• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.71-72
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• 2012

NFC(Near Field Communication)는 13.56Mhz를 사용하는 근거리 무선통신으로 PC, 휴대폰 등의 전자 기기간 양방향 데이터를 송수신할 수 있는 기술이다 [1]. 안드로이드를 중심으로 채택되기 시작한 NFC 기술은 스마트폰과의 연결을 통하여 새로운 다양한 비즈니스 모델을 만들어 내고 있다. 본 논문에서는 이러한 NFC기술을 대형 마트 도메인에 적용하여 마트를 방문하는 고객이 편리하고 빠르게 장을 볼 수 있도록 도와주는 애플리케이션 개발내용에 대해 기술한다. 본 애플리케이션을 이용하여 고객은 장보기 전에 구입할 상품을 장바구니에 미리 등록할 수 있으며 예산금액을 설정할 수 있다. 고객이 마트를 방문 시 출입구에 부착되어있는 NFC 태그를 인식하여 장바구니에 등록한 상품에 관한 맞춤형 정보를 얻을 수 있고 마트 진열대의 상품에 장착된 NFC 태그를 스마트 폰으로 인식하여 장바구니에 등록된 상품과 체크하며 장보기를 실시한다. 장보기 완료 후에는 포스기에서 NFC 태그를 인식하고 결제방법을 선택하고 결제를 한다. 결제 후 상품은 포장단계에 적용되고 포장이 완료된 후 배송하게 된다. 대형마트에서는 본 시스템을 갖춤으로써 고객들이 좀 더 편리하게 쇼핑할 수 있도록 도와줄 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.645-652
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• 2001

In this paper is adopted the One-Ray Rician channel model for AVHS's platoon to short-range IVC (Inter-Vehicle Communication System) and analyzed packet probability characteristics in 60㎓ millimeter wave with very powerful to MP(multipath-wave). Both Convolution coding and MRC diversity is adopted that Multimedia service is satisfied following user's desire increase in the next and analyzed packet probability characteristics of DS-CDMA/QPSK systems.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.32-41
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• 1999

In this paper, an inversion method using chirp signals and two near field receivers is proposed. Inversion problems can be formulated into the probabilistic models composed of signals, a forward model and noise. Forward model to simulate chirp signals is chosen to be the source-wavelet-convolution planewave modeling method. The solution of the inversion problem is defined by a posteriori pdf. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the ranges for a priori uniform distribution is based. The genetic algorithm can be applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L₂norm of the difference between measured and modeled signals. The observed signals can be separated into a set of two signals reflected from the upper and lower boundaries of a sediment. The separation of signals and successive applications of the genetic algorithm optimization process reduce the search space, therefore improving the inversion results. Not only the marginal pdf but also the statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. The examples applied here show that, for synthetic data with noise, it is possible to carry out an inversion for sedimentary layers using the proposed inversion method.

• Journal of Convergence Society for SMB
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• v.5 no.2
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• pp.21-26
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• 2015

Recently, NFC technology of short-range wireless communication using a smart phone to perform personal authentication with the electronic payment has been in the spotlight in various fields. However, the security associated with the personal information and the location information is vulnerable because it is easily fused with the existing mobile services and devices. In this paper, we propose a model for NFC payments help protect personal information and location information of NFC payment systems and services in various fields. Proposed model uses tag-based services in order to protect personal information and position information. The proposed model using the tag-based services is the place to check the various features available information in a simple Tag that can be easily accessed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.111-119
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• 2010

With the rapid progress of wireless technologies today, mobile terminals with multiple access interfaces are emerging. In recent years, WLAN (Wireless Local Area Networks) has become the premier choice for many homes and enterprises. WiMAX (Worldwide Interoperability for Microwave Access) has also emerged as the wireless standard that aims to deliver data over long distances. Therefore, it is important to explore efficient integration methods for delivering multimedia data between heterogeneous wireless networks. In this paper, we developed the simulation models and environments for the mobile multihomed node that has both WiMAX and WLAN interfaces and can move around in both networks by using mobile IP. In order to verify the developed models, we designed and constructed several simulation scenarios, e.g. movement in WiMAX/WLAN, group mobility, MANET, and nested MIP under the various traffic environments such as oneway or bothway UDP packets, FTP traffic, and voice with SIP protocol. The simulation results show that the developed models are useful for mobility studies in various integrated wireless networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1284-1294
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• 2010

The ZigBee is one of the most important technologies for composing USN. It is one of the IEEE 802.15.4 standards to support personal area networks. It uses a hierarchical routing or an on-demand route discovery strategy as an address allocation method. A hierarchical routing doesn't use a routing table but only uses a child node or a parent node as an intermediate node for data delivery. Therefore, the ZigBee network's topology greatly affects the overall network performance. In this paper, we propose a more trustworthy algorithm than only using the depth and widely variable LQI during network formation, and moreover we propose an algorithm to measure network's trustworthiness. We simulate our algorithm using the NS-2 and implement our network using the MG2400 ZigBee module for verifying performance.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.360-365
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• 2008

We propose an efficient robot name registration and recognition method in order to enable a Call-and-Come service for home robots. In the proposed method for the name registration, the search space is first restricted by using monophone-based acoustic models. Second, the registration of robot names is completed by using triphone-based acoustic models in the restricted search space. Next, the parameter for the utterance verification is calculated to reduce the acceptance rate of false calls. In addition, acoustic models are adapted by using a distance speech database to improve the performance of distance speech recognition, Moreover, the location of a user is estimated by using a microphone array. The experimental result on the registration and recognition of robot names shows that the word accuracy of speech recognition is 98.3%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.87-94
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• 1990

In this study, the block adjustments are perfomed by bundle adjustment method of analytical photogrammetry, and the characteristics of 3-dimensional errors for the objects are analysed. The optimal arrangement and configuration of the control points is selected from various arrangements and configurations of control points, and the accuracies of result obtained by block adjustment and by single model adjustment are compared, And the accuracy of bundle block adjustment is compared with that of the independent model triangulation which is another method in block adjustment with additional parameters by selecting the suitable systematic error model. As a result of this study, an the effective method to improve accuracy in close-range photogrammetry was presented by forming blocks and using bundle block adjustment with proper arrangement and configuration of control poinst.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.807-810
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• 2007

Recently, ultra-wideband (UWB) technology based on the transmission of short duration pulses has gained much interest for its application to wireless communications. UWB small scale channel modeling work, including statistical characterization and potential models, are discussed. The significance, in terms of performance, of the channel impulse response model chosen for the simulation of UWB communications systems is also evaluated. Three traditional models are found to be useful for modeling NLOS UWB channels, but not LOS channels. In this paper, a new model for LOS UWB channels is presented and shown to represent LOS channels much more accurately than the traditional models.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.55-59
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• 2016

Conventional RF energy harvesting systems can harvest energy and decode information from same source as an Hybirid-AP (H-AP). However, harvesting efficiency is seriously dependent on distance between users and H-AP. Therefore, in this paper, we proposed a transmission model for RF harvesting consisting of information and power source separately called Decoupled RF Energy harvesting networks. Main purpose of this paper is to maximize energy efficiency under various constraints of transmit power from H-AP and power beacon (PB), minimum quality of service and quality of harvested power of each users. To measure proposed model's performance, we proposed optimal time scheduling algorithms for energy efficiency (EE) maximization using Lagrangian dual decomposition theory that locally maximizes the EE by obtaining suboptimal values of three arguments : transmit power of H-AP, transmit power of PB, frame splitting factor. Experiment results show that the proposed energy-efficient algorithms converge within a few iterations with its optimality and greatly improve the EE compared to that of baseline schemes.