• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1055-1067
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• 1994

This paper is presented to perform linear dynamic analysis of bridges due to vehicle moving on bridges. The road surface roughness and bridge/vehicle interaction are also considered. The bridge and vehicle are modeled as 3-D bridge and vehicle model, respectively. The road surface roughness of the roadway and bridge decks are generated from power spectral density(PSD) function for good road. The PSD function proposed by C.J. Dodds and J.D. Robson is used to describe the road surface roughness for good road condition. The vehicles are modeled as two nonlinear vehicle model with 7-D.O.F of truck and 12-D.O.F of tractor-trailer and the equations of motion of the vehicles are derived using Lagrange's equation. The main girder and concrete deck are modeled as beam and shell element, respectively and rigid link is used between main girder and concrete deck. The equations of motion of the vehicles are solved by Newmark ${\beta}$ method and the equations of the motion of the bridges are solved by mode-superposition procedures. The validity of the proposed procedure is demonstrated by comparing the results with the experimental data reported by the AASHO Road Test. The comparison shows that the agreement between experiment and theory is quite satisfactory.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.163-172
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• 2011

The CFTA girder developed is a concrete filled steel tubular system with arched shape and external post-tensioning (PT) tendons which control the initial camber and the bending stress of the girder. In the present study the effects of the PT tendons on the dynamic behavior of the girder subjected to a moving vehicle load are numerically investigated. Various levels for the tendon quantity and the tendon forces are considered, using the existing FE model of the girder. The vehicle considered is a DB-24 truck and is modeled with two tracks-three axles. Equivalent-load pulse time histories are applied to each node to simulate the moving vehicle, depending on the time of arrival and the discretization. The vehicle speeds are varied from 40 km/hr to 100 km/hr with increment of 20 km/hr. The analysis results show that the tendon forces do not produce any influences on the dynamic responses of the girder. However the dymamic deflection of the girder increases when a smaller amount of tendons is used. The Dynamic Amplification Factors (DAF) are evaluated based on the static and dynamic responses. Much lower values of the DAF are obtained, even no tendons applied, than those provided by the design criteria of the AASHTO LRFD and the Korea Highway Standard Specification.

• Fire Science and Engineering
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• v.33 no.3
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• pp.138-142
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• 2019

By securing golden time, this study analyzed the effects of an emergency vehicle priority system in Cheongju, North Chungcheong province. Until the scene of a fire is reached, severe obstacles in the street, such as traffic congestion, cars coming forward, non-cooperative vehicles etc., are significant. To solve these problems of road obstacles, it is essential to adopt an emergency vehicle priority system. From April 2017 to June 2018 (1 year and 2 months, 426 days), the dispatch time and date, fire truck moving distance and required time, traffic signal control section and pass time, and shortening time, were measured. This study selected 140 cases consisting of five heavy traffic and frequent dispatch routes out of 293 cases. The effects of the emergency vehicle priority system were excellent. Overall, it took 3 min 3 s to pass 1 km on an uncontrolled traffic signal section. On the other hand, it took 1 min 23 s to pass 1 km on the same section that was controlled. The shortening time to pass 1 km was 1 min 40 s, showing a 45.4% reduction. This means that the 15 min driving time can be reduced to 6 min and 49 s. From this result, an emergency vehicle priority system should be implemented nationwide as soon as possible.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.319-332
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• 2004

Due to their high strength to weight ratios and excellent durability, fiber reinforced polymer(FRP) is widely used in construction industries. In this paper, a shape optimum design of FRP bridge decks haying pultruded cellular cross-section is presented. In the problem formulation, an objective function is selected to minimize the volumes. The cross-sectional dimensions and material properties of the deck of FRP bridges are used as the design variables. On the other hand, deflection limits in the design code, material failure criteria, buckling load, minimum height, and stress are selected as the design constraints to enhance the structural performance of FRP decks. In order to efficiently treat the optimization process, the cross-sectional shape of bridge decks is assumed to be a tube shape. The optimization process utilizes an improved Genetic Algorithms incorporating indexing technique. For the structural analysis using a three-dimensional finite element, a commercial package(ABAQUS) is used. Using a computer program coded for this study, an example problem is solved and the results are presented with sensitivity analysis. The bridge consists of a deck width of 12.14m and is supported by five 40m long steel girders spaced at 2.5m. The bridge is designed to carry a standard DB-24 truck loading according to the Standard Specifications for Highway Bridges in Korea. Based on the optimum design, viable cross-sectional dimensions for FRP decks, suitable for pultrusion process are proposed.

• Journal of Korea Port Economic Association
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• v.24 no.3
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• pp.79-99
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• 2008

All the major ports around the world as well as those in Korea have been exploring their own strategies to survive rapidly changing marine transport environment worldwide. In particular, Busan New Port under development still fails to meet expected logistical traffic, although it operates 6 berths. That is why it is necessary to point out current challenges in logistical strategy of Busan New Port for fully dealing with logistical traffic. Therefore, this study can propose the following ways to facilitate logistical traffic of Busan New Port. First, it is necessary to apply equal tariff to incentives given to shipping agent under the associations between existing harbors and Busan New Port. Second, it is required to increase governmental subsidy for truck freight transport. Third, it is demanded to seek possible ways to transport export and import freight and thereby create independent logistical traffic. Fourth, it is necessary to contact shipping agents residing in new ports and establish a logistical program for shipping freights via Europe, Middle East and Russia as well as those by way of North America, Japan, Korea and China, ultimately making sustainable marketing strategy to create a series of continuous transshipment freight, not temporary one. Finally, it is advisable to operate networked logistical programs with small- or medium-sized overseas shipping agents in business association with large-scale overseas shipping agents.

• Journal of Korea Port Economic Association
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• v.33 no.4
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• pp.73-82
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• 2017

Korea is the fifth largest producer of automobiles in the world, and this industry accounts for the highest portion of the entire manufacturing industry. It is an especially important industry occupying second place in the top 10 export items in Korea. Korea exports about 3 million units of cars produced in the country and abroad, based on new cars and excluding second hand cars. Japan, along with Korea, represents a high portion of the global automobile industry, and it exports more than 4 million cars to the rest of the world. In particular, both Korea and Japan export automobile and used cars produced within the country, almost all of them by PCC(Pure Car Carrier) or PCTC(Pure Car Truck Carrier). Therefore, automobile export ports are located near automobile factories, and are being used in export to foreign countries. However, there are inefficient problems, such as poor port facilities, yard space shortage for loading and unloading operations and lack of proficiency of cargo handling companies. As a result, there are delays in cargo operations, or ships waiting have occurred. Therefore, the purpose of this study is to measure and compare the efficiency of automobile export ports in Korea and Japan. To measure the efficiency of automobile export port, we used CRS and VRS models from DEA. The input and output parameters were set as length of quay, yard area and throughput of cars, and DMUs are 25 ports for evaluating the efficiency. As a result of the efficiency measurements, two Korean ports (Gwangyang and Ulsan) and three Japanes ports (Kanda, Omaezaki, Kanmon-Shimonoseki) showed high efficiency in both models. These results can be used to establish strategies for enhancing efficiency and competitiveness of automobile export ports in Korea and Japan.

• Journal of Radiation Protection and Research
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• v.45 no.3
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• pp.117-129
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• 2020

Background: Radiation portal monitors (RPMs) involving plastic scintillators installed at the border inspection sites can detect illicit trafficking of radioactive sources in cargo containers within seconds. However, RPMs may generate false alarms because of the naturally occurring radioactive materials. To manage these false alarms, we previously suggested an energy-weighted algorithm that emphasizes the Compton-edge area as an outstanding peak. This study intends to evaluate the identification of radioactive sources using an improved energy-weighted algorithm. Materials and Methods: The algorithm was modified by increasing the energy weighting factor, and different peak combinations of the energy-weighted spectra were tested for source identification. A commercialized RPM system was used to measure the energy-weighted spectra. The RPM comprised two large plastic scintillators with dimensions of 174 × 29 × 7 ㎤ facing each other at a distance of 4.6 m. In addition, the in-house-fabricated signal processing boards were connected to collect the signal converted into a spectrum. Further, the spectra from eight radioactive sources, including special nuclear materials (SNMs), which were set in motion using a linear motion system (LMS) and a cargo truck, were estimated to identify the source identification rate. Results and Discussion: Each energy-weighted spectrum exhibited a specific peak location, although high statistical fluctuation errors could be observed in the spectrum with the increasing source speed. In particular, ¹³⁷Cs and ⁶⁰Co in motion were identified completely (100%) at speeds of 5 and 10 km/hr. Further, SNMs, which trigger the RPM alarm, were identified approximately 80% of the time at both the aforementioned speeds. Conclusion: Using the modified energy-weighted algorithm, several characteristics of the energy weighted spectra could be observed when the used sources were in motion and when the geometric efficiency was low. In particular, the discrimination between ⁶⁰Co and ⁴⁰K, which triggers false alarms at the primary inspection sites, can be improved using the proposed algorithm.

• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.652-660
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• 2007

The study was intended to investigate the changes of construction types of 216 non-national forest roads, which were completed between 1989 and 2005 in Jeollabuk-do, by analyzing their drawing and specification. It was found that the mean length of yearly construction has been significantly reduced after the Policy of Green Forest Roads compared with before the policy. Soil cut-off of earth work was changed from bulldozer to a combination of bulldozer and excavator. Soils were transported by truck in all design, but establishment of spoil-bank was not designed at all. The design of slope revegetation works was developed from turfing and Bastard indigo planting to seed spray, combination of seed spray and belt-sodding, and mulching with coir net and rice straw. In design of the culvert, the average interval of culvert installation was reduced to 92m in step 3, the dimension of culverts was expanded to over 600 mm after step 2, and all drainpipes were corrugated steel pipes. The design length of concrete pavement increased from 40 m/km of step 1 to 240 m/km of step 3. Thanks to the enormously increased amount of concrete pavement, the stability and functionality of forest roads could be improved. Stone masonry was the main work drawn for slope stability, and concrete retaining wall and gabion have been drawn for same object since 1999.

• Journal of Distribution Science
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• v.13 no.10
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• pp.123-133
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• 2015

Purpose - The Korean government has devised intermodal transportation policies and granted subsidies to shippers and logistics companies that made a conversion of transportation means through the policies. This provides support by expanding the complex uniform railroad transportation and overhauling the deteriorated railroad facilities. As for 2013, however, the freight transportation percentage of railroad was 4.5% in tons and 8.5% in ton kilometers. Meanwhile, since the 1990s, developed countries such as the U.S. and Europe have been trying to expand intermodal freight transport with a legal and institutional support to build a logistics system corresponding with social and economic environmental changes. In this study, I set out to examine the effects of the intermodal freight transport policies in the EU and the U.S., and to explore the direction of setting up a rail intermodal transport system in South Korea. Research design, data, and methodology - The paper used a qualitative research methodology through the literature review. First, was an overview of Intermodal transportation in the EU, U.S. and UN. Second, it describes the development of transport in Europe and the U.S. with particular emphasis on intermodal freight transport. Third, it explores the direction of setting up a intermodal freight transport in South Korea. The last section contains concluding remarks. Results - As for the EU, it has been promoting integration between transport and intermodal logistics network designs while utilizing ITS or ICT and supports for rail freight intermodal by giving reduction to a facilities fee or subsidizing for rail freight in order to minimize the cost of external due to freight transport. On the other hand, as for the U.S., it has been made up of an industrial-led operating project and has been promoting it to improve accessibility between intermodal hubs and cargo terminals through intermodal corridor program, and an intermodal cargo hub access corridor projects, etc. Moreover, it has tried to construct intermodal transport system using ITS or ICT and to remove Barrier. As a result, in these countries, the proportion of intermodal freight transport is going to be the second significant transport compared with rail and maritime transport. An Effective rail intermodal transport system is needed in South Korea, as seen in the case of these countries. In order to achieve this object, the following points are required to establish radical infrastructure policy; diversify investment financing measures taken under public-private partnerships, legal responsibilities, improvement of utilization of existing facilities to connect the railway terminal and truck terminal, and enhancement service competitiveness through providing cargo tracking and security information that combines the ITS and ICT. Conclusions - This study will be used as a basis for policy and support for intermodal freight transport in South Korea. In the future, it is also necessary to examine from the perspective of the shipper companies using the rail intermodal transport, ie, recognition of shipper, needed institutional supports, and transportation demand forecasting and cost-effective analysis of the railway infrastructure systems improvement.

• Korean Security Journal
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• no.54
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• pp.149-179
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• 2018

October 31, 2017, a man named Saipov who follows ISIS killed 8 people and injured nearly 20 others by driving his truck to the riverside bicycle path in Manhattan, New York, in an act of terror. June 5, 2017, the Islamic extremist Yacqub Khayre held a woman hostage in a suburb of Melbourne, Australia, before being killed by the police. Various countries around the world including the UK, France, and Germany are in war against terrorism. The terrorists change their target from hard targets such as government officials to vulnerable soft target, intensifying the public's fear, and, unlike in the past when they were organized by governments or organizations, extremists such as ISIS followers are now acting on their own in the act of terrorism. Also, as they use vehicles, pressure cooker, and other objects that can be easily found for terrorism, it is becoming more difficult for the police to prepare against terrorist attacks. Meanwhile, some terrorism researchers argue that conversational techniques (negotiation) used by the police are now of no use, as shown in the cases like 9/11 attacks in 2001 and 2016 Nice attack in France in which the suspects committed terrorist attacks without leaving enough time for the police to take action and that, therefore, tactical suppression techniques need to be developed. Therefore, this study suggested police negotiation techniques are necessary not only for terrorist attacks but also for overall police work, including handling intoxicated people at police station, and proposed ways to activate conversational techniques for police organizations.