• 한국분말재료학회지
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• 제13권3호
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• pp.187-191
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• 2006

Al-Cu alloy nano powders were produced by the electrical explosion of Cu-plated Al wires. The composition and phase of the alloy could be controlled by varying the thickness of Cu deposit on Al wire. When the Cu layer was thin, Al solid solution and $CuAl_2$ were the major phases. As the Cu layer becomes thicker, Al diminished while $Al_4Cu_9$ phase prevailed instead. The average particle size of Al-Cu nano powders became slightly smaller from 63 nm to 44 nm as Cu layer becomes thicker. The oxygen content of Al-Cu powder decreased linearly with Cu content. It is well demonstrated that the electrodeposition combined with wire explosion could be simple and economical means to prepare variety of alloy and intermetallic nano powders.

• 한국재료학회지
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• 제16권8호
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• pp.497-502
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• 2006

Recently, many attention have been focused on illite as a material for the well-being industry. Illite contains various kinds of iron bearing materials and they restrict their usage. In this study, Fe impurities in the illite produced in Yeongdong-gun, Chungcheongbuk-do were characterized and their removal experiments were performed. According to the characterization of illite raw ore, it contained 1.54 wt.%$Fe_2O_3$ due to the existence of iron oxide($Fe_2O_3$) and pyrite($FeS_2$). The raw ore was crushed into 3 mm or less using cone crusher and then ground by rod mill for the liberation of impurity mineral. For the removal of iron bearing minerals, an acid treatment, a flotation, a magnetic separation, and a flotation combined with magnetic separator were performed respectively. When the illite raw ore was treated with magnetic separation and various kinds of acid, 1.54wt.%. $Fe_2O_3$ content was reduced to 0.78 and 1.0 wt.%, respectively. On the other hand $Fe_2O_3$ content was reduced to be 0.52 wt.% after flotation. These results indicate that iron bearing minerals cannot be reduced below 0.3wt.%$Fe_2O_3$. However, combination of magnetic separation and flotation enable us to get 0.24wt.% of illite concentrate. It is concluded that, for the refinement of illite from Yeongdong-gun, the flotation combined with magnetic separation is good for high purity illite.

• 자원환경지질
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• 제28권5호
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• pp.519-525
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• 1995

Recently, there have been several cases of serious accidents on concrete structure resulting from rapid deterioration of concrete strength. On the view point of long term stability of concrete, deterioration of concrete strength is mostly due to chemical reaction between alkali and reactive aggregates (alkali-aggreagte reaction; AAR) in concrete rather than a problem of execution. For long-term stability of concrete, concrete aggregates must be carefully selected. Some of rocks used for concrete aggregates contain deleterious minerals reactive to alkali components in concrete. Most of AAR result from chemical reaction between alkali components and reactive silica minerals in aggregates (so called alkali-silica reaction; ASR). The silica minerals are as follows; quartz with seriously distorted lattice structure, volcanic glass, chalcedony, opal, cristobalite, tridymite, etc. ASR may cause expansion and cracks, further collapse in concrete structure, in a few years. In case of crushed aggregates, only a part of rock mass without reactive minerals must be produced in aggregates mine after thorough examination of the distribution of rocks with reactive minerals. In case of natural aggregates, the total content of reactive minerals must be calculated, if, the content is more than 20%, the rate should be lower by mixing other non-reactive crushed- or natural aggregates. If it is obliged to use concrete aggregates all containing deleterious minerals in a discrete area, they must be used with low alkali cement Even if it is low quality in the chemical properties, aggregates with suitable range in the physical properties can be utilized as the aggregate of other purposes.

• 자원환경지질
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• 제44권2호
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• pp.171-180
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• 2011

화강암, 사암, 편마암으로 구성된 21개 암석시료를 대상으로 열전도도를 측정하고, XRD 정량분석을 통해 구성광물의 조성을 파악하였으며, 구조모델 이용하여 석영 함량 및 광물입자의 크기가 암석의 유효열전도도에 미치는 영향을 분석하였다. 측정된 열전도도는 석영 함량과 높은 상관성을 보여 ($R^2=0.75$), 석영 함량으로부터 열전도도를 추정할 수 있는 선형회귀모형을 제시하였다. 화강암 및 변성암 일부 시료의 경우 유사한 석영 함량에도 불구하고 열전도도가 크게 다른 값을 보였는데, 이는 주로 광물업자의 크기 변화와 관련이 있는 것으로 나타났다. 구조모델을 통한 분석 결과 입자의 크기가 작은 경우 열전도도는 scries와 EMT모델의 중간 영역에 해당하는 값을 보이며, 입자가 커지면서 EMT모델, ME모델을 거쳐 Parallel모델에 근접하게 변화하였다. 이러한 열전달 구조모델의 변화는 입자의 크기에 따른 열전도도 변화가 3 mm 두께의 원반시편을 이용하는 실험 규모와 관련이 있음을 시사한다. 즉, 얇은 원반 시료를 이용하여 암석의 열전도도를 측정할 경우 규모효과에 의하여 실제 지반의 값보다 과대평가될 가능성이 높으며, 특히 광물 입자의 크기가 클수록 이러한 오차는 더 커질 것으로 예상된다. 따라서 지열과 관련된 다양한 해석 모델에서 실험실 측정값을 실제 현장규모에서의 대표값으로 사용할 경우 모델의 예측 신뢰도에 영향을 줄 수 있는 요인으로 작용할 수 있다.

• 분석과학
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• 제37권2호
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• pp.79-86
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• 2024

Among the nutrients in feed, amino acids and minerals are important for the growth and development of pets. In particular, interest in nutritional components related to the health of pets is increasing as pet-raising households and pet food markets have recently grown. Therefore, in this study, 55 pet food products distributed in South Korea were purchased, and the content of 3 essential and conditionally essential amino acids (taurine, lysine, arginine) and 4 minerals (Ca, P, Na, K) was investigated. Among the three amino acids, arginine was found to have the highest content, and the average content was 1.79 and 1.37 % in cat and dog foods, respectively. On the other hand, the taurine content was the lowest, but it was found to be higher than the minimum requirement of 0.10 % for cats set by the American Association for Feed Control (AAFCO) and the European Federation of Pet Food Industries (FEDIAF). As a result of the four-component analysis of minerals, the content of Ca was found to be the highest, and the average content was confirmed to be 1.64 and 1.25 % in cat and dog food, respectively. On the other hand, Na was the lowest, but it was higher than the AAFCO minimum requirement and FEDIAF minimum requirement for young cat and dog food. Among all 55 samples examined, the content of the three amino acids and the four inorganic components was confirmed to be suitable for the recommended minimum intake and maximum allowable intake presented by AAFCO and FEDIAF.

• 한국식품영양과학회지
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• 제23권6호
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• pp.950-953
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• 1994

This study was carried out to investigate the proximate composition , free sugars,amino acids, organic acid, minerals and extracted color of the fruit of paper mulberry (Broussonetia Kazinoki Siebold) . the proximate compositins were 6.1% of moisture, 15.9% of crude protein, 28.5% of crude fat, 8.9% of crude ash and 40.6% of carbohydrates in the fruit of paper mulberry. Free sugars showed low content as 0.1% of glucose , 0.1% of sucrose, 0.1% of fructose and 0.01% of sorbitol, respectively. In amino acid composition of the fruit of paper mulberry, glycine was the highest in the content, followed by methionine, aspartic acid and alanine, The ratio of essential /total mino acids was 0.43 . The richestmineral contained in the fruit of paper mulberry was Ca and followed by K and Mg. Optical density (490-500nm) of the extracted color with 50% ehtanol and 80 % ethanol were 0.75 and 0.30 , respectively.

• 동아시아식생활학회지
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• 제25권5호
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• pp.867-879
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• 2015

To confirm basic nutrient contents of Korean honey as a food material, we assessed New Zealand Manuka honey by measuring proximate components, vitamin C and minerals of 16 kinds of honey harvested in South Korea. The proximate composition of each honey sample was as follows: moisture content 18.45~29.84%, crude protein 0.10~0.95% (vs Manuka honey 0.23%), crude fat 0.02~0.60% (vs Manuka honey 0.34%), crude ash 0.01~.52% (vs Manuka honey 0.24%) and carbohydrate 67.90~80.94% (vs Manuka honey 79.39%), respectively. In the case of free sugars analyze by HPLC, fructose showed a content of 26.12~49.84% which was highest in acacia honey and lowest in sorbus honey. Content of glucose was 19.38~36.12% and lowest in chestnut honey, whereas sucrose, lactose, maltose were absent. Total sugar contents were 64.16% which was less than Manuka honey (70.23%) and vitamin C was not detected in all samples. Minerals were detected 15~25 kinds, including K, Ca, Mg, Zn, Fe, Cu, Mo and so on. Ca was high in order of linden > canola > codonopsis > hedysarum honey, and K was higher than in Manuka honey in order of chestnut > hedysarum > codonopsis > jujube honey. Especially, these results suggest that Korean honey have a better nutrient content profile than Manuka honey.

• 한국광물학회지
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• 제3권1호
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• pp.34-43
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• 1990

Crystal-chemical study of hexagonal 7$\AA$ phyllomanganate minerals reveals that they have hexagonal layer structures with variable c dimensions which depend on the nature of interlayer cations and content of water molecules between edge-sharing [MnO6] octahedral layers. Approximately one out of nine octahedral sites is statistically vacant, leading to the general unit cell formula R2xMn4+1-xO2.nH2O, where R=Ca, Mn2+, Mg, K, Na;x=0.09-0.14 ; n-0.37-0.84. Z=1. The minerals of this formula fall under the name of rancieite group. It includes Ca-diminant (rancieite), Mn2+-dominant (takanelite), Na-dominant (birnessite), and Mg-dominant members. Minerals of the rancieite group occur predominantly in two different hydration states, i.e., n shows the values around 0.35 and 0.75. It is suggested that minerals of higher hydration state be called as species(i.e., rancieite, etc.) and those of lower hydration state be called as dehydrated varieties(i.e., dehydrated rancieite,etc.).

• 한국식품과학회지
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• 제10권2호
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• pp.258-262
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• 1978

Proximate composition, minerals and fatty acid in dried chicory root (moisture content 7.0%) are analyzed and subsequent results are as follows: Crude protein, crude fat, crude fiber, total sugar and ash content in chicory root are 8.6%, 1.6 %, 6.9%, 58.5% and 4.2%, respectively. Mineral content of Ca, P, Fe, Mg and Si in the root are 1,560, 180, 10,600 and 180 mg%, respectively. Other minerals such as K, Na, Al, Zn, Ag, Cu and Ti are also determined. Unsaturated fatty acid content in total fat of the root is 65.4%, Particularly high in linoleic acid. Uridine-5'-diphospho-glucose, as sole nucleotide-sugar in the root, was detected.

• 대한치과의사협회지
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• 제13권6호
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• pp.563-567
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• 1975

This present investigation was concerned with the content of collagen and minerals of incisor and molar dentin in rats of differednt ages. The results obtained were summarized as follows. 1. There was no remarked change in the content of collagen-hydroxyproline of incisor and molar dentin according to days after delivery. 2. The Ca content in incisor dentin rose from approximately 15.4% of the dry weight in 7 days after delivery to 21.1% in 22 days while that in molar dentin from 17.6% in 7 days to 19.7% in 22 days. 3. The P content in molar dentin rose from 8.5% in 7 days after delivery to 11.65% in 22 days. while in incisor rose from 8.05% in 7 days to 11.85 in 22 day after delivery.