• The Journal of Society for e-Business Studies
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• v.20 no.4
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• pp.193-208
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• 2015

In knowledge based society, information technology (IT) has been playing a key role in economic growth. In recent years, it is surprisingly notable that the source of value creation moved from hardware to software in IT industry. Especially, among many kinds of software products, the economic potential of open source was realized by many government agencies. Open source means software codes made by voluntary and open participation of worldwide IT developers, and many policies to promote open source activities were implemented for the purpose of fast growth in IT industry. But in many cases, especially in Korea, the policies promoting open source industry and its ecosystem were not considered successful. Therefore, this study provides the practical reasons for the low performance of Korean open source industry and suggests the pragmatic requisites for effective open source policy. For this purpose, this study applies soft system model (SSM) which is frequently used in academy and industry as a methodology for problem-solving and we link the problems with corresponding policy solutions based on SSM. Given concerns which Korean open source faces now, this study suggests needs for the three different kinds of government policies promoting multiple dimensions of industry: research and development (R&D)-side, supply-side, and computing environment-side. The implications suggested by this research will contribute to implement the practical policy solutions to boost open source industry in Korea.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1589-1596
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• 2013

Recently, spectral efficiency or reliability is required to be improved in the scenario of multiple access. In this paper, we consider a scenario where two source nodes access one destination node. Different with conventional multiple access studies, in our research, a part of the allocated resource is shared by two source nodes and this scheme is called partial multiplexing. Let $R_s$ denote the ratio of the amount of the shared resource to that of the resource allocated to each user. We analyze and optimize the performance of the partial multiplexing in term of $R_s$. We show that the optimal $R_s$ to maximize the throughput is 1 or 0 based on approximated bit error rate (BER). In addition, if we set a constraint on frame error rate (FER), $R_s$ can have a value between 0 and 1. We also find the approximated $R_s$ to meet the constraint as a closed form. Partial multiplexing can be a novel multiple access scheme.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.55-62
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• 2000

In constructing a synthetic seismogram using ray-tracing method a suite of ray-code is required to obtain a realistic seismogram which is similar to the actual seismogram or earthquake record under consideration. An infinite number of rays exist for any arbitrarily located source and receiver. One select only a finite number of such rays in computing a synthetic seismogram so their selection becomes important to the validity of the seismogram being generated. Missing certain important rays or an inappropriate selection of ray-codes in tracing rays may result in wrong interpretation of the earthquake record or seismogram. Automatic ray-code generation will eliminate such problems. In this study we have developed an efficient algorithm, with which one can generate systemastically all the ray-codes connecting source and receiver arbitrarily located. The result of this work will helpful in analysing multiple reflections in seismic data processing as well as simulating Lg wave and multiply reflected or converted phases in earthquake study.

• Journal of Korea Multimedia Society
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• v.18 no.4
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• pp.533-540
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• 2015

We study relay selection in decode-and-forward (DF)-based relay networks consisting of a source, a destination, an eavesdropper, and multiple relays, where each terminal has a single antenna and operates in a half-duplex mode. In these networks, it is desirable to protect the confidential message from the source to the destination against the eavesdropper with the help of a single selected relay. Specifically, we begin by investigating DF-based networks for the scenario instantaneous signal-to-noise ratios (SNRs) related to the eavesdropper are available. For the scenario, we propose relay selection to maximize the secrecy rate of DF-based networks with and without direct-paths, and we derive the exact secrecy outage probabilities in closed-form.

• ETRI Journal
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• v.36 no.1
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• pp.183-186
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• 2014

In this letter, we consider a cooperation system with multiple untrusted relays (URs). To keep the transmitted information confidential, we obtain joint channel characteristics (JCCs) through combining the channels from the source to the destination. Then, in the null space of the JCCs, jammers construct artificial noise to confuse URs when the source node broadcasts its data. Through a distributed implementation algorithm, the weight of each node can be obtained from its own channel state information. Simulation results show that high-level security of the system can be achieved when internal and external eavesdroppers coexist.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.1
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• pp.61-71
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• 1998

The purpose of this study was to identify the factors which explain consumer's information search behavior. Data were analyzed by utilizing factor analysis and multiple-regression to investigate the relationship among information sources, benefit, and actual and ideal self- image and demographics. Based on the results, information sources for benefit, actual and ideal self-image were developed. Predictors of information sources, benefits, and self-image were identified. Marketing implication about information sources were discussed. The results were as follows. 1. Actual and ideal self-images and information sources were devised into three factors. And benefits were devised into five factors. 2. Actual self-image has more predicting power than ideal self-image to the benefits which consumer sought. Among five benefits, character pursuit was the best predicted factor according to the self-image. 3. Among three information sources, mass communication was the most effective source which can be explained by the benefit and self-image. Fashion pursuit factor was the most significant factor to the mass communication oriented source.

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.328-335
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• 2005

This paper proposes a frequency domain independent component analysis (ICA) algorithm to separate the mixed speech signals using a multiple microphone array By estimating the delay timings using a input cross-correlation, even in the delayed mixture case, we propose a good initial value setting method which leads to optimal convergence. To reduce the calculation, separation process is performed at frequency domain. The results of simulations confirms the better performances of the proposed algorithm.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1504-1512
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• 2016

This paper presents a new single-phase asymmetrical cascaded multilevel DC-link inverter. The proposed inverter comprises two stages. The main stage of the inverter consists of multiple similar cells, each of which is a half-bridge inverter consisting of two switches and a single DC source. All cells are connected in a cascaded manner with a fixed neutral point. The DC source values are not made equal to increase the performance of the inverter. The second circuit is a folded cascaded H-bridge circuit operating at a line frequency. One of the main advantages of this proposed topology is that it is a modular type and can thus be extended to high stages without changing the configuration of the main stage circuit. Two control schemes, namely, low switching with selective harmonic elimination and sinusoidal pulse width modulation, are employed to validate the proposed topology. The detailed approach of each control scheme and switching pulses are discussed in detail. A 150W prototype of the proposed system is implemented in the laboratory to verify the validity of the proposed topology.

• Journal of Plant Biotechnology
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• v.3 no.3
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• pp.141-144
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• 2001

To enhance the shoot induction efficiency from nodal stem of yooza, the culture conditions such as basal medium, carbohydrate source, solidifying agent and the optimum concentration of plant growth regulators for shoot induction were investigated. The nodal explants were cultured better on MS medium than on MT, SH, B5 or W media in considering of shoot induction rate and mean shoot length. Solidifying agent in medium was better with 0.8% agar than with 0.3% agar, 1.2% agarose or 0.2% gelrite. Carbohydrate source in shoot induction medium was efficient with 30 g/L sucrose. The optimum concentrations of plant growth regulators were determined that 0.1 mg/L NAA as auxin was effective on the shoot induction, and 1.0 mg/L BAP as cytokinin induced multiple shoots efficiently. Shoot induction was the most effective on MS medium supplemented with 4 mg/L $GA_3$ in yooza.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.533-534
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• 2006

Micro-source units having power ratings in thousands of watts can provide power quality with higher reliability and efficiency than the conventional large scale units. This paper develops switching level model of micro-source and studies the characteristics of the micro-grid consisting of multiple micro-sources and interfaced with electric power system. The developed model adopts the space vector PWM to fully utilize the capacity of inverter. The interaction of the grid connected micro-sources and the characteristics of the control system parameters are investigated. Micro-sources and micro-grid are implemented using PSCAD/EMTDC. Simulation results show that the proposed model is efficient for studying micro-grid system.