• Steel and Composite Structures
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• v.19 no.5
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• pp.1299-1319
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• 2015

This paper presents a detailed parametric study, conducted using finite element tools to cover a range of several geometric and material parameters, on the behaviour of thin-walled partially encased composite (PEC) columns. The PEC columns studied herein are composed of thin-walled built-up H-shaped steel sections with concrete infill cast between the flanges. Transverse links are provided between the opposing flanges to improve resistance to local buckling. The parametric study is confined to eccentrically-loaded columns subjected to major axis bending only. The parameters that were varied include the overall column slenderness ratio (L/d), load eccentricity ratio (e/d), link spacing-to-depth ratio (s/d), flange plate slenderness ratio (b/t) and concrete compressive strength ($f_{cu}$). The overall column slenderness ratio was chosen to be the primary variable with values of 5, 10 and 15. Other parameters were varied within each case of L/d ratio. The effects of the selected parameters on the behaviour of PEC columns were studied with respect to the failure mode, peak axial load, axial load versus average axial strain response, axial load versus lateral displacement response, moment versus lateral displacement behaviour and the axial load-moment interaction diagram. The results of the parametric study are presented in the paper and the influences of each of the parameters investigated are discussed.

• Korean Journal of Plant Resources
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• v.33 no.6
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• pp.586-596
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• 2020

Chionanthus retusus has been used for landscaping and gardening trees, foods and medicines. This study was carried out to analyze the effect of fertilization on the growth performance of container seedlings (1-year-old) in C. retusus. We used multifeed 19 (MF) as a fertilizer, and measured the height, root collar diameter (RCD), biomass, seedling quality index (SQI) chlorophyll contents and chlorophyll fluorescence of the seedlings. The findings of this paper showed that the height, RCD, H/D ratio, T/R ratio and the fresh and dry weight of seedlings increased after fertilization. The moisture content of the stem and root did not show any significant difference among fertilizations, except in the case of the leaf. Production distribution such as the dry weight ratio of leaves and the stem dry weight ratio of fertilized seedlings had a higher value than that of non-treatment. SQI was the highest in MF 1,000 mg/L and 2,000 mg/L treatment. Chlorophyll contents (SPAD value) also increased with the increase in fertilization concentrations. Chlorophyll fluorescence (F_v/F_m) showed the highest value of 0.8 in MF 2,000 mg/L treatment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.373-379
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• 2016

Hydraulic forces on a vessel are changed according to the depth/draft ratio (h/d) during berthing or towing in a lateral direction. It is well known that lateral current force coefficient is dependent on the kinds of vessel in question. However, not much research exists about the characteristics of general ships, except for oil tankers, as suggested by the Oil Companies International Marine Forum (OCIMF). In this paper, lateral current coefficient related to h/d is analyzed in comparison with theoretical values and experiments with a 93m passenger ship. The estimated total resistance on the ship was 14.0 tons under an h/d of 1.6 with a lateral current force coefficient of 1.9. This was found to be similar to the measured value of 13.8 tons on the towing line in actual experiments. Resistances on the ship under an h/d of 3.0 was calculated to be 19.9 tons with a lateral current force coefficient of 1.3. Therefore, the lateral current force coefficient was expected to be 1.3 under an h/d of 3.0, in experiments measured value 20.0 tons. And the discharging currents did not affect the towing force if the towing line was over 30 m, since the towing resistance showed a similar tendency for changes in line length from 30 m to 60 m.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.152-157
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• 2005

This experimental study was devoted to investigate skin friction of H group piles with uplift loading conditions in granite soil under laboratory test. Model piles made of steel embedded in weathered granite soil were used in this study. Pile arrangements($2{\times}2,\;3{\times}3$), pile space(2D, 4D, 6D), and soil density($D_r=40%,\;80%$) were tested. The main results obtained from the model tests can be summarized as follows. The series of tests found that ultimate uplift load and displacement for group piles were increased as piles space ratio increases to $D_r=40%$ of soil density. In the relative density of $D_r=80%$, bearing capacity for group piles was greater than for single pile. In the relative density of $D_r=40%$, the theoretical value of skin friction for group piles was greater than practical value. In the relative density of $D_r=80%$, both theoretical and practical value of skin friction for group piles were increased as piles space ratio increases.

• Journal of Microbiology and Biotechnology
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• v.11 no.2
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• pp.329-332
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• 2001

It has been known that, in enzymatic synthesis of cephalexin, the conversion yield was reduced by high loading of ampicillin acylase. In order to elucidate this phenomena, pH-controlled synthesis of cephalexin was examined using a purified Acetobacter turbidans acylase. When the pH of the reaction mixture was maintained at $6.20{\pm}0.04$, the reduction of the maximal conversion rate was not observed even with high enzyme loading. The kinetic parameters also suggest that pH drop during the enzymatic synthesis of cephalexin was mainly attributed to the rapid hydrolysis of D-${\alpha}$-phenylglycine methyl ester to D-${\alpha}$-phenylglycine, rather than the disappearance of 7-amino-3-deacetoxycephalosporanic acid for cephalexin synthesis. At higher molar ratio of two substrates, [D-${\alpha}$-phenylglycine methyl ester]/[7-amino-3-deacetoxycephalosporanic acid], the conversion rate was also elevated under pH-controlled enzymatic synthesis, which implies that the main reason for the pH drop is due to the production of D-${\alpha}$-phenylglycine methyl easter, the effect of a water-methanol cosolvent system on the ester, the effect of a water-methanol cosolvent system on the conversion profile was also examined. Even the though the conversion rate was increased in 10% methanol solution, a higher than 16% methanol in the reaction mixture caused an inactivation of enzyme.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.95-100
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• 2004

H-pile can be more easily driven than pipe pile by pile driver and shows high skin friction and plugging effect. And lately It is well grown that the high strength H-pile has been widely used f3r pile foundations. To compare the skin frictions of H piles under different density soil conditions, this paper presents results of a series of model tests on vertically loaded group piles. Model piles made of steel embedded in weathered granite soil were used in this study. Pile arrangements $(2\times2,\;3\tunes3)$, pile space(2D, 4D, 6D), and soil density$(D_r=40\%,\;80\%)$ were tested. The main results obtained from the model tests can be summarized as follows. The series of tests found that compression load for group piles increases as number of piles increase and piles space ratic decrease to $D_r=40\%$ of soil density. The analysis also found that the theoretical value of skin friction for group piles is greater than practical value as piles space ratio increases to $D_r=40\%$ of soil density. Piles showed the greatest difference of the skin friction in case that the pile space ratio(S/D) is 6. The theoretical value by Meyerhof and DM-7 showed 1.83 times and 1.32 times respectively as great as practical value in case of S/D=6 and $2\times2$.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.361-364
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• 2002

This paper discusses the influencing factors such as coring position, height to diameter ratio of core specimen(h/d) and coring torque on the strength estimation of concrete by small site coring method in order to verify the validities of small size core method. According to results, as for the influence of drilling position, when core specimens are obtained from the place parallel to placing direction, compressive strength of core specimens are higher than those perpendicular to placing direction. This is due to the loss of the area of core specimen perpendicular to plating direction by bleeding. And in case of $\phi$ 24mm core specimen, when vertical drilling against placing direction is taken. compressive strength of core specimen obtained at the bottom of the structure is higher than that at the top of the structure. As for the influence of height to depth ratio, as h/d ratio increases compressive strength shows to be decreased. As for the influences of rotation speed of drilling machine, as its speed goes up, compressive strength decreases, regardless of core diameter.

• Journal of Korean Society of Forest Science
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• v.106 no.4
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• pp.480-486
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• 2017

This study was conducted to develop the merchantable stem volume models to predict the volume up to upper diameter or upper height out of the total stem volume, targeting on Pinus densiflora, Pinus koraiensis, and Larix kaempferi in South Korea. The 131 stemmed sample trees for stem analysis were used as the data for developing the models. The six kinds of merchantable volume equations including merchantable volume ratio form, ratio form, and exponential ratio form were examined to develop the best models. The two models were finally selected as the best models to predict the merchantable volume: $V_d=V_t\{{\exp}[{\alpha}_1(d^{{\alpha}_2}/D^{{\alpha}_3})]\}$ for upper diameter and $V_h=V_t\{1+{\beta}_1(P^{{\beta}_2}/H^{{\beta}_3})\}$ for upper height. By rearranging the best model equations, implicit taper functions were derived, and the estimation was performed for the upper height by upper diameter and upper diameter by upper height. Because of not only the high accuracy but also the convenience, the models developed in this study were considered to be easily applicable in the field of forestry.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1291-1302
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• 2020

To verify the field-effectiveness of Terrestrial Laser Scanner (TLS), a terrestrial LiDAR was deployed to examine the damage properties of woods in forest fire area, then the data was compared with the results surveyed by a forestry expert. Four sample plots (30 m × 50 m, 0.15 ha) were set from the foot to the top of the mountain, and DBH, height, clear length, burned height, and crown length were investigated. Next, TLS collected information on damage characteristics found in the sample plots. This information was then compared with that amassed by the expert. The expert and the TLS survey results showed 30.8 cm and 29.9 cm for DBH, 15.8 m and 17.5 m for tree height, 8.4 m and 8.4 m for clear length, 4.0 m, 3.5 m for burned height, and 7.4 cm and 9.1 cm for crown length. With the exceptions of height and clear length, no notable discrepancy was observed between two methods. H/D ratio, CL/H ratio, and BH/CL ratio, all of which contribute to stability and decay rate of the stand, from the two methods were also compared. The human survey rated each ratio (H/D, CL/H, BH/CL in order) 51.3%, 47.1%, and 53.6%, while the TLS presented the results of 58.8%, 52.0%, and 38.7%.

• Transactions on Electrical and Electronic Materials
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• v.14 no.5
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• pp.246-249
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• 2013

Graphene was obtained on Cu foil by thermal decomposition method. A gas mixture of $H_2$ and $CH_4$ and an ambient annealing temperature of $1,000^{\circ}C$ were used during the deposition for 30 Min., and for the transfer onto $SiO_2/Si$ and Si substrates. The physical properties of graphene were investigated with regard to the effect ofnitrogen atom doping and the various substrates used. The G/2D ratio decreased when the graphene became monolayer graphene. The graphene grown on $SiO_2/Si$ substrate showed a low intensity of the G/2D ratio, because the polarity of the $SiO_2$ layer improved the quality of graphene. The intensity of the G/2D ratio of graphene doped with nitrogen atoms increased with the doping time. The quality of graphene depended on the concentration of the nitrogen doping and chemical properties of substrates. High-quality monolayer graphene was obtained with a low G/2D ratio. The increase in the intensity of the G/2D ratios corresponded to a blue shift in the 2D peaks.