• 대한안전경영과학회지
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• 제12권4호
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• pp.175-181
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• 2010

The government have plans to improve the railway transport capacity and transport hub for the sustainable national transport and logistics system. Specially, there are much efforts to improve transportation capacity such as high speed transportation of rail freight, enlargement of BT train, development of double stack train, etc. between railway transport hubs. If the transport capacity between railway logistics hubs is increased as planned, we must increase the handling capacity of railway hub terminals. But there are limits to enlarge the terminal infrastructure because of investment scale, location circumstances and urban development plans. To ensure the capacity, with the minimum required enlargement of infrastructure, it is necessary to extremely increase the efficiency of terminal operations. For improving the efficiency, we have to introduce the efficient terminal operation systems based on u-IT and operation optimize technologies. In this paper, we analyse the issues and problems of railway terminals(including ICD) and suggest the concept of intelligent railway terminal and the construction components of technology.

• 설비공학논문집
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• 제14권7호
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• pp.567-574
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• 2002

In the present study, ventilation flow rates and pressure rises through a road tunnel are simulated numerically using CFD with the various conditions such as roughness height, swirl angle of jet fan, entrance and exit effect and hub to tip ratio. By using a modified wall function, friction factor can be predicted under 10％ of error with respect to the Moody chart for the circular pipe flow and 15％, for the present tunnel. For more precise design, the effects of the swirl angle and hub to tip ratio of jet fan, which is not included in the theoretical equation of pressure rise by jet fan are necessary to be considered.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2000년도 가을 학술발표논문집 Vol.27 No.2 (3)
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• pp.449-451
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• 2000

본 논문에서는 분산 이기종 시스템들로 구성되는 다수의 독립된 인터넷 상점들과 이들을 연합하여 공동 포인트 적립, 공동 상품 검색 등의 통합된 서비스를 제공하는 인터넷 쇼핑몰 허브 싸이트에서 고객 개개인에게 맞춤 상품 정보 및 광고를 제공하기 위한 방법을 제시한다.

• 한국건축시공학회지
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• 제22권4호
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• pp.379-390
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• 2022

다양한 산업분야에서 4차 산업혁명 기술은 그 활용도가 날로 커지고 있다. 건설업계에서도 드론, IoT, 센서기술, 디지털트원 등의 도입을 통해 4차 산업혁명에 걸맞은 변화를 꾀하고 있으나, 그 변화는 타 산업에 비해 더디게 진행되고 있다. 그럼에도 불구하고 최근 불고 있는 건설업계의 디지털화와 디지털 전환은 건설산업이 처해 있는 고질적인 문제들을 개선하고 혁신하는 새로운 패러다임이 될 수 있다. 따라서 본 연구에서는 디지털화와 디지털 전환에 반드시 필요한 데이터 허브와 데이터 허브의 이용을 위한 API를 활용한 케이스 스터디를 진행해 보고, 이를 통해 데이터 허브와 API 활용에 대한 효율성과 타당성에 대해 고찰해 보았다. API 시스템 도입 시 일인 평균 약 23%의 예산 절감 효과가 있는 것으로 나타났으며, 약 4.4배의 비용대비 편익이 발생하는 것으로 나타나 사업 추진 타당성은 매우 높은 것으로 나타났다. 따라서, 본 연구의 결과 및 프레임 워크는 관련 연구의 기초 연구자료가 될 것이며, 관련 기술 도입을 촉진하기 위한 좋은 사례 연구가 될 것이다. 이는 궁극적으로는 건설업의 스마트화를 위한 디지털화와 디지털 전환에 기여 할 것이다.

• 항공우주기술
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• 제2권2호
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• pp.33-44
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• 2003

본 논문은 힌지없는 로터 시스템의 설계 핵심기술인 복합재료 플렉셔 설계 및 패틀형 복합재료 블레이드 설계/해석 기법을 소개하였다. 기존 금속재 혹은 엔지니어링 플라스틱 플렉셔 부품을 복합재료를 사용하여 설계한 후 NASTRAN과 FLIGHTLAB을 이용하여 구조 해석 및 동역학 특성 해석을 수행하였다. 패들형 블레이드를 복합재료 힌지없는 플렉셔 장착 허브에 연결한 힌지없는 로터 시스템에 대한 동적 특성을 살펴보았다. 또한 패들형 블레이드를 기존 실물크기 블레이드 구조 자료를 이용하여 프루드 축소화하였으며 축소값을 이용하여 블레이드를 설계하였다. 이 과정을 통해 형상이 복잡한 패들형 복합재료 블레이드에 대한 형상 설계 및 단면구조 설계 기법을 익혔다. 본 논문은 현재 수행중인 “차세대 헬리콥터 로우터 시스템 개발” 사업 등에 직접 적용될 수 있을 것으로 기대된다.

• Smart Structures and Systems
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• 제7권2호
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• pp.103-116
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• 2011

This paper is concerned with the trajectory tracking and vibration suppression of a single-link flexible arm by using piezoelectric materials. The dynamics of a single flexible arm with PZT patches as sensor and actuator is derived using extended Hamilton's principle. Resulting equations show that the coupled beam dynamics including beam vibration and its rigid in-plane rotation takes place in two different time scales. By using singular perturbation theory, the system dynamics is divided into two subsystems. Then, a composite control scheme is elaborated that makes the orientation of the arm track a desired trajectory while suppressing its vibration. The proposed controller has two parts: one is a tracking controller designed for the slow (rigid) subsystem, and the other one is a stabilizing controller for the fast (flexible) subsystem. The outputs considered for the system are angular position of the hub and voltage of the sensor mounted on the structure. To avoid requiring further measurements of beam vibration and also angular velocity of the hub for the fast and slow control laws, respectively, two sliding mode observers for estimating the unknown states are also designed.

• Tribology and Lubricants
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• 제29권6호
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• pp.397-402
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• 2013

This study examined the tribological characteristics of the drive shaft and axle system in vehicles. The first drive shaft example contained end play for a CV joint that transferred part of the transmission power to the wheel. The joint part of the drive shaft was deformed because of reduced durability due to wear. Thus, vibrations caused the body to shake and become unbalanced when the drive shaft transferred the power. The second example was the cross-section of a shaft that connected the slip-connection of the propeller shaft on the input side to the yoke flange of the output side; the durability was reduced because of corrosion. End play caused by wear between the bearing and cross-section shaft appeared to cause shaking. In the third example, a grease leak reduced lubrication and thus caused damage to the hub bearing and inside the knuckle. The failure was produced by sticking. The fourth example had noise produced by the gear and gear transfer. This was due to the backlash of the pinion and few ring gears for the differential gear. Therefore, drive shaft and axle systems must be thoroughly checked and managed to minimize and reduce failure phenomena.

• 한국유체기계학회 논문집
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• 제12권5호
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• pp.47-53
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• 2009

A rotordynamic and detailed stability analysis in accordance with API 617 standard were performed with a turbo-compressor, which is one of key rotating machinery in refinery, petroleum, and power plants. The system is composed of rotor shaft, impeller, sleeve hub, balance drum, and coupling hub. The rotor system is supported by tilting pad bearings, which has 5 pads and pad on loading condition. The rotordynamic analysis specified by API 617 includes the critical speed map, mode shape analysis, Campbell diagram, unbalance response analysis, and stability analysis. In particular, the specifications of stability analysis consist of a Level 1 analysis that approximates the destabilizing effects of the labyrinth seals and aerodynamic excitations, and Level 2 analysis that includes a detailed labyrinth seal aerodynamic analysis. The results of a rotordynamic analysis and stability analysis can evaluate the operating compressor health and can be utilized as a guide of its maintenance, repair and trouble solution.

• 유통과학연구
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• 제21권4호
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• pp.69-80
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• 2023

Purpose: In the landscape of global challenges, the adoption of new technologies and the implementation of intellectual capital are seen as the main vehicles to enhance banking operations. Inspired by this issue, our study is to discover the effect of technological investments and intellectual capital on one of the most important dimensions of banking operations, namely deposit intermediation. Research design, data and methodology: To tackle this concern, we utilize the data of 12 banks from 2011 to 2020 in Vietnam, and perform the multivariate regression analysis as well as provide different robustness tests. Results: Our empirical analysis demonstrates that a surge in technological expenditures would foster distribution of deposit intermediation of banks. Also, the blend of technology spending and intellectual capital plays a key role in boosting this function of banks. Conclusions: The study would bring one of new evidence for bank managers and national authorities in Vietnam, where has undergone the completely reform period in banking system. Accordingly, technological innovation and intellectual capital should be taken into consideration when managers and regulators build business strategies and related policies. The findings are also useful for nations bearing a close resemblance to Vietnamese financial system.

• Journal of Power Electronics
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• 제18권1호
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• pp.225-233
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• 2018

This paper proposes a universal system control strategy for voltage source converter (VSC) based high voltage direct current (HVDC) systems. The framework of the designed control strategy consists of five layer structures considering the topology and control characteristics of the VSC-HVDC system. The control commands sent from the topmost layer can be transmitted to the next layer based on the existing communication system. When the commands are sent to each substation, the following transmission of commands between the four lower layers are realized using the internal communication system while ignoring the communication delay. This hierarchical control strategy can be easily applied to any VSC-HVDC system with any topology. Furthermore, an integrated controller for each converter is designed and implemented considering all of the possible operating states. The modular-designed integrated controller makes it quite easy to extend its operating states if necessary, and it is available for any kind of VSC. A detailed model of a VSC-HVDC system containing a DC hub is built in the PSCAD/EMTDC environment. Simulation results based on three operating conditions (the start-up process, the voltage margin control method and the master-slave control method) demonstrate the flexibility and validity of the proposed control strategy.