• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.12A
• /
• pp.1852-1860
• /
• 2000

본 논문은 IS-95를 기반으로 하는 CDMA(Code Division Multiple Access) 탐색자의 저전력 설계방법에 대하여 기술하였다. 탐색자는 역확산, 동기 누적단, 에너지 계산단, 2개의 비교단과 비동기 누적단으로 구성되어 있다. 제안된 방법은 Rescheduling과 Strength Reduction을 이용한 방법, Precomputation을 이용한 방법, 그리고, Synchronous 누적기를 이용한 세 가지 방법이다. VHDL을 이용하여 설계되었고, SYNOPSYSTEM에서 시뮬레이션을 수행하여 그 기능을 검증하였고, 합성하였다. 또한 SYNOPSYSTEM의 Design Power를 사용하여 소모 전력을 측정하였다. 측정결과 기존의 설계방법과 비교해서 최대 67%의 전력 감쇠와 41%의 면적 감소 효과를 얻었다.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2024.01a
• /
• pp.313-315
• /
• 2024

본 논문에서는 이미지 검색기를 통한 랜드마크 인식 방법을 제안한다. 특정 랜드마크 데이터세트에서 라벨링을 하지 않은 비지도 학습을 통해서 이미지에서 랜드마크의 클래스 분류를 위한 특징을 추출한다. 학습된 모델을 랜드마크 데이터세트인 Paris6k 데이터세트와 Oxford5k 데이터세트에 적용하여 랜드마크 인식 정확도를 확인하였다. 성능과 속도를 강화하기 위해 이미지 특징 추출 모델로 ResNet 대신에 YOLO에서 사용된 CSPDarknet-53을 사용하여 모델의 크기를 줄이고 랜드마크 인식 정확도를 높였다. 그리고 모델로부터 추출된 특징의 수를 줄여 이미지 검색 시 소요되는 시간을 감소시켰다. 학습된 모델로 rOxford5k 데이터 세트에 적용 시 mAP 80.37, rParis6k에서 mAP 89.07을 얻었다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.9A
• /
• pp.656-663
• /
• 2009

In 3GPP LTE system downlink, PSS (primary synchronization signal) and SSS (secondary synchronization signal) sequences are used for initial cell search and synchronization. UE (user equipment) detects slot timing, frequency offset, and cell ID by using PSS. After that it should detect frame timing, cell group ID, and CP length by using SSS. But in 3GPP LTE, there are two kinds of CP length, so we should operate FFT twice. In this paper, to minimize SSS detection complexity in cell searcher, we propose a CP length pre-decision algorithm that reduces the arithmetical complexity by half at most, with negligible performance degradation.

• Journal of KIISE:Computing Practices and Letters
• /
• v.9 no.1
• /
• pp.60-69
• /
• 2003

In an Information Retrieval System(IRS) based on an inverted file as a file structure it is possible to retrieve related documents when the searcher know the complete words of searching fields. however, there are many cases in which the searcher may not know the complete words but a partial string of words with which to search. In this case, if the searcher can search indexes that include the known partial string, it is possible to retrieve related documents. Futhermore, when the retrieved documents are few, we need a method to find all documents having indexes which include known the partial string. To satisfy these requests, the searcher should be able to construct a query formulation that uses the term truncation method. Also the IRS should have an electronic dictionary that can support a truncated search term. This paper designs and implements an electronic dictionary(ED) structure to support a truncation search efficiently. The ED guarantees very fast and constant searching time for searching a term entry and the inversely alphabetized entry of it, regardless of the number of inserted words. In order to support a truncation search efficiently, we use the Trie structure and in order to accommodate fast searching time we use a method using array. In the searching process of a truncated term, we can reduce the searching time by minimizing the length of string to be expanded.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.2
• /
• pp.117-125
• /
• 2003

In this paper, we propose a new code acquisition architecture having the features of low complexity and high speed for the MC-CDMA system. The newly designed searching finger has function of the searcher as well as the finger. The searching finger tests the PN code Phase as the searcher during the initial acquisition, and as the finger after the initial acquisition. The proposed system has reduced the average acquisition time of the PN codes to $T_{acq}$/19 in the 20MHz MC-CDMA system with 75% reduction of H/W complexity.y.

• Journal of Korean Library and Information Science Society
• /
• v.40 no.4
• /
• pp.139-158
• /
• 2009

This paper used the network analysis method to analyse a variety of attributes of searcher's search behaviors which was appeared on search access log data. The results of this research are as follows. First, the structure of network represented depending on the similarity of the query that user had inputed. Second, we can find out the particular searchers who occupied in the central position in the network. Third, it showed that some query were shared with ego-searcher and alter searchers. Fourth, the total number of searchers can be divided into some sub-groups through the clustering analysis. The study reveals a new recommendation algorithm of associated searchers and search query through the social network analysis, and it will be capable of utilization.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.7 no.1
• /
• pp.231-246
• /
• 1994

A major problem for information retrieval research in the past three decades has been methodology, even though some progress has been made in obtaining useful results from methodologically sound experiments. Within a methodology, potential problems include artificial data generated by the researcher, small sample size interpretation of findings. Critics have pointed out that some room exists for improving methodology of information retrieval research; using existing data, having big enough sample size, including large numbers of search queries, introducing more control in relation to variables, utilizing more appropriate performance measures, conducting rests carefully and evaluating findings properly. Relevance judgments depend entirely on the perception of the user and on the situation of the moment. In an experiment, the best judge of relevance is a user with a well defined information need. Normally more than two categories for relevance judgments are desirable becase there are degrees of relevance. In experimental design, careful control of variables is meeded for internal validity. When no single database exists for comparison, existing operational databases should be used cautiously, Careful control for the variations of search queries, inter-searcher sonsistency, intra-searcher consistency and search strategies is necessary. Parametric statistics requiring rigid assumptions are not appropriate in information retrieval research and non-parametric statistics requiring few assumptions are necessary. Particularly, the sign test and the Wilcoxon test are good alternatives.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.10a
• /
• pp.13-16
• /
• 2004

This paper deals with a one-searcher multi-target search problem where targets with different detection priorities move in Markov processes in each discrete time over a given space search area, and the total number of search time intervals is fixed. A limited search resource is available in each search time interval and an exponential detection function is assumed. The searcher can obtain a target detection award, if detected, which represents the detection priority of target and is non-increasing with time. The objective is to establish the optimal search plan which allocates the search resource effort over the search areas in each time interval in order to maximize the total detection award. In the analysis, the given problem is decomposed into intervalwise individual search problems each being treated as a single stationary target problem for each time interval. An associated iterative procedure is derived to solve a sequence of stationary target problems. The computational results show that the proposed algorithm guarantees optimality.

• The Magazine of the IEIE
• /
• v.29 no.4
• /
• pp.62-76
• /
• 2002

스마트 안테나는 한정된 채널을 최대한 효율적으로 이용하여 용량(capacity)을 최대화시킬 수 있는 기술이다. 본 논문은 스마트 안테나의 원리와 기술을 설명하고 한양대학교 통신신호처리 연구실에서 연구·개발 중인 동기식 CDMA 스마트 안테나 시스템을 사용하여 이동통신 시스템의 주된 관심사인 용량을 최대화하는 방법을 제시한다. 스마트 안테나 시스템의 전체적인 성능 증가를 위해서는 핑거(finger)뿐 아니라 탐색기(searcher), 추적기(tracker) 각각의 성능도 우수해야 하므로, 본 논문에서는 현재까지 활발히 연구가 이루어지지 않은 탐색기, 추적기의 성능을 분석하고 BER(Bit Error Rate), FER(Frame Error Rate) 및 검출 확률 (detection probability)등의 모의 실험 결과를 바탕으로 스마트 안테나의 우수성을 분석한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.5
• /
• pp.493-502
• /
• 2009

In this paper, we compare the performance of initial timing acquisition in direct sequence ultra-wideband(DS-UWB) systems with different transmit pulse shaping filters through extensive computer simulations. Simulation results show that the timing acquisition performance of the DS-UWB system, whose chip rate is 1.32 Gchip/s, employing a rectangular transmit filter is similar to that employing a square root raised cosine(SRRC) filter with an interpolation factor of 4 in the realistic UWB channels(CM1 and CM3) as well as the additive white Gaussian noise(AWGN) channel. Additionally, we present both a 24-parallel digital correlator structure and a 24-parallel processing searcher operating at a 55 MHz system clock, and then briefly discuss the initial timing acquisition procedure. Because we can adopt an 1.32 Gsample/s digital-to-analog(D/A) converter and an 1.32 Gsample/s analog-to-digital(AID) converter in the DS-UWB system by employing the rectangular transmit filter, we have a realistic solution for the DS-UWB chipset development.