• Smart Structures and Systems
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• v.14 no.2
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• pp.209-224
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• 2014

With more and more built long-term structural health monitoring (SHM) systems, it has been considered to apply monitored data to learn the reliability of bridges. In this paper, based on a long-term SHM system, especially in which the sensors were embedded from the beginning of the construction of the bridge, a method to calculate the localized reliability around an embedded sensor is recommended and implemented. In the reliability analysis, the probability distribution of loading can be the statistics of stress transferred from the monitored strain which covered the effects of both the live and dead loads directly, and it means that the mean value and deviation of loads are fully derived from the monitored data. The probability distribution of resistance may be the statistics of strength of the material of the bridge accordingly. With five years' monitored strains, the localized reliabilities around the monitoring sensors of a bridge were computed by the method. Further, the monitored stresses are classified into two time segments in one year period to count the loading probability distribution according to the local climate conditions, which helps us to learn the reliability in different time segments and their evolvement trends. The results show that reliabilities and their evolvement trends in different parts of the bridge are different though they are all reliable yet. The method recommended in this paper is feasible to learn the localized reliabilities revealed from monitored data of a long-term SHM system of bridges, which would help bridge engineers and managers to decide a bridge inspection or maintenance strategy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.699-711
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• 2011

This study is to perform several major analyses to find any differences in the leverage between the pre- and post-period of the currency crisis. Moreover, another aspect is to investigate a financial aspect which has received relatively little attention to the firms and/or industries in the emerging capital markets in comparison to those in the advanced markets. The purpose of this empirical study is to confirm whether or not, it is myth or reality that Korean business conglomerate, chaebol, firms with subsidized financing from government-owned domestic financial institutions in the pre-financial turmoil, may still maintain their higher leverage, even after the crisis. It was found that firms belonging to the chaebol in Korea maintained higher average book-value and market-value based debt ratios, relative to their counterparts not belonging to the chaebol across all of the tested models. There were positive relationships of IND3(=the chemical industry) and Ind5(=the construction industry) to the book-value leverage. This study identified that there were no differences in the explanatory variables included, between the tested models (that is, without and with including the present value of an operating lease) related to each debt ratio. Since the Korean government continue to improve the corporate governance of the domestic firms in terms of accounting transparency and corporate ownership, it would be more efficient, if utilizing this "new" ratio considering an operating lease as an effective measurement of the level of leverage. In terms of the capital structure, it may also be possible for foreign firms to utilize and benefit from the results obtained in this study when operating their new businesses in Korea, given the economic circumstances such as the ongoing progress of the Korea-America FTA or the Korea-China FTA.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.19-26
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• 2017

Concrete is a construction material with porous media and corroded steel inside affects negatively to durability and structural safety. This study aims a derivation of quantitative relationship between measured HCP (Half Cell Potential) and corrosion amount considering cover depth and W/C (water to cement) ratio. For the work, cement mortar specimens with 3 different W/C ratios and 4 different cover depths are prepared, HCPs are measured with 3 different corrosion level. HCP measurement significantly increases in the saturated condition and linear relationship is observed between corrosion level and acceleration period. With increasing corrosion level and W/C ratio, and decreasing cover depth, HCP measurement increases. Considering total corrosion level and HCP measurements, relatively low COV(Coefficient of Variation) of 0.67 is evaluated through multi-linear regression analysis, however higher COVs over 0.90 can be obtained considering level of HCP measurement. In the room condition, corrosion level can be evaluated through measured HCP in the given conditions of cover depth, W/C ratio. diameter of steel inside.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.4
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• pp.44-51
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• 2004

This study was to investigate and identify the trends and the direction of the researches related to the rooftop greening by analyzing the content of the studies published in Korea during the past two decades. Internet search was to collect data for this study, and the articles reviewed are limited to research journals, theses, and doctoral dissertations. The collected articles were then examined for content analysis and classified into several categories according to year, topic, and types of journals. The results showed that the total number of articles published in Korea for the period 1984-2004 was 97. While there was only one article in 1984, the number of articles has increased to 16 in 2000, 20 in 2003, and 16 in 2004 now. According to the analysis of the 97 data, there were 25 master's theses and 3 doctoral dissertations and 69 articles published in journals. Articles about rooftop greening were published most frequently in the Korea Institute of Landscape Architecture(11 articles), followed by Journal of Architectural Institute of Korea(8 articles) and Journal of Korea Society for Environment Restoration(7 articles).The studies regarding the rooftop greening has increased in number since the Ministry of Construction and Transportation made it possible to 10-15 cm shallow depth of soil in rooftop greening in 2000, which was above 100 cm before 2000. The articles examined are classified into four areas of research according to topic. The number of articles in each area is as follows : 57 articles in the field of the technology, 17 in the study of the plan and system, 10 in the case study, and 12 in the plant study, Particularly, the studies concerning technology are subdivided into the five areas and the number of each area is as follows : 25 studies for the plant base, 15 for design plan, 13 for the efficacy of the rooftop greening, 3 for the managing program, and 1 for the relation with buildings. Over the years, the studies for the rooftop greening have increased in number since these studies have made a positive effect on the improvement of the urban ecosystem and on the environment of the city lacking greens. However, the majority of research are for plant and planting base and those researches are not enough to make some effects on the improvement of the environment, it seems necessary to provide some system applicable to the field or to design practical study in order to contribute to the urban environment in Korea.

• Journal of the Korean association of regional geographers
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• v.7 no.2
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• pp.35-54
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• 2001

The construction of Daedeok Science Town, located in Yuseong ward of Daejeon metropolitan city, began in the early 1970s. It started out as a national project to form an agglomeration of the major central government research institutions. Since that time Daedeok Science Town has also attracted private research institutions, mainly during the 1900s. This study geographically analyzes this research institutions to clarify the regional identity of Daedeok Science Town through an integrated approach of existing new regional geography approach, which is characteristics of labour market as the regional pattern of its laborers' residences, spatial labour division, its research network with other institutions, and networks of university, research institution, and corporations, through the spatial spread of intellectual right of property and through network of technology business incubator relationship with spin offs which is appeared to spatial interaction. The results of the study are as follows: First of all, Daedeok Science Town was not only self-sustenance with marketing garden of agricultural regions in the suburb of Daejeon city but also was consign of agricultural products to Daejeon city before 1972. Since that time, the identity of Daedeok Science town has been formed by externally factors of the science development, by the local decentralization of population and public offices in Seoul metropolitan area in terms of the world economy system, and by the internally accessibility maximization of the central location in Korea between 1992 and 1999. On the part of Daedeok Science Town it has some merits of in-migration from nation-wide, and of mother city's Daejeon. Lastly at the period of the venture business beginning after 1999, the role of institution, developing the existing high technology, made great contribution to an attraction of ventures business to here in need of high technology industry growth, including knowledge-based industry in the informated society. On these bases, Daedeok Science Town seems to grow spontaneously as a science park.

• Journal of the Korean association of regional geographers
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• v.21 no.1
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• pp.176-191
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• 2015

Military Geography is a literature studying the application of geographical elements to military behaviour. The elements of military geography including topography greatly influences on building military art and theory. The military art applied on korean pennisula from the period of ancient three countries(Koguryeo, Shilla, Paekche) has been developed maintaining consistent stream reflecting topographic features. Despite the close relationship between building of military art and military geography's elements, the study for korean military geography has been depressed and the discourses of literature has been insufficient. But, in the western study of military geography, the study vitalization efforts studying military peace keeping and humanitarism activity are ongoing. Based on the current trend of western study and the analysis of existing korean study, this treatise proposes three plans to improve the study and education of korean military geography. The key contents of plans are comprised with the improvement of education curriculum, the construction of council between relevant organism, and the installation of subdivision in relevant geographical society. The possibility shaping up the identity of korean military geography as a common literature can be increased by enhancing the study toward peace and humanitarism and specifying the method for development as noted on this study.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.499-510
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• 2015

Artificial accelerated weathering test evaluated rocks from near the circuit road of Ulleungdo island, approximately 120 km from east of the Korean Peninsula. The tests subjected rock specimens to conditions based on the climate of the island. The specimens (such as basaltic breccia, trachyte, volcanic breccia) were preliminarily classified using a TAS diagram (XRF data) and based on the constituent minerals (XRD data); they were further classified by weathering degree according to their absorption ratios. During the artificial accelerated weathering, the absorption ratio of most of the specimens increased, but the point-load strength did not decrease in most cases, except for the volcanic breccia. The greater initial absorption ratio of trachyte rock specimen in comparison with the other specimens led to a greater increase of its absorption ratio during the artificial accelerated weathering test. The volcanic breccia specimens showed the greatest increase of absorption ratio and the biggest reduction ratio of the point- load strength during the tests. These results could aid prediction of the weathering rate of rocks in Ulleungdo island subjected to weathering processes; trachyte which appears to accelerate with time, and volcanic breccia whose mechanical strength can largely decrease in a relative short period of time. Proper measures therefore appear necessary for the prevention of natural disaster such as rock fall and landslide around the circuit road.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.53-61
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• 2008

Public Key Broadcast Encryption (PKBE) allows a sender to distribute a message to a changing set of users over an insecure channel. PKBE schemes should be able to dynamically exclude (i.e., revoke) a certain subset of users from decrypting a ciphertext, so that only remaining users can decrypt the ciphertext. Another important requirement is for the scheme to be forward-secrecy. A forward-secure PKBE (fs-PKBE) enables each user to update his private key periodically. This updated private key prevents an adversary from obtain the private key for certain past period, which property is particularly needed for pay-TV systems. In this paper, we present a fs-PKBE scheme where both ciphertexts and private keys are of $O(\sqrt{n})$ size. Our PKBE construction is based on Boneh-Boyen-Goh's hierarchical identity-based encryption scheme. To provide the forward-secrecy with our PKBE scheme, we again use the delegation mechanism for lower level identities, introduced in the BBG scheme. We prove chosen ciphertext security of the proposed scheme under the Bilinear Diffie-Hellman Exponent assumption without random oracles.

• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.367-378
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• 2018

Purpose: The objective of this study is to present a reasonable safety management of the anchored in-situ wall systems constructed in the ground conditions consisting of multi-layered soils underlain by bedrocks in the urban area of Korea. Method: Field measurements collected from collapse case histories with deep excavations were analyzed for the safety management of the wall systems supported by the earth anchors in terms of lateral displacement rates. Results: The average maximum lateral displacement rate in a collapsed zone of the in-situ wall significantly increased upon the completion of the excavation. Particularly, the collapse of the in-situ wall system due to the sliding occurring along the discontinuities of the rock produced a considerably large lateral displacement rate over a relatively short period. Conclusion: For predicting and preventing the collapse of the wall system during or after the excavation work, the utilization of the safety management criteria of the in-situ wall system by the lateral displacement rate was found to be much more reasonable in judging the safety of earthworks than the application of the quantitative management criteria which have been commonly used in the excavation sites.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1968-1975
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• 2011

This study was performed to propose a development guide for the periphery of local industrial park in the region of Hongseng-gun located at the mid-west of Chungnam province., which is a representative agrarian society, has been approached to a super-aged society where the region shows a continuous decrease in population, and the composition ratio of old ages is about 17.1%. Also, the region is a period of a low ebb due to the traditional agriculture based industrial structure in producing mainly simple productions. Many local governments in agrarian and fishing regions have been efforted for luring some businesses in their regions by constructing industrial complex competitively in order to solve such structural problems in such local regions. However, in some cases, these efforts cause certain destructions in the local original natural environment due to such development of industrial complex and the decrease in the settlement environment of residents. The objective of this study is to establish a local development plan for building the sustainable and comfortable settlement environments based on the settlement of the residents and the labors in such industrial complex by preventing sprawl developments in the construction of general industrial complex. This study was processed as following procedures. First, this study drew the trend in the change of the local society of H-gun through collecting literatures and analyzing it. Second, this study proposed a proper level of settlement environments required to the development of surroundings in such industrial complex based on the survey of the consciousness of residents using a statistical method. Finally, this study proposed a development guide for the surroundings based on the proposed level of settlement environments.