• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.1
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• pp.47-52
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• 2010

The wave energy absorption efficiency and the first-order and the time-mean second-order wave loads of a three-dimensional bottom-mounted oscillating water column (OWC) chamber structure are studied. The potential problem is solved by making use of a hybrid Green integral equation associated with the finite-waterdepth free-surface Green function outside a twin chamber and the Rankine Green function inside taking account of the fluctuating air pressure inside the chamber. Numerical results of the primary wave energy converting efficiency and the oscillating and steady wave loads of a three-dimensional bottom-mounted OWC pilot plant have been presented.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.372-384
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• 2022

Total shipping accounts for 2.9 % of the annual average percentage of global anthropogenic GHG emissions. The International Maritime Organization implements EEDI (Energy Efficiency Design Index), Energy Efficiency eXisting-ship Index (EEXI), and Carbon Intensity Indicator (CII) as regulatory frameworks for shipping decarbonization. The Republic of Korea has enforced the Act on Development and Popularization of Greenship from 2020 and publicly announced the 1st national plan which was named 『2030 Greenship-K Promotion Strategy』 for the activation of a greenship market. The Greenship Certification Scheme is going on for the sustainability of Korean shipbuilding and shipping industries, to secure clean maritime environments, as well as to contribute to the national economy. Greenship Certification guarantees the credit of such eco-friendly technologies and products for shipping. The certification is going to be the basis of industrial competitiveness in coastal and international shipping. This study investigates an existing certification process, identifies the limitations, and proposes the process improved with several case studies. The improved certification scheme may have rationality for Net-zero with regard to climate alignment.

• Membrane and Water Treatment
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• v.15 no.1
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• pp.1-9
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• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.97-105
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• 2009

It is expected that logistics standardization have an great effect on industry and national economy due to cost saving and improving efficiency. Therefore all countries of the world make a strenuous effort to take a lead of logistics standardization Despite such efforts of every country, our country remained a lukewarm attitude about logistics standardization. Especially, our country remained a lukewarm attitude about logistics standardization effect quantify. We have to suggest the necessity of standardization and the effect for carrying out logistics standard. So, this study performed literature review and case study for development of effect valuation method. Also, this study developed effect valuation standard for quantifiable standardization effect and drew the effect valuation standard model. First, the measure of preliminary effectiveness was chosen for MOE selection. As a results, vehicle load ratio, delivery cost, keeping space efficiency warehouse automation ratio, etc. were selected. Then, vehicle/truck load ratio, warehouse keeping efficiency, up unloading hour, packaging cost, consistency transportation ratio were chosen for MOE of pallet standardization.

• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.47-56
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• 2013

The present study proposed a methodology to analyze the networking efficiency of arterial road networks. The methodology was motivated to design three-dimensional networks and to analyze the networking ability quantitatively, which is a novel approach compared to existing methods depending on the two-dimensional network definition and the qualitative analysis for improving arterial road networks. The method considered the interdependence between high-level freeways and low-level highways, the ITS-based information for traffic and road conditions, and the physical networking. These three factors were quantified by a networking index (NI), and the networking efficiency was measured by a networking rate (NR). The present study proved that the networking efficiency (NR) was influenced by travel information sharing (i.e., ITS) and physical factors. This supports the fact that the integrated improvements of physical and ITS factors are necessary for an arterial road. The proposed method was applied for an actual arterial road network. It was found that the nation-wide NR was higher than that for the metropolitan area, which might be due to the difficulty in switching between high- and low-level networks and the lack of ITS functions in the metropolitan area.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.2
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• pp.77-82
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• 2022

Recently, research on the development of low-cost/high-efficiency water electrolysis catalysts to replace noble metal catalysts is being actively conducted. Since overvoltage reduces the overall efficiency of the water splitting device, lowering the overvoltage of the oxygen evolution reaction (OER) is the most important task in order to generate hydrogen more efficiently. Currently, noble metal catalysts show excellent characteristics in OER performance, but they are experiencing great difficulties in commercialization due to their high price and efficiency limitations due to low reactivity. In this study, a water electrolysis catalyst Ni-MWCNT was prepared by successfully doping Ni into the MWCNTs structure through the pulsed laser ablation in liquid (PLAL) process. High resolution-transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) were performed for the structure and chemical composition of the synthesized Ni-MWCNT. Catalytic oxygen evolution reaction evaluation was performed by linear sweep voltammetry (LSV) overvoltage characteristics, Tafel slope, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Chronoamperometry (CA) was used for measurement.

• Journal of Internet Computing and Services
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• v.21 no.4
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• pp.109-116
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• 2020

With the advent of high-speed railways, railways are one of the most frequently used means of transportation at home and abroad. In addition, in terms of environment, carbon dioxide emissions are lower and energy efficiency is higher than other transportation. As the interest in railways increases, the issue related to railway safety is one of the important concerns. Among them, visual abnormalities occur when various obstacles such as animals and people suddenly appear in front of the railroad. To prevent these accidents, detecting rail tracks is one of the areas that must basically be detected. Images can be collected through cameras installed on railways, and the method of detecting railway rails has a traditional method and a method using deep learning algorithm. The traditional method is difficult to detect accurately due to the various noise around the rail, and using the deep learning algorithm, it can detect accurately, and it combines the two algorithms to detect the exact rail. The proposed algorithm determines the accuracy of railway rail detection based on the data collected.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.37-46
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• 2021

Government agencies, such as police and local governments, strive to prevent traffic hazards and create a comfortable road environment by pormoting transportation and road facilities. To this end, roads and transportation facilities are enhanced and adjusted, and improvement projects in areas with frequent traffic accidents are carried out. Usually, improvement projects in areas with frequent traffic accidents vary by projects and region. Moreover, these projects are carried out under the supervision of a person in charge and related parties. Hence, civil complaints and subjectivity are reflected in deriving priorities for the improvement projects, limiting the efficiency of the project. To this end, a study was conducted to estimate the direction of improvement of the project target site. This study comprehensively considered road, traffic, and accident conditions of representative projects with high effectiveness in handling traffic accidents. The results of the study state that the accuracy of estimating the improvement project was around 88%. In addition, the study found that there was a strong relationship between traffic volume, accident rate, and accident severity in estimating the improvement direction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.539-547
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• 2012

Increasing the mode transfer volume between public transportation modes has known to be necessary for efficiency improvement of public transportation system operation and it is also found to be important to have relevant transfer point selection with reflection of current travel pattern. This study is in regards to providing a selection guideline for the location of transfer point between public transport modes. This case study has been carried out for Daegu Metropolitan City especially for public transportation users behaviour by analysis of daily usage of transportation card to identify the transfer travel pattern. A cluster analysis was applied to categorize the pattern of transfer stop which induces many users and a discriminant analysis also utilized for grouping the stops by number of transfer trip. This research produces the estimation result of transfer volume for urban railway system no.3 in Daegu City which is currently under construction. In addition, the locations of transfer center has also been proposed.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.1 no.2
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• pp.225-253
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• 2006

Last 1970's Korea opened the Kyoung-bu highways from Seoul to Pusan, and Korea government had change the transportation policy to focusing on the road and motors. but 1990's Korea had been the heavily traffic jam in long distant transportation system and logistics. That's why Korea government studied on feasibility survey of High-speed train. As the KTX opens, traffic networks covering large areas In Kyeongbu-line (Seoul- Daejeon- Busan) are expected to raise synergy effects in economics as well as in korean culture respects. Having been playing an important transportation role in Korea for the last 106 years. With opening of the high speed railway, KORAIL in inevitable to make a drastic reform. To achieve this purpose, it is necessary that KORAIL has to be small and effective streamlined organization. In should increase traffic capacity by improving infra facilities. It need to also expand its internal functions by connecting the KTX with the conventional railroad system.