• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1133-1143
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• 2005

In this paper, we propose an enhanced two-step search scheme for rapid and reliable signal acquisition in UWB systems under multipath channels. The proposed TSS-LS (Two-Step Search scheme with the Linear search based Second step) achieves rapid acquisition performance comparable to the conventional TSS-BS (Two-Step Search scheme with the Bit reversal search based Second step) already proposed by the authors, based on the single-dwell search with two-step thresholds and search windows. However, unlike the TSS-BS which employs the bit reversal search in the second step, the proposed TSS-LS utilizes the linear search in the second step to improve the reliability of signal acquisition. Simulation results with multipath channel models by IEEE 802.15.3a show that the two-step search schemes for the UWB signal acquisition can achieve sig nificant reduction of the required mean acquisition time as compared to general search schemes. In addition, we observe that the proposed TSS-LS achieves quite good bit error rate performance for large signal-to-noise ratios, which is favorably comparable to the case of ideal perfect timing.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.285-288
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• 2005

In this paper, we propose a two step Binary Exponential search algorithm for rapid acquisition time of UWB(Ultra Wide Band) signal on UWB communication systems. Previous proposed timing acquisition algorithm is searching whole frame that consist of the number of n Bins to terminate search, however this paper proposed two step Binary Exponential search algorithm can achieve remarkable reduction of UWB signal acquisition time as limiting search group. Proposed search algorithm is consisting of search group establishment step and Bit Reversing of search group establishment step.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8C
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• pp.742-753
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• 2005

In this paper, we propose a rapid and reliable signal acquisition scheme for UWB (Ultra Wide Band) systems in typical indoor wireless channels. The proposed scheme is a two-step search with different thresholds and search window applied to a single correlator, where each step utilizes the single-dwell search with the bit reversal. Simulation results in IEEE 802. I5 Task Group .3a UWB indoor wireless channel show that the proposed scheme for the LHWB signals can achieve significant reduction of the required mean acquisition time as compared to the conventional single-dwell bit reversal search and double-dwell bit reversal search with more complex structure employing two correlators for various threshold levels. In addition, it is also observed that the proposed scheme can achieve much faster and reliable signal acquisition in noisy environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.331-340
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• 2006

In this Paper, we propose to extend the TSS-LS(Two-Step Search scheme with Linear search based Second step) scheme which was already proposed by the authors for coherent UWB(Ultra Wide Band) systems, to rapid and reliable acquisition of noncoherent UWB systems in multipath channels. The proposed noncoherent TSS-LS employing simple energy window banks utilizes two different thresholds and search windows to achieve fast acquisition. Furthermore, the linear search is adopted for the second step in the proposed scheme to correctly find the starting point in the range of effective delay spread of the multipath channels, and to obtain reliable BER(Bit Error Rate) performance of the noncoherent UWB systems. Simulation results with multipath channel models by IEEE 802.15.3a show that the proposed two-step search scheme can achieve significant reduction of the required mean acquisition time as compared to general search schemes. ]n addition, the proposed scheme achieves quite good BER performance for large signal-to-noise ratios, which is favorably comparable to the case of ideal perfect timing.

• Journal of Advanced Navigation Technology
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• v.12 no.2
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• pp.146-153
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• 2008

Due to the extremely short pulse in the Ultra-Wideband (UWB) technology, the accurate synchronization acquisition method is very important for both high data-rate WPAN and low data-rate WPAN. In this paper, we propose the synchronization acquisition algorithm based on two-step signal search method to acquire the synchronization in the UWB multi-path channel. At the first step, the search window is divided by two and the window that has higher power is chosen as a next search window. This operation is repeated until the measure power of the search window is smaller than the threshold value. At the second step, we employ Linear Search algorithm to the search window obtained at the first step for fine search. The proposed algorithm is proved that the synchronization acquisition is faster than the parallel search algorithm and it shows good performance in environment of the SNR extreme changes by the simulation.

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.424-432
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• 2020

The present study aimed to analyze the metaproteome of the microbial community comprising harmful algal bloom (HAB) in the Daechung reservoir, Korea. HAB samples located at GPS coordinates of 36°29'N latitude and 127°28'E longitude were harvested in October 2013. Microscopic observation of the HAB samples revealed red signals that were presumably caused by the autofluorescence of chlorophyll and phycocyanin in viable cyanobacteria. Metaproteomic analysis was performed by a gelbased shotgun proteomic method. Protein identification was conducted through a two-step analysis including a forward search strategy (FSS) (random search with the National Center for Biotechnology Information (NCBI), Cyanobase, and Phytozome), and a subsequent reverse search strategy (RSS) (additional Cyanobase search with a decoy database). The total number of proteins identified by the two-step analysis (FSS and RSS) was 1.8-fold higher than that by one-step analysis (FSS only). A total of 194 proteins were assigned to 12 cyanobacterial species (99 mol%) and one green algae species (1 mol%). Among the species identified, the toxic microcystin-producing Microcystis aeruginosa NIES-843 (62.3%) species was the most dominant. The largest functional category was proteins belonging to the energy category (39%), followed by metabolism (15%), and translation (12%). This study will be a good reference for monitoring ecological variations at the meta-protein level of aquatic microalgae for understanding HAB.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.809-824
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• 2002

we propose two methods which separate the variable selection step and the split-point selection step. We call these two algorithms as CHITES method and F&CHITES method. They adapted some of the best characteristics of CART, CHAID, and QUEST. In the first step the variable, which is most significant to predict the target class values, is selected. In the second step, the exhaustive search method is applied to find the splitting point based on the selected variable in the first step. We compared the proposed methods, CART, and QUEST in terms of variable selection bias and power, error rates, and training times. The proposed methods are not only unbiased in the null case, but also powerful for selecting correct variables in non-null cases.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.141-146
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• 2005

In this paper, we propose to extend the TSS-LS (Two-Step Search scheme with Linear search based Second step) scheme which was already proposed by the authors for coherent UWB (Ultra Wide Band) systems, to rapid and reliable acquisition of noncoherent UWB systems in multipath channels. The proposed noncoherent TSS-LS employing simple energy window banks utilizes two different thresholds and search windows to achieve fast acquisition. Furthermore, the linear search is adopted for the second step in the proposed scheme to correctly find the starting point in the range of effective delay spread of the multipath channels, and to obtain reliable BER (Bit Error Rate) performance of the noncoherent UWB systems. Simulation results show that the proposed TSS-LS can achieve significant reduction of the required mean acquisition time as compared to general search schemes. In addition, the proposed scheme achieves quite good BER performance, which is favorably comparable to the case of ideal perfect timing.

• 한국정보교육학회:학술대회논문집
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• 2010.08a
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• pp.227-233
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• 2010

Graph is applied to GIS, Network, AI and so on. We use graph concept in our daily life unconsciously. So this paper describe how graph concept is used when robot searches shortest path between two distinct vertices. It is performed in real world. For this, it consists of three step; maze traverse, graph generation, and shortest path search. Maze traverse steps is that robot navigates maze. It is most difficult step. Graph generation step is to represent structural information into graph. Shortest path search step is to that robot move between two vertices. It is not implemented yet. So we introduce process in design level.

• The Journal of Information Systems
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• v.26 no.3
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• pp.171-185
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• 2017

Purpose Recently, there has been an increase in attempts to analyze social phenomena, consumption trends, and consumption behavior through a vast amount of customer data such as web search traffic information and social buzz information in various fields such as flu prediction and real estate price prediction. Internet portal service providers such as google and naver are disclosing web search traffic information of online users as services such as google trends and naver trends. Academic and industry are paying attention to research on information search behavior and utilization of online users based on the web search traffic information. Although there are many studies predicting social phenomena, consumption trends, political polls, etc. based on web search traffic information, it is hard to find the research to explain and predict tourism demand and establish tourism policy using it. In this study, we try to use web search traffic information to explain the tourism demand for major cities in Gangwon-do, the representative tourist area in Korea, and to develop a nowcasting model for the demand. Design/methodology/approach In the first step, the literature review on travel demand and web search traffic was conducted in parallel in two directions. In the second stage, we conducted a qualitative research to confirm the information retrieval behavior of the traveler. In the next step, we extracted the representative tourist cities of Gangwon-do and confirmed which keywords were used for the search. In the fourth step, we collected tourist demand data to be used as a dependent variable and collected web search traffic information of each keyword to be used as an independent variable. In the fifth step, we set up a time series benchmark model, and added the web search traffic information to this model to confirm whether the prediction model improved. In the last stage, we analyze the prediction models that are finally selected as optimal and confirm whether the influence of the keywords on the prediction of travel demand. Findings This study has developed a tourism demand forecasting model of Gangwon-do, a representative tourist destination in Korea, by expanding and applying web search traffic information to tourism demand forecasting. We compared the existing time series model with the benchmarking model and confirmed the superiority of the proposed model. In addition, this study also confirms that web search traffic information has a positive correlation with travel demand and precedes it by one or two months, thereby asserting its suitability as a prediction model. Furthermore, by deriving search keywords that have a significant effect on tourism demand forecast for each city, representative characteristics of each region can be selected.