• Title/Summary/Keyword: Latent mean Analysis

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Analyses of Forest Road Construction Policy Using LISREL Approach (리즈렐모형을 이용한 임도사업의 계량적 분석)

  • Choi, Kwan
    • Journal of Korean Society of Forest Science
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    • v.97 no.1
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    • pp.22-29
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    • 2008
  • The objective of this study is to provide useful information for the establishment of efficient policy implementation strategies of forest road construction policy in South Korea. Data needed for the analysis was collected by a questionnaire survey. For the analysis, policy evaluation model was constructed based on theories of public policy. Evaluation model contains three independent variables (policy initiative factor, policy content, policy environment) and two dependent variables (policy result, policy impact). Since, these variables are unobservable latent variables, observable indicators are needed as proxy measures. LISREL (Linear Structural Relationships) was employed for the analysis since it is a useful measure for analysing linear structural model which consists of structural and measurement equations. It was confirmed that forest road construction is an effective policy mean for the development of rural region and activating forest resources management. The policy outcome, however, was not satisfactory. To improve the effectiveness of forest road construction policy some modification of policy contents are needed such as increased construction budget, allowing more flexibility and participation to the implementation personal and providing technical support.

A Data-based Sales Forecasting Support System for New Businesses (데이터기반의 신규 사업 매출추정방법 연구: 지능형 사업평가 시스템을 중심으로)

  • Jun, Seung-Pyo;Sung, Tae-Eung;Choi, San
    • Journal of Intelligence and Information Systems
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    • v.23 no.1
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    • pp.1-22
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    • 2017
  • Analysis of future business or investment opportunities, such as business feasibility analysis and company or technology valuation, necessitate objective estimation on the relevant market and expected sales. While there are various ways to classify the estimation methods of these new sales or market size, they can be broadly divided into top-down and bottom-up approaches by benchmark references. Both methods, however, require a lot of resources and time. Therefore, we propose a data-based intelligent demand forecasting system to support evaluation of new business. This study focuses on analogical forecasting, one of the traditional quantitative forecasting methods, to develop sales forecasting intelligence systems for new businesses. Instead of simply estimating sales for a few years, we hereby propose a method of estimating the sales of new businesses by using the initial sales and the sales growth rate of similar companies. To demonstrate the appropriateness of this method, it is examined whether the sales performance of recently established companies in the same industry category in Korea can be utilized as a reference variable for the analogical forecasting. In this study, we examined whether the phenomenon of "mean reversion" was observed in the sales of start-up companies in order to identify errors in estimating sales of new businesses based on industry sales growth rate and whether the differences in business environment resulting from the different timing of business launch affects growth rate. We also conducted analyses of variance (ANOVA) and latent growth model (LGM) to identify differences in sales growth rates by industry category. Based on the results, we proposed industry-specific range and linear forecasting models. This study analyzed the sales of only 150,000 start-up companies in Korea in the last 10 years, and identified that the average growth rate of start-ups in Korea is higher than the industry average in the first few years, but it shortly shows the phenomenon of mean-reversion. In addition, although the start-up founding juncture affects the sales growth rate, it is not high significantly and the sales growth rate can be different according to the industry classification. Utilizing both this phenomenon and the performance of start-up companies in relevant industries, we have proposed two models of new business sales based on the sales growth rate. The method proposed in this study makes it possible to objectively and quickly estimate the sales of new business by industry, and it is expected to provide reference information to judge whether sales estimated by other methods (top-down/bottom-up approach) pass the bounds from ordinary cases in relevant industry. In particular, the results of this study can be practically used as useful reference information for business feasibility analysis or technical valuation for entering new business. When using the existing top-down method, it can be used to set the range of market size or market share. As well, when using the bottom-up method, the estimation period may be set in accordance of the mean reverting period information for the growth rate. The two models proposed in this study will enable rapid and objective sales estimation of new businesses, and are expected to improve the efficiency of business feasibility analysis and technology valuation process by developing intelligent information system. In academic perspectives, it is a very important discovery that the phenomenon of 'mean reversion' is found among start-up companies out of general small-and-medium enterprises (SMEs) as well as stable companies such as listed companies. In particular, there exists the significance of this study in that over the large-scale data the mean reverting phenomenon of the start-up firms' sales growth rate is different from that of the listed companies, and that there is a difference in each industry. If a linear model, which is useful for estimating the sales of a specific company, is highly likely to be utilized in practical aspects, it can be explained that the range model, which can be used for the estimation method of the sales of the unspecified firms, is highly likely to be used in political aspects. It implies that when analyzing the business activities and performance of a specific industry group or enterprise group there is political usability in that the range model enables to provide references and compare them by data based start-up sales forecasting system.

On Securing Continuity of Long-Term Observational Eddy Flux Data: Field Intercomparison between Open- and Enclosed-Path Gas Analyzers (장기 관측 에디 플럭스 자료의 연속성 확보에 대하여: 개회로 및 봉폐회로 기체분석기의 야외 상호 비교)

  • Kang, Minseok;Kim, Joon;Yang, Hyunyoung;Lim, Jong-Hwan;Chun, Jung-Hwa;Moon, Minkyu
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.21 no.3
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    • pp.135-145
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    • 2019
  • Analysis of a long cycle or a trend of time series data based on a long-term observation would require comparability between data observed in the past and the present. In the present study, we proposed an approach to ensure the compatibility among the instruments used for the long-term observation, which would allow to secure continuity of the data. An open-path gas analyzer (Model LI-7500, LI-COR, Inc., USA) has been used for eddy covariance flux measurement in the Gwangneung deciduous forest for more than 10 years. The open-path gas analyzer was replaced by an enclosed-path gas analyzer (Model EC155, Campbell Scientific, Inc., USA) in July 2015. Before completely replacing the gas analyzer, the carbon dioxide ($CO_2$) and latent heat fluxes were collected using both gas analyzers simultaneously during a five-month period from August to December in 2015. It was found that the $CO_2$ fluxes were not significantly different between the gas analyzers under the condition that the daily mean temperature was higher than $0^{\circ}C$. However, the $CO_2$ flux measured by the open-path gas analyzer was negatively biased (from positive sign, i.e., carbon source, to 0 or negative sign, i.e., carbon neutral or sink) due to the instrument surface heating under the condition that the daily mean temperature was lower than $0^{\circ}C$. Despite applying the frequency response correction associated with tube attenuation of water vapor, the latent heat flux measured by the enclosed-path gas analyzer was on average 9% smaller than that measured by the open-path gas analyzer, which resulted in >20% difference of the sums over the study period. These results indicated that application of the additional air density correction would be needed due to the instrument heat and analysis of the long-term observational flux data would be facilitated by understanding the underestimation tendency of latent heat flux measurements by an enclosed-path gas analyzer.

Antiepileptic Therapy for Latent Epilepsy (잠복성 간질에 대한 항간제 투여의 뇌파상 효과)

  • Park, Choong-Sub;Byun, Yung-Joo;Ha, Jung-Sang
    • Journal of Yeungnam Medical Science
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    • v.2 no.1
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    • pp.71-75
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    • 1985
  • The clinical state with EEG pattern similar to interval discharge of epileptics is named as latent epilepsy, which does not necessarily mean that the patient will develop epilepsy later. However, since there is possibility of developing epilepsy on later date, antiepileptic mainly dilantin was tried to control the abnormal EEG. Since January to October 1985, total 580 headache sases with more than moderately abnormal EEG Visited the Neurology clinic. Among them 162 cases with interval seizure pattern (ISP) of epilepsy were selected for the study. The main ISP was 1. diffuse theta and/or delta bursts and 2. spikes. Since the study is only analysis of clinical treatment of 162 cases Without previous planning based on financial aid, about 30% of the patients did not return after the 1st EEG examination, in 42% failed to follow the EEG after the treatment and only remaining 28% of the cases were studied. Among 29 patients who were treated with Dilantin 100mg tid po, 16 improved and 13 not. Of the 13, 4 showed partial Improvement and partial progression. Case 1. In 4 weeks of antiepileptic the ray (AR), spikes disappeared but in 2 months developed bursts. Case 2. In 17days of AR, spikes and bursts disappeared but in 3 months bursts reccured. Case 3. In 1 week of AR, bursts disappeared but spikes developed. Case 4. In 3 months of AR, no change of spikes and bursts and she discontinued the AR. In 6 months she developed grandmal seizure. Eighteen cases, treated with other drugs except antiepileptics, all showed improvement. The other drugs were vincaprol, polygammalon, aronamin, ATP and hydergine. The improved cases had spikes more often than theta bursts. In view of the small number of the cases due to dropping most patients out of present study, it is considered meaningless to perform statistical analysis. Further well planned study With more patients is to be expected.

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The MeSH-Term Query Expansion Models using LDA Topic Models in Health Information Retrieval (MeSH 기반의 LDA 토픽 모델을 이용한 검색어 확장)

  • You, Sukjin
    • Journal of Korean Library and Information Science Society
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    • v.52 no.1
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    • pp.79-108
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    • 2021
  • Information retrieval in the health field has several challenges. Health information terminology is difficult for consumers (laypeople) to understand. Formulating a query with professional terms is not easy for consumers because health-related terms are more familiar to health professionals. If health terms related to a query are automatically added, it would help consumers to find relevant information. The proposed query expansion (QE) models show how to expand a query using MeSH terms. The documents were represented by MeSH terms (i.e. Bag-of-MeSH), found in the full-text articles. And then the MeSH terms were used to generate LDA (Latent Dirichlet Analysis) topic models. A query and the top k retrieved documents were used to find MeSH terms as topic words related to the query. LDA topic words were filtered by threshold values of topic probability (TP) and word probability (WP). Threshold values were effective in an LDA model with a specific number of topics to increase IR performance in terms of infAP (inferred Average Precision) and infNDCG (inferred Normalized Discounted Cumulative Gain), which are common IR metrics for large data collections with incomplete judgments. The top k words were chosen by the word score based on (TP *WP) and retrieved document ranking in an LDA model with specific thresholds. The QE model with specific thresholds for TP and WP showed improved mean infAP and infNDCG scores in an LDA model, comparing with the baseline result.

Outlier Detection and Replacement for Vertical Wind Speed in the Measurement of Actual Evapotranspiration (실제증발산 측정 시 연직 풍속 이상치 탐색 및 대체)

  • Park, Chun Gun;Rim, Chang-Soo;Lim, Kwang-Suop;Chae, Hyo-Sok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.5
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    • pp.1455-1461
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    • 2014
  • In this study, using flux data measured in Deokgokje reservoir watershed near Deokyu mountain in May, June, and July 2011, statistical analysis was conducted for outlier detection and replacement for vertical wind speed in the measurement of evapotranspiration based on eddy covariance method. To statistically analyze the outliers of vertical wind speed, the outlier detection method based on interquartile range (IQR) in boxplot was employed and the detected outliers were deleted or replaced with mean. The comparison was conducted for the measured evapotranspiration before and after the outlier replacement. The study results showed that there is a difference between evapotranspiration before outlier replacement and evapotranspiration after outlier replacement, especially during the rainy day. Therefore, based on the study results, the outliers should be deleted or replaced in the measurement of evapotranspiration.

Structural Relationship among Self-Directed Learning Ability, Learner-Instructor Interaction, Learner-Learner Interaction, and Class Satisfaction in Online Learning Environments (온라인 학습에서 자기주도학습능력, 상호작용 및 수업만족도의 구조적 관계)

  • Yoo, Jieun
    • Journal of Christian Education in Korea
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    • v.63
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    • pp.255-281
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    • 2020
  • The purpose of this study was to investigate the structural relationship among self-directed learning ability, learner-instructor interaction, learner-learner interaction, and class satisfaction in online learning environments by the structural equation modelling (SEM). Participants of the study consisted of 300 students (110 = high school students, 190 = college students). Through latent mean analysis (LMA), there was no significant difference of study variables between high school and college groups. However, thorough multi-group analysis, self-directed learning ability had a direct and indirect effect on class satisfaction for the college group via learner-instructor and learner-learner interactions, while learner-learner interaction played a full mediating role of the relationship between self-directed learning ability and class satisfaction for the high school group. In addition, self-directed learning ability had a stronger influence on learner-learner interaction for the college group than the high school group. These results would provide important implications for understanding the different mechanisms between high school and college online learning contexts.

Analysis of performance and combustion characteristics of D.O./butanol blended fuels in a diesel engine (디젤기관에서 경유/부탄올 혼합연료의 기관성능 및 연소특성 해석)

  • KIM, Sang-Am;WANG, Woo-Gyeong
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.55 no.4
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    • pp.411-418
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    • 2019
  • In this study, to investigate the effect of physical and chemical properties of butanol on the engine performance and combustion characteristics, the coefficient of variations of IMEP (indicated mean effective pressure) and fuel conversion efficiency were obtained by measuring the combustion pressure and the fuel consumption quantity according to the engine load and the mixing ratio of diesel oil and butanol. In addition, the combustion pressure was analyzed to obtain the pressure increasing rate and heat release rate, and then the combustion temperature was calculated using a single zone combustion model. The experimental and analysis results of butanol blending oil were compared with the those of diesel oil under the similar operation conditions to determine the performance of the engine and combustion characteristics. As a result, the combustion stabilities of D.O. and butanol blending oil were good in this experimental range, and the indicated fuel conversion efficiency of butanol blending oil was slightly higher at low load but that of D.O. was higher above medium load. The premixed combustion period of D.O. was almost constant regardless of the load. As the load was lower and the butanol blending ratio was higher, the premixed combustion period of butanol blending oil was longer and the premixed combustion period was almost constant at high load regardless of butanol blending ratio. The average heat release rate was higher with increasing loads; especially as butanol blending ratio was increased at high load, the average heat release rate of butanol blending oil was higher than that of D.O. In addition, the calculated maximum. combustion temperature of butanol blending oil was higher than that of D.O. at all loads.

Dream Content Analysis of Koreans in Their Twenties Using Hall/Van de Castle System (Hall/Van de Castle System을 이용한 20대 한국 남녀의 꿈 내용 분석)

  • Chang, Sok-Ha;Lee, Heon-Jeong;Kim, Leen
    • Sleep Medicine and Psychophysiology
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    • v.11 no.2
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    • pp.89-94
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    • 2004
  • Objectives: In the past, latent dreams were emphasized in the psychiatric field, but these days the interest in manifest dreams is increasing as ego psychology develops. Hall and Nordby proposed that there are similarities between manifest dreams and real life. The Hall/Van de Castle System is a method of dream content analysis, which considers both the quantitive and qualitive analytic aspects of manifest dreams. Methods: The dreams of 232 males and females (M:F=127:105;mean age=21.02.7) were collected through the Most Recent Dream Method. Collected data were analyzed using the Hall/Van de Castle System. Results: Female subjects tended to be more detailed and meticulous in reporting their dreams. The dreams of male subjects showed a higher percentage in self-negativity (2=6.64, df=1, p=0.004), and the dreams of female subjects showed a higher percentage in group character (2=6.64, df=1, p=0.0099), dreamer-involved success (2=3.12, df=1, p=0.048), and good fortune (2=4.52, df=1, p=0.034). Conclusion: This study suggests the norm of dream content of Korean college students, and it presents the differences between Korean males and females, and between Korean college students and American college students. This study may contribute to further studies on dream content analysis.

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A Study on the Clothing Behavior of Elementary School Students in Connection with Sex-Role Identity and Home Enviornments (초등학교 아동의 성역할 정체감 및 가정환경변인에 따른 의복행동연구)

  • Jeon, Kyoung-Ran
    • Korean Journal of Human Ecology
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    • v.6 no.2
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    • pp.133-144
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    • 1997
  • Clothing is considered as a means of self-projection in the childhood and children show clear preference on their own favorite clothing on which their latent identity is reflected. Changing sex-role identity, in particular, in the modern complex society specially affects the clothing behavior of children. The purpose of this study is to investigate the clothing behavior of children in conjunction with sen-role identity and home environment variables. This study will provide fundamental information on the clothing behavior in the childhood and be of help in selecting appropriate clothing in accordance with the variation of sex-role identity. Necessary information for this study was obtained through a questionaire. 'Bem sex-role identity inventory' was used to investigate the effect of sex-role identity and the clothing behavior was studied in conjunction with the factors of conformity, dependence, aesthetics and interest. The subjects of investigation are composed of three hundred male and female elementary school students in the 5th and 6th grades. For the statistical analysis of the collected data, percentage(%), mean value(M), standard deviation(SD) and Pearson's correlation coefficient were calculated and t-test, $x^2$-test, and Duncan's multiple range test were performed. The results form this study are as follows : 1. Sex-role identity shows a little difference according to gender, order of a birth and standard of living. This small difference is shown to be statistically insignificant. 2. In clothing behavior in connection with the sex-role identity, statistically significant trend was not found in typical sex-role identity group. However, clothing behavior in modernistic sex-role identity group exhibits statistically significant results in the factors of dependence, aesthetics and interest at the level of P<.001. 3. As concerns the clothing behavior in connection with gender, boy students show statistically more significant tendency in aesthetics and interest than girls do. However, boy students show statistically more significant tendency in aesthetics than girls do in connection with the standard of living. Although the clothing behavior associated with the level of parents education, mother's age and existence of mother's job shows a little difference in mean values, statistically significant trend was not detected. 4. Clothing behavior of the children shows a meaningful correlation between the factors. 5. Through 3-dimensional variables analysis, it is found that there is no mutual interaction between gender, sex-role identity and standard of living on the clothing behavior. The results from MCA supplementary analysis reveal that there is difference according to the gender, sex-role identity and standard of living.

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