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페이딩 채널에서 확률 질량 함수를 이용한 인터리빙 파라미터 블라인드 추정
김근배(Geunbae Kim),장연수(Yeonsoo Jang),윤동원(Dongweon Yoon) 한국정보기술학회 2019 한국정보기술학회논문지 Vol.17 No.5
In order to analyze received data in a non-cooperative communication environment, blind estimation of interleaving parameter is required. The previous estimation algorithms estimated interleaving period by exploiting the linear property between the message bits and parity bits of error correction code in noisy channel. In this paper, we improve the performance of interleaving period estimation in fading channel comparing the rank distribution between square matrix composed of received data and that of random data by using probability mass function. The estimation performance is measured by detection probability and false alarm probability and compared with that of the previous algorithms in Rayleigh fading channel through computer simulations.
순환 주파수 추정을 통한 직접 시퀀스 대역 확산 신호 탐지 알고리즘 복잡도 저감
김윤지(Yoonji Kim),김근배(Geunbae Kim),강현진(Hyunjin Kang),김재윤(Jaeyun Kim),윤동원(Dongweon Yoon) 한국정보기술학회 2022 한국정보기술학회논문지 Vol.20 No.1
For a non-cooperative context, it is difficult to detect the direct sequence spread spectrum (DSSS) signal at the receiver when the spreading code is unknown due to its low probability of intercept characteristic. To detect the DSSS signal, the detection algorithm exploiting the cyclostationarity of the DSSS signal was proposed, which shows good detection performance in a channel with low signal-to-noise ratio. However, this algorithm requires a long time to detect signals because of its high computational complexity. In this paper, we propose an improved algorithm that can reduce the complexity by first estimating the cyclic frequencies of the incoming signal. Through computer simulations, we verify that the proposed algorithm can show the same detection performance as in conventional algorithms with lower computational complexity.
어린이집에서 이산화탄소와 미세먼지의 장기간 시간적인 변이를 활용한 실내환경수준 평가
김윤지(Yoonjee Kim),이세원(Sewon Lee),반현경(Hyunkyung Ban),차상민(Sangmin Cha),김근배(Geunbae Kim),이기영(Kiyoung Lee) 한국환경보건학회 2017 한국환경보건학회지 Vol.43 No.4
Objectives: The purposes of the study were to analyze the temporal variation of carbon dioxide (CO 2 ) and particulate matter (PM) in daycare centers and evaluate the appropriateness of the official test method of onetime measurement. Methods: Indoor air quality in 46 daycare centers in the Seoul Metropolitan Area was measured as specified in the official test method of Indoor Air Quality Management law. In addition, indoor air quality in the 46 daycare centers was measured over 37 days using a real-time monitor (AirGuard K). Results: The daily means of CO 2 and PM in the 46 daycare centers were 1042.74 ± 134.45 ppm and 67.60 ± 18.25 µg/m 3 , respectively. Indoor air quality in the daycare centers showed significant temporal fluctuation. Measurements for single days were significantly different from the 37-day average exposure. Relative error of short term exposure decreased with an increase in the number of sampling days. The noncompliance rate for CO 2 using the official testing method was 2.17%, and none exceeded the PM 10 standard of 100 µg/m 3 . With monitoring over 37 days, the daily noncompliance rate for CO 2 was 50.4% and the daily noncompliance rate for PM was 13.8%. Conclusions: When the official test method evaluates the indoor air at daycare centers one day per year, the results may not represent actual indoor air quality over a longer period of time. Real-time monitoring devices could be an alternative for managing indoor air quality.
신평·장림 산단 인근 주민의 PAHs 및 VOCs 노출
윤미라(Mi-Ra Yoon),조혜정(HyeJeong Jo),김근배(GeunBae Kim),장준영(JunYoung Chang),이철우(Chul-Woo Lee),이보은(Bo-Eun Lee) 한국환경보건학회 2021 한국환경보건학회지 Vol.47 No.2
Objectives: This study aims to investigate the atmospheric concentration of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) and the urinary concentration of biomarkers in residents near the Shinpyeong·Jangrim Industrial Complex to compare them with those of residents in a control area. Methods: Hazardous air pollutants (PAHs and VOCs) were measured in an exposure area (two sites) and a control area (one site). Urine samples were collected from residents near the industrial complex (184 persons) and residents in the control area (181 persons). Multiple linear regression analysis was used to identify which factors affected the concentration of PAHs and VOCs metabolites. Results: The average atmospheric concentration of PAHs in Shinpyeong-dong and Jangrim-dong was 0.45 and 0.59 ppb for pyrene, 0.15 and 0.16 ppb for benzo[a]pyrene, and 0.29 and 0.35 ppb for dibenz[a,h]anthracene. The average atmospheric concentration of VOCs was 1.10 and 0.99 ppb for benzene, 8.22 and 11.30 ppb for toluene, and 1.91 and 3.05 ppb for ethylbenzene, respectively. The concentrations of PAHs and VOCs in residents near the Shinpyeong·Jangrim Industrial Complex were higher than those of residents in the control area. Geometric means of urinary 2-hydroxyfluorene, 1-hydroxypyrene, methylhippuric acid, and mandelic acid concentrations were 0.45, 0.22, 391.51, and 201.36 μg/g creatinine, respectively. Those levels were all significantly higher than those in the control area (p<0.05). In addition, as a result of multiple regression analysis, even after adjusting for potential confounding factors such as gender and smoking, the concentration of metabolites in urine was high in residents near the Shinpyeong·Jangrim Industrial Complex. Conclusion: The results of this study show the possibility of human exposure to VOCs in residents near the Shinpyeong·Jangrim Industrial Complex. Therefore, continuous monitoring of the local community is required for the management of environmental pollutant emissions.