• Korean Journal of Plant Resources
• /
• v.32 no.6
• /
• pp.735-742
• /
• 2019

This study investigated a suitable method that could be applied for Asian chain fern [Woodwardia japonica (L. f.) Sm.] to propagate gametophytes and promote sporophyte formation. The gametophytes used in all experiments were obtained from germinated spores in vitro and were subcultured at 8-week intervals. The most appropriate media for gametophyte propagation was identified by culturing 300 mg of gametophyte in Murashige and Skoog (MS) basal medium (1/8, 1/4, 1/2, 1, 2), and Knop medium for 8 weeks. As a result, fresh weight of the gametophyte was increased by 56.7-fold on MS medium. Moreover, antheridium formation as well as gametophyte growth was improved on MS medium, especially. To improve the sporophyte formation ex vitro, 1.0 g of gametophyte was ground with distilled water and spread on eight combinations onto four different culture mediums, such as bed soil, peat moss, perlite and decomposed granite. Then generation and growth of sporophytes were investigated after cultivation for 10 weeks. As a result of this experiment, peat moss had a promotive effect of sporophyte formation at single-use and mixed culture soils. In particular, a mixture of bed soil, peat moss and perlite in a 1:1:1 ratio (v/v/v) led to the accelerated formation (782.5 ea/pot) and the frond growth of sporophytes. This included increases in length and width of fronds. However, promotive effect of gametophyte growth and sporophyte formation was not found at single-use and treatment with high ratio of bed soil.

• The Journal of Engineering Geology
• /
• v.16 no.1 s.47
• /
• pp.1-14
• /
• 2006

Various measurements were carried out to estimate the modulus of deformation in two dominant rock types in Korea: granite and gneiss. Four most commonly used methods were utilized: Goodman jack tests, PS well logging, laboratory ultrasonic tests and laboratory uniaxial loading tests. Laboratory static and dynamic Young's moduli depend on the magnitude of the applied axial stress, range of Sequency used for measurement and the loading/unloading condition. As the laboratory measurement condition approaches to that in situ, the resultant moduli also appear to be comparable to that in situ. This suggests that the simulation of in situ stress condition is important when the modulus of rock is determined in the laboratory Dynamic Young's modulus is generally higher than static Young's modulus because of (micro)crack behavior in response to the stress, different range of frequency used for measurements, and the effect of the amplitude of deformation. Understanding of the relations in moduli from different measurement methods will help estimate appropriate in situ values.

• The Journal of Engineering Geology
• /
• v.5 no.3
• /
• pp.237-274
• /
• 1995

This study was focused on the improvement of the measurement technique of P-wave velocity for the assesment of the anisotropy of the engineering property of rock. Samples used were collected from a working quarry within the Carnmenellis granite area on which series of engineering geological data have been accumulated. This study mainly concerned the development of measurement technique at the curved surface of rock, the use of natural honey-based coupling agent and the drying method for rock specimen over $P_2O_5$. According to the results, the range of the P-wave velocity anisotropy in two dimensional plane, fell between 0 and 4.68 (%). The direction where maximum velocity occurred was parallel to the orientation of the maximum in-situ stress. The result showed that P - wave velocity is a useful measure to asses the anisotropy of the engineering property of rock and it is suggested that the improvements adopted here can be applied to the experimental work on the rocks in Korea.

• The Journal of Engineering Geology
• /
• v.13 no.2
• /
• pp.171-191
• /
• 2003

The objective of this present study is to understand long term(500 years) thermohydromechanical interaction behavior on joints adjacent to a repository cavern, when high level radioactive wastes are disposed of within discontinuous granitic rock masses, and then, to contribute this understanding to the development of a disposal concept. The model includes a saturated discontinuous granitic rock mass, PWR spent nuclear fuels in a disposal canister surrounded with compacted bentonite inside a deposition hole, and mixed bentonite backfilled in the rest of the space within a repository cavern. It is assumed that two joint sets exist within a model. Joint set 1 includes joints of $56^{\circ}$ dip angle, spaced 20m apart, and joint set 2 is in the perpendicular direction to joint set 1 and includes joints of $34^{\circ}$ dip angle, spaced 20m apart. The two dimensional distinct element code, UDEC is used for the analysis. To understand the joint behavior adjacent to the repository cavern, Barton-Bandis joint model is used. Effect of the decay heat from PWR spent fuels on the repository model has been analyzed, and a steady state flow algorithm is used for the hydraulic analysis.

• The Journal of Engineering Geology
• /
• v.2 no.2
• /
• pp.113-130
• /
• 1992

Groundwater in crystalline basement is controlled primarily by tectonic fractures. It is evident that the delineation of the heavily faulted area and/or fractures deeply developped should be considerable value in deep-seated low enthalphy geothermal water. Electrical and electromagnetic methods have effectively been employed to map hydraulic faults and shear zones for groundwater exploration. In this study VLi; dipoledipole resistivity, controlled source audio~frequency magneto-telluric(CSAMT) and magnetic methods were applied in the Bomun resort area, adjacent to Kyongju city, southeastern part of Korea. The integrated geophysical tools employed in this experiment can be manifested themselves as: 1. Magnetic high for granite intrusions which is more favorable for geothermal gradient increase in depth. 2. VLF cross-over trends for mapping linear shallow conductive fractures and shear zones. 3. Dipole-dipole resistivity distributions for the deep-seated(less than 500m in depth) fractures and shear zones. The dipole-dipole resistivity field data were inverted to the true resistivity distribution with two-dimensional automatic inversion program based on the finite-difference method. 4. CSAMT provides an efficient way of delineating fractures and fault zones if the depth is greater than about 500m.

• The Journal of Engineering Geology
• /
• v.14 no.2
• /
• pp.211-222
• /
• 2004

In this study, a probabilistic prediction model for debris flow occurrence was developed using a logistic regression analysis. The model can be applicable to metamorphic rocks and granite area. order to develop the prediction model, detailed field survey and laboratory soil tests were conducted both in the northern and the southern Gyeonggi province and in Sangju, Gyeongbuk province, Korea. The seven landslide triggering factors were selected by a logistic regression analysis as well as several basic statistical analyses. The seven factors consist of two topographic factors and five geological and geotechnical factors. The model assigns a weight value to each selected factor. The verification results reveal that the model has 90.74% of prediction accuracy. Therefore, it is possible to predict landslide occurrence in a probabilistic and quantitative manner.

• The Journal of Engineering Geology
• /
• v.29 no.4
• /
• pp.405-415
• /
• 2019

The cracks induced by hydraulic rock splitting technique are formed in the direction parallel to the free plane, which is perpendicular to the minimum principal stress of the ground, or is affected by the pre-existing microcracks. In this study, the hydraulic rock splitting experiments were conducted in which the guide slot was engraved in the direction parallel to the borehole axis on the biotite granite slope, and the hydraulic pressure was injected through the double packer pressure and interval section. The test results show that the cracks along with the guide slots were induced either by the double packer pressurization or the injection of hydraulic pressure into interval section, some cracks extended across the boreholes. Therefore, the hydraulic rock splitting test is expected to control efficiently the induced cracks if the guide slots are engraved in the direction of splitting and a big flow rate is applied.

• The Journal of Engineering Geology
• /
• v.27 no.1
• /
• pp.41-49
• /
• 2017

In this study, we tried to confirm the influence range in the ground due to Bulbed, Reinforcement change and ground conditions change through numerical analysis. By checking the increase width of the reinforcement effect accompanying the increase of Bulbed, grasping the trend accompanying the change of the ground conditions and deciding soil nail Reinforcement and Bulbed, so that economical construction will be carried out It can be judged that it can be utilized as basic material. In this paper, we analyzed the Displacement due to positional load of reinforcement by utilizing MIDAS GTS NX which is a universal numerical analysis program. In addition, it is necessary to ensure the diameter star economy of Bulbed size and Reinforcement by comparing / analyzing whether the Bulbed relaxation region of Reinforcement represents arbitrary characteristics in the ground in Sandy soil, Weathered granite soil ground due to soil nail pullout load Numerical analysis was conducted to select criteria that can be done.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.6 no.6
• /
• pp.49-55
• /
• 2003

Total phosphorous removal rate was examined of a subsurface-flow treatment wetland system which was constructed on floodplain in the down reach of the Kwangju Stream in Korea from May to June 2001. Its dimensions were 29 meter in length, 9 meter in width and 0.65 meter in depth. A bottom layer of 45 cm in depth was filled with crushed granite with about 15~30 mm in diameter and a middle layer of 10 cm in depth had pea pebbles with about 10 mm in diameter. An upper layer of 5 cm in depth contained course sand. Reeds(Phragmites australis) were transplanted on the surface of the system. They were dug out of natural wetlands and stems were cut at about 40 cm height from their bottom ends. Water of the Kwangju Stream flowed from a submerged dam into it via a pipe by gravity flow and treated effluent was funneled back into the Stream. The number of reed stems increased from 80 stems/$m^2$ in July 2001 to 136 stems/$m^2$ in September 2001. The hight of stems was 44.2 cm in July 2001 and 75.3 cm in September 2001. The establishment of reeds at early operating stage of the system was good. Volume and water quality of inflow and outflow were investigated from July 2001 through December 2001. The average inflow was 40 $m^3$/day and hydraulic detention time was about 1.5 days. The concentration of total phosphorous n influent and effluent was 0.83 and 0.33 mg/L, respectively. The removal rate of total phosphorous averaged about 60%. The removal efficiency was slightly higher, compared with that of subsurface-flow wetlands operating in North America, whose retention rate of total phosphorous was reported to be about 56%. The good abatement rate could be attributed to sedimentation of particle phosphorous in pores of the media and adsorption of phosphorous to the biofilm developed on the surface of them. Increase of standing density of reeds within a few years will develop root zones which may lead to increment in the phosphorous retention rate.

• Economic and Environmental Geology
• /
• v.33 no.6
• /
• pp.491-504
• /
• 2000

Environmental isotope $^{18}O$, $^{2}H$, $^{3}H$,$^{13}C$, $^{34}S$and $^{87}Sr/^{86}Sr$) studies on ${CO_2}$-rich waters in the Kangwon Province were carried out to elucidate the origin, residence time, water-rock interaction and mixing process of their. ${\delta}^{18}O$ and ${\delta}D$ data indicate that ${CO_2}$-rich waters were derived from the local meteoric water. It also shows that each type of ${CO_2}$-rich water has distinct isotopic composition and Na-${HCO_3}$ type water (-10.8 to -12.1${\textperthousand}$, ${\delta}^{18}O$ ) is lighter than other type waters. These depleted isotopic values supposedly indicate that, considering the altitude effect of isotope in Korea, the recharge area of Na-${HCO_3}$ type water can be estimated to be relatively higher in elevation than those of Ca-${HCO_3}$ and Ca-Na-${HCO_3}$ type waters. Tritium contents close to zero are observed in the Na-${HCO_3}$ type water, confirming a long residence time and the possibility of a ${CO_2}$ inflow into the aquifer at great depth. These isotope data also show that the Ca-${HCO_3}$ type water has undergone mixing process with surface water during ascending at depth, whereas Na-${HCO_3}$ type water was less mixed with surface waters. The carbon isotope data (-8.8 to ＋0.8 ${\textperthousand}$ ${\delta}^{13}C$) indicate that dissolved carbon in the ${CO_2}$-rich waters was possibly derived from deep seated ${CO_2}$ gas. The high ${\delta}^{34}S$ values (up to 38.1${\textperthousand}$) of dissolved sulfates suggest that sulfate reduction by microbial activity had occurred at depth. Strontium isotopic data ($^{87}Sr/^{86}Sr$) of ${CO_2}$-rich waters indicate that the chemistry of the ${CO_2}$-rich waters is determined by water-rock (granite) interaction.