• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.994-1001
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• 2012

The Effects of operating variables on reactivity of two $CO_2$ absorbents (PKM1-SU and P4-600) for SEWGS process were investigated in a pressurized fluidized bed reactor. For both $CO_2$ absorbents, $CO_2$ sorption capacity decreased as the number of absorption-regeneration cycles increased. PKM1-SU absorbent represented higher $CO_2$ sorption capacity than that of P4-600 absorbent. However, P4-600 absorbent represented better performance than PKM1-SU absorbent from the view points of regeneration temperature and regeneration rate. For PKM1-SU absorbent, $CO_2$ sorption capacity increased as the steam concentration increased. However, $CO_2$ sorption capacity increased initially as the steam concentration increased from 5% to 10%, but maintained thereafter for P4-600 absorbent. For both $CO_2$ absorbents, $CO_2$ sorption capacity increased as the final regeneration temperature increased. For PKM1-SU absorbent, $CO_2$ sorption capacity increased as the pressure increased and the increment tendency was drastic at higher pressure than 15 bar.

• Korean Journal of Ichthyology
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• v.10 no.2
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• pp.207-215
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• 1998

Just after hatching the embryo has a yolk sac and straighted digestive tract. Just after parturition in 5.0mm TL the mouth and anus were opened. In the larval stage of 5.2mm TL, digestive tract could be divided into pharynx, esophagus, stomach, pyloric caeca and intestine of the early differentiated state. The esophagus of larvae in 5.3mm TL has a PAS positive mucous cell. From over 5.7mm TL, PAS positive goblet cell recognized in the intestine. PAS positive absorptive cell began to appear in the intestine from 5.9mm TL. Yolky materials were absorbed completely in 6.0mm TL. In the larvae of B.5mm TL, gastric glands were observed in the mucosa, but the surface epithelium did not have PAS positive granules. From over 9.0mm TL, the histological structure of esophagus showed similar to adult. In the juvenile stage from 13.0mm to 15.0mm TL, histological structure of the stomach, pyloric caeca and intestine showed similar to adult. From the ultrastructural and histochemical study, it is concluded that the functional digestive tract is present in the juvenile stage from 18.0mm to 20.0mm TL.

• Korean Journal of Ichthyology
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• v.11 no.1
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• pp.46-51
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• 1999

Age, hatching date and growth in length of juvenile Limanda yokohamae were determined by analysis of microstructure in otoliths. Monthly samples were collected by a beach seine in the shallow water off Gaduk-do from January to December, 1998. The juveniles were collected between February and April. Mean total length was $22.6{\pm}1.77\;mm$ ($\pm$SD) in February, $23.6{\pm}3.86\;mm$ in March, and $38.2{\pm}8.38\;mm$ in April. The core of otoliths ranged from 18 to $21\;{\mu}m$ in diameter and the growth increments were deposited concentrically from the hatching mark. The secondary growth layer began to appear at the 48 to 56-th increment. It indicates that L. yokohamae larvae may be completed the metamorphosis at this time of ca. 52 d after hatching, and moved into the shallow water for demersal stage. The hatching date calculated from the number of daily increments was between late November and early January, showing a peak in December. The total length (L, mm) was related to otolith radius (R, ${\mu}m$); L=0.055 R+5.81 ($r^2=0.88$). The growth in total length was represented by the Gompertz growth curve; $L_t=3.39e^{4.51(1-e^{-0.0067t})}$ ($r^2=0.81$). Daily growth rate was 0.35 mm/d at the age of 70 d and increased up to 0.55 mm/d at the age of 120 d.

• Membrane Journal
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• v.17 no.3
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• pp.269-275
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• 2007

Sodium type faujasite(FAU) zeolite membranes with a thickness of 5${\mu}m$ and a Si/Al molar ratio of 1.5 were prepared by the secondary growth process. The $CO_2/N_2$ separation in the vacuum mode was investigated at $30^{\circ}C$ for an equimolar $CO_2-N_2$ mixed gas before and after embedding 13X zeolite beads in the permeate side. The embedded 13X zeolite beads improved both $CO_2$ permeance and $CO_2/N_2$ separation factor, simultaneously. The phenomenon was explained by an increment in the $CO_2$ desorption rate at the FAU zeolite/$\alpha-Al_2O_3$ phase boundary due to an enhanced $CO_2$ escaping through the pore channels of the $\alpha-Al_2O_3$ support layer. In the present paper, it will be emphasized that a hybridization of a membrane with an adsorbent can provide a key to break through the trade-off between permeance and separation factor, generally shown in a membrane separation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.1-9
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• 2024

This study proposes a multi-scale template matching technique with image pyramids (TMI) to measure structural dynamic displacement using a vision sensor under atmospheric turbulence conditions and evaluates its displacement measurement performance. To evaluate displacement measurement performance according to distance, the three-story shear structure was designed, and an FHD camera was prepared to measure structural response. The initial measurement distance was set at 10m, and increased with an increment of 10m up to 40m. The atmospheric disturbance was generated using a heating plate under indoor illuminance condition, and the image was distorted by the optical turbulence. Through preliminary experiments, the feasibility of displacement measurement of the feature point-based displacement measurement method and the proposed method during atmospheric disturbances were compared and verified, and the verification results showed a low measurement error rate of the proposed method. As a result of evaluating displacement measurement performance in an atmospheric disturbance environment, there was no significant difference in displacement measurement performance for TMI using an artificial target depending on the presence or absence of atmospheric disturbance. However, when natural targets were used, RMSE increased significantly at shooting distances of 20 m or more, showing the operating limitations of the proposed technique. This indicates that the resolution of the natural target decreases as the shooting distance increases, and image distortion due to atmospheric disturbance causes errors in template image estimation, resulting in a high displacement measurement error.

• Tunnel and Underground Space
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• v.31 no.1
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• pp.41-51
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• 2021

The hydraulic fracturing developed to improve permeability of tight reservoir is one of key stimulation technologies for developing unconventional resources such as shale gas and deep geothermal energy. The experimental study was conducted to improve disadvantage of hydraulic fracturing which has simple fracture pattern and poor fracturing efficiency. The fracturing experiments was conducted for tight rock using various fracturing fluids, water, N2, and CO2 and the created fracture pattern and fracturing efficiency was analyzed depending on fracturing fluids. The borehole pressure increased rapidly and then made fractures for hydraulic fracturing with constant injection rate, however, gas fracturing shows slowly increased pressure and less fracture pressure. The 3D tomography technic was used to generate images of induced fracture using hydraulic and gas fracturing. The stimulated reservoir volume (SRV) was estimated increment of 5.71% (water), 12.72% (N2), and 43.82% (CO2) respectively compared to initial pore volume. In addition, permeability measurement was carried out before and after fracturing experiments and the enhanced permeability by gas fracturing showed higher than hydraulic fracturing. The fracture conductivity was measured by increasing confining stress to consider newly creating fracture and closing induced fracture right after fracturing. When the confining stress was increased from 2MPa to 10MPa, the initial permeability was decreased by 89% (N2) and 50% (CO2) respectively. This study shows that the gas fracturing makes more permeability enhancement and less reduction of induced fracture conductivity than hydraulic fracturing.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.264-269
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• 1996

Four leavels of nitrogen and five split-application method were investigated in the puddled drill seeding of rice in tidal land paddy field of Munpo series in Gyehwado. Soil ammonium concentration increased of higer nitrogen level, and was higher in latex coated urea(LCU) than urea split-application, and stage of $NH_4-N$ was the higher in maximum tillering stage. Rice yield, nitrogen availability and yield increment rate according to nitrogen levels were the highest when nitrogen was applied 200kg/ha and also it were the highest in the LCU application by 30% decreased than urea application as affected by application method. Adequate application amount of nitrogen was estimated 222kg/ha in direct drill seeding of rice in tidal land paddy field.

• Tunnel and Underground Space
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• v.21 no.5
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• pp.394-405
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• 2011

In this paper, we applied coupled non-isothermal, multiphase fluid flow and geomechanical numerical modeling using TOUGH-FLAC coupled analysis to study the complex thermodynamic and geomechanical performance of underground lined rock caverns (LRC) for compressed air energy storage (CAES). Mechanical stress in concrete linings as well as pressure and temperature within a storage cavern were examined during initial and long-term operation of the storage cavern for CAES. Our geomechanical analysis showed that effective stresses could decrease due to air penetration pressure, and tangential tensile stress could develop in the linings as a result of the air pressure exerted on the inner surface of the lining, which would result in tensile fracturing. According to the simulation in which the tensile tangential stresses resulted in radial cracks, increment of linings' permeability and air leakage though the linings, tensile fracturing occurred at the top and at the side wall of the cavern, and the permeability could increase to $5.0{\times}10^{-13}m^2$ from initially prescribed $10{\times}10^{-20}m^2$. However, this air leakage was minor (about 0.02% of the daily air injection rate) and did not significantly impact the overall storage pressure that was kept constant thanks to sufficiently air tight surrounding rocks, which supports the validity of the concrete-lined underground caverns for CAES.

• Journal of the Korean Institute of Gas
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• v.2 no.3
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• pp.37-48
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• 1998

A cryogenic liquid stored in the closed cryogenic tank has been studied at various liquid levels. The change of pressure, temperature, and liquid-vapor ratio in the tank depended on the liquid levels. The various phenomena were shown at different liquid levels as follows: (1) liquid level was increased with condensation of vapor: (2) liquid was vaporized in spite of liquid level going up for a certain initial period and then condensation of vapor occurred at higher pressure; (3) liquid was vaporized without liquid level change; (4) liquid was vaporized with liquid level decreasing. If the tank is full with cryogenic liquid, it is extremely dangerous because of soaring the pressure. Therefore the tank must be filled with $90\%$ liquid according to the safety rules. If the tank was filled with $0\%$ ullage, the pressure increment as high as 80bar during first 5 days. With $90\%$ liquid level, however, the pressure was increased as low as 1.5bar in the same period. No matter what the liquid level is, it is very dangerous if the tank is locked-up with filled cryogenic liquid for a long time.

• Korean Journal of Medicinal Crop Science
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• v.5 no.2
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• pp.91-94
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• 1997

This experiment was carried out to investigate the effects of black P.E. film mulching by different sowing dates on the growth and yield of Achyranthes japonia NAKAI. Emergence rate and the growth increment were increased in black polyethylene (P.E.) film mulching of sowing date at April 1. Dried root yield was highest by 3,190kg/ha in black P.E. film mulching and earlist sowing at April 1 with 20% increase compared to that of non mulching at April 1 planting.