• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1305-1309
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• 2013

The application of the superconducting fault current limiter (SFCL) in a power distribution system is expected to contribute the voltage-sag suppression of the bus line as well as the fault-current reduction of the fault line. However, the application effects of the SFCL on the voltage sag of the bus line including the fault current are dependent on its application location in a power distribution system. In this paper, we investigated the fault current limiting and the voltage sag suppressing characteristics of the SFCL due to its application location such as the outgoing point of the feeder, the bus line, the neutral line and the 2nd side of the main transformer in a power distribution system, and analyzed the trace variations of the bus-voltage and fault-feeder current. The simulated power distribution system, which was composed of the universal power source, two transformers with the parallel connection and the impedance load banks connected with the 2nd side of the transformer through the power transmission lines, was constructed and the short-circuit tests for the constructed system were carried out. Through the analysis on the short-circuit tests for the simulated power distribution system with the SFCLs applied into its representative locations, the effects from the SFCL's application on the power distribution system were discussed from the viewpoints of both the suppression of the bus-voltage sag and the reduction of the fault current.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.6
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• pp.19-30
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• 2016

The projection of climate-related range shift is critical information for conservation planning of Korean fir (Abies koreana E. H. Wilson). We first modeled the distribution of Korean fir under current climate condition using five single-model species distribution models (SDMs) and the pre-evaluation weighted ensemble method and then predicted the distributions under future climate conditions projected with HadGEM2-AO under four $CO_2$ emission scenarios, the Representative Concentration Pathways (RCP) 2.6, 4.5, 6.0 and 8.5. We also investigated the predictive uncertainty stemming from five individual algorithms and four $CO_2$ emission scenarios for better interpretation of SDM projections. Five individual algorithms were Generalized linear model (GLM), Generalized additive model (GAM), Multivariate adaptive regression splines (MARS), Generalized boosted model (GBM) and Random forest (RF). The results showed high variations of model performances among individual SDMs and the wide range of diverging predictions of future distributions of Korean fir in response to RCPs. The ensemble model presented the highest predictive accuracy (TSS = 0.97, AUC = 0.99) and predicted that the climate habitat suitability of Korean fir would increase under climate changes. Accordingly, the fir distribution could expand under future climate conditions. Increasing precipitation may account for increases in the distribution of Korean fir. Increasing precipitation compensates the negative effects of increasing temperature. However, the future distribution of Korean fir is also affected by other ecological processes, such as interactions with co-existing species, adaptation and dispersal limitation, and other environmental factors, such as extreme weather events and land-use changes. Therefore, we need further ecological research and to develop mechanistic and process-based distribution models for improving the predictive accuracy.

• Journal of the Korean Society of Food Culture
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• v.14 no.4
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• pp.271-287
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• 1999

A change in distribution structure affect a consumption structure which may result in considerable changes in lifestyle including food purchase. The purpose of this study was to investigate the effect of change of distribution structure on the indigenous fermented food purchase. The informations of this study were obtained from 407 housewives residing in Seoul and the capital area by using questionnaire during May to June, 1997 Their data were statistically analyzed based on frequency, mean, and $X^2-test$. The results were as follows; 1) The percentages of subjects buying ready made fermented food were 69.8% for Jotkals(salt-fermented fish products), 22.3% for Kochujang(fermented red pepper soybean paste), 21.6% for Janachis(pickled basic side dishes), 21% for Kanjang(Korean style soybean sauce), 17.1% for Toenjang(Korean style soybean paste), and 3% for Kimchi(seasoned and fermented vegetables). 2) With decreasing age, preparation ability of Kanjang, Janachis, and Kimchi. The subjects living close to the new distribution channel were higher in ready made fermented food than the others. 3) Compared to the subject living far from the new distribution channel, the subject living close to the new distribution channel was high in frequency of new distribution channel utilization for indigenous fermented food purchase but low in frequency of conventional market utilization. The younger in age, higher in educational level, and nuclear family, the higher the utilization of new distribution channel for indigenous fermented food purchase.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.3
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• pp.63-70
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• 2018

In this study, a simple probabilistic approach using equivalent coefficient of consolidation ($c_e$) was proposed to consider the spatial variability of coefficient of vertical consolidation ($c_v$), and the effect of the probability distribution of coefficient of consolidation on degree of consolidation in heterogeneous soil was investigated. The statistical characteristics of consolidation coefficient were estimated from 1,226 field data, and four probability distributions (Normal, Log-normal, Gamma, and Weibull) were applied to consider the effect of probability distribution. The random fields of coefficient of consolidation were generated based on Karhunen-Loeve expansion. Then, the equivalent coefficient of consolidation was calculated from the random field and used as the input value of consolidation analysis. As a result, the probabilistic analysis can be performed effectively by separating random field and numerical analysis, and probabilistic analysis was performed using a Latin hypercube Monte Carlo simulation. The results showed that the statistical properties of $c_e$ were changed by the probability distribution and spatial variability of $c_v$, and the probability distribution of $c_v$ has considerable effects on the probabilistic results. There was a large difference of failure probability depend on the probability distribution when the autocorrelation distance was small (i.e., highly heterogeneous soil). Therefore, the selection of a suitable probability distribution of $c_v$ is very important for reliable probabilistic analysis of consolidation.

• Journal of Distribution Science
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• v.15 no.4
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• pp.69-78
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• 2017

Purpose - The study was AI as exploratory study on artificial intelligence (AI) shopping information services, to explore the possibility of a new business of the distribution industry. For research, we compare to IBM of consumer awareness surveys an AI shopping information service for retailing channel and target goods group. Finally, we present to service scenario for distribution service using AI. Research design, data, and methodology - First, to identify possible the success of the information service shopping using AI, AI technology for the consumer is very important for the acceptance of judgement. Therefore, we explored the possibility of AI information service for business as a shopping. The experimental data were used to interpret the meaning of the relevant literature and the IBM Institute of Business Value (IBV) Report 2015. This research is based on the use of a technical acceptance model (TAM) to determine whether the consumer would adopt the 'AI shopping information service' technology. Step 1 of the process assumes that the consumer adopts AI technology. In step 2, consumers find their preference channels and goods targeted at them as per their preferences. Finally Step 3, we present scenario for 'AI shopping information service' based on the results of Step 1 and 2. Results - Consumers have expressed their high interests in the new shopping information services, especially the on/off line distribution channels can use shopping information to increase the efficiency in provision of goods. Digital channel (such as SNS, online shopping etc.) is especially high value goods such as cars, furniture, and home appliances by displaying it to an appropriate product group. Conclusions - The study reveals the potential for the use of new business models such as 'AI shopping information service' by the distribution industry. We present seven scenario related AI application refer from IBM suggestion, and the findings would enable the distribution industry to approach target consumers with their products, especially high value goods. 'Shopping advisor' is considered to the most effective. In order to apply to the other field of the distribution industry business, which utilizes AI technology, it should be accompanied by additional empirical data analysis should be undertaken.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.2
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• pp.9-18
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• 1986

For identification and apportionment of sources emitting particulate matters in environment, the multi-elemental characterization of size-density fractionated particulate matters was carried out. Eight types of samples were tested; soil, flyash released from burning of bunker-Coil, diesel oil, coal, and soft coal, urban road-way dust, urban dust fall, and airborne particulate matter. The fractions of particulate matters obtained by heavy liquid separation methos with a series of dichloromethane-bromoform were then analyzed using atomic absorption spectrophotometry for Ni, Cr, Cu, An, Fe, Al, and Mg. Each sample showed a different concentration profile as a function of density, and a number of useful conclusions concerning characterization of elemental distribution were obtained. From the density distributions of elements in soil, the maximum value was found for all elements in the density range of 2.2 $\sim 2.9g.cm^{-3}$, including the density of $SiO_2$. However, the distribution of metallic compounds with the density lower than $2.2g.cm^{-3}$ was prevalent in urban roadway dust, urban dust fall, and airborne particulate matter. And the density distribution curves of these urban dusts also have the higher distribution at the density of 2.2 - 2.9g.cm^{-3}$, including the density of wind-blown silica. This tendency generally was prevalent in the natural source elements, such as Al, Fe, Mn, and Mg. The maximum values were found in the density ranges of 1.3 $\sim 2.2g.cm^{-3}$ from the density distribution of elements in oil fired flyash. These distributions of anthropogenic source elements, such as Zn, Ni, Cu, and Cr were higher predominately than those of natural source elements. And the higher distribution was found in the density range of $2.2 \sim 2.9g.cm^{-3}$ from the density distribution of elements in coal and soft-coal fired flyash. These distributions showed similar patterns to soil. But anthropogenic source elements somewhat predominated at the density ranges of $1.3 \sim 2.2g.cm{-3} and 2.9g.cm^{-3}$ to soil. Therefore the higher distribution of anthropogenic source elements in the density ranges of $1.3 \sim 2.2g.cm^{-3} and 2.9g.cm^{-3}$ was considered as anthropogenic origin.

• Journal of Astronomy and Space Sciences
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• v.31 no.2
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• pp.149-157
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• 2014

As the prediction of geomagnetic storms is becoming an important and practical problem, conditions in the Earth's magnetosphere have been studied rigorously in terms of those in the interplanetary space. Another approach to space weather forecast is to deal with it as a probabilistic geomagnetic storm forecasting problem. In this study, we carry out detailed statistical analysis of solar wind parameters and geomagnetic indices examining the dependence of the distribution on the solar cycle and annual variations. Our main findings are as follows: (1) The distribution of parameters obtained via the superimposed epoch method follows the Gaussian distribution. (2) When solar activity is at its maximum the mean value of the distribution is shifted to the direction indicating the intense environment. Furthermore, the width of the distribution becomes wider at its maximum than at its minimum so that more extreme case can be expected. (3) The distribution of some certain heliospheric parameters is less sensitive to the phase of the solar cycle and annual variations. (4) The distribution of the eastward component of the interplanetary electric field BV and the solar wind driving function BV2, however, appears to be all dependent on the solar maximum/minimum, the descending/ascending phases of the solar cycle and the equinoxes/solstices. (5) The distribution of the AE index and the Dst index shares statistical features closely with BV and $BV^2$ compared with other heliospheric parameters. In this sense, BV and $BV^2$ are more robust proxies of the geomagnetic storm. We conclude by pointing out that our results allow us to step forward in providing the occurrence probability of geomagnetic storms for space weather and physical modeling.

• Journal of Distribution Science
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• v.16 no.10
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• pp.77-82
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• 2018

Purpose - This paper examines the relationship between corporate social responsibility and financial reporting quality. Corporate social responsibility is a way for firms to take responsibility for the social and environmental impacts of their business operations. Corporate social responsibility is a broad concept that can take various forms depending on the firm and industry. Through corporate social responsibility programs, firms can benefit society. At the same time, firms improve their reputations by increasing engagement in corporate social responsibility activities. However, corporate social responsibility activities are not directly related to profitability, especially for distribution firms. Research design, data, and methodology - 229 distribution & service firm-years between 2011 and 2016 are used for the main analysis. In Korea, Korean Economic Justice Institute evaluates the ethical performance of Korean firms, and the institute annually discloses the scores of top firms. This study uses the KEJI Index scores to measure firm-level corporate social responsibility activities. Discretionary accruals are used as a proxy for financial reporting quality. Discretionary accruals can be used opportunistically, and thus distort the information in earnings. We extract financial data from the KIS Value database. Results - We find that distribution & service firms' engagement in corporate social responsibilities is positively related to their financial reporting quality. First, there is a negative correlation between implementation of corporate social responsibility activities and discretionary accruals. In addition, we find that the coefficient of CSR is significantly negative, supporting our prediction. The result is significant at the 1% level. Conclusions - We examine the relationship between corporate social responsibility activities of distribution firms and their financial reporting quality while most prior studies examine the engagement in corporate social responsibility activities of manufacturing firms. The results of this study show that distribution & service firms engaging in corporate social responsibility activities are likely to maintain high-quality financial reporting.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.33-43
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• 2005

The girder wheel load distribution factors stated in the Korean Bridge Specification and AASHTO Standard Specifications do not account for the effect of skewness of plate girders, and very little research has been conducted on girder wheel load distribution factors. The purpose of the study is to propose load distribution factor formulas for skew plate girder bridges which comprise various parameters through structural analysis. To confirm the validity of finite element models used in this study analytic values are compared with the field test results. From the results it should be noted that span length is not such a dominant parameter compared with others. In view of better load distribution of interior girders, skew arranged cross beams or bracing are preferable, furthemore bracing system is more effective than cross beam system. By means of regression analysis on the basis of analytic results wheel load distribution factor formulas are proposed and compared with current codes.

• Journal of Korean Society of Forest Science
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• v.80 no.4
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• pp.420-426
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• 1991

This study was conducted to provide fundamental information to make rational management planning in eastern seacoast forest, mainly composed of black pine (Pinus Thunbergii), Kangweon Province. Diameter distribution was estimated by the method of Weibull distribution. The results were as fallows ; 1. Average diameter in the eastern seacoast forests of Kangweon Province was 10.3cm, and the average D. B. H, of 16 study sites ranged from 6.9 to 14.6cm. 2. Parameters of the Weibull distribution were estimated in each study sites and the estimated parameters of the all study forests were a=5, b=5.6997 and c=1.4079. 3. Tested by Kolmogorov-Smirnov method for the significant differences between actual and estimated diameter distribution, the result showed that estimated values were well fitted to the actual ones at 5% significance level.