• Journal of the Korean Wood Science and Technology
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• 제47권1호
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• pp.110-123
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• 2019

This work was conducted to examine the relationship between lignin content and the durability of larch (LAR) pellets. LAR sawdust was immersed in tap water (TW), sulfuric acid (AC) and sodium hydroxide (AK) solutions, and then the immersed sawdust was used for pellet fabrication. Klason lignin (KL) content of the immersed LAR, contents of soluble lignin (SL) and monomeric sugars liberated from the immersion of LAR, and durability of LAR pellets were measured. KL content decreased as the concentration of AC and AK solutions increased, but glucose content increased with increase in AC and AK concentration. Durability of wood pellets fabricated using non-immersed LAR sawdust was the highest, followed by those made using TW-, AK- and AC-immersed sawdust. LAR pellets became more durable as the concentration of KL and SL increased, but a significant positive correlation was found only between pellet durability and KL content. Through the fluorescent microscopic observation and SEM-EDX analysis, it was verified that lignin content of non-immersed LAR pellets was higher than that of AC- and AK-immersed LAR pellets. These results suggest that lignin might contribute to an increase in inter-particle bonding in wood pellets.

• IEIE Transactions on Smart Processing and Computing
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• 제4권4호
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• pp.231-236
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• 2015

In this paper, the technical analysis and characteristics of screen content coding (SCC) based on High efficiency video coding (HEVC) are presented. For SCC, which is increasingly used these days, HEVC SCC standardization has been proceeded. Technologies such as intra block copy (IBC), palette coding, and adaptive color transform are developed and adopted to the HEVC SCC standard. This paper examines IBC and palette coding that significantly impacts RD performance of SCC for screen content. The HEVC SCC reference model (SCM) 4.0 was used to comparatively analyze the coding performance of HEVC SCC based on the HEVC range extension (RExt) model for screen content.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8292-8296
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• 2015

본 연구에서는 동충하초 추출물을 이용한 건강지향적인 리큐르를 개발하고, 제조방법에 대한 기준을 마련하였다. 동충하초 리큐르는 Sample을 21가지의 처리구로 나누어 제조하였고, 각각의 Cordycepin의 함량, Cordycepin의 안정성, 알코올 함량(Methanol and Ethanol)을 분석하였다. 시료 내 Cordycepin 함량분석 결과 증류 후에 동충하초를 넣고 3개월 침출한 시료의 경우(DL-3) 최대 $58{\mu}g/mL$ 검출되었고 발효 시에는 동충하초를 넣는 것은 무의미하므로 증류 후 동충하초를 넣어야 할 것으로 생각된다. 시료의 알코올 함량 분석 결과 Methanol은 시료 모두에서 검출되지 않았다. Ethanol 함량은 증류 후에 동충하초를 3개월 침출한 군에서 31.4%와 막걸리에 동충하초를 8 g 첨가한 군에서 17.2%로 나타내었다. Cordycepin의 안정성을 분석한 결과 Cordycepin 함량이 보관도중에 조금씩 감소하는 결과를 보여 제품 생산 시 함량을 조금 높여서 생산하여야 할 것으로 생각된다.

• 한국치위생학회지
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• 제19권6호
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• pp.1077-1087
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• 2019

Objectives: The purpose of this study was to analyze the risk of dental caries and erosion associated with beverage consumption by measuring the sugar content and acidity of beverages for children, marketed in general food stores and cooperative living associations in Korea. Methods: Sixty types of children's beverages marketed in Korea were selected for the study. Calories, sodium, and carbohydrates in the nutrients per 100 ml, the sugar content, and pH of each beverage were measured. Frequency analysis, independent t-test, and one-way ANOVA were performed (p<0.05). Results: There was no significant difference in sugar content, calories, sodium, and carbohydrate content of regular and cooperative beverages, but the pH of cooperative beverages was significantly higher. Moreover, the mixed drinks had significantly lower sugar content, calories, and carbohydrates than fruit and juice, but the sodium content was significantly higher. Conclusions: When choosing beverages for children, caregivers should be able to easily access information about their impact on the child's oral health. Efforts should be made to maintain appropriate levels of sugar and acidity in beverages for children.

• Computers and Concrete
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• 제20권2호
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• pp.165-176
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• 2017

Textile Reinforced Cementitious Composite (TRCC) became the most common construction material lately and have excellent properties. TRCC can be employed in the manufacture of thin-walled facade elements, load-bearing integrated formwork, tunnel linings or in the strengthening of existing structures. These composite materials are a combination of matrix and textile materials. There isn't much research done about the usage of polymer modified matrices in textile reinforced cementitious composites. In this study, matrix materials named as fine grained concretes ($d_{max}{\leq}1.0mm$) were investigated. Air entraining effect of polymer modifiers were analyzed and air void content of fine grained concretes were identified with different methods. Aim of this research is to study the effect of polymer modification on the air content of fine grained concretes and the role of defoamer in controlling it. Polymer modifiers caused excessive air entrainment in all mixtures and defoamer material successfully lowered down the air content in all mixtures. Latex polymer modified mixtures had higher air content than redispersible powder modified ones. Air void analysis test was performed on selected mixtures. Air void parameters were compared with the values taken from air content meter. Close results were obtained with tests and air void analysis test found to be useful and applicable to fine grained concretes. Air void content in polymer modified matrix material used in TRCC found significant because of affecting mechanical and permeability parameters directly.

• 한국통신학회논문지
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• 제30권4C호
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• pp.262-268
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• 2005

웹기반의 디지털콘텐트 전송은 웹 객체를 단위로 이루어진다. 따라서 웹기반 콘덴트 전송의 성능을 향상시키기 위해서는 웹 객체의 참조특성 분석을 통한 반영이 필요하다. 본 연구에서는 웹 객체의 참조특성의 분석을 통해 웹 객체의 전송 효율을 향상시킨 디지털콘텐트 전송 시스템을 설계하고 성능을 평가하였다. 제안시스템은 웹 객체의 참조특성을 반영하여, 캐싱 효율을 높임으로서 전체 시스템의 처리지연시간을 개선하는 것을 목적으로 하고 있으며 실험 결과 제안시스템의 성능이 우수함을 알 수 있었다.

• 인터넷정보학회논문지
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• 제24권6호
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• pp.49-55
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• 2023

본 연구에서는 유튜브 먹방 콘텐츠의 인기를 예측하는 모형을 제안하고 사후 분석을 통하여 먹방 콘텐츠의 인기에 영향을 주는 요인들을 식별하였다. 이를 위해 API와 Pretty Scale을 활용하여 구독자수 상위 먹방 채널들로부터 22,223개 콘텐츠의 정보를 수집하고 Random Forest, XGBoost 및 LGBM 등의 머신러닝 알고리즘을 기반으로 조회수와 좋아요수 예측모델을 구축하였다. SHAP 분석 결과 조회수 예측 모형에서는 구독자수가 예측에 가장 큰 영향을 미치는 반면, 좋아요수 예측 모형에서는 크리에이터의 매력도가 중요변수로 도출되는 등 콘텐츠 조회와 좋아요 반응에 대한 선행요인이 다름을 확인할 수 있었다. 본 연구는 대량의 온라인 콘텐츠를 분석하여 실증 분석을 진행하였다는 점에서 학술적 의의가 있으며 먹방 크리에이터들에게 시청자들의 콘텐츠 소비 경향을 알려주고 상품성 높은 콘텐츠 제작의 가이드를 제공한다는 점에서 실무적인 의의를 지닌다.

• International Journal of Advanced Culture Technology
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• 제12권3호
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• pp.441-448
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• 2024

The purpose of the study was to examine the effects of pre-service early childhood teachers' pedagogical content knowledge in mathematics and constructivist educational belief on mathematics teaching efficacy. The subjects were 187 pre-service early childhood teachers who enrolled in universities majoring early childhood education. We used self-reporting survey questionnaires to measure the major variables and utilized the SPSS 28.0 Program to analyze the collected data. Cronbach's alphas were calculated and the descriptive statistical analysis were conducted. To investigate the research questions, Pearson's correlation analysis and multiple regression analysis were done. As results, the higher the levels of pre-service early childhood teachers' pedagogical content knowledge in mathematics and constructivist educational beliefs, the higher their mathematics teaching efficacy. In addition, both pedagogical content knowledge in mathematics and constructivist educational belief were validated as the predictors of increased mathematics teaching efficacy of pre-service early childhood teachers.

• 자원환경지질
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• 제7권3호
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• pp.87-100
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• 1974

This paper deals with grain size analysis, heavy mineral analysis and trace element analysis of the recent sediments of Han River basin between Cheongpyong, Gyeonggi province and Seoul. For each location the samples are taken at river shoreline, river berm and river dune. The size analysis discloses that the mean values range from $-1.37{\phi}$ to $-1.60{\phi}$, sorting values range from 0.25 to 1.84, skewness values range from -0.44 to 0.51 and kurtosis values range from -0.1 to 1.75. Based on the textural parameters, the dune sand can be distinguished from the shoreline-berm sand. The content of heavy minerals of each sample ranges from 0.04 to 4.7%. The principal heavy minerals are ilmenite, magnetite, leucoxene, garnet, amphibole, pyroxene, kyanite, zircon, monazite, tourmaline, epidote, limonite, and minor minerals are apatite, sillimanite, andalusite and olivine. In general, dune sand samples contain more heavy minerals than the samples of shoreline or berm sand. This suggests that the heavy mineral concentration is affected by wind action more than by any other causes. The content of ilmenite and leucoxene decreases, whereas the content of zircon and epidote increases as it approaches the downstream region. The differences result from the variance of geological occurrences. The emission spectrochemical analysis and colorimetry analysis revealed that the content of Ni and V in the heavy minerals of the study area are higher than those of other stream sediments in Korea. On the other hand the content of Cu, Ph, Zn, Mo, W, P, Mn, Cr, Ag and Sn are lower in the study area. It has been observed also that the contents of all the elements except for Bi are higher in this area than the samples of marine sediments of Yellow Sea.

• Corrosion Science and Technology
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• 제22권1호
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• pp.64-72
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• 2023

Ni-Ti shape memory alloy for dental nerve treatment devices was prepared by adding Mo to Ni-Ti alloy to improve flexibility and fatigue fracture characteristics and simultaneously increase corrosion resistance. Surface properties of the alloy were evaluated. Microstructure analysis of the Ni-Ti-xMo alloy revealed that the amount of needle-like structure increased with increasing Mo content. The shape of the precipitate showed a pattern in which a long needle-like structure gradually disappeared and changed into a small spherical shape. As a result of XRD analysis of the Ni-Ti-xMo alloy, R-phase structure appeared as Mo was added. R-phase and B2 structure were mainly observed. As a result of DSC analysis, phase transformation of the Ti-Ni-Mo alloy showed a two-step phase change of B2-R-B19' transformation with two exothermic peaks and one endothermic peak. As Mo content increased, R-phase formation temperature gradually decreased. As a result of measuring surface hardness of the Ti-Ni-Mo alloy, change in hardness value due to the phase change tended to decrease with increasing Mo content. As a result of the corrosion test, the corrosion potential and pitting potential increased while the current density tended to decrease with increasing Mo content.