• Composites Research
• /
• v.18 no.1
• /
• pp.45-54
• /
• 2005

The delamination in the filament-wound composite flywheel rotor often lowers the performance of the flywheel energy storage system. A conventional ring type hub usually causes tensile stresses on the inner surface of the composite rotor, resulting in lowering the maximum rotational speed of the rotor. In this work, the stress and strain distributions within a hybrid composite rotor were derived from the two-dimensional governing equation with the specified boundary conditions, and an optimum pressure at the inner surface of the rotor was proposed to minimize the strength ratio and maximize the storage energy. A split type hub was introduced to apply the calculated optimum pressure at the inner surface, and a spin test was performed up to 40,000 rpm to demonstrate the performance of the split type hub with radial and circumferential strains measured using a wireless telemetry system. From the analysis and the test, it was found that the split type hub successfully generates a compressive pressure on the inner surface of the rotor, which can enhance the performance of the composite rotor by lowering the strength ratio within the rotor.

• Journal of Korea Port Economic Association
• /
• v.25 no.1
• /
• pp.87-106
• /
• 2009

This paper is intended to suggest benchmarking ascension for the Gwangyang Port as a hub for international logistics. Most countries that seek to join. and lead, the global trading system as they work to develop production and logistics systems that establish a reputation for leadership in international logistics. Our focus in this research is on the Gwangyang Port and whether Gwangyang Port is capable of carving out a competitive niche as a hub of international logistics. Our analysis is based on comparison and analysis with benchmark port developments around the world. As proposals to promote and activate Gwangyang Port as a hub for international logistics, we recommended in this paper several benchmarks. First, Gwangyang Port FTZ must strengthen the incentive system for tenant companies and providing an inducement for new global companies. Second, Gwangyang Port needs to moderation of regulation on the investment tenant companies and strengthening one-stop service. Third, it is required to stabilize labor and management relationship and securing of flexibility of labor market. Lastly, Gwangyang Port must strengthen mutual interaction of Free Economic Zone (FEZ), Customs Free Zone(CFZ) and Free trade Zone(FTZ) in Korea.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.1
• /
• pp.33-39
• /
• 2017

This study identified a candidate area and route for construction of a hub & spork system for coastal passenger ships. For this purpose, the characteristics of the hierarchy structure of other transportation and the operating system of coastal passenger ships were analyzed. Evaluation factors for selecting alternative areas and routes for the construction project were then extracted. Secondly, the relative importance of these evaluation factors for alternative routes were calculated using the Analytic Hierarchy Process (AHP) method. Finally, the importance of these evaluation items and quality of the alternative areas and routes were considered to select a primary candidate area and route. Therefore, four evaluation items such as the number of passenger-ship routes, the number of passengers, the number of cars, and the number of residences were extracted, and the Mokpo area was selected as the target area. In addition, four evaluation items such as he number of islanders, the number of local governments, geographical conditions and passenger ship operators were extracted, and the Yeonggwang route was selected as priority candidates for this construction project. Meanwhile, for the expansive implementation, step-by-step promotion is needed along with the expansion of terminal facilities, the securing of large ships, and the introduction of a semi-public system for coastal passenger ships.

• Aerospace Engineering and Technology
• /
• v.3 no.2
• /
• pp.217-228
• /
• 2004

This paper presents the rotating test techniques and the results of the roating test of the small-scaled hingeless rotor system with composite paddle blades in hover and forward flight conditions. The small-scaled rotor system was designed using froude-scaled properties of full scale rotor system. Metal flexures and composite flexures were made as hub flexures by the same dynamic properties of rotor system. The rotating tests of hingeless rotor system installed in GSRTS at KARI were carried out to get lead-lag damping ratios and aerodynamic loads of the hingeless rotor system. MBA(Moving Block Analysis) technique was used for the estimation of lead-lag damping ratio. 6-components balance was installed between hub and main shaft and straingauges on blades were instrumented for the measurements of aerodynamic loads of rotor system. Tests were performed on the ground and in the wind tunnel according to the test conditions of hover and forward flight, respectively.

• Journal of Distribution Science
• /
• v.12 no.2
• /
• pp.95-103
• /
• 2014

Purpose - Korea has a better geographical location than other nations in the Northeast Asian region. This means that Korea has an opportunity to become the center of international physical distribution in Northeast Asia. Korea should take advantage of this opportunity by exploring appropriate strategies to achieve this goal, assuming government willingness, with a view to capitalizing on the geographical advantage of the Korean peninsula and constructing a comprehensive physical distribution network system. If we prepare for this scenario, Korea could become the center of international physical distribution in Northeast Asia. Research design, data, and methodology - This study has the purpose of determining how shipping companies form partnerships with third-party logistics providers, and the relevant implications. The survey methods used were personal interview and a questionnaire distributed through e-mail, fax, mail, and telephone. A total of 600 questionnaires were distributed, out of which 285 were returned. Of the collected questionnaires, 10 were excluded because of insufficient content, leaving 275 to be used in the study as available valid samples. The data that was collected from these samples was analyzed using the data coating process and by employing a statistical package program. Results - Flexible policies, administration, and systems will be needed to create better business practices. In this dissertation, first and foremost, the results reveal that in order to become the center of Northeast Asian logistics, Korea must transition into a new paradigm based on the current economic and social systems that have stemmed from bureaucracy, inflexibility, chauvinism, and egalitarianism. Flexible policies, administration, and systems will be required to create better business practices. Domestic logistics corporations need to occupy a strategic logistics hub, create a logistics network, and activate value-added logistics business strategies by ensuring significant manpower and by building a logistics information system to strengthen their competitive edge, creating an improved system. Conclusions - In this dissertation, first and foremost, we point out that in order to become a center of North East Logistics, Korea should change to a new paradigm from the old one based on current economic and social systems that have stemmed from bureaucracy, inflexibility, chauvinism, and egalitarianism. More reasonable business laws, systems, and policies based on market-driven flexibility and transparency should be created. Moreover, social norms and rules should be reasonably established, to accomplish political and social security. Korea has to cultivate a culture of tolerance for foreign companies. This involves a change of paradigm for the development of the capital city and satellite cities. It will take a powerful task force or organization to plan and execute the vision that aims to meet these needs, accomplish the necessary goals, use the appropriate system effectively, and make Korea a key country in the field of Northeast Asian logistics.

• Proceedings of the IEEK Conference
• /
• 2000.11a
• /
• pp.209-212
• /
• 2000

This paper discusses performance evaluation methodologies for wired/wireless Ethernet adaptors. This paper defines test cases for performance evaluation of LAN adaptor and its environments. Performance evaluation of LAN adaptor is mote complex as compared with interconnection devices such as Ethernet HUB and Ethernet switch, because its performance depends on the system on which the adaptor is plugged. Such dependencies include CUP type, RAM size, system bus architecture(PCI bus clock), etc.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2000.11a
• /
• pp.265-267
• /
• 2000

The objective of this study is to analyze, design and evaluate a new gas cleanup or sampling system that will remove erosive, corrosive, and fouling contaminants present in an effluent stream as either solid or liquid particles providing a clean gas stream. The gas clean-up or sampling system considered in this study is an irrigated, rotating element device. The device consists of a central disk-like hub from which emanate radially wires or cylindrical elements. (omitted)

• Proceedings of the KOR-KST Conference
• /
• 1998.09a
• /
• pp.59-64
• /
• 1998

The Railway Station for Passenger Transport is an important part of the railway transport business. It is also the main changing hub in the comprehensive traffic system in cities. This passage, taking Shanghai Railway Station as an example, deals with the modem management of the railway station for passenger transport and the double-ring quality system of the setting-up of the three flows(the passenger, the train and the luggage and the two operation procedures dispatch and arrival)

• Journal of the Institute of Convergence Signal Processing
• /
• v.6 no.2
• /
• pp.95-99
• /
• 2005

This paper presents an accurate recovery method of the reference clock which is needed for network synchronization in two-way satellite multimedia systems compliant with DVB-RCS specification and which use closed loop method for burst synchronization. In these systems, the remote station transmits TDMA burst via return link. For burst synchronization, it obtains reference clock from program clock reference (PCR) defined by MPEG-2 system specification. The PCR is generated periodically at the hub system by sampling system clock which runs at 27MHz $\pm$ 30ppm. Since the reference clock is recovered by means of digital PLL(DPLL) using imprecise PCR values due to variable random jitter, the recovered clock frequency of remote station doesn't exactly match reference clock of hub station. We propose a robust recovery method of reference clock against random delay jitter The simulation results show that the recovery error is remarkably decreased from 5 clocks to 1 clock of 27MHz relative to the general DPLL recovery method.

• Journal of the Society of Naval Architects of Korea
• /
• v.35 no.2
• /
• pp.51-62
• /
• 1998

In this paper, a CAD/CAM system for 5-axis machining of model propeller is introduced. This system has been developed under the environment of personal computer and Windows NT. In order to enhance the productivity, existing text-based design S/W was integrated into this graphic-based system. Non-Uniform Rational B-Spline method is used to represent the sculptured surface of propeller blades and hub using point data, and surface blending between blade and hub is realized in this system. For 5-axis machining of sculptured surface, tool/work collision and interference are checked and inverse kinematic analysis is performed to make NC data. In addition, tool and workpiece are animated on the PC monitor by preparing NC verification module. Finally, optimal cutting conditions are determined empirically and those cutting conditions are integrated into this S/W so that the whole process from design to machining can be done automatically.