• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.227-231
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• 2011

An external optical modulation using absorption s in a Fabry-Perot laser diode (FP-LD), has been proposed and experimentally demonstrated for multicasting in a WDM-PON. The center wavelengths of absorption s in an FP-LD move to short-wavelength rapidly by only a small current (~1 mA) injection. If the current injection is stopped, the s move back to the original position. Such a movement of the s can make the FP-LD act as an external optical modulator, which is found to modulate at a maximum modulation speed of 800 Mbps or more. For a multicasting transmitter in a WDM-PON, the proposed modulator can be cost-effectively applied to a multi-wavelength laser source with the same periodicity of the longitudinal mode. Instead of the multi-wavelength laser source, tunable-LDs are used for experiments. The 32 channel multicasting system with the proposed modulator has been demonstrated, showing power penalties of 1.53~4.15 dB at a bit error rate of $10^{-9}$ with extinction ratios better than 14.5 dB at 622 Mbps.

• Journal of electromagnetic engineering and science
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• v.1 no.2
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• pp.176-181
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• 2001

This paper presents the farced resonant characteristics of an electrically small cavity partially filled with dielectric material. The method of moments with Galerkins procedure is used to determine the farced resonant characteristics of the small cavity. In order to obtain the equations of the external reactance gives rise to the farced resonance at a given frequency, the cavity with external reactance can be treated as two-port network which has the admittance parameters. Numerical results show that the forced resonance, series or parallel resonance, can be obtained by the controlling the external reactance. To verify the availability of the theoretical analysis, experiments are carried out for the bakelite as the material by measuring the length of external reactance at operating frequencies.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.119-128
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• 2010

Recently, social network services are rapidly growing and it is estimated that this trend will continue in the future. Social network data can be published for various purposes such as statistical analysis and population studies. When data publication, however, it may disclose the personal privacy of some people, since it can be combined with external information. Therefore, a social network data holder has to remove the identifiers of persons and modify data which have the potential to disclose the privacy of the persons by combining it with external information. The utility of data is maximized when the modification of data is minimized. In this paper, we propose a privacy protection method for social network data that considers both structural and content information. Previous work did not consider content information in the social network or distorted too much structural information. We also verify the effectiveness and applicability of the proposed method under various experimental conditions.

• Journal of Contemporary Eastern Asia
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• v.19 no.2
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• pp.234-263
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• 2020

This study aims to assess the quality of the EU's public diplomacy efforts through social media. Specifically, this research explores the headquarters of European public diplomacy (European External Action Service, EEAS) and its subordinate agent (EU Delegation to South Korea, EUDK). The main research question is "how coherently and effectively does the EU execute public diplomacy strategies in the third countries?'' This study employs both quantitative and qualitative approaches―the former for the results presentation and the latter for the results interpretation. The results are summarized in two points. First, both the EEAS and the EUDK maintained an objective position by posting only neutral perspectives on their social media. Second, the narratives of the main actors were the same, but the main themes were different according to their contexts. The analysis discusses the effectiveness of the EU's strategic narratives by focusing on measuring message reception. Its limited findings were that social media postings could not induce the audiences' active discussion of the EU's diplomatic performances. The conclusion suggests that the EU should identify the expectations from its global counterparts and use these to forge the Union's strategic narratives.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.87-90
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• 2006

Nowadays, we can enjoy access to high speed network and advanced services of convergence between broadcasting and communication anywhere and anytime through a ubiquitous computing. So, now digital convergence devices come out constantly. These devices are required faster network environment for high speed data processing than before. In this paper, we describe the design of InfiniBnad network adapter, which is included two FPGA chipsets. When this adapter is installed to Digital Convergence Platform (DCP) network performance will be improved. The adapter includes 12channel serial ports for external communication and internally, uses PCI-Express bus. We have finished the test of high speed serial based network adapter through composing complete InfiniBand network and applied fabric management software. So, we have verified that it can be applied on DCP environment.

• Convergence Security Journal
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• v.5 no.2
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• pp.19-27
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• 2005

As home network is increasing to use, home network industry is developing too. Also, it is to be a popular subject in the network's topics. In this reasons, home network become a important thing because home gateway function is working between access network and home network. In the home network, it relates on the personal computer, home pad, and digital television. But, home gateway is not prepared standard point about techniques. Therefore, many kind of technique want to try for developing of home gateway's functions. Usually, we use ID/PASSWORD method in network control system. But, we found a lot of problems about classical network system while we experienced Jan/25 big trouble. We are considering about that home network system are using same network net. Therefore, seriously we have to check about security and safety at the home network's environment. This report focus on the home network's environment to control for using and efficiency and then it wants to find ways to protect from the internal and external attacks. Existing ID/PASSWORD method it used a electronic signature and the security against the approach from of external watch, the MIB structure of role base and the security of the Home network which leads the authority control which is safe even from the Home network inside it strengthened it used compared to it proposed.

• Korean Management Science Review
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• v.28 no.1
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• pp.53-60
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• 2011

Time series analysis methods have been traditionally used in stock price prediction. However, most of the existing methods represent some methodological limitations in reflecting influence from external factors that affect the fluctuation of stock prices, such as oil prices, exchange rates, money interest rates, and the stock price indexes of other countries. To overcome the limitations, we propose a network based method incorporating the relations between the individual company stock prices and the external factors by using a graph-based semi-supervised learning algorithm. For verifying the significance of the proposed method, it was applied to the prediction problems of company stock prices listed in the KOSPI from January 2007 to August 2008.

• Journal of Distribution Research
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• v.1 no.2
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• pp.141-172
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• 1996

This study is to investigate global logistics strategies of Korean electronics companies. in terms of service parts. According to the survey, Korean electronics companies were pursuing multi-level global logistics network such as global, continental, national, regional and service center echelon for improving the efficiency of service parts global logistics. Especially there was a tendency of developing new continental distribution centers. And the companies were exploiting efficiency through inventory control by multi-level echelon, demand forecasting by the product life cycle and supply and service lead time management. But there were some insufficient factors for the efficiency of global logistics operation at the construction of worldwide real time logistics information system and pursuit of the efficiency on the whole network including subcontractors. For the future competitive advantage of the Korean electronics companies, the following are suggested: 1) the establishment of arranged logistics channel adjusting each company's global strategy, 2) the construction of worldwide real time logistics information system, 3) the reengineering of all logistics procedures such as order processing, shipping, inventory control, etc., 4) the enhancement of the ratio of the supply from the external companies and the internal manufacturing subsidiaries at each continent, 5) and the pursuit of operational internalization of external subcontractors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1012-1017
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• 2003

The development of a fast, accurate, and inexpensive position-controlled pneumatic actuator that may be applied to a variety of practical positioning applications with various external loads is described in this paper. A novel modified pulso width modulation (MPWM) valve pulsing algorithm allows on/off solenoid valves to be used in place of costly servo valves. A comparison between the system response of standard PWM technique and that of the novel modified PWM technique shows that the control performance is significantly increased. A state feedback controller with position, velocity and acceleration feedback is successfully implemented as the continuous controller. Switching algorithm of control parameter using learning vector quantization neural network (LVQNN) is newly proposed. which estimates the external loads of the pneumatic actuator. The effectiveness of the proposed control algorithms are demonstrated through experiments with various loads.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.86-93
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• 2003

The development of a fast, accurate, and inexpensive position-controlled pneumatic actuator that may be applied to a variety of practical positioning applications with various external loads is described in this paper. A novel modified pulse width modulation (MPWM) valve pulsing algorithm allows on/off solenoid valves to be used in place of costly servo valves. A comparison between the system response of standard PWM technique and that of the novel modified PWM technique shows that the control performance is significantly increased. A state feedback controller with position, velocity and acceleration feedback is successfully implemented as the continuous controller. Switching algorithm of control parameter using learning vector quantization neural network (LVQNN) is newly proposed, which estimates the external loads of the pneumatic actuator. The effectiveness of the proposed control algorithms are demonstrated through experiments with various loads.