• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.1
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• pp.1-9
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• 2018

In this paper, we propose a film-type dual-band frequency selective structure for improving the wireless communication environment in a building. The proposed frequency-selective structure is a miniaturized structure that can control the resonant frequencies of 2.4 GHz and 5 GHz dual band through simple design parameters. We fabricated the frequency-selective surface by screen printing using conductive ink on a thin transparent film and confirmed its performance by measurement. We analyzed the attenuation performance of the unnecessary signal from the outside when the frequency-selective structure designed using the software to analyze the propagation environment performance is applied to the building. To verify the analytical results, the signal strength of the indoor environment was measured by applying the frequency-selective film fabricated on the inner wall of the actual building. The measurement results show that the dual-band frequency-selective film has 29.4 dB and 15.94 dB attenuation performance in the 2.4 GHz and 5 GHz, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.640-651
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• 2016

We propose an effective ToA-based localization method considering accuracy in indoor environments. The purpose of the localization system is to estimate the coordinates of the geographic location of target device. In indoor environments, accurately estimating the location of a target device is not easy due to various errors. The accuracy of wireless localization is influenced by NLOS errors. ToA-based localization measures the location of a target device using the distances between a mobile device and three or more base stations. However, each of the NLOS errors along a distance estimated from a target device to a base station is different because of dissimilar obstacles. To accurately estimate the target's location, an optimized localization process is needed in indoor environments. In this paper, effective ToA-based localization method process is proposed for improving accuracy in wireless sensor networks. Performance evaluations are presented, and the experimental localization system results are proved through comparisons of various localization methods with the proposed methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.177-181
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• 2002

본 논문에서는 FCC에서 제정한 허용 주파수 3.1-10.6GHz 대역 내에서 사용 가능한 모노펄스를 이용하여 PPM 변조된 TH IR 시스템 시뮬레이터를 설계하고 시뮬레이터를 이용하여 모노사이클 펄스 특성 및 시스템 성능을 분석하였다. 또한, 제안한 파라미터를 이용하여 다원접속 간섭 환경에서 IR 시스템의 오율 성능을 분석하였다.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.9
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• pp.369-376
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• 2017

Recently, an RSSI-based fingerprinting localization technology has been widely used in indoor location-based services. In the conventional fingerprinting method, as many APs as possible are used to increase the accuracy of location estimation. In another study, a part of APs having the strongest RSSI signal intensity are selected and used to reduce the time spent for positioning. However, it does not reflect the influence of RSSI occurred from the changes of the surrounding environments such as human movement or moving obstacles in a real environment. The environmental changes may cause the difference between the predicted RSSI signal strength value and the measured value, and thus occur an unpredictable error in the position estimation. Therefore, in order to mitigate the error caused by environmental factors, it is necessary to select APs suitable for indoor positioning estimation considering the changes in the surrounding environments. In this paper, we propose a method to select stable APs considering the influence of surrounding environments and derive a suitable positioning algorithm. In addition, we compare and analyze the performance of the proposed method with that of the existing AP selection methods through experiments.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.05a
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• pp.344-345
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• 2018

본 논문에서는 오디오와 레이더 기반의 딥러닝을 활용한 환경 분류 기술을 제안한다. 제안된 환경 분류 기술은 오디오를 이용한 환경 분류 딥러닝 모델과 레이더를 이용한 딥러닝 모델을 앙상블로 결합하여 환경을 분류한다. 특히, 오디오와 레이더 각 성능을 높이기 위해 별도의 모델이 제안된 딥러닝 환경분류 기법은 실내 환경 5 가지를 분류 하였으며, 오디오 또는 레이더 단일 데이터를 활용한 환경 분류에 비해 우수한 성능을 보였다.

• Journal of Bio-Environment Control
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• v.10 no.1
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• pp.42-49
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• 2001

This study was carried out to develop a fuzzy control technique of ventilation window for controlling a temperature in a greenhouse. To reduce the fuzzy variables, the inside air temperature shop was taken as one of fuzzy variables, because the inside air temperature variation of a greenhouse by ventilation at the same window aperture is affected by difference between inside and outside air temperature, outside wind speed and the wind direction. Therefore, the antecedent variables for fuzzy algorithm were used the control error and its slop, which was same value as the inside air temperature slop during the control period, and the conclusion variable was used the window aperture opening rate. Through the basic and applicative control experiment with the control period of 3 minutes the optimum ranges of fuzzy variables were decided. The control error and its slop were taken as 3 and 1.5 times compared with target error in steady state, and the window opening rate were taken as 30% of full size of the window aperture. To evaluate the developed fuzzy algorithm in which the optimized 19 rules of fuzzy production were used, the performances of fuzzy control and PID control were compared. The temperature control errors by the fuzzy control and PID control were lower than 1.3$^{\circ}C$ and 2.2$^{\circ}C$ respectively. The accumulated operating size of the window, the number of operating and the number of inverse operating for the fuzzy control were 0.4 times, 0.5 times and 0.3 times of those compared with the PID control. Therefore, the fuzzy control can operating the window more smooth and reduce the operating energy by 1/2 times of PID control.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.715-721
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• 2008

공동주택에서의 음환경 성능은 실내환경의 질과 연관시켜 설계단계부터 충분한 검토가 필요한 성능항목이다. '국토해양부'는 '공통주택 성능등급 표시제도'에서 Air Duct를 통해 상하층간 전파되는 소음을 제어하기 위한 대책을 요구하고 있다. 이에 화장실에 적합한 구조 및 재질로 소음 저감기를 개발하고, 소음기 성능평가 장치를 구성하여 이론과 비교평가하고, 실제 현장에 설치 시 적용효과를 분석하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.606-610
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• 2003

본 논문에서는 임펄스 잡음과 실내 무선 페이딩, 그리고 다중 사용자 간섭 환경에서 멀티코드 DS/CDMA-BPSK 통신 시스템의 BER 성능을 분석하였다. 분석 결과 멀티코드의 수가 증가함에 따라서 하나의 사용자에게 점유되는 채널의 수가 증가하여 시스템의 성능은 열화 되나 반면에 시스템에서 제공할 수 있는 서비스의 속도는 멀티코드의 수에 비례하여 증가함을 알 수 있었다. 또한, 성능개선기법으로 Turbo Code와 다이버시티 기법을 적용함으로써 전력선에서 방출되는 임펄스 잡음 파라미터인 A=0.2, $\Gamma$' =0.22에서 전송속도에 따라 5.5, 7, 16dB의 신호전력 이상에서 $10^{-5}$ 이하의 BER 성능을 얻을 수 있었다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.257-258
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• 2003

사회가 고도로 발달하면서 현대인의 생활공간은 대부분 사무실이나 가정에서 보내는 시간이 하루의 80-90% 이상을 차지하므로 오히려 실외공기보다 실내환경의 공기오염이 수백 배 높은 실정이다1). 대부분의 시간을 특정공간에서 보내게 되므로 현대인의 건강과 편리함을 위해 실내공간에 설치되는 탈취제품(공기 청정기)이 많이 상품화 되고 있다. 본 연구에서는 암모니아(NH$_3$), 트리메틸아민(($CH_3$)$_3$N), 초산($CH_3$COOH), 황화수소(H$_2$S), 메칠멀켑탄($CH_3$SH), 황화메틸 ($CH_3$S$CH_3$), 이황화메틸($CH_3$SS$CH_3$), 아세트알데히드($CH_3$CHO), styrene(C$_{8}$H$_{8}$)등 9종의 악취물질을 대상으로 탈취제품의 객관적인 탈취 능력 평가를 위한 시험방법을 개발하고자 하였다.(중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6C
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• pp.506-515
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• 2010

In this paper, we compare and analyze the spectral efficiency of representative adaptive MIMO algorithms in indoor environments. We first briefly investigate the modulation and demodulation schemes of MIMO algorithms to be compared and then implement adaptive algorithms by using BPSK and square QAM schemes up to 256QAM. We finally compare the spectral efficiency of adaptive MIMO algorithms employing (2$\times$2) or (4$\times$4) antenna array through the computer simulation in indoor environments.