• The Journal of Engineering Geology
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• v.28 no.3
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• pp.501-512
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• 2018

The acid leachate derived from the sulfide mineral such as pyrite can cause problems such as aging of infrastructure and environment contamination around the civil construction site. The purpose of this study is to assess the environmental effect of an acid leachate derived from pyrite in the Miryang area under road construction. In this study, 13 samples of situ core were used for the net acid generation (NAG) experiment. The chemical composition including pH, oxidation and reduction potential (ORP) and electrical conductance of water samples produced from the NAG test was analyzed. In additional, five polished thin sections of rock cores were made for electro microprobe analyses. In the results of the NAG tests, 7 samples showed lower values than pH 3.5. It strongly indicated that these areas are under the environmental and infrastructure damage by the acid leachate. The chemical type of the 7 samples was classified as the $Fe(Ca)-SO_4$ type, which is totally a different type compared to general groundwater. The concentration of total sulfur ranges from 0.004% to 12.5%. 6 rock samples are plotted on a potentially acid forming zone in the relation diagram between the total sulfide and NAG-pH. In conclusion, it is suggested that a protection method against an environmental demage and an infrastructure corrosions by the acid leachate should be prepared in all of areas under a road construction.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.124-133
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• 2015

Electro interstitial scan shows potential as a non-invasive screening method. It can discriminate some diseases based on electric current response to induce low intensity direct current to limbs or local area of body. DDFAO was invented in France and it is claimed that multi-channel EIS(Electro Interstitial Scan) is useful for various diseases, especially, diagnoses of endocrine system such as diabetics are very effective. In this study, we verified the repeatability and sensitivity of DDFAO by using a RC phantom model and its clinical usefulness using data obtained from normal and diabetes subject groups. As a result, it showed the repeatability and the output change according to change of phantom characteristic, but it was hard to distinguish normal and patient groups non-invasively with just six surface electrodes of DDFAO. The repeatability and the clinical accuracy was not sufficient for screening or diagnostic purposes, as well. In spite of the results with low repeatability and accuracy conducted in this study, we still need further investigations to improve the EIS-based measurement method; EIS is very convenient and simple and it shows potential as a screening tool of the whole body health conditions rather than localized disease diagnosis.

• The Journal of Korean Medicine
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• v.31 no.5
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• pp.136-145
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• 2010

Objectives: Electroacupuncture according to Voll (EAV) has been used to quantify the skin's electrical resistance and conductance over acupuncture points that, based on traditional Chinese medicine, represent the state of health or disease of the organ or tissue. However, it doesn't have enough objective data yet, so the purpose of this study was to aid in the use of EAV in analysis of cerebrovascular disease risk factors. Methods: This study researched the clinical statistics of 216 cases: cerebrovascular attack (CVA) group 43, control group 173. We measured control meridian points (CMP) on hands and feet and the cardio ankle vascular index (CAVI) which represents atherosclerosis severity, and sex, age, hypertension, diabetes, dyslipidemia, and obesity. The data were then analyzed by t-test, chi-square test and logistic regression. Results: Between the CVA and control groups, there were not statistically significant differences in CMP. However, logistic regression analysis of the presence of CVA, mean of CMP heart and lung, sex, age, DBP (diastolic blood pressure), and HDL (high density lipoprotein) cholesterol showed that the risk of CVA was 1.1 times increased with CMP heart (p=0.002), in men was 4.12 times higher than in women (p=0.001), 1.09 times higher with age (p=0.000), 1.04 times higher with DBP (p=0.045), while was lower by 0.924 times with CMP lung (p=0.005) and 0.957 times with HDL cholesterol (p=0.006). Conclusion: Although there were not clear evidence or mechanisms about EAV, this study showed that if we study EAV further, we may be able to apply EAV as an objective instrument of oriental medicine in cerebrovascular disease.

• Journal of the Korean Chemical Society
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• v.38 no.8
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• pp.539-546
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• 1994

The critical micelle concentration(CMC) and the counterion binding $constant(\beta)$ at the CMC of cetyltrimethylammonium bromide(CTAB) in a series of aqueous solutions containing medium chain-length n-alcohols(Propanol, Butanol, Pentanol and Hexanol) have been determined from the concentration dependence of electrical conductance at serveral temperature from $17^{\circ}C\;to\;41^{\circ}C.$ Thermodynamic parameters $({\Delta}G^o_m,\;{\Delta}H^o_m,\;{\Delta}S^o_m,\;and\;{\Delta}C_p)$ associated with micelle formation of CTAB have been also estimated from the temperature dependence of CMC and $\beta$ values, and the significance of these parameters and their relation to the theory of micelle formation have been considered. The results show that an enthalpy-entropy compensation effect is usually observed for the micellization of CTAB. The effects of n-alcohols on the micellar properties (CMC and $\beta$) of CTAB solutions have been also investigated. The addition of n-alcohol to the CTAB solution in a small quantity decreases the CMC value and the counterion binding constant $(\beta)$ at the CMC, but the addition of n-alcohol in an excessive quantity increases the CMC values on the conterary. These results have been explained in terms of the effect of the micelle-solubilized alcohol on the micellar surface charge density.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.9
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• pp.815-820
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• 2016

An elastic polymer (e.g., PDMS) blended with EFG particles is a promising conductive composite for fabricating soft sensors that can detect an object's deformation up to or more than 50%. Here, we develop large-strain, sprayable soft sensors using a mixture of PDMS and EFG particles, which are used as a host elastomer and electrically conductive particles, respectively. A solution for a conductive composite mixture is prepared by the microwave-assisted graphite exfoliation, followed by ultrasonication-induced fragmentation of the exfoliated graphite and ultrasonic blending of PDMS and EFG. Using the prepared solutions for composite and pure PDMS, 1-, 2-, and 3-axis soft sensors are fabricated by airbrush stencil technique where composite mixture and pure PDMS are materials for sensing and insulating layers, respectively. We characterize the soft strain sensors after investigating the effect of PDMS/EFG wt% on mechanical compliance and electrical conductance of the conductive composite.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.100-109
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• 2002

Significant damage to concrete results from the intrusion of corrosive solutions, for example, dissolved chlorides corrode reinforcing steel and cause spatting. Effectively blocks the penetration of these solutions will eliminate or greatly reduce this damage and lead to increased durability. This study is to investigate the effects of pozzolanic admixtures, fly ash and silica fume, and a blast furnace slag on the chloride ion penetration of concretes. The main experimental variables wore the water-cementitious material ratios, the types and amount of admixtures, and the curing time. And it is tested for the porosity and pore size distributions of cement paste, chloride ion permeability based on electrical conductance, and 180-day ponding test for chloride intrusion. The results show that the resistance of concrete to the penetration of chloride ions increases as the w/c was decreased, and the increasing of curing time. Also, concrete with pozzolans exhibited higher resistance to chloride ion penetration than the plain concrete. The significant reduction in chloride ion permeability(charge passed) of concrete with pozzolans due to formation of a discontinuous macro-pore system which inhibits flow. It is shown that there is a relationship between chloride ion permeability and depth of chloride ion penetration of concrete, based on the pore structure (porosity and pore size distributions) of cement paste.

• Korean Journal of Environment and Ecology
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• v.27 no.6
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• pp.718-732
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• 2013

The purpose of this study was to provide data for the basic research to found the effective conservation and management plan for the Geumdangsil Pine Forest of Yecheon designated as Natural Monument No. 469. Furthermore, this paper suggest efficient sustainable forest preservation and using. In order to achieve the sustainable forest preservation, this study was to analyse topography, land use, tree growth, soil environment, forest usage and forest management, etc. According to analysis the results, the site area is located in the flatlands where is from 130 to 140 m above sea level. The around forest was transformed into agricultural land. The 565 individuals of Pinus densiflora grows in the forest, whereas, 25 trees was cut down or died. There are signs of 25 stumps. The most of 565 trees' diameter at breast height(DBH) was centerized between 30 cm and 50 cm, moreover, the average life expectancy of trees were 85.4 years. The oldest age of tree was estimated to be 200 years. The Sample trees of rate of branch growth is from 4.3 cm to 5.1 cm per year. The middle branch which is more vigorous growth grow 24.2 cm for 3 years. Moreover, the result of soil physico-chemical properties analysis of 7 plots, 4 categories which is soil organic matter, total nitrogen, available phosphoric acid, specific electrical conductance was generally good, however, the 2 categories which is soil pH, exchangeable cation needed improvement. Currently, the site was not pressured by facilities and usage, however, there might be threaten by agriculture such as encroaching on forest. Therefore, there should establish comprehensive ecosystem management such as facility management, visitors management and operation management In this paper considered 4 fields that is ecosystem management, facility management, visitors management and operation management for sustainable management.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.411-427
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• 2006

This study aimed to recognize characteristics of groundwater flow in fractured bedrocks based on zonal pump-ing tests, slug tests, water quality logs and borehole TV camera logs conducted on two boreholes (NJ-11 and SJ-8) in the city of Naju. Especially, the zonal pumping tests using sin91e Packer were executed to reveal groundwater flow characteristics in the fractured bedrocks with depth. On borehole NJ-11, the zonal pumping tests resulted in a flow dimension of 1.6 with a packer depth of 56.9 meters. It also resulted in lower flow dimensions as moving to shallower packer depths, reaching a flow dimension of 1 at a 24 meter packer depth. This fact indicates that uniform permissive fractures take place in deeper zones at the borehole. On borehole SJ-8, a flow dimension of 1.7 was determined at the deepest packer level (50 m). Next, a dimension of 1.8 was obtained at 32 meters of packer depth, and lastly a dimension of 1.4 at 19 meters of packer depth. The variation of flow dimension with different packer depths is interpreted by the variability of permissive fractures with depth. Zonal pumping tests led to the utilization of the Moench (1984) dual-porosity model because hydraulic characteristics in the test holes were most suitable to the fractured bedrocks. Water quality logs displayed a tendency to increase geothermal temperature, to increase pH and to decrease dissolved oxygen. In addition, there was an increasing tendency towards electrical conductance and a decreasing tendency towards dissolved oxygen at most fracture zones.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.1-9
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• 2021

This study was conducted to examine the changes of photosynthesis, growth, chlorophyll contents and functional material contents in light intensity and EC concentration of wild baby leaf vegetable, Indian lettuce (Lactuca indica L. cv. 'Sunhyang') in DFT hydroponics. The cultivation environment was 25±1℃ of temperature and 60±5% of relative humidity in growth system. At 14 days after sowing, combination effect of light intensity (Photosynthetic Photon Flux Density (PPFD 100, 250, 500 µmol·m-2·s-1) and EC level (EC 0.8, 1.4, 2.0 dS·m-1) of nutrient solution was determined at the baby leaf stage. The photosynthesis rate, stomatal conductance, transpiration rate and water use efficiency of Indian lettuce increased as the light intensity increased. The photosynthesis rate and water use efficiency were highest in PPFD 500-EC 1.4 and PPFD 500-EC 2.0 treatment. The chlorophyll content decreased as the light intensity increased, but chlorophyll a/b ratio increased. Leaf water content and specific leaf area decreased as light intensity increased and a negative correlation (p < 0.001) was recognized. Plant height was the longest in PPFD 100-EC 0.8 and leaf number, fresh weight and dry weight were the highest in PPFD 500-EC 2.0. Anthocyanin and total phenolic compounds were the highest in PPFD 500-EC 1.4 and 2.0 treatment, and antioxidant scavenging ability (DPPH) was high in PPFD 250 and 500 treatments. Considering the growth and functional material contents, the proper light intensity and EC level for hydroponic cultivation of Indian lettuce is PPFD 500-EC 2.0, and PPFD 100 and 250, which are low light conditions, EC 0.8 is suitable for growth.