• Journal of Plant Biotechnology
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• v.31 no.3
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• pp.209-217
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• 2004

The shoots of balloon flower (Platycodon grandiflorum A. DC.) in vitro germinated from seeds were cultured on MS basal medium containing 0.1 mg/L NAA under the various sucrose concentrations and with/without membrane filter (MF) on the lid of vessel. The growth responses were checked to obtain healthy plantlets. The $CO_2$ and $C_2$H$_4$ concentration in vessel without MF were higher than those with MF. The $CO_2$ concentration without MF was increased as days in culture went by whereas the $C_2$H$_4$ concentration was decreased. The plant growth with MF and high sucrose concentration was good. Fresh and dry weight of plantlets cultured in sucrose 4.5% with MF were higher than those in no sucrose without MF. Also the content of chlorophyll of plantlets cultured with MF was high and the content of sugar was shown a similar results and a remarkable difference between MF treatments, especially. Stomata cultured with MF was closer than that without MF and mesophyll of leaf were more developed with MF or in high sucrose concentration. When the plantlets were transplanted in the pot at 25$\pm$2$^{\circ}C$, 75% relative humidity and low PPFD (photosynthetic photon flux density), the percentage of survival after 13 days without MF was 0% but it was 100% with MF regardless of sucrose concentrations.

• Korean Journal of Plant Resources
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• v.15 no.1
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• pp.72-76
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• 2002

This study was carried out to determine an effective mechanical harvester for rhizomes of Rehmannia glutinosa Libosch. Labor-saving efficiency showed 69∼76% by using tillage operations with power tiller, digger attached to power tiller, and digger attached to tractor compared with manual harvest. Loss percentage of rhizomes by mechanical harvesters was 3.1∼ 9.3% higher, and fresh rhizome yield was 2∼6％ lower than that by manual harvest, respectively. Although it showed higher loss percentage of rhizomes and lower fresh rhizome yield compared with manual harvest, mechanical harvest using digger attached to power tiller or digger attached to tractor was effective in labor-saving for rhizomes of Rehmannia glutinosa Libosch.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.102-109
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• 2010

This paper investigates the bond behavior of reinforced concrete beams having high-strength transverse reinforcement. A total of four reinforced concrete beams were tested in this study to estimate the bond capacity of the proposed U-shape reinforcement. The proposed U-shape reinforcement not only has a simple structure to install, but also can increase the bond capacity of reinforced concrete beams by controling bond cracks. This study follow the test method proposed by Ichinose to obtain the bond stress and the bond slip of the specimens. The main test parameters were the yield strength, ratio, and reinforcing types of transverse reinforcements. It was found that the proposed U-shape reinforcement was able to effectively improve the bond performance of reinforced concrete beams with high-strength transverse reinforcement.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.154-162
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• 2022

In this study, data on the types and density of abalone attached organisms were provided in marine net cage of the southern coast. In addition, the effect of the removal of attached organisms was evaluated. In marine net cage, oysters, bryozoa, and barnacles were dominated among the attached organisms, and their average area ratio was about 57.5%. The growth rate and hepatopancreas condition were better in removal group of attached organisms than control group. Therefore, it is judged that the removal of attached organisms from abalone is necessary for the growth of individuals and improvement of value.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.89-90
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• 2010

Three post-tensioned lightweight concrete beams were tested to examine the effect of the reinforcement index on the unbonded tendon stress at ultimate strength of the beams. The reinforcement index selected for main variables were 0.06, 0.15, 0.30. Test results showed that the stress of the unbonded tendons in the ultimate strength of the post-tensioned lightweight concrete beams can be conservatively evaluated using the empirical equations specified in ACI 318-08.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.61-69
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• 2010

Unbonded precast concrete piers have better seismic performances than conventional reinforced concrete piers. In this research, seismic performances of unbonded precast prestressed concrete piers are analyzed using OpenSEES. Main parameters of analysis are concrete strength, jacking force ratio, ratio of tendon, and size of precast segment. In results, as the ratio of tendon and jacking force ratio increase, the flexural strength increases at softening state and ultimate state. Concrete strength and size of precast segment are negligible. But initial jacking force ratio leads to early yielding of prestressing tendon. Since compressive strain in core concrete is much less than ultimate strain, it can be expected that the amount of transverse steel reinforcement is to be reduced in comparison with conventional reinforced concrete column.

• Journal of Aquaculture
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• v.18 no.3
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• pp.142-146
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• 2005

In this study, the reattachment processes of small and medium size of spot of Mytilus coruscus and M. edulis were observed. The small spats (Shell length, SH, $3{\sim}7mm$) of hard shelled mussel, M. coruscus showed 100% reattachment rate within 7 minutes after the detachment of byssus thread and 100% survival rate. While large spats (SH 25 mm) showed 85% reattachment rate within 5 hours and 100% survival rate for 24 hours. The reattachment rate of M. edulis (SH 30 mm) was higher than that of M. coruscus (SH, 28 mm). The thread consisted of three identifiable structures; adhesive disc, adhesive thread and adhesive root. The adhesive disk and adhesive thread of M. coruscus were larger and thicker than those of M. edulis, whereas the thickness of adhesive root was the other way round. Further studies are required to identify the relationship between the structure of byssus thread and attachment ability. This study suggests that the sizes of spats could be an important factor in determining the timing of removing and reattaching mussel seedling for aquaculture or releasing to the sea.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.417-418
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• 2003

섬유제품을 착용하면, 땀ㆍ피지ㆍ때 등 피부로부터 대사 노폐물이 섬유표면에 부착되고, 의복이 오염되어 비위생적이 된다. 오염물이 부착된 섬유제품에서는 악취가 발생함과 더불어, 보온성이나 통기성이 저하하기 때문에 착용감이 나빠진다. 피부에 상존하는 세균이나 외부로부터 부착된 미생물은 섬유에 부착된 인간의 노폐물이나 오염물질 등의 유기화합물을 소화시켜 휘발성 악취물질을 발생한다.$^{1)}$ 항균 방취 가공은 미생물의 부착과 번식을 억제하고 나아가서 불쾌감을 없애주는 기술이다. (중략)

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.569-577
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• 2021

CFRP(Carbon Fiber Reinforced Plastic) can maintain the same strength even if the diameter is reduced by about one - third, and the weight is about one - twentieth of that of the deformed reinforcing bars that have been used in the construction industry. In particular, it is resistant to corrosion, which is the weakest part of reinf orcing bars, and there is no concern that it will deteriorate over time, It is light and durable, so transportation costs are low and it is convenient for high-rise buildings. This paper experimentally clarifies the adhesive properties of CFRP and clarifies its behavior. That is, bond strength test was conducted with the directness of CFRP and the strength of concrete as experimental variables, and the bond mechanism was clarified experimentally. Furthermore, based on the experimental results, we constructed the bond stress-slip-strain relationship of CFRP compared to the existing deformed reinforcing bars.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.169-178
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• 1998

Bond strength of reinforcing bar to high-perfomance concrete using belite cement is explored using beam end test specimens. The key parameters for the bond test are slump of concrete, top bar effect, and strength of concrete in addition to concrete cover. The test results show that the specimens with belite cement concrete show approximately 10% higer bond strength than those with portland cement concrete. The results also show that the bond strength from the high strength concrete is function of the square root of concrete compressive strength. Bond strength of the top bar is less than bond strength of bottom bar, but the ratios of the bond strength of bottom-cast bars to those for top-cast bars are much less than the modification factor for top reinforcement found in the ACI 318-95 code. Comparisons with other reported tests identified that belite cement increased bond strength while silica fume or flyash used in high strength concrete decreased bond strength. The high-strength and high-slump concrete with belite cement performs well in terms of bond strength to reinforcing steel.