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전자공여체와 황산염 이용 토착미생물에 의한 침철석(α-FeOOH) 환원 연구
권만재,양중석,심무준,이승학,Maxim Boyanov,Kenneth Kemner,Edward O'Loughlin 한국지하수토양환경학회 2014 지하수토양환경 Vol.19 No.1
To better understand dissimilatory iron and sulfate reduction (DIR and DSR) by subsurface microorganisms, we investigated the effects of sulfate and electron donors on the microbial goethite (α-FeOOH) reduction. Batch systems were created 1) with acetate or glucose (donor), 2) with goethite and sulfate (acceptor), and 3) with aquifer sediment (microbial source). With 0.2 mM sulfate, goethite reduction coupled with acetate oxidation was limited. However, with 10 mM sulfate, 8 mM goethite reduction occurred with complete sulfate reduction and x-ray absorption fine-structure analysis indicated the formation of iron sulfide. This suggests that goethite reduction was due to the sulfide species produced by DSR bacteria rather than direct microbial reaction by DIR bacteria. Both acetate and glucose promoted goethite reduction. The rate of goethite reduction was faster with glucose, while the extent of goethite reduction was higher with acetate. Sulfate reduction (10 mM) occurred only with acetate. The results suggest that glucose-fermenting bacteria rapidly stimulated goethite reduction, but acetate-oxidizing DSR bacteria reduced goethite indirectly by producing sulfides. This study suggests that the availability of specific electron donor and sulfate significantly influence microbial community activities as well as goethite transformation, which should be considered for the bioremediation of contaminated environments.
CR X-선 영상기법을 이용한 DPF 파손여부에 대한 비파괴 측정 타당성 연구
권만재(Manjae Kwon),박기영(Giyoung Park),김성준(Sungjoon Kim),한태호(Taeho Han),김정민(Jungmin Kim),이성욱(Seangwock Lee) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.9
Diesel vehicles are equipped with after-treatment devices, such as DPF. Meanwhile, DPF is damaged by a combination of regenerative processes and unclear factors. If the DPF substrate is damaged, the filtration performance will deteriorate, thereby resulting in excessive levels of fine dust being emitted while driving. In this study, CR X-ray techniques were used in order to determine whether a DPF was damaged without prior removal. In order to verify the technological feasibility, an X-ray imaging of the DPF removed from the driving vehicle was conducted by using an X-ray generator, as well as an IP reader and a CR reader. Optimal irradiation conditions were established for each DPF size. Verification of images acquired under optimal irradiation conditions confirmed the possibility of diagnosis for damages, such as crack, melting, and hollow damage.
직선과 원호가 결합된 WLAN/WiMAX용 삼중대역 안테나 설계 및 제작
권만재(Man Jea Kwon),윤중한(Joong Han Yoon) 한국전자통신학회 2018 한국전자통신학회 논문지 Vol.13 No.1
본 논문에서는 WLAN/WiMAX 시스템에 적용 가능한 모노폴 안테나를 제안하였다. 제안된 안테나는 두 개의 원호와 한 개의 직선 선로로 설계하여 세 개의 전류흐름을 갖도록 구성하여 세 개 대역의 공진특성을 갖도록 설계하였다. 두 개의 원호 길이와 한 개의 직선 선로의 길이를 상호결합을 고려하려 본 논문에서 요구되는 특성을 얻기 위한 최적화 수치를 얻었다. 제안된 안테나는 23.5 mm(W1)×32.0 mm(L1)×1.0 mm(t)의 유전율이 4.4인 RF-4 기판 위에 21.0 mm (W6) × 31.0 mm (L7)의 크기로 제작되었다. 측정결과로부터, 927 MHz(1.844~2.771 GHz), 926 MHz (3.33~4.256 GHz), 그리고 1,415 MHz (5.13~6.545 GHz)의 대역폭을 얻었다. 또한 요구되는 삼중대역에서 측정된 이득과 방사패턴의 얻었다. In this paper, a microstrip-fed triple-band monopole antenna for WLAN/WiMAX applications was proposed. The proposed antenna is consist of two arc-shaped and one strip line structure, then get the three current path and then designed in order to get triple resonant characteristics. We carried out simulation about parameters. Taking account of coupling effect, Adjusted the length of the two arc-shaped and one strip line, we get the optimized parameters. The proposed antenna is fabricated on an FR-4 substrate, the dielectric constant is 4.4, and total size is 23.5 mm(W1) × 32.0 mm(L1) × 1.0 mm(t), and its proposed antenna size is 21.0 mm(W6) × 31.0 mm(L7). From the measured results, return loss of the proposed antenna satisfied return loss 927 MHz (1.844~2.771 GHz), 926 MHz (3.33~4.256 GHz), and 1,415 MHz (5.13~6.545 GHz). And measured results of gain and radiation patterns displayed for operating bands.