• Journal of Powder Materials
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• v.10 no.3
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• pp.172-175
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• 2003

Mechanically-alloyed NiAl powder was sintered by Spark-Plasma Sintering (SPS) process. Densification and behavior mechanical property were determined from the experimental results and analysis ,such as changes in linear shrinkage, shrinkage rate, microstructure, and phase during sintering process, Victors hardness, and transver.ie-rupture-strength (TRS). Above 97% relative density was obtained after sintering at 115$0^{\circ}C$ for 5 min. Crystallite size determined by the Scherrer method was approximately 50 nm. From the X-ray diffraction analysis it was confirmed that the sintered bodies were composed mainly of NiAl phase together with Ni$_3$Al phase. Measured Vickers hardness and TRS value were 555$\pm$10 $H_v$ and 1393$\pm$75 MPa , respectively.

• 전자공학회논문지 IE
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• v.48 no.3
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• pp.20-25
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• 2011

We developed a method of accelerating the operation speed of communication systems for SDR(Software Defined Radio) systems in WiBro environment. In this paper, we propose a new scheme of using GPU(Graphics Processing Unit) for implementing the communication system which perform with the functionality of SDR. In general, communication systems is made by DSP(Digital Signalling Processor) or FPGA(Field Programmable Gate Array). However, in this case, there are exist the problem of implementation and debugging caused by each CPU characteristic. The GPU is optimized for vector processing because it usually consists of multiple processors and each processor in GPU is composed of a set of threads. We also developed Framework to use GPU and CPU resources effectively for reducing the operation time. From the various simulation, it is confirmed that GPU system have good performance in WiBro system.

• 전자공학회논문지 IE
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• v.48 no.3
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• pp.10-15
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• 2011

In the case of designing an acoustic transducer for high power application, we usually aim to transfer the source electric energy to the output acoustic energy as large as possible. For this purpose, we should match the impedance of the power amplifier to the impedance combined with the acoustic transducer impedance and the radiation impedance. Especially if we have electrical source with almost zero impedance, we need improve the power factor of the acoustic transducer in the load. In this paper, we propose a broad band impedance matching method by the improvement of power factor, which applies ABCD matrix.

• 전자공학회논문지 IE
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• v.48 no.2
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• pp.52-60
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• 2011

RFID is method used on wireless system. However, this mechanism is not used for authentication and security. Therefore, it is very vulnerable to attacks such as dropping attacks and traffic attacks. the RFID Tags are of the limited nature due to environment factors and there is greater constraints in designing authentication protocol. If we do not RFID to secure corporate information and product all the information will be exposed. The attacker will break into the RFID system and stop the distribution system. So, this paper proposes a new authentication protocol which provides not only unlimited access to Tag&Reader and connection between Tag and Reader bet also provides authentication mechanism by defining the key distribution.

• 전자공학회논문지 IE
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• v.48 no.2
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• pp.19-25
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• 2011

This paper presented neural network modeling method using vehicle data to predict fuel consumption. To acquire data for training and testing the proposed neural network, medium-class gasoline vehicle drove at downtown and parameters measured include speed, engine rpm, throttle position sensor (TPS), and mass air flow (MAF) as input data, and fuel consumption as target data from OBD-II port. Multi layer perception network was used for nonlinear mapping between the input and the output data. It was observed that the neural network model can predict the vehicle quite well with mean squared error was $1.306{\times}10^{-6}$ for the fuel consumption.

• 전자공학회논문지 IE
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• v.47 no.3
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• pp.14-18
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• 2010

In this paper, we describe a CMOS DC-DC converter with a variable output voltage(5-7V @100mA) for a portable battery-operated system applications. The proposed DC-DC converter is used along with a Pulse-Frequency Modulation (PFM) method and consists of reference circuit, a feedback resistor, a controller, and an internal oscillator. The integrated DC-DC converter with two external passive components(L,C) has been designed and fabricated on a 0.5um 2-poly 3-metal CMOS process and could be applied to the Personal Digital Assistants(PDA), cellular Phone, Laptop Computer, etc.

• 전자공학회논문지 IE
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• v.44 no.1
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• pp.15-19
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• 2007

A study to have read does an improvement of an error restoration technology based on the edge direction interpolation that a stop image cared for inside frame correction more than with an image restoration way of a transfer error or with an aim. A way proposed to is based on edge direction detection method of a block utilizing the edge direction which will adjust a part damaged a sweater to a remaining part here. The rest of error pixel used non linear Midian filter for process later data information by the final stage and did interpolation. The examination result shows a good recuperation tendency and low accounts time of a way proposed to realization possibility of a real time image processing.

• Korean Institute of Interior Design Journal
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• v.18 no.3
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• pp.84-92
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• 2009

Sociological, technical, and organizational changes have affected the culture of business in many ways. These changes are now encouraging new concepts in the workplace environment such as emotional approaches for a more creative and humanistic workplace let alone enhancing image of the company. The aim of this study is to understand current situations of common office areas and serve as a stepping stone for designing more creative and stimulating work environments. The study first examines concepts of new office designs in our modem society, then defines categories such as territorial fuzziness, eco-friendly, fun and play. Secondly, by using content analysis as research tool the researchers have investigated how the conceptual categories and detailed design presentation methods are shown in workplace designs in Korea. Scope of study is limited to 39 office design projects from 2002-2008 presented in the Korean monthly magazine 'Interiors'. As results. territorial fuzziness was found to be most popular method while play the least. For application wise, meeting rooms, rest area and hallways were places where these concepts appear the most. Even though, these new approaches in office designs can be found in our domestic offices, still more experimental and active approach seems to be needed.

• IE interfaces
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• v.16 no.spc
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• pp.21-27
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• 2003

Objective of this paper is to develop the user mobility model(UMM) which is used for the performance analysis of location update and paging algorithm and at the same time, consider the user mobility pattern(UMP) in zone-based cellular networks. User mobility pattern shows correlation in space and time. UMM should consider these correlations of UMP. K-dimensional Markov chain is presented as a UMM considering them where the states of Markov chain are defined as the current location area(LA) and the consecutive LAs visited in the path. Also, a new two dimensional Markov chain composed of current LA and time interval is presented. Simulation results show that the appropriate size of K in the former UMM is two and the latter UMM reflects the characteristic of UMP well and so is a good model for the analytic method to solve the performance of location update and paging algorithm.

• IE interfaces
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• v.19 no.3
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• pp.255-269
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• 2006

Digital manufacturing(DM) is the ability to describe every aspect of the design-to-manufacture process digitally-using tools that include digital design, CAD, office documents, PLM(Product Life-cycle Management) systems, analysis software, simulation, CAM software and so on. The major automotive companies are already deeply invested in DM with almost every process being digital rather than paper-based. But it has taken a long time for the digital process to mature into something usable and there have been some major barriers that have prevented from the DM becoming a reality. Thus many companies hesitate to make a decision of implementing the DM. This paper deals with a study investigating which factors are important for implementing the DM to industries successfully. The extended technology acceptance model (ETAM) is used as the relation model of cause and effect. The quality of hardware, the quality of software, the range of collaboration among companies and the preference of the user are defined as the external factors. Interview method is used for gathering input data, and the results are analyzed with SPSS. The results indicate that four external factors are effective on the successful implementation of DM, and the perceived usefulness is most important.