• 제목/요약/키워드: Student-t Distribution

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빅데이터 연구동향 분석: 토픽 모델링을 중심으로 (Research Trends Analysis of Big Data: Focused on the Topic Modeling)

  • 박종순;김창식
    • 디지털산업정보학회논문지
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    • 제15권1호
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    • pp.1-7
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    • 2019
  • The objective of this study is to examine the trends in big data. Research abstracts were extracted from 4,019 articles, published between 1995 and 2018, on Web of Science and were analyzed using topic modeling and time series analysis. The 20 single-term topics that appeared most frequently were as follows: model, technology, algorithm, problem, performance, network, framework, analytics, management, process, value, user, knowledge, dataset, resource, service, cloud, storage, business, and health. The 20 multi-term topics were as follows: sense technology architecture (T10), decision system (T18), classification algorithm (T03), data analytics (T17), system performance (T09), data science (T06), distribution method (T20), service dataset (T19), network communication (T05), customer & business (T16), cloud computing (T02), health care (T14), smart city (T11), patient & disease (T04), privacy & security (T08), research design (T01), social media (T12), student & education (T13), energy consumption (T07), supply chain management (T15). The time series data indicated that the 40 single-term topics and multi-term topics were hot topics. This study provides suggestions for future research.

Mechanical Properties of W-X (X=Cu, Ag or BAg-8) Composites

  • Hanado, H.;Hiraoka, Y.;Inoue, T.;Akiyoshi, N.
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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    • pp.1054-1055
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    • 2006
  • Bend tests were performed at temperatures between 77 and 473K for W-19vol%Cu, W-22vol%Ag and W-19vol%(BAg-8) composites. Yield and maximum strengths and ductility of the composite were discussed in terms of microstructure and fractography. Results are summarized as follows. (1) Almost no difference was recognized in yield strength between the composites. In contrast, a large difference was recognized in maximum strength and ductility between the composites. (2) Inferior mechanical properties of W-Ag composite to W-Cu composite are attributed to heterogeneous distribution of Ag-phases, whilst inferior mechanical properties of W-(BAg-8) composite to W-Cu composite are attributed to large pores at grain boundaries.

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가정간편식의 제품속성에 대한 인식차이: 대학생들과 소비자를 중심으로 (Different Perception on Product Attributes of HMR: Focusing on College Students and Consumers)

  • 양회창;김종백;김안식
    • 유통과학연구
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    • 제14권2호
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    • pp.47-56
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    • 2016
  • Purpose - The purpose of this study is to investigate the difference in the degree of significance and satisfaction perceived by college students and ordinary consumers on the HMR product attributes. Comparison of the difference on HMR product attributes between ordinary consumers and college students who belong to the current and future consumption groups of HMR will provide information for clear marketing strategies and PR on target consumers from the aspects of companies. Also, overall difference on HMR was investigated through IPA(importance-performance analysis) on significance and satisfaction with each product attribute. This result will provide information to food companies that produce or supply HMR products to be supplemented and improved. Finally, IPA was conducted between groups on product attribute to find which difference exists between groups. This result is also expected to provide crucial information to companies as suggested in the first purpose. Research design, data, and methodology - The procedure of analysis is as follows. First, independent sample t-test was conducted on the significance and satisfaction on HMR product attributes. Second, with using IPA, the significance and satisfaction on HMR product attributes of the respondents were checked to investigate marketing strategy direction on overall HRM products. Third, the difference between generations was verified using IPA on the college student and consumer groups. According to this result, the direction of marketing strategy on HRM products was to be proposed to food companies. Results - It was known that consumers consider HMR product attributes statistically and significantly such as nutrient content(nutrition), country of origin, brand, main raw material, packaging, and awareness of manufacturer. They keep after purchase more importantly than college students who considered only volume and price than consumers. In comparison with the difference in satisfaction on HMR product attributes, the college student group was more satisfied than ordinary consumers only in flavor, condition of food additives, and volume. Also, HMR related food companies must maintain taste, cooking method, manufacturing date, expiration date, and safety on current products continuously. Finally, as a result of analysis from the groups, the attributes such as cooking method, manufacturing date, expiration date, and safety were considered significantly with high achievement by the two groups. It was known that college students considered food texture to be important, but consumers considered storage method to be important after purchasing it. Conclusions - There is necessity to differentiate effectiveness of products when releasing HMR products subject to consumers and college students. The result will give great assistance to the improvement of companies, produce or supply HMR products. It will also provide entry strategies on target groups of companies that are planning for entry. The factors that consumers commonly considered not to be significant were brand, package form(appearance), cooking time, and sale(purchase) location, which were found in the comparison with the groups that awareness about manufacturers and storage method after purchase corresponded to college students and that distribution route corresponded to ordinary consumers.

Bootstrap simulation for quantification of uncertainty in risk assessment

  • Chang, Ki-Yoon;Hong, Ki-Ok;Pak, Son-Il
    • 대한수의학회지
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    • 제47권2호
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    • pp.259-263
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    • 2007
  • The choice of input distribution in quantitative risk assessments modeling is of great importance to get unbiased overall estimates, although it is difficult to characterize them in situations where data available are too sparse or small. The present study is particularly concerned with accommodation of uncertainties commonly encountered in the practice of modeling. The authors applied parametric and non-parametric bootstrap simulation methods which consist of re-sampling with replacement, in together with the classical Student-t statistics based on the normal distribution. The implications of these methods were demonstrated through an empirical analysis of trade volume from the amount of chicken and pork meat imported to Korea during the period of 1998-2005. The results of bootstrap method were comparable to the classical techniques, indicating that bootstrap can be an alternative approach in a specific context of trade volume. We also illustrated on what extent the bias corrected and accelerated non-parametric bootstrap method produces different estimate of interest, as compared by non-parametric bootstrap method.

초.중.고 학생의 식생활 실태 및 인식 비교 연구 (A Comparative Study on Dietary Life and Recognition of Diet Related Factors in Elementary, Middle and High School Students)

  • 이보숙
    • 대한영양사협회학술지
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    • 제10권3호
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    • pp.364-374
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    • 2004
  • This Study was carried out to investigate dietary life and recognition of diet related factors in elemantary, middle and high school students. This study was surveyed by questionnaires and data were analyzed by SPSS program. Comparative analysis was conducted according to three school student groups(elementary childrens, middle school students, high school students). The subjects were 1,886 school students(female 893, male 959) of 51 schools in nationalwide region. The Distribution of subjects was elementary school childrens 544, middle school students 661 and high school students 681. The results are summarized as follows. Only Sixty percent of the subjects had breakfast regularly. About one forth of the subjects had the habit of skipping breakfast or eating 2-3 times per week. Pricipal reasons of skipping breakfast were 'busy'(50.7%) and 'not delicious or poor appetite'(31.0%). Regularity of having breakfast and reasions of skipping breakfast were significant differences according to school student groups(p<0.001 respectively). About half of the subjects didn't have sufficient amounts in breakfast. Most subjects(92.1%) had lunch regularly by virtue of school lunch service. One forth of the subjects had dinner irregularly. Pricipal reasons of skipping dinner were 'not delicious'(41.7%), 'busy'(15.1%) and 'weight loss'(14.3%). Regularity of having dinner and reasons of skipping dinner were significant differences according to school student groups(p<0.01, p<0.001 respectively). The most delicious meal was dinner in 56.7% of the subjects and lunch in 37.1% of the subjects. There was significant difference in recognition of most delicious meal according to school student groups(p<0.001). Only ten percent of the subjects thought that nutrition education was not needed. Diettitian was recognized as nutrition educator in sixty percent of the subjects. Only 5 percent of the subject recognized teacher as nutrition educator. There were not significant differences in most delicious meal and nutrition educator according to operation type of school lunch service. The findings suggested continuous attention and guidance for healthy dietary life and necessity of nutrition education for both school students and their parents.

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대학생의 성역할정체감과 건강행위 (Sex Role Identity and Health Behavior among University Student)

  • 박은옥;박영숙
    • 여성건강간호학회지
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    • 제5권3호
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    • pp.362-378
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    • 1999
  • This study is to investigate sex role identity and health behavior among university students in Seoul, during the late of 1999. The instruments for data obtainment were KSRI of Kim(1994), and Health Style : A Self-Test provided by ODPHP National Health Information Center. These instrument were reliable, showing Cronbach $\alpha$ .98 and .77. Frequency, t-test, $x^2$-test, stepwise regression were conducted for data analysis, using SAS 6.12 program. The major findings were as follows : 1. For female student. Androgeny(34.0%)type was most common and subjects of feminity type were 28.7%. In contrast, Masculinity type(41.8%) was most prevalent. and undifferentiated type was 30.1% among male students. There were significant difference between male and female student in the type of sex role identity. 2. 89.6% of all subjects were included in risk group for exercise and physical activity, 86.4% for diet habit, 43.2% for alcohol drinking and drug use, 35.6% for stress control, 32.8% for safety behavior, 24.8% for smoking. The big health risk behavior problem of male students were smoking, drinking, diet habit, and exercise. The important health risk behavior problem were diet habit and exercise. There were significant difference in smoking, drinking, exercise between sex. 3. Analysis of the distribution by sex role identity type and health behavior revealed that subjects who were undifferentiated typed group had high risk behavior in stress control, safety, exercise, drinking. Smoking and drinking were more problematic for masculinity typed group had high risk behavior in diet and exercise. The data showed that androginy typed group had more healthy behavior, compared with other sex role identity typed group for all of health behavior. Further research is need to understand the role of sex role identity in health behavior, the variables associated with them. And sex role identity has to be considered in research and practice about health promotion.

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중학생의 부모-자녀간 의사소통과 자아존중감 (Communication and Self-Esteem between Middle School Students and Their Parents)

  • 신효식;김근화
    • 한국가정과학회지
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    • 제7권2호
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    • pp.47-58
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    • 2004
  • This study is designed to provide some basic materials for finding better ways to promote student-parent communication in order to elevate the sense of self-esteem among middle school students and to talk about the importance of communication between students and parents through looking at the current student-parent communication reality resulting from socio-demographic changes among male and female middle school students and analyzing some influences student-parent communication has on students' self-esteem. To attain the aforementioned purpose, total 650 2nd grade and 3rd grade middle school students were asked to fill out the questionnaire. The schools that they are attending are 2 schools in Gwangju City and 2 schools in a township in Jeonnam. 617 students responded to the survey. In order to see the general characteristics and the distribution of major variables of the respondents, the data were used to produce frequency. percentile, standard deviation and correlation quotient. and t-test. one-way Anova, Duncan's multiple range test and multiple regression analysis techniques were put to use. The results from this study are as follows: student groups that have good relations with other students seemed to be more open and active in their communication with their mother and father. Female students and students in their 2nd grade had more open talking relations with their mothers than male students and students in their 3rd grade. Students had more open talking relations with their father when father's occupation is office worker. In the difference of self-esteem that results from variables in communication between students and parents, a significant variance was presented in the level of the self-esteem of middle school students. When they had open communication with both parents, they had a high sense of self-esteem. and when their communication style was problematic, they had a low sense of self-esteem. When they had better relations with other students, when they had more open communication styles with their mother, when they had better school records, when they felt more satisfaction with communication With their father, they showed a higher level of self-esteem.

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일반화 자기회귀 조건부 이분산 모형을 이용한 한국프로야구 관중수의 예측 (Forecasting attendance in the Korean professional baseball league using GARCH models)

  • 이장택;방소영
    • Journal of the Korean Data and Information Science Society
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    • 제21권6호
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    • pp.1041-1049
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    • 2010
  • 한국프로야구에서 관중수는 프로야구 발전을 위한 가장 큰 수입원이며 프로야구팀의 관심사이므로 수요예측 모형이 있다면 프로야구구단들은 관중유치 전략을 세우는데 도움이 될 것이다. 이러한 이유로 본 연구에서는 한국프로야구 관중수를 예측하는 모형을 제안하고자 하며 제한된 여건 속에서 관중수에 영향을 미치는 이용 가능한 대부분의 변수들을 고려하였다. 종속변수는 로그관중수로 두고 다양한 독립변수와 오차항의 분산을 등분산, 조건부 이분산을 가정한 여러 가지 일반화 자기회귀 모형, 오차항의 분포가 t분포를 따른다는 가정을 이용한 일반화 자기회귀 조건부 이분산 모형들을 서로 비교하였는데, 그 결과 고려된 모형 중에서는 t분포를 가정한 일반화 자기회귀 조건부 이분산 모형이 가장 예측력이 뛰어났다.

임플란트 치은열구내 red complex의 분포 (The distribution of red complex of implant sulcus)

  • 손고운;권영혁;박준봉;허익;정종혁
    • Journal of Periodontal and Implant Science
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    • 제36권1호
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    • pp.211-221
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    • 2006
  • The aim of present study was to evaluate the influence of periodontal status of adjacent tooth and loading time to the prevalence of red complex of implant sulcus. In 97 patients, partially edentulous subjects with endosseous root-form implants were selected. All subjects were medically healthy and had not taken systemic antibiotics and professional plaque control 3 months before sampling. The number was as follows: clinically healthy implants:161, clinically unhealthy implants:22, clinically healthy adjacent teeth:73, clinically unhealthy adjacent teeth:38. All teeth and implants of each patient were examined probing depth(PD), modified sulcus bleeding index(mSBI), and modified plaque index(mPI), and samples of subgingival plaque were obtained at each site with sterile curet or fine paper points, then the plaque transferred to PBS. Obtained samples were examined for the presence of P. gingivalis, T. forsythensis, and T. denticola by the polymerase chain reaction (PCR). The relationship among clinical parameters and the colonizations by the 3 bacterial species from adjacent teeth and implants region were analyzed by student t-test (p<0.05). The results of this study were as follows: 1. mPI and mSBI of implant increased with increasing of same indices of adjacent tooth(p=0.03,0.001), but not in the PD . 2. The mPI, mBI, PD of implants was higher when red complex exist. 3. The prevalence of red complex was higher when the periodontal condition is unhealthy. 4. The prevalence of red complex of implants has no significant relation to the probing depth of adjacent tooth. 5. Prevalence of P. gingivalis, T. forsythensis of implants increased with loading time. (p=0.02,0.018) These results shows the importance of oral hygiene and supportive periodontal therapy.

월경병과 하악부 면포 발생과의 관계에 대한 임상적 고찰 (A Clinical Analysis of the Correlation between Acne Distribution in the Jaw and Emmeniopathy)

  • 유현정;이승덕;최인화
    • 한방안이비인후피부과학회지
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    • 제17권2호
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    • pp.87-93
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    • 2004
  • Objective: We would like to find out the correlation between acne distribution in the jaw and the emmeniopathy. Methods: The clinical studies were made on 43 cases of acne vulgaris who visited to Department of Dermatology, Dongguk University Gangnam Oriental Medical Hospital during from August, 2002 to July, 2004. We divided the patients into two groups. A group had the emmeniopathy. B group didn't have the emmeniopathy. In the acne grade and the number of acne, we investigated the difference between A and B group statistically. We used the statical methods of student's t-test on the number of acne and wilcoxon rank sum test on acne grade. Results: The mean age was 25.8${\pm}$4.80 in A group and 27.6${\pm}$5.68 in B group. There were painful menstruation, quality of thickness, menstrual cycle disorder, menstrual amount disorder, dark purple color, premenstrual acne in A group with the emmeniopathy. The acne grade was 1.69${\pm}$1.28 in A group, 1.43${\pm}$1.28 in B group. The number of acne was 3.66${\pm}$3.15 in A group, 4.36${\pm}$4.07 in B group. P-value was 0.52 in acne grade and 0.25 in the number of acne. We investigated no difference between A and B group statistically on acne grade and the number of acne. Conclusions: We needed the further study about the factor which affect on acne distribution and emmeniopathy.

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