• Economic and Environmental Geology
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• v.37 no.1
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• pp.143-151
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• 2004

This study focused on examining the possibility of recycling mine solid waste as environmental materials, especially for porous media. Basic properties including mineralogical compositions, chemical compositions, and particle size distribution of the tailings from the Sangdong W mine were checked. The mineralogical and chemical compositions of the tailings samples were not much different in depth. According to Korean Standard Leaching Test for Wastes(KSLT), concentrations of heavy metals leached from the tailings were below the standard values. As a result of particle size analysis, the median diameter (d$_{50}$) of the tailings was in the range of 10 to 30 ${\mu}{\textrm}{m}$. The stable tailings slurry made up of 3 ${\mu}{\textrm}{m}$ in d$_{50}$ was prepared using Attrition Mill. The milling condition was 40 vol% in slurry concentration, 700 rpm in stirring speed, and 1 hour in milling time. PEI was added as dispersing agent. Concentrated slurry was extended to 3 times by foaming method. In the case of 3 times foamed slurry, the total and open porosity of ceramic supports sintered at 1,075$^{\circ}C$ for 90 minutes was about 80% and 72%, respectively. Pore size was in the range of 30∼350${\mu}{\textrm}{m}$. Therefore, the tailings could be recycled starting material for environmental materials such as macroporous ceramic support.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.1
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• pp.61-66
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• 1995

This experiment was conducted to evaluate the effect of the various stage of growth on dry matter yield and chmical composition of forage oat(Avena sativa. L.). Seeds were planted on March 13 1993 on the Livestock Experimental Farm Keiymung junior college at keongsan Keongsangbukdo. Oat plant were harvested at various stages of maturity while the oat was in the premature stages. 1. Whole plant dry matter increased with advancing maturity. It was 11.8, 12.3, 14.9, 25.6 and 28.8% at before flag leaf emerged, flag leaf emerged, heads emerged, milk and dough stage., respectively. Dry matter increased very little during from before flag leaf emerged to heads emerged, after which it increased rapidly until the plant was dough stage. 2. Leaf weight ratio decreased with advancing maturity from before flag leaf emerged to dough, varied fmm 58 to 1 1%. Grain(with lemma, palea) increased with advancing maturity from heads emerged to dough, varied from 7 to 43%. 3. The content of cmde protein decreased during the stages of growth until milk(P<.OS), and then changed very little with advancing maturity. 4. The content of NDF and ADF increased rapidly during the early growth period until heading(P<.05) and then decreased due to the increase in carbohydrate storage in the grain. 5. The dry matter yields per ha increased with advancing maturity, it was 2,420, 4,380, 7,190, 13,130 and 14,530kg at before flag leaf emerged, flag leaf emerged, heads emerged, milk and early dough, respectively. Significant difference has been obtained among stages of growth(P< .05). 6. According to the results obtained from this study, it is suggested that milk stage of maturity is higher in dry matter yields would be recomendable for spring oat for silage.

• Journal of the Korean Wood Science and Technology
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• v.38 no.4
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• pp.298-305
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• 2010

The effects of wood species, chemical components, filler loading level, filler particle size, and coupling agent on the water absorption property of the wood flour filled polypropylene (PP) composites were investigated in this study. After 500, 1,000, 1,500, 2,000, 2,500 and 3,000 hr water immersion, Quercus (Quercus accutisima Carr.) and Maackia (Maackia amuresis Rupr. et Maxim) showed significantly lower water absorption properties compared to Larix (Larix kaempferi Lamb.). As wood flour loading increases from 10 to 50 wt%, most wood species showed increased water absorption after a given immersion period. Particle size of wood flour proved to have very significant effects on water absorption of the composites. The effect of coupling agent was positive in terms of lowering water absorption of the composites. As the treatment level of coupling agent increases, the water absorption of the composites decreases. The lowest water absorption was obtained at the lower wood flour loading (Maackia), smaller particle size and by the addition of coupling agent. Thickness swelling of the composites shows close dependency on water absorption.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.83-83
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• 2017

생체재료의 표면은 이식과 동시에 생체계면의 역할을 하게 되어, 일련의 생물학적 반응이 시작되고 진행되는 중요한 장소가 된다. 초기에 생체계면에서 일어나는 단백질 흡착이나 염증반응을 비롯한 생물학적 반응들은 궁극적으로 임플란트의 성패를 좌우할 만큼 중요하다. 골융합을 개선하기 위한 다른 방법으로 생체불활성의 타이타늄 (Ti)과 골조직의 능동적인 반응을 이루기 위해 생체활성 표면을 부여함으로서 계면에서의 골형성 반응을 증진시키는 방법이 이용된다. 생체불활성의 Ti과 Ti합금은 골조직과 직접적인 결합을 이루지 못하므로, 골조직과의 반응을 향상하기 위해 여러 종류의 생체활성 재료를 코팅하는 방법이 연구되어 왔고, 이 중 생체의 변화와 가장 유사한 하이드록시아파타이트 코팅이 가장 대중적인 방법으로 사용되었으며 이는 초기 골형성을 촉진하는 것으로 알려졌다. 치과용 임플란트의 표면형상과 화학조성이 골 융합에 영향을 미치는 가장 중요한 인자이므로 최근의 연구동향은 이들 두 가지 표면특성을 결합함으로서 결과적으로 최적의 골세포반응을 유도하고, 골융합 후 골조직과의 micromechanical interlocking에 의해 임플란트의 안정성에 중요한 역할을 하는 마이크론 단위의 표면조도와 표면 구조를 유지하면서, 부가적으로 골 조직 반응을 능동적으로 개선할 수 있는 생체활성 성분을 부여하여 골 융합에 상승효과를 이루기 위한 표면처리법에 관해 많은 연구가 요구되어지고 있다. 따라서 골을 구하는 원소인 망간과 실리콘으로 치환된 하이드록시아파타이트를 플라즈마 전해 산화법으로 코팅하여 세포와 잘 결합할 수 있는 표면을 제공함으로써 골 융합과 치유기간을 단축시킬 수 있을 것으로 사료된다. 실험방법은 시편은 치과 임플란트 제작 합금인 Ti-6Al-4V ELI disk (grade 5, Timet Co., USA; diameter, 10 mm, thickness, 3 mm)이며, calcium acetate monohydrate, calcium glycerophosphate, manganese(II) acetate tetrahydrate, sodium metasilicate을 설계조건에 따라 혼합 제조된 전해질 용액을 이용하여 플라즈마 전해 산화법으로 표면 코팅을 실시하였다. 각 시편의 플라즈마 전해시 전압은 280V로 인가하였고, 전류밀도는 70mA로 정전류를 공급하여 해당 인가전압 도달 후 3분 동안 정전압 방식을 유지하였다. 코팅된 피막 표면을 주사전자현미경과 X-선 회절분석을 통하여 미세구조 및 결정상을 관찰하였다. 또한 코팅된 표면의 생체활성 평가는 정량적으로 평가하기 위해 동전위시험과 AC 임피던스를 통하여 시행하였다. 분극거동을 확인하기 위해 potentiostat (Model PARSTAT 2273, EG&G, USA)을 이용하여 구강 내 환경과 유사한 $36.5{\pm}1^{\circ}C$의 0.9 wt.% NaCl에서 실시하였다. 전기화학적 부식 거동은 potentiodynamic 방법으로 조사하였고 인가전위는 -1500 mV에서 2000 mV까지 분당 1.67 mV/min 의 주사속도로 인가하여 시험을 수행하였다. 임피던스 측정은 potentiostat (Model PARSTAT 2273, EG&G, USA)을 이용하였으며, 측정에 사용한 주파수 영역은 10mHz ~ 100kHz 까지의 범위로 하여 조사하였고 ZSimWin(Princeton applied Research, USA) 소프트웨어를 사용하여 용액의 저항, 분극 저항 값을 산출하였다. 망간의 함량이 증가할수록 불규칙한 기공을 보였으며, 실리콘은 $TiO_2$ 산화막 형성을 저해하는 경향을 확인할 수 있었다. 단독으로 표면을 처리한 경우보다 두 가지 원소를 이용해 복합 표면처리를 시행한 경우가 내식성이 좋아 임플란트과의 골 유착에 긍정적인 영향을 미칠 것으로 사료된다.

• Journal of the Korean Chemical Society
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• v.40 no.5
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• pp.341-346
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• 1996

Electrochemical determination of iodide was carried out by stripping voltammetry with a $(Cin)Cu(NO_3)_2$ modified-carbon paste electrode. Iodide was coordinated onto the electrode surface containing $(Cin)Cu(NO_3)_2$ via ion exchange. The oxidation peak potential of incorporated iodide was ＋0.72 V. The optimum analytical conditions for the determination of iodide were investigated using linear sweep voltammetry. Optimum conditions for the electrochemical determination of iodide were as follows: i) A predeposition solution was 0.1 M $KNO_3.$ ii) The deposition time was 10 min. iii) The composition of the electrode was 40% (w/w). The detection limit for iodide was $1.0{\times}10^{-6}M$ and the relative standard deviation was ${\pm}5.5%\;in\;2.0{\times}10^{-5}M$(four repetitions). The interference effect of other anions were also investigated. $Cl^-,\;Br^-,\;C_2O_4^{2-},\;and\;ClO_4^-$ ions do not interfere for the determination of iodide. When $SCN^-$ was added to the deposition solution, the oxidation peak current of iodide ion was decreased roughly 32%.

• Korean Journal of Agricultural Science
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• v.14 no.2
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• pp.309-317
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• 1987

The raw milk produced in Korea was heated at $70^{\circ}C$, $75^{\circ}C$, $80^{\circ}C$, $85^{\circ}C$, $90^{\circ}C$, $95^{\circ}C$ and $100^{\circ}C/15sec.$. The changes in chemical composition and microbiological aspects of the milk were summarized as following results: 1. In high temperature pasteurized milks as the heat treatment increased, pH value decreased but protein, fat, lactose and ash did not show significant changes in their contents while casein nitrogen and non-protein nitrogen increased but non-casein nitrogen and filterable nitrogen decreased in their contents. 2. Calcium content of raw milk decreased from 119.79mg/100g to 111.86mg/100g at $75^{\circ}C$ and to 106.24mg/100g at $100^{\circ}C$. Vitamin C decreased from $1.37mg/100m{\ell}$ of raw milk to $1.15mg/100m{\ell}$ at $75^{\circ}C$ and $0.94mg/100m{\ell}$ at $100^{\circ}C$. Artificial digestibility increased as the heat treatment got higher. 3. Viable bacteria counts decreased from $9.0{\times}10^3/m{\ell}$ at $75^{\circ}C$ to $3.4{\times}10^2/m{\ell}$ at $100^{\circ}C$. Coliforms were not found at $70^{\circ}C$ and thermoduric bacteria, thermophiles, psychrotrophic bacteria, mould and yeast decreased rapidly as the heat treatment increased. 4. The results of Keeping quality test for high temperature pasteurized milk showed that the' milks preserved at $25^{\circ}C$ and $37^{\circ}C$ were clotted just after 1 day but the milk preserved at $4^{\circ}C$ showed good shelf life which did not have any deterioration in titratable acidity, microorganisms and com positions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.6
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• pp.862-868
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• 2005

Korean mountain ginseng roots were freeze-dried at $-70^{\circ}C$ and extracted by different extracting solution conditions to investigate chemical compositions of extracts. The soluble solid content of the extract from $7.04\~13.45\%\;and\;50\%$ EtOH and MeOH extracts were higher than those of other extracts. $100\%\;water\;and\;90\%$ EtOH extracts gave the highest Brix with $19.98\%$\;and\;19.65\%$, respectively. pH of the extracts were ranged from $5.82\~6.60$. Browning color at 470 nm of the extract were high value in 50$\%$ EtOH extract. In case of Hunter's color value, L value of extract was higher in $100\%$ water extract (21.28) than EtOH extract $(17.18\~21.02)$, a and b values of extract were the highest in $100\%$ water (-0.12) and $90\%$ MeOH extract (1.34). The contents of free sugars in the EtOH extract were increased with the ethanol concentration. Sucrose contents of $90\%$ EtOH and MeOH extracts were 6,159 mg/100 g and 5,238 mg/100 g. Major organic acids of the extract were citric and malic acids. Major free amino acids of the extract were L-arginine, L-proline, $\gamma$ -amino-n-butyric acid, alanine and aspartic acid. The highest ginsenoside content was shown to be about $10.50\%\;in\;90\%$ MeOH extract. Major minerals of extract were P, K, Na, Mg and Ca.

• Clean Technology
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• v.30 no.1
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• pp.37-46
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• 2024

Environmental problems caused by plastic waste have been continuously growing around the world, and plastic waste is increasing even faster after COVID-19. In particular, PP and PE account for more than half of all plastic production, and the amount of waste from these two materials is at a serious level. As a result, researchers are searching for an alternative method to plastic recycling, and plastic pyrolysis is one such alternative. In this paper, a numerical study was conducted on the pyrolysis behavior of non-condensable gas to predict the chemical reaction behavior of the pyrolysis gas. Based on gas products estimated from preceding literature, the behavior of non-condensable gas was analyzed according to temperature and residence time. Numerical analysis showed that as the temperature and residence time increased, the production of H₂ and heavy hydrocarbons increased through the conversion of the non-condensable gas, and at the same time, the CH₄ and C₆H₆ species decreased by participating in the reaction. In addition, analysis of the production rate showed that the decomposition reaction of C₂H₄ was the dominant reaction for H₂ generation. Also, it was found that more H₂ was produced by PE with higher C₂H₄ contents. As a future work, an experiment is needed to confirm how to increase the conversion rate of H₂ and carbon in plastics through the various operating conditions derived from this study's numerical analysis results.

• Korean Journal of Agricultural Science
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• v.26 no.1
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• pp.58-64
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• 1999

The chemical composition and ruminal dry matter digestibilities of leaves, stems and roots of Aralia cordata Thunberg were determined and compared each other as a roughage sources for ruminants. The crude protein contents were higher for leaves(12.4%) than for leaves+stems (9.7%), stem(5.1%) and roots (3.8%) (P<0.05). The crude fat contents were higher for leaves (3.7%) than for roots (2.1%) and stems (1.3%) (P<0.05). The crude fiber contents were lower for roots (12.3%) than for leaves (15.0%), leaves+stems (27.7%) and stems (40.3%) (P<0.05), respectively. The contents of neutral detergent fiber were lower for leaves (30.2%) than for leaves+stems (42.0%), roots (50.8%) and stems (60.0%) (P<0.05), respectively. The contents of acid detergent fiber were lower for root(18.3%) than for leaves(21.4%). leaves+stems (37.5%) and stems (49.6%) (P<0.05), respectively. The calcium content of leaves(2.4%) were higher than those of stems and roots (0.97% and 0.69%), however the phosphorus contents were similar among leaves, stems and roots(0.25%, 0.19% and 0.35%). Ruminal dry matter digestibilities for 12, 24, 48 and 72hr of leaves(38.9%, 65.9%, 79.8% and 82.4%) and roots(38.9%, 59.8%, 77.6% and 78.5%) were higher than stems(31.1%, 44.1%, 49.5% and 52.6%). Furthermore the digestibilities of leaves were higher than those of alfalfa hay(37.4%, 48.8%, 67.8% and 71.8%) and although the digestibilities of stems which were the lowest among the parts were higher than those of acasia wood chip(12.6%, 18.2%, 21.6% and 24.3%).

• Journal of Korean Society of Forest Science
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• v.50 no.1
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• pp.1-4
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• 1980

The Chemical components of Abies koreana Wilson grown in Korea were analized. The results obtained were summarized as follows. 1. The ash content is ca 0.56% on the average, and of the range is 0.33 to 0.76%. 2. The cold water extractive content is ca 8.76% on the average and of the range is 5.55 to 12.5%. 3. The hot water extractive content is ca 10.16% on the average and of the range is 4.80 to 13.65%. 4. Basic extractive content is ca 14.60% on the average and of the range is 5.51 to 25.44%. 5. The alcohol benzol soluble fraction is ca 4. 23% and of the range is 2.94 to 5.44%. 6. The holocellulose content is ca 76.49% on the average and of the range is 73.68% to 79.10%. 7. The cellulose content is ca 56.30% on the average and of the range is 46.02% to 61. 33%. The cellulose contains 78.54% ${\alpha}$-cellulose, 7.66% ${\beta}$-cellulose and 14.04% ${\gamma}$-cellulose respectively. 8. The Klason lignin content is ca 25.03% on the average and of the range is 22.5 to 27.0%. In conclusion, ash content is comparable to the other needle leaf trees. It has 76.49% in holocellulose content which is comparable value to the Pinus densiflora's. It has lower value than the Pinus densiffora in pentosan and lignin content. Having not resin cannal in xylem and long tracheid, this wood could be usable industrial material.