• Journal of information and communication convergence engineering
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• 제13권4호
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• pp.235-240
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• 2015

A decimation chain for multi-standard reconfigurable radios is presented for 900-MHz and 1,900-MHz dual-band cellular standards with a data interpolator based on the Lagrange method for adjusting the variable data rate to a fixed data rate appropriate for each standard. The two proposed configurations are analyzed and compared to provide insight into aliasing and the signal bandwidth by means of a newly introduced measure called interpolation error. The average interpolation error is reduced as the ratio of the sampling frequency to the signal BW is increased. The decimation chain and the multi-rate analog-to-digital converter are simulated to compute the interpolation error and the output signal-to-noise ratio. Further, a method to operate the above-mentioned chain under a compressed mode of operation is proposed in order to guarantee continuous packet connectivity for inter-radio-access technologies. The presented decimation chain can be applied to LTE, WCDMA, GSM multi-mode multi-band digital front-end which will ultimately lead to the software-defined radio.

• 대한의용생체공학회:의공학회지
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• 제27권4호
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• pp.170-179
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• 2006

The purpose of this study was to investigate the spatiotemporal cortical activation pattern and functional connectivity during visual perception of words. 61 channel recordings of electroencephalogram were obtained from 15 subjects while they were judging the meaning of Korean, English, and Chinese words with concrete meanings. We examined event-related potentials (ERP) and applied independent component analysis (ICA) to find and separate simultaneously activated neural sources. Spectral analysis was also performed to investigate the gamma-band activity (GBA, 30-50 Hz) which is known to reflect feature binding. Five significant ERP components were identified and left hemispheric dominance was observed for most sites. Meaningful differences of amplitudes and latencies among languages were observed. It seemed that familiarity with each language and orthographic characteristics affected the characteristics of ERP components. ICA helped confirm several prominent sources corresponding to some ERP components. The results of spectral and time-frequency analyses showed distinct GBAs at prefrontal, frontal, and temporal sites. The GBAs at prefrontal and temporal sites were significantly correlated with the LPC amplitude and response time. The differences in spatiotemporal patterns of GBA among languages were not prominent compared to the inter-individual differences. The gamma-band coherence revealed short-range connectivity within frontal region and long-range connectivity between frontal, posterior, and temporal sites.

• 한국산학기술학회논문지
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• 제10권6호
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• pp.1170-1174
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• 2009

본 논문에서는 현재 모바일용 무선통신 서비스로 사용하고 있으며, 주파수 가변이 가능한 셀룰러(cellular) 대역용 안테나와 커낵티비티 (connectivity) 대역용 안테나를 소형 모바일 기기에 사용하기 위해 제한된 공간 (40mm ${\times}$ 20mm ${\times}$ 6mm) 내에서 설계, 제작, 측정한 결과를 소개 하였다. 각 각의 안테나는 안테나 상에 삽입되어 있는 PIN 다이오드를 이용하여 주파수를 재구성 할 수 있다. 첫 번째 셀룰러 대역용 안테나는 현재 사용되는 셀룰러 대역; 0.82GHz ${\sim}$ 0.96GHz 대역 (GSM/ CDMA) 과 1.7GHz ${\sim}$ 2.17GHz 대역 (DCS/ PCS/ WCDMA) 간의 주파수를 가변할 수 있으며, 두 번째 커낵티비티 대역용 안테나는 현재 사용되는 커낵티비티 대역 3.4GHz ${\sim}$ 3.6GHz 대역 (mWiMax) 와 2.3GHz ${\sim}$ 2.5GHz, 5.15GHz ${\sim}$ 5.35GHz 대역 (WiBro/ WLAN 11a/b/g/n) 간의 주파수를 가변 할 수 있다. 이로써 이종 서비스 (셀룰러/ 커낵티비티)의 안테나를 소형 모바일 기기의 제한된 사이즈의 단일 안테나로 구현하였으며, 주파수 재구성 설계를 통해 안테나의 방사 효율을 향상시키며, 또한 이종서비스 각각의 포트를 분리 설계하여 동시동작 모드로 사용할 수 있다.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2615-2618
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• 2009

본 논문에서는 WLAN 11 a/b/g 대역(2.4 GHz/5.5 GHz)용 4개의 브릿지(bridge)를 가진 이중 사각 패치(double rectangular patch) 안테나를 소개 하였다. 5.5 GHz 주파수 대역용 평면형 사각 패치는 이중 대역동작을 위해 2.4 GHz에서 동작하는 외부 사각 패치와 4개의 인덕티브 브릿지(inductive bridge)를 통해 연결되어 있다. 제안된 안테나는 4개의 인덕티브 브릿지의 넓이를 가변 하여 사용 주파수 대역을 튜닝 할 수 있으며, 안테나의 최대 이득은 5.5 GHz 주파수 대역에서 3.7 dBi 이고 2.4 GHz 주파수 대역에서는 5 dBi이다.

• Smart Structures and Systems
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• 제4권5호
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• pp.565-582
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• 2008

This paper presents a feasibility study of flexible piezoelectric paint for use in wide-band low-profile surface-mount or embeddable ultrasonic sensor for in situ structural health monitoring. Piezoelectric paint is a piezoelectric composite with 0-3 connectivity. Because of its ease of application, piezoelectric paint can be readily fabricated into sensing element with complex pattern. This study examines the characteristics of piezoelectric paint in acoustic emission signal and ultrasonic guided wave sensing. A series of ultrasonic tests including pitch catch and pencil break tests were performed to validate the ultrasonic wave sensing capability of piezoelectric paint. The results of finite element simulation of ultrasonic wave propagation, and acoustic emission generated by a pencil lead break on an aluminum plate are also presented in this paper along with corresponding experimental data. Based on the preliminary experimental results, the piezoelectric paint appears to offer a promising sensing material for use in real-time monitoring of crack initiation and propagation in both metallic and composite structures.

• Journal of Communications and Networks
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• 제6권2호
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• pp.163-172
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• 2004

Ultra Wide Bandwidth (UWB) spread-spectrum techniques will playa key role in short range wireless connectivity supporting high bit rates availability and low power consumption. UWB can be used in the design of wireless local and personal area networks providing advanced integrated multimedia services to nomadic users within hot-spot areas. Thus the assessment of the possible interference caused by UWB devices on already existing narrowband and wideband systems is fundamental to ensure nonconflicting coexistence and, therefore, to guarantee acceptance of UWB technology worldwide. In this paper, we study the coexistence issues between an indoor UWB-based system (hot-spot) and outdoor point to point (PP) links and Fixed Wireless Access (FWA) systems operating in the 3.5 - 5.0 GHz frequency range. We consider a realistic UWB master/slave system architecture and we show through computer simulation, that in all practical cases UWB system can coexist with PP and FWA without causing any dangerous interference.

• 한국인터넷방송통신학회논문지
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• 제11권5호
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• pp.1-9
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• 2011

오늘날에는 모바일 스마트 기기를 많이 사용해본 소비자들이 무선 연결 방식과 같은 보다 편리하고 스마트한 가정용 전자기기의 연결성을 기대하고 있기 때문에 기존의 전기선을 다른 지능적인 연결방법으로 대체하는 것이 필요하다. 이 연구에서는 양방향 CEC 제어 구조를 새롭게 제안하여 밀리미터 밴드 이미지 전송 시스템에서 제어능력을 단방향에서 양방향으로 확장하는 것을 목적으로 하는데, 이는 2자유도 제어 능력이 HDMI 인터페이스 시스템에서 보다 지능적인 편리성을 제공하기 때문이다. 실험연구를 통해 1080p 풀 HD 이미지 스트림에 대해서 3.0 Gbps의 전송 성능 결과를 보여 지능적 2 DOF CEC 인터페이스를 보유한 밀리미터 밴드의 진보된 이미지 전송 솔루션으로서 제안된 시스템의 유용성을 보인다.

• 교육시설 논문지
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• 제21권1호
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• pp.23-32
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• 2014

Aim of this research is suggesting a satisfied studying space for lecturer, student and curriculum by abstraction of improvement plan which based on investigation and analysis of the space that teacher is using in lecturer and study support facility in school which managed in 'Department system'. This research focused on analyse of teacher's laboratory, teacher's room, and common room in middle and high school which managed and designed by 'Department system' and registered on 'Seoul office of education' and designed in management of department system between 2009 and 2012. With these process, a conclusion of this research is as in the following. Firstly, plan of teachers' private place which is efficient and stable is required through to get out of module which can cover subject band and grade band. Secondly, we have to focus on size of teachers' convenience facilities for convenience or official usage, movement radius, and improvement of working environments. Thirdly, 'Subject type teachers' laboratory' which organized by teachers who teach same subject is more efficient than 'Task type laboratory' which organized by teachers who working on same task for management of school. In fourth, 'Task type teachers' laboratory' arranged regardless with teachers' class room to teach, and it makes lack of connectivity between teacher and class room.

• 대한의용생체공학회:의공학회지
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• 제39권3호
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• pp.124-133
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• 2018

We tried to investigate the changes in cortical activities according to emotional valence states during watching video clips. We examined the neural basis of two emotional states (positive and negative) using spectral power analysis and brain functional connectivity analysis of cortical current density time-series reconstructed from high-density electroencephalograms (EEGs). Fifteen healthy participants viewed a series of thirty-two 2 min emotional video clips. Sixty-four channel EEGs were recorded. Distributed cortical sources were reconstructed using weighted minimum norm estimation. The temporal and spatial characteristics of spectral source powers showing significant differences between positive and negative emotion were examined. Also, correlations between gamma-band activities and affective valence ratings were determined. We observed the changes of cortical current density time-series according to emotional states modulated by video clip. Gamma-band activities showed significant difference between emotional states for thirty seconds at the middle and the latter half of the video clip, mainly in prefrontal area. It was also significantly anti-correlated with the self-ratings of emotional valence. In addition, the gamma-band activities in frontal and temporal areas were strongly phase-synchronized, more strongly for negative emotional states. Cortical activities in frontal and temporal areas showed high spectral power and inter-regional phase synchronization in gamma-band during negative emotional states. It is inferred that the higher amygdala activation induced by negative stimuli resulted in strong emotional effects and caused strong local and global synchronization of neural activities in gamma-band in frontal and temporal areas.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.183-186
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• 2005

WUSB is a new technology which combines the speed and the security of wired USB with the easy use of wireless technology. In this paper, GUI for WUSB is designed and implemented to show the connectivity and contents of the WUSB devices. Also, the proposed GUI shows the log window while content transfers occur between the host and device. The proposed GUI can be used for various wireless technologies which provide wireless function with existing USB hosts and devices.