http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Md. Moklesur Rahman (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
-
Rahman, MD. Moklesur,Lee, Yong-gu,Kim, Guebuem,Lee, Kitack,Han, Seunghee Elsevier 2013 CHEMOSPHERE - Vol.91 No.3
<P>Submarine groundwater discharge (SGD) and various solutes released with SGD have received particular attention recently; however, understanding of the impact of SGD on trace metal fluxes in the coastal ocean is limited. To understand the contribution of SGD to the coastal Hg input, the Hg mass fluxes associated with SGD were estimated from Hampyeong Bay, a coastal embayment in the Yellow Sea. Hg concentrations in filtered groundwater and seawater ranged from 1.3 to 4.4pM and from 0.83 to 2.0pM, respectively, and Hg concentrations in unfiltered seawater ranged from 1.7 to 4.6pM. The Hg flux estimation showed that SGD was the prime input source of Hg in the bay (1812molyr(-1)), contributing 65% of the total input. Atmospheric deposition was the second dominant source of Hg (8.52.7molyr(-1)), contributing 31% to the total input. The results of the current study suggest that SGD can be a significant source of Hg in estuarine/coastal systems; therefore, estimating the coastal mass budgets of Hg must include SGD as a prime source of Hg.</P>
-
Ku대역과 밀리미터 대역의 광대역 무선통신 시스템을 위한 소형 슬롯 6각 구조의 패치 안테나
Md. Moklesur Rahman,박병학(Byounghak Park),유흥균(Heung-Gyoon Ryu) 대한전자공학회 2021 전자공학회논문지 Vol.58 No.8
본 논문에서는 초광대역의 소형 슬롯 6각 구조의 패치 안테나가 12×9×0.787 ㎣ (1.64λ×1.23λ×0.107λ)로 설계되었다. 본 논문에서는 위성통신과 66.67%의 중심 주파수 비 대역폭을 가지는 미래 ㎜-Wave 어플리케이션을 위해 (30 ~ 52) ㎓의 대역보다 더 넓은 초광대역 통신을 위해 슬롯 6각 구조의 ground plane이 Ku대역 주파수(17.608 ~ 19.64) ㎓에서 동작되도록 제시했다. 안테나는 37 ㎓의 ㎜-Wave 주파수 대역을 포함하여 다양한 주파수에서 공진한다. 제안된 안테나의 최대 이득은 6.282 ㏈이다. In this paper, a compact ultra-wideband slotted hexagonal patch antenna is presented whose overall dimension of 12x9x0.787 ㎣ (1.64λx1.23λx0.107λ). This paper also presented, a slotted hexagonal ground plane to operate in the Ku-band frequency (17.608 ~ 19.64) ㎓ for satellite communication, and in the ultra-wideband which has larger operating frequency bandwidth of (30 ~ 52) ㎓ for future mm-wave applications with the fractional bandwidth of 66.67%. The antenna resonates at different frequencies including the mm-Wave frequency band of 37 ㎓. The maximum gain of the proposed antenna is 6.282 ㏈i.
-
-
ESPAR Antenna Array for the RFID based WSN Communication with Interference
Md. Moklesur Rahman,Heung-Gyoon Ryu(유흥균) 대한전자공학회 2022 전자공학회논문지 Vol.59 No.6
본 논문에서는 UHF(Ultra-High Frequency) 대역의 RFID(Radio Frequency Identification) 통신 시스템에서 RSS(Received Signal Strength) 및 신호 품질 향상을 위한 ESPAR(Electronically Steerable Parasitic Array Radiator) 안테나를 설계한다. 일반적으로 단일 안테나와 비교하여, 안테나 배열 기술은 더 높은 이득과 우수한 빔 패턴 특성으로 인하여 최근 많은 통신 시스템에서 널리 사용되고 있다. 본 논문에서는 ESPAR 안테나 배열의 빔포밍 제어를 통해 만들 수 있는 안테나 널링(Nulling) 기술을 통해 간섭과 다중경로 패이딩을 극복하기 위한 새로운 UHF RFID 기반 무선 센서 네트워크 통신을 고려한다. 제안된 시스템에서 설계된 ESPAR 안테나 배열은 더 높은 빔 이득과 우수한 빔 패턴 모양을 보여준다. 그리고 무선 채널에서 간섭이 최소화된다. 제안하는 시스템은 더 높은 정확성과 더 넓은 통신 범위, 그리고 배터리 사용 시간의 확장 특성을 갖으므로, 다수의 무선 ECG(Electrocardiogram) 모니터링 시스템과 후방산란 통신 시스템 등에 적용될 수 있다. In this paper, in order to improve the received signal strength (RSS) and signal quality, an array of Electronically Steerable Parasitic Array Radiator (ESPAR) antenna is designed for the Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) communication system. Compared with the single antenna, the array antenna is widely used in the recent communication systems due to its advantages as like higher gains, and better radiation patterns, increased power efficiency. In this paper, a new UHF RFID based wireless sensor network communication is considered to overcome the interference and multipath fading by antenna nulling technology that can be made by beam forming control of ESPAR array antennas. The designed array of ESPAR antennas in the proposed system exhibits higher gain and proper radiation pattern. The interference is minimized by modeling wireless channel, considering antenna noise, and optimum signal to noise ratio based on the link budget. This proposed system can be applied into the massive wireless ECG (Electrocardiogram) monitoring system and in the backscatter communication applications since it can show the better advantages such as higher accuracy, wider range and the longer battery life span.
-
ESPAR Antenna for Long Distance WSN Systems with Minimum Interference
Md. Moklesur Rahman,유흥균 한국통신학회 2022 韓國通信學會論文誌 Vol.47 No.9
Recently, radio frequency identification (RFID) with ultra-high frequency (UHF) band applications became an essential part in the Internet of Things (IoT) system. Wireless sensor networks (WSNs) are an integral part of the IoT. Nowadays, it is very important to design the WSN system model in longer distance with minimum interference and optimum signal-to-noise ratio (SNR) for better communications link. In this paper, we have proposed the architecture of WSN system by designing electronically steerable parasitic array radiator (ESPAR) antenna for minimum interference. Also, the link budget (LB) for distance depending on different SNR values between the RFID tag and reader are analyzed using MATLAB simulation tools. The ESPAR antenna shows very good performance based on gain, radiation pattern, and reflection coefficient. The maximum value of gain of the proposed ESPAR antenna is obtained as 7.55 dBi which will successfully handle the interference at any directions to be communicated over long distance as compared to the previously published once papers in WSN system. The link budget analysis spectacled that the proposed article in the indoor environment could easily be applied for 20 meter.
-
Lee, Yong-gu,Rahman, MD. Moklesur,Kim, Guebuem,Han, Seunghee American Chemical Society 2011 Environmental science & technology Vol.45 No.23
<P>To understand the contribution of submarine groundwater discharge (SGD) to the coastal mass budgets of Hg and monomethylmercury (MMHg), preliminary mass balance estimates were made for Hwasun and Bangdu Bays on Jeju Island, known to have large SGD due to the high permeability of the volcanic rocks. The mass balance results indicate that SGD is a main source of Hg in Hwasun Bay (23 ± 14 × 10<SUP>–2</SUP> mol yr<SUP>–1</SUP>, 34%) and Bangdu Bay (23 ± 20 × 10<SUP>–2</SUP> mol yr<SUP>–1</SUP>, 67%), although the contribution from atmospheric deposition was considerable (25% for Hwasun and 23% for Bangdu). MMHg was also discharged primarily from submarine groundwater at Hwasun (0.30 ± 0.17 × 10<SUP>–2</SUP> mol yr<SUP>–1</SUP>, 55%) and Bangdu (0.65 ± 0.49 × 10<SUP>–2</SUP> mol yr<SUP>–1</SUP>, 64%), which was higher than atmospheric deposition (6% for Hwasun and 2% for Bangdu) and sediment diffusion flux (5% for Hwasun and 3% for Bangdu). The overall mass balance results suggest that, although there are large spatial variations in SGD rates throughout the region, the coastal mass budgets of Hg and MMHg need to include SGD as well as atmospheric deposition and sediment diffusion as primary sources of Hg and MMHg.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2011/esthag.2011.45.issue-23/es202093z/production/images/medium/es-2011-02093z_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es202093z'>ACS Electronic Supporting Info</A></P>
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
