• Journal of the Korean Electrochemical Society
• /
• v.23 no.4
• /
• pp.90-96
• /
• 2020

Polymer electrolyte membrane fuel cells, which convert the chemical reaction energy of hydrogen into electric power directly, are a type of eco-friendly power for future vehicles. Due to the sluggish oxygen reduction reaction and costly Pt catalyst in the cathode, the research related to the replacement of Pt-based catalysts has been vitally carried out. In this case, however, the performance is significantly different from each other and a variety of factors have existed. In this review paper, we rearrange and summarize relevant papers published within 5 years approximately. The selection of precursors, synthesis method, and co-catalyst are represented as a core factor, while the necessity of research for the further enhancement of activity may be raised. It can be anticipated to contribute to the replacement of precious metal catalysts in the various fields of study. The final objective of the future research is depicted in detail.

• Bulletin of the Society of Naval Architects of Korea
• /
• v.32 no.4
• /
• pp.57-63
• /
• 1995

극지개발을 위해서는 극지의 혹독한 자연환경을 대상으로 하는 과학지식과 극지에서 사용되는 특수시설과 장비를 설계, 시공 그리고 운용하는 공학기술이 요구된다. 극지관련 공학기술은 저 온용재료 관련기술, 도로나 교량, 건축물과 같은 극한지 천연자원의 시추와 생산, 수송을 위한 해양구조물과 파이프라인 관련기술, 그리고 얼음의 재료특성에 관한 이론 및 실험으로 크게 구 분할 수 있다. (Table 1). 극지용 구조물과 빙해항행선박 (쇄빙선) 은 일반 해역에서 운용되는 구조물에 비해 형상, 구조강도, 의장, 저온특수설비 등에서 새로운 개념의 기술이 요구되기 때 문에 금후 국내 조선해양산업계가 지향해야 할 고도의 기술집약형 건조물이다. 또한 최근 들어 국내에서도 시베리아 천연자원의 해상운송을 위해 빙해역을 운항할 수 있는 유조선이나 일반 화물선을 확보해야할 필요성이 대두되고 있으며, 또한 국내 조선업계의 생산기술이 비약적으로 발전함에 따라 외국으로부터의 빙해항행선박의 수주도 이루어지고 있으나 아직 이들 선박의 설계를 위한 독자적인 기술은 미흡한 현실이다. 극지개발은 이론적 접근과 함께 실험에 의한 신뢰성 있는 자료를 축적해야 한다. 이를 위해서는 빙해수조(,ice model basin)의 건조나 빙역학 실험을 위한 냉동실험실 (cold room)의 건립을 위한 초기투자가 절실히 요구되며 산업계의 수 요에 따른 포괄적인 산학협동연구가 진행되어야 할 필요가 있다. 빙해수조와 냉동실험실은 빙 해역에 직접 접하지 않은 국가에서 극지공학 연구에 참여하기 위한 필수적인 시설인데 table 2에 대표적인 빙해수조의 설치장소와 규모에 대하여 정리하였다. 이 글은 우리 나라가 쉽게 접할 수 없는 극지환경을 이해하고 가까운 장래에 예상되는 수주경쟁에 대비하여, 국내외의 극지개발 동향을 분석하고 이에 대한 국내의 극지관련 연구의 현황과 앞으로의 전망을 살펴보기 위하여 준비된 것이다. 이 글에서는 극지공학 일반보다는 조선해양분야에 관련된 내용만으로 국한한다.

• Journal of Satellite, Information and Communications
• /
• v.7 no.1
• /
• pp.13-20
• /
• 2012

Despite of growing concern for developing meteorological satellites, poor investment has been realized to acquire effective and efficient satellite image processing technologies. In this study, not only qualitative exploration on mapping each elementary technology into related industries but quantitative inter-industry analysis induced from Total Cost of Ownership (TCO) of the Korean satellite image processing system were performed. Furthermore, economic assessment has been made by estimating internal rate of return(IRR) for the benefits returned versus TCO of the system. The results showed that agriculture and fisheries industry, tourist and leisure industry, and transportation industry were highly related with the acquisition of the system, and that 9.1 billion won of production-induced effects, 3.3 billion won of value-added-induced effects, and 54 individuals of employment-induced effects were anticipated except for those of directly relevant industries. Even in the pessimistic scenario, 7% of IRR exceeding 5.5% assumed as current public rate was postulated, consequently, the investment was fairly justified.

• The Journal of the Korea Contents Association
• /
• v.9 no.6
• /
• pp.357-369
• /
• 2009

With the development and generalization of internet and information technology, airlines has tried to reduce their business expenses and commissions to travel agencies and enhance service qualities through service automation and simplification, such as internet booking and ticketing, self check-in, in-flight internet and RFID for checked baggage. The statistical techniques conducted for this empirical analysis are frequency analysis, reliability analysis, factor analysis, confirmatory factor analysis and multiple regression analysis. This research has tried to examine factors of airline e-services that influence on recommendation re-purchase intention and satisfaction. Results has found that only on-line reservation and ticketing factor had significant effect for recommendation and re-purchase intention and all e-service factors produced significant effect to total satisfaction. It was also recommend that airlines have to provide easy and more familiar e-service system to their passengers to deliver better services.

• Journal of Korea Port Economic Association
• /
• v.25 no.3
• /
• pp.117-138
• /
• 2009

Heavy truck traffic causes serious damage to not only environment condition due to the emissions but also pavement condition. In Incheon city area, the highways of the port hinterland suffer from similar problems. Therefore, it is required to develop a policy to solve those problems, which should be under the collective agreement of the truck drivers, local residents, and policy makers. This paper compared the truck traffic volumes and re-pavement construction history for last 4 years and showed the real effect of the heavy truck traffic on the pavement. Furthermore, this study examined the pros and cons of the exclusive truck lane and truck only highway policies and conducted a survey of truck drivers, local residents, and policy makers. Each group showed different preferences for the policies particularly for the question asking the best implementable policy.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.4
• /
• pp.300-308
• /
• 2019

For drones to be used for industrial or agricultural applications, it is necessary to increase the payload and endurance. Currently, the payload and endurance are limited by the battery technology for electric powered drones. In addition, charging or replacing the batteries may not be a practical solution at the field that requires near continuous operation. In this paper, a procedure to optimize the power system of an electric hybrid drone that consists of an internal combustion engine, a generator, a battery, and electric motors is presented. The example drone for crop dusting is sized for easy transportation with a maximum takeoff weight of 200 kg. The two main rotors that are mechanically connected to the internal combustion engine provides most of the lift. The drone is controled by four electric motors that are driven by the generator. By analyzing the flow of the energy, a methodology to select the optimum propeller and motor among the commercially available models is described. Then, a procedure of finding the optimum operational condition along with the proper gear reduction ratios for the internal combustion engine based on the test data is presented.

• Journal of the Korean Institute of Gas
• /
• v.26 no.1
• /
• pp.7-19
• /
• 2022

Hydrogen purification is generally performed through chemical and physical methods. Among various types of purification method PSA(Pressure Swing Adsorption) is widely used with its purification capacity and economic efficiency. In Korea, most of the hydrogen used in automobiles and power generation fuel cells is purified using PSA. Hydrogen produced in petrochemical complexes has difficulties in transportation. The government is planning to install hydrogen extractors that produce hydrogen directly from consumers in connection with the city gas supply chain, and companies are also installing related research and demonstration facilities one after another. Europe and others have recently established safety standards related to PSA and are making efforts for systematic safety management at the construction and operation stage, but domestic safety standards related to PSA are still insufficient. This study aims to identify problems of existing facilities through surveys and risk assessment by companies operating existing PSA, and to prepare domestic technical standards including them in overseas technical standards to promote the safety of new and existing PSA systems.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.225-225
• /
• 2020

최근 국내·외에서는 재래식 소류사량 채집기를 이용한 직접계측방법의 한계를 보완하기 위해 음향센서(하이드로폰)를 활용하여 소류사가 이동할 때 발생하는 충돌음 신호로부터 소류사량을 간접적으로 추정하는 방법이 개발 검토되고 있다. 이러한 방법은 하이드로폰에 계측된 음향신호의 특성 중 음향 펄스 수와 소류사량의 상관성을 해명하는 연구가 주를 이루고 있다. 그러나 기존의 펄스 카운트 알고리즘은 원시신호에 대한 불충분한 노이즈 필터링 작업과 음향특성 중 진폭만을 고려하여 임계치를 설정하였기 때문에 운송되는 소류사량이 많을 경우 신호 파형의 중첩으로 인한 펄스 수의 과소평가, 감지 가능한 상한 입자 크기가 제한되는 등의 결점을 가지고 있다. 또한 대다수의 연구가 소류사량의 총량과 시계열적인 변화를 추정하는데 주안점을 두고 있어 소류사량의 입도분포를 추정하기 위한 연구사례는 매우 부족한 실정에 있다. 따라서 본 연구에서는 위와 같은 한계를 극복하기 위해 다양한 입경과 유속 조건을 고려한 단독입자 공급 실험을 통해 하이드로폰에서 계측되는 소류사 입경별 충돌음의 진폭과 특정 주파수대역을 기준으로 음향특성치를 효과적으로 필터링 할 수 있는 개선된 Band-Passs Method 방법을 제안하였다. 제안된 방법의 검증을 위해 기존의 음향신호 필터링 방법(증폭 채널 방법, 임계치 설정 방법)과 비교·분석을 수행한 결과 제안한 방법이 기존의 필터링 방법보다 높은 소류사량 추정률을 보이는 것으로 나타났다. 아울러 단일입경 연속공급 실험을 수행하여 입경별 소류사량 추정관계식을 산출하고 혼합입경의 입도분포 추정 가능성을 확인하였다. 연구수행의 최종단계로 혼합입경 소류사량 추정이 가능한 입경별 통합 소류사량 추정 알고리즘을 개발하고 실측 소류사량과의 비교·분석을 통해 알고리즘의 소류사량 추정 정밀도를 검증하였다.

• Korea Trade Review
• /
• v.46 no.3
• /
• pp.135-149
• /
• 2021

This study analyzes the economic effect through the use of the RCEP direct transport rules, and suggests the necessacity of logistics efficiency and policy alternatives. The advantage of the hub network has been widely applied to the international logistics system, but there is a limit in the FTA logistics system in which goods must be directly transported between two contracting parties. Therefore, based on the new RCEP direct transport rules and the theoretical review on the possibility of an FTA logistics hub, FTA logistics efficiency improvement is estimated. This study quantitatively estimated the economic effect of direct transportation, unlike the previous studies, which were limited to the analysis of judicial precedents or surveys. GTAP model was used through five scenarios according to the impact of the RCEP tariff cut and the FTA logistics hub establishment in Singapore or Korea. As a result of the analysis, Korea's trade volume increased by 0.38% of exports and 1.63% of imports, and RCEP would increase exports by 0.27% and imports by 0.42%. In particular, the establishment of an FTA logistics hub (0.71%) was found to have a greater effect on the improvement of terms of trade than a tariff cut (0.12%), confirming the necessity of establishing an FTA logistics hub in RCEP. As a policy proposal, the institutional support of the customs authorities for the use of RCEP, the expansion of the free trade area where BWT traded cargo can be stored, and the establishment of a system for issuing back-to-back certificates of origin with approved exporters.

• Journal of Navigation and Port Research
• /
• v.47 no.6
• /
• pp.419-429
• /
• 2023

The pinnacle of rapidly changing and advancing maritime transportation technology is expected to be the Maritime Autonomous Surface Ship (MASS). The implementation of various services within the MASS is likely to be feasible through the ship-centric network known as the S2X communication system. However, existing communication systems face issues such as service traffic saturation and failure to meet demanded functionalities, necessitating the proactive introduction of additional communication technologies. In this study, the concept of S2X communication for the MASS was redefined, deriving required functionalities and ultimately selecting frequencies suitable for utilization. Candidate frequency groups suitable for the derived communication requirements were identified, and communication frequencies prioritized for the initial application were chosen through expert consensus. It is anticipated that through further research, including experimentation to validate these frequencies, they could be utilized in implementing services for autonomous ship navigation in the future.