• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.20-27
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• 2009

In this paper, HAPS operation scenario is proposed to minimize the interference from HAPS user terminal(HUT) to geostationary earth orbit(GEO) satellite receiver. The conventional scenario has been assumed for fully operated situation of HUT. However, all the HUTs could not be fully operated in a real system operation. Therefore, in order to reduce the interference to other systems, multibeam operation scenarios such as time division and adaptive time division methods are proposed and the interference effect of HUT to satellite receiver is evaluated according to various operation rate of HUT.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.189-196
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• 2011

As internet is getting advanced day by day, digital contents have been developed in various areas as killer content in the IT industry. It needs to develop lots of complicated digital content protect systems due to the enhancement and variety of user's multimedia devices. Although there are lots of protect systems based on DRM(Digital Rights Management) technology, it is difficult to provide secure protection because of the problems resulting from analog hole problem, inefficiency of key sharing and various independent protect technologies. Thus, in this paper, we propose a novel authentication and protect system based on RFID(Radio Frequency Identification) technology to solve the problems and show possibility of free content duplication and efficient contents management in smart home environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.89-95
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• 2003

This paper proposes downlink blocking model and approximation equation using lower bound approximation in order to determine the proper guard band between cdma2000 1X and WCDMA in handover areas. The frequency sharing conditions obtained by the model and approximation equation on blocking probability proposed in the paper, are co-site of base station and guard band higher than 1 MHz. Also, the proposed equation is in the form of Q-function. It is an analytical solution overcoming the drawback of recalculation, belonged to Monte-Carlo technique.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.58-63
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• 2013

Since radio interference can degrade the performance of systems or limit the system operation, an accurate assessment of radio interference with the existing systems should be conducted prior to the operation of a new system. In this paper, we present an evaluation methodology for the radio interference between radio-navigation satellite service (RNSS) systems and mobile communication service (MS) system. Radio interferences from RNSS systems into MS system using minimum coupling loss (MCL) method are simulated and vice-versa, and the frequency sharing condition between two systems are derived in a same geographical area.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.4
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• pp.43-53
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• 2002

In this paper, a new dynamic D-flip-flop which does not suffer from charge sharing and glitch problems is proposed. And a dual-modulus divide-by-128/129 prescaler has been designed with the proposed D-flip-flops using a 0.6$0.6{\mu}m$ CMOS technology. Eleven-transistor architecture enables it to operate at the higher frequency range and the transistor merging technique contributes to the reduction of power consumption. At 5V supply voltage, the simulated maximum operating frequency and the current consumption of the divide-by-128/129 prescaler are 1.97GHz and 7.453mA, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.179-184
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• 2011

In this paper, we analyze the sharing parameters in order to co-use of different communication systems in adjacent channels. We analyze the performance result according to various density of interfering transmitter and transmitter output in hetero systems. In order to get the relationship with between density of interfering transmitter and transmitter output, we consider the case that WiBro is an interfering transmitter an WLAN is a victim receiver. When the center frequency of WLAN is 687MHz and interferer density is 50/$km^2$, required guard band is 10MHz. Analyzed coexistence results may be widely applied into the technique developed to get the coexisting condition for wireless devices using many communication protocols in same frequency.

• Journal of Power Electronics
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• v.9 no.2
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• pp.133-145
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• 2009

In this paper a modular high performance MV-to-LV rectifier based on a cascaded H-bridge rectifier is presented. The proposed rectifier can directly connect to the medium voltage levels and provide a low-voltage and highly-stable DC interface with the consumer applications. The input stage eliminates the necessity for heavy and bulky step-down transformers. It corrects the input power factor and maintains the voltage balance among the individual DC buses. The second stage includes the high frequency parallel-output DC/DC converters which prepares the galvanic isolation, regulates the output voltage, and attenuates the low frequency voltage ripple ($2f_{line}$) generated by the first stage. The parallel-output converters can work in interleaving mode and the active load-current sharing technique is utilized to balance the load power among them. The detailed analysis for modeling and control of the proposed structure is presented. The validity and performance of the proposed topology is verified by simulation and experimental results.

• The Journal of Society for e-Business Studies
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• v.23 no.2
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• pp.1-20
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• 2018

Car Sharing Service is provided with sharing the vehicleas you can use it anywhere and anytime. The paper verified the factors impact between providing infrastructure characteristics such as scarcity, system quality and service quality and user evaluation factors based on DeLone & McLean IS Success Model. User evaluation factors have an influence on net benefit. D&M IS model mainly proved inner organization impact. The research collected experienced car sharing service, we analyzed the 224 respondents. The result of the hypothesis follows. The scarcity of time is negatively related to perceived social support and app trust. Provisional coupon is positively related to perceived social support and app trust. But, scarcity of quantity is not related to user evaluation factors. Most of the system qualities are related to app trust, however, privacy concern isn't related to app trust. the paper's demographic characteristic is lack of experience frequency. User evaluation factors that are perceived social support and app trust are positively related to user satisfaction and WoM intention. User satisfaction is individual impact and WoM intention is organization impact. Two factors are the net benefit in car sharing service. The area of sharing economy should more study about correlation among experimental various factors. Thus, the paper has different significant from antecedent research. because of trying to experimental analysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.1
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• pp.68-75
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• 2012

This paper presents a comparative analysis of the parallel operation of different switches in a DC/DC converter. In high power applications, multi-switch PWM power conditioners may be preferred despite a higher component count, due to the absence of low frequency filters, reduced switching losses and fault tolerance. The paper demonstrates how current sharing (CSH) and time sharing (TSH) lead to the reduction of switching stress in the parallel operation of switches in any converter. The solutions proposed in this study can be applied on different scales to other power conditioners for DC/DC converter systems. Discussions of the concepts, hypotheses and computer simulations are verified by 1 kW experimental results.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.9_10
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• pp.1124-1133
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• 2003

The purpose of this study was to investigate relationships among partnership variables and sourcing performance. Partnership variables were included as: contract conditions, information sharing, communication, conflict, job understanding, monitoring, culture understanding, trust and commitment. Sourcing performance included perceived benefits and sourcing satisfaction. The survey research design was employed with the structured questionnaire. A sample of 104 Korean apparel firms' managers participated in this survey. Apparel firms selected for this study were casual, sports, children's wear firms doing actively international sourcing. For the data analysis, descriptive statistics (i.e., frequency, percent), factor analysis, correlation, and multiple regression analysis were used. Information sharing and job understanding were positively related with trust. That is to say, the better information sharing and the better job understanding apparel firms had higher scores of trust than others. Contract conditions, communication, conflict, and culture understanding were known as predictions of commitment to international outsourcing. The more trust firms had with their vendors, the more commitment the firms had in the international sourcing. This result showed that trust is the essential factor of commitment. Trust and commitment were significantly related with outsourcing performance (i.e., perceived benefits, satisfaction of the international sourcing). Partnership information of international sourcing assembled in the review of literature and the results from this empirical study may assist the domestic apparel firms to make better decision in the adoption process of international sourcing.