• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.75-81
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• 2005

The GNUnet in P2P system have solved an anonymous(publisher, storer, demander); a service of condition equal for peer. The GNUnet for an anonymous has separated a file and dispersed to the network. But, the 1Kbyte block size of the GNUnet is a creation of many additional block. I and R block has created with indirect point of D block The waste of I and R block appeared to 4% of the original file and the additional network traffic for the block transmission. To resolve the problems, this paper proposes an new scheme of file splitting distribution using P2P networks with the new GNUnet protocol, The GNUnet support minimization of the additional block and for a network traffic. It proposed an efficiency improvement of encording block and routing algorithm.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.689-701
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• 2013

Bacterial growth and corresponding consumption of carbon and phosphorus were examined in which tap water samples containing a very low concentration of free chlorine were supplemented with organic carbon and/or phosphorus. The experiments were performed in a fed-batch mode under a controlled temperature of $20^{\circ}C$. In the phosphorus alone-added water, there was no significant increase in bacterial numbers measured as heterotrophic plate count (HPC) in the bulk water. However, bacterial growth was stimulated by the addition of carbon (e.g., bulk HPC levels increased to $10^3CFU/mL$) and further stimulated by the combined addition of carbon and phosphorus (e.g., bulk HPC to $10^5CFU/mL$). The same effects were observed in biofilm HPC and biomass formed on polyethylene (PE) slide surfaces. In the water where organic carbon and phosphorus were added together, the highest biofilm HPC and biomass (measured as extracellular polymeric substance components) densities were observed which were $7.6{\times}10^5CFU/cm^2$ and $5.3{\mu}g/cm^2$, respectively. In addition to the bacterial growth, additions of organic carbon and/or phosphorus resulted in different bacterial carbon-to-phosphorus (C/P) consumption ratios. Compared to a typical bacterial C/P consumption ratio of 100:1, a higher C/P ratio (590:1) occurred in the carbon alone-added water, while a lower ratio (40:1) in phosphorus alone-added water. Comparative value (80:1) of C/P ratio was also observed in the water where organic carbon and phosphorus were added together. At the given experimental conditions, bacterial growth was deemed to be more sensitive to microbially available organic carbon than phosphorus. The effect of phosphorus addition, which resulted in a lower C/P consumption ratio, seemed to be tightly associated with the presence of microbially available organic carbon. These results suggested that the control of extrinsic carbon influx seemed to be more important to minimize bacterial regrowth in drinking water system, since even low content of phosphorus naturally occurring in drinking water was enough to allow a bacterial growth.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.519-526
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• 2017

This study investigated the effect of phosphorus fractionation on the phosphorus release from the sediments of Juksan reservoir in Yeongsan River. The field sediments were collected, incubated, and analyzed with respect to phosphorus fractionation of sediments and total phosphorus (TP) of overlying water after 7 days. The total amount of inorganic phosphorus of YS2 site was higher than YS1 site. Al-P and Fe-P were major constituents of inorganic phosphorus. During the incubation, Al-P, Fe-P and Ca-P were increased and Red-P was decreased at both sites. YS1 site showed increased TP concentration of overlying water, however, YS2 had opposite trend during the incubation. Counting on the particle size distribution of YS1 and YS2, particle size distribution is major factor to control the TP concentration of overlying water. There were positive relationship between Fe-P and TP and negative relationship between Red-P. From the results, it is essential to continuously monitor the sediment phosphorus fraction in order to control the TP concentration of the water.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.428-434
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• 2016

This study evaluated the efficacy of Ti-based coagulants on phosphorus (P) removal from municipal wastewater and compared them with Al-based coagulants. Jar test experiments were performed at various chemical doses and OH/Ti molar ratio (B value). The higher the intial phosphate ($PO_4-P$) concentration, the lower the [Ti]/[P] to reach a residual concentration below 0.2 mg P/L. Removal efficiencies of total phosphorus increased with an increased coagulant dose but decreased after the efficiencies reached their maximum value regardless of coagulant or B value. On the other hand, $PO_4-P$ removal showed an increasing trend with an increased coagulant dose, reaching the plateau value under large coagulant dose conditions for both Ti- and Al-based coagulants regardless of B value. The chemical dose of Ti-based coagulants was approximately twice higher than that of Al-based coagulants with the same P-removal efficiency. The coagulation efficiency was influenced by different B values.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.259-261
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• 2000

본 연구는 사료내 인분해효소 phytase을 첨가하여 곡류내 유기태인의 이용성을 최대화하고 인의 배설량을 최소화하므로서 저공해성 산란계 사료 개발에 기초자료로서 활용하는데 목적이 있다. 부화 후 64주령된 갈색 하이라인 24수(평균체중 1.9kg, 산란율 78.4%)를 공시하였다. 대조구는 옥수수-대두박 위주로 배합된 사료, 처리구는 대조구 사료에 각각 phytase를 200 unit/kg, 400 unit/kg 그리고 600 unit/kg 첨가한 구로서 4처리 3반복, 반복당 2수씩 완전임의 배치하였다. 건물과 질소 이용률을 보면 처리간의 차이는 보이지 않았다(P>0.05). 광물질 중 회분과 칼슘의 경우 phytase를 200 unit을 첨가한 구에서 가장 높은 이용률을 보였다(P<0.05). 인의 이용률은 phytase를 600 unit 첨가한 구가 57.64%로 다른 처리구보다 이용률이 높은 것으로 나타났다(P<0.05). 칼슘의 섭취량과 배설량을 고려한 결과 칼슘의 축적량은 phytase를 200 unit와 400 unit 첨가한 구가 대조구와 phytase를 600 unit 첨가한 구보다 높았다(P<0.05). 산란계에 대한 각각의 인의 섭취량을 보면 phytase를 600 unit 첨가한 구가 대조구, 200 unit 첨가한 구, 400 unit 첨가한 구보다 많은 양을 섭취하였으나(P<0.05), 인의 배설량에는 별다른 차이가 없었다(P>0.05). 그로 인해 인의 축적량 또한 phytase를 600 unit 첨가한 구가 다른 처리구에 비해 많이 축적되었다(P<0.05). 혈중 칼슘의 함량은 phytase를 400 unit 첨가한 구와 600 unit 첨가한 구, 대조구간에는 서로 유의적인 차이가 없었고, phytase를 200 unit 첨가한 구보다 그 함량이 높게 나타났다(P<0.05). 결론적으로 산란계 사료에 phytase를 첨가할 때 환경문제를 야기시킬 수 있는 인의 배설량을 감소시키고 값비싼 무기태 인의 일부를 대체하는데 크게 기여할 수 있으리라 사료된다.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.840-850
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• 2010

The present study was attempted to find the effects of structural properties of phosphorus on the water quality of Gyehwa reservoir in Saemangeum. Relationship of phosphorus fractions between water and sediment properties was closely examined, and a few types of phosphorus were found from the sample sediment as : Saloid-P, Al-P, Fe-P, Ca-P, Red-P and Occd-P. Saloid-P (1.4%), Al-P (0.5%), Fe-P (39.8%), Ca-P (56.6%), Red-P (0.4%), Occd-P (1.3%) were extracted in a mass basis from the sediment of Gyehwa reservoir. Approximately more than 97% of phosphorus were calcium related phosphorus (Ca-P, 56%) and iron bound phosphorus (Fe-P, 39.8%). The Fe-P closely relates with water quality of T-N (r=0.761, p<0.05), $NO_3$-N (r=0.754, p<0.05), $NH_4$-N (r=0.728, p<0.05), T-P (r=0.774, p<0.05) and $PO_4$-P (r=0.767, p<0.05) while the Ca-P did not show any consistent dependency on the water quality. On the other hand, the correlation of Ca-P with $P_2O_5$ was high with r=0.783 (p<0.05) in the sediment. The Fe-P was affected significantly on the Ignition Loss (r=0.569, p<0.05), T-N (r=0.715, p<0.05) and T-P (r=0.983, p<0.01). In the research of correlation between phosphorus fraction and heavy metals in the sediment, Ca-P did not show any specific relationships with heavy metals. The Fe-P showed a significant correlation with As (r=0.817, p<0.01), Cu (r=0.793, p<0.05), Cd (r=0.786, p<0.05), Zn (r=0.738, p<0.05), so that it can be stated that the presence of Fe-P may implicate the volume of various metallic elements.

• Applied Biological Chemistry
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• v.43 no.2
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• pp.124-129
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• 2000

Nitrogen and P in surface runoff and eroded sediment from cropland areas can contaminate streams and lakes. Runoff losses of N and P were determined in a small field plot $(14.3{\times}24.8\;m)$ of peach orchard from March to November in 1999. Nitrogen and P were applied in the rate of 172 and 46 kg/ha using chemical fertilizer and mixed oil cake fertilizer. During the season, in 26 rainfall events, $421.5\;m^3/ha$ of runoff including 1,989 kg/ha of soil loss was collected. Concentrations of total-N, $NO_3-N$, $NH_4-N$, total-P and $PO_4-P$ in runoff samples were in the range of $4.7{\sim}171.0,\;0.1{\sim}188.0,\;0.13{\sim}3.36$, $0.58{\sim}4.99$ and $0.05{\sim}3.71\;mg/l$, respectively. Total loss of N was 16.39 kg/ha and 75% of the loss was $NO_3-N$. Total loss of P was 1.04 kg/ha, and $PO_4-P$ and sediment bound P accounted for 47 and 27% of the total loss, respectively. The losses of N and P were about 9.5 and 2.3% of the applied N and P in the plot, respectively. Although the loss of N or P would be relatively small in agricultural aspect, considering the high concentrations of N and P in runoff, loss of N and P from croplands should be controlled to reduce the eutrophication problem of stream waters.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.16-27
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• 2001

We have studied the phosphorus geochemistry in sediments from anoxic environments of Lake Shihwa. The dominant sedimentary phosphorus forms were detrital apatite P and Al-bound p, whereas the amount of Fe-bound P was low because of anoxic condition. Based on the correlation between TP(Total Phosphorus) and OC(Organic Carbon), the behavior of sedimentary phosphorus was influenced by organic matters. It shows that dissolved and solid phosphorus concentrations, the flux of phosphate and the correlation coefficients between sedimentary phosphorus and organic matter In St. Cl were higher than those in St. C2. The results indicate that the concentrations and distributions of phosphorus In sediments were controlled by organic matters.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.717-727
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• 2009

P2P (Peer-to-Peer) network depends on cooperation of peers considerably. However, some peers do not share files at all and only download files. Peers also share low quality files or unpopular files. These selfish behavior of peers is referred to 'free riding'. The free riding of peer may decrease participation of other peers or the system performance. In this paper, we propose an incentive mechanism, called IcMFS (Incentive Mechanism for File Sharing System), which provides the correct use of incentive mechanism using trust peer, computes contribution values referring behavior of peers and rewards peers. The proposed mechanism assigns bandwidth and TTL(Time-To-Live) to a peer and differentiates the use of service. A case study on simulations shows the service differentiation according to the contribution value of peer, the correct use of incentive mechanism using trust peer and the advantage by use of trust peer. To prove the stability of proposed mechanism, we also show the disadvantage that a peer receives from the incorrect use of incentive mechanism.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.673-678
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• 2009

High-rate phosphorous removal by PAC (poly aluminum chloride) coagulation of A2O effluent was investigate to meet the stringent requirement of wastewater discharge from municipal wastewater treatment plant. A series of jar tests were conducted to find optimum coagulation condition and to enhance removal efficiency. The optimum volumetric concentration of PAC was 30 ppm (2.81mol Al/mol P by mol ratio). Only 17.2% of soluble P was removed for 30 minutes' settling without PAC addition, while this increased to 30.3% by dosing 10ppm PAC. It even increased conspicuously from 49.3% to 88.4% by increasing PAC dose from 20 ppm to 30 ppm. 92.4% of total P was removed by 30 ppm PAC, and the effluent concentration (0.3 mg/L) was acceptable for discharge. The optimum value of coagulation time, settling time, and pH were 4minutes, 20 minutes, and 7.0, respectively. It was not necessary to control pH of raw sample whose pH was 7.0. Soluble P removal was remarkably enhanced at pH 7.0. This implied that sweep floc formation by $Al(OH)_3$ was the main mechanism of coagulation for soluble P removal. Influent and effluent of secondary clarifier were tested for coagulation, and the effluent was better for high-rate P removal. It resulted in 0.18 mg/L of P and 95.4% of P removal by coagulation. It was favorable to recycle the treated water to coagulation tank and the optimum recycle ratio was 0.3.