• 기술사
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• 제18권4호
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• pp.12-22
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• 1985

This investigation was attempted to determine changes in chlorophyll. Pheophytin content PH and titratable acidity during young redish Kim chi fermentation. Young redishes divied in to leaf and vein and fermented in dark room for 35 days at 10$^{\circ}C$ after pickling each group. Samples were collected at 5 days interval for the chemical analysis. The following results were obtained. 1. Chlorophyll content in young redish was decreased by decreasing PH during fermentation periods. Chlorophyll content decreased from 11.60mg/g to 7.62mg/g in leaf, from 0.48mg/g to 0.33mg/g in vein respectively during 35 days fermentation periods. In contrast to chlorophyll. pheophytin content increased as chlorophyll content decreased during the period. The ratio of chlorophyll a and b content in young redish about 3 : 1 in leaf and vein and decreased nearly the same ratio during fermentation periods. In case of pheophytin a and b it was increased without any relation with the ratio chlorophyll a and b. In generally, the optimum PH for eating was known 4.3 to 5.0. Young redish Kim chi was reached the optimun PH at 15 to 25 days of fermentation at 10$^{\circ}C$. At this periods. Chlorophyll content varied from 11.32mg/g to 9.30mg/g for leaf and from 0.43mg/g to 3.37mg/g for vein, respectively. 2. Titratable acidity(as lactic acid) was increased to 0.54% in leaf at 20 days fermentation period during Kim chi fermentation. and nearly unchanged until 30days. At the end of fermentation period the titratable acidity was about 0.30％. Titratable acidity was increased as decreasing pH. and the correlation coefficients was -0.92 in leaf and -0.77 in Vien. 3. Correlation between titratable acidity and chlorophll, pheophytin content was not significant statistically.

• 한국세라믹학회지
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• 제34권7호
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• pp.738-746
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• 1997

MgO clinker and two kinds of dolomite clinkers with different microstructures and CaO contents were used as starting materials, and the effects of Fe2O3 addition on the properties of MgO and dolomite were investigated in the range of 2 to 8 wt% of Fe2O3 content. Secondary phases contributed to densification of MgO-Fe2O3 and dolomite-Fe2O3 were magnesioferrite and dicalciumferrite, respectively. Sinterabilities of MgO-Fe2O3 and dolomite-Fe2O3 were directly proportional to the amount of secondary phases. Also, sinterability of dolomite itself was dependent on the microstructure of starting material including distribution of CaO and MgO as well as the addition amount of Fe2O3. The flexural strength of MgO-Fe2O3 content was almost constant. The hydration resistance of dolomite with large size of MgO and discontinuous distribution of CaO was higher than that of dolomite with small size of MgO and continuous distribution of CaO. Also, the minimum content of Fe2O3 to prevent they hydration of dolomite was about 4wt%. As increasing Fe2O3 content, the penetration resistance of MgO-Fe2O3 was improved by the increment of magnesioferrite. On the other hand, the penetration resistance of dolomite-Fe2O3 was decreased because of the increment of dicalciumferrite having low melting point.

• 한국잠사곤충학회지
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• 제40권1호
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• pp.13-16
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• 1998

From mulberry root bark of 13 various varieties, ${\gamma}$-Aminnobutyric acid(GABA) contents were examined on HPLC analyzer. GABA contents in mulberry root bark were affected by genotypes. Average GABA content of the 13 mulberry varieties was 2.19 mg/gDW. GABA content of the varieties ranged from 1.70 to 2.62 mg/gDW. Among the three genotypes, GABA content of the Morus Lhou was higher than the other genotype. In GABA content Hongolppong was the highest with 2.62 mg/gDW on the 13 varieties of mulberry root bark.

• 한국주조공학회지
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• 제33권3호
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• pp.103-112
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• 2013

Effect of Fe and Mn contents on the tensile properties of Al-4 wt%Mg-0.9 wt%Si alloy system has been studied. Common phases of Al-4 wt%Mg-0.9 wt%Si alloy system were ${\alpha}$-Al, $Mg_2Si$, ${\alpha}-Al_{12}(Fe,Mn)_3Si$ and ${\beta}-Al_5FeSi$. As Fe content of Al-4 wt%Mg-0.9 wt%Si alloy system increased from 0.15 wt% to above 0.3 wt%, ${\beta}-Al_5FeSi$ compound appeared. When Mn content of the alloy increased from 0.3 wt% to 0.5 wt%, morphology of plate shaped ${\beta}-Al_5FeSi$ compound changed to chinese script ${\alpha}-Al_{12}(Fe,Mn)_3Si$. As Fe content of Al-4 wt%Mg-0.9 wt%Si-0.3 wt%Mn alloy increased from 0.15 wt% to 0.4 wt%, tensile strength of the as-cast alloy decreased from 191 MPa to 183 MPa and, elongation of the alloy also decreased from 8.0% to 6.2%. Decrease of these properties can be explained as the formation of plate shape, ${\beta}-Al_5FeSi$ phase with low Mn/Fe ratio of the alloy. However, when Mn content of Al-4 wt%Mg-0.9 wt%Si-0.3 wt%Fe alloy increased from 0.3 wt% to 0.5 wt%, tensile strength of as-cast alloy increased from 181 MPa to 194 MPa and, elongation of the alloy increased from 6.8% to 7.0%. These improvements attribute to the morphology change from ${\beta}-Al_5FeSi$ phase to chinese script, ${\alpha}-Al_{15}(Fe,Mn)_3Si_2$ phase shape-modified from with high Mn/Fe ratio of the alloy.

• Nutrition Research and Practice
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• 제7권2호
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• pp.82-88
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• 2013

Eleven types of nuts and seeds were analyzed to determine their energy (326-733 mg), moisture (1.6-18.3 mg), carbohydrate (8.8-70.9 mg), protein (4.9-30.5 mg), lipid (2.5-69.8 mg), and ash (1.2-5.5 mg) contents per 100 g of sample. Energy content was highest in pine nuts (733 mg/100 g), carbohydrate level was highest in dried figs (70.9 mg/100 g) and protein was highest in peanuts (30.5 mg/100 g). The amino acid compositions of nuts and seeds were characterized by the dominance of hydrophobic (range = 1,348.6-10,284.6 mg), hydrophilic (range = 341.1-3,244.3 mg), acidic (range = 956.1-8,426.5 mg), and basic (range = 408.6-4,738.5 mg) amino acids. Monounsaturated fatty acids (MUFA) were highest in macadamia nuts (81.3%), whereas polyunsaturated fatty acids (PUFA) were highest in the walnuts (76.7%). Macadamia nuts did not contain any vitamin E, whereas sunflower seeds contained the highest level (60.3 mg/kg). Iron (Fe) content was highest in pumpkin seeds ($95.85{\pm}33.01$ ppm), zinc (Zn) content was highest in pistachios ($67.24{\pm}30.25$ ppm), copper (Cu) content was greatest in walnuts ($25.45{\pm}21.51$ ppm), and lead (Pb) content was greatest in wheat nuts ($25.49{\pm}4.64$ ppm), significantly (P < 0.05). In conclusion, current commercial nuts and seeds have no safety concerns, although further analysis of Pb contents is necessary to ensure safety.

• 한국주조공학회지
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• 제1권3호
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• pp.14-18
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• 1981

The Mg-loss of AlSi 7% melts containing from 0 to 0.8% Mg during the Hexachloroethane tablet degassing was investigated. The results of the experiment was discussed in view of the free energy change and kinetics of $MgCl_2$ formation. The melts with Mg content less than 0.5% showed a Mg-loss proportional to Mg-content, while it was constant at about 24% of the weight of tablets, when Mg content of the melt became more than 0.5 %. The rate of Mg-loss was drastically reduced, when the amount of tablets used at a time increased ver a certain limit for a given melt quantity.

• 한국재료학회지
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• 제22권1호
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• pp.54-60
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• 2012

The particle size of MgO was examined as a function of the Na content in $Mg(OH)_2$ powders and the calcination temperature. $Mg(OH)_2$ suspension was obtained by dropwise precipitation of $Mg(NO_3)_2{\cdot}6H_2O$ and NaOH solutions. The suspension was diluted by varying the dilution volume ratio of distilled water to $Mg(OH)_2$ suspension to change the Na salt concentration in the suspension. $Mg(OH)_2$ slurry was filtered and dried at $60^{\circ}C$ under vacuum, and then its $Mg(OH)_2$ powder was calcined to produce MgO with different amount of Na content at $500\sim900^{\circ}C$ under air. Investigation of the physical and chemical properties of the various MgO powders with dilution ratio and calcination temperature variation was done by X-ray diffraction, transmission electron microscopy, BET specific surface area and thermal gravimetric analysis. It was observed that MgO particle size could depend on the condition of calcination temperature and dilution ratio of the $Mg(OH)_2$ suspension. The particle size of the MgO depends on the Na content remaining in the $Mg(OH)_2$ powder, which powder was prepared by changing the dilution ratio of the $Mg(OH)_2$ suspension. This change increased as the calcination temperature increased and decreased as the dilution ratio increased. The growth of MgO particle size according to the increase of temperature was more effective when there was a relatively high content of Na. The increase of Na content lowered the temperature at which decomposition of $Mg(OH)_2$ to MgO took place, thereby promoting the crystal growth of MgO.

• 한국식품저장유통학회지
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• 제13권2호
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• pp.228-233
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• 2006

본 연구는 뜰보리수의 영양성분의 함량과 성숙 증에 이들 변화를 조사하여 식품학적 가치를 평가하고자 하였다. 들보리수의 수분함량은 성숙함에 따라 감소하였고 당도 (brix)는 증가하는 경향이었다. 탄수화물(무질소화합물)은 성숙함에 따라 증가하였으나 조단백질의 함량은 감소하였다. 환원당의 함량은 수용성 단백질과 달리 성숙중에 증가 하였다. 유리당 함량은fructose와 glucose의 함량이 높았으며, 이들의 함량은 성숙 중에 현저하게 증가하였다. 미숙과 실의 총 유리당의 함량은 135.66 mg/100 g-fr.wt 이었으나 완숙과 과숙과실에서는 각각 544.26. 787.83 mg/100 g-fr.wt 으로 급격히 증가하였다. 유기산의 조성은 acetic, citric, lactic, malic, succinic acid 이었으며, citric acid의 함량이 가장 높았다. 총유기산의 함량은 미숙 과실일때 407.95 mg/100 g-fr.wt이었고, 성숙 중에 급격하게 감소하였다. 환원형 비타민 C의 함량은 미숙 과실일 때 56.98 mg/100 g-fr.wt이었으며, 성숙 중에 감소하는 경향이었고, 총 비타민 C의 함량도 성숙 중에 감소하였다. 폴리페놀의 함량은 411.39 mg/100 g-fr.wt이었으며, 완숙과에서는 293.41 mg/100 g-fr.wt으로 성숙 중에 현저히 감소하였다.

• 한국염색가공학회지
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• 제31권3호
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• pp.177-186
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• 2019

In this study, we investigated for synthetic hydrotalcite in chloroprene rubber foam. Experiments were carried out to find the optimum content ratio by controlling the contents of MgO and Hydrotalcite. Swelling test in toluene immersion was made to measure the crosslinking density of CR foams, and the cure properties were investigated with flat die rheometer and Mooney viscosity. The difference of hardness, tensile strength and elongation at break were observed after immersing in 7% NaCl or 21% NaCl solutions for a day and four days. In addition, the volume change and water content remaining in CR foam were measured after immersing NaCl solution. As content of MgO increased, the value of the cure torque tended to increase, but it was almost constant above 2phr of MgO. However, the Mooney viscosity decreased with increasing MgO content. The crosslinking density, determined by the swelling ratio, showed that the CR compound without MgO showed a higher degree of swelling. When the content of hydrotalcite/MgO was 3:2, it was the lowest volume change of CR form. Also, As the content of hydrotalcite decreased, the difference of mechanical properties before and after immersion NaCl solution increased.

• 한국식품위생안전성학회지
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• 제38권6호
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• pp.537-543
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• 2023

본 연구에서는 대형마트, 편의점 및 온라인 마켓에서 수집한 조제커피 제품의 카페인 함량을 모니터링하고 표시사항의 적합성을 검토하고자 하였다. 카페인의 함량은 HPLC을 사용하여 정량 분석하였다. 그 결과, 콜드브루 제품의 카페인 함량은 0.31-1.04 mg이었으며 평균 0.55 mg으로 나타났다. 제품 1개당 평균 함량은 147.27 mg/bottle로 나타나, 일일 권장섭취량을 감안하였을 때 성인 1인당 2.7병을 섭취할 수 있다. 아메리카노 제품의 카페인 함량은 0.15-0.38 mg이었으며 평균 함량은 0.28 mg 수준으로 나타났다. 제품 1개당 평균 함량은 110.42 mg/bottle로 나타나, 일일 권장섭취량을 감안하였을 때 성인 1인당 3.6병을 섭취할 수 있는 것으로 나타났다. 디카페인 콜드브루 제품의 카페인 평균 함량은 5.14 mg/bottle로 나타났으며 일반 아메리카노 제품에 비해 약 95%이상 카페인이 제거되어 식품의약품안전처에서 제시한 디카페인 제품 기준에 충족하였다. 또한, 총 카페인 함량의 허용오차인 120%를 초과하지 않아 관리가 잘 이루어지고 있음을 확인하였다.