• Geotechnical Engineering
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• v.14 no.2
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• pp.107-126
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• 1998

Ground settlements induced by tunnel excavation cause the foundations of the neighboring building structures to deform. An expert system called NESASS( Neural network Expert System for Adjacent Structure Safety analysis) was developed to analyze the structural safety of such building structures. NESASS predicts the trend of ground settlements resulting from tunnel excavation and carries out a safety analysis for building structures on the basis of the predicted ground settlements. Using neural network technique. the NESASS learns the database consisting of the measured ground settlements collected from numerous actual fields and infers a settlement trend at the field of interest. The NESASS calculates the magnitudes of angular distortion, deflection ratio, and differential settlement of the structure. and in turn, determines the safety of the structure. In addition, the NESASS predicts the patterns of cracks to be formed in the structure, using Dulacska model for crack evaluation. In this study, the ground settlements measured from Seoul subway construction sites were collected and classified with respect to the major factors influencing ground settlement. Subsequently, a database of ground settlement due to tunnel excavation was built. A parametric study was performed to select the optimal neural network model for the database. A comparison of the ground settlement predicted by the NESASS with the measured ones indicates that the NESASS leads to reasonable predictions. The results of confidence evaluation for safety evaluation system of the NESASS are presented in this paper.

• Korean Journal of Construction Engineering and Management
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• v.11 no.2
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• pp.54-63
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• 2010

Domestic construction companies suffer from the difficulty in financing in the wake of economic slump at home and abroad. In the periods of this economic slump, which hit the nation REITs, the facilitator of fluid financing and the stimulating of construction economic, has increasingly been expanded since its introduction in 2001. But, REITs relatively falls behinds any other nations, in terms of its growth speed and marketing volume. The purpose of this research thesis is to suggest the method for composing a portfolio using Markowitz portfolio selection models for stimulating REITs. Main contents are as follows. First, the thesis made the comparative analysis on profit increase in REITs investment in application of models by Markowitz and REITs derivatives from 2007/07/03 to 2008/07/21 during investment analysis periods. The result showed that total profits by Markowitz model amounted to about 10 percent higher than average profits of REITs derivatives. Second, this thesis made the analysis on sensitivity of data-gathering and portfolio change periods of the existing profits, in order to measure the both periods and yield optimum profits. The six month data-collecting periods of profits accounted for some 16% higher profits than profits of REITs derivatives. In case when the two week periods of portfolio change accounted for some 11% higher profits than profits of REITs derivatives.

• Korean Journal of Construction Engineering and Management
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• v.10 no.1
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• pp.156-166
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• 2009

Residential land development projects are tending upwards recently. However, an indiscreet residential land development has tended to damage environment by destroying existing green lands and trees of target lands and generating many cut slopes with transformation of its topography. There are Prior Environmental Review(PER) for district designation and Environmental Impact Assessment(EIA) before approval on development plans. PER is implemented after developing a residential land development plan and EIA is implemented after completing a detail design. As the result, many of residential land development projects are passive to reduce potential environmental problems on the designated sites. Object of this study is to construct an evaluation system on alternatives in the early step of site designation for implementing residential land development projects with environment-friendly and sustainable way. For this, alternative evaluation model is constructed by using Fuzzy Inference and Analytic Hierarchy Process(AHP) method based on Environmental Evaluation Factors of residential land development project, which are proposed in the precedent research. If a decision maker evaluates environment damage by ten-point method, the point is transformed Environmental Performance(EP) by Fuzzy Inference, and then, applying weight that is already calculated by AHP method, Total Environmental Performance(TEP) is calculated. After all, an alternative with the highest TEP is selected as the best one. Using this evaluation system, more than two alternatives of residential land development project site, which can hold location appropriateness in the early under undecided land use plan, can be evaluated quantitatively. As environmental damages, which can be generated by implementing a residential land development project, can be detected in the early step, environmental damages can be removed or reduced at the source.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.1
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• pp.1-14
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• 2017

A land cover map provides basic information to help understand the current state of a region, but its utilization in the ecological research field has deteriorated due to limited temporal and spatial resolutions. The purpose of this study was to investigate the possibility of using a land cover map with data based on high resolution images acquired by UAV. Using the UAV, 10.5 cm orthoimages were obtained from the $2.5km^2$ study area, and land cover maps were obtained from object-based and pixel-based classification for comparison and analysis. From accuracy verification, classification accuracy was shown to be high, with a Kappa of 0.77 for the pixel-based classification and a Kappa of 0.82 for the object-based classification. The overall area ratios were similar, and good classification results were found in grasslands and wetlands. The optimal image segmentation weights for object-based classification were Scale=150, Shape=0.5, Compactness=0.5, and Color=1. Scale was the most influential factor in the weight selection process. Compared with the pixel-based classification, the object-based classification provides results that are easy to read because there is a clear boundary between objects. Compared with the land cover map from the Ministry of Environment (subdivision), it was effective for natural areas (forests, grasslands, wetlands, etc.) but not developed areas (roads, buildings, etc.). The application of an object-based classification method for land cover using UAV images can contribute to the field of ecological research with its advantages of rapidly updated data, good accuracy, and economical efficiency.

• The KIPS Transactions:PartA
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• v.9A no.2
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• pp.241-248
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• 2002

With the structure of tilde-area computing system which Is specified by a researching team in Vrije University, Netherlands, lots of researchers and developers have been progressing the studies of global location and interconnection services of distributed objects existing in global sites. Most of them halve focused on binding services of only non-duplicated computational objects existing wide-area computing sites without any consideration of duplication problems. But all of objects existing on the earth rave the duplicated characteristics according to how to categorize their own names or properties. These objects with the same property can define as duplicated computational objects. Up to now, the existing naming or trading mechanism has not supported the binding services of duplicated objects, because of deficiency of independent location service. For this reason, we suggest a new model that can not only manages locations of duplicated objects In wide-area computing environments, but also provide minimum binding time by considering both the optimal selection of one of duplicated objects and load balance among distributed systems. Our model is functionally divided into 2 parts, one part to obtain an unique object handle of duplicated objects with same property as a naming and trading service, and the other to search one or more contact addresses by a node manager using a liven object handle, as a location service For location transparency, these services are independently executing each other. Based on our model, we described structure of wide-area integrated tree and algorithms for searching and updating contact address of distributed object on this tree. finally, we showed a federation structure that can globally bind distributed objects located on different regions from an arbitrary client object.

• Korean Journal of Construction Engineering and Management
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• v.15 no.6
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• pp.26-34
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• 2014

Highway construction is a combination of linear, repetitive, and highly equipment intensive operations. Various types of construction equipment are deployed to ensure undisrupted performance of construction, and thus productivity improvement and cost-saving can be achieved through well-thought-out planning. The selection of construction equipment is dependent upon construction sequence, site conditions, and construction methods. In the process of planning, management should consider various types of construction methods per each type of construction operation. Also, management should map out proper construction equipment operation plan that takes the construction duration and cost measures into consideration. However, limited availability of historic data from the similar types of operations has been a stumbling block to proper construction planning, making the operations performed based upon experience and intuition guided by rules-of-thumb. As a consequence, the planing phase rarely provided an adequate validity in the implementation phase. The researchers developed a process logic for each construction type that management can utilize from early phase of highway construction planning process. Moreover, derived the construction equipment combination optimized for efficiency by using the process simulation technique. The developed method is expected to be useful for the decision-making process that aims to evaluate efficiency of various process plans and to ensure optimal selection of construction equipment for highway construction projects.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.3 s.33
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• pp.69-77
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• 2005

Most of the evaluations of environmental effect of construction of road do not run parallel with the evaluation of the propriety of the business, but it just reviews how to reduce contamination before the beginning of the construction work. This reveals the limitation of the induction of environment friendly development from the fundamental. In this study, a function of GIS spatial analysis for 9 elements of pre-evaluation of environmental effect has been introduced, and a GIS decision making system for environmental effect of a road has been established for an integrated evaluation by using individual evaluation result. By using GIS decision making system for pre-evaluation of environmental effect that has been developed in this study and the GIS data that has been collected, it would be possible to decrease time and money for evaluation as well as fulfill the requirement of objectivity. Therefore, it would be possible to apply for pre-evaluation of environmental effect when deciding on the route of the road at the beginning stage of the construction work. Also, through the system developed in this study, the construction body could easily induce a mutual agreement with the residents by the visual evaluation material, which might result in an evaluation of environmental effect while decreasing time and money at the beginning stage of the construction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.401-417
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• 2020

As an increasing demand for rapid railway transportation, the construction of sidetrack is inevitable to operate local and express trains simultaneously. However, the current technologies for the sidetrack construction method require a long construction period by interrupting the operation of the existing subway line, as well as cause a huge economic loss. Thus, it is necessary to study the sidetrack construction method under the special situation that the subway is in operation and to analyze the risk of the existing tunnel enlargement process for the sidetrack construction. Therefore, in this paper, the Government Complex Gwacheon station on Subway Line 4 was considered as a target station for the virtual sidetrack construction and the optimal sidetrack construction plan was derived. Subsequently, the application of risk management process was carried out in the order of identifying risk, risk response planning, performing a risk analysis, risk monitoring and control for potential risk events during the construction of sidetrack under the subway operation. A total of eight potential risk events and risk mitigation methods were selected, and a risk assessment matrix was established using the five-step risk probability and impact level criteria to perform the risk assessment including residual risks. Based on the results of the risk assessment, the risk grade and the reduction effect of each risk mitigation method were confirmed.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.391-398
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• 2003

Research was conducted to establish the leaf and petiole sap test to diagnose the nutritional status of tomato. The concentrations of $NO_3$, $PO_4$, K, Ca, Mg and $SO_4$ ions extracted from the leaves and petioles in the different positions in a plant were measured and compared with their corresponding inorganic contents in the leaves analyzed by the chemical method. The ionic concentrations in the leaf and petiole sap showed the different values depending on their positions in a plant. The leaves and petioles in the lower positions of a plant had higher concentrations of $NO_3$, Ca, Mg and $SO_4$ ions. In particular, there were greater changes of ionic concentrations and less increases in the leaf length and width from the 9th compound leaf down from the uppermost cluster. On the other hand, the leaflets in a compound leaf had the same ionic concentrations. Therefore, it appeared that the optimal sampling position of leaf and petiole for the sap test is the leaflets of the 9th compound leaf down from the uppermost cluster. A good correlation between the sap test and the chemical analysis of plant showed that the ionic concentrations in the leaf and petiole sap reflect the nutritional status of tomatoes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.2
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• pp.119-126
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• 1983

The purposes of this study are to analyze/model the mode choice behavior of the regional traveler by express bus/express train and to offer useful source in deciding the public transportation policy. The data analyzed were trips of both modes from March, 1980 to November, 1981, between Seoul and other nineteen cities; the data were grouped as five groups according to the change of service variables. Service variables were travel time(unit: minute), cost(:won), average allocation time(:won), service hour(:hour), and dummy variables by mode. As model Logit Model with linear or log utility function were postulated. As the result of this study, some reseanable models were constructed at Model Type I(eq. 2. of this paper) based on the above data except the dummy. It was judged that the parameters calibrated by Group III and Group IV data in table 4, were optimal. Among the parameters, the parameter of travel cost was most reliable. There was a tendency preferring express bus to train in October and November. With the constructed model and Pivot-Point Method. the demand change of express train caused by the service variables' change could be forecasted over 99%.