• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.181-188
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• 2005

In this paper, a DC smoothing filterless soft switching pulse modulated high frequency AC power conversion circuit connected to utility. frequency AC power source is proposed for consumer induction heating hot water producer, steamer and super heated steamer. The operating principle of DC link filterless utility frequency AC-high frequency AC (HF AC) power conversion circuit defined as high frequency cycloinverter is described, which can operate under a principle of ZVS/AVT and power regulation based on alternate asymmetrical PWM in synchronization with the utility frequency single phase AC positive or negative half wave voltage. The dual mode modulation control scheme based on high frequency PWM and commercial frequency AC voltage PDM for the proposed high frequency cycloinverter are discussed to enlarge its soft switching commutation operating range for wide HF AC power regulation. This high frequency cycloinverter is developed for high frequency IH Dual Packs Heater (DPH) type boiler used in consumer and industrial fluid pipeline systems. Based on the experiment and simulation results, this high frequency cycloinverter is proved to be suitable for the consumer use IH-DPH boiler and hot water producers. The cycloinverter power regulation and power conversion efficiency characteristics are evaluated and discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.778-798
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• 2014

This paper proposes a novel exposed-terminal-eliminated medium access control (ETE-MAC) protocol by combining channel reservation, collision avoidance and concurrent transmissions to improve multi-access performance of the multihop wireless networks. Based on the proposed slot scheduling scheme, each node senses the control channel (CCH) or the data channel (DCH) to accurately determine whether it can send or receive the corresponding packets without collisions. Slot reservation on the CCH can be simultaneously executed with data packet transmissions on the DCH. Therefore, it resolves the hidden-terminal type and the exposed-terminal type problems efficiently, and obtains more spatial reuse of channel resources. Concurrent packet transmissions without extra network overheads are maximized. An analytical model combining Markov model and M/G/1 queuing theory is proposed to analyze its performance. The performance comparison between analysis and simulation shows that the analytical model is highly accurate. Finally, simulation results show that, the proposed protocol obviously outperforms the link-directionality-based dual-channel MAC protocol (DCP) and WiFlex in terms of the network throughput and the average packet delay.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.43-49
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• 2009

The Mobile IPv6(MIPv6) has a well-known time gap of packet loss between link down and binding update. To minimize such packet loss, this paper proposes a MIPv6-based dual tunneling mechanism, which keeps exploiting the old tunnel while creating a new tunnel. Superiority of the proposed mechanism is evaluated by quantitative analysis on the lost packets and computer simulation, based on two overlay heterogeneous access networks, such as the UMTS and a WLAN.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.136-143
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• 2010

In this paper, we investigate decode-and-forward (DF) relaying systems with a direct link between the source and the destination node. The objective of this paper is to determine the better relaying strategy between 3-hop DF relaying and dual-hop DF relaying with the best relay selection. Assuming Rayleigh fading channels, we present closed-form outage probability of the 3-hop relaying and the dual-hop relaying, respectively, and compare the performances by numerical investigation. Numerical results show that if the channel is poor, the outage performance of the 3-hop relaying is better than the dual-hop relaying.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.4
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• pp.81-88
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• 2005

This paper attempts to derive the dynamic model of handling tasks in finger robot which grasps stable and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraint of tight area-contacts is formulated by Lagrange's equation. Secondly, the roblems of controlling both the forces of pressing object and the rotation angle of the object under the geometric constraints are discussed. The effect of geometric constraints of area-contacts between the link's end-effector and the object is analyzed and the model based on the differential-algebraic equations is presented. In this paper, the control method for dynamic stable grasping and enhancing dexterity in manipulating things is proposed. It is illustrated by computer simulation and the experiment that the control system gives the performance improvement in the dynamic stable grasping and nimble manipulating of the dual fingers robot with soft tips.

• Steel and Composite Structures
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• v.30 no.4
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• pp.365-382
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• 2019

In steel frame-tube structures (SFTSs) the application of flexural beam is not suitable for the beam with span-to-depth ratio lower than five because the plastic hinges at beam-ends can not be developed properly. This can lead to lower ductility and energy dissipation capacity of the SFTS. To address this problem, a replaceable shear link, acting as a ductile fuse at the mid length of deep beams, is proposed. SFTS with replaceable shear links (SFTS-RSLs) dissipate seismic energy through shear deformation of the link. In order to evaluate this proposal, buildings were designed to compare the seismic performance of SFTS-RSLs and SFTSs. Several sub-structures were selected from the design buildings and finite element models (FEMs) were established to study their hysteretic behavior. Static pushover and dynamic analyses were undertaken in comparing seismic performance of the FEMs for each building. The results indicated that the SFTS-RSL and SFTS had similar initial lateral stiffness. Compared with SFTS, SFTS-RSL had lower yield strength and maximum strength, but higher ductility and energy dissipation capacity. During earthquakes, SFTS-RSL had lower interstory drift, maximum base shear force and story shear force compared with the SFTS. Placing a shear link at the beam mid-span did not increase shear lag effects for the structure. The SFTS-RSL concentrates plasticity on the shear link. Other structural components remain elastic during seismic loading. It is expected that the SFTS-RSL will be a reliable dual resistant system. It offers the benefit of being able to repair the structure by replacing damaged shear links after earthquakes.

• Journal of Technology Innovation
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• v.14 no.3
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• pp.209-235
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• 2006

Since the end of the cold war, technical tie-up between private corporations and an army in developed countries has increased a lot, and the trend is spreading through developing countries rapidly. To cope with the circumstance actively, the dual use technology program for both private corporations and an army was begun in Korea in 1998. With the program, overlapping investment was resolved and technology transfer was stimulated. And the standardization and information exchange saved considerable national budget and made possible economic profit. Yet, the combination project of 4 ministries and offices showed problems such as loose cooperation and, low industralization record. However, developed countries are out of the mere stage of dual technology development and turn into broad technical tie-up including future prediction, national competitiveness improvement, and the private company's leading participation and they are systemizing them very fast. Korea also set up the national defense reform plan with the blueprint of future military force improvement, budget increase for national defense research, and increased participation of private corporations, and created Defense Acquisition program Administration to support them. The innovation of national defense system brings forward the need to link the private and military innovation. Korea has pursued the fast growth through assimilation, absorption, and improvement of foreign technology. But now, Korea has to focus on self innovation, original technology, parts and material. As this applies to private companies and military equally, it is important to concentrate limited resources for the effective technology cooperation. Considering this, the strategies to activate the dual use technology are program concept and range extension, task-deduction way improvement and future-oriented common task deduction, and promotion system improvement.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.2
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• pp.105-115
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• 2002

Since NUMA architecture has to access remote memory an interconnection network determines the performance of CC-NUMA system Bus which has been used as a popular interconnection network has many limits to build a large-scale system because of the limited physical scalabilty and bandwidth Dual ring interconnection network composed of high speed point-to-point links is made up for resolving the defects of the bus for large-scale system But it also has a problem that the response latency is rapidly increased when many node are attached to snooping based CC-NUMA system with dual ring In this paper we propose a chordal ring architecture in order to overcome the problem of the dual ring on snooping based CC-NUMA system and design and efficient link controller adopted to this architecture. We also analyze the effects of chordal ring architecture on the system performance and the response latency by using probability driven simulator.

• Journal of the Korea Society of Computer and Information
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• v.24 no.11
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• pp.71-78
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• 2019

Most 3D displays that are currently in the market adopt the binocular disparity method creating a different image for the left and right eye for a 3 dimensional effect. However, commercialized 3D image output devices lack in performance making it uncomfortable for the viewer and restrict the viewer to certain positions. In this paper, we propose a single-cell polarized lens type stereoscopic system which has a smaller viewing angle and reduced crosstalk, with improved light penetration compared to existing double-cell structures; and analyzed the single-cell polarized lens type stereoscopic system properties, and conducted an effect analysis of performance improvement compared to the dual-cell type. Results showed that the single-cell type had a 25% improved performance, and the 3D crosstalk index which is an important index for quality characteristics of stereoscopic systems, increased over about 37%, compared to the dual-cell type.

• Industry Promotion Research
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• v.9 no.3
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• pp.119-127
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• 2024

This study aims to confirm the dual mediating effect of gratitude and mindfulness in the relationship between grit and flourishing in middle and high school students and to provide basic data that can improve flourishing. The study subjects were middle and high school students who were selected from a city in South Chungcheong Province, and data were collected through a survey. For data analysis, SPSS PC+ Win. ver. 25.0 and SPSS PROCESS macro ver. 4.2 were utilized. Data were analyzed using descriptive statistics, reliability analysis, correlation analysis, and dual mediation effect analysis techniques. First, correlation analysis showed that there was a significant and positive correlation between grit, gratitude, mindfulness, and flourishing and the highest correlation between gratitude and mindfulness. Second, gratitude and mindfulness had a serial dual mediating effect in the link between grit and flourishing in middle and high school students. These results can be used as a new model to improve flourishing by utilizing positive psychological variables such as grit, gratitude, and mindfulness for middle and high school students.