• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.687-689
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• 2010

In this paper, the equalization for frequency slope of path loss in Multi-Band(MB) OFDM UWB is proposed. The path loss of a signal is proportionate to the square of the signal's frequency. So, the received signal amplitudes of OFDM subcarrier can be different up to 3dB when MB-OFDM occupies bandwidth over 1.5GHz. The differences of subcarrier-amplitudes make an effective of 0.3 bit reduction of soft decision bits of viterbi decoder, and when the effective of 0.3 bit reduction can cause 0.5dB SNR degradation. This paper proposes two modem architectures which compensate for the degraded subcarrier by multiplying the reciprocal of degraded values in analog or digital domain. It is shown that, for the proposed architecture applied to MB-OFDM UWB, the performance improvements up to 0.5dB can be obtained over the conventional uncompensated receiver architecture.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.836-841
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• 2008

Ubiquitous computing represents the most explicit attempt yet to move computing technology beyond the confines of tool usage towards a pervasive penetration of everyday life. In this report, as a general introduction of Ubiquitous computing, a trend of Ubiquitous computing devices is proposed for the applied technology fields and our everyday life. We outline a broad analysis of this technology based on a close examination of the researches advancing it. After introducing a framework for understanding modem device technology, we develop an interpretation of ubiquitous computing concentrating on its guiding principles, technological infrastructure, and trends.

• Journal of Power Electronics
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• v.9 no.2
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• pp.207-214
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• 2009

This paper presents a modem approach for speed control of a PMSM using the Particle Swarm Optimization (PSO) algorithm to optimize the parameters of the PI-Controller. The overall system simulated under various operating conditions and an experimental setup is prepared. The use of PSO as an optimization algorithm makes the drive robust, with faster dynamic response, higher accuracy and insensitive to load variation. Comparison between different controllers is achieved, using a PI controller which is tuned by two methods, firstly manually and secondly using the PSO technique. The system is tested under variable operating conditions. Implementation of the experimental setup is done. The simulation results show good dynamic response with fast recovery time and good agreement with experimental controller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9B
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• pp.1314-1320
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• 2001

최근 전화선과 같이 기존에 존재하는 전송선로를 이용하여 고속의 데이터를 전송할 수 있는 DSL 모뎀 개발에 많은 연구가 활발히 진행되고 있다. DSL 모뎀과 같이 열악한 특성과 제한된 대역폭을 갖는 채널을 통하여 고속의 데이터를 전송하기 위해서는 복잡한 변조방식과 우수한 채널부호(FEC) 알고리즘이 요구된다. 특히, ADSL 시스템 및 VDSL 시스템에서는 다양한 오류정정 능력을 갖는 RS(Reed-Solomon) 부호를 사용하도록 권고하고 있다. 이에 대해, 본 논문에서는 ADSL 및 VDSL 시스템의 권고 안(오류정정 능력(t) = 0∼8)을 만족하는 RS 부호를 한 조의 RS 부호기 및 복호기로 대체할 수 있는 설계구조를 제시한다. 제시된 구조는 8조의 RS 부호가 갖는 면적의 약 23%만으로, t=8인 RS 부호에 대해 약 6%의 추가 면적으로 설계할 수 있다.

• KIEAE Journal
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• v.2 no.4
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• pp.21-26
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• 2002

Modem architecture represent a great capitalistic, polishing, high-technology image to the public by design. As a result, glass architecture which show 'transmittance' in desinging play a leading part, consequently a role of machine is increasing in controlling an internal environment of building. These movement look like assisting an universal standard building disregarding a each nation's climate peculiarity, if glass building is applied by a proper external shading device. the shading device has a great effect on the reduction of cooling load energy, this research to propose the proper designing scheme of the fixed external shading device. The effect of proper external shading device on the cooling load is evaluated by the numeric simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.781-782
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• 2016

본 논문은 스마트그리드 중요 인프라인 AMI 시스템 성능 제고를 위해 다양한 환경에서의 원격검침이 가능한 솔루션 개발에 있어 통신환경 등을 고려하였을 때 다양한 통신기술에 맞춰 원격검침 서비스를 제공할 수 있는 복합 브릿지 모뎀의 개발 사례를 다루고자 한다. 유무선 복합 기술을 적용하기 위해 TVWS 대역 무선 통신, 저속 PLC를 복합적으로 적용하였다. 본 개발 모뎀은 현재 시작품 형태로 제작이 되어 있으며, 현재 진행 중인 연구가 완료되는 시점에는 제품수준의 복합 모뎀이 산출될 예정이다.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.15-18
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• 2002

This paper presents an ECG (electrocardiogram) telemetry system, in which patients can be monitored in nearly any environment by mobile communication. The ECG is transmitted to a monitor center via a built-in CDMA modem and forwarded to a cardiologist for diagnosis. Also this paper designed and implemented the receiving server which receives the ECG from the ECG aquisition module of patients by Internet. The server puts the ECG into a database. This telemetry system significantly increases the patient's safety and comfort.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.670-672
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• 1999

무선 통신과 관련된 기술이 발전함에 따라 산업용 기기나 단순한 제어기들을 위한 무선 모뎀의 활용이 두드러지고 있으나, 기존의 통신 프로토콜들이 여러 측면에서 무선 모뎀에 적합하지 않아 무선 모뎀의 특성을 제대로 활용할 수 없으며 HDLC는 기능이 매우 다양하고 구현하기 어려워 저수준의 기기들에 적합하지 않은 점들이 많다. 본 논문에서는 기존의 통신 프로토콜들을 검토하여 무선 모델의 통신 특성에 적합하고 구현이 용이한 무선 모뎀을 위한 프로토콜을 제안한다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.247-250
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• 2008

최근 무선통신용 LSI는 배터리 수명과 관련하여, 저전력 동작이 중요시되고 있다. 따라서 Digital CMOS 신호처리와 더불어 동작 가능한 SI (Switched-Current) circuit를 이용하는 Current-mode 신호처리가 주목받고 있다. 그러나 SI circuit의 기본인 Current Memory는 Charge Injection에 의한 Clock Feedthrough라는 문제점을 갖고 있기 때문에, 전류 전달에 있어서 오차를 발생시킨다. 본 논문에서는 Current Memory의 문제점인 Clock Feedthrough의 해결방안으로 CMOS Switch의 연결을 검토하였고, 0.25${\mu}m$ CMOS process에서 Memory MOS와 CMOS Switch의 Width의 관계는 simulation 결과를 통하여 확인하였으며, MOS transistor의 관계를 분명히 하여, 설게의 지침을 제공한다.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.6
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• pp.772-782
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• 2005

The purpose of this study was to identify important factors influencing fragrance sensibility responses as well as to explore fragrance sensibility factors affecting attitude toward and buying intention of perfume products. For data collection, smelling experiments were conducted with seven groups of 34 female consumers who are aged from the 20's to 40's. Data were analyzed by ANOVA, t-test, factor analysis, and linear regression analysis. In results, five factors (pleasant, romantic, stimulating, modem, familiar factors) were generated from the factor analysis of 24 fragrance sensibility factors. These fragrance sensibility factors significantly affected both attitude toward and buying intention of perfume products. Pleasant, romantic and familiar factors were considered as important factors affecting attitude and buying intention while the stimulating factor affected only buying intention. Fragrance sensibility factors influencing attitude and buying intention of perfume products differed in terms of age and purchase level of consumers.