• Journal of Korea Port Economic Association
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• v.32 no.2
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• pp.91-103
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• 2016

The purpose of this study is to analyze the efficiency and productivity of domestic trucking transportation companies using DEA-CCR, BCC, and Malmquist indexes. Here, we analyze the top 14 domestic trucking transportation companies, based on cargo volume. The number of freight agents, trucks, and assets are used as input variables, and cargo volumes and sales are used as output variables. The efficiency of trucking transportation companies is examined using a DEA approach, and Malmquist indexes are applied to analyze productivity. According to the DEA results, the efficiency levels of the CCR, BCC, and scales for three companies (DMU 4, 5, and 10) are 1, indicating that these companies are operated efficiently. At the same time, the Malmquist indexes show that all companies have values smaller than 1, except for the period 2012-2013, indicating that their productivity decreased. Furthermore, the TECI indexes were all larger than 1, except for the period 2012-2013, indicating that the companies are efficient. Lastly, all TCI indexes are smaller than 1, except for the period 2012-2013, indicating regressing trends.

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.15-20
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• 2006

In this study, we had investigated several input factors and output factors, to maintain safety management, of domestic shipping companies, and then had analyzed the efficiency of performance of performance about each shipping companies' safety management system from 1998 year to 2004 year using DEA method As the result of analysis, the annual mean efficiency of total companies tended downward every year. Analysis was that the cause was increase of the cost of repairing ship, the cost of ship's stores and idle day of ship.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.144-150
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• 2013

A New Ag-pastes were developed for integrating the high efficiency mono-Si solar cell. The pastes were the mixture of 84 wt% Ag, 2 wt% glass frit, 11 wt% solvent of buthyl cabitol acetate, and 3 wt% additives. After fabricating the Ag-pastes by using a 3-roll mill, they were coated on a $SiN_x$/n+/p- stacks of a commercial mono-Si solar cell. And the post-thermal process was also optimized by varying the process conditions of peak temperature. The optimized solar cell efficiency on a 6-inch mono-Si wafer was 18.28%, which was the one of the world best performances. It meaned that the newly developed Ag-paste could be adopted to fabricate a commercial bulk Si solar cell.

• Earthquakes and Structures
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• v.12 no.3
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• pp.321-332
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• 2017

The reverse fault is a dangerous geological hazard faced by buried steel pipelines. Permanent ground deformation along the fault trace will induce large compressive strain leading to buckling failure of the pipe. A hybrid pipe-shell element based numerical model programed by INP code supported by ABAQUS solver was proposed in this study to explore the strain performance of buried X80 steel pipeline under reverse fault displacement. Accuracy of the numerical model was validated by previous full scale experimental results. Based on this model, parametric analysis was conducted to study the effects of four main kinds of parameters, e.g., pipe parameters, fault parameters, load parameter and soil property parameters, on the strain demand. Based on 2340 peak strain results of various combinations of design parameters, a semi-empirical model for strain demand prediction of X80 pipeline at reverse fault crossings was proposed. In general, reverse faults encountered by pipelines are involved in 3D oblique reverse faults, which can be considered as a combination of reverse fault and strike-slip fault. So a compressive strain demand estimation procedure for X80 pipeline crossing oblique-reverse faults was proposed by combining the presented semi-empirical model and the previous one for compression strike-slip fault (Liu 2016). Accuracy and efficiency of this proposed method was validated by fifteen design cases faced by the Second West to East Gas pipeline. The proposed method can be directly applied to the strain based design of X80 steel pipeline crossing oblique-reverse faults, with much higher efficiency than common numerical models.

• Journal of Soil and Groundwater Environment
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• v.26 no.6
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• pp.118-129
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• 2021

The sediment transportation caused by soil erosion due to rainfall-discharge in the large watershed scale plays critical role in human society. The relationship between rainfall-discharge-sediment transportation is depending on the start time of rainfall and end of rainfall but, the studies related with rainfall characteristics are insufficient. In this study, The Soil and Water Assession Tool (SWAT) model was used to study the relationship between rainfall-discharge-sediment transportation at the Sook river watershed which is monitored by the Ministry of Environment. To do this, first of all, the sensitivity analysis about model attributes was performed using monitored data. The accuracy analysis of SWAT model was conducted using the model's efficiency index (Nash and Sutcliffe model efficiency; NSE) and the coefficient of determination (R²). After that, it was studied what results could be obtained according to changes in rainfall timing and end points. In the result of discharge simulation, the modified rainfall values (sum of total rainfall starting time and end time) showed more high accuracy values (R²:0.90, NSE: 0.8) than original rainfall values (R²:0.76, NSE: 0.72). In the result of sediment transportation simulation, during calibration had more resonable results(R²:0.87, NSE: 0.86) than compared with original rainfall values (R²:0.44, NSE: 0.41). However, validation results of sediment transportation simulation showed low accuracy values compared with calibration results. This results maybe cause monitoring periods of sediment flow compared with discharge monitoring periods. Nevertheless, since rainfall characteristic plays critical rule in model results, continuous research on rainfall characteristic is needed.

• Journal of the Society of Disaster Information
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• v.20 no.2
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• pp.257-269
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• 2024

Purpose: The purpose of this study is to explain the pivotal role of the travel forecasting process in urban transportation planning. This study emphasizes the use of travel forecasting models to anticipate future traffic. Method: This study examines the methodology used in urban travel demand modeling within transportation planning, specifically focusing on the Urban Transportation Modeling System (UTMS). UTMS is designed to predict various aspects of urban transportation, including quantities, temporal patterns, origin-destination pairs, modal preferences, and optimal routes in metropolitan areas. By analyzing UTMS and its operational framework, this research aims to enhance an understanding of contemporary urban travel demand modeling practices and their implications for transportation planning and urban mobility management. Result: The result of this study provides a nuanced understanding of travel dynamics, emphasizing the influence of variables such as average income, household size, and vehicle ownership on travel patterns. Furthermore, the attraction model highlights specific areas of significance, elucidating the role of retail locations, non-retail areas, and other locales in shaping the observed dynamics of transportation. Conclusion: The study methodically addressed urban travel dynamics in a four-ward area, employing a comprehensive modeling approach involving trip generation, attraction, distribution, modal split, and assignment. The findings, such as the prevalence of motorbikes as the primary mode of transportation and the impact of adjusted traffic patterns on reduced travel times, offer valuable insights for urban planners and policymakers in optimizing transportation networks. These insights can inform strategic decisions to enhance efficiency and sustainability in urban mobility planning.

• Journal of Korean Institute of Industrial Engineers
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• v.32 no.3
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• pp.163-171
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• 2006

This paper considers a scheduling problem to minimize the sum of the associated scheduling (production/delivery times) cost and the delivery cost for an integrated system of a single production machine and various transportation vehicles with transportation mode selection allowed. Each transportation mode is provided with a fixed number of vehicles at the associated delivery time and cost. The proposed problem is characterized as being NP-hard. Some solution properties are also characterized. Therewith, three heuristic algorithms (called SPT-based, LWF-based and WSPT-based heuristic) and a branch-and-bound algorithm are derived. In order to evaluate the effectiveness and efficiency of the proposed algorithms, computational experiments are made with some numerical instances.

• IE interfaces
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• v.16 no.1
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• pp.44-53
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• 2003

Ready-Mixed Concrete transportation business has been managed by the manual operation and intuitive decision making. This study is on the process improvement on ordering process, and allocation/transportation of trucks commuting between the batching plant and construction sites. Processes of order collection, job dispatch and allocation, and on-time-delivery are analysed and improved. The logistics control system, with GPS system, was developed and implemented based on the reconstructed processes. Performances are evaluated after improved business process and logistics system was applied, and it is shown that waiting time loss is decreased by 55%, and that efficiency is increased by 15%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.200-201
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• 2022

Off-Site Construction is being widely adopted as an alternative to solve endemic problems in construction industry such as low productivity and efficiency. However, it is strongly recommended to examine the transportation process to be optimized because it determines the size of a modular and influences the cost of the construction. Therefore, in this study simulation model for optimization of modular construction transportation plan was developed using AnyLogic. As a result of the study, the influence of trailer transport capacity and transport time increases as the number of modular which should be transported from factory to site increases.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.75-76
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• 2023

The construction industry's lack of experience and expertise makes it difficult for projects to realize the full benefits of implementing modular construction. Such project performance-hindering elements are often labeled as modular challenges. The added requirement for the transportation of the finished volumetric module is one aspect of the 'module transportation logistics,' the under-researched modular challenge that can prevent projects from incurring maximum cost and productivity benefits. The typical module transportation phases include lifting, transporting, and offloading. From conducting a literature review, this paper aims to investigate the equipment commonly adopted to lift and offload the module and validate its economic efficiency by comparing it with the alternative lifting/offloading equipment used in the two case projects. The results showed that hydraulic jacks are an economic alternative to the crane for lifting/offloading the module. The increase in single-module projects with smaller budgets made crane usage economically undesirable, and this study suggested a viable option for a more economical alternative.