• Tunnel and Underground Space
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• v.8 no.4
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• pp.332-341
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• 1998

Conventional polishing of stone panel edges has been done by hand. While this has changed somewhat with the advent of automatic machines, it is still very much a hand finishing technology. For the development of edge shape milling tool, the primary test on characteristics of edge shape milling tool was carried out. This paper presents the results of tests focused upon the milling capability that was varied by the variables of operation parameters. Author tried to confirm the effect of six operation parameters of equipment such as rotation speed, advance speed, applied load, water flow rate and rotational direction. The result from test was described in term of shape milling capability that was defined as cutting volume of rock by unit weight of tool wear. The variance of the results could indicate the optimum level of each operating parameters. The test was also carried out to determine the abrasion resistance varied according to the abrasive flow rate. The abrasion resistance was increased with the abrasive flow rate, but over some rate it was not changed.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.144-156
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• 2012

This paper discusses the methods of estimating the punch penetration indices and data analysis punch penetration test to estimate the TBM normal force and penetration rate. In punch penetration test is known as a useful test to estimate penetration rates and normal force of TBMs directly with several slope indices indicated drill-ability and brittleness of rocks. However, the standard methods and indices for punch penetration test are not suggested yet. The main purpose of punch penetration test which is prediction of normal force of TBM disc cutter when cutters excavate rock mass. In this study, the punch penetration tests were performed for 6 representative Korean rock types and variety length and diameter of rock core specimens. Among slope indices were obtained from punch penetration test, PLI and MLI which is suggested in this study show high correlation with cutter force measured by full-scale cutting test. The results show that the predicted normal force of a single disc cutter and the experimental error was 10%. Based on these results, it is concluded that punch penetration test is reliable laboratory test for estimating thrust and penetration rates of TBM.

• Journal of The Korean Association For Science Education
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• v.35 no.4
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• pp.677-689
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• 2015

The purpose of this study is to derive suggestions and implications to strengthen the science curriculum continuity of Korea through comparative analysis with focus on the continuity of science curriculum in six countries (Taiwan, the United Kingdom, Finland, the United States, Canada, Korea). Original and Korean translations of the national curriculums of each country gathered from NCIC comparatively analyzed the contents of the 'Moon' and 'Rock cycle' based on features of curriculum configuration, vertical, and lateral connectivity. As a result, it was found that the concepts of Big Ideas or Cross-cutting Concept was utilized internationally to strengthen the linkage between grades or subjects. In particular, dealing with the aspect of the system was important. In the comparison of countries for the content, Korea deals with the most frequency on the 'Moon' and 'Rock cycle'. The contents of the chapter about the moon were simply repeated from elementary to high school levels with some variation. Korean science curriculum holds different perspectives and contents about the Rock cycle compared to other countries. In conclusion, Korea's curriculum requires appropriate tools to strengthen curriculum linkage and by doing so, it will be able to take advantage of the systems approach. Moreover, it is important to constitute the curriculum based on a sufficient understanding of the learning development of students according to their grade levels for the effective application of the curriculum.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.37-44
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• 2018

This study proposed the modified weighting values for jointed rock slopes. The studies on deduction of evaluation index and calculation of weighting, development of criteria for evaluation and evaluation models have been conducted through decision making techniques such as the Delphi method and the AHP method by many researchers. Because these decisions making techniques may be less objective, it is necessary to calculate reasonable weighting considering both an objective weighting and a subjective weighting simultaneously. In this study, utilizing the inspection data of jointed rock slopes, an objective weighting that the concept of entropy is applied was calculated. And the subjective weighting values by AHP technique was calculated based on the opinion of experts. And a modified weighting was suggested by combining the two. As a result, it was found that jointed rock slopes have higher weighting in artificial factors and the damage status items. In addition based on the finally suggested weighting (mixed weighting), the revised evaluation criteria could be presented by converting it into the evaluation score (76 points). And it is expected that it could be usefully utilized upon inspections on cutting slopes and safety diagnosis since objective and highly reliable criteria compared to the condition evaluation criteria that are currently used could be presented through the results of the study.

• Journal of Powder Materials
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• v.5 no.4
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• pp.303-311
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• 1998

Hard materials such as hardmetal, coated hardmetal, cermet, ceramics and diamond or c-BN sintered compact are a kind of grain-dispersed alloy with high volume of hard particles. These are used for cutting tools, wear-resistant tools, rock bits, high pressure apparatus, etc. The annual production in Japan is about 1.7 billion dollars (200 billion yen). This is greatly owed to the development in science and technology which has been accomplished by applying new concepts such as fine or uniform grain microstructure, orientation of crystal grains, functionally graded material, artificial lattice and coherent bonding in recent years. In this review, the development in recent years in Japan is briefly summarized.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.51-60
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• 2006

At new constructing national road, a cutting slope was surveyed and gotten face mapping for three months. The slope is composed of gray phyllite and coaly slate which is the Chang-ri Formation, Okcheon system. The slope angle is 40 degree and the direction is NNE. The attitude of schistosity is $260^{\circ}/45^{\circ}$. So the slope direction is nearly parallel to the schistosity. This is the reason that the slope is very unstable. On the other hand, the very unstable slope is caused by the direction of the schistosity and the slope. First month the coaly slate was slided through the schistosity plane about 10cm. However, three months late the displacement was 2m maximum.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.162-163
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• 2016

This paper presents a mathematical model for optimizing earthwork allocation plan that minimizes earthwork cost. The model takes into account operational constraints in the real-world earthwork such as material-type (i.e., quality level of material) and quantities excavated from cut-sections, required quality of material and quantities for each embankment layer, top-down cutting and bottom-up filling constraints, and allocation orders. These constraints are successfully handled by assuming the rock-earth material as the three dimensional (3D) blocks. The study is of value to project scheduler because the model identifies the optimal earth allocation plan (i.e., haul direction (cut and fill pairs), quantities of soil, type of material, and order of allocations) expeditiously and is developed as an automated system for usability. It is also relevant to estimator in that it computes more realistic earthworks costs estimation. The economic impact and validity of the mathematical model was confirmed by performing test cases.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.305-313
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• 2020

The use of cable tunnels for electric power transmission as well as their construction in difficult conditions such as in subsea terrains and large overburden areas has increased. So, in order to efficiently operate the small diameter shield TBM (Tunnel Boring Machine), the estimation of advance rate and development of a design model is necessary. However, due to limited scope of survey and face mapping, it is very difficult to match the rock mass characteristics and TBM operational data in order to achieve their mutual relationships and to develop an advance rate model. Also, the working mechanism of previously utilized linear cutting machine is slightly different than the real excavation mechanism owing to the penetration of a number of disc cutters taking place at the same time in the rock mass in conjunction with rotation of the cutterhead. So, in order to suggest the advance rate and machine design models for small diameter TBMs, an EPB (Earth Pressure Balance) shield TBM having 3.54 m diameter cutterhead was manufactured and 19 cases of full-scale tunneling tests were performed each in 87.5 ㎥ volume of artificial rock mass. The relationships between advance rate and machine data were effectively analyzed by performing the tests in homogeneous rock mass with 70 MPa uniaxial compressive strength according to the TBM operational parameters such as thrust force and RPM of cutterhead. The utilization of the recorded penetration depth and torque values in the development of models is more accurate and realistic since they were derived through real excavation mechanism. The relationships between normal force on single disc cutter and penetration depth as well as between normal force and rolling force were suggested in this study. The prediction of advance rate and design of TBM can be performed in rock mass having 70 MPa strength using these relationships. An effort was made to improve the application of the developed model by applying the FPI (Field Penetration Index) concept which can overcome the limitation of 100% RQD (Rock Quality Designation) in artificial rock mass.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.2
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• pp.227-234
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• 2006

Ministry of construction & transportation is operating for the soil and rock information system and is considered to accurate application of soil conversion factor that is essentially necessary for accurate calculation of earth volume. Since the balance of cutting earth in public work, the plan of spoil bank or borrow pit are directly related to construction costs, accurate calculation of earth volume and efficient scheme of haul are important. As such, this study has provided methods that can acquire information that is more rapid, applicable to job sites, and trustworthy by comparing resultant values of photogrammetry, laser scanning, or inside job site experimentations, and calculated soil conversion factor by applying photogrammetry and laser scanning methods for hard rock that has difficulty in calculating soil conversion factor. The study can provide alternatives that can resolve the problems of unbalanced earth volume that may arise in applying to plans the earth conversion factor that relies on planning books and experience without considering the characteristics of job site earth, and can establish its relevancy by calculating soil conversion factor for hard rock that has relative difficulties in doing inside or job site testing.

• Tunnel and Underground Space
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• v.24 no.6
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• pp.405-417
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• 2014

In a high-level waste repository, the gap fill of the engineered barrier is an important component that influences the performance of the buffer and backfill. This paper reviewed the overseas status of R&D on the gap fill used engineered barriers, through which the concept of the gap fill, manufacturing techniques, pellet-molding characteristics, and emplacement techniques were summarized. The concept of a gap fill differs for each country depending on its disposal type and concept. Bentonite has been considered a major material of a gap fill, and clay as an inert filler. Gap fill was used in the form of pellets, granules, or a pellet-granule blend. Pellets are manufactured through one of the following techniques: static compaction, roller compression, or extrusion-cutting. Among these techniques, countries have focused on developing advanced technologies of roller compression and extrusion-cutting techniques for industrial pellet production. The dry density and integrity of the pellet are sensitive to water content, constituent material, manufacturing technique, and pellet size, and are less sensitive to the pressure applied during the manufacturing. For the emplacement of the gap fill, pouring, pouring and tamping, and pouring with vibration techniques were used in the buffer gap of the vertical deposition hole; blowing through the use of shotcrete technology and auger placement and compaction techniques have been used in the gap of horizontal deposition hole and tunnel. However, these emplacement techniques are still technically at the beginning stage, and thus additional research and development are expected to be needed.