• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.355-358
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• 2003

This paper presents characteristics of vacuum preloaded porous air bearing. Pressure distribution of a porous pad and vacuum pocket are calculated. And load capacity and stiffness of the bearing are analyzed with various vacuum parameters, that is. clearance height. tube diameter, tube length. pumping speed of vacuum pump, vacuum pocket to porous pad area ratio. From the simulation results, optimum clearance for best performance can be selected adjusting these parameters, especially tube diameter which is the most dominant source.

• Korean journal of applied entomology
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• v.44 no.4 s.141
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• pp.293-298
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• 2005

The embryonic and postembryonic developments of Pierodorus hybneri Linnaeus were observed in 5 different rearing cages such as A (Cylindrical, 10 cm in diameter, height of 4 cm), B (Cylindrical, 14.5 cm in diameter, height of 2.8 cm), C (Rectangle, 6.5 by 6.5 cm in $length{\times}breadth$, height of 10 cm), D (Cylindrical, 9 cm in bottom diameter, 11.5 cm in upper diameter, height of 10.8 cm) and E (Cylindrical, 15 cm in diameter, height of 7.5 cm) containing soybean and peanut seeds as feeding food, and sponge-water container under laboratory condition of $24^{\circ}C$ and 16L:8D. Egg duration was 6 days regardless of rearing cages. Hatchability ranged from 63 to 80% with the highest in B (14.5 cm in diameter, 2.8 cm in height) rearing cage. Instar duration was longer from 5 days in 1st instar to about 11 days in 5th instar. Nymphal duration showed 35 to 36 days with'3ut significant difference in rearing cages. Percent emergence was in range from 65 to 82% with the highest in B rearing cage. Adult longevity was 35 to 83 days for male, and 32 to 79 days for female, and was the longest in B rearing cage. Total number of eggs laid by female adult was in range from 38 to 86 with significant difference in rearing cages, and was the most in B rearing cage. Accordingly, the reproductive rate of P. hybneri for 1 generation was within 17 to 56 times, and was the highest in B rearing cage. Therefore, it could be concluded that B cage is most suitable for stable rearing of P. hybneri under laboratory condition.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.85-96
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• 2000

An Eggcrate assembly is an important part to hold and support 16,000 tubes containing hot and contaminated water in the steam generator of nuclear power plant. As a great number of tubes should be inserted into the eggcrate assembly, the dimensions of each eggcrate grid are one of the critical factors to determine the availability of tube insertion. in this paper. we propose a machine vision algorithm for measuring the inner-circle diameter of each eggcrate grid whose shape is not exact quadrangular. The overall procedure of the algorithm is composed of camera calibration, eggcrate image preprocessing, grid height adjustment, and inner-circle diameter estimation. The algorithm is tested on real specimens and the results show that the algorithm works fairly well.

• Solar Energy
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• v.11 no.2
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• pp.34-40
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• 1991

Thermal stratification enhancement for the higher extraction efficiency of hot water storage tank was experimentally studied with transparent fiber glass cylindical tank($350{\ell}$, D=516mm, H=1680mm). Height to diameter ratio (H/D =1,2,3), flow rate(Q= 8,10,12LPM), inlet-outlet temperature differences(${\Delta}T=20,25,30^{\circ}C$), and geometry of inlet-outlet port were the parameters. In particular, three kind of distributors were used for geometry of inlet-outlet port. As a result, it was possible to get extraction efficiency of 95% by using the distributor having variable diameter but keeping a constant diameter of perforation. So it is recommendable to design the distributor so that the main pipe decrease in diameter toward the dead end.

• Journal of Environmental Science International
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• v.27 no.7
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• pp.555-560
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• 2018

This study conducted to analyze the growth characteristics of old Prunus yedoensis on Jeju island. The diameter growth per year was measured using a DTRS-2000 instrument. The DBH, ground DBH and height of the investigated P. yedoensis were 137 cm, 143 cm, and 15.5 m, respectively. Our analysis showed that the age of the old P. yedoensis was 93 years. An annual diameter growth of $2.85mm{\pm}0.96$ was observed. The result of age estimation, about $265{\pm}64$ years in P. yedoensis on Jeju island. This information could be useful to understand the annual diameter growth characteristics the P. yedoensis distributed on Jeju island.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.737-742
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• 2006

This paper numerically investigates to evaluate the performance according to the number of passes and the inlet/outlet diameter in a multi-pass multi-branch heat exchanger. A JF factor is used as an evaluation characteristic value to consider the heat transfer rate and the pressure drop simultaneously. It estimates the performance according to the number of passes and the inlet diameter of the reference heat exchanger. When the ratio of the inlet diameter to the header height is about 0.5, the optimum number of passes is selected along with the inlet diameter.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.142-145
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• 2007

Growth characteristics according to mixture ratio of used-rockwool in pot nursery, in Pinus densiflora, Torreya nucifera, Quercus acutissina and Fraxinus mandshurica nursery, was investigated. The used-rockwool on mixture ratio between used-rockwool and control (peatmoss: pearlite=1:1, v/v) were 0%, 30%, 50% and 70%. Flesh weight, dry weight and height of tree, in Pinus densiflora nursery, increased much more in 50% and 70% media but trunk diameter of tree had no difference according to mixture ratio. In Torreya nucifera nursery, flesh weight and height of tree in 70% medium and trunk diameter and numbers of shoot of tree in 50% and 70% media increased. Flesh weight, height and trunk diameter of tree, and chlorophyll (SPAD) and photosynthesis rate, in Quercus acutissina nursery, increased much more in 50% and 70% media, but dry weight of tree had only difference between non-mixed and mixed with rockwool. In Fraxinus mandshurica nursery, flesh weight and photosynthesis rate of tree increased much more in 70% medium, height, trunk diameter and total chlorophyll of tree had difference according to non-mixed and mixed with rockwool or had no only difference according to mixture ratio, respectively.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.275-283
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• 2010

This study was conducted to examine the changes in growths of tomato and watermelon seedlings and the relationship among growth parameters which are used to evaluate healthy seedling as affected by shading. Plants were grown under 0%, 25%, 50%, and 75% shadings using polyethylene films. Leaf area index (LAI) of tomato and grafted watermelon seedlings increased under 50% and 75% shading. Total dry weight decreased with increase of shading level. The growth rates of stem diameter, LAI, total weight were faster under 50% and 75% shading with increase of integral radiation than under 0% and 25% shading. Stem diameters of tomato and grafted watermelon seedlings showed no significant differences among shading regimes. Stem diameters of tomato seedlings had upward tendency with increase of total dry weight and shoot height, but there were no significant differences among shading regimes. Stem diameters of grafted watermelon seedlings had no relationship with shoot height. These results indicate that stem diameter of tomato seedlings is not appropriate for assessing seedlings quality but stem diameter of grafted watermelon seedlings with shoot height is available.

• Journal of Korean Society of Forest Science
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• v.26 no.1
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• pp.13-18
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• 1975

This study was intended to clarify interrelations among seven characters of bamboo and their influences upon its culm-volume. The analysis of covariance was used to obtain phenotypic correlations, genotypic correlations and environmental correlations among some characters of Phyllostachys bambusoides Sieb. et Zucc., and thereby path-coefficients were calculated based on Dewey's method. The characters considered here included the breast height diameter, culm-height, clear-length, subterranean stem, number of bamboo joints, butt-end diameter and culm-volume of bamboo. Average values, standard errors, variances and standard deviations for the characters mentioned above are shown in Table 1, and phenotypic correlations, genotypic correlations and environmental correlations among seven characters are shown in Table 2, according to the results, there are highly significant relationships among lines but not among some replications. According to Table 4, heritability values in the breast height and butt-end diameters are higher than those in other characters mentioned above. On the other hand, environmental correlations among general characters appear to have lower values than phenotypic and genotypic correlations do. It also appears that the butt-end diameter and breast height diameter are highly correlated with the culm-volume of bamboo. The path-coefficients of individual characters to the culm-volume of bamboo are computed from the correlations (Table 4) and presented in Figure 1 and Table 5, where it could shown the direct and indirect effects on the bamboo culm-volume of each character.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.2
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• pp.97-102
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• 1999

This study was conducted to compare seasonal changes of height, diameter at root collar, biomass and chlorophyll contents of Abies holophylla seedlings grown in Sangju National University Nursery under different light intensities. Four light intensities were adopted using nylon net such as 100% sunlight(1800 $\mu$㏖ m$^{-2}$ s$^{-1}$ ), 75% of sunlight (1350 $\mu$㏖ m$^{-2}$ s$^{-1}$ ), 50% of sunlight (900 $\mu$㏖ m$^{-2}$ s$^{-1}$ ) and 25% of sunlight (450 $\mu$㏖ m$^{-2}$ s$^{-1}$ ). Planting density in four light intensities was 30 cm$\times$30 cm. In each treatment, 100 trees were planted and height, diameter at root collar, biomass and chlorophyll contents were measured. The highest height, diameter at root collar and biomass in Abies holophylla seedlings were observed at 100% full sunlight. Lowest chlorophyll contents (Chlorophyll a, b and total) were shown at 25% of sunlight, lowest light intensity treatment in this study. Growths and chlorophyll contents of Abies holophylla seedlings were strongly associated with light intensity. Photosynthesis has to be investigated in near future because photosynthesis and chlorophyll contents were strongly related to tree growth with long periods.