• Journal of the Korea Computer Industry Society
• /
• v.8 no.2
• /
• pp.107-112
• /
• 2007

Laser wave length can have evaporation effect by absorption because outer skin or tissue of focus is consisted of water almost though absorption of water occurs more than 90% almost in formation thickness of very thin floor. Can operate outer skin, steam by floor and correct incision of formation is available. Suture surgical operation is available to vein or lymph system and surgical operation region can dry and see as eye and radish bleeding surgical operation is available. Specially, stability of tube both end output about pulse by weight very, this research can cause various curative effect because can reduce bulk and control easily current wave style of medical laser using electric power conversion device of high frequency way. If introduce ZVS (Zero Voltage Switching) or ZVZCS (Zero Voltage and Zero Current Switching), is more profitable because can reduce switching damage. Because electric power department of proposed medical laser can do stable soft-switching in wide subordinate extent introducing ZVZCS technique by the first help and control department composes microcontroller, output current waveform user have free form make Result that experiment because design and manufacture, brought result that improve of 20% than existing equipment, and will be bought to get into superior result if supplement as systematic late.

• The Journal of Engineering Geology
• /
• v.23 no.3
• /
• pp.247-256
• /
• 2013

The carbonate sands of the Sabkha layer in the Middle East have very low shear strength. Therefore, instant settlement and time-dependent secondary settlement occur when inner voids are exposed, as in the case of particle crushing. We analyzed settlement of the Sabkha layer under a large-scale foundation by hydrotesting, and compared the field test results with the results of laboratory tests. With ongoing particle crushing, we observed the following stress-strain behaviors: strain-hardening (Sabkha GL-1.5 m), strain-perfect (Sabkha GL-7.0 m), and strain-softening (Sabkha GL-7.5 m). General shear failure occurred most frequently in dense sand and firm ground. Although the stress-strain behavior of Sabkha layer carbonate sand that of strain-softening, the particle crushing strength was low compared with the strain-hardening and strain-perfect behaviors. The stress-strain behaviors differ between carbonate sand and quartz sand. If the relative density of quartz sand is increased, the shear strength is also increased. Continuous secondary compression settlement occurred during the hydrotests, after the dissipation of porewater pressure. Particle crushing strength is relatively low in the Sabkha layer and its stress-strain behavior is strain-softening or strain-perfect. The particle crushing effect is dominant factor affecting foundation settlement in the Sabkha layer.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.51 no.7
• /
• pp.593-598
• /
• 2006

This study was conducted to investigate the effect of tillage methods such as plowing and rotary tillage (PRT), rotary tillage (RTG), no-tillage after barley straw application (NTB), and barley straw mulching after plowing and rotary tillage (BPR) on the growth and the yield of soybean when cultivated after the cultivation of barley. The methods were compared with the control method in which plowing and rotary tillage after barley straw incineration was applied. Barley straw application resulted in increase in organic matter, total nitrogen, phosphate, and exchangeable cation regardless of tillage methods. Porosity and moisture level in paddy soil was ranked as follows : PRT > RTG > BPR > control > NTB. Decomposition rate of barley straw dramatically increased to 41.7% toward 30 days after soybean sowing, higher in NTB, DRB, and RTG than in BPR. Weed occurrence was decreased 36% in NTB and 40% in BPR. Root activity, nodulation and the dry weight per plant of soybean at flowering stage were highest in NTB and lowest in PRT. Soybean yield in NTB was 3,070 kg/ha increasing 19%, whereas that in PRT was not increased. Therefore in case of a frequent rain during the cultivation of soybean in paddy field PRT could result in excess moisture level in soil, the cultivation without tillage is desirable.

• International Journal of Highway Engineering
• /
• v.7 no.3 s.25
• /
• pp.31-42
• /
• 2005

This study evaluates the physical mechanical properties, durability and sound absorbtion of porous concrete for pavement according to content of silica fume and steel fiber to elicit the presentation of data and the way to enhance its function for the practical field application of porous concrete as a material of pavement. The results of the test indicate that in every condition, the void ratio and the coefficient of water permeability of porous concrete for pavement satisfy both the domestic standards and proposition values. Among the properties of strength, the compressive strength satisfies the standards in the specification of Korea National Housing Corporation as for every factor of mixture but in the case of the flexural strength, more than 0.6vol.% of steel fiber satisfied the Japan Concrete Institute proposition values. The mixture of silica fume and steel fiber presents the excellent intensity, though. The case when silica fume and steel fiber are used simultaneously presents the strongest durability because the durability shows the similar tendency to the dynamic characteristics. The case when 10wt.% of silica fume and 0.6vol.% of steel fiber are used at the same time shows that the loss rate of mass by Cantabro test became 27% better and freeze-thaw resistance became 60% better. As for the characteristics of sound absorption of porous concrete for pavement, Noise Reduction Coefficient is 0.48 to prove that it possesses almost 50% sound absorption.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.2
• /
• pp.98-102
• /
• 2009

Various physical properties of soils were investigated in the areas where organic farming had been practiced widely, for upland fields. The investigations were also conducted in the nearby fields under conventional to find out the influence of organic farming on the physical properties of soils. The investigated properties involved bulk density, hardness, shearing resistance, friction resistance, sinking depth of small rectangular board, water stable aggregates and the depth of soil available to plants. By and large, the practice of organic farming tended to improve all of the physical properties soils, investigated in upland soils. However, in case of water stable soil aggregates in upland soils, the reverse was previous data; in those soils water stable soil aggregates were less under organic farming. It was suspected that this might be due to intensive application of the organic materials with high C/N ratio like wood chips and wood bark. The contents of OM, Av. P2O5, and Ex. cations were higher in organic farming than those of nearby fields under conventional, due to heavy organic matter application. From the results, It could be concluded that soils under organic farming were looser and softer than those under conventional as shown by lower bulk density and hardness, but that the effect of organic farming on water stable aggregates were low.

• Korean Journal of Environmental Agriculture
• /
• v.26 no.4
• /
• pp.300-305
• /
• 2007

Soil erosion is one of the most serious problems in alpine upland in Korea. Soil fertility has continuously decreased due to serious soil erosion. To increase soil fertility, new sources of organic matter should be inputted. Therefore, the objectives of this research were to select winter cover crop as new sources of organic matter and to investigate the effect of winter cover crop on soil property changes, major crop productivity (Chinese cabbage, potato) production in highland, and disease occurrence with different cropping systems. Among 17 candidates for winter coverage crop, rye was most suitable due to it's soil covering rate, and over-wintering rate. The optimum sowing period for rye ranged from late August to late September. Soil porosity and organic matter content increased with rye cultivation. Rye cultivation during winter increased amounts of crop (both Chinese cabbage and potato) productivity up to 8%. There was little difference on amount of crop productivity depending on cropping systems such as monoculture (Chinese cabbage or potato) and Chinese cabbage-potato rotation.

• Economic and Environmental Geology
• /
• v.23 no.4
• /
• pp.425-452
• /
• 1990

A tentative hydrogeologic and hydrodispersive study was carried out to evaluate the groundwater pollution potential at a selected site by utilizing empirical assessment methodologies in an advanced stage of quantitative computer aided assessment. The upper most aquifer is defind as saturated overburden and weathered zone including the upper part of highly fractured rock. Representative hydraulic conductivity and storativity of the uppermost aquifer are estimated at 2.88 E-6 m/s and 0.09, respectively. Also calculated Darcian and average linear velocity of groundwater along the major pathway are 0.011 m/d and 0.12 m/d with average hydraulic gradient of 4.6% in the site. The results of empirical assessment methodologies indicate that 1) DRASTIC depicts that the site is situated on non-sensitive and non-vulnerable area. 2) Legrand numerical rating system shows that the probability of contamination and degree of acceptability are classed to "Maybe-Improbable, and Probable Acceptable and Marginally Unacceptable" with situation grade of "B". 3)Waste soil-site interaction matrix assessment categorizes that the study site is located on "Class-8 Site".

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.9 no.4
• /
• pp.247-259
• /
• 2007

In this study, we examined the flux of carbon and water using an eco-hydrological model, Regional Hydro-Ecologic Simulation System (RHESSys). Our purposes were to develop a set of parameters optimized for a well-designed experimental watershed (Gwangneung Research Watershed, GN) and then, to test suitability of the parameters for predicting carbon and water fluxes of other watershed with different regimes of climate, topography, and vegetation structure (i.e Gangseonry Watershed in Mt. Jumbong, GS). Field datasets of stream flow, soil water content (SWC), and wood biomass product (WBP) were utilized for model parameterization and validation. After laborious parameterization processes, RHESSys was validated with the field observations from the GN watershed. The parameter set identified at the GN watershed was then applied to the GS watershed in Mt. Jumbong, which resulted in good agreement for SWC but poor predictability for WBP. Our study showed that RHESSys simulated reliable SWC at the GS by adjusting site-specific porosity only. In contrast, vegetation productivity would require more rigorous site-specific parameterization and hence, further study is necessary to identify primary field ecophysiological variables for enhancing model parameterization and application to multiple watersheds.

• The Journal of Engineering Geology
• /
• v.30 no.2
• /
• pp.161-173
• /
• 2020

This study is to examine the engineering characteristics of colunmar joints in Mudeugsan National Park, a global geopark. For these purposes, physical and mechanical properties of Mudeungsan Tuff, evaluation for the weathering degree of columnar joints, and crack behavior monitoring in columnar joints were conducted. The physical properties of Mudeungsan tuff were 1.02% for the average porosity, 0.38% for the average absorption, 2.69 g/㎤ for the average specific gravity, and 4,948 m/s for the average elastic wave velocity. Its mechanical properties were 337 MPa for the average uniaxial compressive strength, 68 GPa for the average elastic modulus, 0.29 for the average Poisson's ratio, 41.3 MPa for the average cohesion strength, and 62.8° for the average friction angle. the average rebound Q-value of the silver Schmidt hammer for the three columnar joint blocks at the Ipseok-dae was shown as 49.3. when this value is converted into uniaxial compressive strength, it becomes 70.5 MPa, which is about 21% of the uniaxial compression strength of Mudeungsan tuff. In addition, according to the results of crack monitoring measurements for the three columnar joint blocks at the Ipseok-dae, the crack behavior is less than 1 mm, so it is believed that its behavior in Ipseak-dae columnar joints has hardly occured to date.

• Journal of the Korea Institute of Building Construction
• /
• v.11 no.6
• /
• pp.587-596
• /
• 2011

Ultra rapid-hardening cement is widely used for latex-modified mortar and concrete as repair and finishing material during urgent work. The purpose of this study is to evaluate the improvements in strength made to SBR cement mortars by the adding of various admixtures and by the use of different curing methods. SBR cement mortar was prepared with various polymer-cement ratios, curing conditions and admixture contents, and tested for flow, flexural and compressive strengths. From the test results, it was determined that the flow of SBR cement mortar increased with an increase in the polymer-cement ratio, and the water reducing ratio also increased. The strength of cement mortar is improved by using SBR emulsion, and is strengthened by adding metakaoline. The strength of SBR cement mortar cured in standard conditions was increased with an increase in the polymer-cement ratio, and attained the maximum strengths at polymer-cement ratios of 15 % and 10 %, respectively. The maximum strengths of SBR cement mortar are about 1.8 and 1.3 times the strengths of plain mortar, respectively. In this study, it is confirmed that the polymer-cement ratio and curing method are important factors for improving the strengths of rapid-hardening SBR cement mortar.