• 한국축산식품학회지
• /
• 제35권6호
• /
• pp.765-771
• /
• 2015

The development of a sample preparation method and optimization of the analytical instrumentation conditions were performed for the determination of the vitamin B₁₂ content in emulsified baby foods sold on the Korea market. After removal of the milk protein and fats by chloroform extraction and centrifugation, the vitamin B₁₂ was water extracted from the sample. Following filtration of the solution through a nylon filter, the water-soluble extract was purified by solid-phase extraction using a Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS). The solution eluted from the cartridge was dried under a stream of nitrogen gas and reconstituted with 1 mL of water. The sample solution was injected into an LC-MS/MS system after optimizing the mobile phase for vitamin B₁₂ detection. The calibration curve showed good linearity with the coefficient of correlation (r²) value of 0.9999. The limit of detection was 0.03 µg/L and the limit of quantitation was 0.1 µg/L. The method of detection limit was 0.02 µg/kg. The vitamin B₁₂ recovery from a spiking test was 99.62% for infant formula and 99.46% for cereal-based baby food. The sample preparation method developed in this study would be appropriate for the rapid determination of the vitamin B₁₂ content in infant formula and baby foods with emulsified milk characteristics. The ability to obtain stable results more quickly and efficiently would also allow governments to exercise a more extensive quality control inspection and monitoring of products expected to contain vitamin B₁₂. This method could be implemented in laboratories that require time and labor saving.

• 치과방사선
• /
• 제27권1호
• /
• pp.87-97
• /
• 1997

The purpose of this study was to evaluate the method for quantitative assessment of bone mass from aluminum-equivalent value of hydroxyapatite by using digital imaging system consisted of Power Macintosh 7200/120, 15-inch color monitor, and GT-9000 scanner with transparency unit. After aluminum-equivalent image made from correlation between aluminum thickness and grey scale, the accuracy of conversion to mass from aluminum-equivalent value was evaluated. Measured bone mass was compared with converted bone mass from aluminum-equivalent value of hydroxyapatite block by correlation formula between aluminum-equivalent value of hydroxyapatite block and hydroxyapatite mass. The results of this study were as follow; 1. Correlation between aluminum thickness and grey level for obtaining aluminum-equivalent image was high positively associated(r²=0.99). Converted masses from aluminum-equivalent value were very similar to measured masses. There was, statistically, no significant difference(P<0.05) between them 2. Correlation between hydroxyapatite aluminum-equivalent and hydroxyapatite mass was shown to linear relation (r²=0.95). 3. Converted masses from aluminum-equivalent value of 3 dry mandible segments were similar to measured masses. The difference between the exposure directions was not significantly different(P<0.05).

• 터널과지하공간
• /
• 제29권3호
• /
• pp.172-183
• /
• 2019

Hoek et al.(2002)이 개발한 일반화된 Hoek-Brown(GHB) 파괴기준식은 암반의 파괴응력 조건을 정의하는 비선형 함수이다. 관련 강도정수들은 GSI 지수값을 이용하여 체계적으로 결정된다. GSI 지수는 현장 암반의 상태를 정량화한 수치이므로 GHB 파괴기준식은 현장의 암반조건을 파괴기준식에 반영할 수 있는 실용적인 암반파괴함수이다. 대부분의 암반공학 기술자들이 선형 Mohr-Coulomb 파괴기준식에 익숙하며, 다수의 암반공학 소프트웨어들이 Mohr-Coulomb 식을 채택하고 있음을 고려하여 등가마찰각과 등가점착력 계산식이 GHB 파괴기준식 발표와 함께 제시되었다. 그러나 이 목적으로 제시된 등 가마찰각 및 등가점착력 계산식은 선형 최적화가 수행되는 최소주응력 범위의 하한 값을 암반의 인장강도로 고정시키고 있다. 따라서 해석영역에 인장응력이 분포하지 않은 경우 Hoek et al.(2002)의 제안식을 이용한 등가마찰각 및 등가점착력 산정결과는 정확성이 떨어질 수 있다. 이러한 기존 등가마찰각 및 등가점착력 산정수식의 단점을 극복하기 위하여 이 연구에서는 임의의 최소주응력 구간에 대해서도 최적 등가마찰각과 등가점착력을 계산할 수 있는 해석적 수식을 유도하고 결과식의 정확성을 검증하였다.

• Journal of Community Nutrition
• /
• 제4권2호
• /
• pp.99-108
• /
• 2002

Recently interests on raw-food diets are rapidly increasing in relation to chronic diseases prevention in Korea, but studies on raw-food diets have been hardly performed by nutritionists. This study was performed to investigate the effects of low-calorie diets using a raw-food formula in the form of freeze-dried powder on obesity and its complications in the obese women (body mass index (BMI) $\geq$ 25kg/㎡) for eight weeks. Forty premenopausal women (mean BMI 28.04kg/㎡, mean age 28.33years old) participated in this diet intervention, and were controlled by eating 1 regular meal, 1-2 snacks and 2 raw-food formula (140kcal/pack) meals a day within the 1500-1300kcal ranges. Anthropo-mentric measurements, body compositions, physical exercise, and obesity-related risk factors were assessed before (the initial), during (the 4th week) and after (the 8th week) the study. All the data was analyzed by paired t-test, repeated measures ANOVA, and nonparametric rank test at p<0.05 level. Obesity was significantly increased during this study, and it was decreased in weight (-4.59%, p<0.000), BMI (-4.56%, p<0.000), body fat percent (-6.18%, p<0.000), fat mass (-10.19%, p<0.000), waist and hip circumferences(-5.69%, p<0.000 and -2.55%, p<0.000) and WHR (-3.24%, p<0.000). Energy expenditure of physical exercise was increased as much as 70kca1/day during the study (p=0.000), but it did not have any correlations with weight loss and changes of body compositions. Biochemical measurements including blood triglyceride(p <0.006) and leptin(p<0.000) levels were significantly decreased, LDL cholesterol level was increased(p<0.05), but all the blood lipid levels were in the normal ranges. Fatty liver echogenicity and menstrual irregularity were improved after the diet intervention(p<0.000 and p<0.034). In conclusion, this B-week low-calorie diet intervention using raw-food formula was effective for obese premenopausal women in reducing obesity and its risk factors so as not to proceed towards comorbidities. However, the variation of blood lipid levels should be observed for a longer Period.

• Journal of Dairy Science and Biotechnology
• /
• 제25권1호
• /
• pp.55-60
• /
• 2007

국내 조제분유에서 초분 함량의 법적 기준 설정에 관한 과학적 근거를 살펴보고자 하였다. 국내 조제분유는 국제규격 CODEX와 미국 USDA등에서 다루고 있는 초분 또는 이물질에 대한 규격을 엄격히 따르고 있다. 그러나 국내 법규에서는 초분에 대한 용어 설명 및 성분 규격이 마련되어 있지 않아 초분에 관한 영유아식품의 안전성에 대해 사회적 관심이 점차 증가하고 있는 실정이다. 국내 조제분유 유래의 초분 조성과 함량을 SEM-EDS 분석법과 ICP-MS 분석법을 통해 확인하였다. 그 결과 초분의 미네랄은 조제분유에서 사용하는 원료 유래의 C, O, Ca, Na, Fe, Mg을 비롯한 미량 원소로 구성되어짐을 확인하였다. 조제분유는 원유, 탈지유, 유청분말, 혼합식물성 유지, 미네랄류 및 비타민류로 구성되어 있다. 국내 조제분유의 초분 함량은 국외 조제분유에서 보고되는 수준 또는 그 이하이며, 초분 유래 미량 성분으로서 중금속은 조제분유의 미네랄 공급원으로 사용되는 종류이다. 그러므로 국내 조제분유 내 초분의 조성과 함량은 FAO/WHO에서 설정한 잠정주당섭취량(PTWI)에 대하여 거의 영향을 주지 않는 것으로 사료된다.

• 한국공작기계학회논문집
• /
• 제11권5호
• /
• pp.88-92
• /
• 2002

This research is about slurry wear of SM45C and SUS304, which using standard sand and KUM river sand. The results are as follows ; 1. Mass loss rates of both standard sand and KUM river sand were linearly increased as increasement of time and velocity. 2. The average diameter of sand from relatively, less wear rate and portion of larger particles. 3. Wear resistance was linear with time and velocity of liquid jet regardless of type of sand. Also, it was able to evaluate with the formula, $HV^2$/E calibrated with n, the velocity index. 4. The wear surface in liquid jet experiment was smooth. The maximum wear depth was observed at the location 2~4mm apart from the center in the condition of $90^{\circ}$ of collision angle 6mm of nozzle diameter, and 20mm of collision distance. The sectional shape in radial appeared as 'W'shape.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.798-801
• /
• 2001

This research is about slurry wear of SM45C and SUS304, which using standard sand and KUM river sand. The results are as follows ; 1. Mass loss rates of both standard sand and KUM river sand were linearly increased as increasement of time and velocity. 2. The average diameter of sand from relatively, less wear rate and portion of larger particles. 3. Wear resistance was linear with time and velocity of liquid jet regardless of type of sand. Also it was able to evaluate with the formula, HV2/E calibrated with n, the velocity index. 4. The wear surface in liquid jet experiment was smooth. The maximum wear depth was observed at the location, 2~4mm apart from the center in the condition of 90$^{\circ}$of collision angle 6mm of nozzle diameter, and 20mm of collision distance. The sectional shape in radial appeared as 'W' shape.

• 대한조선학회논문집
• /
• 제45권3호
• /
• pp.309-314
• /
• 2008

An experimental method to estimate the added mass of a marine propeller has been developed for the axial rigid body motion in still water, and the experiments have been carried out. The experimental result has been compared to the theoretical result by PRODAS based on the unsteady lifting surface theory. The experimental method developed in this research and the theoretical method by PRODAS have been validated by confirming good agreements between the experimental results and the theoretical ones. Also the comparison to the results by empirical formula has been made and discussed.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.166-169
• /
• 2004

A fatigue test was used to evaluate the fatigue life of an actual structure. The loaded state and the constraint condition of an actual structure must be same as the specimen in order to apply the test results to an actual structure by the specimen. The loaded state and constraint conditions can't be same as the specimen in the actual structure which is complicated. In order to reduce these differences, an actual structure test with a lot of frequencies is need to get a fatigue life curve. Therefore, ten sets of accelerated test units which attached unbalanced mass were composed in this study. Acceleration history about the vibration of an actual structure was acquired. Rainflow counting was used on acceleration history, and the life curve return formula was assumed. The return formula that damage satisfied `1' was acquired in a feedback process by the Miner's rule, which was the linear cumulative damage theory. A conservative fatigue life curve was determined with a return formula to have been presumed by each set. The fatigue life of regular rpm condition was calculated by these conservative fatigue life curves.

• Earthquakes and Structures
• /
• 제14권4호
• /
• pp.305-312
• /
• 2018

Significant research efforts were undertaken to evaluate seismic performance of vertically irregular buildings on flat ground. However, there is scarcity of study on seismic performance of buildings on hill slopes. The present study attempts to investigate seismic behaviour of reinforced concrete irregular stepback building frames with different configurations on sloping ground. Based on extensive regression study of free vibration results of four hundred seventeen frames with varying ground slope, number of story and span number, a modification is proposed to the code based empirical fundamental time period estimation formula. The modification to the fundamental time period estimation formula is a simplified function of ground slope and a newly introduced equivalent height parameter to reflect the effect of stiffness and mass irregularity. The derived empirical formula is successfully validated with various combinations of slope and framing configurations of buildings. The correlation between the predicted and the actual time period obtained from the free vibration analysis results are in good agreement. The various statistical parameters e.g., the root mean square error, coefficient of determination, standard average error generally used for validation of such regression equations also ensure the prediction capability of the proposed empirical relation with reasonable accuracy.