• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10A
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• pp.775-779
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• 2003

A spatio-temporal searcher structure for 3rd generation W-CDMA systems is proposed to enhance the detection capability of the multi-path searcher for the desired signal. This searcher employs the spatio-temporal signal structure to search for newly emerging multipath signals. The proposed multi-path searcher provides better detection capability andthus reduces the mean acquisition time. The detection and false alarm probabilities of new and conventional schemes are calculated and numerical examples of mean acquisition time are given thereafter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1022-1027
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• 1999

This paper proposes method that uses Time-Difference-of-Arrival(TDOA) of Forward Pilot signals from base stations(BS) arriving at a mobile station(MS) as a position location method of CDMA MS. MS searcher does acquisition of BS Pilot signals and measurement of TDOAs. In order to do it, its processing gain is very important. Proportional relationship of the gain to the signal coherent integration interval is theoretically derived and analyzed and field test is performed to show acquisition of weak Pilot signals and stable measurements of TDOA values by increasing the gain. Also, signal strength decrease exponentially by the distance it travels. Therefore, improvement of the searcher gain makes possible to acquire Pilot signals at a location far away from BS. Variation of possible position estimation area relative to the signal strength within a cell is simulated with computer. Neglecting shadow effect it indicated necessity of detecting signals below -35dB in order to cover over 90% of cell area. Thus, efforts to maximize searcher coherent integration interval in order to acquire weak Pilot signals are required for expansion of position estimation area and measurement of stable TDOA values.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.8
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• pp.37-44
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• 1997

We implemented a code searcher which is used for the PN(pseudo noise) code acquisition in CDMA cellular mobile station. To reduce the reuired hardware and the code acquisition time, we used the double dwell structure which is an effective serial code acquisition metho. We designed a code acquisition has acquired within 1/2 PN chip range. The code searcher is implemented using 0.8 micron code searcher is successfully working in CDMA cellular mobile station and it satisfies the code acquisition time specified in IS-95 standard.

• ETRI Journal
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• v.30 no.4
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• pp.495-505
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• 2008

This paper presents a parallel processing searcher structure for the initial synchronization of a direct sequence ultra-wideband (DS-UWB) system, which is suitable for the digital implementation of baseband functionalities with a 1.32 Gsample/s chip rate analog-to-digital converter. An initial timing acquisition algorithm and a data demodulation method are also studied. The proposed searcher effectively acquires initial symbol and frame timing during the preamble transmission period. A hardware efficient receiver structure using 24 parallel digital correlators for binary phase-shift keying DS-UWB transmission is presented. The proposed correlator structure operating at 55 MHz is shared for correlation operations in a searcher, a channel estimator, and the demodulator of a RAKE receiver. We also present a pseudo-random noise sequence generated with a primitive polynomial, $1+x^2+x^5$, for packet detection, automatic gain control, and initial timing acquisition. Simulation results show that the performance of the proposed parallel processing searcher employing the presented pseudo-random noise sequence outperforms that employing a preamble sequence in the IEEE 802.15.3a DS-UWB proposal.

• Journal of the Korean Society for Library and Information Science
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• v.48 no.2
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• pp.379-398
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• 2014

This pilot study explored the effect of mental demand on a Web searcher's thoughts, emotions, efforts, and performance in Web searches in order to address whether or not there is any difference between searchers exposed to mental demand manipulation and searchers not exposed. Research data were collected via think-aloud protocol (TAP) with a dual-task in experiments and interviews with 10 subjects who participated in this study. For the searcher's thoughts, relevance judgment was found to be hindered by mental demand. For the searcher's emotions, the experimental group was more frustrated than the control group. With respect to the searcher's efforts, searchers for the experimental group with mental demand manipulation were more likely to spend more time, make fewer queries, and visit fewer pages but work harder to find more relevant information that they needed. Lastly, with regard to the searcher's performance, it is likely that performance was highly dependent upon the completion of the search tasks for both groups. The NASA-TLX six components and cognitive load scores of searchers did not make a significant difference in the outcome. The findings support the use of a dual-task methodology as a promising approach for the assessment of cognitive load induced by complex Web searches.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.69-72
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• 2000

In CDMA systems, the performance of the typical multipath searcher degrades much according as the signal to noise ratio becomes low. In this paper, multipath searcher algorithm is proposed based on sliding window to overcome this drawback. In searcher systems, correlation values between incoming and local PN sequences are used to acquire multipath components. Therefore more accurate distributions of correlation values obtained through this proposed algorithm enables to get higher detection probability. In computer simulations, it is verified that proposed algorithm has better performances in Rayleigh fading channel and Gaussian channel.

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.41-47
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• 2016

This paper considers simple polygon search problem. How many searchers find a mobile intruder that is arbitrarily faster than the searcher within polygon art gallery? This paper uses the visibility graph that is connected with edges for mutually visible vertices. Given visibility graph, we select vertex u that is conjunction ${\Delta}(G)$ in $N_G(v)$ for $d_G(v){\leq}4$. We decide 1-searchable if $1{\leq}{\mid}u{\mid}{\leq}2$ and 2-searchable if ${\mid}u{\mid}{\geq}3$. We also present searcher's shortest path. This algorithm is verified by varies 1 or 2-searchable polygons.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.10
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• pp.39-46
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• 1999

In this paper, we propose new hardware architecture of a fast searcher for an initial code acquisition in wideband CDMA wireless local loop systems. The proposed searcher uses double-dwell serial search algorithm and has N active correlators for the high performance code acquisition. Since the N active correlators are designed with pipelined architecture, it is possible to reduce the hardware complexity with only one energy calculation. Our architecture is designed using VHDL to meet wideband CDMA wireless local loop standard and verified under JTC wideband channels. Average code acquisition time of the proposed fast searcher which has 16 correlators is about 40 seconds in case of initial installation and 0.16 seconds when a base station is known. The verified fast searcher is synthesized with in $0.6\mu\textrm{m}$ LG library. The synthesized searcher has 15.8K rates when the number of 4he correlators is 16.

• The Journal of Information Systems
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• v.12 no.2
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• pp.151-163
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• 2003

This research studied E-Biz strategy based on the types of internet shopping-mall and user group. This study classified types of internet user into suffer group, searcher group, and confusion group according to navigation characteristics. The types of internet shopping-mall were divided into total directed mall, total mediated mall, special directed mall, and special mediated mall. The empirical study revealed that the intention of purchase has positive relationship with the assurance of e-SERVQUAL. Mediated type shopping-mall had higher market share than directed type in the use of internet shopping-mall. Suffer group was the target market of total mediated shopping-mall. Users of this group considered importantly the trust of e-SERVQUAL. Searcher group targeted special mediated shopping-mall. They had significant consideration to the responsiveness of e-SERVQUAL. Confusion group targeted direct shopping-mall. These groups had important consideration to the assurance of e-SERVQUAL.

• Journal of Satellite, Information and Communications
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• v.2 no.1
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• pp.1-6
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• 2007

In this paper, we proposed new algorithm that improves the acquisition performance of the PN code searcher used in DS-CDMA systems. Using the mean deviation computed from the correlator output of the PN code searcher, it is possible to estimate received channel environment. To satisfy the required acquisition performance in estimated channel environment, the PN code searcher changes the correlator tap size adaptively. Proposed algorithm shows improved performance compared with conventional algorithm using the fixed correlator tap size.