• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.315-319
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• 2005

In this paper, we present a Petri Net (PN) model for reliability analysis of fault-tolerant database system models that consists of components one shared memory, bus, processors and database (disk). Each component can be failed and repaired individually. The system is operational as long as database and one of component is operational. We develop Stochastic Reward Net (SRN) Model for reliability analysis of database system. SRN is potential to define various reward functions. and can be easily used to obtain performance measures. The modeling techniques using variable cardinality, enabling function, timed transition priority in SRN are shown.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.12
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• pp.1815-1827
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• 1993

In this paper, we evaluate the performance of a Futurebus based multiprocessor system with MESI cache coherence protocol for four bus transaction types. Graphical symbols and compiler of SLAM II are used in modeling and simulation. A steady-state probability of each state for MESI protocol is computed by a Markov chain. The probability of each state is used as an input value for a correct simulation. Processor utilization, memory utilization, bus utilization, and the waiting time for bus arbitration are measured in terms of the number of processors, the hit ratio of cache memory, the probability of internal operation, and bus bandwidth.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.7
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• pp.708-712
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• 2008

Existing dynamic memory allocation schemes for general purpose operating system can not directly apply to the wireless sensor networks (WSNs). Because these schemes did not consider features of WSNs, they consume a lot of energy and waste the memory space caused by fragmentation. In this paper, we found features of WSNs applications and made the model which adapts these issues. Through this research, we suggest the slab allocator that reduces the execution time and the memory management space. Also, we evaluate the performance of our scheme by comparing to one of the previous systems.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.203-206
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• 2007

연속 전자 모델과 결합된 종래의 분자 동역학 방법은 원자 사이의 힘과 원자의 전기용량에 의해 야기되는 탄소 나노튜브의 구부러지는 성질의 특성을 해석하였다. 탄소 원자의 전기 용량은 탄소 원자의 길이에 따라 변하였다. 본 연구는 11.567nm($L_{CNT}$)의 길이와 $0.9{\sim}1.5nm(H)$의 안쪽 깊이를 가진 (5,5) 탄소 나노튜브 브리지로 MD 시뮬레이션을 수행하였다. 탄소 나노튜브는 금 표면에 부딪힌 후 탄소 나노튜브 브리지는 약 ${\sim}1{\AA}$의 크기로 금 표면에서 진동하며, 크기는 차츰 감소하였다. $H{\leq}1.3nm$일 때, 탄소 나노튜브 브리지는 첫 번째 충돌 후에 금 표면과 계속 접촉해 있었고, $H{\leq}1.4nm$일 때, 탄소 나노튜브 브리지는 몇 번의 충돌 후에 금 표면과 안정한 접촉상태가 되었다. $H/L_{CNT}$가 0.13보다 작을 때, 탄소 나노튜브 초소형 전자기기 메모리는 반영구적인 비활성의 메모리 장치가 되는 반면에 $H/L_{CNT}$가 0.14보다 클 때 탄소 나노튜브 초소형 전자기기 메모리는 휘발성이거나 스위치 장치로 동작할 수 있다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.1-7
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• 2010

In this paper, we use the maximum-likelihood detection by the estimation of trellis targets on the 16-level cell NAND flash memory. This mechanism has a performance gain by using a maximum-likelihood detector. The NAND flash memory channel is a memory channel because of the coupling effect. Thus, we use the known data arrays to finding the targets of trellis. The maximum-likelihood detection by proposed scheme performs better than the threshold detection on the 16-level cell NAND flash memory channel.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.661-665
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• 2006

모션 캡쳐 기반 컴퓨터 애니메이션 제작 기술은 컴퓨터 애니메이션 제작에 매우 광범위하게 사용되고 있다. 모션 캡쳐 기반 컴퓨터 애니메이션 제작 기술은 센서를 사용해서 대상체의 운동을 측정하여 운동 렌더링 파라미터를 추출한 후, 이 운동 파라미터를 컴퓨터에 옮겨서 그래픽 툴을 사용하여 애니메이션화 한다. 이러한 일련의 작업이 현재의 데스크 톱 컴퓨터에서는 문제없이 수행될 수 있지만, 모바일 임베디드 시스템에 그대로 적용되기에는 다소 무리가 있다. 왜냐하면, 모바일 임베디드 시스템의 경우, CPU의 계산 능력과 메모리의 크기가 매우 작기 때문에 이에 특화된 방법이 필요하게 된다. 이러한 취지에서 본 논문은 모바일 임베디드 시스템에서 메모리 사용 효율을 높이기 위해서, 추출된 운동 렌더링 파라미터의 데이터량을 줄여서 메모리에 저장하는 방안을 모색한다. 일반적으로 사용되는 영상 압축 기술은 복원 과정이 복잡해서 모바일 임베디드 시스템의 적은 계산력에 무리를 줄 수 있으므로, 가능한 복원 과정도 계산량이 적은 방안을 강구할 필요가 있다. 이와 같은 목적으로 본 논문에서는 추출된 운동 렌더링 파라미터의 프레임 별 변화를 시간 정합 함수로 모델링 하여, 정합 함수의 파라미터를 메모리에 저장하고, 정합 함수의 함수값 계산을 통해 운동 파라미터를 복원해 내는 쉽고 효율적인 방법을 제안한다. 그리고 본 정합 데이터 압축 방식을 사용하여 상용화된 모바일 임베디드 멀티미디어 시스템에서 효율적인 모션 캡쳐 기반 컴퓨터 애니메이션 제작을 시현한다.

• The Transactions of the Korea Information Processing Society
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• v.6 no.4
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• pp.1081-1089
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• 1999

Volume data modeling is concerned with finding a mathematical function which represents the relationship implied by the 3D data. Modeling a volume data geometrically can visualize a volume data using surface graphics without voxelization. It has many merits in that it is fast and requires little memory. We proposes, a method based on wavelet transformation and tetrahedrization. we implement a prototype system based on the proposed method. Last, we evaluated the proposed method comparing it with marching cube algorithm. the evaluation results show that though the proposed method uses only 13% of the volume data, the images generated is as good as the images generated by the marching cubes algorithm.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.80-90
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• 2010

In this paper, we introduce some issues to implement an agent system to support service mobility in home network environment, and describe detailed design method in terminal as well as server agent. Specifically, we describe user recognition module, signaling message receiving/parsing module of terminal agent and signaling message receiving/parsing module, multimedia switching module, memory management module of server agent. We define several parameters managed in IP sharing device and design binding table structure to support mobility. And we utilize M/M/1/K queueing theory to obtain relations between memory size, blocking probability and memory utilization. From the obtained results, we show that memory size can be predicted in server agent mounted on IP sharing device.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2C
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• pp.191-199
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• 2006

In this paper, we propose a method to implement a predistorter of the $rho$-th order inverse filter structure to prevent signal distortion and spectral re-growth due to the high PAPR (peak-to-average ratio) of the OFDM signals and the non-linearity of high-power amplifiers. We model the memory-less non-linearity of the high-power amplifier with a polynomial model and utilize the inverse of the model, the $rho$-th order inverse filter, for the predistorter. Once the non-linearity is modeled with a polynomial, since we can determine the $rho$-th order inverse filter only with the coefficients of the polynomial, large memory is not required. To update the coefficients of the non-linear high-power amplifier model, we can use LMS or RLS algorithms. The convergence speed is high since the number of coefficients is small, and the computation is simple since manipulation of complex numbers is not necessary.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.5
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• pp.498-509
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• 2001

Collaborative systems allow users, who may be far removed from each other geographically, to do collaborative work such as 3D animation, computer game, and industrial design in a single virtual space. This paper describes our experience to develop a collaborative system framework that aims at expanding the some functions of a stand-alone visual modeling tool, called 3D Studio Max, into those of the distributed collaborative working environments. The paper mainly deals with design and implementation of a 3D shared-object Plug-In with respect to the 3D Studio Max Plug-In Software Development Kit in the distributed collaborative system developed by the authors. There are two major functions of the proposed scheme; one is to write 3D object-information to the shared memory after extracting it from the 3D Studio Max, the other is to create 3D objects after retrieving them from the shared memory. Also, the proposed scheme provides a simple way of storing 3D objects that have variable size, by means of shared memory which located in between the collaborative system clients and 3D studio Max. One of the remarkable virtures of the Plug-In is to reduce a considerable amount of shared object data which in consequence can mitigate the network overhead. This can be achieved by the fact that the system is able to extract a minimum amount of 3D objects that are required to transmit. Also, using the proposed scheme, user can facilitate 3D Studio Max into distributed collaborative working environments. This, in consequence give many benefits such as saving time as well as eliminating space constraints in the course of 3D modeling when we are under industrial design process.