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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).
2017년 제주시 대기 중 PM<sub>2.5</sub>의 화학적 조성과 오염원 추정
김수미 ( Su-mi Kim ),김길성 ( Kil-seong Kim ),현성수 ( Sung-su Hyun ),김정하 ( Jeong-ha Kim ),김명찬 ( Myeong-chan Kim ),김봉진 ( Bong-jin Kim ),이기호 ( Ki-ho Lee ) 한국환경분석학회 2018 환경분석과 독성보건 Vol.21 No.2
In this study, to characterize chemical compositions and identify the sources of PM<sub>2.5</sub> in the urban area of Jeju, Korea, PM<sub>2.5</sub>-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 PM<sub>2.5</sub> data-sets to identify the diverse sources in Jeju City. The average PM<sub>2.5</sub> mass concentration for the study period was 18.31±9.72 μg/m<sup>3</sup>. The contributions of water-soluble ionic species, elements and unknown components to PM<sub>2.5</sub> 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.
제주 스코리아로부터 합성된 Na-P1 제올라이트에 의한 2가 중금속 이온의 제거특성
감상규 ( Sang Kyu Kam ),현성수 ( Sung Su Hyun ),이민규 ( Min Gyu Lee ) 한국환경과학회 2011 한국환경과학회지 Vol.20 No.10
The removal performances of divalent heavy metal ions (Pb2+, Cu2+, Cd2+, Sr2+ and Mn2+) were studied using the Na-P1 zeolite synthesized from Jeju scoria in the batch and continuous fixed column reactor. The uptakes of heavy metal ions by synthetic Na-P1 zeolite decreased in the order of Pb2+>Cu2+>Cd2+>Sr2+>Mn2+ based on the selectivity of each ion to ionic exchange site of Na-P1 zeolite for single and mixed solutions in batch or continuous fixed column reactor. For mixed solution, each heavy metal ion uptake was lower than that in single solution, and especially the uptake for Mn2+ decreased greatly. In batch reactor, the uptakes of heavy metal ions by synthetic Na-P1 zeolite were described by Freundlich or Langmuir equation, but they followed the former better than the latter. In continuous fixed column reactor, the maximum ion exchange capacity obtained for each of heavy metal ions, was about 90% of that in batch reactor. The uptakes of heavy metal ions by synthetic Na-P1 zeolite increased with the increase of initial heavy metal concentration and solution pH, and the decrease of the amount and particle size of synthetic zeolite.
제주 스코리아로부터 합성된 제올라이트에 의한 납이온 흡착
감상규 ( Sang Kyu Kam ),현성수 ( Sung Su Hyun ),이민규 ( Min Gyu Lee ) 한국환경과학회 2011 한국환경과학회지 Vol.20 No.11
The adsorption performance of lead ion was studied using five zeolites (Na-P1, sodalite (SOD), analcime (ANA), nepheline hydrate (JBW), cancrinite (CAN)) synthesized from Jeju scoria. The adsorption performances of lead ion decreased in the order of Na-P1 > SOD > ANA > JBW > CAN. These results showed that the synthetic zeolite with a higher cationic exchange capacity showed a higher adsorption performance. The uptake of lead ion by synthetic zeolites were described by Freundlich model better than Langmuir model. The adsorption kinetics of lead ion by synthetic zeolites fitted the pseudo 2nd order kinetics better than pseudo 1st order kinetics. The effective diffusion coefficients of lead ion by synthetic zeolites were ten times higher than the zeolite A synthesized from coal fly ash.
김세라 ( Se Ra Kim ),현성수 ( Sung Su Hyun ),송상택 ( Sang Taek Song ),이민규 ( Min Gyu Lee ),감상규 ( Sang Kyu Kam ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.2
For 63 soil series distributed in Jeju Island, natural uncultivated soils in each soil series were collected, and their physicochemical properties and their concentrations of 19 heavy metals including 8 heavy metals which are regulated by Korean Soil Environment Conservation Law, were analyzed. Moreover, the correlations between physicochemical properties and heavy metal concentrations, and between heavy metal concentrations were analyzed. The heavy metals distributed in the higher concentrations and the lower concentrations with arithmetric mean value, were Mn(730 mg/kg) and Ba(493 mg/kg), and Hg(0.146 mg/kg) and Tl(0.096 mg/kg), respectively. The correlations between pH(H2O) and heavy metals(Hg, Ni, Co, Se), between pH(NaF) and heavy metals(Hg, Ba, Se, Tl), and between organic matter content and heavy metals(Hg, Tl) were significant at the 0.01 level. From the correlations between heavy metal concentrations, there were 22 where there were significant at the 0.01 level and they showed positive correlation. Among those, the heavy metals showing the correlation higher than r=0.5, were Sb-V(0.878), Mo-Sn(0.867), Co-V(0.654), Co-Sb(0.648), Be-Sn(0.546), and Sn-Tl(0.528).