• Korean Journal of Weed Science
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• v.11 no.3
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• pp.205-210
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• 1991

The freezing resistance of Eleocharis kuroguqai was evaluated in artifical and natural freezing conditions in relation to tuber size, depth of tuber burial and soil moisture conditions. Osmotic potential of immature and mature tuber of E. kuroguqai before hardening was -12.1 and -23.5 bar, respectively, but decreased to -61. 0 and -67.1 bar after 120-day hardening period. Percent survival of E. kuroguqai tubers during the winter period was 13% and 67% in dry and moist moisture conditions at burial of 5cm depth, but all tubers were survived in the three moisture conditions employed when buried at 25cm depth. Greater decrease of osmotic potential was observed in tubers buried at 5cm depth than tubers buried at 25cm depth, resulting in greater freezing resistance in the former. Large tuber was more susceptable to freezing temperatures than small tuber.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.433-444
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• 1975

This study was conducted to investigate the strength of lime soil mixtures for varied' curing temperatures(20, 30, 40, 50, $60^{\circ}C$) and lime content (3, 6, 9, 12%) in four lime-stabilized soils(KY : Sand, MH : Sand, SS: Sandy loam. JJ : Loam). The experimental results obtained from unconfined compressive strength tests are as follows; 1. The optimum moisture content increased and maximum dry density decreased with the increase of the lime content. 2. The lime content for the maximum strength of SS and JJ soils showed at the 9 percent lime content, but KY and MH soils didn't show the tendency of increase and decrease by the lime content and curing period. The rate of decrease of the soaked unconfined compressive strength showed the lower value in accordance with lime content. 3. According to increase in curing temperatures in curing temperatures at 30, 40, 50, $60^{\circ}C$, the unconfined compressive strength of lime soil mixtures increased, the rate of increase initially increased at a rapid rate, and showed that around 120 hours were sufficient curing time to complete hardening. 4. The average maximum temperature of Korea being around $30^{\circ}C$ from July to August, thus these months are ideal construction periods to increase the strehgth of lime soil mixtures. 5. Accelerated curing times equivalent to 28-day normal curing decreased in accordance with the increase of curing temperature, and showed shorter in lime soil mixtures than soil cement. 6. Accelerated curing times versus normal curing times are formed as a linear, its slope decreased in accordance with the increase of curing temperature, it may be expressed as follows: (1). $30^{\circ}C$ : t=2.63d-1.4(r=0.99) (2). $40^{\circ}C$ : t= 1.76d-0.8(r=0.97) (3). $50^{\circ}C$ : t=1.35d-3.2(r=0.94) (4). $60^{\circ}C$ : t=0.49d+1.8(r=0.91) in which t ; Accelerated curing time d ; Normal curing time.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.96-104
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• 2008

In this study, the observation of test pieces with an optical microscope was carried out after fabricating 4 groups of standard lacquer, in order to inquire into the ancient lacquering techniques. Group I had transparent reddish brown color, and the part of layer was indefinite, and the layer polished was easily distinguished. Group II had mostly transparent yellowish brown color, and it was possibility distinguished the layers when they were varnished with mixed lacquer after prime coating, and when they were varnished with lacquer as the prime coating. Group III set up membrane in the hardening process of the lacquer, and the lacquer and the unsaturated fatty acid of internal part was dried, so the top layer and the lacquer layer were separated and observed. Group IV: When the lacquer coat film of Group IV test pieces were observed in polarized light, the ferrous components were seen as the black and red color were mixed, and the silica crystals of silty soil were distinguished by reflection of lights. And the colors were distinguished as the lacquer layer of ruddle had red color, and the mixed lacquer of reddish lacquer and ruddle had the deep red color at the top and the bottom, but the middle part had the bright red color.

• Journal of the Korean GEO-environmental Society
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• v.3 no.4
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• pp.67-79
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• 2002

The purpose of this study is to present criteria of selection of optimum grout materials through analyzing the limitation of permeability of each materials(MSG-N, OPC), in various ground conditions by comparing presentation of strength and permeability of MSG method and LW method(or SGR method). To do that, physical and chemical characteristics of grout materials were analyzed and compressive tests of homogel, mixed coagulation materials and hardening materials in certain mixing ratio, and of milk paste. In addition, permeability tests for each ground soil, each injection pressure, and each materials in combined stratum were performed with massive chamber. The results of tests showed that ultra fine grout materials like grout of MSG is necessary to construct effective grouting in sand and silty sand ground. Also, it is expected to become chemical grouting guide data to layout construction engineers because presented proper injection pressure by kind of object ground in case using ultra-fine grout material.

• Journal of the Korean Applied Science and Technology
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• v.13 no.2
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• pp.85-92
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• 1996

Chitosan itself has been prepared using chitin, one of the most abundant compounds in nature, as a starting material. We have synthesized the water-soluble chitosan derivative, N-dithiocarboxy chitosan sodium salt, through the reaction of water-soluble chitosan with carbon disulfide in the presence of alkali metal hydroxide. To elucidate this natural polymer capacity of adsorbing heavy metal ions, we have performed adsorption experiments using the water-soluble chitosan derivative various average molecular weight and of different percent contents of sulfur. The effect of pH, adsorption time and temperature on adsorption efficiency was also studied. The adsorbent derived from water-soluble chitosan of average molecular weight ranging $9,000{\sim}120,000$ was shown to have the highest capacity of adsorbing heavy metal ions. On the whole, adsorbing efficiency was increased as the reaction time goes longer and also increased as the reaction temperture goes higer in temperture range of $15^{\circ}C{\sim}45^{\circ}C$. The adsorption capacity at various pH, however, was appeared to vary depending on the heavy metal ions studied Judging from these finding, water-soluble N-dithiocarboxy chitosan sodium salt, a derivative of a biodegradable nature polymer, is believed to be a potential adsorbent for heavy metal ions since it not only is shown to lower the concentration of heavy metal ions to below the drainage quality standard, but also it would not cause acidification and hardening of soil which is one of the detrimental effects of synthetic macromolecular adsorbents present.

• Journal of Ginseng Research
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• v.28 no.4
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• pp.211-214
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• 2004

This study was carried out to find out the optimum hardening condition for ginseng plantlets redifferentiated by tissue culture method. While a lot of root hair were observed on the root of seedling grown on the soil, few root hair were observed on the root of plantlet redifferentiated in vitro. On the medium solidified with $0.1{\%}$ phytagel, root hair was not observed and root weight, root width and laternal root development were also very poor. While raising the phytagel concentration on the media, root hair began to increase and root weight, root width and latemal root development were improved. Vascular tissue of plantlet grown on the medium with $0.1{\%}$ phytagel was very poor, but that of plantlet grown on the medium with $0.8{\%}$ phytagel was very good.

• Plant Biotechnology Reports
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• v.4 no.4
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• pp.321-328
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• 2010

An efficient protocol for in vitro organogenesis was achieved from callus-derived immature and mature leaf explants of Momordica charantia, a very important vegetable and medicinal plant. Calluses were induced from immature leaf explants excised from in vitro (15-day-old seedlings) mature leaf explants of vivo plants (45 days old). The explants were grown on Murashige and Skoog (MS) medium with Gamborg (B5) vitamins containing 30 g $1^{-1}$ sucrose, 2.2 g $1^{-1}$ Gelrite, and 7.7 lM naphthalene acetic acid (NAA) with 2.2 ${\mu}M$ thidiazuron (TDZ). Regeneration of adventitious shoots from callus (30-40 shoots per explant) was achieved on MS medium containing 5.5 ${\mu}M$ TDZ, 2.2 ${\mu}M$ NAA, and 3.3 ${\mu}M$ silver nitrate ($AgNO_3$). The shoots (1.0 cm length) were excised from callus and elongated in MS medium fortified with 3.5 ${\mu}M$ gibberellic acid ($GA_3$). The elongated shoots were rooted in MS medium supplemented with 4.0 ${\mu}M$ indole 3-butyric acid (IBA). Rooted plants were acclimatized in the greenhouse and subsequently established in soil with a survival rate of 90%. This protocol yielded an average of 40 plants per leaf explant with a culture period of 98 days.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.5
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• pp.23-29
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• 2008

This study investigates the dynamic instability of strength-limited bilinear single degree of freedom (SDF) systems under seismic excitation. The strength-limited bilinear hysteretic model best replicates the hysteretic behavior of the steel moment resisting frames. To estimate the dynamic instability of SDF systems, the collapse strength ratio is used, which is the yield-strength reduction factor when collapse occurs. Statistical studies are carried out to estimate median collapse strength ratios and those dispersions of strength-limited bilinear SDF systems with given natural periods, hardening stiffness ratios, post-capping stiffness ratios, ductility and damping ratios ranging from 2 to 20% subjected to 240 earthquake ground motions recorded on stiff soil sites. Equations to calculate median and standard deviation of collapse strength ratios in strength-limited bilinear SDF systems are obtained through nonlinear regression analysis. By using the proposed equations, this study estimated the probabilistic distribution of collapse strength ratios, and compared this with the exact values from which the accuracy of the proposed equations was verified.

• Journal of agriculture & life science
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• v.44 no.6
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• pp.39-44
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• 2010

An efficient method for the rapid propagation of Smilax china from axillary buds was established. Plants with thick leafage were selected from Korea native S. china population. Axillary buds of S. china collected from selected plant and were cultured in various culture media (2MS, MS, 1/2MS, WPM, B5 and SH medium). Shoot was induced from axillary bud on MS basal medium after 4 weeks of culture. 1/2MS medium showed a higher growth rate than those of the others, while the lowest shoot growth was obtained in 2MS medium. Among the sucrose concentrations, 5% sucrose was the optimum level for shoots growth from axillay buds. Among cytokinins, $0.5mgL^{-1}$ 6-benzylaminopurine (BAP) treatment showed the best performance on shoot multiplication, yielding average shoot multiplication forming about 2.4. Rooting was induced directly near the base of the shoot on 1/2MS medium containing with three-auxins ${\alpha}-napthalene$ acetic acid (NAA), indole acetic acid (IAA) and ${\beta}-indolebutyric$ acid (IBA) (0.5 and $1.0mgL^{-1}$). The $1.0mgL^{-1}$ IBA treatments induced earliest rooting with maximum of root number and root growth. These rooted plantlets were successfully transferred to pots for 4 weeks hardening process, and were transferred to soil with above 90% survival rate.

• Geomechanics and Engineering
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• v.30 no.6
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• pp.565-577
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• 2022

In this study, a series of three-dimensional numerical parametric study was conducted to investigate deformation mechanisms of an existing box culvert due to an adjacent multi-propped basement excavation in clays. Field measurements from an excavation case history are first used to calibrate a baseline Hardening Soil Small Strain (HS-small) model, which is subsequently adopted for parametric study. Results indicate that the basement-box culvert interaction along the basement centerline can be considered as a plane strain condition when the length of excavation (L) reaches 14 H_e (i.e., final excavation depth). If a plane strain condition (i.e., L/H_e=12.0) is assumed for analyzing the basement-box culvert interaction of a short excavation (i.e., L/H_e=2.0), the maximum settlement and horizontal movement of the box culvert are overestimated significantly by up to 15.7 and 5.1 times, respectively. It is also found that the deformation of box culvert can be greatly affected by the basement excavation if the distance between the box culvert and retaining wall is less than 1.5 H_e. The induced deformation in the box culvert can be dramatically reduced by improving the ground inside the excavation or implementing other precautionary measures. For example, by adding jet grouting columns within the basement and installing an isolation wall behind the retaining structures, the maximum settlements of box culvert are shown to reduce by 37.2% and 13.4%, respectively.