• Journal of the Korea Society of Computer and Information
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• v.24 no.6
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• pp.205-210
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• 2019

The purpose of this study is to demonstrate empirically whether replacement intervals of mobile phones sold in China online B2C are influenced by purchase points such as holidays. If there is a holiday effect, it is expected that the product replacement interval or interpurchase interval will be short compared to the usual one at holiday time. In order to verify this positively, at TMall, one of the largest B2C sites in China, we explored 5,132 replacement cycle intervals and the point of purchase at which one of the sales records of an agent dealing with all multinational mobile phones had minimum two purchase records. As a result, there was a buyer who had shorter replacement period than usual in holiday season. There was no statistically significant difference in the intervals of interchange between holidays. Based on the results, it was found that the mobile phone vendors were aware that purchasing was occurring due to the holiday.

• ETRI Journal
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• v.32 no.2
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• pp.255-264
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• 2010

Interference scenarios and methodologies between a terrestrial mobile service (MS) system and mobile-satellite service (MSS) system in a co-channel environment are established. Taking into account a practical deployment situation for both systems, we perform computational simulation of interference in terms of carrier-to-interference ratio (C/I) and interference-to-noise ratio (I/N) to evaluate the cofrequency interference from an MS system into an MSS system, and from an MSS system into an MS system, respectively. The methodology and results can be used as a guide when planning the deployment of MSS and MS systems with no unacceptable interference impact between them.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.433-436
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• 1999

In this paper we applied TVS(Triangular Voltage Sweep) method to calculate the mobile ionic charge densities in some ferroelectric thin films. During the measurement, the temperature of specimens were maintained at 20$0^{\circ}C$. By this method, the amount of mobile ionic charge Q$_{m}$ and mobile ionic charge density N$_{m}$ of a MFIS structure were calculated 3.5 [pC] and about 4.3$\times$10$^{11}$ [ions/cm$^2$], respectively. In order to successful TVS measurement, the gate leakage current density of films must be low 10$^{-9}$ (A/cm$^2$) order.der.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.76-78
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• 2002

Multicasting over mobile IP network becomes more important with the increasing needs of supporting multimedia services in mobile network. The IETF has suggested two approaches which are remote subscription and bidirectional tunneling for supporting mobility management in multicasting over mobile IP. But these protocols have problems - the frequent reconstruction of multicast delivery tree, packet less during handoff, convergence problem, and so on. In this paper, we propose to use preconfiguration of multicast delivery tree when mobile host enters the foreign network. It will decrease the frequency of multicast delivery tree reconstruction, and reduce the packet loss during handoff, Also the multicast delivery tree maintained by Keep Alive messages makes the signaling overload of networks diminished.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.667-676
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• 2001

We have solved a problem occurring in case that RSVP is applied to existing wired network in order to guarantee a QoS of multimedia traffic in mobile computing environment in this paper. If MN moves to another area when Mobile IP is applied to RSVP, HA makes new tunnel to FA because SESSION ID of MN is changed. However, we suggest MIP-DUDN method, which applied RSVP. Although MN moves to another area in this method, it does not make new tunnel because it eliminates the problem of existing Triangle Routing Problem. We design the new protocol of RMIP-DUDN and compare with the method of existing Mobile IP applied to RSVP.

• Human Ecology Research
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• v.58 no.4
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• pp.497-515
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• 2020

The use of mobile payment services has recently increased in South Korea. Mobile payments allow consumers to purchase items digitally, using a mobile card in an app affiliated with a payment service. This study explores the predictors of intention to adopt mobile payment services. The study employed an A(affective)-B(behavioral)-C(cognitive) model with two antecedent variables: cognitive (perceived usefulness, perceived risk, perceived ease of use, and perceived herding behavior) and affective (satisfaction with the status quo, innovation resistance) responses. An online survey of 405 non-users of mobile payment services aged 20 to 49 years was conducted. The study used SPSS 23.0 for descriptive analysis and Amos 23.0 for confirmatory factor analysis and structural equation modelling. The results are as follows. First, perceived usefulness, perceived risk, and perceived herding behavior significantly influenced innovation resistance. Second, perceived herding behavior significantly influenced subjective norms. Third, innovation resistance and subjective norms significantly influenced the intention to adopt mobile payment services. The findings suggest that the A-B-C model can be useful in understanding consumers' adoption and resistance behaviors and that cognitive and affective responses are important antecedent variables affecting the decision to adopt mobile payment services.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.3
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• pp.208-220
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• 2006

Energy of wheeled mobile robot is usually supplied by batteries. In order to extend operation time of mobile robots, it is necessary to minimize the energy consumption. The energy is dissipated mostly in the motors, which strongly depends on the velocity profile. This paper investigates various 3-step (acceleration - cruise - deceleration) speed control methods to minimize a new energy object function which considers the practical energy consumption dissipated in motors related to motor control input, velocity profile, and motor dynamics. We performed an analysis on the energy consumption various velocity profile patterns generated by standard control input such as step input, ramp input, parabolic input, and exponential input. Based on these standard control inputs, we analyzed the six 3-step velocity profile patterns: E-C-E, P-C-P, R-C-R, S-C-S, R-C-S, and S-C-R (S means a step control input, R means a ramp control input, P means a parabolic control input, and E means an exponential control input, C means a constant cruise velocity), and suggested an efficient iterative search algorithm with binary search which can find the numerical solution quickly. We performed various computer simulations to show the performance of the energy-optimal 3-step speed control in comparison with a conventional 3-step speed control with a reasonable constant acceleration as a benchmark. Simulation results show that the E-C-E is the most energy efficient 3-step velocity profile pattern, which enables wheeled mobile robot to extend working time up to 50%.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.230-232
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• 2013

본 논문에서는 실내 음영지역에서 사용되는 모바일 와이맥스의 펨토셀 기지국(WFAP; WiMAX Femtocell AP)에 대한 성능을 분석하였다. 시뮬레이션을 통해 와이맥스 펨토셀 기지국의 패킷에러율(PER), Outage, throughput을 확인하였다.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.725-730
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• 2009

Recently, there has been increasing interest to web access through mobile host due to the explosion of internet mobile terminal such as smart phone. However, small displays of mobile hosts make it difficult to browse the full content of a web page at a time. In order to overcome these limitation, we have designed and implemented Web-based text summarization system. The proposed system can summarize the text for the Web page in which abundant text exist in a page. This can reduce the amount of data transmission and minimize the unnecessary data output during browsing at mobile host. Through implementation, we have confirmed the functions of the proposed system.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.2
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• pp.74-80
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• 2000

In this paper, we present a control method of mobile power assist systems. Most of mobile power assist systems have a heavy base for preventing easy tumbling, so continual movement of the base during operations causes high energy consumption and gives the high risk of human injury. Furthermore, the slow dynamics of the base limits the frequency bandwidth of the whole system. Thus we propose a cooperation control method of the mobile base and manipulator, which removes the unnecessary movements of the base. In our scheme, the mobile base does not move until the center of gravity(C.G) of the system goes outside a safety region. When C.G. reaches the boundary of the safety region, the base starts moving to recover the manipulator's initial configuration. By varying the parameters of a human impedance controller, the operator is warned by a force feedback that C.G. is on the marginal safety region. Our scheme is implemented by assigning a nonlinear mass-damper-spring impedance to the tip of the manipulator. Our scheme is implemented by a nonlinear mass-spring impedance to the tip of the manipulator. The experimental results show the efficacy of the proposed control method.