• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.2
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• pp.94-100
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• 1988

Recently with the rapid development in marine and shipbuilding industries such as marine structures, ship, and chemical plants, there occurs much interest in the study of corrosion fatigue characteristics was closed up an important role in mechanical design. In this study, the 5086 Al-Alloy was tested by used of a rotary bending fatigue tester and was investigated under the environments of various specific resistance and air. The specific resistance, as a corrosion environment, was changed 15, 20, 25 and 5000$\Omega$.cm. The corrosion fatigue crack initiation sensitivity was quantitatively inspected for 5086 Al-Alloy in the various specific resistance. The experimental constants of Paris rule were examined in the various specific resistances, and the influences of load and corrosion with affect the crack growth rate were compared with. Main results obtained are as follows: (1) Number of stress cycles to corrosion fatigue crack initiation delaies and corrosion fatigue crack initiation sensitivity decreases with the increasing for the specific resistance. (2) The experimental constant m of Paris rule decreases with the decreasing for specific resistance. Hence the effect of corrosion is more susceptible than that of stress intensity factor. (3) The corrosion fatigue crack of 5086 Aluminium Alloy appears intergranular fracture. (4) Corrosion sensitivity is decreased with the increasing stress intensity factor and is nearly uniform when stress intensity factor is over 40kg.mm super(-3/2)

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.345-354
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• 2005

Since motion estimation and motion compensation methods remove the redundant data to employ the temporal redundancy in images, it plays an important role in digital video compression. Because of its high computational complexity, however, it is difficult to apply to high-resolution applications in real time environments. If we have a priori knowledge about the motion of an image block before the motion estimation, the location of a better starting point for the search of an exact motion vector can be determined to expedite the searching process. In this paper presents the motion detection algorithm that can run robustly about recusive motion. The motion detection compares and analyzes two frames each other, motion of whether happened judge. Through experiments, we show significant improvements in the reduction of the computational time in terms of the number of search steps without much quality degradation in the predicted image.

• Journal of Korea Multimedia Society
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• v.2 no.3
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• pp.329-338
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• 1999

In this paper we propose a WATM MAC protocol called DTDD/PS (Dynamic Time Division Duplex using Poll/Select scheme). The idea of the DTDD/PS protocol is based that a radio cell is considered as queueing system. The MAC controller in base station is charged in coordinating terminals for the QoS requirement from each terminal. For that reason, terminals send it's own dynamic parameter represented its status, and controller controls the access of terminals and assigns time slots dynamically using received parameters. Therefore this system can satisfy the QoS of real-time service in wireless environments. To evaluate DTDD/PS protocol simulations are executed. In 25Mbps channel capacity, the voice and data coexist traffic situation, as the total number of terminal is increased, the delay of data terminals is increased rapidly. But the case of only increasing data terminals, the number of supported voice terminals is not varying. Therefore we can expect that DTDD/PS protocol can applied to multimedia traffic effectively.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.1
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• pp.37-48
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• 2011

Sensor networks monitor the environment, collect sensed data, and relay the data back to a collection point. Although sensor nodes have very limited hardware resources, they require an operating system that can provide efficient resource management and various application environments. In addition, the wireless sensor networks require the code update previously deployed to patch bugs in program and to improve performance of kernel service routines and application programs. This paper presents EPRCU (Easy to Perform Remote Code Update), a new operating system for wireless sensor nodes, which has enhanced functionalities to perform remote code update. To achieve an efficient code update, the EPRCU provides dynamic memory allocation and program memory management. It supports the event-driven kernel, which uses priority-based scheduling with the application of aging techniques. Therefore, the proposed operating system is not only easy to perform wireless communication with the remote code update but also suitable for various sensor network applications.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.131-138
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• 2010

As ubiquitous computing environments evolve, various services are being provided as customer-centric services. In the past, studies based on personal profiles have been conducted to provide personalized services. However, identifying the user's preferences and supporting personalized services requires considerable data and time. To solve these problems, this paper proposes a system which provides the service by analyzing the user's emotions, rather than personalized service with personal profiles. In the proposed system, both speech analysis method and image analysis method are used to analyze the user's emotion. By using this emotion analysis method, we implemented the proposed system within the home network environment and finally provide effective personalized service.

• Research in Community and Public Health Nursing
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• v.24 no.2
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• pp.185-194
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• 2013

Purpose: This study was to explore situations that might put the middle-aged Korean-Chinese female migrant workers at risk for work-related musculoskeletal diseases (WMSDs). At the development phase of a continuing health project, the study aimed to clarify health promotion program needs of the migrant population. Methods: A qualitative description research design was used with three focus groups of 23 Korean-Chinese female migrant workers. Each focus group interview was conducted for 70-minutes using semi-structured interview guidelines. The data were analyzed using directed qualitative content analysis techniques. Results: The majority of the participants were household workers and their work included heavy material handling, standing for a long time, and working in awkward postures. They experienced discrimination from employers, lack of control at work, limitations in open-communication, job insecurity, and acculturation. They had needs to have health promotion programs for preventing and managing chronic diseases, depression and menopause as well as WMSDs. Conclusion: The participants were situated in work environments with physical demanding tasks, acculturative and job-related stress and lack of opportunities to participate in health promotion programs. It is suggested to develop a comprehensive program to better meet the needs of middle-aged Korean-Chinese female migrant workers rather than targeting the reduction of WMSDs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.7
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• pp.515-522
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• 2018

An orthogonal frequency division multiplexing with coded direct index modulation(OFDM-CDIM) system that can achieve higher performance and spectral efficiency than previous OFDM systems is proposed. Previous OFDM with index modulation(IM) and OFDM-IM using dual modes systems allocate additional data to indices of respective subcarriers through combining operation with high complexity and then transmit them. However, the proposed system directly allocates the mode selection information to each subcarrier without performing additional operations. Then, the system selects and transmits one symbol in the selected mode. Furthermore, only the data allocated to the index of the subcarrier is encoded, and a good performance improvement effect is obtained with a high code rate. Simulation results show quantitatively that an OFDM-CDIM system using four modes improves bit error rate performance and transmission efficiency in additive white Gaussian noise and Rayleigh fading channel environments compared with a conventional OFDM system using 4-ary quadrature amplitude modulation.

• Journal of Korea Multimedia Society
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• v.2 no.4
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• pp.459-467
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• 1999

With fully harnessing the functions provided by Windows NT, we suggest the generating method of RPL profile and the RPL protocol for remote booting on DL-NCS(Network Computing System for Diskless client PCs). This system can offer clients, without having hard disk, boot remotely Window 9x stored in server's hard disk and can share peripheral devices and application programs in the server side. For booting Window 9x from DL-NCS, twenty-five clients' PCs were set for simultaneous on and finally the PCs were booted in similar time interval compared to that from a desktop PC having local disk. This system was also experimented to the application programs. And this system can yield excellent networking environments. In sum, with using this DL-NCS, we can reduce the installing costs of peripheral device, recycle the lower grade PCs such as 486SX/DX, and save the budgets for software purchase.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.581-586
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• 2015

In this paper, we configure a Radio Frequency IDentification (RFID) gateway using an arduino and raspberry pi which are recent issues with a representative open source hardware. RFID technology is emerging as a key technology in a variety of environments as a technique to automatically identify objects using a radio frequency signal. In this paper, we propose a distributed RFID gateway for providing various communication methods and processing a large amount of RFID tag information efficiently, and to increase the scalability and middleware communication efficiency of the RFID reader. Existing RFID middleware systems have the problems that they should adhere the web service for interworking with a reader and the communication standard. Therefore, in this paper, we comprise our RFID gate to satisfy not only the serial communication configuration but also various digital signal processing standard so that it increases the communication efficiency of the middleware system.

• Journal of Advanced Navigation Technology
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• v.18 no.2
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• pp.191-199
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• 2014

Recently, researches to facilitate utilization by small and medium business (SMB) of cloud computing and big data paradigm, which is the booming adoption of IT area, has been on the increase. As one of these efforts, in this paper, we design and implement the prototype to tentatively build up Hadoop cluster under private cloud infrastructure environments. Prototype implementation are made on each hardware type such as single board, PC, and server and performance is measured. Also, we present the integrated verification results for the data analysis performance of the analysis software system running on top of realized prototypes by employing ASA (American Standard Association) Dataset. For this, we implement the analysis software system using several open sources such as R, Python, D3, and java and perform a test.