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이재일(Jaeil Lee),이종현(Chong Hyun Lee),이승욱(Seung Wook Lee),신정채(Jungchae Shin),정진우(Jin Woo Jung) 대한전자공학회 2012 전자공학회논문지 Vol.49 No.12
본 논문에서는 파라메트릭 배열 기반 소나 통신 성능을 분석하였다. 분석을 위하여 음향학적 설계요소를 고려한 최적의 차 주파수 발생조건을 구하고 비선형성이 고려된 소나 방정식을 이용하여 차 주파수의 SNR을 추정하였다. 추정된 차 주파수의 SNR을 이용하여 디지털 변조 방식에 따른 이론적인 비트오류확률과 MIMO 채널 용량을 모의실험 하였다. 1차 주파수의 평균 주파수를 560kHz, 차 주파수를 45kHz 그리고 방사 파워 28.05Watt를 가정할 때, 비트오류확률10<SUP>-4</SUP>이하의 통신 거리는 1차 주파수를 사용할 경우 0.9km이고 차 주파수는 4.25km로 3.35km의 거리 이득을 얻음을 확인하였다. 또한 요구되는 채널 용량 10bps/Hz를 가정할 때 1차 주파수의 구동거리는 0.83km인 반면 주파수의 경우 SISO 통신은 3.8km 그리고 2x2 MIMO 통신은 3.98km 까지 전송 할 수 있음을 확인 하였다. In this paper, we present novel analysis results of sonar communication using parametric array. We consider transducer diameter, primary frequency, difference frequency and acoustic power as analysis parameters of communication performance. We calculate theoretical BER(Bit Error Rate) and channel capacity of MIMO(Multi Input and Multi Output) communication system. By considering practical parameters, we obtain optimum difference frequency generation condition. The obtained primary frequency is 560 kHz, difference frequency 45kHz and acoustic power is 28.05Watt. For BER of 10<SUP>-4</SUP>, the range gain of parametric array communication is 3.35km compared to primary frequency communication. For channel capacity of 10bps/Hz, the SISO and 2x2 MIMO communication range of parametric array communication are 3.8km and 3.98km respectively, while primary frequency communication range is 0.83km.
천해 배경잡음 환경에 적합한 과도신호의 특징 및 변별력 분석
이재일(Jaeil Lee),강윤정(Youn Joung Kang),이종현(Chong Hyun Lee),이승우(Seung Woo Lee),배진호(Jinho Bae) 대한전자공학회 2014 전자공학회논문지 Vol.51 No.7
본 논문에서는 천해 배경잡음 환경에서 과도신호 분류에 적합한 특징 선택을 위해 특징의 변별력을 분석하였다. 과도신호분류는 해양환경 특성상 낮은 신호대잡음비(SNR)를 가지므로 잡음변화에 강인한 특징이 요구된다. 천해 배경잡음을 모델링하기 위해 이론적인 잡음 모델과 Wenz의 천해 관측 자료 그리고 Yule walker 필터를 이용하였다. 과도신호의 SNR에 따른 각 특징의 변별력은 Fisher score를 이용하여 분석하였다. 변별력이 높은 특징을 선택하여 24 클래스의 과도신호원에 대한 분류정확도를 분석한 결과 잡음이 없는 환경에서 선택된 특징에서 상대적으로 높은 분류정확도를 보였다. 이러한 결과를 토대로 최종적으로 선택된 특징은 전체 28가지 특징 중 16가지 특징이 선택되었다. 다중 클래스 SVM분류기를 이용하여 선택된 특징의 인식률 분석결과 과도신호의 SNR 20dB 환경에서 약92%의 분류정확도를 보였다. In this paper, we analyze the discriminability of features for the classification of transient signals with an ambient noise in a shallow water. For the classification of the transient signals, robust features for the variance of a noise are required due to a low SNR under a marine environment. In the modelling the ambient noise in shallow water, theoretical noise model, Wenz’s observation data from the shallow water, and Yule-walker filter are used. Discrimination of each feature of the transient signals with an additive ambient noise is analyzed by utilizing a Fisher score. As the analysis of a classification accuracy about the transient signals of 24 classes using the selected features with a high discriminability, the features selected in the environment without a noise relatively have a good classification accuracy. From the analyzed results, we finally select a total 16 features out of 28 features. The recognition using the selected features results in the classification accuracy of 92% in SNR 20dB using Multi-class SVM.
PDR 센서의 검출 시간차를 이용한 표적 경로 검출 알고리즘
이재일(Jaeil Lee),이종현(Chong Hyun Lee),배진호(Jinho Bae),권지훈(Jihoon Kwon),전종훈(Jonghoon Chun),이노복(Nobok Lee) 제어로봇시스템학회 2011 제어로봇시스템학회 합동학술대회 논문집 Vol.1 No.1
본 논문에서는 탐지영역에 존재하는 이동 표적 유무 정보만을 제공하는 제한된 PDR(Pulse Doppler Radar 센서노드 환경에서 인접한 한 쌍의 PDR 센서로부터 표적 이동 경로에 따른 검출 시간차의 통계적 특성을 이용한 표적 경로 검출 알고리즘을 제안한다. 알고리즘에 사용된 변수는 실측 실험 정보를 기반으로 도출한 표적 검출 시작 시간차와 비검출 시간차 이다. 또한 한 쌍의 PDR센서 탐지 영역에서 발생되는 표적 이동 경로를 센서를 관통하는 경로, 센서와 병렬로 이동하는 경로 그리고 두 센서 사이를 바라보고 진입한 후 한쪽 센서 방향으로 향하는 3가지 경우로 제한한 후 각각 600회의 실험 결과 각 경우에 따른 오류 검출 백분율은 각각 5.67%, 5.83% 그리고 7.17%이며, 검증 결과 제한된 표적 검출 환경에서 높은 검출 확률을 얻었다.
이재일(Jaeil Lee),배진호(Jinho Bae),이종현(Chong Hyun Lee),팽동국(Dong-Guk Paeng),이동식(Dongsik Lee),전종훈(Jonghoon Chun),이노복(Nobok Lee) 제어로봇시스템학회 2011 제어로봇시스템학회 합동학술대회 논문집 Vol.1 No.1
We propose an algorithm to find the footstep classification of person movement using seismic sensor. A field study were conducted in 2011 at Jeju national university, to document seismic signature of a person who is walking crawling and running in ground. The person generated a vertical ground vibration were recorded using 2000 Hz of sampling frequency with geophone (GD20DX). The hypothetical sensor performance predictions were made using a s statistical signal processing approach is developed footstep classification of the movement of a person. We experimentally verified the algorithm of the footstep classification by using the collected seismic data.
Lee, Jaeil The Costume Culture Association 2002 Fashion, industry and education Vol.5 No.3
The main focus of this study is to understand realities of postmodern consumer culture by deconstructing fashion advertisements, Calvin Klein's ck One and cK be. The metaphysics of critical theory, visual and textual analysis are used to deconstructing the ads applying one of the postmodern cultural critics, Baudrillard' s notion of hyperreality. Through deconstructing the ads five postmodern characteristics representing hyperreality were found. First, there is no message regarding functional characteristics of the product offered in the ad, which is far from the modernist's utilitarian Point of view. Hyperreality in Postmodern consumer culture is consumption centered and focuses on the product's symbolic meanings. Second, especially for cK be, the ad uses atypicai, irrelevant models and images, which are introduced as a concept of ‘real people’ rather than the ideal person or body type. Third, there are transformations of the meanings from cK one to cK be such as the notions of globalization and gender which clearly represent ongoing reality in the Postmodern culture. Fourth, there are hidden meaning of hedonism and relativism, which are prevalent in postmodern ideology. Finally, models' bodies are used to convey messages as well as form the ground and figure in the ad that is a significant characteristic of postmodern consumer culture. In conclusion, the study of Calvin Klein's fashion ads supports the notion that advertising mirrors reality in postmodern consumer culture, which is hyperreality.
Characterization of Thin Liquid Films Using Molecular Dynamics Simulation
Jaeil Lee,Seungho Park,Ohmyoung Kwon,Young Ki Choi,Joon Sik Lee 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.11
Various characteristics of a thin liquid film in its vapor-phase are investigated using the molecular dynamics technique. Local distributions of the temperature, density, normal and tangential pressure components, and stress are calculated for various film thicknesses and temperature levels. Distributions of local stresses change considerably with respect to film thicknesses, and interfacial regions on both sides of the film start to overlap with each other as the film becomes thinner. Integration of the local stresses, i.e., the surface tension, however, does not vary much regardless of the interfacial overlap. The minimum thickness of a liquid film before rupturing is estimated with respect to the calculation domain sizes and is compared with a simple theoretical relation.<br/>
Simulation and Design of a Multilayer Piezoelectric Actuator
Lee, Kabsoo,Yoo, Juhyun,Lee, Sangho,Hong, Jaeil The Korean Institute of Electrical and Electronic 2017 Transactions on Electrical and Electronic Material Vol.18 No.3
In this study, two- and three-layer ceramic piezoelectric actuators were designed and simulated according to SUS316 thickness, actuator width, and mass using ATILA software in order to develop a piezoelectric actuator for haptic application. Numerical modelling based on the finite element method was performed to find the resonance frequencies and modal shapes of the actuator. The resonance frequency was affected by the thickness of the SUS316 plate and mass. On the other hand, the width of the actuator did not have a significant impact. Maximum displacements were generated at the center of a haptic three-layer ceramic piezoelectric actuator. The two-layer ceramic piezoelectric actuator with a mass of 2.6 g was suitable as $16.28{\mu}m$ at 265 Hz for haptic sensation application.