• Title/Summary/Keyword: 운송효율

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A DEA and Malmquist Index Approach to Measuring Productivity and Efficiency of Korean's Shipping Firms (DEA와 Malmquist 지수를 활용한 외항해운기업의 효율성 및 생산성 분석)

  • Hwang, Kyung-Yun;Sung, Bong-Suk;Song, Woo-Yong
    • International Commerce and Information Review
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    • v.14 no.3
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    • pp.323-350
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    • 2012
  • This study analyzes the efficiency of 25 shipping companies in Korea over the period 2005-2009, using Data Envelopment Analysis (DEA). Among 31 companies that listed in order of decreasing sales volume for the period 2006-2010, the sample companies has been selected on the ground of data availability. This study computes the companies' efficiency, estimates their year-on-year Malmquist productivity index, and analyzes the cause leads to the changes in the productivity, In particular, this study attempts, by dividing the companies into two group, listed or not, to compare the changes in the productivity and analyze the reasons. The results from static analysis based on CCR and BCC model indicate that listed companies are higher efficient than unquoted companies. The results from tests on the productivity changes based on the Malmquist productivity index show that 19 unquoted companies increase their average productivity by 16.2 percent year after year during the period but 6 listed companies increase by 0.5% during the same period.

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Exergetic Analysis of Ammonia-fueled Solid Oxide Fuel Cell Systems for Power Generation (암모니아 활용 고체산화물 연료전지 발전시스템의 엑서지 분석)

  • Thai-Quyen Quach;Young Gyun Bae;Kook Young Ahn;Sun Youp Lee;Young Sang Kim
    • Journal of the Korean Institute of Gas
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    • v.27 no.3
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    • pp.27-34
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    • 2023
  • Using ammonia as fuel for solid oxide fuel (SOFC) cells has become an attractive topic nowadays due to its high efficiency, environmental friendliness, and ease of storage and transportation. Several configurations of ammonia-fed SOFC systems have been proposed and investigated, demonstrating high electrical efficiency. However, to further enhance efficiency, it is crucial to understand the inefficient components of the system. The exergy concept is well-suited for this purpose, making exergetic analysis essential for ammonia-fed SOFC systems. This study conducts an exergetic analysis for three selected systems: a simple fuel cell system (FC), an anode off-gas recirculation system (RC-FC), and a recirculation system with water removal (RC-WR-FC). The results reveal that the exergetic efficiencies of the FC, RC-FC, and RC-WR-FC are 48.7%, 51.6%, and 58.4%, respectively. In all three systems, the SOFC stack is the main source of exergy destruction. However, other components with relatively low exergetic efficiency, such as the burner, air heat exchanger, and cooler/condenser, offer greater opportunities for improvement.

A study on the characteristics of Goryeo dynasty cargo tag mokkans In comparison with mokkans of the Song and Yuan dynasty (고려시대 화물표 목간의 특징에 대한 고찰 - 중국 송·원대(宋·元代) 목간과의 비교를 중심으로 -)

  • LEE, Yeonjae
    • Korean Journal of Heritage: History & Science
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    • v.54 no.4
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    • pp.60-77
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    • 2021
  • From 2007 to 2011, four Goryeo Dynasty vessels, namely the Taean treasure ship, Taean Mado Shipwreck No.1, No.2, No.3 were discovered in Taean area, Chungcheongnam-do province. From the shipwrecks, 175 pieces of mokkan (wooden tablet) were excavated. These mokkans are the only case of Goryeo Dynasty and represent the unique usage of mokkan as cargo tags, after the paper replaced the wooden tablets as writing materials. The Taean mokkans provide details, such as the year, recipient, port of origin, types of the cargo, quantity and unit, the name of the responsible person for shipment. Thus, they enable us to speculate about the characteristics of the cargo. Furthermore, through studying the writing style, form, material and manufacturing method, researchers can extract which form and characteristics were favored at that time. The Taean mokkans have no preset style for writing. Therefore, they can be written selectively and freely. And since the mokkan were attached to cargos, mokkans with furrows on upper side were favored, and efficiency and simplification of the manufacturing process were priorities in making mokkans. The Taean mokkans can be compared to those from the Shinan ship and the Quanzhou ship because those are of the same era and use. On the writing styles and information, Chinese mokkans are focused on the cargo owners, while The Taean mokkan includes more detailed information, such as the recipients. In forms, Chinese mokkans have maximum thickness of 1.0 centimeter and have pointed edges in lower parts, while mokkans from Taean do not have fixed thickness or edges. Furthermore, Chinese mokkans and Korean mokkans have different styles from manufacturing methods and material selections. These differences between Chinese and Goryeo mokkan are related to the differences between littoral-transport Goryeo ships and ocean-transport Chinese ships, such as shipping distances, types of cargo, shipping systems, packing methods, and transport operators. At the moment, because there are only small amount of data and materials of Chinese mokkan, comparative studies regarding Goryeo and Chinese mokkan can only be fragmentary. However, this article can be a base from which to expand the scope of Goryeo mokkan studies.

Implementation of Delivery Information Security System using DRM (DRM을 활용한 택배정보보안시스템 구현 방안)

  • Park, Doo-Jin
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.05a
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    • pp.846-847
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    • 2012
  • The domestic courier market, large and small companies working in more than 100 leading logistics service market is fully open. Year since 2001 has increased by 10%. 1.3 billion per year in 2011 saying the shipping box, and the market size is about 3 trillion won. Courier in 2012 with the growth of online shopping is expected to develop the industry further. However, these courier industry in appearance, but the consumer's personal growth and exposure, exploiting the fears of crime is high. In this paper, using DRM (Digital Rights Management) delivery method to implement information security system is proposed.

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A Study on link between The Port and Rail Transport for Nature-Friendly -Primarily on the Busan Port- (항만과 철도운송의 친환경적 연계를 위한 연구 -부산항을 중심으로-)

  • Lee, Myeong-Hwa;Kim, Hwan-Seong;Park, Jin-Hui
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2010.04a
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    • pp.165-166
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    • 2010
  • Today, because the international community recognized happing of environmental crisis on the world the international environmental agreements and advanced country's environmental regulations are very tight. Especially, port cities are posed strong threats to the environment due to receiving high pollution from ships and cargo vehicle emissions. So many advanced country (ex. United States, Japan, EU) implement Natural-friendly Port Policy and Program. Environmental-Regulations become more stringent in the future, management of low carbon dioxide emissions brings the competitiveness.(중략)

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The Logistics System and Feature of the Jeju Island (제주도 물류현황과 특징)

  • Han, Yu-Nam;Kim, Tae-Won;Kwak, Kyu-Seok;Nam, Ki-Chan
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.29 no.1
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    • pp.3-9
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    • 2005
  • This paper is aimed to analysis the logistics system of the Jeju island. Jeju island has a special feature about logistics system different from inland. In recent gradually increase of the jeju freight volumes but it has some problems about the port facilities shortage. We try to find the problems of the jeju and propose that an improvement plan.

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The Effect of Probe Tool Speed on Weld Characteristics and Strength during Friction Stir Spot Welding of Mg-alloy Sheets (마그네슘 합금 판재의 마찰 교반 점용접 시 툴 속도가 접합특성 및 강도에 미치는 영향)

  • Jung, Yoon-Chul;Park, Sung-Su;Shin, Hyung-Seop;Choi, Kwang
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.64-64
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    • 2010
  • 최근 그린 친환경, 지구온난화방지와 환경 부하물질저감, 기기 고효율화, 연비향상 등의 관점에서 항공기, 자동차 등 운송기계와 휴대용 전자제품 등 경량화가 요구되는 분야에서 경량합금의 사용이 급증하고 있다. 특히, 경량합금 중 가장 가벼운 마그네슘 합금은 최근 주목을 받고 있는 금속재료이다. 그러나 마그네슘합금은 알루미늄합금과는 달리 상온 성형성 및 접합성이 양호하지 않은 관계로 판재를 이용한 구조부품의 제작을 위해서는 많은 연구가 필요하다. 이러한 관점에서 본 연구는 마그네슘합금 판재의 마찰 교반 점용접을 시도하였다. CNC 밀링머신을 사용하여 프로브의 회전 및 삽입 속도에 변화를 주어 접합 특성을 평가하였고, 각 변수의 영향을 조사하였다. 적외선 열화상기와 로드셀을 사용하여 마찰 교반 점용접 중에 발생하는 교반부 온도와 접합부에 가해지는 수직부가하중의 거동을 측정하였다. 마찰 교반 점용접 후, 시험편의 접합 상태와 접합부 단면 관찰을 통해 접합 상태를 조사하였다. 그리고 인장전단 실험을 실시하여 마찰 교반 점용접된 시혐편의 접합강도를 평가하였고, 파단된 시험편의 파면을 관찰하였다.

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Establishment of Standard Model for Training Flight Infrastructure (훈련용 비행인프라 표준 모델 구축)

  • Lim, Jae-Hwan;Kim, Young-Rok;Choi, Yun-Chul
    • Journal of Advanced Navigation Technology
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    • v.22 no.3
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    • pp.189-197
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    • 2018
  • In Korea, most of the land area is composed of mountainous areas, making it difficult to develop airports because there is not enough open space to operate airports or airfields. However, the current development of the air transportation industry and the rapid increase of aviation demand, the construction of the training airfield infrastructure should be more actively reviewed for safe and smooth flight training. In this study, we analyze the actual condition of operation of domestic training airfield and the case study of overseas training site in order to establish appropriate level standard model of training infrastructures. In addition, this study suggests implications for the appropriate scale and operational efficiency of the training flight infrastructure.

Characteristics of Syngas Refinery via Rice Husk Gasification in the Updraft Fixed-bed Gasification System (Updraft 고정층 가스화 시스템에서의 왕겨 가스화 합성가스 정제특성)

  • Yoon, Youngsik;Sung, Hojin;Park, Sunam;Gu, Jaehoi
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.171.2-171.2
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    • 2011
  • 지속가능한 발전과 저탄소 녹색성장의 개념이 대두되면서 우리나라를 비롯한 주요 선진국은 자국의 화석연료 의존도를 낮추고 대체에너지로 환경친화적이며, 청정에너지로 각광받는 신 재생에너지의 활용에 경제적, 정책적 지원을 아끼지 않고 있는 실정이다. 실제로 유럽에서는 바이오매스의 일종인 우드칩을 활용한 가정용 보일러가 보급되고 있으며, 동남아시아에서는 열대식물을 이용한 저온열분해를 활용하여 바이오디젤을 생산하고 있다. 우리나라의 경우 대부분의 바이오매스는 발생되는 임야에서 재이용되거나 경제성이 있을 경우에 운송되어 재활용되고 있으며, 임부목과 같은 일부 바이오매스는 수익성이 없어 발생현지에 방치되는 경우도 있다. 본 연구에서 주목한 왕겨의 경우 미곡종합처리장에서 대량으로 발생되지만 그 활용도에 있어서 축적된 바이오에너지에 비해 에너지회수율이 저조하다고 할 수 있다. 왕겨는 임야에서 발생되는 폐목재나 다른 바이오매스에 비해 함유되어 있는 수분이 적고(12%), 휘발분의 함량이 많으며(58%), 고정탄소(17%), 회분(13%)로 열분해/가스화에 적용가능하다. 본 실험에서 생산된 합성가스의 활용방법으로는 보일러를 이용한 스팀 및 전력생산, 가스엔진을 이용한 전력생산, 폐열회수 등이 있으며 생산된 합성가스를 활용하기 위해서는 오염물질의 정제특성에 대한 연구가 선행되어야 한다. 따라서 본 연구에서는 합성가스 내에 존재하는 분진, 타르, HCl, HCN, $NH_3$의 제거효율을 조사하였다.

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A Study for Application of Logistics Collaboration in the Railroad (철도에서의 물류공동화 적용 방안에 관한 연구)

  • Chung, Byung-Hyun
    • Journal of the Korean Society for Railway
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    • v.14 no.5
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    • pp.452-460
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    • 2011
  • The logistics collaboration is begun in the transport part and introducing it in all fields of the distribution including delivery and the storage in these days. The effectiveness by the logistics collaboration is proved in many forms and adopted in many parts positively. However, logistics collaboration are enforced around road transport now. In this paper, it is examined for logistics collaboration introduction plan in the railroad part which is outstanding in environmental. The logistics collaboration are examined for transport and storage in not only the Railway main line transport but also the railroad station.