• Water Engineering Research
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• 제3권1호
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• pp.9-22
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• 2002

In general, two dimensionless numbers are used in predicting the front propagation rate of density currents: the densimetric Froude number and the dimensionless front velocity. The former expresses the front speed in terms of the characteristic length and reduced gravitational acceleration. Previous papers report that the range of this dimensionless number is wide. The other is the dimensionless front velocity, which is a function of the buoyancy flux per unit width. This paper presents the state of the art review of the dimensionless numbers for the front propagation rate of density currents. Values of the densimetric Froude number are found to be consistent when the proper characteristic length is used for normalization. Then, the densimetric Froude number and the dimensionless front velocity are compared by using the experimental data of density currents over a horizontal surface.

• 한국응용곤충학회지
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• 제12권4호
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• pp.143-146
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• 1973

벼 이삭선충(심고선충), Aphelenchoides besseyi Christie의 접종밀도가 벼의 생육 및 본선충의 자성충의 체장에 미치는 영향을 알기 위하여 온실내에서 포트시험을 수행하였다. 선충을 접종하였을 경우에 벼의 초장, 분벽수 및 지상부의 건물중의 감소를 초래했으며 접종밀도가 높아짐에 따라 자성충의 체장도 감소하였다.

• 소성∙가공
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• 제18권6호
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• pp.482-487
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• 2009

A finite element based microstructural modeling for the size dependent strengthening of particle reinforced aluminum composites is presented. The model accounts explicitly for the enhanced strength in a discretely defined "punched zone" around the particle in an aluminum matrix composite as a result of geometrically necessary dislocations developed through a CTE mismatch. The density of geometrically necessary dislocations is calculated considering volume fraction of the particle. Results show that predicted flow stresses with different particle size are in good agreement with experiments. It is also shown that 0.2% offset yield stresses increases with smaller particles and larger volume fractions and this length-scale effect on the enhanced strength can be observed by explicitly including GND region around the particle. The strengths predicted with the inclusion of volume fraction in the density equation are slightly lower than those without.

• Membrane and Water Treatment
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• 제15권1호
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• pp.11-19
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• 2024

This study presents the characteristics of growth and morphology of Anabaena sp., a representative filamentous cyanobacterium, depending on temperature variation from 10 to 30 ℃. Both the filament density (or number) and its length of Anabaena were highly affected by temperature, as well as growth stage. Rapid growth at a higher temperature led to an increase in Anabaena filament density, as well as optical density at 680 nm (OD₆₈₀). However, the number of vegetative cells within a single filament of Anabaena grown at 30 ℃ was smaller than those grown at lower temperatures, due to the intercalary division of the filament. Of the three different cells comprising a single Anabaena filament, the vegetative cell marginally affects the growth of Anabaena. The main dimensions of the vegetative cell, i.e., length and width, depend on the temperature and growth stage. The length-to-width (L/W) ratios of vegetative cells and akinetes were relatively consistent regardless of the temperature. However, in vegetative cells with dichotomous growth, the L/W ratio shows clear differences depending on their growth stage. It has been demonstrated that the L/W ratio could be used as an indicator to indirectly predict the growth stage of on-sit Anabaena samples.

• 한국표면공학회지
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• 제53권6호
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• pp.312-321
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• 2020

Morphology of porous cobalt electro-deposits was systematically investigated as functions of cobalt precursors in the plating bath and applied cathodic current density with a special focus on cobalt nano-rod formation. It was proved that the concentration of cobalt precursor plays little effect on the morphology of cobalt electro-deposits at relatively low plating current density while it significantly affects the morphology with increasing plating current density. Such a dependence was discussed in terms of the kinetics of two competitive reactions of cobalt reduction and hydrogen evolution. Cobalt nano-rod structure was created at specific ranges of cobalt precursor content and applied cathodic current density, and its diameter and length varied with plating time without notable formation of side branches which is usually found during dendrite formation. Specifically, the nano-rod length was preferentially increased in relative short plating time (<15 s), resulting in higher aspect ratio of nano-rod with plating time. Whereas, both the nano-rod length and diameter were increased nearly at the same level in a prolonged plating time, making the aspect ratio unchanged. From the analysis of crystal structure, it was confirmed that the cobalt nano-rod preferentially grew in the form of single crystal on a dense poly-crystalline cobalt thin film initially formed on the substrate.

• Plant Resources
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• 제8권3호
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• pp.258-262
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• 2005

In autumn, to determine the optimal planting date and plant density of rapeseed in southern areas of Korea, Yudal variety for autumn sowing, the highest yielding variety was grown under three different planting dates and five different plant densities. Yield components such as plant height, ear length, number of seedling stand per $m^2$, number of branches and pod length were highest at the plots with Sep. 30 of planting date and 30/20 cm drilling of plant density. Yield of seed, oil and 1,000 grains weight were highest at the Sep.30 of planting date and 30/20 cm drilling of plant density. Judging from the results reported above, at optimum planting date and plant density of rapeseed seemed to be Sep.30 of planting date and 30/20cm plant density in autumn sowing.

• 한국패류학회지
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• 제30권1호
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• pp.17-23
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• 2014

여수 횡간도 지역에서 밀도별 피조개 각장 과 전중량의 성장은 밀도와 역 상관관계를 보였다. 밀도별 각장 평균성장은 10마리구가 5.21 mm로 가장 양호하였으며 밀도가 높을수록 각장 성장은 낮아졌다. 밀도별 전중량의 증가도 같은 결과를 보여 전반적으로 10-20마리구의 평균각장 및 평균 전중량의 증가가 30-40마리구에 비하여 양호하게 나타났다. 남해해역에서 밀도별 피조개 각장과 전중량의 성장도 밀도와 역 상관관계를 보였으나 여수해역보다 약한 역 상관관계를 보였다. 밀도별 각장 평균성장은 10마리구가 4.55 mm로 가장 양호한 결과를 보였으나, 20-40마리구의 밀도별 평균각장의 성장은 3.11, 3.36, 3.27 mm로 비슷하게 나타났다. 반면에 밀도별 전중량의 증가는 10-20마리구가 30-40마리구보다 많았다. 결론적으로 피조개의 수하양성시 양성밀도는 20마리/$0.12m^2$ (166마리/$1m^2$) 가 적당하다고 사료되었다. 여수해역에서 피조개의 생존율은 밀도별로 각각 68%-87%, 로 밀도의존적 결과를 보였으나, 먹이생물인 식물플랑크톤이 풍부한 남해해역의 생존율은 91%-100%로 월등히 양호한 결과를 보였는데, 이는 여수해역의 식물플랑크톤의 양이 남해해역의 55.89%에 불과하였기 때문이라 사료된다. 수하 양성 해역별의 수온범위는 $16.22-25.66^{\circ}C$였고, 염분은 30.07-33.48였으며, pH는 8.10-8.45범위였다. 그리고 용존산소 (DO) 는 4.49-9.65 mg/L 였다.

• 한국산업융합학회 논문집
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• 제3권4호
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• pp.337-343
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• 2000

Physical properties of matt georgette knitted fabrics, which has been developed recently, were investigated to provide fundamental information for the textile industry. Dimensional characteristics were examined with three different loop lengths, where the plain knitted fabrics were knitted with cotton yam and polyester yarn. The matt georgette plain knitted stitch was fully relaxed after wet relaxation treatment at $130^{\circ}C$ for 30minutes and subsequent tumble dry treatment at $70^{\circ}C$ for 90minutes. As the treatment temperature of wet relaxation became higher and the loop length did shorter, all of stitch density, course density and wale density were increased with 31 of $K_1$ 8.3 of $K_2$ and 3.8 of $K_3$. Also, The higher value of $K_4$ could be obtain with shorter loop length. When the loop length became longer, the $K_4$ value was varied in a wide range with the treatment of wet relaxation and subsequent tumble dry.

• Journal of the Korean Wood Science and Technology
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• 제24권4호
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• pp.56-63
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• 1996

This study was to manufacture thinned wood of Larix leptolepis Gordon into Oriented Strand Board(OSB) with Urea-Formaldehyde Resin. The OSB was made of four kinds of strand in slenderness ratio 150 ; thickness $0.3{\pm}0.05mm$, $0.4{\pm}0.05mm$, $0.5{\pm}0.05mm$ and $0.6{\pm}0.05mm$, respectively length 45mm, 60mm, 75mm and 90mm. Target densities were 0.65gr/$cm^3$, 0.75gr/$cm^3$ and 0.85gr/$cm^3$. The stepwise 9 minutes-multi-pressing schedule in the maximum pressure 40kgf/$cm^2$, the minimum pressure 10kgf/$cm^2$ was applied for $400mm{\times}390mm{\times}12mm$ board at the temperature of $150^{\circ}C$ in a hot press. In MOR The OSB of thin strand thickness $0.3{\pm}0.05mm$(length 45mm) and density 0.85gr/$cm^3$ was the highest. The strand thickness had more effect on MOR than the strand length. In strand thickness $0.4{\pm}0.05mm$(length 60mm) and density 0.85gr/$cm^3$ was the highest MOE. The strand thickness and length had adverse effects on MOE each other. At internal bonding. The OSB of strand thickness $0.3{\pm}0.05mm$(length 45mm) and board density 0.75gr/$cm^3$ showed the highest value. OSB had higher IB value with thinner strand thickness. The thinner strand thickness showed the lower thickness swelling in turn $0.3{\pm}0.05mm$(length 45mm), $0.4{\pm}0.05mm$(length 60mm), $0.5{\pm}0.05mm$(length 75mm). $0.6{\pm}0.05mm$(length 90mm). Target densities 0.75gr/$cm^3$ 0.65gr/$cm^3$, 0.85gr/$cm^3$ showed in turn lower value. Finally, The OSB made of thinned wood of Larix leptolepis Gordon showed good results in laboratory experiment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.488-491
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• 2000

Bi-2223/Ag superconducting wires have been mainly prepared by a powder-in-tube method. The drawing and the rolling are main processes to increase the core density and wire length. In the fabrication of long wire, especially, the drawing should be precisely controlled to assure the filament homogeneity. In this paper, the influences of drawing die angle, bearing length and reduction ratio on the sausaging and the critical current density of the wire are investigated. Single cored and multi-filamentary wires are fabricated by PIT method with different conditions. The core densities and sausaging in the wires are investigated and are discussed regarding their relationship to the I$_{c}$. It was made clear that the geometry of drawing die is sensitively dependent on the sausaging. The improvement of I$_{c}$ was achieved by reducing the die angle and high core density.ity.