• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.85.1-85.1
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• 2019

Accurate estimation of the masses, the ages, and the chemical abundances of host stars is crucial to understand physical characteristics of exo-planetary systems. In this study, we investigate physical dimensions of 94 planet-hosting stars based on spectroscopic observation and stellar evolutionary computation, From the high resolution echelle spectroscopy of the BOES observation, we have analysed metallicities and alpha-element enhancements of host stars. By combining recent spectro-photometric observations, stellar parameters are calibrated within the frame work of the standard stellar theory. In general, the minimum chi-square estimation can be strongly biased in cases that stellar properties rapidly changes after the terminal age main-sequence. Instead, we adopt a Bayesian statistics considering a priori distribution of stellar parameters during the rapid evolutionary phases. we determine a reliable set of stellar parameters between theoretical model grids. To overcome this statistical bias, (1) we adopt a Bayesian statistics considering a priori distribution of stellar parameters during the rapid evolutionary phases and (2) we construct the fine model grid that covers mass range ($0.2{\sim}3.0M_{\odot}$) with the mass step ${\Delta}M=0.01M_{\odot}$, metallicities Z = 0.0001 ~ 0.04, and the helium and the alpha-element enhancement. In this presentation, we introduce our calibration scheme for several hosting stars.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.239-249
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• 2019

Recently, the Korean government has implemented a policy to expand renewable energy sources. Large-scale PV systems are being actively interconnected with the distribution system. On the other hand, when a large-scale PV system is installed and operated, the customer voltages could violate the allowable voltage limit due to reverse power flow of the PV system. To overcome these problems, an enhancement method for hosting the capacity of the PV system in a distribution system is being actively conducted. Therefore, to improve the hosting capacity of the PV system, this paper proposes a model of a reconfiguration of the distribution system, which is composed of three sections and three connections based on PSCAD/EMTDC S/W, and proposes an evaluation algorithm for the feeder reconfiguration to maximize an adaption of the PV system. In addition, this paper presents the optimal method of the feeder reconfiguration section to evaluate the maximum capacity of the PV system to keep customer voltages within the allowable voltage limits based on various operation scenarios, such as the capacity of a PV system and section of feeder reconfiguration. From the simulation results based on the PSCAD/EMTDC modeling and evaluation algorithm, it was confirmed that they are a useful and practical tool to enhance hosting the capacity of a PV system in a distribution system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.809-815
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• 2018

Distributed generations (DGs) using renewable energy resources in power systems have been widely integrated, and many of these DGs have intermittency. DGs can significantly affect the overall voltage profile of the system through the reactive power control for a voltage support. Therefore, in the planning stage of the optimal operation and dispatch of voltage regulation devices, DGs' hosting capacity with the reactive power control scheme should be considered. In this paper, we model the IEEE 34-bus test feeder, including all essential equipment. An optimization method is utilized to determine the optimal siting and operation of the voltage regulation devices in the presence of DGs with reactive power control scheme. Finally, we compare the optimal results of the each case to analyze the relationship among the hosting capacity of the DGs and voltage regulation devices operation.

• Review of Korean Society for Internet Information
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• v.14 no.3
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• pp.58-67
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• 2013

An essential prerequisite for negotiating governance of 'internet,' a world of 'end to end' nature, is to guarantee end-users' participation. Internet Governance Forum (IGF), the outcome of World Summit on the Information Society(WSIS) Tunis Agenda, has played an important role as a representative mulitistakeholder - based governance model, which puts emphasis on wide range participation of stakeholders. Notwithstanding multistakeholderism materialized in IGF has been challenged, IGF itself is a unique place for participation to broad internet governance discourse, as all voices get hearing grounded on openness, inclusion, and transparency, quite distinct from the multilateral negotiation based model such as 'Conference on Cyberspace.' Therefore civil society which represents end-users' interest, as a crucial stakeholder of internet governance, should establish more strategic and coordinated approach to IGF itself as well as reformation discourse of internet governance. In this regard, civil society groups of Korea, began with hosting workshops and Open Forum at the 2013 IGF in Bali, Indonesia. This report also describes the detailed activities of Korean civil society group in 2013 IGF.

• Journal of the Korean Society for Library and Information Science
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• v.47 no.4
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• pp.79-102
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• 2013

This study examined the current state of digital libraries in Korean cyber universities and suggested recommendations for improvements. The study conducted a survey and face-to-face interviews with people in charge of managing cyber university digital libraries, and analyzed library Web sites as well as library holdings and budget information available from the university information disclosure. The examples of cyber university digital libraries in other countries were also analyzed. Based on the findings, the study developed guidelines and policies for improving cyber university digital libraries and suggested a hosting-based digital library system. The findings of this study is expected to contribute to enhancing the quality of education in cyber universities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.1-12
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• 2021

Technologies for an MVDC(medium voltage direct current) distribution system are being considered as an effective alternative to overcome the interconnection delay issues of PV systems. However, the implementation of a DC distribution system might lead to economic problems because of the development of DC devices. Therefore, this paper deals with the scale of a PV plant based on its capacity and proposes hosting-capacity models for PV systems to establish a network to evaluate the feasibility of an MVDC distribution system. The proposed models can be classified as AC and DC distribution systems by the power-supply method. PV systems with hundreds of MW, dozens of MW, and a few MW can be categorized as large-scale, medium-scale, and small-scale models, respectively. This paper also performed modeling for an economic evaluation of MVDC distribution system by considering both the cost of AC and DC network construction, converter replacement, operation, etc. The profit was composed of the SMP and REC rate of a PV plant. A simulation for economic evaluation was done for the MVDC distribution system using the present worth and equal-principal costs repayment method. The results confirmed that the proposed model is a useful tool to evaluate economic issues of a DC distribution system.

• Smart Structures and Systems
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• v.12 no.5
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• pp.501-521
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• 2013

This paper is concerned with static and dynamic shape control of a laminated Bernoulli-Euler beam hosting a uniformly distributed array of resistively interconnected piezoelectric patches. We present an analytical one-dimensional model for a laminated piezoelectric beam with material discontinuities within the framework of Bernoulli-Euler and extent the model by a network of resistors which are connected to several piezoelectric patch actuators. The voltage of only one piezoelectric patch is prescribed: we answer the question how to design the interconnected resistive electric network in order to annihilate lateral vibrations of a cantilever. As a practical example, a cantilever with eight patch actuators under the influence of a tip-force is studied. It is found that the deflection at eight arbitrary points along the beam axis may be controlled independently, if the local action of the piezoelectric patches is equal in magnitude, but opposite in sign, to the external load. This is achieved by the proper design of the resistive network and a suitable choice of the input voltage signal. The validity of our method is exact in the static case for a Bernoulli-Euler beam, but it also gives satisfactory results at higher frequencies and for transient excitations. As long as a certain non-dimensional parameter, involving the number of the piezoelectric patches, the sum of the resistances in the electric network and the excitation frequency, is small, the proposed shape control method is approximately fulfilled for dynamic load excitations. We evaluate the feasibility of the proposed shape control method with a more refined model, by comparing the results of our one-dimensional calculations based on the extended Bernoulli-Euler equations to three-dimensional electromechanically coupled finite element results in ANSYS 12.0. The results with the simple Bernoulli-Euler model agree well with the three-dimensional finite element results.

• Journal of Leisure Studies
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• v.6 no.3
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• pp.39-56
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• 2009

With the main player of international competition being changed from country to region/city, city competitiveness is emerging as driving forces of industrial and national competitiveness and organizations formed on a city level are regarded as the main unit of competition among nations. This paper's goal is to research upon the city competitiveness with an emphasis on the analytical tool applying IPS Model of city competitiveness to 75 Korean cities and to map out the strategies to enhance the Chuncheon city's competitiveness based on the results of the evaluation on Chuncheon city's current and future competitiveness with focus on the impact of the city's hosting World Leisure Congress and World Leisure Games in 2010. By discussing city's future competitiveness as well as its current strength at the same time, the more comprehensive perspective required in reinforcing city competitiveness is proposed in this paper and issues related to a city's context and policy can be evaluated and their solutions can be sought after. The study can also contribute to the establishment of city's development policies and detect sustainable growth power for individual cities.

• Cartoon and Animation Studies
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• s.46
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• pp.129-150
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• 2017

With the change in educational environment of cartoon creation and diversification of webtoon platforms, various ways of engaging webtoon authors have been suggested. Under this situation, Korea Manhwa Contents Agency(KOMACON) and Korea Creative Content Agency(KOCCA) provide support to webtoon authors directly and indirectly to nurture professional webtoon talents. Contents creative human resource joint project being carried out by KOCCA is mainly to nurture and support contents experts by developing their creativity through tight training between mentors and mentees, creating job opportunities, building the support system for creative activities, and supporting commercialization during the project. Undergoing the process of recruitment and selection, the participants of this project are educated, trained and developed according to education programs provided by the hosting agency, and this project has a model to compensate for creative activities for a ceratin period of time. However, there has been a problem that it is difficult to constantly keep and manage webtoon talents who are cultivated by human resource management of less than one-year project. This study analyzed creative human resource joint project which is a human resource development model, using human recourse theory and suggested a strategic human resource model based on webtoon authors' human resource model development.