• Journal of Korea Water Resources Association
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• v.47 no.10
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• pp.921-934
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• 2014

The purpose of the study is to derive a long term reservoir operation method that is easy to understand and apply to practical use for dam operators. The zone based operation rule is a simple method to make operation decisions by criteria corresponding to storage zones. The reservoir storage levels dividing a reservoir, however, must be determined by some methods. We developed a reservoir operation model based on the zone based operation rule and the shuffled complex evolution algorithm (SCE-UA) was used to determine storage levels for zone division. The model was applied to Angat Dam in the Philippines that has trouble in water supply due to imbalance between supply and demand. We derived a zone based operation rule for Angat Dam and applied it to the reservoir simulation of Angat Dam using the historical inflow. The simulation results showed water supply deficit and power generation were improved by 34.5% and 21.2%, respectively, when compared with the historical records. The current study results may be used to derive a long term reservoir operation rule.

• The Journal of the Korea Contents Association
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• v.17 no.7
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• pp.283-293
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• 2017

This study analyzed the actual conditions of use of public sports facilities and characteristics of the users of the facilities through surveys and measured the spatial imbalance of the public sports facilities currently supplied by using gravity potential model. This study also suggests evaluation criteria that may be considered for efficient location selection by examining the change of accessibility to the facilities that meet the needs of users in the future. As the results of the questionnaire survey, unlike current usage, the users hoped for badminton, weight training and swimming. And we could confirm the demand for the expansion of the multi - purpose indoor gym which can carry out such activities in the areas. As the result of the analysis on the difference in accessibility of the public sports facility, there were some large variations in the regions. It was found that a balanced supply of facilities was needed in terms of equity. In particular, when analyzing by considering the population estimates of 2025, It is analyzed that the accessibility will be reduced to about 60% compared to that of 2015. In addition, it is evaluated as the best alternative in terms of overall efficiency that the location of the facilities should be in Munsan area where population growth is expected in the future.

• The Korean Journal of Food And Nutrition
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• v.26 no.4
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• pp.620-632
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• 2013

The purpose of this study is to analyze Hanwoo usage in school foodservices and to develop menus of lean cut Hanwoo. As a result, satisfaction of students, parents and teachers all increased regardless of school type after using Hanwoo. The high price compared to other meats (3.98) was the biggest difficulty for using lean cut Hanwoo followed by reduced taste preferences (2.84), lack of parent awareness (2.67) and lack of appropriate cooking facilities (2.13). According to the survey on how to increase the usage of lean cut Hanwoo, improvement of meat tenderness (3.80), development of various sauces (3.74) and development of seasoning for existing menu (3.61) were identified as major necessities. This analysis of Hanwoo utilization in school foodservice was used to develop menus of lean cut Hanwoo. The menu was particularly developed to overcome the supply-demand imbalance of different cuts. For the menu development process, potential Hanwoo utilization in school foodservice, cooking method, and diverse taste were considered. In order to evaluate the applicability in school foodservice, JARS was used and the final eight menus were selected. For the selected menu, a nutrition analysis was conducted. Further, systematic recipes with a mixing ratio;product process description and a simplified product process were also developed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.88-93
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• 2011

To resolve the problem which is demand and supply imbalance of fine aggregate by the shortage of natural fine aggregate and the environment regulations, the studies for the application of recycled fine aggregate made from waste concrete have been recently carried out. The objective of this study is to shed light on the mechanical properties and durability performance of concrete using recycle fine aggregate with various water to cement ratios and unit water contents. And it is intend to propose the fundamental data for structural application of recycled concrete. In particular, the effects according to the variations of water to cement ratios and unit water contents in recycled concrete with recycled fine aggregate replacement of 100 percent are discussed by the test results, such as air content, slump, time of set, compressive strength, tensile strength, carbonation, chloride penetration.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.5
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• pp.248-254
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• 2001

The traction power demand highly varies with time and train positions and the traction load is a large-capacity current at single phase converted from 3-phase power system. Subsequently, each phase current converted from 3-phase power system cannot be maintained in balance any longer and thus the traction load can bring about imbalance in three-phase voltage. Therefore, the exact assessment of voltage unbalance must be carried out preferentially as well as load forecast at stages of designing and planning for electric railway system. The evaluation of unbalance voltage in areas, such as electric railway depots should be a prerequisite with more accuracy. The conventional researches on voltage unbalance have dealt with connection schemes of the transformers used in ac AT-fed electric railroads system and induced formulas to briefly evaluate voltage unbalance in the system(3). These formulas are still being used widely due to their easy applicabilities on voltage unbalance evaluation. Meanwhile, they don't take into account detailed characteristics of ac AT-fed electric railroads system, being founded on some assumptions. Accordingly. accuracy still remains in question. This paper proposes a new method to more effectively estimate voltage unbalance index. In this method, numerous diverted circuits in electric railway depots are categorized in three components and each component is defined as a two-port network model. The equivalent circuit for the entire power supply system is also described into a two-port network model by making parallel and/or series connections of these components. Efficiency and accuracy in voltage unbalance calculation as well can be promoted by simplifying the circuits into two-port network models.

• Journal of Powder Materials
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• v.26 no.2
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• pp.146-155
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• 2019

Rare earth magnets are the strongest type of permanent magnets and are integral to the high tech industry, particularly in clean energies, such as electric vehicle motors and wind turbine generators. However, the cost of rare earth materials and the imbalance in supply and demand still remain big problems to solve for permanent magnet related industries. Thus, a magnet with abundant elements and moderate magnetic performance is required to replace rare-earth magnets. Recently, $a^{{\prime}{\prime}}-Fe_{16}N_2$ has attracted considerable attention as a promising candidate for next-generation non-rare-earth permanent magnets due to its gigantic magnetization (3.23 T). Also, metastable $a^{{\prime}{\prime}}-Fe_{16}N_2$ exhibits high tetragonality (c/a = 1.1) by interstitial introduction of N atoms, leading to a high magnetocrystalline anisotropy constant ($K_1=1.0MJ/m^3$). In addition, Fe has a large amount of reserves on the Earth compared to other magnetic materials, leading to low cost of raw materials and manufacturing for industrial production. In this paper, we review the synthetic methods of metastable $a^{{\prime}{\prime}}-Fe_{16}N_2$ with film, powder and bulk form and discuss the approaches to enhance magnetocrystalline anisotropy of $a^{{\prime}{\prime}}-Fe_{16}N_2$. Future research prospects are also offered with patent trends observed thus far.

• International Journal of Computer Science & Network Security
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• v.21 no.5
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• pp.160-167
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• 2021

The authors of the article investigate the impact of digitalization on the forms change of employment and the labor market in the modern conditions. It is substantiated that digitalization processes directly affect the change of forms of employment and the range of occupations in the labor market, as well as the change of jobs. The positive and negative consequences of changing forms of employment for the economy in the process of digital transformation are analyzed, which include: reduction of personnel costs by employers; dissemination of non-standard, informal employment (electronic freelance, electronic outsourcing, start-employment); enabling employees to manage their working hours; increasing unemployment and imbalance of supply and demand in the labor market; reduction of productivity of enterprises, as a result of reduced productivity of workers with non-standard forms of employment, or with a negative indirect impact on productivity. A model for managing the process of digitalization in the labor market of Ukraine under different scenarios of their implementation, namely evolutionary and forced is devoted. To recognize the possible change in the level of employment in connection with the implementation of the forced scenario of digitalization in Ukraine, a model for estimating probable changes in the labor market is proposed. The directions of development of the state strategy of prevention of risks of reduction of number of workplaces in the course of digitalization are outlined.

• The Journal of the Korea Contents Association
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• v.12 no.4
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• pp.86-94
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• 2012

With enforcement of five-day workweek system, leisure time for family has increased. However, there is imbalance between demand and supply of leisure because of the absence of proper way for spending leisure time with family. On the other hand, TV, which has been playing an important role as a media for family, shows new possibility of interaction with advent of Smart TV. With this tendency, now it could be an appropriate time for researching the healthy way to spend leisure time on weekend with family. Therefore this paper aims to propose a family farming contents called 'Our Farm', which links on-line and off-line. To firm up necessity and appropriateness of this paper, I analyzed existing thesis and games for family and did FGI(Focus Group Interview) with a family. In this research, I proposed the picture UI based on results of investigation.

• Journal of Digital Convergence
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• v.17 no.5
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• pp.327-332
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• 2019

The purpose of this study is to derive the differentiation and improvement measures of Kakao T through a usability evaluation centered on the service. In-depth interviews were conducted by first identifying the status of the mobility O2O service and reconfiguring the usability principles of the Honeycomb model, focusing on the functions and interfaces. First, there are problems driven from the imbalance in supply and demand as a mobility service, but it is likely to be improved through the addition of future features, carpooling. Second, problems were elicited for not recognizing the need for incorporated functions of Kakao T in the presence of existing functional-specific applications. Improvements derived based on this study are expected to help increase the convenience of users of mobility O2O services.

• Journal of Digital Convergence
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• v.16 no.9
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• pp.359-364
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• 2018

The purpose of this study is to investigate the phenomenon of users' experience of O2O transportation service - focus on the Kakao taxi. As a research method, first case study investigated characteristics of taxi app service in Korea and overseas O2O transportation service. Secondly, we conducted an in - depth interview with eight Kakao taxi users to understand the experience of using the taxi. As a result, we were able to derive two points that needed improvement. Firstly, the imbalance between supply and demand should be improved. Secondly, users should not be disadvantaged by the location disclosure. It is significant that this study suggests ways to improve domestic O2O transportation service through a taxi. It is expected that the follow up study will help improve the domestic O2O transportation service and improve the user experience.