• Tunnel and Underground Space
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• v.14 no.6 s.53
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• pp.440-449
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• 2004

Rock mass includes natural discontinuities such as joints and faults during its formation. Discontinuities are also referred as planes of weakness because of their weak mechanical characteristics. In the design of underground structures, it is necessary to consider the properties of discontinuities to insure the stability. During the excavation of a tunnel, these discontinuities have to be identified as early as possible so that proper change in excavation method or support design can be made accordingly. The excavation of the tunnel in a stable rock mass causes a 3-dimensional arching effect around the excavation face. It was revealed by previous studies that the existence of a weak zone or a fault zone ahead of tunnel foe induces a typical displacement tendency of convergence. For better understanding of the meaning of influence/trend lines of various displacement components, three-dimensional numerical analyses were conducted while varying deformation moduli, thicknesses and orientations of discontinuities. Numerical results showed that the changes in influence/trend lines of various displacement components were very similar to those by measurements. The discrepancies from the expected values were dependent on the physical properties, thicknesses and orientations of discontinuities.

• Tunnel and Underground Space
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• v.21 no.4
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• pp.320-327
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• 2011

In this study, for stemming effect in blast of the mortar block body, the crushed granite sand as fine aggregate, which is waste rock obtained at the ○○ limestone mine, was investigated to compare with stemming materials such as sea sand, river sand, clayed soil and water can be acquired easily at the field. The mortar block body was manufactured with the dimensions of 50 cm width, 50 cm length and 70 cm height. The direct shear and sieve separator test were performed, and the properties of friction resistance were analyzed by the extrusion test for five stemming materials. Axial strain of steel bar and ejection velocity of stemming materials due to the explosive shock pressure in blasthole with the stemming length of 10 cm and 20 cm in the mortar blast test were measured by the dynamic data acquisition system. Among stemming materials, axial strain showed the largest value at the crushed granite sand as fine aggregate, and the ejection velocity was the smallest value at the stemming of water. The results has shown correlate with harden unit weight in blasthole, particle size distribution, shear resistance, and extrusion strength of stemming materials. The ejection velocity of stemming material at the mouth of blasthole and the axial strain of steel bar in the inside of blasthole tend to be inversely proportional to each other, represent exponentially.

• Tunnel and Underground Space
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• v.26 no.5
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• pp.396-408
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• 2016

Rock fracture mechanics has been widely applied to various fields of rock and civil engineering. But most researches covered mode I behavior, though mode II behavior is dominant in rock engineering. Until now, there is only one ISRM suggested method for mode II toughness of rock. A new SCC (Short Core in Compression) mode II toughness test method was developed considering 1) application of confining pressure, 2) easiness of notch creation, 3) utilization of existing equipment, 4) simple test procedure. The stress intensity factors were determined by 3D finite element method considering line and distributed loading conditions. The tests with granite specimens were carried out using MTS 815 rock test system with a loading rate of 0.002 mm/s. The mean value of mode II fracture toughness of granite showed $2.33MPa{\sqrt{m}}$. Mode I toughness of the same granite was $1.12MPa{\sqrt{m}}$, determined by Brazilian disk test and $K_{IIC}/K_{IC}=2.08$. The smooth fracture surface with rock powder formation also supported mode II behavior of SCC method. The SCC method can be used for the determination of mode II fracture toughness of rocks based on the current results.

• Korean Journal of Remote Sensing
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• v.36 no.2_1
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• pp.139-153
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• 2020

Using a computationalfluid dynamics(CFD) model, thisstudy evaluated the representativeness of an air quality monitoring system (AQMS) in an urban area and presented a methodology to determine the suitable AQMS locations for specific purposes. For this, we selected a 1.6 km × 1.6 km area around the Eunpyeong-gu AQMS (AQMS 111181) as a target area. We conducted simulationsfor two emission scenarios (scenario one: air pollutants transported from inflow boundaries, scenario two: air pollutants emitted from roads). Urban airflows were markedly influenced by mountainous terrain located in the northeast and southeast of the target area, and complicated airflow patterns occurred around the buildings. The distributions of air pollutants were dependent on the terrain (mountain) in scenario one, but the road location and building height in scenario 2. We evaluated whether the AQMS could represent the air quality in the target area based on the simulations for two scenarios. The concentrations simulated at the AQMS were similar in magnitude to the layer mean concentrations, which indicated good representativeness for the air quality in the target area. We also suggested which locations were suitable for different measurement purposes (hot spots, clean zones, average zones, shelter zones, equi-background zones).

• Economic and Environmental Geology
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• v.53 no.2
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• pp.147-157
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• 2020

Mass change in the Antarctic Ice Sheet(AIS) is the most important indicator of changes in Earth's climate system including global mean sea level rise that are largely affected by ongoing global warming. In this study, AIS mass variations are examined with satellite gravity data and outputs from a regional climate model. The analysis of gravity data shows that along the coastal region the Western AIS has experienced a continuous and significant ice loss while a slight increasing in the Eastern AIS during the study period (2002.08-2016.08). The temporal and spatial variations in ice mass changes are recovered by a regional climate model, but the recovered amplitudes are much smaller than those of observations. This under-estimation is remarkably resolved by modifying a base flow field for the ice discharge. The recovered estimates based on the ice-flow field can explain about 97% of the rate of mass change in observations before 2009. This implies that changes in ice flow dynamics along the coast line plays a pivotal role in regulating long-term budget of ice mass in AIS.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1070-1078
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• 1998

Thermodynamic analysis on carbon dioxide reforming of methane was performed using a computer program which can handle condensed species in the products, and the reforming experiments were conducted over $Al_2O_3$, $La_2O_3$, ZSM-5, MCM-41, KIT-1 supported nickel catalysts, and a commercial ICI 46-1. It was estabished that a system which consists of $CH_4$, $CO_2$, CO, $H_2$, $H_2O$, and C is appropriate for theoretical equilibrium calculations and addition of water vapor or oxygen was found to diminish the contribution of carbon dioxide in reforming. Silicate molecular sieve-supported catalysts such as Ni/ZSM-5, Ni/MCM-41, Ni/KIT-1 were effective for high $CH_4$ and $CO_2$ conversions as well as for high CO yield. Coke formation was suppressed when CaO was added as a promoter. Ni/Ca/KIT-1 which contains 10% Ni with 3% Ca showed conversion approaching equilibrium levels above $650^{\circ}C$ and maintained constant activity over 20 h. Despite increased space velocity, relatively high conversion and CO yield were observed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.263-271
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• 2018

The purpose of this study is to find that people's visit to a dementia home exhibition hall is effective at improving their perception of dementia. The satisfaction of visitors to the dementia home exhibition hall and a change in their perception of dementia after the visit were analyzed. The study subjects were 52 residents in S city. This study had been conducted from April, 5 to May, 25, 2018. The dementia home exhibition hall has welfare kits installed in an entrance, a rest room, a living, and a kitchen. Virtual reality experience program and the program of wearing clothes to experience an elderly person were performed together. As a result, the visitors' satisfaction was high overall, and their visit was educationally effective at improving their perception of dementia. After their visit to the hall, the residents showed high increases in the scores of the questions about the perception of dementia causes, dynamism & system, symptoms & diagnosis, and treatment & prevention. The residents with middle years and higher of age were more satisfied than those in other age groups with the introduction of dementia, and prevention methods, introduction of safe and comfortable home environment, and appropriateness of experience program. In this study, it was positive that the differentiated experience program which was not existed actively led the participation of the target person and attracted high education satisfaction in a short time. In the future, it will be necessary to develop an extended experience program, provide an environment for direct experience of dementia, and perform a continuous program to draw more citizens' attention.

• Journal of Korean Medical classics
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• v.13 no.2 s.17
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• pp.58-67
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• 2000

통과대문왕팔괘차서도화문왕팔괘방위도적연구(通過對文王八卦次序圖和文王八卦方位圖的硏究). 득도요여하결론(得到了如下結論). 1. 최초명명위문왕팔괘차서도화문왕팔괘방위도적인시소옹(最初命名爲文王八卦次序圖和文王八卦方位圖的人是邵雍). 문왕팔괘차서도화문왕팔괘방위도수연몰유시문왕소화적확체적근거(文王八卦次序圖和文王八卦方位圖雖然沒有是文王所畵的確切的根據), 단시종추연복희이(但是從推演伏羲易), 동사상결합(同事相結合), 최종확립여금적역학체계적인시문왕(最終確立如今的易學體系的人是文王). 이차환부합현금적역리(而且還符合現今的易理), 인차구유일정설복력(因此具有一定說服力). 2. 재문왕팔괘차서도중삼남유일양이음구성(在文王八卦次序圖中三男由一陽二陰構成). 삼녀유일음이양구성(三女由一陰二陽構成). 저가이용음양호근적원리진행설명(這可以用陰陽互根的原理進行說明). 3. 복희팔괘방위도현시모종공간상(伏羲八卦方位圖顯示某種空間相). 이문왕팔괘방위도칙현시사시(而文王八卦方位圖則顯示四時). 팔절적변화화만물생장적류행주기등시간상적변화(八節的變化和萬物生長的流行周期等時間上的變化). 4. 문왕팔괘방위도동사시적오행상일치(文王八卦方位圖同四時的五行相一致). 시상생관계(是相生關係), 팔괘당중각유양개목김토(八卦當中各有兩개木金土). 시유우형흔왕성(是由于形흔旺盛), 수화각유일개시유우기흔왕성(水火各有一개是由于氣흔旺盛). 5. 문왕팔괘방위도재표면상간호상시오행상생적관계(文王八卦方位圖在表面上看好象是五行相生的關係). 단시(但是), 상호성대면적팔괘적오행도성상극관계(相互成對面的八卦的五行都成相剋關係). 화동측상임적감수(和東側相臨的坎水) 간토(艮土) 진목(震木) 손목도시성상극관계(孫木都是成相剋關係). 종차가이지도상극시발전만물적주체(從此可以知道相剋是發展萬物的主體). 6. 대우복희팔괘전화위문왕팔괘적원리(對于伏羲八卦轉化爲文王八卦的原理), 수유각종이론제출(雖有各種理論提出). 단시상무확체적설법(但是尙無確切的說法). 7. 복희팔괘주요체현천도화외상등(伏羲八卦主要體現天道和外象等), 문왕팔괘측체현인사화내정등(文王八卦側體現人事和內情等). 8. 복희팔괘위체(伏羲八卦爲體), 문왕팔괘위용(文王八卦爲用). 복희팔괘중(伏羲八卦中), 위변화적주체적천지즉건곤위우중축(爲變化的主體的天地卽乾坤位于中軸). 문왕팔괘중(文王八卦中), 위변화적대용적일월즉감리위우중축(位變化的大用的日月卽坎離位于中軸). 9. 복희팔괘도속우표현춘천적변화지상적제일괘도(伏羲八卦圖屬于表現春天的變化之象的第一掛圖), 생괘도화창조도(生掛圖和倉曹圖), 문왕팔괘도칙속우표현하천적변화지상적제이괘도(文王八卦圖則屬于表現夏天的變化之象的第二掛圖), 장괘도화발전도(長掛圖和發展圖). 10. 문왕팔괘도시류행이치기용적역지용(文王八卦圖是流行以致其用的易之用), 표현무질서화혼란(表現無秩序和混亂), 위화여괴리상호란무적난음난양지상(韋和與乖離相互亂舞的亂陰亂陽之象). 11. 문왕팔괘도화낙서적변화원리상일치(文王八卦圖和洛書的變化原理相一致), 가이장낙서적수직접대응도문왕팔괘도중(可以將洛書的數直接對應到文王八卦圖中). 우명낙서팔괘도(又名洛書八卦圖). 구수도혹일구역(九數圖或一九易). 12. 문왕팔괘도적상대응적수자지합도위십(文王八卦圖的相對應的數字之合都爲十). 저예시료성괘도십수도적출현(這豫示了成掛圖十數圖的出現).

• Tunnel and Underground Space
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• v.25 no.1
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• pp.97-106
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• 2015

We must precisely investigate the mechanical characters of rock to design rock slope safely and efficiently. But the method of clinometer has some disadvantages. So, we need a new measurement that can replace the method of clinometer. In this study, we analyze the reliability of joint orientation measurements in rock slope using the 3D laser scanner and program Split-FX that is a point cloud data analysis software. We could acquire the 495 pieces joint data through the automatic extraction of features. And we confirmed that there were some errors occurred with ${\pm}4^{\circ}$ of dip and ${\pm}5^{\circ}$ of dip direction. Generally, the method of clinometer has ${\pm}5^{\circ}$ and ${\pm}10^{\circ}$ error ranges of the joint orientation(dip/dip direction) that are the results of the advance research. Therefore, we analyzed the method of 3D laser scanner, and it is found to be efficient, reliable. This method is expected to mend the disadvantages of Clinometer method.

• Tunnel and Underground Space
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• v.23 no.4
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• pp.308-318
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• 2013

Thermal stratification in heat stores is essential to improve the efficiency of energy storage systems and deliver more useful energy on demand. It is generally well known that the degree of thermal stratification in heat stores varies depending on the aspect ratio (the height-to-width ratio) and size of the stores. The present study aims to investigate the effect of the aspect ratio and storage volume of rock caverns for storing hot water on thermal stratification in the caverns and heat loss to the surroundings. Heat transfer simulations using a computational fluid dynamics code, FLUENT were performed at different aspect ratios and storage volumes of rock caverns. The variation of thermal stratification with respect to time was examined using an index to quantify the degree of stratification, and the heat loss to the surroundings was evaluated. The results of the numerical simulations demonstrated that the thermal stratification in rock caverns was improved by increasing the aspect ratio, but this effect was not remarkable beyond an aspect ratio of 3-4. When the storage volume of rock caverns was large, a higher thermal stratification was maintained for a relatively longer time compared to caverns with a small storage volume, but the difference in thermal stratification between the two cases tended to decrease as the aspect ratio became larger. In addition, the numerical results showed that the heat loss to the surrounding rock tended to increase with an increase in aspect ratio because the surface area of rock caverns increased as the aspect ratio became larger. The total heat loss from multiple small caverns with a reduced storage volume per cavern was larger compared to a single cavern with the same total storage volume as that of the multiple caverns.