• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.19-32
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• 2007

In Korea, there have been various methods of estimating groundwater recharge which generally can be subdivided into three types: baseflow separation method by means of groundwater recession curve, water budget analysis based on lumped conceptual model in watershed, and water table fluctuation method (WTF) by using the data from groundwater monitoring wells. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, so these methods have various limits to deal with these characteristics. To overcome these limitations, we present a new method of estimating recharge based on water balance components from the SWAT-MODFLOW which is an integrated surface-ground water model. Groundwater levels in the interest area close to the stream have dynamics similar to stream flow, whereas levels further upslope respond to precipitation with a delay. As these behaviours are related to the physical process of recharge, it is needed to account for the time delay in aquifer recharge once the water exits the soil profile to represent these features. In SWAT, a single linear reservoir storage module with an exponential decay weighting function is used to compute the recharge from soil to aquifer on a given day. However, this module has some limitations expressing recharge variation when the delay time is too long and transient recharge trend does not match to the groundwater table time series, the multi-reservoir storage routing module which represents more realistic time delay through vadose zone is newly suggested in this study. In this module, the parameter related to the delay time should be optimized by checking the correlation between simulated recharge and observed groundwater levels. The final step of this procedure is to compare simulated groundwater table with observed one as well as to compare simulated watershed runoff with observed one. This method is applied to Mihocheon watershed in Korea for the purpose of testing the procedure of proper estimation of spatio-temporal groundwater recharge distribution. As the newly suggested method of estimating recharge has the advantages of effectiveness of watershed model as well as the accuracy of WTF method, the estimated daily recharge rate would be an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers and aquifers.

• Information Systems Review
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• v.11 no.1
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• pp.161-179
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• 2009

Nowadays an increasing number of Internet users are running individual websites as Blog or Cyworld. As this type of personal media has a great influence on communication among people, business comes to care about Network Effect, Network Software, and Social Network. For instance, Cyworld created the web service called 'Minihompy' for individual web-logs, and acquired 2.4milion users in 2007. Although many people assumed that the popularity of Minihompy, or Blog would be a passing fad, Cyworld has improved its service, and expanded its Network with various contents. This kind of expansion reflects survival efforts from infinite competitions among ISPs (Internet Service Provider) with focus on enhancing usability to users. However, Cyworld's Network Effect is gradually diminished in these days. Both of low production cost of service vendors and the low searching/conversing costs of users combine to make ISPs hard to keep their market share sustainable. To overcome this lackluster trend, Cyworld has adopted new strategies and try to lock their users in their service. Various efforts to improve the continuance and expansion of Network effect remain unclear and uncertain. If we understand beforehand how a service would improve Network effect, and which service could bring more effect, ISPs can get substantial help in launching their new business strategy. Regardless many diverse ideas to increase their user's duration online ISPs cannot guarantee 'how the new service strategies will end up in profitability. Therefore, this research studies about Network effect of Cyworld's 'Minihompy' using System-Dynamics method which could analyze dynamic relation between users and ISPs. Furthermore, the research aims to predict changes of Network Effect based on the strategy of new service. 'Page View' and 'Duration Time' can be enhanced for the short tenn because they enhance the service functionality. However, these services cannot increase the Network in the long-run. Limitations of this research include that we predict the future merely based on the limited data. We also limit the independent variables over Network Effect only to the following two issues: Increasing the number of users and increasing the Service Functionality. Despite of some limitations, this study perhaps gives some insights to the policy makers or others facing the stiff competition in the network business.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.365-374
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• 2018

This study investigated the relationship between Vitamin D levels and indices related to cardiovascular disease in Korean adults aged ${\geq}19years$. The data for analysis were obtained from the sixth Korea National Health Nutrition Examination Survey in 2013 and 2014. The results showed that the incidence of Vitamin D deficiency was 73.1% among Korean adults and that indices related to cardiovascular disease showed an increasing trend (55.6% of Korean adults). The relationship between Vitamin D levels and indices related to cardiovascular disease with controlled physical activity status was also studied. The odds ratios (ORs) for age were 1.72 for the 4-62 years age group (95% CI, 1.53-1.93) and 2.05 for the ${\geq}65years$ age group (95% CI, 1.71-2.45). For blood pressure, the OR for pre-hypertension was 1.30 (95% CI, 1.15-1.47) and that for hypertension was 1.31 (95% CI, 1.11-1.54). For body mass index (BMI), the OR was 1.36 (95% CI, 1.11-1.66) and that for waist circumference (WC) was 1.36 (95% CI, 1.11-1.66). For fasting blood sugar (FBS), the OR for impaired fasting glucose (IFG) was 1.37 (95% CI, 1.21-1.55) and that for diabetes mellitus (DM) was 1.31 (95% CI, 1.05-1.65). The OR for total cholesterol (TC) was 1.30 (95% CI, 1.11-1.52) and that for triglycerides (TG) was 1.20 (95% CI, 1.04-1.37) in Korean adults. There was a significant relationship between Vitamin D and indices related to cardiovascular disease in Korean adults with respect to age, blood pressure, FBS, BMI, TC and TG. Confirmation of a causal relationship between Vitamin D and indices related to cardiovascular disease may require further research consisting of more systematic cohort studies.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.13 no.4
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• pp.211-216
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• 2018

This study was intended to analyze the effects of the selection of excellent design product by the KIDP(Korea Institute of Design Promotion) on the business performance of the company focused on the start-up with relatively low competitiveness. According to the statistics of KIDP in 2013, a design accounted for 27.53% of the factors affecting the sales of products and a design was the most important factor among the factors affecting the sales of products for the small sized company in terms of the scale of company. In addition, looking at the trend by industry in the data collected for this study, the technology-based industry showed a relatively higher growth rate than the retail industry and other industries. In this study, the author surveyed 186 companies of the companies that recognized the importance of design in difficult management conditions and received excellent design product certificate from KIDP(2013, 2014 and 2015) and empirically verified whether there was any difference in business performance between the start-ups with a business history of less than 7 years and the ongoing firms with a business history of more than 7 years. To evaluate the value of design, we used analytical method of measuring related values by comparison between groups. In addition, we also analyzed the difference in business performance(sales) between manufacturing companies, where the role of design was relatively large, and non-manufacturing companies among companies that received the excellent design product certificate. We have established a study hypothesis that the selection of excellent design product by the KIDP would have more positive effect on the business performance(sales) of the start-up compared to the ongoing firm, and conducted an empirical analysis by comparing both the year before and the year after the selected year. As a result, we found that the selection of excellent design product by the KIDP has a positive effect on the business performance of the start-up, and the selection of excellent design product has a significant effect on the difference in business performance between manufacturing and non-manufacturing companies. This study was conducted in the hope that the government actively supports the design-related policies so that the selection of excellent design product become an important indicator of the business performance of the start-up, and thus the design management will be a way to enhance the competitiveness of the start-up.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.3
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• pp.33-46
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• 2020

This study analyzes the entrepreneurship education phenomena for agri-food entrepreneurs whose main business is the production of agricultural products and the sale of processed products, using the qualitative study Strauss & Corbin(1998)'s evidence theory approach. From the entrepreneur's point of view, I would like to summarize the phenomena that appear in education, and to prepare a theoretical basis for explaining the phenomena. The importance of entrepreneurship education is emphasized to cultivate the ability to develop and provide products tailored to customers. The necessity of education leads to an increase in demand according to the situational awareness of the founders, and the quantitative increase in entrepreneurship education in the agri-food sector is a clear trend. Inevitably, the need for various discussions on systematic and effective entrepreneurship education is raised. For the study, an interview was conducted with preliminary or entrepreneur who have experienced entrepreneurship education in the agri-food sector. As a research method, I use Strauss & Corbin(1998)'s approach and analyze qualitative data using QSR's NVIVO 12 program. Through this study, it was found that contextual and systematic entrepreneurship education in the agri-food sector has the effect of strengthening competitiveness and strengthening sales. There is a need for follow-up management of trainees. Strengthening the competitiveness of start-ups is based on training professional manpower through education and linking regions with cities. Strengthening sales is based on product planning and market development. This study explores entrepreneurship education in the agri-food sector, which has not been actively conducted in the past. Exploratory analysis on the experiences of the founders of agri-food sector as education demanders has an important meaning for understanding the phenomenon of start-up education.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.65-78
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• 2006

This paper investigates the cost structure ot the Korea and Japan railroad industry with respect to density, scale and scope economies as well as productivity growth rate using a generalized trans)og multiproduct cost function model. The paper then assumes that the Korea and Japan railway companies pi·educe three outputs (incumbent railway passenger-kilometers. Shinkansen passenger-kilometers, ton-kilometers of freight) using four input factors (labor, fuel, maintenance, rolling stock and capital). The specified cost function includes foul other independent variables: track lengths to reflect network effects, two dummies to reflect nation and ownership effects, and time trend as a proxy for technical change. The simultaneous equation system consisting of a cost function and three input share equations is estimated with the Zellner's iterative seemingly unrelated regression. The unbalanced panel data used in the paper, a total of 154 observations. are collected from the annual records of the Korea National Railroad (KNR) for the yews $1977{\sim}2003$, Japan National Railways (JNR) for the years $1977{\sim}1984$. seven Japan Railways (JR's) for the years $1987{\sim}2003$. The findings show that the Korean and Japanese railways exhibit product-specific and overall economies of density but product-specific diseconomies of scale with respect to incumbent railway passenger-kilometers, Shinkansen-kilometers and ton-kilometers. However, the railways experience mild overall economies of scale which result from economies of scope associated with the joint production of incumbent railway/Shinkansen and feight, freight/incumbent railway and Shinkansen except Shinkansen/incumbent railway and freight. In addition, the economies of density and scale in the KNR, JR east, JR central, and JR west companies at the point of the years $1990{\sim}2003$ average is generally analogous to the above results at the point of sample average. There also appear to be economies of ssope associated with the joint Production of the incumbent railway and Shinkansen in JR central but diseconomies of scope in JR East and JR West. The findings also indicate that the productivity growth rate of the privately-owned JR's is larger than that of the government-owned KNR.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.511-525
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• 2003

The Okcheon Group in the southwestern part of the Okcheon Metamorphic Belt is subdivided into two distinct tectonostratigraphic units: the Boeun unit in the south and the Pibanryeong unit in the north. The Boeun unit consists of petites, psammites, carbonaceous petites, limestones and pebble-bearing quartzites. The Pibanryeong unit is composed of petites, well-sorted fine-grained psammites, carbonaceous psammites and quartzites. In order to outlining stratigraphy and depositional environments of the Okcheon Group, detailed stratigraphic sections were measured in three locations; one section(Gosan section) of the Boeun unit and two sections(Sorungjae and Hwangryeongzae sections) of the Pibanryeong unit. The Gosan section of the Boeun unit is interpreted to be deposited in the shallow marine environments, whereas the Sorungjae and Hwangryeonaiae sections of the Pibanryeong unit appear to be deposited in slope and deep basin environments. This result indicates rapid subsidence between deposition of the Boeun and Pibanryeong units in sedimentary environment. The trace of sedimentological environments in the Hwasan area was investigated by geochemical analysis of 109 metapelitic and psammitic rock samples. Distinct chemical variations of politic and psammitic rocks from the Boeun and Pibanryeong units in the study area are evident from plots of major elements and $A1_2O_3$/$SiO_2$ versus Basicity Index($Fe_2O_3{＋}MgO$)/($SiO_2{＋}K_2O{＋}Na_2O$). The rocks show a progressive chemical trend from the Boeun unit to the Pibanryeong unit on these diagrams. They in the southern sector of the Boeun unit display lower values and a comparatively wide range of $A1_2O_3$/$SiO_2$ and Basicity Index, as compared with those from the northern sector of the Boeun and Pibanryeong units. The southern sector of the Pibanryeong unit including narrow staurolite-bearing zone is characterized by values that are transitional between the Boeun and Pibanryeong units. These data, combined with depositional environment progressively deepened towards the northwest, support a half-graben model for the Okcheon basin, as proposed by Cluzel et al.(1990)

• Tuberculosis and Respiratory Diseases
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• v.58 no.4
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• pp.392-398
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• 2005

Background : The last national tuberculosis survey was carried out in 1995. In 2000, the KTBS(Korean Tuberculosis Surveillance System) replaced a previous national survey. However, the KTBS does not show some of the important epidemiological indexes such as the prevalence of positive tuberculosis or the drug resistance rate. The aim of this study was to compare the clinical features of pulmonary tuberculosis patients admitted to a national tuberculosis hospital in 1995 and 2002. From this study, the authors expect to estimate the trend of the clinical features of tuberculosis in Korea even though it can not represent the Korean tuberculosis situation as a whole. Method : A cross sectional analysis of the clinical features for 331 pulmonary tuberculosis in-patients admitted to the National Masan Tuberculosis Hospital as of Dec. 2002, was carried out and these results were compared with those reported in 1995. Results : In comparison with the data reported in 1995, the mean age was increased by 3.6 years ($44.1{\pm}14.6$ vs $47.7{\pm}16.4$, p<0.01). The number of past tuberculosis history and used anti-tuberculous drugs prior to admission decreased from $2.0{\pm}1.7$ and $6.1{\pm}2.3$ to $1.7{\pm}1.8$ and $4.6{\pm}3.6$(p<0.05, p<0.001), respectively. While the resistance rate for anti-tuberculous drugs was similar (81.0% vs 77.6%), the initial resistance rate(10.5% vs 21.4%) and initial MDR rate(2.4% vs 16.5%) increased significantly(p=0.012, p=0.001, respectively). In 1995, the public health communities were in charge of approximately 65% of newly diagnosed tuberculosis cases, but this reduced to 40.5% in 2002(p<0.001). Conclusion : The existing national TB program (NTP) needs to be revised and strengthened in order to cope with the unfavorably changing situation of the domestic TB problem because the number of TB patients has not decreased and the initial resistance rate has increased greatly. Furthermore, the public and private sectors should cooperate each other to control the TB problem effectively because the private sector is now managing more than half of the TB patients.

• The Journal of Korean society of community based occupational therapy
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• v.5 no.1
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• pp.11-21
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• 2015

Objective : This study is aimed to examine the degree of independence in stroke patients residing in a community based on their self-efficacy and Instrumental Activities of Daily Living and also correlation between community-residing stroke patients and their guardians by figuring out the life quality of their guardians. Methods : For total two weeks between May 12th and 23rd, 2014, this researcher collected data by using a survey (K-IADL, a scale to measure self-efficacy, WHOQOL-BREF) targeting 138 stroke patients who received over 24 points in MMSE-K among the outpatients of three hospitals located in Busan Metropolitan City and two hospitals located in Geoje-si, Gyeongsangnam-do, and total 125 sheets were finally used for analysis. Results : Among the 125 patients, 70 were males, and 55 were females, and their average age was 58.72 (16 to 82). The subjects' general self-efficacy (p<0.01) and detailed self-efficacy (p<0.01) indicated significant correlation with their guardian's life quality, and there was no significant correlation found between their Instrumental Activities of Daily Living and their guardian's life quality. Conclusion : Their general self-efficacy and detailed self-efficacy indicated correlation with their guardian's life quality, and among their general characteristics, the factor of their financial situation indicated correlation with their guardian's life quality. In conclusion, when stroke patients' self-efficacy is higher, their guardian's life quality increases, too, and if their financial situation is more favorable, their guardian's life quality gets higher. However, stroke patients' Instrumental Activities of Daily Living did not indicate correlation with their guardian's life quality. When looking at the chronic trend of outpatients, therapeutical plan must be established about the self-efficient recovery for the development of those who are not satisfied.

• Journal of the Korean association of regional geographers
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• v.7 no.3
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• pp.107-120
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• 2001

This study is concerned with providing a reliable procedure of calibrating a set of places specific distance parameters and with applying it to U.S. inter-State migration flows between 1985 and 1900. It attempts to conform to recent advances in quantitative geography that are characterized by an integration of ESDA(exploratory spatial data analysis) and local statistics. ESDA aims to detect the spatial clustering and heterogeneity by visualizing and exploring spatial patterns. A local statistic is defined as a statistically processed value given to each location as opposed to a global statistic that only captures an average trend across a whole study region. Whereas a global distance parameter estimates an averaged level of the friction of distance, place-specific distance parameters calibrate spatially varying effects of distance. It is presented that a poisson regression with an adequately specified design matrix yields a set of either origin-or destination-specific distance parameters. A case study demonstrates that the proposed model is a reliable device of measuring a spatial dimension of migration, and that place-specific distance parameters are spatially heterogeneous as well as spatially clustered.