series of small-scale model tests have been conducted at approximately 1/50 scale in order to investigate the behaviours of existing tunnels in response to the construction of new tunnels in close proximity. The model tunnels were constructed in a consolidated Speswhite Kaolin clay using a tunnelling device involving an auger type cutter within a shield. Strain gauges and LVDTs were used for instrumenting the existing tunnels. The findings obtained from the analyses of these tests were compared to the field measurements involving the reconstruction of the Northern Line London Underground Ltd. tunnels at Old street, United Kingdom. The results were also compared to the ground movement measurements obtained from a separate set of tests undertaken using the same apparatus and experimental procedures.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.4
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• pp.285-292
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• 2007

SoC which deploys software modules as well as hardware IPs on a single chip is a major revolution taking place in the implementation of a system design, and high-level synthesis is an important process of SoC design methodology. Recently, SPARK parallelizing high-level synthesis software tool has been developed. It takes a behavioral ANSI-C code as an input, schedules it using code motion and various code transformations, and then finally generates synthesizable RTL VHDL code. Although SPARK employs various loop transformation algorithms, the synthesis results generated by SPARK are not acceptable for basic signal and image processing algorithms with nested loop. In this paper we propose a SoC platform with an application-specific PLD targeting local operations which are feature of many loop algorithms used in signal and image processing, and demonstrate design process which maps behavioral specification with nested loops written in a high-level language (ANSI-C) onto 2D systolic array. Finally the derived systolic array is implemented on the proposed application-specific PLD of SoC platform.

• Information and Communications Magazine
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• v.9 no.11
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• pp.70-79
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• 1992

제6세대 컴퓨터로 불리는 신경컴퓨터는 학습과 병렬처리에 의해 인간의 두뇌 기능을 모방한다. 인간의 두뇌는 시각인식, 음성인식, 촉각감지 등 패턴인식뿐 아니라 인간의 복잡한 신체구조를 시각, 촉각 같은 감각기관의 도움을 얻어 움직이는 중요한 역할도 한다. 바로 이 모터제어(motor control) 역시 신경회로가 담당하기 때문에 이를 기계적 신체에 해당하는 로보트 또는 광범위하게 기계, 비행기, 산업공정에 응용하는 것은 매우 자연스럽게 보인다. 이처럼 신경회로가 제어에 응용되는 것을 신경제어 (neurocontrol)라 하고 이를 이용한 기계를 지능기계(intelligent machinery)라 한다. 지능기계는 기본적으로 인간처럼 경험축적 학습 불확실한 환경에서의 적응 자기진단 등의 장점을 가지고 있다. 신경회로의 지극히 광범위한 응용분야중 신경제어는 가장 먼저 실현될 가능성이 높다. 실제로 로보트나 공정제어(process control)처럼 복잡한 비선형 시스템의 제어는 다량의 센서 정보에 기초한 실시간 제어를 필수로 하며 이는 신경회로를 사용함으로써 가장 효율적, 경제적으로 구현할 수 있다. 실제로 신경제어는 전세계적으로 이미 시스템 제어에 응용되어 좋은 결과를 내고 있다. 신경회로의 로보트나 자동화 응용은 학술적인 측면에서는 복잡한 비선형 시스템의 지능제어 (intelligent control)문제에 대한 신선한 해결책을 마련해줄 뿐 아니라 산업자동화라는 막대한 시장을 뒤로 하고 있어 이론에서 실제에 걸쳐 가장 광범위한 파급효과를 가지는 최첨단 기술로 보여진다. 고부가가치 상품을 통한 국제 경쟁력 제고의 차원에서도 정부, 기업 등의 과감한 연구 개발투자가 선행되어야 한다. 특히 이 분야의 연구는 선진국도 최근에 시작한 점으로 보아 정부, 기업이 이에 대한 연구 개발투자를 현명하게 할 경우에 세계적 기술 경쟁력도 확보할 수 있을 것이다. 본 해설에서는 로보트 및 시스템 제어에 관한 기초 이론을 설명하고 신경회로 적용기술을 소개하고 기존 방법과 비교 했을 때의 우월성, 전세계적인 응용연구, 국내외 연구개발 현황, 상업화 가능성, 산업계 응용례, 기술상의 문제점, 향후 전망 등을 다루기로 한다.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.119-128
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• 2011

This paper introduces design space exploration of many-core processors that meet high performance and low power required by the beamforming algorithm of image signals of mobile ultrasound. For the design space exploration of the many-core processor, we mapped different number of ultrasound image data to each processing element of many-core, and then determined an optimal many-core processor architecture in terms of execution time, energy efficiency and area efficiency. Experimental results indicate that PE=4096 and 1024 provide the highest energy efficiency and area efficiency, respectively. In addition, PE=4096 achieves 46x and 10x better than TI DSP C6416, which is widely used for ultrasound image devices, in terms of energy efficiency and area efficiency, respectively.

• Journal of KIISE
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• v.43 no.4
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• pp.470-479
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• 2016

As the number of various types of media data such as UCC (User Created Contents) increases, research is actively being carried out in many different fields so as to provide meaningful media services. Amidst these studies, a semantic web-based media classification approach has been proposed; however, it encounters some limitations in video classification because of its underlying ontology derived from meta-information such as video tag and title. In this paper, we define recognized objects in a video and activity that is composed of video objects in a shot, and introduce a reasoning approach based on description logic. We define sequential rules for a sequence of shots in a video and describe how to classify it. For processing the large amount of increasing media data, we utilize Spark streaming, and a distributed in-memory big data processing framework, and describe how to classify media data in parallel. To evaluate the efficiency of the proposed approach, we conducted an experiment using a large amount of media ontology extracted from Youtube videos.

• Journal of KIISE
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• v.43 no.9
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• pp.963-973
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• 2016

Providing a semantic knowledge system using media ontologies requires not only conventional axiom reasoning but also knowledge extension based on various types of reasoning. In particular, spatio-temporal information can be used in a variety of artificial intelligence applications and the importance of spatio-temporal reasoning and expression is continuously increasing. In this paper, we append the LOD data related to the public address system to large-scale media ontologies in order to utilize spatial inference in reasoning. We propose an RDFS/Spatial inference system by utilizing distributed memory-based framework for reasoning about large-scale ontologies annotated with spatial information. In addition, we describe a distributed spatio-temporal SPARQL parallel query processing method designed for large scale ontology data annotated with spatio-temporal information. In order to evaluate the performance of our system, we conducted experiments using LUBM and BSBM data sets for ontology reasoning and query processing benchmark.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.347-355
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• 2008

In this paper single degree of freedom macro-element model was presented to investigate the interaction between soil and the deep foundation under the lateral loads. It was made by modelling each component related to the soil-structure interaction and combining them into one piece. It enhanced the conventional method that was not able to break down the interaction components in piece due to the usage of simple spring element for interaction. A proposed macro-element classified the stress components in relation to the interaction into frictional and compressive resistance. Each component was modelled using the classical plasticity theory, and finally combined in parallel. An example study was carried out using the proposed macro-element for deep foundation embedded in three layered cohesive soil. It showed improved results compared to the conventional method by producing additional information of the interaction components as well as the overall behavior of foundation.