• Journal of the Korean Operations Research and Management Science Society
• /
• v.41 no.1
• /
• pp.99-111
• /
• 2016

This paper presents a framework to analyze the change in the research and development (R&D) efficiency of government-funded research institutes (GRIs) in Korea. Cumulative data envelopment analysis/Malmquist index method is utilized to analyze the changes in R&D efficiency of GRIs. Data analysis of the R&D activities of 10 GRIs in Korea Research Council of Fundamental Science & Technology showed that the average R&D efficiency of the 10 GRIs improved from 2009 to 2013. However, the efficiency of a few GRIs decreased in terms of the catch-up index. The proposed framework can help management teams diagnose the current state of R&D activities and determine the efficacy of strategic actions by comparing efficiencies in the past.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.41 no.2
• /
• pp.67-80
• /
• 2016

Under a rapidly changing environment, firms have attempted to co-operate with organizations that possess high technologies to improve their technical capabilities. Most countries have worked towards developing a suitable strategy for international technology co-operation based on the diagnostic results of their technological capabilities and indices. These diagnostic results indicate the level and degree of international technology co-operation that have been developed in academia. However, identifying the overall conditions of international technology co-operation based on existing indices is a difficult task. Hence, to address this problem, indices that can measure diverse perspectives of core technology co-operation activities need to be developed. This research aims to develop a framework for identifying the current state of international technology co-operation in diverse perspectives at the national level. We develop indices based on relevant literature and formulate an analytical framework for international technology co-operation in diverse perspectives using DEA analysis. The results are expected to contribute to effective technology planning at the national level by diagnosing capabilities for international technology co-operation from diverse perspectives.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.38 no.3
• /
• pp.23-35
• /
• 2013

It is very important that the calculation of railroad track capacity in infrastructure investment analysis and train operation planning. The dwelling time is one of the factors that influence in railroad track capacity. Current research in dwelling time has been focusing on theoretical investigation, the state of the research in effective variable (dwelling time etc) is insufficient. In this paper, we clearly draw the concept of railroad track capacity and the estimate on modeling of relationship railway demand and dwelling time. Also, we compare and analyze the variation of railroad track capacity according to transit railway demand in Gyeongin Line (Guro~Inchon). This paper is expected to contribute for improving on the in-using equations and methods in train operation planning as well as for improving level of service on railway user.

• Nuclear Engineering and Technology
• /
• v.56 no.6
• /
• pp.2011-2018
• /
• 2024

Since RF breakdown is one of the primary limitations to improving the performances of RF accelerators, extensive efforts have been dedicated to locating the breakdowns. However, most existing methods rely on specialized techniques, resulting in high financial burdens. Although the method based on transient response of transmission line (TL) is suitable for facilities with sporadic recoverable breakdowns, practical operations are susceptible to notable errors. This study revisits the fundamental theories of lossless TL and investigates the wave process to understand the characteristics of the reversed pulse induced by the breakdowns. By utilizing steadystate response of the TL and employing phasor method, we derive analytical formulas to determine the exact location of breakdowns within the faulty cell for constant-gradient TW accelerator. Furthermore, the derived formulas demonstrate their independence from RF phase, thereby distinguishing them from traditional phasebased methods. Additionally, experimental validations are conducted at the HUST injector, and the results confirm the consistency of the analysis. Thus, the proposed method represents a promising improvement over the TL-based approaches and serves as a valuable complement to current techniques. Importantly, this method demonstrates particular advantages for constructed TW accelerators seeking to achieve a balance among high performance, low costs, and compact layouts.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.10 no.1
• /
• pp.37-47
• /
• 2018

Dynamic simulation is critical for electrical ship studies as it obtains the necessary information to capture and characterize system performance over the range of system operations and dynamic events such as disturbances or contingencies. However, modeling and simulation of the interactive electrical and mechanical dynamics involves setting up and solving system equations in time-domain that is typically time consuming and computationally expensive. Accurate assessment of system dynamic behaviors of interest without excessive computational overhead has become a serious concern and challenge for practical application of electrical ship design, analysis, optimization and control. This paper aims to develop a systematic approach to classify the sophisticated dynamic phenomenon encountered in electrical ship modeling and simulation practices based on the design intention and the time scale of interest. Then a novel, comprehensive, coherent, and end-to-end mathematical modeling and simulation approach has been developed for the latest Medium Voltage Direct Current (MVDC) Shipboard Power System (SPS) with the objective to effectively and efficiently capture the system behavior for ship-wide system-level studies. The accuracy and computation efficiency of the proposed approach has been evaluated and validated within the time frame of interest in the cast studies. The significance and the potential application of the proposed modeling and simulation approach are also discussed.

• Journal of Korean Port Research
• /
• v.14 no.1
• /
• pp.13-26
• /
• 2000

In this paper, we compare and analyze the current state of the productivity of the stevedoring work among several container terminals in 1999. Based on these results of analysis, we firstly classify several factors which impede the efficient operations of container terminal as follows ; late arrival of container beyond cargo closing time(CCT), change of port of destination, change of vessel, and return cargo. Such factors are major cause for the cargo rehandling on terminals, thus deteriorate the overall performance of transfer crane during the stevedoring work. In order to improve the productivity of container terminal, we suggest that it is necessary for establishing and operating the efficient logistics management system. Especially, we emphasize the importance of information exchange on the scheduled cargoes among the relevant parties such as shippers, shipping companies, and terminal operators, which is the most effective way to alleviate the cargo rehandling.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.242-243
• /
• 2010

This paper investigates a power supply of medium voltage with enhanced ignition characteristics for plasma torch. Series resonant half-bridge topology is presented to be a suitable ignition circuitry. The ignition circuitry is integrated into the main power conversion system of a multi-phase staggered three-level dc-dc converter with a diode front-end rectifier. The plasma torch rated for 3MW, 2kA and having the physical size of 1m long is selected to be a high enthalpy source in waste disposal system. The steady-state and transient operations of plasma torch are simulated. The parameters of Cassie-Mary arc model are calculated based on 3D magneto-hydrodynamic simulations. Circuit simulation waveform shows that the ripple of arc current can be maintained within ${\pm}10%$ of its rated value under the existence of load disturbance. This power conversion configuration provides high enough ignition voltage around 5KA during ignition phase and high arc stability under the existence of arc disturbance noise resulting in a high-performance plasma torch system.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.38 no.10
• /
• pp.832-839
• /
• 1989

New chopper circuits for decoupled operation of the dc series motor are presented. These new choppers are capable of controlling field current completely separately, while offering capability of bidirectional armature energy flow. To develop the chopper circuit with minimum number of swithcing elements, the complete family of possible conduction circuits are systematically investigated. Then one or two quadrant chopper circuits which offer the desired operations are synthesized from the resulting conduction circuits. Finally, the developed chopper circuits are analyzed in the steady state. The details of operation of the chopper circuits are also fully described and experimented.

• Journal of Digital Convergence
• /
• v.4 no.1
• /
• pp.31-41
• /
• 2006

This article introduces developing trends of an 'Ubiquitous Interface' as an access method for use of various network resources, such as public wireless networks and un-licensed wireless networks in ubiquitous sensor network environments, without troublesome settings or operations by users. 'Ubiquitous Interface' is a relatively wide sense meaning not only physical interface of specified device or between processors, but anything method for access USN. These 'Ubiquitous Interface' able to provide seamless services that adapt autonomously to the user's movements and changes in the state of wireless resources. Recently, strongly recommended current technologies are RFID, NFC, Multi-mode mobile terminal, UMA mobile terminal and Wearable computer as a future ubiquitous interface. These technologies are have to have flexibility and multiple physical communication channels for seamless service hand over and serve easy connection at huge USN to user. Also, they have to must have flexible software structure. Finally, through the 'Ubiquitous Interface', we will be experience of seamless communication and realize a real liberty of communication.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.3
• /
• pp.423-426
• /
• 2015

Current verification methods for on-chip memory have been implemented using coverpoints that are generated based on a single operation. These coverpoints cannot consider the influence of other memory banks in a busy state. In this paper, we propose a method in which the coverpoints account for all operations executed on different memory banks. In addition, a new constrained random vector generation method is proposed to reduce the required random vectors for the multi-operation-based coverpoints. The simulation results on NAND flash memory show 100% coverage with 496,541 constrained random vectors indicating a reduction of 96.4% compared with conventional random vectors.