• Tunnel and Underground Space
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• v.19 no.6
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• pp.473-478
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• 2009

The accuracy of point load apparatus is depend on point to point coaxial fitting. Also, the estimation of applied point load using the pressure gauge frequently lead to erroneous results. An improved point load apparatus has been developed in this study by mounting linear bearing on polished support rod, and eccentric error of point to point axis has been sustained less than 0.1 mm even under series of extreme work load conditions. Two digital displacement gauges are attached to measure the distance from point to point with sample specimen. A load cell mounted at the end of upper conical platen measure the applied net load on sample instead of preassure gauge. Total of 107 point load tests has been achieved to assure the quality and performance of developed apparatus. This exercise turned out to be successful.

• Spatial Information Research
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• v.20 no.2
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• pp.45-57
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• 2012

Recently, local governments in Korea are promoting the rapid development of marine for delineating jurisdictional sea area. The importance of a maritime boundary has being emphasized, as jurisdictional sea area disputes among local governments have been increasing. The absence of the delineating standard of maritime boundary has become a source of contention between neighborhood local governments. So the delineating standard of maritime boundary in Korea will be required. The purpose of this study is to derive an improvement plan for the scientific delimitation standard of maritime boundary by analyzing "A hydrographic survey guideline for confirmation of maritime boundary". The results of this study are as follows. Firstly, we defined the concept of the delimitation standard of maritime boundary. Secondly, we set the boundary, factors and processes of the delineating standard of maritime boundary through classifying them in detail. Lastly, we suggested the makeup of a conflict adjustment committee for preventing jurisdictional sea area disputes among local governments.

• Tunnel and Underground Space
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• v.25 no.5
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• pp.435-449
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• 2015

Physical and microstructural properties of Pungchon and Maggol limestone were investigated quantitatively during 50 cycles of artificial freezing and thawing test. There were decrease in dry weight and P,S-wave velocity, and increase in absorption rate in both rock types. Porosity, pore volume, equivalent diameter, throat thickness and pore orientation were analyzed using X-ray computed tomography images. Porosity increased, and initiation and expansion of pores were investigated as weathering progresses. Physical and microstructural variation in Maggol limestone was larger than that of Pungchon limestone because Maggol limestone has more pores and microcracks at initial state. As this study analyzes physical and microstructural properties of rock specimens comprehensively, it can be applied to further rock weathering study and can be used as fundamental data of construction and resource development in cold regions.

• Journal of Science and Technology Studies
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• v.9 no.1
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• pp.57-87
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• 2009

Sick House Syndrome(SHS) is the environmental health problem which is difficult to clarify a causal relationship and a responsibility. This paper is focused on a National Environmental Dispute Resolution Commission(NEDRC)'s judgment on SHS and the process of the change of knowledge and policies related to SHS. In the process of the resolving the SHS dispute, NEDRC functioned as a boundary organization, which helps stabilize the boundary between science and policy, and provides space of mutual collaboration and produces boundary objects. NEDRC had necessary characteristics and resources to make scientific knowledge and policies of SHS. First, it was important for SHS to define a problem clearly and to justify the related information whereupon legal authority was effective. In addition, for the procedure of deciding polities, the role of the Ministry of Environment(ME) was essential. However, due to the condition of ME, the discussion of SHS had been limited to the scope of dispute, excluding scientific discussion.

• Journal of the Korean Geographical Society
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• v.43 no.2
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• pp.220-234
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• 2008

In many security monitoring contexts, the performance or efficiency of surveillance sensors/networks based on a single sensor type may be limited by environmental conditions, like illumination change. It is well known that different modes of sensors can be complementary, compensating for failures or limitations of individual sensor types. From a location analysis and modeling perspective, a challenge is how to locate different modes of sensors to support security monitoring. A coverage-based optimization model is proposed as a way to simultaneously site k different sensor types. This model considers common coverage among different sensor types as well as overlapping coverage for individual sensor types. The developed model is used to site sensors in an urban area. Computational results show that common and overlapping coverage can be modeled simultaneously, and a rich set of solutions exists reflecting the tradeoff between common and overlapping coverage.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.120-130
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• 2016

Considering the applicability of Kuz-Ram model, which has been used extensively for predicting rock fragmentation size distribution by blasting, to domestic open-pit limestone mine, a total of 21 blasting tests have been executed at an open-pit limestone mine in eastern Gangwon of South Korea. A comparative analysis of field measured value and Kuz-Ram predicted value showed that there are a considerable amount of error in the predicted values regardless of application of various correction parameters for rock factor and uniformity factor; up to 56.45% in mean fragmentation size and 37.52% in uniformity index. Also the problem of applying different correction parameters has been derived even though a similar blasting pattern has been adopted for a same blasting bench. The authors therefore suggest that Kuz-Ram model needs to be modified for a proper application to domestic open-pit limestone mine.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2113-2120
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• 2013

As a smart mobile device is gaining popularity as a tool to utilize internet services, the demand on the cloud service (which eliminates the spatial and/or temporal restrictions in enjoying the services) is increasing. This trend also has an effect on the style of performing business tasks so that the concept of 'smart-work' (e.g. doing business tasks in anywhere and anytime) is being spread over the industries. The facilities for the smart-work is, however, focused on providing the tools designed to supporting business tasks such as co-working in writing documents, video conference, searching data via smart (mobile) devices neglecting the industries' needs for the infrastructure by which they can create their own business applications and mobile cloud services at a low (or moderate) price. The paper proposes a mobile cloud service platform, which provides an SDK for developing business applications and offers the applications to smart mobile devices as a PaaS (Platform as a Service).

• Tunnel and Underground Space
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• v.16 no.4 s.63
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• pp.334-346
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• 2006

The discrete element code in 2-D, PFC2D, has been used as a tool to simulate various phenomena in rock mechanics and rock engineering. However, the code has an disadvantage that procedure to determine micro-parameters, namely properties of particles and contacts is repetitive and time-consuming. In this study, we analyzed the effect of micro-parameters(for generation of a contact-bonded model) on macro-properties(that were measured numerically by uniaxial compressive test). Based on the analysis, also, the time-saving and reliable method was suggested to determine a complete set of micro-parameters. In order to verify the suggested method, numerical specimens were generated in PFC2D for 10 different rock types at home and abroad. By the two trials for each specimen, in the result, the Young's modulus, Poisson's ratio and uniaxial compressive strength could be reproduced with being in relative error by about 5% to the values obtained by laboratory tests.

• Explosives and Blasting
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• v.30 no.1
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• pp.29-36
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• 2012

In this study, the influence of priming location inside a blast hole on the ground vibration has been studied. In most of the previous studies dealing with the ground vibration, the effect of priming location in a blast hole was usually considered in a limited way. Thus, it seems that the results of the studies can be applicable only to the relevant sites. Considering the fact that the mechanism of ground vibration caused by blasting is quite complex, the priming location can have a considerable effect on the ground vibration in certain situations and be an important parameter in a blasting design. To identify the characteristics of the wave propagation according to priming locations, total 72 test blasts were carried out with different spacing, burden, drilling length, and charge, and prediction equations were derived. The characteristics of ground vibration, which was changed according to the priming location, was analyzed by using the nomogram of peak particle velocity (PPV) record. Attenuation relations, which were also dependent on the priming location, were analyzed. In this case, four different amounts of charge, that is, 0.5, 1.6, 5, and 15 kg, were used for the test. This criterion of charge amount is specified in the "Blasting design and construction guidelines to road construction" by the Ministry of Land, Transport and Maritime Affairs of Korea.

• School Mathematics
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• v.5 no.1
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• pp.77-95
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• 2003

We have web-based online discussion to implement active interaction and a variety of communicative activities. I have gathered the following research questions to study about the meaning of web-based online discussion as a mathematical communication teaching method. First, what changes are there in students mathematical communication ability in web-based online discussion\ulcorner Second, how do students evaluate the web-based online discussion experience\ulcorner In this web-based online discussion, groups of middle school first grade 34 students and each group had chatting at 8 times for 10 weeks. I analyzed what they had discussed by the prints that they had sent me by e-mail. I also surveyed what they had experienced and analyzed them. In this research, the online web based discussion has given positive influence on students' competence of speaking, writing, reading and listening which are crucial to mathematical communication. Students' mathematic thinking power improved and attitudes to mathematics have become more positive.