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DTN에서 Hybrid Spray and Wait 라우팅 프로토콜
현성수 ( Sung-su Hyun ),정현진 ( Hyeon-jin Jeong ),최승식 ( Seoung-sik Choi ) 한국인터넷정보학회 2014 인터넷정보학회논문지 Vol.15 No.3
DTN(Delay/Disruption Tolerant Network)은 행성과 행성 간의 통신, 행성과 인공위성과의 통신과 같이 종단 간 연결이 보장되지 않고, 빈번한 연결 부재가 발생하고 기존 인터넷 인프라가 충분히 갖춰지지 않는 네트워크에 적합한 차세대 네트워크이다. 본 논문에서는 DTN 환경에서의 노드 간에 접촉한 기록 데이터를 이용하여 주기적으로 만나는 것을 확인하고, 향후 만나는 시간을 예측하여, 예측한 시간을 토대로 메시지를 누구에게 보내야 효율적인지를 선별하여, 메시지를 보내도록 한다. 또한 기존 라우팅 기법인 Spray and Wait 라우팅을 선별된 노드에게 적용하는 Hybrid Spray and Wait 알고리즘을 제안한다. 제안 알고리즘을 검증하기 위해 헬싱키 대학의 ONE(Opportunistic Network Environment) Simulator를 이용하여 이를 실험하였다. 제안하는 알고리즘의 전달성공률을 Binary Spray and Wait 라우팅의 성능과 비교하였고, 10% 적은 오버헤드를 보임을 확인하였다. 또한 불필요한 메시지의 복사를 줄일 수 있음을 확인하였다. DTN is the next generation network that is used in not guaranteed end-to-end connection such as communication between planet and satellite, frequent connection severance, and not enough for qualified network infrastructure. In this paper, we propose the hybrid Spray-and-Wait algorithm to predict the node contact time by monitoring the periodic contacts information between the nodes. Based on this method, we select one node on the basis of prediction time and copy a message for spray and wait algorithm. In order to verify the the hybrid Spray and Wait algorithm, we use the ONE(Opportunistic Network Environment) Simulator of Helsinki University. The delivery probability of the proposed algorithm is compared to the Binary Spray and Wait algorithm, it is showed that it has 10% less overhead than Binary Spray and Wait routing. It has also shown that it reduces unnecessary copying of this message.
현성수 ( Sung-su Hyun ),김세라 ( Se-ra Kim ),이민규 ( Min-gyu Lee ),감상규 ( Sang-kyu Kam ) 한국환경과학회 2017 한국환경과학회지 Vol.26 No.7
For 26 soil series distributed more than 1% among 63 soil series in Jeju Island, natural uncultivated soil samples were collected. For these soils, the chemical speciation of eight heavy metals (Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn) was examined. Further, the Plant Bioavailability (PB) and Mobility Factor (MF) of these heavy metals were evaluated using Tessier`s 5-step sequential extraction method (exchangeable, carbonate, reducible (bound to Fe/Mn oxides), oxidizable (bound to organic matter), and residual fraction). The main form present was residual fraction for Cd and Zn; residual and oxidizable fractions for Cr, Cu, Ni, and Pb; reducible fraction for Mn; and carbonate fraction for V. The average plant availability and average mobility factor were found to be V (57.37%) > Zn (12.49%) > Cd (11.76%) > Cu (11.19%) > Pb (9.37%) > Cr (9.09%) > Mn (3.13%) > Ni (2.63%), and Mn (61.04%) > V (59.94%) > Zn (31.54%) > Cd (17.65%) > Cr (15.66%) > Ni (13.89%) > Pb (13.80%) > Cu (13.53%), respectively.
제주 스코리아로부터 합성한 제올라이트 물질에 의한 암모니아성 질소의 흡착 특성
이창한,현성수,감상규,Lee, Chang-Han,Hyun, Sung-Su,Kam, Sang-Kyu 한국환경과학회 2020 한국환경과학회지 Vol.29 No.12
The characteristics of ammonia-nitrogen (NH4+-N) adsorption by a zeolitic material synthesized from Jeju scoria using the fusion and hydrothermal method was studied. The synthetic zeolitic material (Z-SA) was identified as a Na-A zeolite by X-ray diffraction, X-ray fluorescence analysis and scanning electron microscopy images. The adsorption of NH4+-N using Jeju scoria and different types of zeolite such as the Z-SA, natural zeolite, and commercial pure zeolite (Na-A zeolite, Z-CS) was compared. The equilibrium of NH4+-N adsorption was reached within 30 min for Z-SA and Z-CS, and after 60 min for Jeju scoria and natural zeolite. The adsorption capacity of NH4+-N increased with approaching to neutral when pH was in the range of 3-7, but decreased above 7. The removal efficiency of NH4+-N increased with increasing Z-SA dosage, however, its adsorption capacity decreased. For initial NH4+-N concentrations of 10-200 mg/L at pH 7, the adsorption rate of NH4+-N was well described by the pseudo second-order kinetic model than the pseudo first-order kinetic model. The adsorption isotherm was well fitted by the Langmuir model. The maximum uptake of NH4+-N obtained from the Langmuir model decreased in the order of Z-CS (46.8 mg/g) > Z-SA (31.3 mg/g) > natural zeolite (5.6 mg/g) > Jeju scoria (0.2 mg/g).
제주 스코리아로부터 합성된 Na-P1 제올라이트에 의한 Cu 이온 제거
감상규,홍정연,현성수,안병준,이민규 한국환경과학회 2002 한국환경과학회지 Vol.11 No.1
The removal performance of copper ion was studied using Na-Pl zeolites synthesized from Jeju scoria. The scoria which is found in large amounts in Jeju Island, was sampled at four regions, Jeju-shi Bonggae-dong(A), Pukcheju-gun Hanlim-eup Sangmyong-ri Mangoreum(B), Pukcheju-gun Hanlim-eup Keumag-ri(C) and Namcheju-gun Andeok-myun Dongkwang-ri(D). Synthetic Na-PI zeolites used in this study were more effective than natural zeolite and scoria for the removal of copper ion. The removal performances of copper ion decreased in the order of Na-Pl(D) > Na-Pl(C) > Na-Pl(B) > Na-Pl(A) among Na-Pl synthesized from the scoria according to region. These results showed the same trend with cation exchange capacity(CEC) for each synthetic zeolite, i.e., the synthetic Na-PI zeolite with a higher CEC showed a higher removal performance. The effective diffusion coefficients of copper ion by synthetic Na-Pl zeolites were one hundred and ten times higher than those by a pure zeolite 4A and the zeolite A synthesized from coal fly ash, respectively.
2017년 제주시 대기 중 PM2.5의 화학적 조성과 오염원 추정
김수미,김길성,현성수,김정하,김명찬,김봉진,이기호 한국환경분석학회 2018 환경분석과 독성보건 Vol.21 No.2
In this study, to characterize chemical compositions and identify the sources of PM2.5 in the urban area of Jeju, Korea, PM2.5-bound concentrations of 8 ionic species and 12 elements were measured from samples collected at the downtown area from January to December 2017. Positive matrix factorization (PMF) was applied to these PM2.5 data-sets to identify the diverse sources in Jeju City. The average PM2.5 mass concentration for the study period was 18.31±9.72 µg/m3. The contributions of water-soluble ionic species, elements and unknown components to PM2.5 mass were 55.8%, 2.1%, and 42.0%, respectively. PMF analysis showed that a total of six source types were identified to be important. These sources are the industry related source, secondary sulfate and oil combustion, soil, biomass burning and vehicles, secondary nitrate, and sea salt.