• Journal of the Korean Society for information Management
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• v.27 no.2
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• pp.37-60
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• 2010

The purpose of this study is to investigate image search query reformulation patterns in relation to image attribute categories. A total of 592 sessions and 2,445 queries from the Excite Web search engine log data were analyzed by utilizing Batley's visual information types and two facets and seven sub-facets of query reformulation patterns. The results of this study are organized with two folds: query reformulation and categorical transition. As the most dominant categories of queries are specific and general/nameable, this tendency stays over various search stages. From the perspective of reformulation patterns, while the Parallel movement is the most dominant, there are slight differences depending on initial or preceding query categories. In examining categorical transitions, it was found that 60-80% of search queries were reformulated within the same categories of image attributes. These findings may be applied to practice and implementation of image retrieval systems in terms of assisting users' query term selection and effective thesauri development.

• STI Policy Review
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• v.7 no.1
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• pp.1-16
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• 2016

Technology supply has been the main thrust of the Korean government's science & technology policy, focusing on the development and acquisition of new technology in line with the catching-up strategy of economic growth and industrial development. However, new social or societal problems have become major government policy issues, heralding new innovation policy aimed to address them. Such new policy initiatives for social problem-solving present a niche where the existing system of government innovation policy process is challenged, including such processes as goal-setting, planning, implementation, project management, and evaluation. The rigidity of the existing institution of government innovation policy, however, still shapes the content and progression of innovation policy for social problem-solving. This study reviews Korean innovation policy for social problem-solving as a policy niche, and aims to clarify its challenges and opportunities. It uses a system transition framework to explain the emergence and evolution of the innovation policy niche in Korea. The main research question is to what extent and in what aspect the existing innovation policy regime shaped innovation policy for social problem-solving. The study examines the inertia of the current paradigm of innovation policies and R&D programs, and sheds light on the search for a distinctive identity for innovation policies that tackles social problems.

• Proceedings of the KIEE Conference
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• summer
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• pp.120-122
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• 2004

This paper analyse impacts of Community Energy System (CES) on the grid during transition periods for integrating of the CES and the grid. In the near future, CES might be one of major energy supply structures. The basic concept of CES is that it supplies electrical and thermal energy to the local customer loads through the islanded power network separated from the grid. Therefore, the interconnection with the grid occurs only when the energy supply from the CES generators does not meet the demand of the local load. For avoiding impacting the grid during the transition operation modes of CES, it is necessary to thoroughly analyse the influences on the grid during those periods. In order to show them, in this paper, we model the CES with 2.34 WVA DG and simulate the impacts on the grid due to interconnection of CES The simulation results show that, in order to reduce bad influences of CES on the grid, CES need the efficient load management and generation control schemes during the transition periods.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.225-235
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• 2010

There are many types of the geometric transitions such as dent, bulge, protrusion, expansion, etc, on the inner and outer surfaces of heat exchanger tubes, steam generator tubes, and condenser tubes of nuclear power plants. Such geometric transition causes a local residual stress in heat exchanger tubes and acts as a structural factor accelerating the evolution of defects, in particular stress corrosion cracks. In the conventional eddy current test methods, the bobbin coil profilometry can provide 2-dimensional geometric information on the variation of the average inner diameter along the tube length, but the 3-dimensional distribution and the quantitative size of a local geometric transition existing in the tube cannot be measured. In this paper, a new eddy current probe, developed for the 3-dimensional profile measurement, is introduced and its superior performance is compared with that from the conventional bobbin coil profilometry for the various types of geometric transition. Also, the accuracy of the probe for the quantitative profile measurement is verified by comparing the results with that from the laser profilometry. It is expected that the new eddy current probe and techniques can be effectively used for an optimization of the tube expansion process, and the management of tubes with geometric transitions in service.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.93-99
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• 2021

The government has proposed a mission to enhance intelligent power networks, decrease coal-fired generation, expand distributed energy resources, and promote energy prosumer into the distribution network in Korea. Installation cost of facility expansion to guaranteed interconnection with small distributed energy resources increases dramatically on KEPCO's distribution sector. And it is hard to withdraw in time. In addition, there are explicit research is required to meet the reliability on grid corresponding to the increase of distributed power. Infrastructure support for accommodating energy prosumer is also needed. Therefore, KEPCO is pushing transition to DSO by expanding distribution management scope and changing its roles. In addition, KEPCO is proactively preparing for integrated operation between distribution network and existing distributed power which is accommodated passively. KEPCO is also trying to accept multiple network users, e.g. building platforms, to manage a data and promote new markets. In the long term, transition to DSO will achieve saving investment costs for accommodating distributed sources and maintaining stable electrical quality. And it will be possible to create new business model using the platform to secure revenue.

• Human Ecology Research
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• v.61 no.3
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• pp.335-348
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• 2023

The purpose of this study was to identify: (a) the latent profiles of the difficulties associated with the schoolto-work transition (decline in confidence, mood swings, family disagreements, the burdens of familial expectations, economic hardship, and a lack of support) made by university students, (b) predictors (gender, age, grade, university location, co-residence with parents on weekdays, monthly household income, and parental educational attainment) of these profiles, and (c) how the profiles were associated with mental wellbeing. The participants of this study were 311 senior or above students (164 males and 147 females) under the age of 29, who were unmarried and preparing for employment. The findings of this study were as follows. First, the latent profile analysis revealed three distinct profiles: the "low overall difficulties" type (25.4%), the "moderate overall difficulties" type (49.9%), and the "high overall difficulties" type (24.7%). Second, the factors that predicted each profile included gender, age, co-residence with parents on weekdays, monthly household income, and parental educational attainment. Third, the "low overall difficulties" type demonstrated the highest level of mental well-being (emotional, social, and psychological well-being). This study was significant for examining the latent profiles of the difficulties associated with the school-to-work transition made by university students preparing for employment, while also exploring their mental well-being. Based on the results of this study, practical implications, limitations, and suggestions for further study were discussed.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.3
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• pp.25-31
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• 2016

Mechanical properties of Y2O3-containing tetragonal ZrO2 polycrystals(Y-TZP) were investigated. Several additives were used to modify the hardness and fracture toughness of Y-TZP. The effects of these individual additives were discussed and their interactions were also analysed. Each additive, such as CoO, Fe2O3, MnO2 was found to deteriorate the mechanical properties of Y-TZP when it was used singly. But the fracture toughness of Y-TZP was significantly improved when these additives and Al2O3 were added in combination at a certain ratio. The addition of CoO, Fe2O3 and MnO2 into Y-TZP resulted in the more complex behavior of fracture toughness and hardness. The specimen with 1.5 wt%-Fe2O3, 3.0 wt% -Al2O3 and 1.5 wt%-CoO showed the monoclinic to tetragonal phase ratio of 18% and the highest toughness of $10.8MPa{\cdot}m1/2$ with Vickers hardness of 1201 kgf/mm2. However, the toughness decreased as the ratio increased and macrocracks developed beyond the ratio of 25%. Sample No. 16 is improved high Physical and Mechanical Properties.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.4
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• pp.99-115
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• 2005

For an analysis of the performance of a computer system, the minimum cycle time method has been widely used. The minimum cycle time method is a mathematical technique with which we can find the minimum duration time needed to fire all the transitions at least once and coming back to the Initial marking in a timed net. A timed net is a modified version of a Petri net where a transition is associated with a delay time. In the real world, an event is associated with a probability of occurrence. However, a timed net is not equipped with any facility of specifying probability of event occurrence. Therefore, the minimum cycle time method applied on a timed net can easily overlook probabilities of occurrences of events and yield a wrong result. We are proposing 'Timed Net with Probabilities of Choices' where a transition can be associated with both delay time and a probability of occurrence. We also introduce an algorithm for minimum cycle time analysis on a 'Timed Net with Probabilities of Choices'. As an example of application, we are performing an analysis of the location based service system using 'Timed Net with Probabilities of Choices'.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.1
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• pp.201-216
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• 2013

Diffusion is a basic mathematical tool for modern financial engineering. The theory of the estimation methods for diffusion models is an important topic of the financial engineering. Many researches have been tried to apply the likelihood estimation method for estimating diffusion models. However, the likelihood estimation method for diffusion is complicated and needs much amount of computing. In this paper we develop the estimation methods which are simple enough to be compared to the Euler approximation method, and efficient enough statistically to be compared to the likelihood estimation method. We devise pseudo-likelihood and propose the maximum pseudo-likelihood estimation methods. The pseudo-likelihoods are obtained by approximating the transition density with normal distributions. The means and the variances of the distributions are obtained from the delta expansion suggested by Lee, Song and Lee (2012). We compare the newly suggested estimators with other existing estimators by simulation study. From the simulation study we find the maximum pseudo-likelihood estimator has very similar properties with the maximum likelihood estimator. Also the maximum pseudo-likelihood estimator is easy to apply to general diffusion models, and can be obtained by simple numerical steps.

• Korean Management Science Review
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• v.32 no.2
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• pp.37-50
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• 2015

The number of contracts for bundling services in a domestic telecommunication market records 1.3 miilion as of the first half year in 2007, and steadily increased to 8.97 million in 2010, to 12.76 million in 2013. In 2014, 70.4% of telecommunication service consumers are found to subscribe to bundling service. Bundling services provide consumers with benefits such as price discount, convenience, increase ARPU. However, a market dominant player in a specific market may transfer its market power to another market by selling bundling services. SSNIP has been adopted to provide a market definition. However, SSNIP is not suitable to measure the effect of market power transition through bundling services because SSNIP cannot measure the effect of changeover sales of bundling services. Thus, in this study, we have investigated the effect of market power transition through bundling services reflecting market power effect and quality upgrade using Gross Upward Market Power Pressure Index metho and reviewed UPP and derivative UPP models.