• Title/Summary/Keyword: 등급화 분석

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Estimating and Analyzing the Appropriate Pressing Force of the Rock Cutting Splitting Method (암반 커팅 스플리팅 공법의 적정 압입력 추산을 위한 분석해)

  • Lee, Sang-Min;Kim, Mun-Gyu;Cho, Jung-Woo;Yu, Sang-Hwa
    • Tunnel and Underground Space
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    • v.31 no.6
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    • pp.415-427
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    • 2021
  • This technical report briefly introduced the rock cutting splitting method under development. This method is a method of excavating the rock by splitting the block after the rock cutting process. After designing the cutting geometry of the rock face, the chisel is press-fitted to remove the rock block. At this time, when the cutting block is properly designed, the tensile crack propagates smoothly at the bottom of the rock block. An analytical solution was devised to estimate the indentation force required for splitting rock blocks using fracture toughness mode 1 required for tensile crack growth. The impact force of the hydraulic breaker of the excavator was analyzed, and the grade of the excavator that can be constructed according to the rock block design geometry was analyzed.

A Study on the Validity of the Technology Appraisal Model through the Analysis of the Business Performance and Technology Appraisal Items (기술금융기업의 경영성과와 기술력 평가항목 간 분석을 통한 기술력 평가모형의 타당성 연구)

  • Jun-won Lee
    • Information Systems Review
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    • v.22 no.1
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    • pp.73-89
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    • 2020
  • This study started to identify the "Forward-looking" of the technology appraisal model introduced to diversify financing methods of SMEs and improve financial accessibility. The multivariate regression analysis was performed by setting the business performance(growth, profitability, and stability) of technology financing companies as dependent variables, technology appraisal items as independent variables, number of employees, age of the company, asset and the Korea Standard of Industry Classification related to firm size and industry characteristics as control variables. As a result of the analysis, the technology appraisal items did not explain the profitability of the company significantly and had a limited explanatory power on growth potential. However, in terms of stability, we confirmed that R&D capacity is a significant variable explaining the debt ratio of technology financing companies. Therefore, it is concluded that the 'Forward-looking' reflection on the growth and profitability of the company should be strengthened in the future adjustment of the technology appraisal model and the development of the technology appraisal model for investment.

Analysis of Ground Behavior applied to the Design of Underground Opening Structures (지하공동구조물의 설계시 적용되는 지반거동해석)

  • 박남서;이성민
    • Explosives and Blasting
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    • v.15 no.1
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    • pp.44-60
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    • 1997
  • The design of underground cavern is basically governed by the mechanical properties of ground mass distributed around excavation. It is seldom possible to consider all the factors of ground mass properties in the evaluation of ground mass behavior as well as to classify those factors to a simple category. Until computer sciences have developed to calculate complex and laborious mechanical simulation of underground openings, ground behavior was quantitatively and qualitatively evaluated using empirical classification system. In this paper, analysis methods of ground behavior for underground cavern using the prediction of loosening zone, empirical method derived from rock mass classification and element stress analysis are described with chronological sequence.

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The application of simplified risk assessment for tunnel (터널 리스크 평가 기법의 적용성에 대한 연구)

  • Kim, Sang-Hwan;Lee, Chung-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.1
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    • pp.63-74
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    • 2007
  • Unexpected ground conditions have always been a major problem for the construction of tunnel. Therefore, it is necessary to evaluate the risk capacity before and/or during construction of new tunnel. This paper presents the simplified risk assessment system using modified stability number (N), namely Underground Risk Index (URI) system, to evaluate the tunnel risk possibility in the design stage. URI is a scoring system for risk possibility by rating the each appraisal elements. The modified stability number (N) which is one of risk factor in the Interaction Matrix parameters such as RQD, UCS, weathering, overburden, stability number, ground water-table, RMR, permeability and so on, is used in the system. In addition, the case study is performed in order to verify the applicability of URI-system in practice.

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Analysis of Ground Behavior applied to the Design of Underground Opening Structures (지하공동구조물의 설계시 적용되는 지반거동해석)

  • 박남서;이성민
    • The Journal of Engineering Geology
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    • v.1 no.1
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    • pp.38-53
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    • 1991
  • The design of underground cavern is basically governed by the mechanical properties of ground mass distributed around excavation. It is seldom possible to consider all the factors of ground mass properties in the evaluation of ground mass behavior as well as to classify those factors to a simple category. Until computer sciences have developed to calculate complex and laborious mechanical simulation of underground openings, ground behavior was quantitatively and qualitatively evaluated using empirical classification system. In this paper, analysis methods of ground behavior for underground cavern using the prediction of loosening zone, empirical method derived from rock mass classification and element stress analysis are described with chronological sequence.

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Quantification and Evaluation of Groundwater Quality Grade by Using Statistical Approaches (통계적 분석 방법을 이용한 국가지하수수질측정망의 오염 등급 정량화 및 평가)

  • Yoon, Hee-Sung;Bae, Gwang-Ok;Lee, Kang-Kun
    • Journal of Soil and Groundwater Environment
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    • v.17 no.1
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    • pp.22-32
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    • 2012
  • This study suggests a method to grade groundwater quality quantitatively using statistical approaches for evaluating the quality of groundwater in wells included in the Groundwater Quality Monitoring Network (GQMN). The proposed analysis method is applied to GQMN data from 2001 to 2008 for nitrate nitrogen, chloride, trichloroethylene, potential of hydrogen (pH), and electrical conductivity. The analysis results are obtained as groundwater quality grades of the groundwater representing each of the monitoring stations. The degree of groundwater contamination is analysed for water quality parameters, district, and usage. The results show that the degree of groundwater contamination is relatively high by nitrate nitrogen, bacteria and electrical conductivity and at Seoul, Incheon, Gwangju, Gyeonggido and Jeollado. The degree of contamination by nitrate nitrogen and trichloroethylene is especially high when the groundwater is used for agricultural and industrial water, respectively. It is evaluated that potable groudnwater in GQMN is significantly vulnerable to nitrate nitrogen and bacteria contamination.

Experimental Study on Fatigue Strength of Slip-Critical Splices using F13T High Strength Bolts (F13T급 고장력볼트를 이용한 마찰연결부 피로강도에 관한 실험적 연구)

  • Han, Jong Wook;Park, Young Suk
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.5A
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    • pp.623-629
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    • 2008
  • New high strength bolts are required due to the development of the high strength steel, the ultra-thick steel plates, and the long-span bridge, though high strength bolts with tensile strength of 1,000 MPa are mainly used in construction site of every country. Consequently, in this study, we estimated the fatigue strength by performing fatigue test of slip-resistant splices with slip coefficients applying the newly developed F13T high strength bolts. The fatigue test satisfied the Category B requirements with the fatigue strength of slip-resistant splices. Also we analyzed the fatigue fracture characteristics of slip-resistant splices.

A Study on the Habitat Use of Waterbirds and Grading Assessment of the Tidal Flat at Muan Bay in Jeollanamdo, Korea (전라남도 무안만에 도래하는 수조류의 서식지 이용 및 갯벌등급 평가)

  • Kang, Tae-Han;Yoo, Seung-Hwa;Lee, Si-Wan;Choi, Ok-In;Lee, Chong-Bin
    • Korean Journal of Environment and Ecology
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    • v.22 no.5
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    • pp.521-529
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    • 2008
  • This research conducted a survey on waterbirds visiting this area four times by season from February to October in 2007 to look into the habitat use of waterbirds, to do a value and grade testing of the tidal flat by dividing the foreshore on Muan Bay located in Jeollanam-do into four areas (Dongam, Guro, Bokryong and Wangsan tidal flats). The survey results revealed that there existed a total of 15,755 individuals of 54 species including 2 species of grebes, 7 species of herons, 7 species of dabbling ducks, 6 species of diving ducks, 20 species of waders, 3 species of gulls and 9 other species and this survey also observed 9,291 individuals of the wading birds as a dominant group on Muan Bay. In these classified groups, the gulls and waders were observed to mostly use Dongam tidal flat as their habitat, while the group using Guro tidal flat as their habitat was mostly grebes, dabbling and diving ducks. As a result of UPGMA clustering analysis in consideration of the species and number of individuals, there appear the close similarities between Dongam and Bokryong tidal flats and so do Guro and Wangsan tidal flats. Taking a look at the grading of tidal flats by setting up ecological indexes, such as diversity index, abundance index, and dominance index, etc. legally reserved species and maximum number of individuals as a standard, the rank for the value and importance degree of Bokryong tidal flat appeared higher than that of the other three tidal flats. Like this, the gradation of tidal flats according to waterbirds are judged to able to suggest objective data on the issue of proper judgment and designation of valuable tidal flat areas and its subsequent effective preservation and management.

Vascular Plant Diversity and Vegetation of Samusan Mt. in Jecheon-si, Korean Peninsula (사무산(제천시)의 식물다양성과 식생)

  • Kim, Jung-Hyun;Kim, Jin-Seok;Nam, Gi-Heum;Jung, Eun-Hee;Lee, Kyeong-Ui;Hwang, Yo-Seob
    • Korean Journal of Plant Resources
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    • v.31 no.4
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    • pp.396-418
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    • 2018
  • This study was carried out to investigate the flora and the vegetation of Samusan mountain on Jecheon-si, located in the middle part of the Korean peninsula. The vascular plants which were collected in 9 times from June 2014 to October 2015 were identified as 502 taxa in total, including 102 families, 314 genera, 445 species, 6 subspecies, 49 varieties, 1 form and 1 hybrid. The largest families were as follows; Asteraceae (70 taxa), Poaceae (52 taxa), Rosaceae (30 taxa), Fabaceae (28 taxa), and Cyperaceae (20 taxa). Of them, Korean endemic plants numbered 10 taxa, and vascular plants listed in the red data according to the International Union for Conservation of Nature (IUCN) numbered 14 taxa. The floristic regional indicator plants found in this area were 61 taxa in total. Among them, 5 taxa revealed the floristic grade V, 11 for floristic grade IV, 14 for floristic grade III, 10 for floristic grade II, and 21 for floristic grade I. The alien plants were identified as 43 taxa and the percentage of naturalized index (NI) was 8.6%, and urbanization index (UI) was 13.4%, respectively. Samples of the forest vegetation on the Samusan Mt. were mainly classified as Pinus densiflora, Quercus variabilis, Q. acutissima, Q. mongolica, Zelkova serrata and Robinia pseudoacacia forest. The vertical structures of the forest were stable and the DBH-Class analyses showed that the dominant tree species would be maintained. In the surveyed areas, high plant diversity was shown, and a number of endemic, rare, calcicole plants and phytogeographically important plants were found. Nonetheless, numerous and diverse biological resources native have been consistently disturbed or damaged by human activities without some form of protection. Therefore, it is needed to set up strategies for conservation forest vegetation in this study area.

Mineralogical and Drying Characteristics of Chinese Low Rank Coal for Coal Gasification (석탄가스화를 위한 중국산 저급 석탄의 광물학적 및 건조 특성)

  • Park, Chong-Lyuck;Kim, Byoung-Gon;Jeon, Ho-Seok;Kim, Sang-Bae;Park, Suk-Hwan;Lee, Jae-Ryeong
    • Journal of the Mineralogical Society of Korea
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    • v.23 no.3
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    • pp.199-209
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    • 2010
  • Coal gasification technology in the sector of domestic clean coal technologies is being into the limelight since recent dramatic rise of international oil price. In this study, we used a low rank coal from Inner Mongolia, China as a starting material for gasification. Various properties including optical, mineralogical, X-ray spectroscopic, X-ray diffraction, and drying property were measured and tested in order to estimate the suitability of the coal to gasification. The coal was identified as a brown coal of lignite group from the measurement of vitrinite reflectance. The coal has very low slagging and fouling potentials, and the ignition temperature is about 250C. The major impurities consist of quartz, siderite, and clay minerals. Additionally, the coal had moisture content above 28%. Tests for finding effective drying method showed that the microwave drying is more effective than thermal drying.