• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1522-1529
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• 2009

When a shaft is excavated in Korea, the mechanized method such as RBM(Raise Boring Machine) or RC(Raise Climber) is used independently of depth. But usually, the mechanized method is useful for the deep depth. On the contrary, when the depth of shaft is short, the cost of excavation increase. So in the case of shaft constructon less than 100m, we need to consider more suitable method of shaft construction such as Stage-cut which is one of blasting methods. Stage-Cut is widely used in the field of shaft construction in Japan as a tool of rock excavation. The main purpose of this study is to provide technical guidance for design and construction of shafts in rock, using Stage-cut method which is suitable for 20m~80m depth shaft. In this study, Blasting tests was performed in field, according to rock classification. Finally, the stage-cut method which is suitable for the geology of Korea was developed.

• Explosives and Blasting
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• v.25 no.1
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• pp.31-43
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• 2007

In most tunnel constructions in South Korea, blasting has been widely used as an excavation method. In tunnel blasting, the center-cut to induce first free surface is very important for enhancing excavation efficiency and reducing vibration caused by exploding. This paper introduces new center-cut method named SAV-cut (Stage Advance V-cut) developed on the concept of V-cut. Significant features of SAV-cut are the center hole and stepwise ignition. Many field tests and numerical analysis were carried out to analyze the mechanical behavior and blasting vibration. From the results, the newly developed SAV-cut was proved as an effective center-cut method for both increasing blasting efficiency and decreasing blasting vibration.

• Journal of the Korean Society of Tobacco Science
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• v.25 no.1
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• pp.34-38
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• 2003

This study was carried out to investigate the changes of dehydration process and quality of cured leaves with crushed midribs and cut of the yellowed leaves during drying stage of flue-cured tobacco. The crushed midribs of yellowed leaf dried out before raising the highest temperature of midrib drying stage and reduced the curing time by about 20 hours. However, the cut of yellowed leaf was not affected the curing time and dehydration process during drying stage of flue-curing due to a problem with the cut leaves packing excessively in the curing container. The cured weight yield was increased with crushed midrib and cut leaves, and nicotine and sugar contents of cured leaves and quality in terms of dollars per kilogram were decreased with crushed midrib and cut leaves.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.2
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• pp.121-128
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• 1991

Forage productivity of two sorghum hybrids, Pioneer(P) 931 and P 956 and a sorghum-sudangrass hybrid, P 988, was studied. The 1st-cut of sorghun hybrids was made for silage 6 times from heading stage at a week-interval and regrowth (2nd-cut) was harvested on Oct. 13 although plants were not reached the same growth stage of 1st-cut. However, the 1st- and 2nd-cut of sorghum-sudangrass were made for green fodder 6 times from 4 weeks before heading stage at a week-interval. 1. Percent dry matter(DM) of 1st-cut of sorghum and 1st- and 2nd-cut of sorghum-sudangrass increased as growth stage advanced. Percent DM of 2nd-cut of sorghum decreased as the 1st-cut date delayed due to insufficient growing period on Oct. 13. 2. In the 1st-cut of sorghum the proportion of leaf blade (LB) or culm+leaf sheath (LS) to total DM decreased, but that of panicle increased as growth stage advanced. The panicle proportion of P 956 increased and culm+LS decreased more rapidly compared with those of P 931. IIowever, in sorghum-sudangrass hybrid the proportion of LB decreased and culmf LS increased as growth stage advanced through heading stage. 3. In the 1st-cut of sorghum hybrids crude(C) protein and C. fiber decreased, but nitrogen free extract (NFE) increased as growth stage advanced although C. fat and C. ash were similar among the growth stages. In the 2nd-cut of sorghum C. protein and C. ash increased, but NFE decreased as harvesting date delayed due to plants were younger although C. fat and C. fiber were similar among the harvesting dates. In the sorghum-sudangrass C. protein of 1st-cut decreased, but C. fiber of 1st-cut and NFE of the 1st-and 2nd-cut increased as growth stage advanced. 4. DM yield of 1st-cut of sorghum increased from heading stage to 3 weeks after heading and then levelled off, but total DM including regrowth was similar among the harvesting time. In the sorghum-sudangrass hybrid DM yield of 1st-cut and total DM yield including 2nd-and 3rd-cut increased as the harvestingtime delayed.

• FLOWER RESEARCH JOURNAL
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• v.18 no.4
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• pp.231-237
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• 2010

This study was conducted to improve commercial quality of a cut spray chrysanthemum 'Ilweol' bred in Korea by foliar application of daminozide, suppressing excessive elongation of peduncle caused by high temperature in summer season production. Applications were made at three floral bud developmental stage (I, II, and III), and concentrations used were 0, 500, 1000, and $2000mg{\cdot}L^{-1}$. Cut flower length and peduncle length showed the greatest repression of elongation through daminozide treatments at stage III and stage II, respectively. Daminozide also gradually reduced values of those in a concentration-dependant manner. Flower diameter increased compared to control as daminozide was sprayed at later stage but decreased in daminozide concentration-dependant manner. Angle of flower cluster on apical part of whole plant showed the best results when sprayed with $2,000mg{\cdot}L^{-1}$ at stage III. Among all combinations, $2,000mg{\cdot}L^{-1}$ daminozide at stage II recorded the highest angle of flower cluster and showed 31.3% increment as compared to control. The number of fully expanded flowers showed the highest values using $2,000mg{\cdot}L^{-1}$ daminozide at stage III than the other treatments and total floral buds also showed the highest values using $2,000mg{\cdot}L^{-1}$ daminozide at stage I than the other treatments. In cut spray chrysanthemum cultivar 'Ilweol' bred in Korea, foliar-applying with $2,000mg{\cdot}L^{-1}$ at stage III most effectively suppressed excessive peduncle elongation, angle of flower cluster, and increased the number of flowers in summer. However, this combination affected negatively the other commercial qualities, reducing cut flower length and flower diameter. Therefore, we recommended that foliar application stage and daminozide concentration was stage III and $500mg{\cdot}L^{-1}$, respectively, in a practical culture and cut flower quality for 'Ilweol'.

• Membrane Journal
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• v.26 no.2
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• pp.159-165
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• 2016

Polyimide hollow fiber membrane modules were prepared in order to investigate the process of multi stage gas separation. The modules performance was carried out using 50/50 of $N_2/SF_6$ mixed gas. The membrane modules has been tested for measuring gas flow rate and concentration under various stage cut at 0.5 MPa. The membrane modules showed a high recovery ratio at the same stage cut as $N_2/SF_6$ selectivity increased. Two stage process was fulfilled for improving $SF_6$ recovery ratio and $SF_6$ concentration. Eventually, two stage process showed higher performance of $SF_6$ recovery ratio and concentration ($SF_6$ recovery ratio = 95%, $SF_6$ conc. = 98%).

• Membrane Journal
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• v.22 no.4
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• pp.251-257
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• 2012

For the separation and recovery of n-pentane from nitrogen environment, the poly (dimethyl siloxane) (PDMS) composite membranes supported by polyetherimide (PEI) hollow fiber membranes were prepared. To characterize the gas separation properties of the resulting membranes, the permeance of n-pentane and nitrogen, concentrations of permeate and retentate, and recovery ratio were measured for n-pentane and nitrogen mixtures. The permeance of n-pentane and nitrogen, 2485.3 and 9.9 GPU, were observed respectively. As the stage cut decreases and the feed concentration increases, the n-pentane concentration in permeate tends to increase. In the meanwhile, the recovery efficiency tends to increase as the stage cut increases and the feed concentration decreases.

• Membrane Journal
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• v.22 no.1
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• pp.54-61
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• 2012

To separate and recover of VOCs, supporting membranes using PEI were prepared by phase separation method and it was coated with PDMS to prepare PEI-PDMS hollow composite membrane. To investigate characteristic of prepared membrane, pure gas permeability was measured using oxygen and nitrogen, the stage cut and permeance property with feed concentration were evaluated using xylene, ethyl benzene, toluene and cyclohexane. Also, to check solvent resistance on VOCs, stress-strain property of membrane with immersion time in solvent were measured by DMA. The permeance value of $O_2$ and $N_2$ showed 63 GPU and 30 GPU respectively. Permeated VOCs concentration was decreased with increasing stage cut. But, conversely, recovery efficiency that was increased with increasing stage cut. As a result of DMA test, the stress and strain were 11.93 MPa and 13.52%, respectively.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.573-579
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• 2013

This study was conducted to investigate optimal harvesting stage and the effects on cut roses of Korean cultivar harvested at different stages. Cut roses are harvested at three different flowering stages. The optimal harvesting stage of cut roses was different depending on varieties. The vase life of standard type 'Pink Song' and spray type 'Peace One' was extended when they were harvested in one and three stages, respectively. The vase life was generally increased when the cut roses were pretreated with a solution containing 2% sucrose + $200mg{\cdot}L^{-1}$ aluminum sulfate + $200mg{\cdot}L^{-1}$ $Mg(NO_3)_2$ + $50mg{\cdot}L^{-1}$ $CaCl_2$ as compared to the control regardless of the harvesting stage. And this pretreatment solution improved the flower quality of cut roses bred in Korea. But the effects of pretreatment were varied depending on the harvesting stage.

• FLOWER RESEARCH JOURNAL
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• v.17 no.2
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• pp.121-127
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• 2009

This study was conducted to improve commercial quality of a cut spray chrysanthemum 'Gama' bred in Korea by foliar application of daminozide (DMZ), suppressing excessive elongation of peduncle caused by high temperature in summer season production. Applications were made at three floral bud developmental stages (I, II, and III), and concentrations used were 0, 500, 1000, and $2000mg{\cdot}L^{-1}$. Both cut flower length and peduncle length showed the greatest suppression of elongation by DMZ treatments at stage II. DMZ also gradually reduced values of those in a concentration-dependant manner. Stem thickness and flower diameter reduced compared to control as DMZ was sprayed at later stage and those two characteristics decreased in a concentration-dependant manner. The number of paralleled flowers neighboring apical part of whole plant showed the best results at stage I and II. As for DMZ concentration, those increased effectively at $500-1,000mg{\cdot}L^{-1}$. Among all combinations, $1,000mg{\cdot}L^{-1}$ DMZ at stage II recorded the most paralleled flowers and showed 24.2% increment as compared to control. The number of fully expanded flowers and total floral buds also showed the highest values using $1,000mg{\cdot}L^{-1}$ DMZ at stage II than the other treatments. In cut spray chrysanthemum cultivar 'Gama' bred in Korea, foliar-spraying with $1,000mg{\cdot}L^{-1}$ DMZ at stage II most effectively suppressed excessive peduncle elongation, parallelled flower cluster arrangement, and increased the number of flowers in summer. However, this combination affected negatively the other commercial qualities, reducing cut flower length, stem thickness, and flower diameter. Therefore, we recommended that foliar-spraying stage and DMZ concentration was stage I and $1,000mg{\cdot}L^{-1}$, respectively, in a practical culture for 'Gama'.