• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.11
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• pp.722-727
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• 2017

Transparent ZnS ceramics were synthesized by hydrothermal synthesis ($180^{\circ}C$ for 70 h), and were sintered by a hot press process at $950^{\circ}C$. To confirm the optical properties of the ZnS ceramics after sintering for various sintering holding times, we performed X-ray diffraction analysis, scanning electron microscopy, and Fourier-transform-infrared spectroscopy. The ZnS nanopowders was found to be single-phase (cubic) without any hexagonal phase. However, the hexagonal phase is formed and increases in content with increasing sintering holding time. The density of the ZnS ceramics was above 99.7%, except for the unsintered one. The ZnS ceramics showed high transmittance (~70%) when sintered for more than 2 h.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.883-892
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• 2014

Free-to-play business model, which first commercialized in Korea, now becomes crucial sales drivers in the game industry, but the theoretical background is not well known that most of free-to-play content business models are developed based on the guts and trial-and-errors. In this study, we verified that the price discrimination theory in economics is the backbone of the free-to-play business model, and we also derived the three boundary conditions that should be satisfied in the business model design. We reviewed the three boundary conditions of free-to-play business model using case studies of previous games, and showed how the boundary conditions should work in the actual business. Through case studies, we tried to suggest the theoretical basis of free-to-play business model design, and sales enhancing techniques in free-to-play business.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.73-82
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• 2014

PURPOSES : The purpose of this study is to determine the optimum addition rate of SBR latex through the evaluation of durability and strength of SBR latex applied soil pavement. Formerly used materials such as fly ash and cement in soil pavement had resulted in decreased durability due to micro crack by heat of hydration and shrinkage crack in winter. However, that agglutinated polymers help adhesion to aggregate increased comes up with preventing the crack opening when the number of capillary tubes of SBR latex get decreased in the hydration process of cement. Therefore, in this study, it is suggested that the evaluation of the field applicability of soil pavement be conducted through the performance lab test in terms of strength increment, adhesion improvement, and crack resistance based on SBR latex addition rate. METHODS : In order to evaluate the field applicability of soil pavement, SBR latex was added 0 to 3% by 1% increment, with fixed cement contents of 3% and 5%. The resistance of shear failure and crack of soil pavement were evaluated by performing the uniaxial compressive strength test and indirect tensile strength test at -20 and $20^{\circ}C$, respectively. RESULTSCONCLUSIONS : It was found out that from both tests, resistance of shear failure and crack were improved with increment of curing time, and especially more than 2% of SBR latex addition rate and 5% cement content gave better results.

• Journal of Dairy Science and Biotechnology
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• v.37 no.4
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• pp.213-222
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• 2019

Milk and dairy products are the high value foods for the elderly population. In particular, fermented milk is the best source of calcium for people in the specific age group of over 79 years. It provides a good source of protein. Regular exercise and active lifestyle are recommended to slow down the muscle loss. However, exercising without proper nutrient intake is simply not sufficient at this age. Milk and dairy products provide the iron and protein content required for effective exercise-assisted growth. Milk nutrients have the advantage of being produced in various food forms, such as liquid, semi-solid, and powder types. Fat-soluble vitamins such as retinol and vitamin K can be encapsulated using various technologies for milk and dairy products. Using the encapsulation method, spray drying and fluidized-bed coating have been used for adding the micro-nutrients to the food. Microencapsulation technology is being applied in case of the fermented dairy products too. In particular, various wall materials are being developed to enhance the viability of probiotics. In the near future, advanced high-efficiency technologies that can effectively nourish the dairy products with nutrients will be developed to produce targeted high-nutrition value food for the elderly.

• Journal of the Korea Furniture Society
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• v.19 no.6
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• pp.411-419
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• 2008

Xylia xylocarpa is fast-growing trees that are currently planted on trial basis in Sabah, Malaysia. The wood quality of trees grown in Sabah may differ from those grown in other places due to the environmental factors. Five 9-year-old trees of each species were extracted from their respective plots at Luasong, Tawau. Wood specimens were prepared from three height levels; bottom, middle and top, at the inner and outer radial positions. The within-tree and between-tree variations of physical properties of these species were analyzed. The basic density, oven-dry density and green moisture content(MC) are 0.72g/$cm^3$, 0.78g/$cm^3$ and 49.8% respectively. The shrinkage from green to oven-dry conditions for the radial and tangential directions were 3.35% and 5.76%, respectively. The trends of within-tree variations for most properties were more consistent in radial rather than vertical direction. This suggests diameter growth to be a more important factor contributing to the variations compared to height. Samples from the outer part of the stem were found to have higher density, shrinkage and mechanical strengths. The between-trees variations of some wood properties were found to be significantly different, probably due to genetic and micro-environmental factors. Significant correlation was recorded among the physical properties of the species. The true potential of X. xylocarpa for end-uses would be enhanced by further research such as the study on properties of wood from different sites and other properties like durability, seasoning, processing and machining characteristics. The characteristics of X. xylocarpa are comparable to a number of local popular hardwood species, indicating its suitability for heavy construction uses.

• Journal of Environmental Impact Assessment
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• v.16 no.4
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• pp.241-250
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• 2007

A study was carried out on the level of heavy metals, total coliform and benzo(a)pyrene that may be introduced through by-product fertilizers or air pollution to turfgrass in natural turfgrass playground in elementary schools around the western coast and eastern mountain areas in Jeollabuk-do, Korea. The level of heavy metals found in turfgrass was in the order of Cu > Zn > Pb > Cd. The majority of heavy metals was found in the roots. It is presumed that the absorption of some air pollutants and by-product fertilizers or chemical fertilizers. The level of benzo(a)pyrene showed an average of 0.05ng/g with a range between 0.02 to 0.08ng/g in the leaves. In the meantime, none was detected in the stems, while the average for roots was 0.02ng/g with a range between 0.01 and 0.03ng/g. The level detected is that found background level, however, benzo(a)pyrene can be introduced partly from the unstable combustion of fossil fuel or through vehicle emissions. Total coliform distributed in grass showed an average of 12MPN/100ml with a range between 2 and 36MPN/100ml. The density of total coliform displayed no regional predominance. However, in some urban areas, the density was slightly higher. The feces of pets or by-product fertilizers may have contributed to the input of pathogenic micro-organism. Yet the level was found to be negligible.

• Journal of Biosystems Engineering
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• v.41 no.2
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• pp.138-144
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• 2016

Purpose: Phosphorus is an essential element for water quality control. Excessive amounts of phosphorus causes algal bloom in water, which leads to eutrophication and a decline in water quality. It is necessary to maintain the optimum amount of phosphorus present. During the last decades, various studies have been conducted to determine phosphorus content in water. In this study, we present a comprehensive overview of colorimetric, electrochemical, fluorescence, microfluidic, and remote sensing technologies for the measurement of phosphorus in water, along with their working principles and limitations. Results: The colorimetric techniques determine the concentration of phosphorus through the use of color-generating reagents. This is specific to a single chemical species and inexpensive to use. The electrochemical techniques operate by using a reaction of the analyte of interest to generate an electrical signal that is proportional to the sample analyte concentration. They show a good linear output, good repeatability, and a high detection capacity. The fluorescence technique is a kind of spectroscopic analysis method. The particles in the sample are excited by irradiation at a specific wavelength, emitting radiation of a different wavelength. It is possible to use this for quantitative and qualitative analysis of the target analyte. The microfluidic techniques incorporate several features to control chemical reactions in a micro device of low sample volume and reagent consumption. They are cheap and rapid methods for the detection of phosphorus in water. The remote sensing technique analyzes the sample for the target analyte using an optical technique, but without direct contact. It can cover a wider area than the other techniques mentioned in this review. Conclusion: It is concluded that the sensing technologies reviewed in this study are promising for rapid detection of phosphorus in water. The measurement range and sensitivity of the sensors have been greatly improved recently.

• Ocean and Polar Research
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• v.26 no.1
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• pp.23-32
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• 2004

As a baseline survey for long-term monitoring on environmental change around the Antarctic King Sejong Station, distribution pattern of Deschampsia antarctica Desv., a flowering plant newly colonized were investigated qualitatively and quantitatively in both austral summer 2002 and 2003. Dispersal of the seeds and vegetative leaves by skuas might lead to the colonization into this area from neighbors in Maxwell Bay. The pioneer populations were observed around ponds and a stream of the Sejong Point in January 2002, and the maximum dispersal area was four times expanded after a year. Most of the populations were formed on the stable and well-drained substrate, which consisted of moss carpet of Sanionia georgico-uncinata (65%) and pebbles (25%), while only a few young individuals were observed on the unstable and watertight silt-sandy area. Especially, S. georgico-uncinata was being effectively utilized as their primary substrate with the soft, coarse and water-contained leaves. Also the perennial mature plants of D. antarctica were mainly formed on the moss carpet rather than pebbles. A few individuals were grown on other mosses of Polytrichastrum alpinum, Bryum pseudotriquetrum, Pohlia cruda, and Conostomum magellanicum and on a liverwort of Cephaloziella varians. We expect that dispersal of D. antarctica and the following succession to grass field will be countinuously and dynamically proceeded in this area, with the characteristics of ecological niche against the initial moss populations, on the similar continuity of environmental conditions. The continuous observations are needed with establishment of database on environmental change of micro-habitats, e.g. the water content and nutrients of soil and the underground temperature and permafrost.

• The Journal of the Korea Contents Association
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• v.17 no.12
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• pp.378-385
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• 2017

The aim of this study was to analyze cohesion and word information among different types of questions in the English reading section of the College Scholastic Ability Tests (CSAT). The types of questions were divided into three categories: macro reading, micro reading, and indirect writing. Reading texts from 1994 to 2017 CSAT were analyzed by Coh-Metrix, an automated evaluation program of text and discourse. The findings of this study indicated that there were statistical differences among the three categories of questions for noun overlap, stem overlap, adversative and contrastive connective, additive connective, pronoun incidence, age of acquisition, concreteness for content word, imagability, and meaningfulness. The information of the findings bore pedagogic implications for developing textbooks, questions for CSAT, and reading strategies by students.

• Journal of Korean Library and Information Science Society
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• v.47 no.1
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• pp.1-20
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• 2016

Humanities is one of the largest buzzword in Korea. Humanities programs are being provided indiscriminately in public authorities, universities, life-long education institutions, cultural centers, the media, museums, libraries etc. Among them, the public library is the base camp for spreading and popularizing the humanities. Nevertheless, there is also a critical views for the humanities program of public library. The purpose of this study is to discuss the discourse of the humanities banquet in theoretical positions and practical aspects. The former discussed the humanities banquet in terms of academic axioms, global macro and micro discourse, social and economic wave, the spirit cultural evolution. The latter discussed the humanities banquet at the axiom and identity of the library and humanities, pitfalls and limitations in terms of reason, paradox and the dilemma on the linkage side, inconvenient truth at the destination aspect, weaknesses and challenges in the content aspect.