• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.2
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• pp.160-167
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• 1987

This paper proposes a CS/MLBP(carrier sence/message and location based priority) reservation sheme in integrated data/voice local area networks. In this sceme reservation can be done with only 2 reservation bits regardless of the total number of stations in the network. Thus the reservation time is shorter than that of DSMA scheme(6) where reservation time is proportional to the logarithm of the total number of stations. Simulation results show that, as compared to DSMA scheme, this control scheme improves th delay-throughput characteristics of both the data and the voice traffic, reduces the lossrate of voice packet at heavy load. Results also show that the performance of the propoxed scheme is independant of the total number of the stations allowed.

• The Journal of Fisheries Business Administration
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• v.46 no.1
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• pp.93-107
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• 2015

This study aims to analyze causalities among Hairtail prices by distribution channel using a vector autoregressive model. This study applies unit-root test for stability of data, uses Granger causality test to know interaction among Hairtail Prices by distribution channel, and employes the vector autoregressive model to estimate statistical impacts among t-2 period variables used in model. Analyzing results of this study are as follows. First, ADF, PP, and KPSS tests show that the change rate of Hairtail price by distribution channel differentiated by logarithm is stable. Second, a Granger causality test presents that the producer price of Hairtail leads the wholesale price and then the wholesale price leads the consumer price. Third, the vector autoregressive model suggests that the change rate of Hairtail producer price of t-2 period variables statistically, significantly impacts change rates of own, wholesale, and consumer prices at current period. Fourth, the impulse response analysis indicates that impulse responses of the structural shocks with a respectively distribution channel of the Hairtail prices are relatively more powerful in own distribution channel than in other distribution channels. Fifth, a forecast error variance decomposition of the Hairtail prices points out that the own price has relatively more powerful influence than other prices.

• Progress in Medical Physics
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• v.7 no.1
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• pp.25-35
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• 1996

Optical measurements of turbid biological tissue have provided a means to study tissue metabolism, tissue blood perfusion and blood oxygenation non-invasively. We used the red light of 660nm and infrared of 880nm to measure the blood fractional volume and oxygen saturation of biological tissue. In vivo reflectance data were obtained the physiological change from the deep tissue in human subject. The data evaluation was assessed by examining the slopes of the plotter index for the changes in oxygen saturation and blood fraction volume. The index is the natural logarithm of the ratio of reflected light intensity from measured medium to reference intensity at each wavelength. According to the experimental results, oxygen index changes significantly in the muscle of calf during exercise.

• Journal of The Korean Association For Science Education
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• v.30 no.7
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• pp.920-932
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• 2010

Many topics in science, especially, abstract concepts, relationships, properties, entities in invisible ranges, are described in mathematical representations such as formula, numbers, symbols, and graphs. Although the mathematical representation is an essential tool to better understand scientific phenomena, the mathematical element is pointed out as a reason for learning difficulty and losing interests in science. In order to further investigate the relationship between mathematics knowledge and science understanding, the current study examined 793 high school students' understanding of the pH value. As a measure of the molar concentration of hydrogen ions in the solution, the pH value is an appropriate example to explore what a student mathematical structure of logarithm is and how they interpret the proportional relationship of numbers for scientific explanation. To the end, students were asked to write their responses on a questionnaire that is composed of nine content domain questions and four affective domain questions. Data analysis of this study provides information for the relationship between student understanding of the pH value and related mathematics knowledge.

• YAKHAK HOEJI
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• v.22 no.4
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• pp.201-206
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• 1978

The analysis of elemental sulfur by polarography has already been reported in the literature. Only a discussion of the more important factors influencing the analysis is here presented. (1) The effects of pH on the reduction of elemental sulfur are pronounced and the use of buffered solutions for the analysis of elemental sulfur is necessary. The authors found that a pH of 4-6 was found to be reproducible polarograms by use of D.C. polarograph. However, in alkali solvents the plateau of elemental sulfur has a pronounced dip if the concentration of sulfur is as much as 30ppm. (2) A.C. polarographic method shows a very high sensitivity in the case of sulfur reduction, so that the very low concentration of sulfur can easily be determined (about 1ppm). (3) The characteristics of sulfur wave can be formulated according to Stackelberg-Hauck-Hans equation. It was found that the curve of the peak potential of elemental sulfur in A.C. polarography versus logarithm of sulfur concentration was obtained to be straight line with the slope of 29.6 millivolts. This result was well agreed with theoretical consideration. (4) It was assumed that this polarographical methods were applicable to micro-analysis of elemental sulfur in crude oil and its petrochemical products, precipitated sulfur, and sulfur ointments with accuracy and rapidity.

• The Korean Journal of Ecology
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• v.5 no.4
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• pp.143-153
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• 1982

Distributional pattern of vascular plant species in terms of species-area relationship and distances from their species pool on the 53 islands selected in the South Korea were studied. From the relationship between vascular plant species and area the equation of species-area was established as the follow: S=cA2 c=135.52 z=0.226 S; number of species A; area of island In the equation the Z value 0.226 is lower than those of any other localities reported in the world. Z value increased with the increasing distance from the species pool while C value decreased. The relationships of Z and/or C and distance from species pool, D, were established; Z=0.002D+0.176 C=-39.5logD+178.5 The tendency of common species decrease of them with the increasing islands was fifted to the Fisher's logarithm series. Common species 50% above was 39 species, including the most common species, Pinus thunbergii. Quotient of Similarity value by Sorensen (1948) on common species was relatively low i.e. 0.27∼0.47. It is noticeable for their vegetation conditions that the naturalized plant as a indicator of disturbance, for example Erigeron canadensis, was widely distributed.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1726-1728
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• 2003

The aging diagnosis method using partial discharge measurement detects discharge signals that critical cause of failure in insulation material operated a long time and can diagnose aging state of insulation materials with an aging analysis algorithm. The HFPD measurement method is a technique to analyze aging state of high voltage insulation materials and detect higher frequency signals than conventional PD measurement method therefore it takes less noise effect and could execute active line measurement. It is possible to analyze main discharge phenomena and obtain access to aging progress occurred in insulation materials through accumulation of HFPD signals during determined interval and expression of fractal dimension using statistical process of accumulated signals. The HFPD signals that occurred in each applied voltages are measured during 180 cycles and accumulated to the same phase of one cycle. These patterns that made by previous method are normalized with logarithm function and than inputted to neural networks. The aging diagnosis of insulation material was possible and the recognition ratio of neural network appeared very high.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.4.1-4.6
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• 2011

Objectives: This study was carried out to determine whether or not pine needles can be used as passive samplers of atmospheric polycyclic aromatic hydrocarbons (PAHs) using the correlation between accumulated PAH concentrations in air (Ca, ng/$m^3$) and those deposited on pine needles (Cp, ng/g dry). Methods: PAHs in ambient air was collected using low volume PUF sampler and pine needles was gathered at same place for 7 months. Results: A good correlation ($R^2$=0.8582, p<0.05) was found between Ca and Cp for PAHs with a higher gaseous state in air (AcPy, Acp, Flu, Phen, Ant, Flt, Pyr, BaA and Chry), but there was a poorer correlation ($R^2$=0.1491, p=0.5123) for the PAHs with a lower gaseous state (BbF, BkF, BaP, DahA, BghiP and Ind123). A positive correlation ($R^2$=0.8542) was revealed between the logarithm of the octanol-air partitioning coefficient ($logK_{oa}$) and Cp/Ca for the PAHs with a higher gaseous state in air, but there was a negative correlation ($R^2$=0.8131) for the PAHs with a lower gaseous state. The Ca-Cp model could not be used to estimate PAHs concentrations in air using deposited PAHs concentrations on pine needles, but the logKoa-Cp/Ca model could be used. Conclusions: It was found that pine needles can be used as passive samplers of atmospheric PAHs.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.6
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• pp.19-26
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• 2010

Batch experiments were conducted to investigate growth and nutrient removal performance of microalgae Chlorella vulgaris by using piggery wastewater in different concentration of pollutants and the common growth models (logistic, Gompertz and Richards) were applied to compare microalgal growth parameters. Removal of nitrogen (N) and phosphorus (P) by Chlorella vulgaris showed correlation with biomass increase, implying nutrient uptake coupled with microalgae growth. The higher the levels of suspended solids (SS), COD and ammonia nitrogen were in the wastewater, the worse growth of Chlorella vulgaris was observed, showing the occurrence of growth inhibition in higher concentration of those pollutants. The growth parameters were estimated by non-linear regression of three growth curves for comparative analyses. Determination of growth parameters were more accurate with population as a variable than the logarithm of population in terms of R square. Richards model represented better fit comparing with logistic and Gompertz model. However, Richards model showed some complexity and sensitivity in calculation. In the cases tested, both logistic and Gompertz equation were proper to describe the growth of microalgae on piggery wastewater as well as easy to application.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.301-304
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• 2006

As is different from formerly used fixing camera method in this paper, proposed method that can measure the speed of vehicles and logarithm of vehicles in video. Vehicles that proposed method runs with 50km/h, 80km/h, 90km/h's the speed recording on Video Tape beginning point and time of reaching point draw, and calculated 47.57km/h, 81.20km/h, the 90.00km/h speed by time and distance, the tracking cars and the velocity detection in video with the 'begin-line mark' and the 'end-line mark' processing.