• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.929-934
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• 2000

Optimum stand density of alfalfa (Medicago sativa L.) varies with locations and climates. Stand density is one of the factors that determines herbage yield, forage quality and persistence of alfalfa. As establishment costs increase, the question arises whether present population densities are optimum for obtaining maximum herbage yield and forage quality. The objectives of this study were: 1) to determine the optimum plant density for highest herbage yield and forage quality for the dehydrated alfalfa industry under Edmontons climatic conditions in Alberta, Canada; 2) to compare herbage yield and forage quality of the cultivars 'Algonquin' and 'Vernal' grown at a range of stand densities. Alfalfa seedlings of both cultivars were either transplanted at spacings of 6, 10, 15 and 25 cm or direct seeded at the 4.5 cm plant spacings, providing population densities of 494, 278, 100, 45 and $16plants/m^2$. The experimental design was a randomized complete block with a split-plot arrangement having three replicates; the main plots consisted of two alfalfa cultivars Algonquin and Vernal, and the sub-plots were the five population densities. The cultivar Vernal had significantly higher annual yield than did the cultivar Algonquin. There was no significant effect of plant density on herbage yield. There was no difference in crude protein (CP) between the two cultivars. At the first cut, there was a significant quadratic effect of plant density on CP content and the greatest CP occurred at the 100 plants/m2 density. Crude protein was not affected by plant density at the second cut. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) were not affected by plant density. The cultivar Algonquin usually had a lower ADF and NDF than cultivar Vernal. In conclusion, high population densities ($278plants/m^2$ or more) of alfalfa did not improve herbage yield and forage quality compared with low plant population densities ($100plants/m^2$ or less) of alfalfa.

• Korean Journal of Exercise Nutrition
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• v.25 no.3
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• pp.36-43
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• 2021

[Purpose] Exercise is a key factor in preventing obesity and metabolic syndrome. Sumo wrestlers increase their body size from childhood for athletic advantage; however, the risk of metabolic syndrome in junior sumo wrestlers is undetermined. Preventive measures against pediatric obesity should be initiated during childhood to prevent obesity in adulthood, considering its high global incidence. We comparatively evaluated the risk factors for metabolic syndrome in junior sumo wrestlers and children with obesity. [Methods] We enrolled 70 male children (age 9-17 years [sumo group, n = 14] and 9-14 years [other sports and non-exercise groups, n = 28 each]) and evaluated their anthropometric parameters (height, weight, body mass index z-score, obesity rate, waist circumference, waist to height ratio) and hematological parameters (total, low-density, high-density, and non-high-density lipoprotein-cholesterol; triglycerides; plasma glucose, and glycated hemoglobin levels). [Results] The BMI z-score, obesity rate, waist circumference (p < 0.05, along with the non-exercise group), and systolic blood pressure were significantly higher and the high-density cholesterol level was lower in the sumo group than in the other sports group (p < 0.05). The waist to height ratio was significantly higher in the non-exercise group than in the other sports group (p < 0.05). No significant difference was found in other blood lipid, plasma glucose (significantly lower level than the reference range in the sumo group, p < 0.05), and glycated hemoglobin (within the reference range in all groups) levels among the three groups. [Conclusion] Junior sumo wrestlers had a larger body size and higher blood pressure than children with obesity who exercised regularly. This provides direction for future research into targeted preventive interventions against metabolic syndrome for junior sumo wrestlers with large body size.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.916-926
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• 1994

A high frequency and soft-switched AC-to-DC rectifier employing a series-type resonant circuit is proposed to overcome the disadvantages of the conventional peak-rectifying circuit. Using the proposed rectifier, the high power factor and low harmonic currents are obtained in the AC line. Furthermore, several advantages such as the high power density and wide output voltage range can be available. Through the simulation and experimental results, the usefulness of the proposed rectifier is verified.

• Journal of Environmental Science International
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• v.12 no.4
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• pp.461-467
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• 2003

This study was conducted to provide the basic information to know reasonable method f3r the removal and treatment of municipal solid wastes(MSWs). MSWs four different sources(apartment residence, commerce, office/industry) in Daegu city were collected, and bulk density, physical composition, moisture, combustible, ash, elements and heating values were investigated. The values of bulk density were at range of 0.30∼0.41ton/m$^3$. The percentages of foods, papers, vinyls/plastics, textiles, rubbers/leathers, metals and glasses/ceramics of wet muncipal solid wastes from three sources except office/industry were at range of 27.3∼46.4%, 21.2∼38.4%, 10.3∼11.9%, 3.8∼5.2%, 0.5∼1.7%, 6.9∼8.7% and 1.9∼2.6% respectively. The percentages of papers, foods, vinyls/plastics, textiles, rubbers/leathers, metals and glasses/ceramics of dry muncipal solid wastes from three sources except office/industry were at range of 21.1∼40.4%, 14.2∼30.1%, 15.2∼17.8%, 4.0∼6.0%, 0.9∼2.8%, 12.2∼14.1% and 3.1∼3.7％ respectively. The moisture contents of foods, woods, textiles and papers in wastes were at range of 65.7∼76.2%, 34.6∼50.0%, 22.2∼44.8 and 30.6∼44.4% respectively. The carbon contents of vinyls/plastics, rubbers/leathers, textiles, woods, papers and foods in wastes were at range of 75.88∼79.87%, 58.24∼70.74%, 45.23∼51.63%, 42.29∼45.58%, 40.19∼48.4% and 25.86∼36.25% respectively. The low heating values of foods, papers, woods, textiles, rubbers/leathers and vinyls/plastics by Dulong's law were at range of 178∼1,353kcal/kg, 770∼1,660kcal/kg, 995∼1,629kcal/kg, 2,133∼2,432kca1/kg, 4,200∼7,275 kcal/kg and 6,384∼8,722kcal/kg respectively, and the high heating values of them were at range of 782∼2,056 kcal/kg, 2,459∼3,314kca1/kg, 3,056∼3,592kcal/kg, 4,381∼5,087kca1/kg, 5,005∼8,066kca1/kg and 10,032∼10,739 kcal/kg respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.1
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• pp.22-29
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• 1991

This study was experimented to obtain the basic information on the changeable aspect and improvement of soil fertility in newly-reclaimed sloped land. Silage corn was cultivated under the six different treatments for 4 years. The relation between the amount or ratio of annual changes of soil physico-chemical properties and yield of silage corn were analyzed. Soil bulk density was decreased in 3rd year at topsoil, but that decreased in 4th year at subsoil. Soil organic matter also decreased in 2nd year at topsoil, and decreased continuously at subsoil. Bulk density and hardness of soil depths showed significant negative simple correlation with dry matter yield and cation exchange capacity showed positive. Correlation coefficient of chemical properties with dry matter yield were low. The range of annual changes of moisture percent, hardness and organic matter were wider than the other properties. The significantly different of physical properties were higher than the chemical properties, and those of topsoil were higher than subsoil. According to multiple regression between yield and physico-chemical properties of subsoil, bulk density and cation exchange capacity were in the greatest contribution at the variations, but bulk density was greatest at the ratios.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.299-303
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• 2002

The relationship of crystallinity between defects distribution with (100) ZnTe/GaAs using HWE growth was investigated by four crystal rocking curve (FCRC) and transmission electron microscopy (TEM). The thickness dependence of crystal quality in ZnTe epilayer was evaluated. The FWHM value shows a strong dependence on ZnTe epilayer thickness. For the films thinner than 6 ${\mu}{\textrm}{m}$, the FWHM value decreases very steeply as the thickness increases. For the films thicker than 6 ${\mu}{\textrm}{m}$, it becomes an almost constant value. At the thickness of 12 $\mu\textrm{m}$ with the smallest value of 66 arcsec. which is the best value so far reported on ZnTe epilayers was obtained. Investigation into the nature and behavior of dislocations with film thickness in (100) ZnTe/(100)GaAs heterostructures grown by Hot Wall Epitaxy (HWE). This film defects range from interface to 0.7 ${\mu}{\textrm}{m}$ thickness was high density, due to the large lattice mismatch and thermal expansion coefficients. The thickness of 0.7~1.8 ${\mu}{\textrm}{m}$ was exists low defect density. In the thicker range than 1.8 ${\mu}{\textrm}{m}$ thickness was measured hardly defects.

• Journal of Magnetics
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• v.20 no.4
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• pp.371-376
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• 2015

Magnetite nanoparticles were synthesized by adding excess ammonium hydroxide to a solution of iron (II) and (III) chlorides. The surfactants of oleic acid and Span 80 were applied in sequence to the magnetic particles as a combined stabilizer, and poly-${\alpha}$-olefin (PAO) 30 or 60 was used as the liquid base with a low or high viscosity, respectively. The ferrofluids were prepared with the concentrations of 200, 300, 400, and 500 mg/mL, and characterized by density, dispersion, magnetization, and viscosity. The density of the fluids increased proportionally to the concentration from 0.98 to 1.27 g/mL and 1.01 to 1.30 g/mL with PAO 30 base and PAO 60 base, and the dispersion stability was 77-95 and 81-74% for the PAO-30 and PAO-60-based fluids, respectively. The observed saturation magnetization values of the PAO-30 and PAO-60-based ferrofluids were 16 to 42 mT and 17 to 41 mT with the concentration increase in the range 200-500 mg/mL, respectively, depending upon the content of magnetic particles in the fluid. The viscosity variation of the PAO-30 and PAO-60-based ferrofluids in the temperature range $20-80^{\circ}C$ was the least with the concentrations of 400 and 300 mg/mL, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.837-843
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• 2009

$TiO_2$(2 wt.%)-doped ZnO(TZO) films with thickness from 100 nm to 500 nm were prepared on polyethylene naphthalate(PEN) substrate under various rf-power range from 40 W to 80 W. Their electrical and optical properties were investigated as a function of rf-power. We think that these properties were closely related with the crystallization and the film density of TZO films. It was also presumed that the vaporization of the water vapor and other adsorbed particles such as an organic solvents can affect the electrical properties of the conventional transparent conductive oxide(TCO) films. On the other hand, since the TZO film deposited on glass substrate at room temperature with rf-power of 80 W shows a very low resistivity of $7.5\times10^{-4}\;\Omega{\cdot}cm$ and a very excellent transmittance over an average 85% in the visible range, that is comparable to that of ITO films. Therefore, we expect that the TZO films can be used as transparent electrode for optoelectronic devices such as touch-panels, flat-panel displays, and thin-film solar cells.

• Journal of the Korean Vacuum Society
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• v.9 no.1
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• pp.7-15
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• 2000

An ECR-PECVD system with the characteristics of high ionization rat다 ability of plasma processing in a wide pressure range and deposition at low temperature was manufactured and characterized for the deposition of thin films. The system consists of a vacuum chamber, sample stage, vacuum gauge, vacuum pump, gas injection part, vacuum sealing valve, ECR source and a control part. The control of system is carried out by the microprocessor and the ROM program. We have investigated the vacuum characteristics of ECR-PECVD system, and also have diagnosed the characteristics of ECR microwave plasma by using the Langmuir probe. From the data of system and plasma characterization, we could confirmed the stability of pressure in the vacuum chamber according to the variation of gas flow rate and the effect of ion bombardment by the negative DC self bias voltage. The plasma density was increased with the increase of gas flow rate and ECR power. On the other hand, it was decreased with the increase of horizontal radius and distance between ECR source and probe. The calculated plasma densities were in the range of 49.7\times10^{11}\sim3.7\times10^{12}\textrm{cm}^{-3}$. It is also expected that we can estimate the thickness uniformity of film fabricated by the ECR-PECVD system from the distribution of the plasma density.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.364-368
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• 2021

We developed a highly efficient organic photovoltaic (OPV) cell with a poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)]:[6,6]-phenyl-C71-butyric acid methyl ester active layer for harvesting lower-intensity indoor light energy to power various self-powered sensor systems that require power in the microwatt range. In order to achieve higher power conversion efficiency (PCE), we first optimized the thickness of the active layer of the OPV cell through optical simulations. Next, we fabricated an OPV cell with optimized active layer thickness. The device exhibited a PCE of 12.23%, open circuit voltage of 0.66 V, short-circuit current density of 97.7 ㎂/cm², and fill factor of 60.53%. Furthermore, the device showed a maximum power density of 45 ㎼/cm², which is suitable for powering a low-power (microwatt range) sensor system.