• 자원리싸이클링
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• 제28권5호
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• pp.3-18
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• 2019

청정에너지에 대한 수요가 증가함에 따라 리튬이온배터리의 소비가 꾸준히 늘어날 것으로 예상된다. 따라서 전세계적으로 리튬의 안정적 공급이 중요한 문제가 되고 있다. 저품위 광석, 점토, 해수 그리고 폐리튬이온배터리 등과 같은 다양한 자원으로부터 리튬의 회수를 위한 공정과 기술들이 개발되어져 왔지만, 대부분의 리튬은 간수와 스포듀민 광석으로부터 상업적으로 생산되고 있다. 특히, 휴대폰과 전기자동차(EVs)를 포함한 여러 분야에서 발생하고 있는 사용 후 리튬이온배터리에 대한 재활용 기술들의 상용화는 많은 잠재력을 가지고 있다. 본 고찰은 폐리튬이온배터리에 대하여 새롭게 개발된 리튬 회수 공정과 더불어 광물과 간수를 이용하기 위한 상용공정 및 최신 기술들을 소개한다. 아울러 미래의 리튬 공급이 기술적인 관점에서 논의된다. 저품위 광석으로부터 리튬 회수를 위하여 개발되고 있는 최신공정들은 주로 건식+습식 제련에 기반을 둔 접근방법에 초점을 두고 있으며, 단지 몇몇 방법들만이 안정화 되었다. 리튬이온배터리의 소비(현재 생산되는 리튬의 56%)에 비교하여 리튬의 낮은 재활용율(1% 미만) 때문에 2차 자원의 처리는 굉장한 기회로서 앞을 내다보는 것일 수 있다. 또한 탄소경제, 환경과 에너지에 대한 우려를 생각해 볼 때, 습식제련공정이 이러한 이슈를 해결할 수 있을 것이다.

• 자원리싸이클링
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• 제33권1호
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• pp.58-68
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• 2024

핵심광물인 니켈, 코발트, 리튬은 NCM계 리튬이온배터리(이하 LIB)의 양극소재로 알려져 있다. 탄소중립 기조에 따라 전기자동차의 보급량 증가로 핵심광물 수요도 증가할 것으로 예상된다. 하지만, LIB용 핵심광물 Li, Co, Ni의 수요대비 공급 부족으로 인해, 폐리튬이온배터리(EOL LIB)의 리싸이클링 수요가 증가할 것으로 예상된다. EOL LIB(폐 LIB) 재활용은 유해화학물질 무기산 침출제인 염산(HCl), 질산(HNO₃), 황산(H₂SO₄)을 침출공정에 적용하여 재활용한다. 본 연구에서는 친환경 대체침출제 메탄술폰산(이하 MSA)의 적용 가능성을 검토하였다. 또한, 침출제 농도, 환원제 농도, 침출시간, 광액농도(P/D), 온도 등의 침출인자가 NCM Black mass 침출에 미치는 영향을 연구하였다. 침출실험 결과, 침출제와 환원제 농도, 침출시간, 침출온도가 증가함에 따라 목적금속 Ni, Li, Co, Mn의 침출률이 향상됨을 확인하였고, 금속의 최대 침출률은 80℃에서 99% 이상으로 나타났다. 또한, MSA는 NCM Black mass 대상 침출에 적용하여 Ni, Li, Co, Mn을 회수할 수 있음을 확인하였다.

• 광물과 암석
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• 제36권3호
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• pp.185-197
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• 2023

구봉 금-은 광상은 선캠브리아기의 변성퇴적암류내에 발달된 열극대를 충진한 8개조의 석영맥으로 구성된 조산형과 intrusion-related형이 혼합된 광상으로 과거 한국에서 가장 큰 금-은 광상들 중의 하나였다. 대한광업진흥공사는 이 광상의 남부에서 시추(90-12)를 통한 심도 -728 ML에서 27.9 g/t Au 품위를 갖는 0.9 m 폭을 갖는 석영맥(6호맥)을 착맥하였으며 2004년 재차 6호맥의 재개발 가능성 검토를 위해 시추(04-1)를 수행하였다. 2004년 시추 현장에서 모암, 모암변질 및 석영맥 시료들(04-1)을 채취하여 함 티타늄 광물들(티탄철석, 금홍석)의 산상과 화학조성을 연구하였다. 심도 -275 ML의 광화대에서 관찰되는 금홍석은 모암변질대에서 칼리장석, 흑운모, 석영, 방해석, 녹니석 및 황철석과 함께 산출된다. 심도 -779 ML의 광맥(6호맥)에서 관찰되는 티탄철석과 금홍석은 모암변질대와 석영맥에서 백색운모, 녹니석, 인회석, 저어콘, 석영, 방해석, 자류철석 및 황철석과 함께 산출된다. 이들 광물조합을 토대로, 금홍석은 열수 용액에 의한 모암내 Ti을 풍부하게 함유한 흑운모의 열수변질작용(녹니석화작용) 시 형성된 것으로 생각된다. 티탄철석은 최대 0.09 wt.% (HfO₂), 0.39 wt.% (V₂O₃), 0.54 wt.% (BaO) 함량이 함유되어 있다. 심도 -275 ML과 -779 ML에서 산출되는 금홍석의 화학조성을 비교하면, 심도 -779 ML의 광맥(6호맥)의 금홍석에서 WO₃, FeO 및 BaO 원소들의 함량이 높다. 이들 미량원소들은 심도 -275 ML의 금홍석 Ba²⁺ + Al³⁺ + Hf⁴⁺ + (Nb⁵+, Ta⁵⁺) ↔ 3Ti⁴⁺ + Fe²⁺, 2V⁴⁺ + (W⁵⁺, Ta⁵⁺, Nb⁵⁺) ↔ 2Ti⁴⁺ + Al³⁺ + (Fe²⁺, Ba²⁺), Al³⁺ + V⁴⁺ + (Nb⁵⁺, Ta⁵⁺) ↔ 2Ti⁴⁺ + 2Fe²⁺, 심도 -779 ML의 금홍석 2(Fe²⁺, Ba²⁺) + Al³⁺ + (W⁵⁺, Nb⁵⁺, Ta⁵⁺) ↔ 2Ti⁴⁺ + (V⁴⁺, Hf⁴⁺), Fe²⁺ + Al³⁺ + Hf⁴⁺ + (W⁵⁺, Nb⁵⁺, Ta⁵⁺) ↔ 2Ti⁴⁺ + V⁴⁺ + Ba²⁺로써 치환관계가 있었다. 이들 자료와 기 연구된 조산형 금 광상에서 산출되는 함 티타늄 광물들의 화학조성과 비교 검토 본 결과, 구봉 광상의 금홍석들은 다른 조산형 금 광상(운산 광상, Kori Kollo 광상, Big Bell 광상, Meguma 함 금 석영맥)들에서 산출되는 금홍석들보다 상대적으로 산화 환경에서 형성되었음을 알 수 있다.

• 한국양식학회:학술대회논문집
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• 한국양식학회 2003년도 추계학술발표대회 논문요약집
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• pp.17-18
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• 2003

Although flounder is one of the most important marine fish for aquaculture in Korea, feeding the flounder in commercial farms depends mainly on moist pellet in which over 70% frozen fishes (e.g. frozen horse mackerel) are incorporated in its formulation. Therefore, for further expansion of flounder farming, it is essential to employ practical formulated feeds that can support reasonable growth. Development of nutritionally balanced and cost-effective feeds is dependant on the information about nutritional requirement and feed utilization of the species. Nutrient and energy source in feed are needed for the growth and maintenance of fish. Protein is probably the most important nutrient affecting fish growth and feed cost. Therefore, it is essential to determine the optimum dietary protein level for the growth of fish, both its high proportion in the feed and because it is the main factor in determining feed cost. Dietary energy level is also critical because protein source in the feed is utilized as an energy source when the feed deficient in energy is fed to fish, whereas when the feed excess in energy is fed to fish, feed consumption decreased and resulted in growth reduction due to lack of other necessary nutrients for normal growth. Improper dietary protein, energy levels and/or their ratio will lead to an increase of fish production cost and deterioration of water quality resulting from wasted feed; thus, they are important in formulating commercial feed. Dietary lipids play important roles in providing energy and essential fatty acid for normal growth and survival of fish. Although carbohydrates are not essential nutrients for carnivorous fish, these compounds play important roles as a low-cost energy source for protein sparing and also as a feed binder. Nutrition researches for flounder have identified its requirements of protein, lipid and essential fatty acid, vitamin, and minerals for normal growth. Other studies have also been carried out to investigate the utilization of the protein, lipid and carbohydrate sources. Based on these nutritional information obtained, practical feed formulations have been studied for improve aquaculture production of flounder. The results of the researches on utilization of dietary protein, lipid and carbohydrate by flounder are discussed in this review.

• 한국연초학회지
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• 제20권1호
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• pp.5-12
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• 1998

Pot experiment was conducted to investigate the effects of fly ash on growth responses and on accumulation of the heavy metals in soil. Two kinds of fly ash, anthracite and bituminous coal, were treated with different levels of 0, 0.4, 0.8, and 1.2 kg/pot(20L). Tobacco growth was better by application of fly ash than that by the control. However, the early stage of growth by application of bituminous coal, 1.2 kg/pot, was decreased due to the boron toxicity occurred by fly ash. Generally, tobacco yield was significantly increased with applying fly ash, showing the highest yield at 1.2 kg/pot for anthracite and at 0.8 kg/pot for bituminous coal. The content of total nitrogen in leaves was higher with fly ash than that of the control, while the content of calcium in leaves was low, Contents of heavy metal and the other minerals were not significantly different between the control and the treatment of fly ash. Soil pH after experiment was linearly increased with application level of fly ash, indicating that the application of bituminous coal was more effective than that of anthracite. Contents of available phosphate, exchangeable $Ca^{2+}$+ and $Mg^{2+}$ in soil were increased by application of fly ash, especially with bituminous coal. Contents of Cu, Cr, and Ni were increased with application level of bituminous coati even if the contents were still lower than critical levels for farming land. The other heavy metals were similar between the control and the application of fly ash.

• Structural Engineering and Mechanics
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• 제64권4호
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• pp.391-402
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• 2017

In this paper, a new nonlocal trigonometric shear deformation theory is proposed for thermal buckling response of nanosize functionally graded (FG) nano-plates resting on two-parameter elastic foundation under various types of thermal environments. This theory uses for the first time, undetermined integral variables and it contains only four unknowns, that is even less than the first shear deformation theory (FSDT). It is considered that the FG nano-plate is exposed to uniform, linear and sinusoidal temperature rises. Mori-Tanaka model is utilized to define the gradually variation of material properties along the plate thickness. Nonlocal elasticity theory of Eringen is employed to capture the size influences. Through the stationary potential energy the governing equations are derived for a refined nonlocal four-variable shear deformation plate theory and then solved analytically. A variety of examples is proposed to demonstrate the importance of elastic foundation parameters, various temperature fields, nonlocality, material composition, aspect and side-to-thickness ratios on critical stability temperatures of FG nano-plate.

• Asian-Australasian Journal of Animal Sciences
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• 제3권1호
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• pp.7-13
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• 1990

Nutritional status of cattle in Java in Indonesia was investigated by evaluating P, Ca, Mg, K and Na concentrations in forage and plasma inorganic phosphorus (Pi), Ca and Mg, hematocrit and hemoglobin concentrations of cattle during both rainy and dry seasons in 1988. Investigations were conducted at Jonggol (West Java), Malang (East Java) and Majokerto (East Java). Low P content in forage averaging 0.11% on a dry matter basis, high Ca:P ratio in forage in the rainy season (7.7:1) and low plasma Pi concentrations averaging 4.71 mg/dl were observed in Jonggol. In all three places, Ca content in forages was higher than the requirement according to the NRC standard and plasma Ca concentrations were above the critical level. During the rainy season forty percent of cattle in Malang and Mahokerto showed plasma Mg concentrations below 2mg/dl in spite of normal Mg and K content in forage. Forage samples from each place showed a wide variety in Na content, and Na content of two thirds of forage samples was lower than the requirement according to the NRC standard. Hematocrit and hemoglobin concentrations in Malang and Majokerto showed higher values than the normal range.

• 한국식생활문화학회지
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• 제29권6호
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• pp.659-667
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• 2014

Fruits are good sources of vitamins, minerals, fiber, and phytochemicals, which are known to reduce serum lipids, oxidative damage, and blood pressure as well as improve blood glucose control. The purpose of this study was to estimate nutrient quality indices of fruits by carrying out a critical analysis of pre-existing methods according to their nutritional compositions. Four methods were used to assess the nutrient indices of 26 fruits, which are frequently consumed by Koreans based on the fourth Korean National Health and Nutrition Examination Survey (2009). Naturally nutrient rich score (NNR), nutrient rich food (NRF), nutrient adequacy score (NAS), and nutrient density score (NDS) were used to calculate nutrient quality indices. The Korean Nutrition Society Food Composition database of fruits based on 100 g edible portions was used. The algorithm of each method included the mean percentage of daily values (Dietary Reference Intakes for Koreans, 2010) for particular nutrients based on consumption of 1,900 kcal/day. The relative score indicated that strawberries, kumquat, and lemon had high nutrient quality indices. In addition, mango, lemon, persimmon, strawberry, apricot, and tangerine fruits are rich in antioxidant nutrients such as ${\beta}$-carotene, vitamin C, vitamin E, and selenium. However, scores of nutrient quality indices did not imply that higher scores of particular fruits are superior. We suggest moderate seasonable consumption a variety of fruits. Our results can be used as a reference for consumers when they choose fruits.

• 펄프종이기술
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• 제32권5호
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• pp.72-79
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• 2000

On the other hand, the fiber orientation at the surface and middle layer of the sheet controls the bending stiffness of paperboard. Therefore, a reliable measurement of paper surface fiber orientation gives us a magnificent tool to investigate and predict paper curling and cockling tendency, and provides the necessary information to fine-tune the manufacturing process for optimum quality. Many papers, especially heavily calendered and coated grades, do resist liquid and gas penetration very much, being beyond the measurement range of the traditional instruments or resulting inconveniently long measuring time per sample. The increased surface hardness and use of filler minerals and mechanical pulp make a reliable, non-leaking sample contact to the measurement head a challenge of its own. Paper surface coating causes, as expected, a layer which has completely different permeability characteristics compared to the other layers of the sheet. The latest developments in sensor technologies have made it possible to reliably measure gas flow n well controlled conditions, allowing us to investigate the gas penetration of open structures, such as cigarette paper, tissue or sack paper, and in the low permeability range analyze even fully greaseproof papers, silicon papers, heavily coated papers and boards or even detect defects in barrier coatings! Even nitrogen or helium may be used as the gas, giving us completely new possibilities to rank the products or to find correlation to critical process or converting parameters. All the modern paper machines include many on-line measuring instruments which are used to give the necessary information for automatic process control systems. Hence, the reliability of this information obtained from different sensors is vital for good optimizing and process stability. If any of these on-line sensors do not operate perfectly as planned (having even small measurement error or malfunction), the process control will set the machine to operate away from the optimum, resulting loss of profit or eventual problems in quality or runnability. To assure optimum operation of the paper machines, a novel quality assurance policy for the on-line measurements has been developed, including control procedures utilizing traceable, accredited standards for the best reliability and performance.

• Computers and Concrete
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• 제25권4호
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• pp.311-325
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• 2020

In this research work, the hygrothermal and mechanical buckling responses of simply supported FG sandwich plate seated on Winkler-Pasternak elastic foundation are investigated using a novel shear deformation theory. The current model take into consideration the shear deformation effects and ensures the zero shear stresses on the free surfaces of the FG-sandwich plate without requiring the correction factors "Ks". The material properties of the faces sheets of the FG-sandwich plate are assumed varies as power law function "P-FGM" and the core is isotropic (purely ceramic). From the virtual work principle, the stability equations are deduced and resolved via Navier model. The hygrothermal effects are considered varies as a nonlinear, linear and uniform distribution across the thickness of the FG-sandwich plate. To check and confirm the accuracy of the current model, a several comparison has been made with other models found in the literature. The effects the temperature, moisture concentration, parameters of elastic foundation, side-to-thickness ratio, aspect ratio and the inhomogeneity parameter on the critical buckling of FG sandwich plates are also investigated.