• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.4
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• pp.567-576
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• 2017

In a performance-based design, the structural safety is estimated from pre- defined damage states and corresponding damage indices. Both damage states and damage indices are well defined for above-ground structures, but very limited studies have been performed on underground structures. In this study, we define the damage states and damage indices of a cut-and-cover box tunnel which is one of typical structures used in metro systems, under a seismic excitation from a series of inelastic frame analyses. Three damage states are defined in terms of the number of plastic hinges that develop within the structure. The damage index is defined as the ratio of the elastic moment to the yield moment. Through use of the proposed index, the inelastic behavior and failure mechanism of box tunnels can be simulated and predicted through elastic analysis. In addition, the damage indices are linked to free-field shear strains. Because the free-field shear strain can be easily calculated from a 1D site response analysis, the proposed method can be readily used in practice. Further studies are needed to determine the range of shear strains and associated uncertainties for various types of tunnels and site profiles. However, the inter-linked platform of damage state - damage index - shear wave velocity - shear strain provides a novel approach for estimating the inelastic response of tunnels, and can be widely used in practice for seismic designs.

• Journal of Food Hygiene and Safety
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• v.31 no.4
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• pp.278-285
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• 2016

This study used response surface methodology (RSM) in an effort to optimize the ultrasoundassisted extraction condition of Camellia sinensis L. and Artemisia argyi mixture in order to increase extraction yield in the extract. The effects of three independent variables, $X_1$ (Mixture ratio, 60-80%), $X_2$ (Ratio of water to raw material, 20~100 mL/g), and $X_3$ (Extraction time, 25-145 min), were investigated at three levels using Box-Behnken design (BBD) to obtain the highest extraction efficiency. Y (Extraction yield) was chosen as dependent variable. Our result showed that the coefficient of determination ($R^2$) of the model was 0.9747, with significant at the level of p < 0.002. Furthermore, the predicted values of each variable were similar to the actual values. The optimum extraction conditions were as follows: mixture ratio of 85.86%, ratio of water to raw material of 92.73 mL/g, and extraction time of 56.52 min. At these conditions, predicted extraction yield was 30.03%. The analysis of variance (ANOVA) indicated a high goodness of model fit and the success of the RSM method for optimizing extraction conditions of Camellia sinensis L. and Artemisia argyi mixture.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.107-115
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• 2013

The Old Town of Daejeon has significantly gone down due to population decrease and vacancy of buildings. To resolve these problems, it is necessary to develop revitalization measures with unique features, but it is also important to use historical and cultural resources from a certain point for the regeneration of local community. The Old Town of Daejeon has a number of industrial structures and architectural heritages that give character to the spaces, but most of them are being impoverished without any use although they have universal value. This study examined the standards to evaluate the importance and value of modern industrial heritages as historical resources that contributed to the development of local community and discussed case studies to review the value and use of industrial heritages that laid the foundation of Daejeon's development as a modern city to address the needs for urban regeneration through preservation and use of modern industrial heritages. Also, the limitations of administrative efforts were identified and the solutions were sought to address the needs to gather efforts with local government offices and the private sector. In conclusion, this study suggests an active and open policies to use cultural heritages through the use of modern industrial heritages for the revitalization of local communities based on the study of policies for the communication of urban users and community cultural spaces, preservation of landscapes including industrial heritages, and preservation in connection to social organizations and social companies, and that it is necessary to provide policies followed by efforts, i.e., to arbitrate the owners.

• The Korean Journal of Air & Space Law and Policy
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• v.32 no.2
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• pp.219-246
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• 2017

Nuclear issue is a good example showing globalization of the international regime. The history showed nuclear weapons may cause the extinction of human races when the first nuclear bombs fell down to Japan in August, 1945 and people became increasingly eager to achieve peace. Military buildup for national security is a matter of existence in the international society. However, disarmament or arms control to secure international peace and safety which is also the purpose of the Charter of the United Nations may be the most important task for us to realize peace of the mankind. Today, disarmament, together with amicable settlement of international conflicts and collective security system, is an important means to maintain and promote international peace and safety. It might be our permanent task to realize complete disarmament but, as the Preamble of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) expressed general and complete disarmament, the international society has clarified its effort for complete disarmament. Thus, taking a look into the international regime on the nuclear issue and progress related to the nuclear issue in North Korea, the study was intended to introduce the globalization of the nuclear issue, review the international effort for nuclear disarmament based on the concept of the 'common heritage of the mankind' and with respect to the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) and controls over nuclear weapons, and then evaluate the North Korean nuclear issue, which is in direct relation with South Korea and international laws, in terms of the space law and disarmament acts. The collective security system along with policies to prevent dissemination of nuclear weapons should also be emphasized and implemented to cope with the North Korean nuclear issue.

• Journal of the Korean GEO-environmental Society
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• v.19 no.11
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• pp.23-30
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• 2018

According to recent ground collapse occurrence, ground subsidence is increasing every year in downtown area, which is a social problem. The purpose of this study is to investigate the relationship between ground water level lowering and ground collapse through laboratory model experiments. After mixing 1:1 granite weathered soil with sand, sandy soil was formed as a relative density of 30%, 50%, and 80%. And then the changes of soil discharge with change of groundwater level were compared. The physical property of material of which particle distribution were well graded with maximu dry unit weight of $1.94kg/cm^3$ and internal friction angle of 37degrees. Ground water levels were measured at 10 cm, 20 cm, and 30 cm from the bottom. As a result, the experiment shows that the higher the groundwater level works the higher the discharge velocity and the magnitude of underground cavity also increases with elapsed time. Finally, the cumulative quantity of soil discharge occurred up to 30 kg at the elapsed time, 35 minutes. It was also confirmed that the range of ground collapse increased due to soil discharge with ground water level lowering.

• Korea journal of population studies
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• v.31 no.3
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• pp.107-130
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• 2008

The study of Korean diaspora has focused on migration, adaptation, and identity of overseas Koreans in China, the CIS, Japan, and the United States. However, the contemporary concept of a diaspora is a way of understanding migration, cultural difference, identity politics, and so on. Thus, this more broadly defined diaspora is used to mean a dispersion of people of a common national origin or of common beliefs living in exile. As of 2007, it is estimated that there are about 7 million Koreans living in 170 countries outside the Korean peninsula. Some have left Korea involuntarily and some others voluntarily. But most of them actively try to maintain their identity and culture as Koreans. With the large number of overseas Koreans, there has recently been the recognition of the importance of networking among overseas Koreans in the 21st century. The purpose of this paper is to emphasize the necessity of Korean Global Network of overseas Koreans. In doing so, this paper reviewed the case of Jewish and Chinese network. Then, this paper indicates the problems in the networking of overseas Koreans and suggests the policy implications for Korean Global Network. Above all, there should be changes in the government's policy towards overseas Koreans in the direction of organizing networks of overseas Koreans to coexist with the mother country. The government should adopt a policy to restore trust in overseas Koreans. It should take a pragmatic approach to the mutual interests in the socioeconomic relations instead of taking a political approach to overseas Koreans.

• Land and Housing Review
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• v.4 no.3
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• pp.259-270
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• 2013

This paper defined the concept of unsold land and diagnosed the cause of unsold land of LH business site. The results are showing as follows. First, unsold land is defined as land could not be sold until the completion of the project, and plan to sell the unsold land can be changed partially. Second, the status of unsold land in the 226 project sites were analyzed. $146km^2$ area corresponding to 74.8% of the total capital area($195km^2$) are unsold. By purpose, co-residential($38km^2$), industry($21km^2$), exclusive residential($16.4km^2$), commercial business($12.5km^2$), education($10.2km^2$) was larger in order. Third, value enhancement target project sites were selected and its symptoms and the cause of unsold land were analyzed. For the project site over average unsold rate, 6 sites located in province and 2 sites located in capital region were selected through collecting the practitioners and expert opinion. These 8 sites are characterized that sale of land for medium and large co-residential, urban support facilities, block-shaped house and attached house was inactive. Also, these sites commonly experienced economic fluctuations, changes in market demand, supply and demand mismatch, inflexible planning standards.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.137-147
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• 2014

The study aims at exploring motivation, rationale, and values in twitter users' retweet behavior. It proposes that diffusion of message is based on the complex interactional relationships among attributes of original message, user's rationale, and values. Based on a pilot study, we constructed a total of 34 questions asking message attributes, motivation, and values of retweeting. Then, twitter users participated in an online survey, in which they evaluate their own 5 retweet messages based on the constructed questions(5 messages ${\times}$ 34 questions = 170). Then, a factor analysis is done in order to see the dimensions of the concepts in retweet behavior; and understand how message attributes, motivations, and values are inter-related with each other. The main factors extracted were: (1) public fairness, (2) fun and playfulness, (3) communal help, (4) news and information, etc. Factor 2 and 4 show the traditional journalism characteristics; while factor 1 and 3 do alternative journalistic values. The latter may work as a rectifying factors for traditional journalism; however, backfiring mechanism for group polarization. In addition, (1) users' internal identities, (2) communal unity and (3) belongness were identified as rationales and values for retweet behavior.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.596-608
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• 2018

As urban infrastructure is aging, the possibility of accidents due to the failures or breakdowns of infrastructure increases. Especially, aging underground infrastructures like sewer pipes, waterworks, and subway have a potential to cause an urban ground sink. Urban ground sink is defined just as a local and erratic collapse occurred by underground cavity due to soil erosion or soil loss, which is separated from a sinkhole in soluble bedrock such as limestone. The conventional measurements such as differential settlement gauge, inclinometer or earth pressure gauge have a shortcoming just to provide point measurements with short coverage. Therefore, these methods are not adequate for monitoring of an erratic subsidence caused by underground cavity due to soil erosion or soil loss which occurring at unspecified time and location. Therefore, an alternative technology is required to detect a change of underground physical condition in real time. In this study, the feasibility of a novel magnetic resonance based monitoring method is investigated through laboratory tests, where the changes of path loss (S21) were measured under various testing conditions: media including air, water, and soil, resonant frequency, impedance, and distances between transmitter (TX) and receiver (RX). Theoretically, the transfer characteristic of magnetic field is known to be independent of the density of the medium. However, the results of the test showed the meaningful differences in the path loss (S21) under the different conditions of medium. And it is found that the reflection coefficient showed the more distinct differences over the testing conditions than the path loss. In particular, input reflection coefficient (S11) is more distinguishable than output reflection coefficient (S22).

• (The)Korea Educational Review
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• v.24 no.4
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• pp.247-286
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• 2018

The study aims to analyze the research trends according to 'characteristics of researchers' in the research papers published in "The Journal of Educational Administration" between last 10 years(2009 to 2018 first half). The study results are as follow. First, in terms of the researcher, more research was done by 'joint' researchers than a 'single' researcher. In addition, the number of studies in which the first author was male was higher than in women. Also, collaborative research between 'professors' and 'graduate students' was actively done. Second, the number of studies to develop and verify theories(or models) has increased. Third, in terms of research methods, more studies tend to utilize 'quantitative research' using advanced statistics and 'qualitative research' through interviews and observations to describe and explain Korea's educational administration phenomenon. Fourth, researchers showed high interest in 'School organization and management;', 'Higher education', 'Education policy and planning'. Fifth, according to each research area, there were some differences in the characteristics of the researchers who conducted the research, the nature of the research, and the research methods used mainly. Based on the results of this study, this study suggested the future trends of educational administration research in the era of the fourth industrial revolution.