• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.191-196
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• 1998

Under concentrational paste and dilute suspension systems, we have been tested the effects in the dosage of two superplasticizers [naphtalenic(NSF) and polycarboxylic(NT-2)] which has been varied from 0 to 2.0 wt%, in both one case of cement Ⅱ-anhydrite and fly ash itself and the other case that cement has been substituted 10wt% to Ⅱ-anhydrite and fly ash. The result of tested zeta potential tells that zeta potential values increase in addition to increasing of the NSF dosage. And it's effect was high in case of fly ash. We has confirmed the 10wt% substitution of Ⅱ -anhydrite and fly ash would be more effective than the cement itself in initial fluidity and stable fluidity. And in case of NT-2 and NSF, addition of 1.0wt% NT-2 improved the fluidity of paste cement more than that for NSF.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.57-58
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• 2023

This study was proceeded to analyze thixotropy of cement paste according to the addition timing of PVA and borax as a basic study of thixotropy of concrete. According to experiment results, the case added borax first and PVA later is that cement paste shows low thixotorpy, and the case added PVA first and borax later is that cement paste shows thixotropy but in certain mix condition fluidity of decrease due to a chemical bond between PVA and borax. The case add PVA and borax simultaneously is that cement paste was expressed thixotropy in all mix condition. Therefore the case add PVA and borax simultaneously is suitable for expressing thixotropy of cement paste.

• Journal of Chest Surgery
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• v.6 no.2
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• pp.175-180
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• 1973

Aneurysmal bone cysts of rib continue to interest the clinicians because of their rarity. We experienced a case of aneurysmal bone cyst of Rt 10th rib, which was occupying the Rt pleural cavity as a huge mass. This case was treated surgically with good result. In addition, general concept of aneurysmal bone cyst with brief review of literatures was disclosed here.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.75-81
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• 2006

Lean premixed combustion is a well known method for low $NO_x$ gas turbine combustor. But lean combustion is usually accompanied by flame instability. To overcome this problem, the hydrogen ($H_2$) was added to main fuel methane to increase flammable limit. In this paper, the effects of hydrogen addition on lean premixed combustion of methane ($CH_4$) were investigated numerically. Results showed that the extinction stretch rate increases and the extinction temperature constant with relatively small amount of $H_2$ addition. The flame temperature and NO emission increase with $H_2$ addition at the same stretch rate and equivalence ratio but it could increase the range of lean extinction and extinction equivalence ratio limit. Eventually, the $H_2$ addition case showed almost same or lower NO emission than no addictive $CH_4$ case in the extinction condition.

• Journal of the Korean Ceramic Society
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• v.20 no.3
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• pp.193-198
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• 1983

This experiment has been carried out for the purpose of investigating the effect of $V_2O_5$ and $H_3BO_3$ additives on sintering of magnesium oxide over the temperature range of 1300-150$0^{\circ}C$ MgO powder has been obtained by calcin-ing extra reagent grade magnesium carbonate(basic) at 90$0^{\circ}C$ for 30 minutes. The specimens were prepared by compression with pressure of 700Kg/cm2 then fired at 1300-150$0^{\circ}C$ for 0-5hrs. Sintering behaviour and microstructure of fired specimens were examined. Densification rates obeyed the equation D=K 1n t+C. The ratio of density in case of addition of $V_2O_5$ to theoretical density of pure periclase was 95-99% Activation energy of densification in case of $V_2O_5$ addition was 30.15 Kcal/mole. The range of average grain size in case of addition of $V_2O_5$ was 40-50$\mu\textrm{m}$. $H_3BO_3$ addtivie had not an effect on densification of MgO.

• Language and Information
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• v.19 no.1
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• pp.1-18
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• 2015

Korean marks case for subjects and objects, but it is well known that case-markers can be dropped in certain contexts. Kwon and Zribi-Hertz (2008) establishes the phenomenon of Korean case drop on a single factor of f(ocus)-structure visibility and claims that both subject and object case drop can fall under a single linguistic generalization of information structure. However, the supporting data is not empirically substantiated and the tenability of the f-structure analysis is still under question. In this paper, an experiment was conducted to show that the specific claims of Kwon and Zribi-Hertz's analysis that places exclusive importance on information structure cannot be adequately supported by empirical evidence. In addition, the present study examines H. Lee's (2006a, 2006c) multi-factor analysis of object case drop and investigates whether this approach can subsume both subject and object case drop under a unified analysis. The present findings indicate that the multi-factor analysis that involves the interaction of independent factors (Focus, Animacy, and Definiteness) is also compatible with subject case drop, and that judgments on case drop are not categorical but form gradient statistical preferences.

• Journal of environmental and Sanitary engineering
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• v.12 no.2
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• pp.75-81
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• 1997

The study was investigated with denitrification of wastewater containing nitrate using upflow anaerobic sludge blanket process. Contents of this study were the determination of nitrate removal efficiency by various hydrogen donor addition, relationship between HRT, nitrate loading rate and growth constant of microorganism in case or various hydrogen donor addition etc. Results from this study were summurized as follows. In case of adding methanol, ethanol, sodium acetate as hydrogen donor, treatability of wastewater contained 200mg/l as nitrate was about 91%. But in addition of ethanol, sodium acetate in wastewater contained 40mg/l as nitrate, nitrate removal efficiency was 80%. While the treatment of nitrate showed the yield coefficient of microorganisms(Y) as 234.8, 234.35, and 247.68 g/VSS/g nitrate, respectively, showed specific growth rate(K) as 0.885, 0.934 and 0.917 respectively.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.1
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• pp.141-150
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• 2021

Purpose : The purpose of this study was to investigate the effect of case-based learning application in human growth development classes on nursing students' problem-solving ability, self-directed learning ability, and academic self-efficacy. Methods : The research method was a self-report questionnaire before and after case-based learning for second-year nursing students who took the human growth development course at U University in K city. The collected data were statistically processed using SPSS WIN 21.0. Results : The results of the study showed that after case-based learning, problem-solving ability, self-directed learning ability, and academic self-efficacy were all significantly improved. In addition, as a result of examining the correlation between each variable after case-based learning, problem solving ability score and self-directed learning ability score (r=.54, ｐ<.01), and problem solving ability scores and academic self-efficacy scores (r=.44, ｐ<.01), were significantly correlated with self-directed learning ability scores and the academic self-efficacy reduction scores (r=.76, ｐ<.01). Conclusion : The results of this study suggested the need for various learning programs such as case-based learning to improve nursing students' problem-solving abilities and self-directed learning abilities and their application. In addition, to improve the learning self-efficacy of nursing students, a continuous and systematic study is suggested to develop and apply customized educational programs according to the learners' preferences. Since the sample group in this study was limited to one university, there were few cases and no control group, so there are limitations in generalizing the test effect, However, significant differences a were verified in the case-based learning pre-tests and post-tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.16-21
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• 2017

The aim of this study was to utilize ferronickel slag produced in the manufacture of stainless steel as a flowable backfill material for underground use using crushed fine powder. Experimental combinations were made using two components: Case A (sand) and Case B (soil). The optimal mixing ratio of Case A was sand (58.4%), ferronickel slag fine powder (21.6%), cement (1.8%), and water (18.2%). In the case of B, the optimal mixing ratio was determined to be soil (53.0%), ferronickel slag fine powder (20.0%), cement (1.7%), and water (25.3%). The uniaxial compressive strength of case A, which is a mixture of ordinary sand and ferronickel slag powder, was relatively larger than that of case B using soil. In addition, the strength of the specimen increased with increasing curing time. The uniaxial compressive strength tended to increase with increasing curing time. In addition, the unconfined compression strength of the fluid backfill material using common sand as the main material was relatively larger than that of the mixed material using soil as the main material. In case A, the uniaxial compressive strength ranged from 0.17-0.33 MPa, 0.21-0.39 MPa, and 0.19-0.40 MPa, respectively, at curing times of 7, 14, and 28 days. From the experimental results, it was concluded that the ratio of FNS powder and cement mixture was the most appropriate for Case A3. Case B, which used soil as the main material, showed a similar tendency to Case A. As a result of the dissolution test for evaluating the environmental harm of the FNS fine powder, there was no dissolution of substances harmful to the environment.

• Journal of the Korean Wood Science and Technology
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• v.12 no.4
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• pp.19-30
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• 1984

This experiment was carried out to investigate the effects of autohydrolysis and extraction conditions on the separation of the chemical substances, the extractability of lignin by dioxane, and the yield of reducing sugars from cellulosic substrates by using a commercial cellulase derived from Trichoderma viride. Air-dried wood meals through 0.42mm (40 mesh) screen and retained on 0.25 mm (60 mesh) of Populus alba-glandulosa and Pinus koraiensis were autohydrolyzed with water at $180^{\circ}C$ for 30 and/or 60 minutes in a 6 liter stainless-steel digester with or without 2% 2-naphthol. The hydrothermally-treated wood meals were extracted the lignin with 100%, 90%, 75% and 50% dioxane solutions at $70^{\circ}C$ for 4 hours, respectively. The results obtained were as follows; 1) After autohydrolysis of Populus alba-glandulosa, the yield of wood meals decreased with lengthening the auto hydrolysis time from 30 minutes to 60 minutes and with 2% 2-naphthol addition. In case of Pinus koraiensis, the yield was not affected by 2%, 2-naphthol addition at the autohydrolysis in the digester. 2) After autohydrolysis and lignin extraction of Populus alba-glandulosa, the yield of wood meals decreased with lengthening the autohydrolysis time from 30 minutes to 60 minutes and with 2% 2-naphthol addition. Extraction of 50% dioxane solution was the best solvent for the yield among the solutions of 100%, 90%. 75% and 50% dioxane. In case of Pinus koraiensis, the yield was not affected by 2% 2-naphthol addition and the solution of 90% dioxane was the poorest solvent for the yield. 3) After autohydrolysis and lignin extraction of Populus alba-glandulosa, the Klason lignin content in cellulosic substrates for enzymatic hydrolysis decreased with lengthening the autohydrolysis time from 30 minutes to 60 minutes and with 2% 2-naphthol addition. Klason lignin content was the lowest after extraction by 90% or 75% dioxane solution. The content was also affected by interaction of the three factors-autohydrolysis time, 2% 2-naphthol addition and concentration of dioxane. In case of Pinus koraiensis, the Klason lignin content increased with 2% 2-naphthol addition but was not affected by the concentration of dioxane solution. 4) After autohydrolysis and lignin extraction of Populus alba-glandulosa, the extractable Klason lignin content by extraction increased with lengthening the auto hydrolysis time from 30 minutes to 60 minutes and with 2% 2-naphthol addition. The extractable lignin content was the highest after extraction by 90% or 75% dioxane solution. In case of Pinus koraiensis, the extractable lignin content increased with 2% 2-naphthol addition. Extractions by 100%, 90% and 50% dioxane solutions were more effective for the extraction of Klason lignin than by 75% dioxane solution. 5) After autohydrolysis and lignin extraction of Populus alba-glandulosa, the yield of reducing sugars increased with lengthening the autohydrolysis time from 30 minutes to 60 minutes but was not affected by 2% 2-naphthol addition and the concentration of dioxane. The yield of reducing sugars after enzymatic hydrolysis was slightly higher by extractions with 90%, 75% and 50% dioxane solutions than with 100% dioxane. In case of Pinus koraiensis, the yield of reducing sugars was not affected by 2% 2-naphthol addition but affected by the concentration of dioxane. The yield of reducing sugars was the highest in cellulosic substrates extracted by 100% dioxane solution.