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스마트 빌딩을 위한 가시광 통신 시스템의 성능 향상 기법
서성일,Seo, Sung-Il 한국인터넷방송통신학회 2020 한국인터넷방송통신학회 논문지 Vol.20 No.5
본 논문은 스마트 빌딩을 위한 가시광 통신 시스템 (VLC, Visible Light Communication)에서 통신의 안정성 및 데이터의 신뢰성을 향상시키는 다중 채널 간섭 제거 알고리즘에 대해 연구하였다. 가시광 통신 시스템은 LED (Light Emitting Diode)를 통해 방사되는 가시광을 이용한 차세대 통신 시스템으로 스마트 빌딩을 위한 유비쿼터스 네트워크 서비스 환경에서 에너지 절감 효과를 가져 올 수 있다. 또한 기존 인프라를 활용하여 고출력 전송이 가능하며 유지 보수비용을 절감할 수 있다. 실내에서 다수의 사용자가 통신을 할 경우, 채널 간섭으로 인해 성능의 열화가 발생하게 된다. 간섭 제거를 위해 먼저 MMSE (Minimum Mean Square Error) 기법을 통해 간섭을 제거한 후, 순차 연속 간섭 제거(SIC, Successive Interference Cancellation) 알고리즘을 이용하여 추가적으로 주변의 영향력이 큰 간섭원을 제거하여 성능을 향상시켰다. 채널 모델로서 실내 가시광 통신 모델을 적용 하였고, 비트 오류율 (BER, Bit Error Rate)을 평가하여 성능을 검증하였다. 모의실험을 통해 제안된 시스템의 성능을 검증하였고 기존의 시스템보다 향상된 결과가 나타냈다. 제안한 시스템 모델은 가시광 통신뿐만 아니라 일반적인 통신 시스템에서도 신호의 품질을 향상시킬 수 있도록 다양하게 적용이 가능하다. In this paper, we propose the multi-channel interference cancellation algorithm for visible light communication (VLC) in smart building. The VLC system is communication technology using visible rays that come out in Light Emitting Diode (LED) device. It has energy curtailment effect and possible to use in ubiquitous network service applications. When a large number of users communicate indoors, the performance can be reduced due to channel interference. To remove interference, at the first, the minimum mean square error (MMSE) scheme as interference cancellation methods used, and then the successive interference cancellation (SIC) is applied to obtain additional diversity gain and improve interference cancellation performance. Indoor VLC channel model is employed. The performance is evaluated in terms of bit error rate (BER). From the simulation results, it is confirmed that the proposed scheme has better BER performance compared to the previous systems. As a result, the proposed interference cancellation improves the signal quality of VLC systems by effectively removing the channel noise. The results of the paper can be applied to VLC for smart building and general communication systems.
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서성일,Seo, Sung-Il 한국인터넷방송통신학회 2021 한국인터넷방송통신학회 논문지 Vol.21 No.4
본 논문은 스마트 빌딩을 위한 가시광 통신 시스템에서 데이터 신뢰성을 향상시키는 딥러닝 기반의 간섭 제거 알고리즘에 대해 연구하였다. 본 논문에서 제안한 기법은 딥러닝 기술을 적용하여 채널에서 발생하는 잡음을 예측하여 제거하는 기술로서 수신단에서 딥러닝에 의해 학습된 잡음들을 활용하여 효과적으로 잡음을 제거함으로써 신호의 품질을 향상시킬 수 있다. 딥러닝 기술의 잡음 예측 정확도를 향상시키기 위해 기존의 잡음 형태를 데이터베이스화하여 활용하였다. 모의실험을 통해 간섭 제거 기법이 적용된 시스템 모델의 성능을 검증하였으며, 제안하는 시스템이 잡음을 효과적으로 제거하여 신호의 품질 성능을 향상시킬 수 있음을 확인하였다. 제안한 시스템 모델은 가시광 통신뿐만 아니라 일반적인 통신 시스템에서도 신호의 품질을 향상시킬 수 있도록 다양하게 적용이 가능하다. In this paper, we propose the deep learning based interference cancellation scheme algorithm for visible light communication (VLC) systems in smart building. The proposed scheme estimates the channel noise information by applying a deep learning model. Then, the estimated channel noise is updated in database. In the modulator, the channel noise which reduces the VLC performance is effectively removed through interference cancellation technique. The performance is evaluated in terms of bit error rate (BER). From the simulation results, it is confirmed that the proposed scheme has better BER performance. Consequently, the proposed interference cancellation with deep learning improves the signal quality of VLC systems by effectively removing the channel noise. The results of the paper can be applied to VLC for smart building and general communication systems.
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서성일 한국통신학회 2004 정보와 통신 Vol.21 No.4
미래 정보통신 환경이 광대역ㆍ초고속화되고 유ㆍ무선, 음성ㆍ데이타, 통신ㆍ방송간 통합 융합화가 활발히 진행됨에 따라 VoIP기술을 이용한 융합형 멀티미디어 통신서비스가 주요 통신서비스로 자리잡을 것으로 전망됨에 따라 인터넷전화(VoIP) 제도 및 계획에 대하여 소개하고자 한다.(중략)
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서성일,문지호,문형석 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.3
Submarine collisions is one of the major hazardous factor for Submerged Floating Railway Tunnel (SFRT) and this study presents the safety evaluation for submarine collision to SFRT by using theoretical approach. Simplified method to evaluate the collision safety of SFRT was proposed based on the beam on elastic foundation theory. Firstly, the time history load function for submarine collision was obtained by using one-degree-of-freedom vibration model. Then, the equivalent mass and stiffness of the structure were calculated, and the collision responses of SFRT were evaluated. Finite element analysis was conducted to verify the proposed equations, and it can be found that the collision responses, such as deflection, and acceleration, agreed well with the proposed equations. Finally, derailment condition for high speed train in SFRT due to submarine collision was proposed.
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Optimum design of the cored linear motor using experiment design
서성일,김낙수 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8
Recently, a linear motor has been becoming widely popular in office automation (OA) and factory automation (FA) systems due to its simple structure, high-speed operation, and precise positioning. In this study, a cored linear motor was designed to have a large thrust and small ripple because these are considered as indicators of motor performance. The thrust and ripple of the linear motor can be calculated by a finite element method (FEM) commercial program such as ANSYS. To design the cored linear motor, first, the design variables were selected through ANOM and ANOVA. The response surface method was applied to formulate the cost function of the second-order regression model, which can evaluate motor performance. By optimizing the cost function, it was possible to realize quickly the optimum design for a cored linear motor. As a result, the performance of the motor was improved.
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서성일,송시헌,김성호,김관태,김윤 대한신경외과학회 1995 Journal of Korean neurosurgical society Vol.24 No.2
The clinical analysis was carried out with 182 cases of craniocerebral injuries under 15 years of age, admitted at the Department of Neurosurgery, Chung Nam National Universty Hospital during the period from September, 1990 to September 1993. Following results were obtained : 1) There were 133 males and 49 females and sex ratio was 2.7% 2) Age incidence of the accidents was greatest at 6 years of age and mostly distributed to the age group between 4 to 7. 3) Seasonal peak of the accidents was at May. 4) The accident occurred mostly botween 4 P.m. and 6 P.m in a day.5) The most frequent cause of the craniocerebral injuries was traffic accident(105cases, 57.69%) 6) No deterioration of cansciousness before and after the admission was doserved in 68cases(37.36%) 7) Pupillary change was observed in 25 cases and Babinski sign was elicitable in 31cases 8) Early convulsion and vomiting were frequent symptoms in childhood. 9) Skull fracture was observed in 72 cases(39.56%) in which linear fracture was most frequent and predilection site was parietal bone. 10) The accompanying rate of skull fracture in intracranial hemorrhage was 65.54% 11) Associated injures were found in 44 cases(24.18%). The frequent ones were e xtremity fracture, clavicle fracture 12) The overall mortality was 7.14%.
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