• Korean Journal of Materials Research
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• v.32 no.2
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• pp.107-113
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• 2022

Fibrous supercapacitors (FSs), owing to their high power density, good safety characteristic, and high flexibility, have recently been in the spotlight as energy storage devices for wearable electronics. However, despite these advantages, FCs face many challenges related to their active material of carbon fiber (CF). CF has low surface area and poor wettability between electrode and electrolyte, which result in low capacitance and poor long-term stability at high current densities. To overcome these limits, fibrous supercapacitors made using surface-activated CF (FS-SACF) are here suggested; these materials have improved specific surface area and better wettability, obtained by introducing porous structure and oxygen-containing functional groups on the CF surface, respectively, through surface engineering. The FS-SACF shows an improved ion diffusion coefficient and better electrochemical performance, including high specific capacity of 223.6 mF cm^-2 at current density of 10 ㎂ cm^-2, high-rate performance of 171.2 mF cm^-2 at current density of 50.0 ㎂ cm^-2, and remarkable, ultrafast cycling stability (96.2 % after 1,000 cycles at current density of 250.0 ㎂ cm^-2). The excellent electrochemical performance is definitely due to the effects of surface functionalization on CF, leading to improved specific surface area and superior ion diffusion capability.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.4
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• pp.215-222
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• 2023

3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals, 3Y-TZP) ceramics are emerging as dental implant materials due to their superior optical and mechanical properties as well as excellent biophysical properties, in spite of low bioactivity. In this study, we investigated to sintered properties and microstructural defects of dental zirconia implants fabricated by ceramic injection molding and post-HIP (Hot isostatic pressing) processing and analyzed the processing parameters related with the obtainment of its high sinterd density. Sintered and microstructural parameters, i.e, apparent density, grain size and phase composition of zirconia implants fabricated by injection molding were dependent on the fixtute size and implant type. Maximum sintered density of 99.2% and minimum grain size of 0.3-0.4 ㎛ were obtained from large-scaled 2-body sample. In 1-body ceramic implant, high sintered density of 99.5% was obtained, but it had a little monoclinic phase and wide grain size distribution.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.126-130
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• 1983

This study was desinged to find out the effects of soil physical properties on root development of barley. Barley fields were selected in consideration of drainage class and texture. Soil hardness were measured at the field. Soil bulk density, air ratio and root distribution were obtained from the core samples. 1. The amount of roots were increased and the root were distributed deeper layers with better drainage class and finer soil texture. 2. Soil hardness was related to soil bulk density, and the regression coefficient was increased with clay content (Clay ; $r=0.837^{**}$, Clay loam ; $r=0.678^*$, and Sandy loam ; $r=0.654^*$). 3. There was a highly negative correlation ($r=-0,846^{**}$) between bulk density of subsoils and amount of roots and the root developments were markedly reduced in soil bulk density of $1.4g/cm^3$. 4. Bulk density of subsoils was decreased with worse soil drainage and finer texture. Especially, in case of clayey soil at imperfectly or moderately drained soils, the air phase was less than 20% and the barley growth was worse. 5. Root development were related to hardness in surface, bulk density and ok phase in 10-30cm layer, and air phase in 30-50cm layer.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.185-191
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• 2001

The morphological variation and density of the Euglena viridis cells and environmental factors of urban waterways of Daejoncheon , Jeonjucheon, Kwangjucheon, Kumhogang, Mihocheon,and Musimcheon, Korea were studied from 25December, 1995 to 5 January, 1997 in order toelucidate possible relationships among the bio-logical and abiological factors. All E. viridis cells were same in having single star-cluster of chlo-roplast lobes and included two morphotypes based on other detailed morphology. The morphotype I cells agreed well with the typical form off. viridrs and commonly occurred in most of waters and bloomed with $5386\;cells\;{\cdot}\;mL^{-1}$ in Kwangjucheon. The density of the morphotype Ipositively correlated with ammonium (r = 0.80)and nitrite (r = 0.68), while negatively with nit-rate concentration. The morphotype II cells were characterized by having randomly scattered cytoplasmic granules beneath pellicle and unevenmargined lobes of chloroplasts. The density of the morphotype II positively correlated with nitrate (r = 0.98), while negatively correlated with ammonium and nitrite. However, the density of each morphotype was not significantly related with inorganic phosphate, temperature and pH of surface water. These results indicate that E. viridis includes two morphotypes in urban waterways in Korea, that coexist in the same period and station as a response of allocation of nitrogenous nutrients.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.1
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• pp.29-33
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• 2011

The current density in copper electroplating is directly related with the productivity and then to increase the productivity, the increase in current density is required. To obtain the high mass flow rate, rotating disk electrode(RDE) was employed. High rotational speed in RDE can increase the mass flow rate and then high speed electroplating was possible using RDE to control mass flow. Two types of cathode were used. One is RDE and another is rotating cylindrical electrode(RCE). A constant-current, constant-voltage and linear sweep voltammetry were applied to investigate current and voltage relationship. The maximum current density without evolution of hydrogen gas was increased with rotational speed. Over 400 rpm, maximum current density was higher than 1000 A/$m^2$. The diffusion coefficients of copper calculated from the slope of the plots are $5.5{\times}10^6\;cm^2\;s^{-1}$ at $25^{\circ}C$ and $10.5{\times}10^6\;cm^2\;s^{-1}$ at $62^{\circ}C$. The stable voltage without evolution of hydrogen gas was -0.05 V(vs Ag/AgCl). Additives were added to prevent dendritic growth on cathode deposits. The surface roughness was analyzed with UV-Vis Spectrophotometer. The reflectance of the copper surface over 600 nm was measured and was related with the surface roughness. As the surface roughness improved, the reflectance was also increased.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.483-492
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• 2008

The characteristics of joint system (joint orientation and density) were studied for Cretaceous sedimentary rocks in the Nakdong River mid-basin (Haman-Gun, Changnyeong-Gun, and Uiryeong-Gun areas), and were related with faults, river system, and groundwater usage in the study area. The joint system was classified into JI ($N90^{\circ}-110^{\circ}E$), J2 ($N0^{\circ}-35^{\circ}E$), and J3 ($(N0^{\circ}-35^{\circ}W$), and was dominant along N-S and E-W directions. The N-S trending joint system is dominant in Haman Formation in the eastern and western parts of the study area, while the E-W trending joint system is prevalent in Chilgok Formation in the central part. The joint system may be associated with the faults located in the eastern and western parts in the study area which are elongated to NNE-SSW direction. Additionally, the joint density is higher along the Nakdong River, indicating close relationship between E-W trending joints and the river. Daily groundwater discharge versus joint density shows weak positive relationship, and specific capacity versus joint density appears negatively related. This indicates that groundwater occurrence does not greatly rely on joint density.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.99-104
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• 2003

TiN coated films show a good mechanical properties, high thermal properties and wear, erosion and corrosion resistance and are widely used as a coating materials in tools, ornaments, parts and semiconductors. In spite of these good properties, the fracture of TiN coated films occur during use. The fracture of TiN thin films is related to their microstructure. Especially, the life of TiN coated layer is related to the texture of the TiN films. One researcher suggested that the corrosion and erosion resistance of the TiN thin films is related to a uniform and dense structure of films. In this study, we studied the relationships between textures and friction coefficient, erosion and corrosion in TiN coated films. The flatness of (115) texture surface of TiN thin films is flatter than that of (111) texture surface. The friction coefficient of (115) texture surface of TiN thin films is similar with that of (111) texture surface. The wear resistance of (115) texture surface of TiN thin films is better than that of (111) texture surface. The erosion and corrosion resistance of (115) texture surface of TiN thin films is better than that of (111) torture surface. As well as texture, the wear, erosion and corrosion of TiN thin films has to consider defects such as pinholes, cracks, surface roughness and open columnar structure. The life of TiN coated products is influenced by the properties of wear, erosion, and corrosion resistance of TiN thin films and is related to texture of TiN coated films, density of pinholes and cracks, density of structure, and surface flatness.

• Journal of Preventive Medicine and Public Health
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• v.44 no.5
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• pp.218-225
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• 2011

Objectives: This study investigated the relationship between the blood mercury concentration and cardiovascular risk factors in elderly Korean individuals living in coastal areas. Methods: The sample consisted of 477 adults (164 males, 313 females) aged 40 to 65 years who visited a Busan health promotion center from June to September in 2009. The relationship between blood mercury concentration and cardiovascular risk factors including metabolic syndrome, cholesterol profiles, blood pressure, body mass index (BMI), waist circumference and waist-to-hip ratio (WHR), was investigated. Variables related to blood mercury concentration were further evaluated using multiple regression analysis. Results: The blood mercury concentration of the study population was 7.99 (range, 7.60 to 8.40) ${\mu}g$/L. In males, the blood mercury concentration was 9.74 (8.92 to 10.63) ${\mu}g$/L, which was significantly higher than that in females (7.21, [6.80 to 7.64] ${\mu}g$/L). The blood mercury concentration of the study population was related to several cardiovascular risk factors including low-density lipoprotein (LDL) cholesterol (p=0.044), high-density lipoprotein (HDL) cholesterol (p=0.034), BMI (p = 0.006), waist circumference (p = 0.031), and WHR (p < 0.001). In males, the blood mercury concentration was significantly correlated with WHR in the multiple regression analysis. Conclusions: In males, the blood mercury concentration was related to waist-to-hip ratio, which is a central obesity index and cardiovascular risk factor. Our finding suggests that cardiovascular disease risk in males was increased by mercury exposure via an obesity-related mechanism.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.5 s.153
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• pp.699-710
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• 2006

The objective of this study was to identify the texture-related components of woven fabrics and to develop a multidimensional perceptual structure map to represent the tactile textures. Eighty subjects in clothing and tektite industries were selected for multivariate data on each fabric of 30 using the questionnaire with 9 pointed semantic differential scales of 20 texture-related adjectives. Data were analyzed by factor analysis, hierarchical cluster analysis, and multidimensional scaling(MDS) using SPSS statistical package. The results showed that the five factors were selected and composed of density/warmth-coolness, stiffness, extensibility, drapeability, and surface/slipperiness. As a result of hierarchical cluster analysis, 30 fabrics were grouped by four clusters; each cluster was named with density/warmth-coolness, surface/slipperiness, stiffness, and extensibility, respectively. By MDS, three dimensions of tactile texture were obtained and a 3-dimensional perceptual structure map was suggested. The three dimensions were named as surface/slipperiness, extensibility, and stiffness. We proposed a positioning perceptual map of fabrics related to texture naming system(TNS). To classify the textural features of the woven fabrics, hierarchical cluster analysis containing all the data variations, even though it includes the errors, may be more desirable than texture-related multidimensional data analysis based on factor loading values in respect of the effective variables reduction without losing the critical variations.

• Journal of Nutrition and Health
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• v.39 no.2
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• pp.171-183
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• 2006

This study was conducted to examine dietary factors affecting bone status in the rural aged men. Quantitative ultrasound measurements (QUS) of bone, that may reflect certain architectural aspects of bone, have been shown to be associated with bone mineral density and fracture. Information of diet and anthropometry was collected in 164 aged men. Dietary intake data were obtained by 24-hour recall method. Measurements of the speed of sound (SOS, m/s), at distal radius, mid-tibia, phalanx, were performed using Omnisense 7000S analyzer (Sunlight Ltd., Tel Aviv, Israel). T-scores for bone SOS measurements at distal radius, mid-tibia and phalanx were 0.60, 0.03 and -0.42 respectively. The prevalence of osteopenia by use of the WHO criteria was 17.7% at the mid-tibia and 25.3% of the subjects at the distal radius. Age were negative association with bone SOS at three sites. Osteopenia group of radius were significantly lower in total foods and vegetable intakes than normal group. After adjusted for age, vegetable intakes were significantly and positively related to bone SOS at the radius. The bone SOS of the tibia were significantly and positively related to vegetable protein, iron, folate and vegetable intakes, but negatively related to fat intakes. Multiple regression analysis showed that bone SOS of tibia was positively associated with folate intakes. Vegetable intakes were positively associated with the bone SOS at three sites. These results indicate that the consumption of vegetables, sources of folate, may have a effect on bone status of men.