• Title/Summary/Keyword: second-order statistics

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A Qualitative Research about the Purchase Behavior of Internet Shoppers (인터넷 쇼핑몰 이용자의 구매행동에 관한 질적연구)

  • 고은주;김성은
    • Journal of the Korean Home Economics Association
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    • v.42 no.1
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    • pp.153-166
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    • 2004
  • The purpose of this study was to examine the internet shoppers' new purchase behavior, to examine the general purchase behavior(i.e., purchase pattern, preference), and to examine the related factors to promotion strategies(i.e., e-mail, event) of internet shopping mall. Focus group interviews were done with 40 internet shopping-mall users on May, 2003 for the data collection. Data were analyzed by content analysis and descriptive statistics(i.e., frequency, percent). The results of this study were as following. First, competitive price, accurate product and service information and convenience were considered as important factors in the new purchase behavior among internet shoppers. Second, the more frequent purchasing time through the internet shopping mall were on weekdays rather than weeekends and the most preferred information search engine were category type, item type, and price type in order. Third, e-mails from internet shopping mall were most likely opened by internet shoppers, that is to say, e-mail can be the efficient communication tool as well as the possible promotion strategies. Specifically, the title of email was considered as an important factor to approach the target consumers.

Blind Multi-user Estimation for Asynchronous DS-CDMA Systems (비동기 DS-CDMA 시스템에서의 블라인드 다중사용자 채널 추정 기법)

  • 정형성;성하종;이충용;유대희
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.7A
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    • pp.939-946
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    • 1999
  • A new blind multi-user channel estimation algorithm for the mobile communication systems is proposed. The proposed algorithm exploits the second-order statistics of a received signal and the subspace concept, and requires much less computational complexity than the existing algorithms. The algorithm can reduce the comptational load by estimating the physical channels excluding the spreading codes. We formulate the algorithm using the multi-channel model for asynchronous DS-CDMA systems and perform numerical experiments to evaluate the performance of the proposed algorithm.

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Maximum Likelihood and Signal-Selective TDOA Estimation for Noncircular Signals

  • Wen, Fei;Wan, Qun
    • Journal of Communications and Networks
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    • v.15 no.3
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    • pp.245-251
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    • 2013
  • This paper addresses the issue of time-difference-of-arrival (TDOA) estimation for complex noncircular signals. First, under the wide-sense stationary assumption, we derive the maximum likelihood (ML) estimator and the Cramer-Rao lower bound for Gaussian noncircular signals in Gaussian circular noise. The ML estimator uses the second-order statistics information of a noncircular signal more comprehensively when compared with the cross-correlation (CC) and the conjugate CC estimators. Further, we present a scheme to modify the traditional signal-selective TDOA methods for noncircular signals on the basis of the cyclostationarity of man-made signals. This scheme simultaneously exploits the information contained in both the cyclic cross-correlation (CCC) and the conjugate CCC of a noncircular signal.

Second-Order Statistics of System with Microdiversity and Macrodiversity Reception in Gamma-Shadowed Rician Fading Channels

  • Bandjur, Milos;Sekulovic, Nikola;Stefanovic, Mihajlo;Golubovic, Aleksandra;Spalevic, Petar;Milic, Dejan
    • ETRI Journal
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    • v.35 no.4
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    • pp.722-725
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    • 2013
  • In this letter, a wireless communication system with microdiversity and macrodiversity reception in gamma-shadowed Rician fading channels is considered. Exact and rapidly converging infinite-series expressions for the average level crossing rate and average fade duration at the output of the system are provided. Numerical results are presented graphically to illustrate the proposed mathematical analysis and to examine the effects of the system's parameters on the quantities considered.

Error-robust experimental designs: D- and heteroscedastic G-optimalities (D-와 이분산 G-최적을 중심으로 한 오차로버스트 실험계획법)

  • 김영일
    • The Korean Journal of Applied Statistics
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    • v.6 no.2
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    • pp.303-309
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    • 1993
  • In this paper we have defined two approaches to be error-robust when the precise form of error-structure is unknown. An experiment is optimal by the first criterion if it maximizes the minimum effciency over all candidates of error structure and is optimal by the second if it maximizes the minimum average of the efficiency over all candidates of error structure. In order to appreciate the basic implications of each design criterion, these approaches are applied to two different experimental situations, D- and heteroscedastic G-optimalities.

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Evaluating the Causal Relationships among Organizational Support, Organizational Commitment, Job Satisfaction, and Service Quality in the Hotel F & B Department (호텔 식음료부서에서 조직지원, 조직몰입, 직무만족과 서비스품질의 인과관계 평가)

  • 강종헌
    • Korean journal of food and cookery science
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    • v.19 no.2
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    • pp.155-164
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    • 2003
  • The purpose of this study was to examine, in a service context, construct validity and generalizability of widely used and accepted measures of perceived organizational support, job satisfaction, organizational commitment, and service duality, and to test each measures' predictive utility in this context with path analysis. Of 350 subjects, 309 subjects participated in the analysis. Descriptive statistics (frequencies), exploratory factor analysis, reliability analysis, zero-order partial correlation analysis, and confirmatory factor analysis were used for this study. The findings from this study are as follows. First, perceived organizational support significantly influenced job satisfaction, organizational commitment. and service quality. Second, Job satisfaction had a directional impact upon organizational commitment and service quality. Third, organizational commitment showed to have a predictive impart on service quality. Finally, the results of the study provide some insight into the types of internal marketing strategies that can be applied successfully by operators of hotel F & B departments.

The Effect of Buoyancy Orientation on Flow Structures in Turbulent Channel Flow using DNS

  • El-Samni Osama;Yoon HyunSik;Chun Ho Hwan
    • Journal of Ship and Ocean Technology
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    • v.9 no.4
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    • pp.1-10
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    • 2005
  • The effect of buoyancy orientation on turbulent channel flow has been investigated using DNS (direct numerical simulation). Grashof number is kept at 9.6 $\times 10^{5}$ while changing the orientation of the buoyancy vector to be parallel or perpendicular to the channel walls. Four study cases can be distinguished during this research namely; streamwise, wall-normal unstable stratification, wall-normal stable stratification and spanwise oriented buoyancy. The driving mean pressure gradient used in all cases is adjusted to keep mass flow rate constant while friction Reynolds number is around 150. At this Grashof number, the skin friction shows decrement in the unstable and stable stratification and increment in the other two cases. Analyses of the changes of flow structure for the four cases are presented highlighting on the mean quantities and second order statistics.

The Effects of Role Type on the Life Satisfaction of the Elderly in Rural Areas (농촌 노인의 역할유형이 생활만족도에 미치는 영향)

  • Lee, Mi Young
    • Journal of Family Resource Management and Policy Review
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    • v.23 no.1
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    • pp.99-113
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    • 2019
  • The purpose of this study was to investigate the role types that affect the life satisfaction of the elderly in rural areas. The research subjects were 1,000 people aged 65 years and over living in the rural areas of Korea. The data were analyzed using frequency analysis, descriptive statistics, and multiple regression analysis. The results of the study were as follows: First, as a result of substituting the role of rural elderly people into the role type of Rosow, the family role was drastically decreased, the health and self-management roles were increased and the social role was not changed much. In other words, the role type of the rural elderly supported the hypothesis proposed by Rosow. Second, life satisfaction was affected by monthly living expenses, social role, educational level, gender, farm, and religion. In order to improve the life satisfaction of the rural elderly, it is necessary to build programs and infrastructures that can play social roles in rural areas.

Risk Perception and Safety Knowledge of Scuba Divers

  • Cho, Byung-Jun;Ko, Jang-Sik;Kim, Gyoung-Yong;Kim, Yong-Seok
    • Journal of the Korea Society of Computer and Information
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    • v.24 no.5
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    • pp.131-137
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    • 2019
  • This study was aimed to identify a study on risk perception and safety knowledge and awareness of scuba diver. In order to achieve this purpose, a total of 310 customers over the age of 20 were selected as study participants form diving pools and dive resort in Seoul, Gyeonggi, Gangwon, Gyeongsang area using the convenience sampling method. However, only data from 295 customers were used after screening the data for reliability. The instrument for data collection was a questionnaire, and descriptive statistics, inter-item consistency reliability, t-test, ANOVA, post hoc test, correlation analysis, pearson chi-square test were conducted on the data using the SPSS 21.0 version statistical package program. The followings are the results: First, risk perception differs significantly according to age, education level, occupation and participation period. Second, participation period and safety knowledge have positive correlation.

The Effect of Leisure Satisfaction of the Elderly in China on Their Self-Efficacy and Psychological Well-Being in Calligraphy Activities (서예활동에 대한 노인의 여가만족이 자기효능감 및 심리적 안녕감에 미치는 영향)

  • Qin Yu;Feng Meng;Lee Jaewoo
    • The Journal of the Convergence on Culture Technology
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    • v.10 no.2
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    • pp.365-371
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    • 2024
  • The purpose of this study was to investigate the effect of leisure satisfaction according to calligraphy activities of the elderly on self-efficacy and psychological well-being. In order to conduct this study, the researchers surveyed 306 elderly people aged 65-76 or older from late November to early December 2023 in Anyang City and Xinxiang City, Henan Province, China. In order to verify the research hypothesis, the researchers performed frequency analysis, descriptive statistics analysis, and Pearson correlation analysis using IBM SPSS Statistics 25, and then performed independent sample T-test and one-way analysis of variance (One-Way ANOVA). To verify the hypothesis through the measurement concept, related verification was conducted for Hayes PROCESS macro and Bootstrap. As a result of the study, first, there is a gender difference in leisure satisfaction, leisure satisfaction, self-efficacy, and psychological well-being, and leisure satisfaction and psychological well-being differ significantly according to age. Second, it was found that leisure satisfaction had a positive effect on self-efficacy. Third, it was found that leisure satisfaction had a positive effect on psychological well-being. Fourth, leisure satisfaction was found to have a positive effect on psychological well-being. Therefore, in order to increase the leisure satisfaction and psychological well-being of the elderly, it is necessary to carefully develop a calligraphy activity system to increase self-efficacy.