• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.421-428
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• 1988

The purpose of this study was to analyze the working time and the efficiency according to plot shape and plot size under the same conditions. We chose two stands which were relatively gently sloped end evenly distributed in number of trees and surveyed 198 plots, and 306 plots in each stand. 1. As to the time advantage of plot establishment method, the direct-four line establishment method was more favorable than the diagonal-line establishment method in a rectangular plot. 2. The method by Blumeleiss-$Me{\beta}$ trommel was more favorable than the method using a tape in a circular plot. 3. As to the time advantage, the circular plot was more favorable than the rectangular plot. Especially, the circular plot was twice more available than rectangular plot in small plot size, but enlargement of plot size gradually decreased time advantage of circular plot.

• Journal of Korean Society of Forest Science
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• v.4 no.1
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• pp.26-29
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• 1965

1. The purpose of this study was to find out the best sampling form and sampling unit in forest survey. 2. The value of small sampling unit was over estimated in comparison with that of large sampling unit. 3. The value of circular form was over estimated in comparison with that of the others. 4. The smallest unit for estimation in area sampling were as follows. a) 0.06 ha. in the rectangular plot. b) 0.08 ha. in the square plot. c) 0.10 ha. in the circular plot. 5. Conclusion was as follows. The best sampling unit was 0.06 hectoare in the rectangular plot, which was most economic above all and gave preferable result for in the forest survey.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.4
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• pp.13-21
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• 2004

The purpose of this study was to investigate tile effects of pending depth treatment on water balance in paddy fields. Field experiment was performed in an experimental farm in Taegu, southern part of Korea during the rice growing season In 2001, 2002 and 2003. Experimental plots were three 8m ${\times}$ 80m rectangular plots. Three pending depth treatments, very shallow, shallow, and deep were used. Daily values of water balance components were measured in the field. The irrigation amounts measured at the experimental plots showed that the very shallow and the shallow ponded plots required smaller amount than the deep ponded plot. The shallow ponded plot saved irrigation water about 17.7% compared with the traditional deep ponded plot in 2001 The very shallow ponded plot saved irrigation water about 25.7% compared with the traditional deep ponded Plot in 2002, The shallow ponded plot saved irrigation water about 18% compared with the deep ponded plot in 2003.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.6
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• pp.83-95
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• 2003

In this study, a new concept in a paddy consolidation project is introduced in that curved parallel terracing with contour-lined layout is adopted in sloping areas instead of conventional rectangular terracing. The contoured layout reduces earth-moving considerably compared to rectangular methods in consolidation projects. The objective of the paper is to develop a combinatorial optimization model using the network theory for the design of contour-lined plots which minimizes the volume of earth moving. The results showed that as the length of short side of plot is longer or the land slope is steeper, the volume of earth moving for land leveling increases. The developed optimization model is applied for three consolidated districts and the resulting optimal earth moving is compared with the volume of earth from the conventional method. The shorter is the minimum length of short side of a polt with increases the number of plots, the less is the volume of earth. As the minimum length of short side is 20 m for efficient field works by farm machinery, the volume of earth moving of optimal plot is less by 21.0∼27.1 % than that of the conventional consolidated plots.

• Magazine of the Korean Society of Agricultural Engineers
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• v.14 no.2
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• pp.2603-2609
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• 1972

A study on how the condition of farmland influences operating efficiency of a tractor came up with the following results in the primary experiment. (1) $10m{\times}30m$ plot of which length is shortest in this experiment, took a maximum of required time per onea plow, whereas $20m{\times}120m$ plot, whose length is longest in the same experiment, took a minimum of required time per one a to plow. It reveals, accordingly, that the proportion between width and length should be 1:6; the most desirable proportion that proves to most profitable in terms of time. (2) All the available efforts were made to diminish some unplowed parts of plot to a minimum. It was revealed, however, in the experiment that the ratio of unplowed plot leads to 7.52% in the plot 6; the highest ratio, and 3.44% in the plot 1; the lowe ratio. That shows us that the ratio of availability of land be higher in a more rectangular plot. (3) But even a rectangular plot allows lower ratio of availability in case that the width is narrow. It is showed that a higher ratio of availability can be obtained in when the width of plot is more than 20 meters at minimum. (4) In the operation of plowing by using a tracter, It was also revealed that we could not but have a quite a considerable loss in terms of both the ratio of availability and the required tine for plowing unless we maks a plan to with the unplowed part of plot.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.1
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• pp.49-58
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• 1992

The purpose of the experiment was to determine the effect of plant density and pattern on growth characteristics, total dry matter yield. protein yield and palatability of sorghum-sudangrass hybrid (Sordan 79). The main treatment was three levels of plant density (Skg, 15kg. 30kg/ha) and the sub treatment was two plant patterns of square and rectangular planting.The experiment was arranged as a split plot design and conducted on the Experimental Livestock Farm of Kon-Kuk Univ. in Chungju, 1989. The results obtained are summarized as follows :1. As the plant density was increased, plant length, leaf length, leaf width(P<0.05) and leaf number were gradually decreased, but in the same plant density, plant length, leaf length, leaf width and leaf number were generally increased in the rectangular plot. 2. In the first cutting time, the ratio of leaf was the highest at the rectangular plot of high density (30kg/ha, 25cm$\times$4cm), but in the second cutting time, the ratio of leaf was the highest at the square plot of medium density (15kg/ha, 14cm$\times$ 14cm). 3. The ratio of dead stubble after cutting was generally increased by increasing the plant density. Also, in the same planting density, the ratio of dead stubble was generally increased in the square plot. 4. The tiller number per plant tended to decreased by increasing thc plant density, and the tiller number was increased in the rectangular plot. In the same plant density. 5. Total fresh and dry matter yield were the highest at the rectangular plot of medium density (IS kg/ha, 33cm$\times$6cm) wholly, but the low density was shown the lowest.6. The crude protein content was increased by increasing the plant density per unit area(P<0.05) and the protein yield was also increased by increasing the planting density. 7. According to the increase of plant density, the stem was thinned, but NDF, ADF did not show different. The palatability was in the order of high (30kg/ha))medium (15kg/ha))low density(5kgiha) at the first cutting time, but it was in the order of high)low)medium density at the second cutting time.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.1
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• pp.19.2-19.2
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• 1992

The purpose of the experiment was to determine the effect of plant density and pattern on growthcharacteristics, total dry matter yield. protein yield and palatability of sorghum-sudangrass hybrid(Sordan 79). The main treatment was three levels of plant density (Skg, 15kg. 30kg/ha) and the subtreatment was two plant patterns of square and rectangular planting.The experiment was arranged as a split plot design and conducted on the Experimental Livestock Farm of Kon-Kuk Univ. in Chungju, 1989.The results obtained are summarized as follows :1. As the plant density was increased, plant length, leaf length, leaf width(P<0.05) and leaf number were gradually decreased, but in the same plant density, plant length, leaf length, leaf width and leaf number were generally increased in the rectangular plot.2. In the first cutting time, the ratio of leaf was the highest at the rectangular plot of high density(30kg/ha, 25cm$\times$4cm), but in the second cutting time, the ratio of leaf was the highest at the square plot of medium density (15kg/ha, 14cm$\times$ 14cm). 3. The ratio of dead stubble after cutting was generally increased by increasing the plant density. Also, in the same planting density, the ratio of dead stubble was generally increased in the square plot. 4. The tiller number per plant tended to decreased by increasing thc plant density, and the tiller number was increased in the rectangular plot. In the same plant density. 5. Total fresh and dry matter yield were the highest at the rectangular plot of medium density (ISkg/ha, 33cm$\times$6cm) wholly, but the low density was shown the lowest.6. The crude protein content was increased by increasing the plant density per unit area(P<0.05) and the protein yield was also increased by increasing the planting density. 7. According to the increase of plant density, the stem was thinned, but NDF, ADF did not show different. The palatability was in the order of high (30kg/ha))medium (15kg/ha))low density(5kgiha)at the first cutting time, but it was in the order of high)low)medium density at the second cutting time.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.1
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• pp.17-25
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• 1977

The purpose of this paper is to clarify the effect of wall proximity on the terminal velocity of single air bubbles in vertical tubes. As an initial step, experiments were conducted to determine the terminal velocity, shape, and path of single air bubbles rising freely in water. The terminal velocity of air bubbles rising through water was measured in cylindrical tubes, rectangular tubes, and parallel plates respectively. The results of effect wall of cylindrical tubes were shown as a dimensionless plot, and may also be used to arrive at a decision regarding the minimum size of tube.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.270-275
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• 2000

In this study, heat transfer and Pressure drop characteristics for R-718 in the plate and shell heat exchanger (P&SHE) investigated experimentally. The plates are circular and welded into a stack which fits into a cylindrical shell in P&SHE. Although apparently very different from rectangular the compact brazed plate heat exchanger (CBE), the underlying flow passage structure through the P&SHE is the same as in the CBE. The R-718 between plate side and shell side was performed a counterflow heat exchange. Heat transfer characteristic of R-718 were measured for turbulent flow in P&SHE by using wilson plot technique. Heat transfer experiment Ivas performed in the $200{\leq}Re{\leq}500$ regime and Pressure drop experiment was performed in the $150{\leq}Re{\leq}1600$ regime. The purpose of this study is to investigate heat transfer and friction factor correlations for R-718 in P&SHE and to offer fundamental data for experiment

• Structural Engineering and Mechanics
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• v.37 no.3
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• pp.331-349
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• 2011

This study investigates the use of a vibration correlation technique (VCT) to identify the buckling load of a rectangular thin plate. It is proposed that the buckling load can be determined experimentally using the natural frequencies of plates under tensile loading. A set of rectangular plates was tested for natural frequencies using an impact test method. Aluminum and stainless steel specimens with CCCC, CCCF and CFCF boundary conditions were included in the experiment. The measured buckling load was determined from the plot of the square of a measured natural frequency versus an in-plane load. The buckling loads from the measured vibration data match the numerical solutions very well. For specimens with well-defined boundary conditions, the average percentage difference between buckling loads from VCT and numerical solutions is -0.18% with a standard deviation of 5.05%. The proposed technique using vibration data in the tensile loading region has proven to be an accurate and reliable method which might be used to identify the buckling load of plates. Unlike other static methods, this correlation approach does not require drawing lines in the pre-buckling and post-buckling regions; thus, bias in data interpretation is avoided.