• Journal of Information Technology Applications and Management
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• v.10 no.2
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• pp.19-31
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• 2003

We propose an indexing technique and an index selection algorithm for optimal OLAP query processing in object database systems, Although there are many research results on the relational database systems for OLAP Query processing, few researches have been done on the object database systems. Since OLAP queries represent complex business logic on a huge data ware-house, object database systems supporting the OLAP queries should have higher performance. Proposed bitmap index structure is an extension of conventional bitmap indexes for adapting object databases and provides higher performance with lower space overhead. We also propose a linear time solution of the index selection problem that will be used in the OLAP query optimization process.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.72-77
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• 2009

In this paper, performance of a turbo-coded PLC system is analyzed and simulated in a power line communication channel. Since the power line communication system typically operates in a hostile environment, turbo code has been employed to enhance reliability of transmitted data. The performance is evaluated in terms of bit error probability. As turbo decoding algorithms, Max-Log-MAP algorithms are chosen and performances are compared. The results in this paper can be applied to OFDM-based high-speed power line communication systems

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.605-606
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• 2008

The distance detection system receives stereo video input through 2 CCD cameras. Using a decoder, the image is changed to the YCbCr4:2:2 format and only the Y signal is saved in the 4*256*8bit shift register of the Dual-Port SRAM. As a result of the matching procedure, the Depth value, which is the distance information, is saved in SRAM, and the Depth Map is made and output to the TFT-LCD screen.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.100-106
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• 1992

In this pape, we designed and implemented a hardware accelerator for the generation of bit map font from Hangul outline font description for LBP (Laser Beam Printer) and screen applications Whole system was implemented as a double size PC/AT application board which consists of processing bolck and display block. The processing block has a master processor (MC68000)and two slave processors which are MC56001 and KAFOG chip responsible for the short vector generation. In the display block, TMS34061 was used for monitor display and GP425 was used for LBP print out. The resolution of the monitor is 640$\times$480 and that of LBP is 2385$\times$3390. The current system called KHGB90-B generates about 100 characters per second where each character consists of 32$\times$32 bits

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.213-216
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• 2001

In this paper, the performance of an OFDM/CDMA system with turbo coding is analyzed and simulated in a multipath fading channel. Bit error probability is derived fDr a Rayleigh fading channel. In an OFDM/CDMA system, an OFDM and a CDMA techniques are combined to exploit the advantages of both techniques. For decoding of turbo code, MAP decoding algorithm is employed. From the simulation results. it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding/decoding complexity. Also, it is shown that the BER performance is substantially improved by increasing the interleaver length for a fixed code rate and the increasing number of iterations used in the decoding process. The results in the paper can be applied to the design of OFDM-based CDMA system.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.63-66
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• 2005

분류란 여러 분야에서 쌓인 정보 데이터를 분석하여, 결과값에 대한 공통속성을 찾아내어 새로운 입력 데이터에 대해 보다 보편적인 결과를 분석하거나 예측하는 기법이다. 의사 결정 트리는 이러한 분류의 한 형태로 저장된 데이터를 활용하여 선험적 지식을 취득하고, 새로운 데이터에 대한 예측을 발생시키는 데이터 분석 방법이다. 그러나, 의사 결정 트리의 여러 가지 장점에도 불구하고 트리 구성에 많은 비용이 소요되는 단점이 존재한다. 점점 대량의 데이터를 다루어야 하는 현대 사회에서는 이러한 단점이 더욱더 커질 수 밖에 없다. 본 논문에서는 이러한 문제점을 해결하고자 비트맵을 활용한 의사 결정 트리의 구현을 제안한다. 비트맵을 사용하게 되면 의사 결정 트리 생성의 가장 큰 비용인 속성값 측정에서 높은 효율을 유지할 수 있게 된다. 또한 보다 효율적이고, 확장성이 높은 의사 결정 트리를 구현할 수가 있다.

• The KSFM Journal of Fluid Machinery
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• v.15 no.1
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• pp.52-57
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• 2012

Stall inception characteristics are researched to understand stall well. To realize different stall inception patterns, IGV stagger angle was changed. At design IGV stagger angle, spike, which is short length scale, is observed. Decreasing IGV stagger angle, spike changes to mode, which is long length scale, and further decreasing get multi cell. Compressor maps for each IGV stagger are shown to compare different stall inceptions. The characteristics of both spike and mode are confirmed in this experiment. Furthermore, transient from spike to mode is find. multi cell has 4cells and is little bit faster than mode. and multi cell shows 2nd, 3rd characteristics on compressor map.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.329-330
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• 2000

기가비트 속도를 지원하는 고속 라우터의 IP 주소 검색은 소프트웨어로 구현할 수 없다는 일부의 믿음과는 달리 소프트웨어만으로도 고속 IP 주소 검색의 구현이 가능하다. 기가비트 라우터의 IP 주소 검색은 최장 프로픽스일치 기법을 사용하여 라우팅 엔트리를 검색하는데, 56Gbps 속도를 지원하기위해서는 평균 513byte의 패킷을 800 nsec 이하의 속도로 처리하여야 한다. 본 논문에서는 범용 펜티엄 프로세서의 캐쉬 크기에 적합한 고속 라우팅을 위한 포워딩 테이블 구조를 제안하였으며, 400 MHz의 페티엄 II 프로세서를 이용한 실험에서 초당 수백만개의 IP 주소 검색을 실현하였다. 제안된 포워딩 테이블은 약 48,000여개의 실제 라우팅 엔트리에 대해 284Kbyte의 매우 작은 크기로 작성되었는데, 이 크기는 펜티엄 프로세서의 L2 케쉬에 저장될 수 있는 작은 크기이다. 제안된 포워딩 테이블을 이용한 평균 검색 시간은 라우팅 테이블 별로 320~530 nsec가 소요되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2372-2382
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• 1998

In this paper, we propose a new edge based finite state vector quantization method having better performance than conventional side-match finite state vector quantization. In our proposed scheme, each dCT transformed block is classified to 17 classes according to edge types. Each class has a different codebook based on its characteristis. Encoder classified each block to motion block or stationary block and constructed a merging map by using edge and motion information, and sent to decoder. We controled amoutn of bing bits transmitted with selecting modes accoridng to bandwidth of transmitting channel. Compared with conventional algorithms, H.263 and H.261 at low bit rate, our proposed algorithm shows better picture quality and good performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1403-1410
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• 1997

Because streaming mode connection server suitable to wide area ATM networks performs transmission, reception and lookup with time restriction for the transmission time of a cell, it has demerits of large cell loss incase that burst traffic occurs. Therefore, in this paper to decrease cell loss we propose a high speed CAM (Content Addressable Memory) which is capable of processing data of streaming mode connections server at a high speed. the proposed CAM is applied to forwarding table VPC map which performs function to output connection numbers about input VPI(Virtual Path Identifier)/VCI(Virtual Channel Identifier). The designed high speed CAM consist of DBL(Dual Bit Line) CAM structure performed independently write operation and match operation and two-port SRAM structure. Also, its simulation verification and full-custom layout is performed by Hspice and Composs tools in 0.8 .$\mu$m design rule.