• Advances in concrete construction
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• 제10권5호
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• pp.417-429
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• 2020

Waste glass is a global solid waste with huge reserves. The discarded waste glass has caused a series of problems such as resource waste and environmental pollution, so it is urgent to recycle waste glass with high replacement level. Glass powder (GP), as a supplementary cementitious material (SCM), used in cement-based materials has already become one of the important ways to recycle waste glass mainly attributed to its pozzolanic reaction and filling effect, especially to the suppressed ASR expansion. This paper demonstrates an overview of the properties of GP and its effect on the fresh and mechanical properties of cement-based materials. The study found that the influence of GP on the performance of cement-based materials mainly depends on its content, particle size, color and type, curing conditions, and other SCMs. Finally, based on the problems involved in the investigation of concrete containing GP, some corresponding suggestions and efforts are given to further guide the utilization of GP in cement-based materials.

• Advances in concrete construction
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• 제8권1호
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• pp.21-31
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• 2019

The rich recipe of ultra high performance concrete (UHPC) offers the higher mechanical, durability and dense microstructure property. The variable like cement/sand ratio, amount of supplementary cementitious material, water/binder ratio, amount of fiber etc. alters the UHPC hardened properties to any extent. Therefore, to understand the effects of these variables on the performance of UHPC, inevitably a stage-wise development is required. In the present experimental study, the effect of sand/cement ratio, the addition of finer material (fly ash and quartz powder) and, hybrid fiber on the fresh, compressive and microstructural property of UHPC is evaluated. The experiment is conducted in three phases; the first phase evaluates the flow value and strength attainment of ingredients, the second phase evaluates the efficiency of finer materials (fly ash and quartz powder) to develop the UHPC and the third phase evaluate the effect of hybrid fiber on the flow value and strength of ultra high performance hybrid fiber reinforced concrete (UHP-HFRC). It has been seen that the addition of fly ash improves the flow value and compressive strength of UHPC as compared to quartz powder. Further, the usage of hybrid fiber in fly ash contained matrix decreases the flow value and improves the strength of the UHP-HFRC matrix. The dense interface between matrix and fiber and, a higher amount of calcium silicate hydrate (CSH) in fly ash contained UHP-HFRC is revealed by SEM and XRD respectively. The dense interface (bond between the fiber and the UHPC matrix) and the higher CSH formation are the reason for the improvement in the compressive strength of fly ash based UHP-HFRC. The differential thermal analysis (DTA/TGA) shows the similar type of mass loss pattern, however, the amount of mass loss differs in fly ash and quartz powder contained UHP-HFRC.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제10권1호
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• pp.33-47
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• 2006

Finding good ways to support the further development of mathematically gifted students is a challenge for all mathematics educators. Simply moving able students on more rapidly to the next level of traditional mathematical instruction seems to be a limited approach, while providing supplementary enrichment material or specialized mathematical software requires us to ensure that doing so is truly worthwhile for the students. This paper presents an approach that the author has used with students of diverse capabilities in both technologically advanced and developing nations investigating mathematical ideas using a spreadsheet.

• 한국광학회지
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• 제1권1호
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• pp.98-106
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• 1990

Lasers are used increasingly for specialized engineering applications such as drilling, profile cutting, welding and surface heat-treatment(hardening, alloying, annealing0 of metals and non-metals. The most important characteristics of lasers used for these materials-processing applications are reviewed, with special emphasis on the importance of the controlled heating process. In addition to these processes, some optical devices and supplementary equipment used in laser processing are introduced. Finally, some examples shows the wide variety of laser capability for substitution of traditional materials processing.

• Advances in concrete construction
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• 제9권3호
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• pp.279-287
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• 2020

This paper focuses on the engineering properties of Bentonite-Cement-Sodium silicate (BCS) grout, which was prepared by partially replacing the ordinary Portland cement in Cement-Sodium silicate grout with lithium bentonite (Li-bent) and sodium bentonite (Na-bent), respectively. The effect of different Water-to-Solid ratio (W/S) and various replacement percentages of bentonite on the apparent viscosity, bleeding, setting time, and early compressive strength of BCS grout were investigated. The XRD method was used to detect its hydration products. The results showed that both bentonites played a positive role in the stability of BCS grout, increased its apparent viscosity. Na-bent prolonged the setting time of BCS, while 5% of Li-bent shortened the setting time of BCS. The XRD analysis indicated that the hydration products between the mixture containing Na-bent and Li-bent did not differ much. Using bentonite as supplementary cementitious material (SCM) to replace partial cement is a promising way to cut down on carbon dioxide emissions and to produce low-cost, eco-friendly, non-toxic, and water-resistant grout. In addition, Li-bent was superior to Na-bent in improving the strength and the thickening of BCS grouts.

• 대한후두음성언어의학회지
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• 제10권2호
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• pp.97-101
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• 1999

The nasalance score measured by Nasometer is a supplementary data for the perceptually rated nasality by a trained speech pathologist. Because the nasalance score varies with speech material, a valid and reliable material should be developed for evaluating it. The objectives of the present study were (1) to examine whether phonetic contexts affect the nasalace score and (2) to examine the reliability of both meaningless one-syllable words and meaningful sentences. This study analyzed nasalance score in 20 different phonetic contexts from 24 normal adults. The results showed (1) nasalance score increased as the percentage of nasal consonants and vowel /i/ increased, (2) the manner and the place of articulation in oral consonants did not influence the nasalance score, and (3) in nasalance score, correlation between sentences was found to be high, but correlation between syllables was not. These results may indicate that, when preparing the speech material for measuring the nasalance score, it is important to consider not only the percentage of nasal consonants but also that of vowel /i/ in the speech material. In addition, the sentence is more reliable material than meaningless one-syllable words.

• 한국지역지리학회지
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• 제23권1호
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• pp.213-226
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• 2017

지리교과서는 부도(atlas)와 함께 공인된 지리 교육 교재로서 교육현장에서 널리 사용되는 책자 형태의 인쇄자료이다. 특히 부도는 지리교과서의 내용을 이해하고 학습하는데 보조적인 역할을 하는 교재로 이해할 수 있다. 본 연구에서는 현행 교과서 검정체제하에서 발행되어 교육현장에서 사용하는 교과서와 부도의 상호보완성이 어떻게 구현되며 이와 관련된 문제점은 무엇인지 검토하였다. 지리 교과서와 사회과 부도는 교육과정에 근거하여 편찬되는데 저자들과 제작자들의 교육과정 해석, 교육적 신념과 관심 등에 따라 검정본을 완성하여 제출한다. 검정과정을 통과한 교재는 비로소 교육현장에 배포되어 지리 학습에 활용된다. 교과서와 부도 두 교재의 내용구성은 하나의 교육과정 진술에 대해 다양한 자료가 제시되고 두 교재에 제시된 자료는 상호보완적으로 구성되어 있지만, 때로는 각각의 교과서에 유사한 자료가 제시되거나 교과서에 제시된 자료와 사회과 부도 내용상 구성이 중복되거나 독립적일 수 있다. 현재와 같은 교과서 검정 제도하에서 두 교재가 효율적으로 지리 학습에 활용될 수 있는 방안이 모색되어야 할 것이다.

• Journal of Ginseng Research
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• 제29권4호
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• pp.206-214
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• 2005

The health function food law has been carried into effect from January 31, 2004 just after the proposal of 'a draft of a proposed law concerning the health function foods for the promotion of a nation health' on November 29, 2000 in Korea. After enforcement of health functional food law, there have been difficult market penetration with overall stagnancy of business activities and the current of health functional food within the country divided two groups. In standardized health functional foods the present condition, nutrition supplementary products (938 items) and red ginseng products (351 items) are prevalent and total 32 products are registered containing lactobacilli (297 items), glucosamine (295 items), ginseng (182 items), yeast(136 items) so on. In 2005, five products (products containing green tea extract, soybean protein, plant sterol, fructooligo sugar and Monascus sp. products are newly notified and raw material or component of total 21 products containing xylitol, teanin extract, sardine peptide are recognized as individual authorized health functional foods. Efficacies of ginseng are studied in many-sided researches but benefits of the ginseng in the health functional food law limited to 3 items (staminaresume, immune enhancement, nourishment robustness). To enlarge functionalities of ginseng it needs raw material and ingredient approval through data application to Korea Food and Drug Administration and this procedure acts as barrier of the functional food development in the ginseng industry. It is necessary to develop the authorized health functional foods for leading health functional food market in the future.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.121-126
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• 1998

Increased costs for cement have favoured the use of supplementary cementing materials in concrete. The use of fly ash in concrete has increased in the past few years. Concrete have been selected for use as a construction material in aggressive environment. The use of fly ash as concrete material has a role, and an understanding of its effect on concrete durability is essential to its correct and economical application. In this study, durability tests including permeability, freezing thawing resistance for Korean fly ash concrete are conducted. The durability characteristics of fly ash concrete are discussed.

• 산업공학
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• 제15권4호
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• pp.364-373
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• 2002

This paper developed an operating software for the manufacturing cell of a model plant. The model plant, which was manufactured by Fishertechnik, consists of an assembly cell, a machining cell, and supplementary material handling equipments. Each I/O module of the model plant communicates with the INTERBUS controller devices via High-level Language Interface(HLI). The machining center has two machining cells, which consists of 4 machines respectively, two 3-axis portal transporters, and a rail guided vehicle(RGV). The Petri-Net was used to investigate the dynamics of each machining cell, e.g., the relation of material handling equipments and machines. The operating software was analyzed and designed by Object Oriented Technique. The software was implemented using Delphi 3.0 under Windows 95/NT operating system.