• Title/Summary/Keyword: Space Mineral

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Long-term strength of shotcrete with improved C12A7 based mineral accelerator (개량형 C12A7계 광물계 급결제를 사용한 숏크리트의 장기강도 평가)

  • Won, Jong-Pil;Hwang, Un-Jong;Lee, Su-Jin;Lee, Jae-Ho;Jang, Seok-Bu
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.2
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    • pp.135-148
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    • 2014
  • This study was performed to evaluate the performance about Improved C12A7 based mineral accelerator (ICM) increased in initial and long-term strength. ICM was developed to overcome the long-term strength decrease in existing accelerator. To evaluate the performance of ICM according to addition rate, setting time, compressive strength, and flexural strength tests were conducted in laboratory. In results, initial setting time was slower, final setting time was faster than existing $C_{12}A_7$ based mineral accelerator (CM) when usage of ICM 6%. In compressive and flexural strength, existing CM was higher than ICM at 3hours and 1day. After 7days, strength of shotcrete using ICM was increased. Rebound test, compressive strength and flexural strength test with optimum addition rate through the laboratory test were conducted in field. Field experiment results were the same as laboratory test. Long-term strength performance of ICM was superior to existing accelerator.

Bleeding characteristics of coupling materials for installation of acoustic emission (AE) sensor (AE 센서 설치를 위한 커플링 재료의 블리딩 특성)

  • Lee, Jong-Won;Kim, Hyunwoo;Kim, Min-Koan;Oh, Tae-Min
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.4
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    • pp.635-650
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    • 2017
  • Acoustic emission (AE) sensors have broadly used to monitor the damage of underground structures and tunnels. The reliability of measured signal is determined by the coupling condition of the AE sensors which are embedded in the target underground structure. To secure the reliability of health monitoring results, it is important to understand the characteristics of the coupling materials. In this study, laboratory tests were performed using portland cement, micro cement, and gypsum as coupling materials in order to verify the bleeding characteristics. The effective parameters for bleeding were determined to be water-cement ratio, material type, curing time, and injected volume of coupling materials. As a results of the experimental study, the bleeding rate increases with an increase in a water-cement ratio and an injected volume; for portland cement, water-cement ratio and injected volume effects are larger than the micro cement. However, curing time is not much effective for occurrence of the bleeding phenomenon. It is anticipated that this study may be useful for the selection of suitable coupling materials for installation of acoustic emission sensors.

A Review of the Space Mission to Mars up to Date (화성 우주 프로그램에 관한 현재까지 연구의 개요)

  • Kim, Kyeong-Ja
    • The Journal of the Petrological Society of Korea
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    • v.18 no.1
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    • pp.49-65
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    • 2009
  • Endlessly, mankind has been pursuing its dream toward understanding and conquering our neighboring planet, Mars since Mars has been identified as a planet. After the development of advanced science and technology of human race in 1960, the Union of Soviet Socialist Republics (USSR) had initiated its dream toward Mars and finally at present mankind acquires numerous important clues of Mars through over forties of space programs toward Mars. Furthermore, mankind takes its effort in colonizing Mars within several decades. This manuscript introduces the history of space mission programs of Mars up to date and major scientific findings to understand the Mars.

A Study on the Model Test for Pneumatic Mine-Filling (공압식 갱내충전을 위한 모형실험 연구)

  • Yang, In-Jae;Shin, Dong-Choon;Yoon, Byung-Sik;Mok, Jin-Ho;Kim, Hak-Sung;Lee, Sang-Eun
    • Tunnel and Underground Space
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    • v.24 no.6
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    • pp.449-463
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    • 2014
  • There are many case studies and application cases in abandoned mines for hydraulic filling method filled by slurry or paste form, but research on the pneumatic filling is not applied in Korea. The damage of steel pipe is occurred by wear due to the flow of filling material in the bent area of steel pipe in traditional pneumatic filling method. In this study, the new pneumatic filling method was developed using a newly devised improved nozzle to improve the above problem. The model test for mine filling was performed in the laboratory for the simulated accessible or inaccessible mine cavities, and the filling efficiency by the results obtained from the test was calculated. The filling efficiency was analyzed from the variation of outlet angle, feed rate and grain size of sand in model test of simulated accessible mine cavity. The superiority of improved pneumatic filling method was proved through the analysis of filling efficiency by the results obtained from each model tests of gravitational, traditional, and improved filling method in simulated inaccessible mine cavity.

Assessment of Rocks and Alteration Information Extraction using ASTER data for Övörkhangaii Province, Mongolia (ASTER 영상자료를 활용한 몽골 오보르항가이(Övörkhangai) 일대 암상 빛 변질 정보추출의 활용가능성 평가)

  • Jeong, Yongsik;Yu, Jaehyung;Koh, Sang-Mo;Heo, Chul-Ho
    • Economic and Environmental Geology
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    • v.48 no.4
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    • pp.325-335
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    • 2015
  • This study examined the possibility to extract potential alteration zones and lithologic information based on ASTER band ratio techniques for mineralized area located in ${\ddot{O}}v{\ddot{o}}rkhangai$ province, Mongolia, and the effectiveness of remote sensing as a preliminary exploration tool for mineral exploration was tested. The results of ABRLO, PBRLO, and PrBRLO models indicated that the detection of argillic zone requires the verification of the samples to verify hydrothermal alteration minerals as clay minerals can formed by weathering process, whereas phyllic-propylitic zones were considerably related to the spatial distribution of the intrusive bodies, geological structures, and ore distribution. QI and MI results showed that QI is more useful for sedimentary rocks such as conglomerate and sandstone than meta-sedimentary like quartzite, and MI faced relatively uncertain in detection of felsic or mafic silicate rocks. QI and MI may require additional geologic information such as the characteristics of samples and geological survey data to improve extraction of lithologic information, and, if so, it is expected that remote sensing technique would contribute significantly as a preliminary geological survey method.

Technology Readiness Levels (TRLs) Indicator Development for Geoscience and Mineral Resources R&D (지질자원 연구개발에 대한 기술개발단계(TRL) 지표 개발)

  • Ahn, Eun-Young;Kim, Seong-Yong;Lee, Jae-Wook
    • Economic and Environmental Geology
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    • v.48 no.5
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    • pp.421-429
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    • 2015
  • Base researches in geoscience and mineral resources, such as geological and geo-thematic mapping, geological survey and observation, have long-term, continuity and time-leasing characteristics and they are difficult to present the particular research stages or progressions in the research span. The Technology Readiness Levels (TRLs), developed by the U.S. National Aeronautics and Space Administration (NASA), is effective for presenting research maturity levels and progression in the development of new technologies. This study suggests adjusted definitions for the Technology Readiness Levels to fit Geo-technology (Technology in Geoscience and Mineral Resources). Base geological researches, including mapping, surveys and observation, can be also presented in research levels from TRL 1 (R&D planning, literature survey) to TRL 9 (geological information construction and service in all target areas) in terms of the final product's coverage. Moreover, not only development and construction of commercial products, geological disasters and environmental researches can also be presented in field demonstrations through public pilot applications. The modified commercialization or cemonstration TRLs in Geo-technology are TRL 5 (starting pilot field application), TRL 6 (pilot field operation) and TRL 7 (pilot field operation for a larger scale, greater than ten percent of the actual environment).

Geochemical Implication of Rare Earth Element pattern and Rb-Sr mineral isochron from consituent minerals in the Naedeokri-Nonggeori granite, Yeongnam Massif, Korea (영남육괴 북동부 내덕리-농거리 화강암내 구성광물의 희토류원소 분포도 및 Rb-Sr 광물연대의 지구화학적 의의)

  • Seung-Gu Lee;SeungRyeol Lee
    • Korean Journal of Mineralogy and Petrology
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    • v.36 no.2
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    • pp.125-134
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    • 2023
  • The Naedeokri and Nonggeori granites are early Proterozoic granites of the Taebaek-Sangdong area in the northeastern part of the Yeongnam Massif. In this paper, rare earth elements (REEs) concentrations of the minerals in Naedeokri and Nonggeori granites and Rb-Sr mineral isochron age are reported. Except zircon, the constituent minerals such as mica, feldspar, quartz, and tourmaline show LREE-enriched and HREE-depleted REE patterns with relatively large Eu negative anomaly. However, zircon has geochemical characteristic of LREE- and HREE-enriched REE pattern with large Eu positive anomaly. This pattern suggests that zircon should be hydrothermal zircon due to deuteric hydrothermal alteration. In addition, the Rb-Sr mineral age of Naedeokri granite indicates an age value of 1.814±142(2σ) Ma. The Rb-Sr whole rock age including pervious data of Naedeokri and Nogggeori granite indicates an age value of 1,707±74(2σ) Ma. This value is younger than the Sm-Nd isochron of 1.87 Ga, indicating that the Rb-Sr isotope system may be re-homogenized by hydrothermal alteration during the transition from a magmatic to a hydrothermal system.

Utilizing Abandoned Mines in Regional Development: Feasibility of Underground Data Centers and Public Sports Facilities (폐광지역발전을 위한 폐광산 활용방안 연구: 지하 데이터센터 및 공공체육시설로의 운용성 평가)

  • Hyeong-Geol Kim;Ganghui Kim;Sanghyun Bin;Won-Sik Woo;Jongmun Cha;Chang-Uk Hyun
    • The Journal of Engineering Geology
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    • v.33 no.4
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    • pp.737-753
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    • 2023
  • Abandoned mines represent unused space resulting from resource use and changes in industrial environments. Efforts are underway to repurpose such underground spaces, leveraging their unique attributes of temperature stability, shading, and security. This study aimed to assess the feasibility of operating high-demand data centers and public sports facilities as potential recycling options for abandoned mine spaces. The status of data centers located in abandoned mines abroad was examined, including their operational technology capitalizing on the advantages of underground spaces. Considering the varying sizes of underground spaces in different types of abandoned mine in South Korea, the suitability of installing facilities for 12 different sports was evaluated for potential contributions to the health and welfare of local residents. The utilization of abandoned mine spaces as data centers and public sports facilities is expected to not only recycle industrial heritage but also to allow new development opportunities for local communities.

A Study on Acoustic Emission and Micro Deformation Characteristics During Biaxial Compression Experiments of Underground Opening Damage (이축압축실험을 통한 지하공동 손상시 음향방출 및 미소변형 특성 연구)

  • Min-Jun Kim;Junhyung Choi;Taeyoo Na;Chan Park;Byung-Gon Chae;Eui-Seob Park
    • Tunnel and Underground Space
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    • v.34 no.2
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    • pp.169-184
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    • 2024
  • This study investigates acoustic emission (AE) and micro-deformation characteristics of circular openings through biaxial compression experiments. The experimental results showed a significant increase in the frequency, count, energy, and amplitude of AE signals immediately before damage occurred in the circular opening. The differences in frequency and count between before and after damage initiation were significantly pronounced, indicating suitable factors for identifying damage occurrence in circular openings. The results for digital image correlation (DIC) technique revealed that micro-deformation was concentrated around the openings, as evidenced by the spatial distribution of strain. In addition, spalling was observed at the end of the experiments. The AE and micro-deformation characteristics presented in this study are expected to serve as fundamental data for evaluating the stability of underground openings and boreholes for deep subsurface projects.