• Journal of Information Technology Services
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• v.15 no.1
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• pp.81-96
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• 2016

This study analyzes how breach fee under long-term contract and/or cap regulation on the breach fee can affect the impacts of "Mobile Device Distribution Improvement Act" on handset bundle price, average revenue per unit (ARPU), and social welfare. We conduct comparative analysis with an economic model of duopoly competition in price when users are under long-term contract and the breach fee can be regulated. The results show that the Act lowers the equilibrium prices, lower than incumbent price without the Act. Price of non-dominant Mobile Network Operator (MNO) can be lower than poaching price without the Act if significant portion of switching cost is breach fee or the market is significantly asymmetric. Under the significant circumstances, the Act can raise ARPU even though it improves social welfare. By contrast, the Act increases consumer surplus without affecting social welfare if breach fee is the only source of user's switching cost and is capped by the regulation, and more symmetric market and the stronger cap leads to higher consumer surplus.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.2
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• pp.72-74
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• 2006

In this paper, a wireless multimedia service interacting with key input of a phone number is Presented. In the conventional handset, when the key button is pressed, numbers are displayed or the embedded sound is played. Also, the contents are fixed and cannot be changed. In this paper, we propose a wireless multimedia service playing multimedia contents in accordance with the key input of a phone number. The contents can be downloaded from the wireless internet server. To implement this service, file format, fast codec and download structure are proposed. Using the presented structure, this service is being provided by a telecommunication company in Korea. Various applications based on this service are being expected.

• ETRI Journal
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• v.32 no.1
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• pp.151-153
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• 2010

A highly efficient linear and compactly integrated series-type Doherty power amplifier (PA) has been developed for wideband code-division multiple access handset applications. To overcome the size limit of a typical Doherty amplifier, all circuit elements, such as matching circuits and impedance transformers, are fully integrated into a single monolithic microwave integrated circuit (MMIC). The implemented PA shows a very low idle current of 25 mA and an excellent power-added efficiency of 25.1% at an output power of 19 dBm by using an extended Doherty concept. Accordingly, its average current consumption was reduced by 51% and 41% in urban and suburban environments, respectively, when compared with a class-AB PA. By adding a simple predistorter to the PA, the PA showed an adjacent channel leakage ratio better than -42 dBc over the whole output power range.

• ETRI Journal
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• v.35 no.2
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• pp.321-331
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• 2013

High-tech markets are unpredictable owing to rapid technology innovation, diverse customer needs, high competition, and other elements. Many scholars have attempted to explain the uncertainty in high-tech markets using their own various approaches. However, sufficiently clear ways to predict diverse changes and trends in high-tech markets have yet to be presented. Thus, this paper proposes a new approach model, that is, systematic market segmentation, to give more accurate information. Using an empirical dataset from the mobile handset market in the Republic of Korea, we conduct our research model consisting of three steps. First, we categorize nine basic segments. Second, we test the stability of these segments. Finally, we profile the characteristics of the customers and products. We conclude that the approach is able to offer more diagnostic information to both practitioners and scholars. It is expected to provide rich information for an appropriate marketing mix in practice.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.155-163
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• 2002

In this paper, we propose SAR reduction methods based on power conservation relation, After defining SRF(SAR Reduction Factor) for a more quantitative discussion of effective SAR reduction methods, many kinds of simulation have been performed. We compare the SAR by a flip type handset with that of folder type one. It is found that in a typical position of handsets over a human head, the SAR when using the folder type is about 30 % smaller than that when using the flip type. The effects of ferrite material when using flip type handset are shown to be not considerable when using a folder type.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.1
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• pp.30-33
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• 2008

This paper persents how to port HAL (Handset Abstraction Layer) on embedded Linux to support WIPI (Wireless Internet Platform for Interoperability). As smart phones are widespread nowdays, the operating system is changing from a simple kernel like Qualcomm REX OS to more feature-rich Linux kernel. For this reason, we investigate the internal structure of HAL on REX OS and design how to port it to embedded Linux. Careful analysis leads us to identify several porting issues such as thread support, graphical user interface. In addition, we describe some problems discovered during the implementation process and propose alternative architecture of HAL for WIPI on Linux.

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.151-155
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• 2010

Reconfigurable radio technology is needed to reconstruct frequency and modem functionality, which can be different in various regions. In addition, it makes a single mobile handset capable of supporting various standards of wireless communication and thus plays a key role in mobile convergence. An MMIC VCO (voltage controlled oscillator) has been developed for high power and wide bandwidth where Clapp-Gouriet type oscillators are adapted for series feedback, and was fabricated based on 0.15um pHEMT of TRW. The MMIC VCO was connected to an aluminar substrate on the carrier for testing. This MMIC VCO module showed good performance in comparison to existing works. Furthermore, it can be potentially extended to reconfigure an MMIC VCO for wireless systems such as military applications and satellite communications.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.622-627
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• 2014

A method to reduce the specific absorption rate(SAR) of the antenna for WiMAX mobile communication is proposed in this paper. The SAR reduction is achieved by miniaturizing the physical size of the antenna for the given resonance frequency by devising a metamaterial-composite right- and left-handed(CRLH) configuration-based radiator much smaller than the quarter-guided wavelength adopted a lot in the conventional planar inverted F antenna(PIFA) or modified monopole antenna. The proposed antenna is placed near the head-phantom and its SAR is evaluated by the full-wave simulations(SEMCAD X), where the metamaterial-inspired antenna is shown to have the lower value than a modified monopole as the reference in terms of the SAR.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.1024-1027
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• 2011

본 논문은 HD (High-definition) video, SD (Standard-definition) video, low quality video, handset video, 4 가지 Imaging Device 에 대한 프로파일 분석을 통해 비디오 프레임 상에 나타나는 위 변조를 검사하는 방법을 제안한다. High-definition video, Standard-definition video, low quality video, handset video 에 대한 분석을 하고 각 영상의 특이 점을 파악 하여 분류한 클래스에 대한 프로파일검사를 통해 EM Algorithm 을 이용하여 영상의 위 변조를 검사 하고 영상의 신뢰성을 높인다.

• 한국ITS학회:학술대회논문집
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• 2003.11a
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• pp.217-220
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• 2003