• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.47-47
• /
• 2023

Drought occurs due to lack of water resources over an extended period and its intensity has been magnified globally by climate change. In recent years, drought over South Korea has also been intensed, and the prediction was inevitable for the water resource management and water industry. Therefore, drought forecasting over South Korea was performed in the current study with the following procedure. First, accumulated spring precipitation(ASP) driven by the 93 weather stations in South Korea was taken with their median. Then, correlation analysis was followed between ASP and Df4m, the differences of two pair of the global winter MSLP. The 37 Df4m variables with high correlations over 0.55 was chosen and sorted into three regions. The selected Df4m variables in the same region showed high similarity, leading the multicollinearity problem. To avoid this problem, a model that performs variable selection and model fitting at once, least absolute shrinkage and selection operator(LASSO) was applied. The LASSO model selected 5 variables which showed a good agreement of the predicted with the observed value, R²=0.72. Other models such as multiple linear regression model and ElasticNet were also performed, but did not present a performance as good as LASSO. Therefore, LASSO model can be an appropriate model to forecast spring drought over South Korea and can be used to mange water resources efficiently.

• Journal of Intelligence and Information Systems
• /
• v.6 no.2
• /
• pp.29-40
• /
• 2000

Process planning (selection and ordering of processes) and material selection for product manufacturing are two key things determined before taking full-scale manufacturing. Knowledge on product design. material characteristics, processes, time and cost all-together are mutually related and should be considered concurrently. Due to the complexity of problem, human experts have got only one of the feasilbe solutions with their field knowledge and experiences. We propose a hierarchical expert system framework of knowledge representation and reasoning in order to overcome the complexity. Manufacturing processes have inherently hierarchical relationships, from top level processes to bottom level operation processes. Process plan of one level is posted in process blackboard and used for lower level process planning. Process information on blackboard is also used to adjust the process plan in order to resolve the dead-end or inconsistency situation during reasoning. Decision variables for process, material, tool, time and cost are represented as object frames, and their relationships are represented as constraints and rules. Constraints are for relationship among variables such as compatibility, numerical inequality etc. Rules are for causal relationships among variables to reflect human expert\`s knowledge such as process precedence. CRSP(Constraint and Rule Satisfaction Problem) approach is adopted in order to obtain solution to satisfy both constraints and rules. The trade-off procedure gives user chances to see the impact of change of important variables such as material, cost, time and helps to determine the preferred solution. We developed the prototype system using visual C++ MFC, UNIK, and UNlK-CRSP on PC.

• Phonetics and Speech Sciences
• /
• v.7 no.4
• /
• pp.59-65
• /
• 2015

This study was conducted to identify the differences in voice characteristic variables before and after taking a certain amount of high-caffeine. Linear PCM-M10 Recorder (SONY) was used for the recorder and basic frequency of the voice (Fo), frequency fluctuation rate (jitter), amplitude fluctuation rate (shimmer) and Signal-to-Noise Ratio (SNR) were measured using TF-32(University of Wisconsin-Madison, USA). First, prolonged phonation analysis results of /ah/ by male subjects showed the shimmer values after taking high-caffeine increased statistically significantly(p<.05) compared with before the intake and SNR values significantly decreased. (p<.05). On the other hand, female subjects didn't show any statistically significant differences in all variables. Second, male subjects showed statistically significant increased shimmer values after the intake compared with before the intake at /ah/ of syllable 'na' and /ah/ in 'ra' in 'autumn' paragraph (p<.05), and jitter values significantly increased at /ah/ in 'ah' (p<.05). However, female subjects didn't show any statistically significant differences in all variables. Results of this study showed that high-caffeine intake more affects male subjects than female subjects. In male subjects, shimmer and SNR changed at vowel prolonged phonation, /ah/, and study results showed that shimmer and SNR in 'Autumn' paragraph /na/, /ra/ and jitter in /ah/ could be identified as the variables to show the voice change.

• Journal of Nutrition and Health
• /
• v.34 no.2
• /
• pp.222-229
• /
• 2001

This study describes the application of the stages of change construct to fat intake by examining the associations of the stages of change with nutritional status and beliefs on health behavior. Data were obtained from apparently healthy 596 adults(326 females and 270 males) residing in large cities. Stages of change assessed by an algorithms based on 6 items were designed each subject into one of the 5 stages: precontemplation(PC), contemplation(CO), preparation(PR), action(AC) and maintenance(MA). Beliefs on health behavior were assessed by self efficacy as well as 4 belief scales from the Locus of Illness Control(LIC) developed using factor analysis such as internal disease cure and prevention and external disease cure and prevention. Energy and fat intakes were measured by a 39 item short form food frequency questionnaire. Regarding the 5 stages of change, MA stage comprised the largest group(37.9%), followed by Ac(30.7%), PC(11.4%), CO(10.4%) and PR(9.6%). Subjects who were females, older or healthier were more likely to belong to either AC or MA. Stage assignment of individuals was corroborated by their nutritional variables. Those in PC had the most energy and fat and those in MA ate the least for females. BMI was higher in PR than any other stages for both males and females. Those in PC were distinctive in that they were more externally oriented in terms of health control showing higher scores on external disease prevention(for males) and external disease cure(for females), and lower score on internal disease cure. On the other hand, those in MA received the highest scores on internal disease prevention and self efficacy, which suggested that they were more internally oriented. Canonical discriminant function analysis indicated that the 5 stages were importantly discriminated by BMI, self efficacy, internal disease prevention and external disease prevention for males and by fat intake, self efficacy and external disease cure variables for females. The results of our study confirm differences in stages of change in fat intake in terms of nutritional status and beliefs on heath behavior and indicate the need for taking these phases of change into account in nutrition advice. (Korean J Nutrition 34(2) : 222-229, 2001)

• The Korean Journal of Applied Statistics
• /
• v.21 no.5
• /
• pp.875-888
• /
• 2008

Mosaic plots, proposed by Hartigan and Kleiner (1981, 1984), are very useful in visualizing categorical data. In mosaic plot, multi-way classified cell frequencies are represented by rectangles with proportional area. The plot is easy to understand while preserving the information contained in the data. Plot's appearance, however, does change substantially depending on the order of variables and the orders of categories with variable put into the plot. In this study, we propose the algorithms for ordering variables and categories of the categorical data to be explored via mosaic plots. We demonstrate our methods to three well-known datasets: Titanic, Housing and PreSex.

• Journal of the Ergonomics Society of Korea
• /
• v.30 no.6
• /
• pp.757-764
• /
• 2011

Objective: The aim of this study was to provide a method to improve the compliance and reduce the time by reducing the workload during the model change work. Background: The enterprises are constructing the small quantity batch production system by increasing the number of model change and reducing model-changing. However, the compliance is low because the work is strenuous and high skills are needed, so the system management is facing with many difficulties. Method: After classifying the model change work according to the purposes(preparation, change and adjustment) with the target of mascara filling machine, element tasks time were measured and the motion analysis(therblig symbol) and REBA analysis were performed. The study incorporated 3 independent variables as the number of motion, REBA score and the element time. The dependent variable is the type of element work as preparation, change and adjustment. The statistical test was performed by one-way ANOVA(${\alpha}$ < 0.05). Results: For the preparation, the number of motions appeared in the order of Use(U), Transport Loaded(TL), and Position(P). The order appeared in change is Use(U), Release Load(RL), and Grasp (G). The adjustment appeared in the order of Position(P) and Use(U). The results of average motion time as the element work times divided by the number of motion appeared in the order of adjustment(1.85sec/motion), preparation(1.11sec/motion), and change(0.62sec/motion). The results of REBA showed that the average risk level of change and adjustment were medium, but 53.1% of change and 42.9% of adjustment were evaluated as high. Conclusion: Reducing the avoidance and improving the compliance of work could be expected if the job autonomy were improved by improving the working postures with high risk level. Application: It is expected to solve the problem of reducing the time of model change work in the small quantity batch production system. The future work is to carry out the improvement directions found in the results and compare the results after improvement.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.27 no.4
• /
• pp.52-64
• /
• 2019

The purpose of this study is to analyze the impact of macroeconomic variables on air passenger demand and provide useful information to airport managers and policymakers. Therefore, using the quarterly macroeconomic indicators from 2002 to 2017, the relationship with air passenger demand was demonstrated by multiple regression analysis. In the previous studies, they used GDP, Korea Treasury Bond, KOSPI index, USD/KRW Exchange Rate, and WTI Crude Oil Price variables. In this study, we used the Coincident Composite Index, Employment Rate, Consumer Sentiment Index, and Private Consumption Rate used as additional variables. It has confirmed that if the consumption of research results expands or the economic environment is right, it will affect the increase in international passengers. In other words, it confirmed that the overall economic situation acts as the main factor determining air passenger demand. It confirmed that the economic environment at the past has a significant impact on air passenger demand.

• Journal of Climate Change Research
• /
• v.5 no.2
• /
• pp.165-178
• /
• 2014

National and local governmental adaptation plan for climate change will become mandatory in 2015. In order to establish the plan, assessment of vulnerability to climate change needs to be preceded. LCCGIS, a toolkit for vulnerability assessment, has been widely used by many local governments. However, assessment results by LCCGIS are not yet reliable because most of the vulnerability indices applied to LCCGIS　have the same value for almost all administrative units in Korea. In this study, proxy variables for hard-collectable indices were introduced, and the results were compared with those without any proxy variables. Vulnerability assessment could be conducted subjectively due to uncertainty. Thus, determination of objective indices, understanding the available data, and changes of indices in local conditions were organized. Results from this study are expected to make vulnerability assessment reliable and contribute to assessing vulnerability to climate change reflecting on local governmental characteristics.

• Journal of Family Relations
• /
• v.22 no.4
• /
• pp.181-204
• /
• 2018

Objectives: The aim of this study is to integrate the results of the previous studies from 1900 to 2016 according to the types of dependent variables individually and statistically to obtain the results of the overall level of the marital education program I need to figure it out. In other words, the general and valid study on the overall effectiveness of the marriage education program will lead to more concluded conclusions and draw up an integrated and holistic conclusion about the effectiveness of the marriage education program. Method: The purpose of this study was to investigate the effect of married couples' education program on married couples' education program. The results of this study are as follows. First, Comprehensive Meta-Analysis. In other words, funnel plot, forest plot, and trim & fill were used to analyze all the variables related to the education of the couple, and homogeneity test After choosing an analytical model for the analysis, we calculated the 'standardized mean difference' effect size (d) that can compare different individual studies through the analytical model. The results of this study are as follows. Results: The purpose of this study was to investigate the overall effect size of domestic couples education programs after 1990, and to investigate the effect sizes of dependent variable types and program - related variables. First, the total effect size of the domestic marriage education program was close to the level of the large effect size and had a substantial and preventive effect. Self-esteem, communication, marital adjustment, emotion, and self control have a substantial and prophylactically significant change depending on the type of subordinate variables related to the marital education program But there was no change in origin family and life satisfaction. Third, as a result of the categorization of the dependent variable categorization of the Korean couple education program, it was found that the marital relations of the participant in the individual inner and the marital relations The effect was significant enough to change. Fourth, Korean couple education program was most effective when mixed age couples were participated in various family life cycle. Conclusions: Based on the results of this study, it is necessary to study more deeply about marital education program effect of marriage education for various special groups such as married couples who are in a crisis of divorce, . It also means that the results of the research for the last 30 years from 1900 to 2016 were comprehensively and systematically summarized through meta - analysis. The results of this study provide information on how to provide the most effective couples education programs for practitioners in the field. The result of this study will be the data of judgment about how to organize the marital education program for people of any ages and characteristics in the future.

• Journal of the Korea Concrete Institute
• /
• v.26 no.3
• /
• pp.267-275
• /
• 2014

Recently, the construction of curved bridge has increased, thus researchers perform the analytic studies on PSC curved bridge. However, the grid analysis method that are mostly used in the construction industry is not adequate to acquire the precise behavior evaluation of curved PSC briges. Therefore, the precise finite element analysis considering the effective variables were performed to establish the basis for the design method of curved PSC bridge by using 3D elements and bar element. The evaluated variables in this analysis were the number of girders, loading point, section figure, change of prestressing force. The results show the load carrying capacity of the 3 girder type bridge is 200% of that of the 2 girder type, and that applying load on outer girder makes the load resistance capacity and the deflection deviation of 2 girders smaller. The structural capacity of the bridge is improved when the section size is increased, but the efficiency of it is not sufficient enough compare to that of the change of prestressing forces. The change of prestressing forces shows that the camber and the load carrying capacity are linearly increased as PS force is increased. Moreover, when the PS force applied on outer girder is increased than that of inner girder, the deviation of deflection the girders decreases, thereby the stability of the bridge is enhanced.