• Tunnel and Underground Space
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• v.24 no.1
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• pp.67-80
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• 2014

Long-term stability and delayed failure of granite were evaluated through the laboratory test based on Wilkins method and Brazilian disc test (BDT) which yields tensile strength, mode I fracture toughness and subcritical crack growth parameters. Then, the long-term strength of granite was estimated by using analytical models and long-term stability of compressed air-energy storage (CAES) pilot cavern pressurized up to 5 ~ 6 MPa was evaluated using numerical code, FRACOD with the determined subcritical crack growth parameters. The results of test and analyses showed that the subcritical crack growth index, n was determined as 29.39 and the inner pressure of 5 ~ 6 MPa had an insignificant effect on the long-term stability of pilot cavern. It was also found that the measurement and analysis of acoustic emission events can describe the accumulation of damage due to subcritical crack growth quantitatively. That is, AE monitoring can provide the current status of rock under loading if we make an identical installation condition in the field with that of the laboratory test.

• The korean journal of orthodontics
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• v.31 no.4 s.87
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• pp.393-401
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• 2001

The purposes of this study were to assess the treatment results in orthodontic department, Kyung Hee University, to evaluate the occlusion at 2 year follow-up control, in relation to the original malocclusion, and changes occurring in the follow-up period, and to determine whether treatment and posttreatment changes of the PAR index were related to the original Angle classification Dental study casts of 25 patients in permanent dentition were evaluated using Peer Assessment Rating (PAR) index. The PAR index was measured at the pretreatment stage, immediately after treatment, and at 2 yews posttreatment. The following results were obtained : 1. The treatment reduced the PAR index by 85.05% and it indicates that KHDC clinic has a high standard of treatment 2. The follow-up result of 75.40% PAR score reduction implies a gain of 9.55% of posttreatment PAR score during follow-up period. 3. There is no relationship between the treatment changes of the PAR index and the orignal Angle classification.

• Korean Journal of Environment and Ecology
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• v.3 no.1
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• pp.28-41
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• 1989

A survey of Hongryu-Dong and Chi-in district. Gaya National Park, was conducted using 40 sample sites of 500$m^2$ size. TWINSPAN classification confirmed a complex pattern of both local and geographical variation in the vegetation: Dry and wet community types. Within dry community types, two floristic assocation of Pinus densiflora were defined according to local variation. Within wet community types. two floristic association were defined according to altitude. Those associations can be further subdivided floristically into eight subassociation. The vegetation pattern presented by DCA ordination corresponds to one of TWINSPAN at the first two division. The DCA ordination was successful in separating Pinus densiflora from broad leaf forest. Ordination of samples produced arrangements reflectly environmental gradient of soil. The correlation between the first axe of DCA and soil moisture, soil acid, altitude, maximum species diversity and species diversity was significantly negative. The similarity index between each community was very low level.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.674-679
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• 2006

The public research and development (R&D) funds for construction engineering is one of the key elements for the advancement of construction industry. Korean Ministry of Construction and Transportation is currently planning to produce approximately US$ 500 millions of research funds every year in Korea from year 2007. Along with the prospect for increasing R&D investment, there is of increasing pressures on the development of quantitative methodologies for assessing the performance of construction R&D results. Although there have been some general R&D project evaluation methods, they are not readily used for construction R&D research assessment due to the distinct characteristics of construction R&D. This paper presents a simple methodology that can make quantitative assessments of construction R&D performances. The proposed methodology is expected to assist government officials in objectively evaluating construction R&D performances and identifying the areas that require more R&D investment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.30-39
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• 2022

Maintaining structural integrity of major apparatuses in a nuclear power plant, including piping system, is recognized as a critical safety issue. The integrity of piping system is also a critical matter related to the safety of a nuclear power plant. The actual failure mode of a piping system due to a seismic load is the leakage due to a fatigue crack, and the structural damage mechanism is the low-cycle fatigue due to large relative displacement that may cause plastic deformation. In this study, in-plane cyclic loading tests were conducted under various constant amplitudes using specimens composed of steel straight pipes and a steel pipe tee in the piping system of a nuclear power plant. The loading amplitude was increased to consider the relative displacement generated in the piping system under seismic loads, and the test was conducted until leakage, which is the limit state of the steel pipe tee, occurred due to fatigue cracks. The limit state of the steel pipe tee was expressed using a damage model based on the damage index that used the force-displacement relationship. As a result, it was confirmed that the limit state of the steel pipe tee can be quantitatively expressed using the damage index.

• Korean Journal of Construction Engineering and Management
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• v.11 no.6
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• pp.78-88
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• 2010

Since the larger and complex construction projects are performed, project performance measurement is highlighting the importance to eliminate inefficiencies and plan to reasonable management practices. So many researchers are conducting research about the project critical sucess factor. But, these factors are mixed both management practices to improve performance and native project characteristics. Therefore performance measurement data couldn't apply to another project successfully. And the project characteristics affect project performance. But contractor couldn't change characteristics. This study provides a project characteristics's definition and classification. This study provides a quantitative level of performance improvement difficulty through out project manager survey. The contractor can estimate a level of performance difficulty through initial project information. With this, project contractor can more efficiently manage project.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.4
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• pp.86-101
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• 2019

Remote sensing technology has been continuously developed both quantitatively and qualitatively, including platform development, exploration area, and exploration functions. Recently, the use cases and related researches in the agricultural field are increasing. Also, since it is possible to detect and quantify the condition of cropland and establish management plans and policy support for cropland and agricultural environment, it is being studied in various fields such as crop growth abnormality determination and crop estimation based on time series information. The purpose of this study was to analyze the vegetation index for agricultural land reclamation area using a UAV equipped with a multi-spectral sensor. In addition, field surveys were conducted to evaluate the accuracy of vegetation indices calculated from multispectral image data obtained using UAV. The most appropriate vegetation index was derived by evaluating the correlation between vegetation index calculated by field survey and vegetation index calculated from UAV multispectral image, and was used to analyze vegetation index of the entire area.

• Journal of Korea Water Resources Association
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• v.39 no.2 s.163
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• pp.161-178
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• 2006

Heathcote (1998) identified a systematic, seven-step approach to general watershed planning and management. It consists of 1) understanding watershed components and processes, 2) identifying and ranking problems to be solved, 3) setting clear and specific goals, 4) developing a list of management options, 5) eliminating infeasible options 6) testing the effectiveness of remaining feasible options, and 7) developing the final options. In this study the first five steps of that process were applied to the Anyangcheon watershed in Korea, which experiences streamflow depletion, frequent flood damages, and poor water quality typical of highly urbanized watersheds. This study employed four indices: Potential Flood Damage(PFD), Potential Streamflow Depletion(PSD), Potential Water Quality Deterioration(PWQD) and Watershed Evaluation Index(WEI) to identify and quantify problems within the watershed. WEI is the integration index of the others. Composite programming which is a method of multi-criteria decision making is applied for the calculation of PSD, PWQD and WEI (Step 2). The primary goal of the study is to secure instreamflow in the Anyangcheon during dry seasons. The second management goals of flood damage mitigation and water quality enhancement are also set (Step 3). Management options include not only structural measures that can alter the existing conditions, but also nonstructural measures that rely on changes in human behavior or management practices (Step 4). Certain management options which are not technically, economically, and environmentally feasible, are eliminated (Step S). Therefore, this study addresses a Pre-feasibility study, which established a master plan using Steps 1 through 5.

• Journal of Internet Computing and Services
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• v.15 no.6
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• pp.35-45
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• 2014

Due to the spread of unreliable online information on the social network services, the users are faced with a difficult problem for determining if the information is trustworthy or not. At present, the users should make a decision by themselves throughly for the trustworthiness of the information. Therefore, we need a way to systematically evaluate the trustworthiness of information on the social network services. In this paper, we design a trust index, called KTI (Korean Trust Index for SNS), as a criterion for measuring the trust degree of the information on the social network services. Using KTI, the users are readily able to determine whether the information is trustworthy. Consequently, we can estimate the social trust degree based on the variation of KTI. This paper derives the various factors affecting trust from the properties of the social network services, and proposes a model to evaluate the trustworthiness of information that is directly produced and distributed over the online network. Quantifying the trust degree of the information on the social network services allows the users to make efficient use of the social network.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.274-283
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• 2019

Beta diversity is an efficient means of assessing the spatial variation in community composition among sites. To present fish community variation and LCBD (Local Contribution to Beta Diversity) among sites in stream, 6 sampling sites were selected in Cheonggye stream. Fish communities, environmental and habitat variables were collected at sites from April 2014 to October 2015. We used the total variance of the fish community data table (site-by-species community table) based on different forms, presence-absence, abundance, and Hellinger transformation, to estimate and compare beta diversity and LCBD. Fish community data table transformed by Hellinger distance showed the higher values of beta diversity than presence-absence and abundance data table. A similar patterns of LCBD were observed with presence-absence and Hellinger transformed data table. Low value of beta diversity calculated by community data table with abundance was due to the non-normality of fish assemblage data. Additionally, correlation coefficients were calculated to evaluate the relationships among LCBD, community indices and physicochemical variables. LCBD showed negative correlation coefficients with Shannon diversity. Overall, application of beta diversity analysis is an efficient method of addressing spatial variation of fish communities and ecological uniqueness of the sites in stream.