• Tunnel and Underground Space
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• v.29 no.6
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• pp.379-393
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• 2019

For the economical construction of a tunnel by TBM, the selection of TBM optimized with the various project conditions is important, and also necessary to predict the performances of selected TBM in advance. This study was conducted to comprehensively evaluate the performance of the EPB shield TBM screw conveyor by the discrete element method. The sticky particles were used for the excavated material models, and screw conveyor with 11 different inclined angles were simulated to evaluate the performance depending on the different inclined angles. The four different rotational speed conditions of the screw were used, and torque, required power, extra energy for muck discharge, and the muck discharge rate were selected as four performance indicators. As a result, the optimized inclined angle was selected, and selected angle accords with the fact that EPB shield TBM screw conveyor is generally installed and adjusted at the inclined angle between 20.0° and 30.0° in the field.

• Journal of Digital Convergence
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• v.19 no.1
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• pp.167-176
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• 2021

Incheon Port urgently requires designation of a free trade zone to pursue development linked with the port hinterland while promoting continuous growth of the port. This study aims to evaluate the optimal location and derive policy implications for the designation of a free trade zone and analyzed factors property divided by groups. This study used the Consistent Fuzzy Preference Relation (CFPR) analysis technique to derive a practical construction direction by quantifying and evaluating linguistic measures. As a result, the Incheon New Port hinterland showed the highest location competitiveness among the four candidate areas of Incheon New Port hinterland, Aam Logistics Complex 2, North Port hinterland, and Gyeongin Port hinterland. Among the eight evaluation factors consisting of qualitative and quantitative factors, the Incheon New Port hinterland ranked no. 1 in all the four qualitative factors and one quantitative factor and received the highest total score. Also, Group 1 presented 'possibility to attract tenant companies' as first. Group 2 was 'complex size' and Group 3 was also 'possibility to attract tenant companies'. This study has the implication for suggesting the factors and evaluation structure of Free Trade Zone. Future research requires detailed empirical studies, such as expanding the subject of study or selecting factors that reflect the interests of each group.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.1
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• pp.135-143
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• 2010

The national base map has its value sand roles as the basic spatial information of the nation. The current national base map that is a 1/5,000 digital map, however, has failed to perform its roles as basic spatial information due to the limitations with its quality and accuracy and requires measures to complement them. Thus this study set out to suggest ways to advance the current 1/5,000 national base map, selected topography and natural features of a digital map that could be made with GSD 0.25m digital aerial photographs, and set up the optimal ways to make a digital map by conducting an experiment of making an optimal digital map with such photographs. It also analyzed the map made with GSD 0.25m digital aerial photographs for accuracy and usability. In order to establish a set of criteria of making a digital map with GSD 0.25m digital aerial photographs, the investigator carried out analyses and picked topography and natural features items, which include 9 large categories, 31 medium categories, and 509 small categories. Then an experiment of making a digital map was conducted according to the digital map making method. As a result, solid drawing was selected as the optimal way to making a digital map, and the optimal process was established. Using the research achievements, a model digital map was made with GSD 0.25mm digital aerial photographs. The map recorded about two times horizontal and vertical location accuracy than the old 1/5,000 digital map and was capable of detailed descriptions of topography and natural features. A new national base map made with GSD 0.25m digital aerial photographs will provide reliable spatial data, thus increasing the level of satisfaction among people and the level of advancement of national base maps.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.2
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• pp.83-94
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• 2010

The objective of this study was to determine the best probability distributions of annual, seasonal and monthly precipitation in Korea. Data observed at 32 stations in Korea were analyzed using the L-moment ratio diagram and the average weighted distance (AWD) to identify the best probability distributions of each precipitation. The probability distribution was best represented by 3-parameter Weibull distribution (W3) for the annual precipitation, 3-parameter lognormal distribution (LN3) for spring and autumn seasons, and generalized extreme value distribution (GEV) for summer and winter seasons. The best probability distribution models for monthly precipitation were LN3 for January, W3 for February and July, 2-parameter Weibull distribution (W2) for March, generalized Pareto distribution (GPA) for April, September, October and November, GEV for May and June, and log-Pearson type III (LP3) for August and December. However, from the goodness-of-fit test for the best probability distributions of the best fit, GPA for April, September, October and November, and LN3 for January showed considerably high reject rates due to computational errors in estimation of the probability distribution parameters and relatively higher AWD values. Meanwhile, analyses using data from 55 stations including additional 23 stations indicated insignificant differences to those using original data. Further studies using more long-term data are needed to identify more optimal probability distributions for each precipitation.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.4
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• pp.210-221
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• 2022

In order to promptly respond to disasters, the era of new spaces has opened where satellite images with various characteristics can be used. As the number of satellites in operation at home and abroad increases and the characteristics of satellite sensors vary, it is necessary to find satellite images optimized for disaster types. Disaster types were divided into typhoons, heavy rains, droughts, forest fires, etc., and the optimal satellite images were selected for each type of disaster considering satellite orbits, active/passive sensors, spatial resolution, wavelength bands, and revisit cycles. Each satellite orbit TLE (Two Line Element) information was applied to the SGP4 (Simplified General Perturbations version 4) model to develop a satellite orbit simulation algorithm. The developed algorithm simulated the satellite orbit at 10-second intervals and selected an accurate observation area by considering the angle of incidence of each sensor. The satellite orbit simulation algorithm was applied to the case of Typhoon Mitag in 2019 and compared with the actual satellite list. Through the analyzed results, the time and area of the captured image and the image to be recorded were analyzed within a few seconds to select the optimal satellite image according to the type of disaster. In the future, it is intended to serve as a basis for building a system that can promptly request and secure satellite images in the event of a disaster.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.685-693
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• 2015

There have been high demands for urban underground structures. However, they should be rapidly constructed while maintaining the functions of adjacent structures and road systems especially in urban areas. In this respect, trenchless excavation methods are considered to very effective in minimizing ground displacements during excavation works. A variety of field conditions such as economic, technical and environmental aspects should be taken into consideration when an optimum trechless excavation method is to be chosen in a given condition. Therefore, this study aims to carry out a fundamental study to select an optimum trenchless excavation method by the decision making technique. Especially, AHP (Analytic Hierarchy Process) which is a kind of a multiple attribute decision making process is adopted to consider the opinions of experts and to derive reliable decision criteria. As a result, the weights of key factors and the most effective trenchless methods for different ground conditions were proposed in this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5D
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• pp.477-483
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• 2010

The existing mass transport system, with its limited capacity and the saturated road networks, has given cause for a new means of transport to be developed, and strong demands for such new means of transport are observed more than ever. However, the traffic authority is seeking a new transport system that focuses more on LRT(Light Rail Transit), a downsized version of the existing urban railroad, rather than one that is appropriate to solve the traffic problems. Moreover, local governments are experiencing difficulties in planning their own mass transportation(bus or urban railroad) as they have no specified criteria for selecting a mass transport system. Accordingly, there has been an increasingly loud voice that calls for criteria to determine which mass transport system befits each transportation corridor. This paper develops a mass-transport demand forecasting model based on the GIS Buffering analysis of each transportation corridor in the city, sets up the capacity for each mass transport system and presents the criteria for selecting an optimal mass transport system for each transportation corridor. It also presents a methodology that identifies necessary and sufficient conditions for selection and evaluation, since it is most important to select the optimal mass-transport system that can meet the demand by each mass-transportation corridor.

• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.273-284
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• 1999

In order to develop star trackers for a satellite in our country we studies selection procedure of optical parameters. For logical selection of the optical parameters, we simulated the entire processes in which star lights imaged on a CCD sensor were read into and processed in an associated electronics. The simulation resulted in relations between star's magnitude and achievable pointing accuracy, from which we derived optimal optical parameters to satisfy a required pointing accuracy of a star tracker. The selected optical parameters were used in an optical system design of a star tracker with a pointing accuracy of 10 arcsec.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1412-1417
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• 2012

Building new town 'Pangyo', it is proposed to estalbish a memorial park. But memorial parks are considered as a 'disliked' facilities among people, so its location selection is very difficult to decide. In this study the location possibility is reviewed in two steps through interview with professionals. For selection a location, many components are also checked and evaluated such as natural conditions, technical points and social factors. This study can be helpful to study more location selection for other 'disliked' facilities.

• Journal of Navigation and Port Research
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• v.32 no.8
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• pp.621-628
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• 2008

Container terminals keenly compete with one another because of the continuous increase of container flows and the appearance of large-sized vessels. Major cargo handling equipment manufacturers are interested in the development of new conceptual equipment to greatly increase its productivity. In this study, a two-phase procedure is suggested for selecting the optimal development alternatives, when various development alternatives for container cranes are given. The first phase removes the alternatives that violate essential requirements and the second phase selects final alternatives by the evaluation of experts and the linear assignment method. Finally, a case applying the procedure is provided.