• 한국식품저장유통학회지
• /
• 제11권4호
• /
• pp.496-502
• /
• 2004

도토리 가루를 알칼리로 침전시키면서 정제하여 도토리 전분을 얻었다. 다시 이 starch를 부탄올 개량법으로 분획하여 도토리 amylose와 amylopectin을 얻었고 Corn starch와 corn amylose, corn amylopectin은 시판되는 시약을 사용하였다. 이 시료들의 분자량 분포도를 관찰하기 위하여 GCP측정을 하였다. GCP측정은 DMSO와 DMF의 용매사용과 표준물질로 pullulan을 사용하여 검정하고 각 시료들의 지연시간으로부터 행하여졌다. 분자량분포도로부터 수평균분자량 (Mn)과 중량평균분자량(Mw) 및 다 분산도를 얻었다. 그 결과 acorn amylose와 corn amylose의 중량평균 분자량이 amylopectin에 비해서 뚜렷이 작게 나타나 ${\alpha}-1,4$ 선형결합을 갖는 amylose와 ${\alpha}-1,4$ 선형결합에 ${\alpha}-1,6$ 결합가지가 있는 amylopectin의 구조상의 차이를 확인할 수 있었다. 또한 분획한 acorn과 시판되는 corn과의 분자량분포도 측정을 비교한 결과 같은 경향을 나타내어 도토리 전분의 분획이 잘 이루어졌음을 확인하였다. 다분산도는 acorn starch와 corn starch 모두 amylose와 amylopectin에 비해 크게 나타났으며 이는 전분이 분획되기전 두 성분의 불균일성에 의한 성질로 분자량분포 범위가 넓게 나타났음을 알 수 있었다. 또한, 전단속도와 온도에 따르는 점도를 관찰하였더니 전단속도가 증가하면 점도는 감소하는 현상을 나타내는 pseudo plastic power law fluid 거동(13)을 보였으며 온도가 증가하면 점도는 지수 함수적으로 감소하였다.

• KSBB Journal
• /
• 제16권4호
• /
• pp.321-326
• /
• 2001

막의 특성을 이용하여 기질과 효소가 공존하는 캡슐을 제조하여 이 캡슐의 장점인 membrane의 pore size를 조절하면 올리고당을 분자량별로 유출시키는 것이 가능해짐으로 기질과 효소의 유출을 조절하여 생리활성이 높은 올리거당을 얻고, 생산된 올리고당의 단순한 분리.정제를 위하여, 그리고 효소의 재 이용 측면에서 encapsulation technology를 이용하여 올리고당을 생산하는 연구를 하였다. 제조된 capsule의 막 두께와 직경은 Olympus IX50 microscope를 이용하여 측정한 결과 막의 두께는 10 $\mu$m이었으며, capsule의 크기는 대략 3.0mm, $N_2$ gas를 이용할 capsule은 대fir 1.5 mm였다. 본 실험에 사용된 기질의 용액, 효소액, 반응액, alginate 용액을 pH 5.0으로 제조하여 사용하였기 때문에 막이 보다 견고하게 형성 할 수 있었으며, 제조된 capsule를 반응 용액 즉 2% acetic acid의 pH를 CaCO$_3$로 조절한 용액에 넣었기 때문에 막이 단단하게 형성되고 유지되는 것으로 판단된다. 기질의 사용에 있어서 작은 분자량을 갖는 기질은 효소와 분해 반응에 있어서 가수분해가 빨리 일어나기 때문에 보통 capsule 밖으로 유출된 올리고당의 분자량은 평균 M.W. 1,000이었다. 그러나 분자량이 큰 기질을 사용하였을 경우 평균 M.W. 1,000-3,500이었다. 막을 이루는 alginate의 점도에 의한 차이는 없었으며, 교반 속도에 의한 기질과 효소의 유출, 그리고 분해 반응에 따른 가수분해 산물인 올리고당의 유출에 있어 alginate 농도 0.5%, 교반 속도는 40 rpm이 가장 적당하였다. (12). Capsule에서 분해 반응 후 분해 산물인 올리고당의 이동을 빨리 하기 위하여 작은 size의 capsule를 제조하여 실험한 결과 3.0 mm보다 capsule 내부의 분자량 변화가 더 빨랐으며, capsule 밖으로 유출된 올리고당의 분자량 분석 결과 M.W. 3000-6000의 올리고당이 생성되었다. 반응 시간에 따른 capsule 내부의 잔류 효소 활성을 조사한 결과, 반응 8시간째에도 약 80% 이상의 효소활성을 나타내었다. Batch-type과 비교하여 capsule의 경우에는 반응이 끝난 후 capsule를 회수하여 효소를 재 사용할 수 있을 것으로 사료된다.

• 한국물환경학회지
• /
• 제39권6호
• /
• pp.465-474
• /
• 2023

The chemical composition and molecular weight characteristics of dissolved organic matter (DOM) exert a profound influence on the efficiency of organic matter removal in water treatment systems, acting as efficiency predictive indicators. This research evaluated the primary chemical and molecular weight properties of DOM derived from diverse sources, including rivers, lakes, and biomasses, and assessed their relationship with the efficiency of coagulation/flocculation treatments. Dissolved organic carbon (DOC) removal efficiency through coagulation/flocculation exhibited significant correlations with DOM's hydrophobic distribution, the ratio of humic-like to protein-like fluorescence, and the molecular weight associated with humic substances (HS). These findings suggest that the DOC removal rate in coagulation/flocculation processes is enhanced by a higher presence of HS in DOM, an increased influence of externally sourced DOM, and more presence of high molecular weight compounds. The results of this study further posit that the efficacy of water treatment processes can be more accurately predicted when considering multiple DOM characteristics rather than relying on a singular trait. Based on major results from this study, a predictive model for DOC removal efficiency by coagulation/flocculation was formulated as: 24.3 - 7.83 × (fluorescence index) + 0.089 × (hydrophilic distribution) + 0.102 × (HS molecular weight). This proposed model, coupled with supplementary monitoring of influent organic matter, has the potential to enhance the design and predictive accuracy for coagulation/flocculation treatments targeting DOC removal in future applications.

• Journal of Pharmaceutical Investigation
• /
• 제20권1호
• /
• pp.19-28
• /
• 1990

Pharmacokinetic parameters of aminoglycosides are dependent on renal function, sex, age, hematocrit, fever, lean body weight (LBW) and disease states, etc. Therefore, the individual pharmacokinetic parameters such as half life $(t^{1/2})$ and volume of distribution(Vd) are needed to achieve optimal therapy. However these parameters had not been determined in Koreans. The purpose of this study was to evaluate the Vd and $t^{1/2}$ of amikacin in Korean patients who had normal renal function, to compare the mean values of study group with that reported in the literature and to compare the measured $t^{1/2}$ with the expected $t^{1/2}$ based on actual body weight (ABW), LBW and ideal body weight (IBW), respectively. Based on data, the Vd was greater than the literature and $t^{1/2}$ was similar to the literature. The predicted $t^{1/2}$ based on IBW was the closest to actual $t^{1/2}$. And postpartum patients had greater Vd than other group and had lower correlation between actual elimination rate constant and calculated creatinine clearance but higher correlation between actual elimination rate constant and Vd than other group.

• 한국토양비료학회지
• /
• 제44권4호
• /
• pp.662-666
• /
• 2011

In this study, distribution characteristics of dioxins in soils in Busan, Korea were investigated regarding different land use types. Soil sampling sites that distributed through the Busan city showed dioxin concentration ranging from 0.489 to $322.736pg-TEQ\;g^{-1}$ dry weight with a mean value of $26.257pg-TEQ\;g^{-1}$ dry weight. The mean dioxin concentrations of investigated soils ranged from 1.554 to $50.357pg-TEQ\;g^{-1}$ dry weight in consideration of each land use type. That in metal refinery sites with $50.357pg-TEQ\;g^{-1}$ dry weight was higher than any other sites, followed by waste incinerator sites with $44.285pg-TEQ\;g^{-1}$ dry weight. The majority of soil samples had the same dioxin congener profiling despite the different range of dioxin concentration. Octa-CDD was the major contributor among seventeen dioxin congeners with the range from 29.5 to 70.1% in real values. In contrast to real values, dioxin congener profiles in TEQ values were dominated by 2,3,4,7,8-PeCDF which contributed about 35.3~43.8% to the total dioxin concentrations. It was judged by these results that penta-CDF was the major contributor of soil samples in Busan city. The mean ratio of PCDFs/PCDDs in real values was about 0.71, but that in TEQ values was, in contrast to it, approximately 3.03.

• 한국한의학연구원논문집
• /
• 제17권2호
• /
• pp.173-181
• /
• 2011

Objective : The purpose of this study is to evaluate the effect of Yuebijiashu-tang with Low-Glycemic Diet on the obesity and to improve the oriental medical methods of treatment in obesity patients. Methods : Forty one patients were classified into four groups(Normal, Overweight, 1st Obesity, 2nd Obesity) by Body Mass Index(BMI). Weight, Body Fat Mass, Body Fat Rate, Waist Hip Rate, BMI and Obesity Index were compared in each group by t-test. Results : In distribution of sex, male was 7(17.1%), female was 34(82.9%). Mean age was 37${\pm}$11 and the patients in twenties were the most. Among four groups, the number of 1st obesity groups was the most. In the change of body composition, the reduction of weight was 6.82${\pm}$2.67kg, the reduction of body fat mass was 5.53${\pm}$2.30kg, the reduction of BMI was $2.51{\pm}0.85kg/m^2$, the reduction of body fat rate was 4.61${\pm}$2.17%, the reduction of waist hip rate was 0.019${\pm}$0.013. Conclusion : This study shows that Yu$\'{e}$biji$\~{a}$sh$\`{u}$-t$\~{a}$ng with low-glycemic diet is effective on weight reduction.

• 한국재료학회지
• /
• 제29권4호
• /
• pp.233-240
• /
• 2019

This study analyzes the mechanical properties, including the attrition rate, of $50{\mu}m$ size yttria-stabilized zirconia (YSZ) beads with different microstructures and high-energy milling conditions. The yttria distribution in the grain and grain-boundary of the fully sintered beads relates closely to Vickers hardness and the attrition rate of the YSZ beads. Grain size, fractured surfaces, and yttrium distribution are analyzed by electronic microscopes. For standardization and a reliable comparison of the attrition rate of zirconia beads with different conditions, Zr content in milled ceramic powder is analyzed and calculated by X-ray Fluorescence Spectrometer(XRF) instead of directly measuring the weight change of milled YSZ beads. The beads with small grain sizes sintered at lower temperature exhibit a higher Vickers hardness and lower attrition rate. The attrition rate of $50{\mu}m$ YSZ beads is measured and compared with the various materials properties of ceramic powders used for high-energy milling. The attrition rate of beads appears to be closely related to the Vickers hardness of ceramic materials used for milling, and demonstrates more than a 10 times higher attrition rate with Alumina(Hv ~1650) powder than $BaTiO_3$ powder (Hv ~315).

• Advanced Composite Materials
• /
• 제18권2호
• /
• pp.121-134
• /
• 2009

The present study investigated, both experimentally and numerically, the improvement of low-velocity impact damage resistance of carbon fiber reinforced plastic (CFRP) laminates due to through-the-thickness stitching. First, we conducted drop-weight impact tests for stitched and unstitched laminates. The results of damage inspection confirmed that stitching did improve the impact damage resistance, and revealed that the improvement effect became greater as the impact energy increased. Moreover, the stitching affected the through-the-thickness damage distribution. Next, we performed FEM analysis and calculated the energy release rate of the delamination crack using the virtual crack closure technique (VCCT). The numerical results revealed that the stitching affected the through-the-thickness damage distribution because the stitch threads had a marked effect on decreasing both the modes I and II energy release rate around the bottom of the laminate. Comparison of the results for models that contained delaminations of various sizes revealed that the energy release rate became lower as delamination size increased; therefore the stitching improved the impact resistance more effectively when the impact energy was higher.

• Fibers and Polymers
• /
• 제5권2호
• /
• pp.89-94
• /
• 2004

N-Vinylcarbazole (VCZ) was solution-polymerized in tetrahydrofuran (THF) at 25, 35, and $45^{\circ}C$ using a room temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN); the effects of amount of solvent, polymerization temperature, and initiator concentration were investigated. On the whole, the experimental results corresponded to predicted ones. Room polymerization temperature using ADMVN proved to be successful in obtaining poly(N-vinylcarbazole) (PVCZ) of high molecular weight with small temperature rise during polymerization, nevertheless of free radical polymerization by azoinitiator. The polymerization rate of VCZ in THF was proportional to the 0.47 power of ADMVN concentration. The molecular weight was higher and the molecular weight distribution was narrower with PVCZ polymerized at lower temperatures. For PVCZ prepared in THF at $25^{\circ}C$ using ADMVN concentration of 0.00005 mol/mol of VCZ, weight-average molecular weight of 221,000 was obtained, with polydispersity index of 2.05, and degree of lightness converged to about 99%.

• 공업화학
• /
• 제10권3호
• /
• pp.432-437
• /
• 1999

폴리에틸렌 열분해실험을 반응기 크기가 $10cm^3$인 스테인레스 스틸 반응기에서 수행하였으며 이때 반응온도는 $390{\sim}450^{\circ}C$이었다. 열분해생성물인 반응생성물과 기체생성물을 분리하여 채취하였고 각 생성물의 분자량분포는 HPLC-GPC와 GC분석을 통해 얻었다. 열분해반응의 개시-종료, 전파-비전파반응, 즉 수소탈취반응, 사슬절단, 고분자물질과 라디칼과의 결합반응 등을 설명할 수 있는 random, specific 생성물의 분자랑분포에 대한 distribution balance식을 제안하였다. 말단절단 과정에 의해 저분자량의 비응축성 기체생성물 (C1~C5)이 생성되었으며 이 기체생성물의 평균분자량은 38이었다. 무작위절단과 말단절단의 속도매개변수 중의 하나인 활성화에너지는 각각 35, 17 kcal/mole 이었다.