• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04a
• /
• pp.397-399
• /
• 2002

영상압축 인코더에서 가장 많은 계산량을 차지하는 부분이 움직임 벡터를 추정하는 부분이다. 일반적인 3단계 탐색 (Three-Step Search: TSS) 방법은 한 개의 매크로 블록에 대해 25개의 탐색점에 대해서 탐색을 한다. 본 논문에서는 주변 움직임 벡터로부터 예측된 움직임 벡터를 또 하나의 탐색 점으로 추가하는 수정된 3 단계 탐색 방법을 제안한다. 제안한 방법은 기존 방법 보다 일반적으로 속도를 향상시키면서 최대 15% 정도 비트율을 감소시킬 수 있다.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.7
• /
• pp.12-18
• /
• 2017

This paper presents a Dijkstra's-search-based sphere decoding (SD) algorithm with limited complexity for the symbol detection in MIMO communication systems. The Dijkstra search-based SD is efficient to achieve a near-optimal error rate in the MIMO symbol detection, but has a critical problem in that its complexity is variable and can correspond to that of the exhaustive search in the worst case. The proposed algorithm limits the computations while achieving a near-optimal error rate. Simulation results show that the error rate is near optimal even with the limited complexity.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.1
• /
• pp.107-109
• /
• 2016

In this paper, we address the TCP-over-WLAN performance problem that occurs during periodic active background scanning with which mobile devices discover available APs in the vicinity. We measure the impact of the scanning period on the TCP throughput and observe a significant performance degradation when the scan operation period is shortened. Our experimental analysis has identified the main cause of the problem, that is, the associated AP continues to send packets to the mobile device even when the device is not able to receive due to the scanning operation.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.37 no.2
• /
• pp.28-38
• /
• 2000

This paper proposes a fractal compression method using the domain classification and local searching, which utilize DCT coefficient characteristic Generally, the fractal Image encoding method has a time consuming process to search a domain to be matched with range block In order to reduce computation complexity, the domain and range regions are respectively classified into 4 category by using the characteristics of DCT coefficients and each range region is encoded by a method suitable for the property of its category Since the bit amount of the compressed image depends on the number of range blocks, the matching of domain block and range block is induced on the large range block by using local search, so that compression ratio is increased by reducing the number of range block In the local search, the searching complexity is reduced by determining the direction and distance of searching using the characteristics of DCT coefficients The experimental results shows that the proposed algorithm have 1 dB higher PSNR and 0 806 higher compression ratio than previous algorithm.

• Journal of the Korean Society for information Management
• /
• v.12 no.1
• /
• pp.143-161
• /
• 1995

This paper defines online search strategy as a global approach to the resolution of online searching. Five search strategy models including Brief Search. Building Blocks Strategies. Successive Facet Strategies, Successive Fractions Approach, and Citation Pearl Growing, are critically reviewed. Applicability and adaptability of each strategy are examined in the real concrete online searching environment.

• Proceedings of the Korean Society for Information Management Conference
• /
• 1994.12a
• /
• pp.3-6
• /
• 1994

본 연구에서는 전문데이터베이스의 자연어 검색에 있어서 탐색시소러스의 검색효율과 퍼지시소러스 관련어 확장검색의 검색효율을 측정하였다. 한국경제신문사 ECONET의 기사 데이터베이스를 대상으로 질문의 기본 탐색어를 계층어와 관련어로 확장검색한 결과 탐색시소러스를 이용한 관련어 확장검색과 종합검색이 정확률은 저하시키지 앓고 재현율을 향상시켰다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.8
• /
• pp.701-709
• /
• 1991

In this paper, an analysis approach for the performance of serial search burst format direct sequence spread spectrum[DS-SS] code aequision system using matched filter is persented. And an acquisition system using digital matched filter is chosen for the analysis by this approach. In this acqusition system, since chip decision should be performaned before matched filter

• Journal of the Korean Society for Library and Information Science
• /
• v.32 no.4
• /
• pp.209-225
• /
• 1998

This research focuses on how users behave when they search by subject using online public access catalog(OPAC). Major findings are as follows. 1)Main access poults are subject field$(55.2\%)$and title field$(42.2\%)$. 2) The search failure rate in subject searching is $59.3\%$. 3) Ma]or reasons for subject search failures are two-fold : use of inappropriate search terms $(48.5\%)$ and non-use of Boolean Operators$(42.5\%)$. 4) In order to overcome search failures users tend to change originally used search terms$(42.0\%)$ and search fields$(33.8\%) into different ones.

• Proceedings of the Korea Technology Innovation Society Conference
• /
• 2016.05a
• /
• pp.239-247
• /
• 2016

• Journal of the Korean Society for Library and Information Science
• /
• v.31 no.2
• /
• pp.177-197
• /
• 1997

The study measured whether two search engines retrieve different Web documents for 6 queries. Two different search engines, Alta Vista in terms of keyword search engines and Yahoo in terms of subject directory engines were measured using as criteria, total number of documents retrieved, total number of relevant documents retrieved, recall and precision ratios. In addition, Alta Vista was suitable for specific and technical terms, while Yahoo was effective for general and plain terms. However, more elaborate research needs to be tested in terms of query characteristics.