• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.2
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• pp.17-24
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• 2002

This research was conducted to investigate the influences caused by solifluction soil on the physicochemistry of stream water quality at the riparian area four points in the northeastern part of the Bughansan National Park from March to May of 2001. The average pH of stream water was higher than those in the caused by solifluction soil. The average electrical conductivity of upstream water was about 0.8~1.7 times lower than those in the caused by solifluction soil, but the average electrical conductivity of downstream water was about 1.6~3.8 times higher than those in the caused by solifluction soil. Therefore, these results showed that the water quality of downstream was worse than that of upstream. Twelve factors including the physicochemistry on the stream water and caused by solifluction soil were analyzed by spss/pc+ for the data collected from during March to May of 2001. pH of stream water was very significantly correlated with pH and electrical conductivity at the caused by solifluction soil. And the electrical conductivity of stream water was very significantly correlated with electrical conductivity and the amount of cation($Na^+$, ${NH_4}^+$, $Mg^{2+}$) at the caused by solifluction soil.

• Journal of Environmental Science International
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• v.30 no.7
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• pp.519-527
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• 2021

Moving average precipitation provides periodic precipitation patterns by solving precipitation irregularities. However, due to uncertain moving average periods, excessive data smoothing occurs, which limit the possibility to analyze groundwater levels in the short term. Nonetheless, groundwater level fluctuation can compensate these limitations as it can calculate appropriately for unit time and verify the effect of precipitation penetrated into groundwater in a short time period. In this study, the characteristics of groundwater level were evaluated using groundwater level fluctuation to compensate for limitations of groundwater level analysis using moving average precipitation. In addition, the groundwater quality was investigated using the electrical conductivity fluctuation. The study site was Hyogyo-ri, Yesan-si, Chungcheongnam-do. Four observation wells and an automated weather system were used. The correlation between groundwater level fluctuation and precipitation (Case 1) and the correlation between groundwater level and moving average precipitation (Case 3) were compared. In the analysis for 1 hour data, the correlation coefficient of Case 1 was higher than that of Case 3, and in the analysis for 1 day data, the correlation coefficient of Case 3 was higher than that of Case 1.

• Electrical & Electronic Materials
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• v.10 no.8
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• pp.794-799
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• 1997

Poly-Si films have been prepared by solid phase crystallization of LPCVD(low-pressure CVD) amorphous silicon. The crystallinity of poly-Si films has been derived from UV reflectance spectrum and lies in the range between 70% and 80% . From XRD measurement the peak at 28.2$^{\circ}$from (111) plane is dominantly detected in the SPC poly-Si films, The average grain size of poly-Si film is determined by the image of SEM and varies from 4000 $\AA$ to 8000$\AA$. The electrical conductivity of as-deposited amorphous silicon film is about 2.5$\times$10$^{-7}$ ($\Omega$.cm)$^{-1}$ , and 3~4$\times$10$^{-6}$ ($\Omega$.cm)$^{-1}$ of room temperature conductivity is the SPC poly-Si films. The conductivity activation energies are 0.5~0.6 eV or the 500$\AA$-thick poly-Si films.

• Journal of the Korean earth science society
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• v.43 no.4
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• pp.539-556
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• 2022

In the coastal areas of Jeju Island, composed of volcanic rocks, saltwater intrusion occurs due to excessive pumping and geological characteristics. Groundwater level and electrical conductivity (EC) in multi-depth monitoring wells in coastal areas were characterized from 2005 to 2019. During the period of the lowest monthly precipitation, from November 2017 until February 2018, groundwater level decreased by 0.32-0.91 m. During the period of the highest monthly precipitation, from September 2019 until October 2019, groundwater level increased by 0.46-2.95 m. Groundwater level fluctuation between the dry and wet seasons ranged from 0.79 to 3.73 m (average 1.82 m) in the eastern area, from 0.47 to 6.57 m (average 2.55 m) in the western area, from 0.77 to 8.59 m (average 3.53 m) in the southern area, and from 1.06 to 12.36 m (average 5.92 m) in the northern area. In 2013, when the area experienced decreased annual precipitation, at some monitoring wells in the western area, the groundwater level decreased due to excessive groundwater pumping and saltwater intrusion. Based on EC values of 10,000 ㎲/cm or more, saltwater intrusion from the coastline was 10.2 km in the eastern area, 4.1 km in the western area, 5.8 km in the southern area, and 5.7 km in the northern area. Autocorrelation analysis of groundwater level revealed that the arithmetic mean of delay time was 0.43 months in the eastern area, 0.87 months in the northern area, 10.93 months in the southern area, and 17.02 months in the western area. Although a few monitoring wells were strongly influenced by nearby pumping wells, the cross-correlation function of the groundwater level was the highest with precipitation in most wells. The seasonal autoregressive integrated moving average model indicated that the groundwater level will decrease in most wells in the western area and decrease or increase in different wells in the eastern area.

• Journal of Animal Science and Technology
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• v.51 no.4
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• pp.265-272
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• 2009

A total of 486 milk records were collected from 16 diary farms in Imsil-gun, Jeollabuk-do. Results obtained were as follows: The average 3MG (amount of milk within the first three minute) was 7.44 kg and 55% of total milk yield was produced within 3 min. The average of SPL (% of foam in milk) was 33.93% and the average of MNG (strip yield) was 0.14 kg, which was less than 1% of total milk yield. The averages of HMF (highest milk flow), HMG (maximum milk flow rate in one minute) and DMHG (average milk flow in the main milking phase) were 3.03 kg/min, 2.94 kg/min and 2.05 kg/min, respectively and the average milking speed in Imsil-gun was slower than other regions. The average of tS500(time to reach 0.5 kg/min at beginning) was 0.23min (about 14 seconds) and that of tMGG (duration of the total milking) was 7.75min. The average tMBG (duration of the dry milking phase) was 0.58 min (35 seconds) and that of tMNG (duration of the stripping phase) was 0.42min (14 seconds). The averages of ELHMF (electrical conductivity at highest milk flow) and ELAP (beginning peak level of the electrical conductivity) were 6.81 mS/cm and 7.58 mS/cm, respectively. The average of ELMAX (maximum electrical conductivity) was 7.48 mS/cm and that of ELAD (beginning peak difference of the electrical conductivity) was 0.61 mS/cm. While the total milk yields for DMHG, tMHG (duration of the main milking phase), tPL (duration of the plateau phase), tAB (duration of the descending phase) and tMGG were positively correlated (0.35~0.54), those for tMBG and SPL were negatively correlated (-0.11 and -0.27). As the DMHG increased, tMHG, tPL, tAB, tMGG and SPL decreased. While the cows with higher electrical conductivity at the beginning of milking had less somatic cell counts, cows with higher electrical conductivity after the peak of milk yield had more somatic cell counts. The results of this experiment indicated that through milking based on milking and lactating standards and the regular checking of milking status, the qualities of milk and milk yields could be improved.

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.403-407
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• 2022

This research investigated the effect of Si addition on the microstructure, mechanical properties, electric and thermal conductivity of as-extruded Al 6013 alloys. As the content of Si increased, the area fraction of the second phase increased. As the Si content increased, the average grain size decreased remarkably, from 182 (no Si addition) to 142 (1.5Si), 78 (3.0Si) and 77 ㎛ (4.5Si) due to dynamic recrystallization by the dispersed second particles in the aluminum matrix during the hot extrusion. As the Si content increased, the yield strength and ultimate tensile strength increased. The maximum values of yield strength and ultimate tensile strength were 224 MPa and 103 MPa for the 6013-4.5Si alloy. As the amount of Si added increased, the electrical and thermal conductivity decreased. The electrical and thermal conductivity of the Al6013-4.5Si alloy were 44.0 % IACS and 165.0 W/mK, respectively. The addition of Si to Al 6013 alloy had a significant effect on its thermal conductivity and mechanical properties.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.672-676
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• 2021

In this paper, the effect of Ni (0, 0.5 and 1.0 wt%) additions on the microstructure, mechanical properties and electrical conductivity of cast and extruded Al-MM-Sb alloy is studied using field emission scanning electron microscopy, and a universal tensile testing machine. Molten aluminum alloy is maintained at 750 ℃ and then poured into a mold at 200 ℃. Aluminum alloys are hot-extruded into a rod that is 12 mm in diameter with a reduction ratio of 39:1 at 550 ℃. The addition of Ni results in the formation of Al₁₁RE₃, AlSb and Al3Ni intermetallic compounds; the area fraction of these intermetallic compounds increases with increasing Ni contents. As the amount of Ni increases, the average grain sizes of the extruded Al alloy decrease to 1359, 536, and 153 ㎛, and the high-angle grain boundary fractions increase to 8, 20, and 34 %. As the Ni content increases from 0 to 1.0 wt%, the electrical conductivity is not significantly different, with values from 57.4 to 57.1 % IACS.

• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.16-22
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• 2017

An experiment was conducted to detect aquaculture pond bottom soil nutrients, pH and electrical conductivity with a view to optimize production and to incorporate the scientific method of fish nursing, rearing and culturing at Noakhali district in Bangladesh. The soil samples were collected from the recently dug ponds (1 - 5 years) and older ponds (> 5 years). Samples were taken from five different spots in a Z shape from each pond and were mixed to get a composite sample. The composite samples from the ponds were collected in polyethylene bags and shipped to the laboratory for analysis. The soil samples were analyzed with respect to pH, electrical conductivity (EC), organic carbon (OC), organic matter (OM), nitrogen (N), phosphorous (P), potassium (K) and sulfur (S). The average value of pH, OC, OM, N, P, K and S were $7.43{\pm}0.40$, $2.21{\pm}1.43%$, $1.47{\pm}0.53%$, $2.52{\pm}0.94{\mu}g\;g^{-1}$, $0.126{\pm}0.047{\mu}g\;g^{-1}$, $3.84{\pm}1.77{\mu}g\;g^{-1}$, $0.191{\pm}0.106{\mu}g\;g^{-1}$ and $306.72{\pm}222.05{\mu}g\;g^{-1}$ respectively, in Noakhali. The average EC, OC, OM, N and P contents were found to be higher in Subornachar than those in Sonapur. On the other hand pH, K and S were found to be higher in Sonapur than the values of Subornachar. The pH, EC, OC, OM, N and S contents were found to be higher in new ponds than old ponds whereas P and K contents were found to be higher in old pond than in new pond.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.3
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• pp.1327-1331
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• 2014

Background: Electrical impedance tomography (EIT) is a new non-invasive, mobile screening method which does not use ionizing radiation to the human breast; allows conducting quantitative assessment of the images besides the visual interpretation. The aim of this study was to correlate the quantitative assessment and visual interpretation of breast electrical impedance tomographs and associated factors. Materials and Methods: One hundred and fifty mammography patients above 40 years and undergoing EIT were chosen using convenient sampling. Visual interpretation of the images was carried out by a radiologist with minimum of three years experience using the breast imaging - electrical impedance (BI-EIM) classification for detection of abnormalities. A set of thirty blinded EIT images were reinterpreted to determine the intra-rater reliability using kappa. Quantitative assessment was by comparison of the breast average electric conductivity with the norm and correlations with visual interpretation of the images were determined using Chi-square. One-way ANOVA was used to compare the mean electrical conductivity between groups and t-test was used for comparisons with pre-existing Caucasians statistics. Independent t-tests were applied to compare the mean electrical conductivity of women with factors like exogenous hormone use and family history of breast cancer. Results: The mean electrical conductivity of Malaysian women was significantly lower than that of Caucasians (p<0.05). Quantitative assessment of electrical impedance tomography was significantly related with visual interpretation of images of the breast (p<0.05). Conclusions: Quantitative assessment of electrical impedance tomography images was significantly related with visual interpretation.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.3
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• pp.30-37
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• 2001

This study was conducted to investigate physicochemical property changes from July 1998 to August 2001 in Mt. Bukhansan National Park. Four water sampling points were selected to measure the quality of stream water in the northeastern part of the Mt. Bukhansan National Park. The results were summarized as follows; In spring, the average pH of stream water was below the first class of the river water quality standard, while it was normal level in summer. The average electrical conductivity was about 2.3~3.3 times higher in downstream water than in upstream water during spring and summer. The contents of anions($Cl^-$, $NO{_3}^-$, $SO{_4}^{2-}$) were about 1.1~7.4 and 0.4~11.4 times higher in downstream than in upstream water, respectively. These results indicate that water quality was poorer in downstream than in upstream water. We suggest that stream water in the Mt. Bukhansan National Park should be protected from impacts of snow melting mineral particles in spring season and human impacts like wastewater of point source in summer season.