• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.326-331
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• 2015

High salinity and sodicity of soils play a negative role in producing crops in reclaimed tidal lands. To evaluate the effects of soil ameliorants on salt removal in a highly saline and sodic soil of reclaimed tidal land, we conducted a column experiment with treating gypsum, compost, and phosphate at 0-2 cm depth and measured the salt concentration of leachate and soil. Electrical conductivity of leachate was $45-48dSm^{-1}$ at 1 pore volume (PV) of water and decreased to less than $3dSm^{-1}$ at 3 PV of water. Gypsum significantly decreased SAR (sodium adsorption ratio) of leachate below 3 at 3 PV of water and soil ESP (exchangeable sodium percentage) below 3% for the whole profile of soil column. Compost significantly decreased ESP of soil at 0-5 cm depth to 5% compared with the control (20%). However, compost affected little the composition of cations below a depth of 5 cm and in leachate compared with control treatment. It was concluded that gypsum was effective in ameliorating reclaimed tidal lands at and below a soil layer receiving gypsum while compost worked only at a soil layer where compost was treated.

• Journal of the Korean institute of surface engineering
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• v.52 no.1
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• pp.30-36
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• 2019

In this study, we investigated the effects of anodizing time, dyeing treatment time, and variations in coloring concentration on the color of an AA5052 alloy processed by dye-treated anodizing. The outward color of the anodized film changed to deep red according to increases in anodizing time, dyeing treatment time, and coloring concentration; accordingly, lightness $L^*$ decreased and saturation $a^*$ and $b^*$ increased. The concentration of the dye and the UV-visible absorbance showed a nearly perfect linear relationship, allowing a quantitative analysis of the absorbed dye. Because the quantity of absorbed dye increased as anodizing time, dyeing treatment time, and coloring concentration increased, the outward color of the anodized film deepened. In addition, from the GD-OES depth profile, we found that the dye was preferentially absorbed on the surface of the porous anodized film.

• Korean Journal of Environmental Biology
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• v.18 no.3
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• pp.299-305
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• 2000

To determine the effects of underlayer vegetation on soil properties, the profiles, physical, and chemical properties of soil were investigated upon Fagus multinervis -Rumohra standishii, Fagus multinervis - typical, and Fagus multinervis -Sasa kurilensis subcommunities that was growing at Songinbong area of Ullungdo. There were little differences in soil profile properties among the three subcommunities. Also, there were little differences in physical and chemical properties of soil among the three subcommunities, except exchangeable Ca concentration in 0-10 cm soil depth. However, the soils of the study area in 0-10 cm soil depth comprised high organic matter and total N concentration as in an average value of 21.6% and 0.74%, respectively. Also, the soil showed very low bulk density and pH as in an average value of 0.43 g/㎤ and 4.4 in 0-10 cm soil depth, respectively. Due to the high soil organic matter and total N concentrations and the low bulk density and pH, the soil properties of Songinbong area are different from those of other forest in Korea.

• Journal of Ecology and Environment
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• v.41 no.9
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• pp.271-280
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• 2017

Background: Soil microorganisms play key roles in nutrient cycling and are distributed throughout the soil profile. Currently, there is little information about the characteristics of the microbial communities along the soil depth because most studies focus on microorganisms inhabiting the soil surface. To better understand the functions and composition of microbial communities and the biogeochemical factors that shape them at different soil depths, we analyzed microbial activities and bacterial and fungal community composition in soils up to a 120 cm depth at a fallow field located in central Korea. To examine the vertical difference of microbial activities and community composition, ${\beta}$-1,4-glucosidase, cellobiohydrolase, ${\beta}$-1,4-xylosidase, ${\beta}$-1,4-N-acetylglucosaminidase, and acid phosphatase activities were analyzed and barcoded pyrosequencing of 16S rRNA genes (bacteria) and internal transcribed spacer region (fungi) was conducted. Results: The activity of all the soil enzymes analyzed, along with soil C concentration, declined with soil depth. For example, acid phosphatase activity was $125.9({\pm}5.7({\pm}1SE))$, $30.9({\pm}0.9)$, $15.7({\pm}0.6)$, $6.7({\pm}0.9)$, and $3.3({\pm}0.3)nmol\;g^{-1}\;h^{-1}$ at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively. Among the bacterial groups, the abundance of Proteobacteria (38.5, 23.2, 23.3, 26.1, and 17.5% at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively) and Firmicutes (12.8, 11.3, 8.6, 4.3, and 0.4% at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively) decreased with soil depth. On the other hand, the abundance of Ascomycota (51.2, 48.6, 65.7, 46.1, and 45.7% at 15, 30, 60, 90, and 120 cm depths, respectively), a dominant fungal group at this site, showed no clear trend along the soil profile. Conclusions: Our results show that soil C availability can determine soil enzyme activity at different soil depths and that bacterial communities have a clear trend along the soil depth at this study site. These metagenomics studies, along with other studies on microbial functions, are expected to enhance our understanding on the complexity of soil microbial communities and their relationship with biogeochemical factors.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.11
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• pp.1286-1293
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• 1988

A general closed form expression for the channel length of the self-aligned double-diffused MOS transistor is obtained from the 2-dimensional Gaussian doping profile. The proposed model in this paper is composed of the doping concentration of the substrate, the final surface doping concentration and the vertical junction depth of the each double-diffused region. The calculated channel length is in good agreement with the experimental results. Also, the optimum channel structure for the prevention of the channel puncthrough is obtained by the averaged doping concentration in the channel region. A correspondence between the results of device simulation of channel punchthrough and the estimations of simplified model is confirmed.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.12
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• pp.46-53
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• 1997

The TMA gas sensors are fabricated with the ZnO-based thin films grown by a RF magnetron sputtering method. The hall effect measurement and AES analysis are carried out to investigate the effects of the sputtering gases and dopants which effect on the electrical resistivity and sensitivity to TMA gas. We measure the cfhanges of the surface carrier concentration, haall electron mobility, electrical resistivity, surface condition, and depth profile of the films. The ZnO-based thin film sensors sputtered in oxygen, or added with dopants showed a high sruface carrier concentration, film sensors sputtered in oxygen and doped with 4.0 wt.% $Al_{2}$O$_{3}$, 1.0 wt.% TiO$_{2}$, and 0.2 wt% v$_{2}$O$_{5}$ showed the highest surface carrier concentration of 5.952 * 10$^{20}$ cm$^{-3}$ , hall electron mobility of 176.7 cm$^{2}$/V.s, lowest electrical resistivity of 6*10$^{-5}$ .ohm.cm and highest sensitivity of 12. These results were measured at a working temperature of 300.deg. C to 8 ppm TMA gas.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.429-447
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• 1995

This study was designed to determine the most effective concentration of fluoride and levels of laser irradiation for the remineralization of decayed teeth. After irradiation with a pulsed Nd:YAG laser and the topical application of fluoride, phosphate and fluoride concentration in enamel were measured. And then the changes on surface enamel using an scanning electron microscope were observed. Samples by extraction healthy, permanent, mandibular bovine teeth with no caries were obtained. Among them 371 healthy samples were selected and artificial carious lesions were made. 20 samples were assigned to each experimental group. After irradiation with a pulsed Nd:YAG laser with total energy densities of 10J/$\textrm{cm}^2$, 20J/$\textrm{cm}^2$ for each group. On the teeth, 2% NaF, 1.9% NH4F, 1.6% TiF4 Elmex gel(amine fluoride) and 1.23% APF gel were applied. After pH circulatory procedures, concentrations of fluoride with and Ionalyzer (Orion Research, Model 901, USA) and phosphates with an Uv/V is spectrophotometer (Uvikon 860, Kontrom Co, Switzerland) were measured. By etching the teeth in layers and measuring fluoride concentrations, a profile of fluoride penetration according to depth could be developed. And also the changes on the surface of the enamel using an electron scanning microscope were observed. The comparative analysis yielded the following results : 1. Phosphate concentration was low in all groups compared with the control group except for teeth treated Elmex gel, irradiated with 10J/$\textrm{cm}^2$ and 30J/$\textrm{cm}^2$ energy densities. Teeth treated with APF gel and 30J/$\textrm{cm}^2$ irradiation gad the lowest phosphate concentration. 2. Among all groups, fluoride concentrations in tooth enamel were highest in APF gel and NaF groups irradiated at 30J/$\textrm{cm}^2$. The APF gel group had the highest fluoride concentrations across all energy densities. 3. In the APF gel group, and the NaF group, the greater the energy density of the laser, the higher the fluoride concentrations in the enamel. 4. In all groups, the concentration of fluoride in the enamel by depth tended to decrease with depth. 5. Under the scanning electron microscope, under the condition of irradiation with 20J/$\textrm{cm}^2$, enamel crack was detected for the first time. In the NH4F group, spherical deposits were found on the surface of the enamel, and in the TiF4 group the surface of enamel was covered with an irregular, thin membranous mass in places. In the APF gel and NaF groups irradiated with 10J/$\textrm{cm}^2$, spherical and irregular particles covered the teeth. When these groups were irradiated at 20J/cm2, they were covered with amorphous crystals. These results suggest that one could obtain more effective anticariogenic effects without damage to teeth when less than 20J/$\textrm{cm}^2$ energy densities and APF gel are used.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.1
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• pp.7-11
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• 2020

Carbon solubility on the paste deposition methods in the carbon-doped TiZrN coating was investigated in terms of lattice distortion and atomic concentration. After depositing the carbon paste by the dip coating, spin coating and screen printing, the laser was ablated to form the carbon gradient layer. Thickness and the concentration of doped carbon depended on the paste deposition method. Crystal structure analysis indicated that more lattice distortion occurred when coating layers were doped with spin coating and screen printing than when coating layers were doped with dip coating. The XPS depth profile showed that the thickness of carbon gradient layer by dip coating was about 30 nm, spin coating and screen printing are approximately 100 nm, formed more gradient layer. The hardness before laser carburization was about 30 GPa, and the hardness of 31 GPa with dip coating and 37 GPa with spin coating and screen printing. It was indicated that paste deposition methods for laser carburization contributed to lattice distortion and gradient layer.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.3
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• pp.219-224
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• 1996

Silage comkv, suwwn 19). sorghum $\times$ sudangrass(p. 988) and winter ryeNaton) were cultivated on imperfectly drained paddy field under two different draining methods, subsurface darinage by PVC pipes and open ditsched surface drainage. The crops were harvested at the stage of hard dough for corn and soft dough for wrghum and rye. The soil physical properties. soil colors. soil structure and soil wetness were improved in the subsurface drainage. Gravitational water table occured depth in 110 cm(dry season)~75cm(rain season). In soil profile description, yellowish brown with yellowish red mottles and well developed granular structure were found in the surface A horizon. The portion of solid phase in subsoils(B horizon) was reduced from 48.6%(undrained) to 43.7 %. A blocky structure with dark gray to gray were described in the open ditsched surface drainage. Severe wet depression of the crops was observed due to it's higher moisture contents, where the gravitational water occured depth in 25~37cm during the rainy season. The chemical properties of paddy soils were less affected by drainage methods. The concentration of available phosphate. organic matter and exchangeable K, Ca and Mg were decreased in the subsurface drained soils. The annual dry matter yields of com-rye cropping were 17.8 ton in the undrained, 21.6 ton in the open ditsch drainage and 35.9 ton/ha in the subsurface drainage.

• Korean Journal of Optics and Photonics
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• v.17 no.5
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• pp.437-446
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• 2006

A fabrication method fur high-aspect-ratio microchannels in stainless steel using laser-assisted thermochemical wet etching is reported in this paper. The fabrication of deep microchannels with an aspect ratio over ten is realized by applying a multiple etching process with an optimization of process conditions. The cross-sectional profile of the microchannels can be adjusted between rectangular and triangular shapes by properly controlling laser power and etchant concentration. Excellent dimensional uniformity is achieved among the channels with little heat-affected area. Microchannels with a width ranging from 15 to $50{\mu}m$ can be fabricated with an aspect ratio of ten and a pitch of 150 m or smaller. The effects of process variables such as laser power, scan speed, and etchant concentration on the fabrication results, including etch width, depth, and cross-sectional profile are closely examined.