• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.41-44
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• 1977

Production of haploids in vitro anther culture of Nicotiana tabacum L. was oriented in a large number on a chemically defined culture medium. The haploids were screened for T.M.V. resistance and the segregating ratio in F$_1$ were in good agreement with the expected ratio.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.117-124
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• 2017

In this study, to evaluate the setting time, compressive strength and drying shrinkage of ordinary Portland cement and Portland blast-furnace slag cement mortar with 0, 10, 20, 30 wt.% alpha-calcium sulfate hemihydrate. As a results, as the replacement ratio of alpha-calcium sulfate hemihydrate increased, the initial setting time of ordinary Portland cement and Portland blast-furnace slag cement mortar was faster. In addition, the compressive strength decreased with increasing replacement ratio of alpha-calcium sulfate hemihydrate in both ordinary Portland cement mortar and Portland blast-furnace slag cement mortar. The strength development of Portland blast-furnace slag cement mortar with alpha-calcium sulfate hemihydrate was effective than that of ordinary Portland cement mortar. On the other hand, in the case of the mortar with alpha-calcium sulfate hemihydrate, it was confirmed that shrinkage deformation was reduced at the early age by growth pressure of needle-shaped ettringite crystals produced by incorporation of alpha-calcium sulfate hemihydrate. However, the effect of inhibiting shrinkage deformation of mortar with alpha-calcium sulfate hemihydrate was not significant as the age passed. Therefore, it is considered that the alpha-calcium sulfate hemihydrate is useful as a construction material.

• Korean Journal of Heritage: History & Science
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• v.45 no.3
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• pp.238-261
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• 2012

This research was carried out about the Bansu which surrounded the Sunggyungwan(成均館), national university in the Joseon Dynasty to get the main characteristics of the landscape at Korean traditional school campus by analyzing cultural meaning and historical origin. The earliest record about the Bansu was in "The Book of Odes(詩經)" as Bansu was the water flowing near the Ban palace(泮宮). But, in the following time, Bansu has become the symbol of the school which was built by the feudal lords and one of very important elements in the temple-school(廟學) landscape. The Bansu of Sunggyungwan at Joseon Dynasty was the streams flowing at the east and west of the school campus and get together at the south. Sunggyungwan was located in the sacred place which followed the special organization of Bansu at the beginning of the Joseon Dynasty. And, Bansu in Joseon Dynasty was influenced by the Bansu in Song Dynasty(宋), but it was different from the Bansu in Ming and Qing Dynasty which has been formulated as the halfround pond in front of the school. This research tried to find the reason why in the Josenon Dynasty the stream flowing around the school was regarded as the Bansu. Bansu was also regarded as an important element in the public school, Hyanggyo(鄕校) and the private Seowon(書院). According to this research, the streams which flows around the Seowon or the Hyanggyo were found as called Bansu. Water stream around the Hyanggyo and the Seowon in the Joseon Dynasty has to be reconsidered under the deep research on the organization of Ban-su.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.237-241
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• 2006

This experiment was carried out comparison with haploid plants productivity by microspore culture among domestic cultivars of Brassica napus L. Isolated microspore from flower buds were cultured on NLN medium supplemented with 13% sucrose, $0.05mg/{\ell}$ BA and $0.5mg/{\ell}$ NAA. Genotype was important factor in haploid embryo productivity 'Tamlayuchae' showed the highest haploid embryo production frequency (176 embryos formed from 1 flower bud). But, 'Hallayuchae' and 'Youngsanyuchae' were not generated embryo even cell division. When suspension culture on NLN liquid medium at 100 rpm, embryos were developed multilobe abnormal embryo cluster. Multilobe abnormal embryos on MS medium basal solid medium were regenerated multiple shoots. Regenerated haploid plant with well developed shoots and roots on MS basal medium were successfully transferred to pots.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.6
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• pp.533-538
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• 2007

A semi-passive vibration isolation control method for enhancing pointing performance of on-board payload has been derived, and its effectiveness has been evaluated through numerical simulation. The semi-passive control law proposed in this study was derived so as to obtain the same performance as a high passive damping at low frequencies and obtain the same performance as a passive low damping at high frequencies. In the numerical simulation, the intended vibration isolation performance of the semi-passive control law has been obtained.

• Korean Journal of Social Welfare Studies
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• v.47 no.4
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• pp.183-216
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• 2016

This study aims to investigate the career development experience of youth in late adolescence who entered a different university after taking a semester off (as known as Bansu in Korean), in depth, applying a phenomenological research method. For the research, this study selected seven adolescents as research participants to reveal the essential meaning of their experience, vividly. The data were analyzed by Giorgi's method to draw components of the experience of research participants. As a result of the research, the career development experience of youth in late adolescence who entered a different university after taking a semester off was systematized into 19 sub-categories and structured into four main categories: "high school years in which academic record was more important than aptitude", "the step away from the dream, being forced to proceed to college", "the time of study to take the exam again, which was an advantage and disadvantage at the same time" and "the wish unfulfilled even with the success of entering a different university." It turned out that the main topic was "the repeated way even after passing the repeat sign." They took the College Scholastic Ability Test (CSAT) once again and came back to the narrow way to enter a prestigious university, but they still compromised the standard made by the older generation. This study has significance for late adolescents' welfare and happiness in that it explored the in-depth meanings of the career development experience of youth who entered a different university by taking the CSAT again after taking a semester off. Lastly, based upon the situation of the increase in the number of students who take the CSAT again, this study suggested better measures for career development during adolescence and the promotion of their quality of life.

• Korean Journal of Plant Tissue Culture
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• v.21 no.6
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• pp.333-339
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• 1994

Enzyme activities and phenolic compound were compared to investigate the physiological characteristics during shoot formation from diploid and haploid of Nicotiana tabacum w BY4. The Nakata medium with 1.0 mg/L IAA, 0.5 mg/L Kinetin and 3 g/L activie carbon was excellent to induce the haploid plants from the middle size anther within 30 days after culture. The MS medium with 0.5 mg/L 2,4-D was good for callus induction from leaf explants of diploid and haploid, and a lot of plane were regenerated from calli on the MS medium supplemented with 2.0 mg/L BAE Activities of peroxidase for both of diploid and haploid plane were the highest at 2.0mg/L BAP Activities of IAA oxidase and catalase of haploid Plants were high or than those of diploid plants. On the other hand, activity of peroxidase of haploid plants were lower than those of diploid plants.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.1-7
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• 2019

This study evaluated the mechanical properties of the alpha-calcium sulfate hemihydrate replaced concrete to reduce the cracking in a box culvert power transmission. After setting the replacement ratio of alpha-calcium sulfate hemihydrate at 0, 6, 9, 12, and 15%, the setting time, compressive strength, and drying shrinkage were measured and the microstructure and crystal structure were analyzed. As a result, it was confirmed that as the replacement ratio of alpha-calcium sulfate hemihydrate increased, the setting time decreased and the compressive strength declined. On the other hand, when the alpha-calcium sulfate hemihydrate was set with 15% of replacement ratio, about 60% reduction in the drying shrinkage was shown compared to that of ordinary Portland cement. Therefore, it is thought that when the concrete replacing the alpha-calcium sulfate hemihydrate is applied to a box culvert power transmission, the cracking reduction performance will be improved, and the improvement of compressive strength will be required.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.72-79
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• 2019

Concrete is vulnerable to cracks due to volume changes caused by temperature changes, shrinkage during curing, external forces, or poor construction. In particular, concrete placed in electric power tunnel structures can generate cracks by a variety of factors. As a result, these tunnel structures require continuous maintenance. In this study, we investigated the mechanical properties of electric power tunnel concrete using alpha-calcium sulfate hemihydrate, which is an industrial byproduct that has excellent expansion performance. To compensate for the decrease in compressive strength when substituting alpha-calcium sulfate hemihydrate, based on previous research, we added 9% alpha-calcium sulfate hemihydrate and adjusted the amount of admixture while using the same amount of cement. We then evaluated the mechanical properties of the concrete. The results showed that the compressive strength of the concrete was higher than that of ordinary Portland cement (OPC), and the shrinkage of concrete was reduced by more than 30% compared to that of OPC. Therefore, adding 9% of alpha-calcium sulfate hemihydrate is expected to have a significant effect in reducing concrete cracks.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.25-32
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• 2024

In this study, the mechanical properties of PHC pile concrete using alpha-type hemihydrate gypsum were evaluated. As the replacement ratio of alpha-type hemihydrate gypsum increased, the setting time rapidly accelerated. In particular, when replacement ratio exceeded 20 %, the setting time was shortened due to rapid hydration reaction, making it impossible to secure working time. As the replacement ratio of alpha-type hemihydrate gypsum increased, the ettringite and gypsum peaks tended to increase, and it is believed that the shrinkage of concrete decreased due to the increase in the ettringite peak. At a As the replacement ratio of 5 to 15 % for alpha-type hemihydrate gypsum, the compressive strength increased or was found to be equivalent to that of OPC. But at 20 % substitution, workability deteriorated due to rapid setting, so use of the 5 to 15 % range is considered appropriate.