• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.157-172
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• 2011

The latest active studies on distributed OLAP to adopt a distributed environment are mainly focused on DHT P2P OLAP and Grid OLAP. However, these approaches have its weak points, the P2P OLAP has limitations to multidimensional range queries in the cloud computing environment due to the nature of structured P2P. On the other hand, the Grid OLAP has no regard for adjacency and time series. It focused on its own sub set lookup algorithm. To overcome the above limits, this paper proposes an efficient central managed P2P approach for a cloud computing environment. When a multi-level hybrid P2P method is combined with an index load distribution scheme, the performance of a multi-dimensional range query is enhanced. The proposed scheme makes the OLAP query results of a user to be able to reused by other users' volatile cube search. For this purpose, this paper examines the combination of an aggregation cube hierarchy tree, a quad-tree, and an interval-tree as an efficient index structure. As a result, the proposed cloud P2P OLAP scheme can manage the adjacency and time series factor of an OLAP query. The performance of the proposed scheme is analyzed by a series of experiments to identify its various characteristics.

• Hwankyungkyoyuk
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• v.21 no.3
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• pp.13-25
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• 2008

This study examined the educational effects of journal writing on environmental literacy of elementary students. Thirty-one 3rd grade students were involved in the journal writing which is considered as one of the most frequently performed writing activities in elementary students. Topics for the journal writing were chosen from a textbook on the environment. Before and after the journal writing, an instrument was used to measure the environmental literacy of the students. The environmental literacy instrument was originally developed by Jin (2004) then were modified by Kim (2005) for elementary students. The results of this study are as follows. The environmental literacy of the students, on average, was improved from 140.84 (74.5%) to 161.84 (85.6%) after the journal writing and the difference was statistically significant(t=7.46, p<.001). The environmental literacy scores were significantly improved in every variable after the journal writing: ecological knowledge(t=3.60, p<.01), environmental sensitivity(t=2.54, p<.05), knowledge of environmental issues(t=3.11, p<.01), environmental attitude(t=5.92, p<.001), environmental concern(t=5.27, p<.001), sense of environmental crisis(t=2.97, p<.01), environmental issue investigation and action strategy knowledge (t=2.34, p<.05), environmental skill(t=4.86, p<.001), locus of control(t=5.63, p<.001), and responsible environmental behavior(t=4.64, p<.001). This study also shows that improvement of the students was statistically significant in each of the four levels of goals in environmental education: EE goal level I (t=4.22, p<.001), level II (t=7.53, p<.001), level III(t=5.01, p<.001), and level IV(t=5.46, p<.001). The results imply that the journal writing on the environment is effective in cultivating elementary students' environmental literacy and in achieving goals in environmental education.

• Journal of Life Science
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• v.14 no.1
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• pp.32-37
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• 2004

A portion of ribosomal internal transcribed spacer (ITS) 2 was sequenced from the samples of Pseudo nitzschia (P. deticatissima, P. multiseries, P. pungens and P. subfraudulenta) to investigate the genetic characteristics by measuring tile magnitude of genetic diversity and the degree of similarity coefficient using random amplified polymorphic DNAs (RAPD)-PCR patterns. The phylogenetic trees inferred from the genetic distance analyses showed the placement of P. delicatissima formed a quite long distance from p. P. multiseries, P. pungens, and even P. subfraudulenta. The phylogenetic tree from RAPD patterns showed that P. multiseries and P. pungens had dissimilarity coefficient of 0.31, while P. delicatissima and three species of Pseudo-nitzschia had that of 0.81. It is likely thought that the genetic position of P. delicatissima formed far from P. multiseries, P. punges, and P. subfraudulenta. These results imply that ITS2 region is expected to support a useful molecular characters for recognizing at the species level and for even discriminating P. multiseries from P. pungens. RAPD method also will be used to differentiate the species of Pseudo-nitzschia in a short time.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.664-668
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• 2005

An experimental study for the comparison of nitrogen and phosphorus removal efficiencies between $A^2/O$ and modified Phostrip (M-Phostrip process) were carried out with bench-scale reactors. In case of nitrogen removal efficiencies both of processes showed similar ones when influent organic loadings were high. However, M-phostrip process was more effective than $A^2/O$ at low organic loadings. This is why M-phostrip process consumes the whole mass of influent organics as a carbon sources for denitrification in anoxic reactor but the anoxic reactor of $A^2/O$ process utilizes the residual carbon followed by consumming a part of influent carbon for phosphorus release in anaerobic reactor. $A^2/O$ process required the influent COD/T-P and COD/TKN ratios were more than 56 and 10, respectively, to take place the phosphorus release in anaerobic process and phosphorus uptake in oxic process. However, the luxury uptake of phosphorus in M-phostrip process was not affected by influent COD/T-P and COD/TKN ratios and the adverse effect of nitrate in return sludge introduced to the p-stripper from the 2nd clarifier was not significant due to the configurational advantage of the p-stripper.

• Journal of Internet Computing and Services
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• v.7 no.6
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• pp.87-103
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• 2006

Advances in computer and network technology provide new computing environment that were only possible with supercomputers before. In order to provide the environment, a distributed runtime system has to be provided, but most of the conventional distributed runtime systems lack in providing dynamic and flexible system reconfiguration depending on workload variance, due to a static architecture of fixed master node and slave working nodes. This paper proposes and implements a new model for distributed job allocation and management which is a distributed runtime system is P2P environment for flexible and dynamic system reconfiguration. The implemented systems enables job program transfer and management, remote compile and execution among cooperative developers based on P2P standard protocol Jxta platform. Since it makes dynamic and flexible system reconfiguration possible, the proposed method has some advantages in that it can collect and utilize idle computing resources immediately at a needed time for distributed job processing. Moreover, the implemented system's effectiveness and performance increase are shown by applying and processing the crawler jobs, in a distributed way, for collecting a large amount of data needed for internet search.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.448-450
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• 2003

P2P 환경의 파일 공유 서비스는 많은 사용자들에 의해 널리 이용됨으로써 거대한 분산 컴퓨팅 환경으로 이끌어 낸다. 이것은 기존의 파일 공유 서비스 이외에 프로세스 공유 측면에서도 좋은 환경을 제공할 수 있다. 이에 본 논문에서는 P2P의 파일 공유 서비스 사용 형태를 기반으로 프로세스 공유를 위한 협업시스템을 설계한다. 제시된 시스템은 P2P에서 발생가능한 Peer들간의 집중현상을 간접적으로 줄이고 다수의 Peef들 간의 분산된 컴퓨팅 능력을 제공함으로써 기존 파일 공유 환경에 효율적인 분산환경을 제공할 수 있다.

• Journal of Korean Society on Water Environment
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• v.37 no.2
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• pp.114-127
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• 2021

Water pollution in the lower reaches of the Namhan River is getting worse due to drought and a decrease in water quantity due to climatic changes and hence is affecting the water quality of Paldang Lake. Accordingly, we have used a water quality index (WQI) and statistical analysis in this study to identify the characteristics of the water quality in the lower reaches of the Namhan River, the main causes of water pollution, and tributaries that need priority management. Typically, 10 items (WT, pH, EC, DO, BOD, COD, SS, T-N, T-P, and TOC) were used as the water quality factors for the statistical analysis, and the matrix of data was set as 324 × 10·1. The correlation analysis demonstrated a strong correlation between Chemical Oxygen Demand (COD) and T-P with a high statistical significance (r=0.700, p<0.01). Furthermore, the result of principal component analysis (PCA) revealed that the main factors affecting the change in water quality were T-P and organic substances introduced into the water by rainfall. Based on the Mann-Kendall test, a statistically significant increase in pH was observed in SH-1, DL, SH-2, CM, and BH, along with an increase in WQI in SH-2 and SM. BH was identified as a tributary that needs priority management in the lower reaches of the Namhan River, with a "Somewhat poor" (IV) grade in T-P, "Fair" grade in WQI, and "Marginal" grade in summer.

• Research in Plant Disease
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• v.11 no.2
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• pp.193-197
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• 2005

The effect of pH on the survival of R. solanacearum and its transmission via roots of tomato in hydroponic culture were studied in laboratory and greenhouse. In laboratory experiment, R. solanacearum could not survive for 24h in nutrient solution with pH of $4{\cdot}0;or\;4{\cdot}5$, while 1, 14, 51 and $62\%$ of inoculum survived at pH $5{\cdot}0,\;5{\cdot}6\;and\;6{\cdot}5$, respectively. When tomato plants were inoculated with R. solanacearum through wounds on the stems, the bacteria moved downward from the inoculation site to the roots and infectious bacteria were released from the roots into the nutrient solution. Of two pH regimes tested in greenhouse nutrient-film technique(NFT) culture, the R. solanacearum population was significantly lower in pH 5.0 than in pH 6.5 in most sampling data. In treatments in which R. solanacearum was introduced by transplanting two root-inoculated plants, significantly move plants developed wilt at pH $6{\cdot}5$(34 out of 48 plants) than at pH 5.0(11 out of 48 plants). In addition, when the bacterium was introduced by transplanting two stem-inoculated plants at pH $6{\cdot}5$, seven out of 24 plants developed wilt.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.69-78
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• 2005

As the study and use of P2P systems are diversified, the effect of excessive amount of traffic, which occurs in searching peers' resource and is considered as a network bandwidth Problem, cannot let the matter Pass without making a protest. In case P2P application doesn't reduce network traffic, it can be much effected to use bandwidth smoothly in the internet environment where various network applications lie scattered and there will be inconvenience when many network users makes use of related applications . In this Paper, we propose a pure P2P model based-broadcasting technique for producing successful hit ratio and traffic amount in the weakly connected environment based-P2P system where situation of peers' connection and exit is ambiguous . The proposed searching technique is designed/implemented to improve a resident problem in the related system and we have estimated the performance of the proposed searching technique comparing our technique with the existing broadcasting based-searching technique .

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.619-624
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• 2015

This study experimentally determined the effect of titanium tetrachloride (TiCl₄) concentration ([TiCl₄]) (0.25-0.55 mM) and initial pH (3-11) on phosphorus (P) removal in synthetic wastewater (2 mg P/L). The P removal efficiency increased when [TiCl₄] increased. The P removal efficiency showed a parabolic trend with an inflection point at pH 7. At the molar ratio of TiCl₄ and P>6.2, the P removal efficiency was over 90% and the residual P concentration was less than 0.2 mg/L. Within the design boundaries, the complete P removal could be achieved at 7.0≤initial pH≤8.5 and 0.43≤[TiCl₄]≤0.55 mM. The final pH was over 5.8 at initial pH≥7.7 and [TiCl₄]≥0.35 mM. The results showed that TiCl4 was effective in P removal in water so that it could be an alternative chemical for P removal.