• 한국수소및신에너지학회논문집
• /
• 제10권1호
• /
• pp.9-17
• /
• 1999

기계적인 합금처리된 여러 Mg-Ni 혼합물 중에서 가장 우수한 수소저장 성질을 가지고 있는 Mg-25wt.%Ni 혼합물의 수소화물 형성 및 분해 반응에 대한 반응속도론적 연구를 하였다. 수소화물 형성 및 분해 속도를 측정하여 이론적인 반응 속도식과 비교함으로써 율속 단계를 결정하였다. Mg-25wt.%Ni의 수소화물 형성의 율속단계는 $H_a$ = 4.0 미만의 여러 $H_a$ 범위에서는 입자간 통로 (interparticle channel), 입자의 갈라진 틈(crack) 등을 통한 수소 분자의 이동 단계인 Knudsen 유동과 보통의 기체 확산이고, 4.0 < $H_a{\leq}4.25$ 범위에서는 성장하는 수소화물 층을 통한 수소 원자의 확산으로 생각된다. Mg-25wt.%Ni의 수소화물 분해의 율속 단계는 전 $H_d$ 범위에 걸쳐 수소 분자의 이동 단계인 Knusden 유동과 보통의 기체 확산이다.

• BMB Reports
• /
• 제38권5호
• /
• pp.584-590
• /
• 2005

Glucose 6-phosphate dehydrogenase (EC 1.1.1.49) was purified from Aspergillus aculeatus, a filamentous fungus previously isolated from infected tongue of a patient. The enzyme, apparently homogeneous, had a specific activity of $220\;units\;mg^{-1}$/, a molecular weight of $105,000{\pm}5,000$ Dal by gel filtration and subunit size of $52,000{\pm}1,100$ Dal by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The substrate specificity was extremely strict, with glucose 6-phosphate (G6P) being oxidized by nicotinamide adenine dinucleotide phosphate (NADP) only. At assay pH of 7.5, the enzyme had $K_m$ values of $6\;{\mu}m$ and $75\;{\mu}m$ for NADP and G6P respectively. The $k_{cat}$ was $83\;s^{-1}$. Steady-state kinetics at pH 7.5 produced converging linear Lineweaver-Burk plots as expected for ternary-complex mechanism. The patterns of product and dead-end inhibition suggested that the enzyme can bind NADP and G6P separately to form a binary complex, indicating a random-order mechanism. The enzyme was irreversibly inactivated by heat in a linear fashion, with G6P providing a degree of protection. Phosphoenolpyruvate (PEP), adenosinetriphosphate (ATP), and fructose 6-phosphate (F6P), in decreasing order, are effective inhibitors. Zinc and Cobalt ions were effective inhibitors although cobalt ion was more potent; the two divalent metals were competitive inhibitors with respect to G6P, with $K_i$ values of $6.6\;{\mu}m$ and $4.7\;{\mu}m$ respectively. It is proposed that inhibition by divalent metal ions, at low NADPH /NADP ratio, is another means of controlling pentosephosphate pathway.

• 한국표면공학회지
• /
• 제44권1호
• /
• pp.13-20
• /
• 2011

This study investigated the high temperature oxidation behavior of Fe-22%Cr-5.8%Al alloy and the oxidation kinetics of the alloy were discussed. Bulk samples were prepared by VAM (vacuum arc melting) and hot forging. High temperature oxidation testes were isothermally conducted up to 100 hours in 79%$N_2$+21%$O_2$ environment at three different temperatures ($900^{\circ}C$, $1000^{\circ}C$, $1100^{\circ}C$). The weight gain was measured after oxidation according to oxidation time (2, 4, 6, 8, 10, 15, 20, 25, 30, 60, 80, 100 hours). The weight gain significantly increased with increasing oxidation temperature. As the temperature increased, the oxidized samples showed sequential formation of $Al_2O_3$, Cr-rich oxide, Fe-rich oxide. The activation energy of high temperature oxidation was obtained as 306.63 KJ/mol. $Al_2O_3$ were developed on the surface in the early stage of oxidation, representing protective role of oxidation. However, Fe-based and Cr-based oxides leaded to breakaway of oxide layer, thus resulted in the significant increase of additional oxidation.

• Journal of Animal Science and Technology
• /
• 제59권10호
• /
• pp.22.1-22.7
• /
• 2017

Background: Very limited information exists on the ruminal degradation kinetics of nutrients in garlic stalk. The present study aimed to survey the annual yield of garlic stalk in Korea and determine its feed-nutritive value for ruminants. Methods: In Experiment 1, garlic stalk was incubated in situ in the rumen of two Hanwoo steers ($360{\pm}15kg$ body weight) and removed after 12, 24, or 48 h to determine the ruminal degradation kinetics of DM and NDF. Rice straw was also included for comparison. In Experiment 2, In Experiment 2, six male Corriedale sheep were randomized to two dietary treatments to determine the apparent digestibility of nutrients in garlic stalk. Diets included a control ration without garlic stalk (60% concentrate mix +40% ryegrass) or a treatment ration (70% control diet +30% garlic stalk). Results: The Korean national yield of garlic stalk (sun-dried basis) in 2016 was estimated to be 31,910 tons, with the southern coastal regions producing the highest quantity. Compared with rice straw, garlic stalk had lower NDF, higher ADF, and greater effective degradabilities of DM and NDF, resulting in a greater TDN value (56.3%), which was higher than that obtained for rice straw (43.7%). Conclusion: These results provide basic information on the ruminal DM and NDF degradation kinetics of garlic stalk, which would be helpful for the efficient utilization of this by-product in ruminant diets

• Biomaterials and Biomechanics in Bioengineering
• /
• 제1권2호
• /
• pp.105-116
• /
• 2014

Synthesis of interpenetrating polymer network (IPN) of chitosan-gelatin (Cs-Ge) (as a primary network) and N-isopropylacrylamide (NIPAAm) monomer (as the secondary network) was carried out with different ratio. Its structure was characterized by FT-IR, which indicated that the IPN was formed. The memberanes were studied by swelling, weight loss with time. The interior morphology of the IPN hydrogels was revealed by scanning electron microscopy (SEM); the IPN hydrogels showed a interpenetrated network of NIPAAm/chitosan has layers with more minute stoma and canals compared to interpenetrated network of NIPAAm/gelatin. Lower critical solution temperature (LCST), equilibrium swelling ratio (ESR) and deswelling kinetics were measured. The DSC results noticed that LCST of IPN hydrogels with different ratio of Cs/Ge/PNIPAAm are around $33{\pm}2^{\circ}C$. The ESR obtained results showed that with a ratio of Cs/Ge/NIPAAm: 1/1/6, the swelling ratio increased drastically from room temperature to $36^{\circ}C$ but with a ratio of Cs/Ge/PNIPAAm: 1/3/6, decrease significantly at the same condition. Therefore the hydrogels have been changed from a hydrophilic structure to a hydrophobic structure. Furthermore with an increase in temperature from room to the LCST, the ESR of IPN with higher concentration of (PNIPAAm) and (Ge) decreases but de-swelling kinetics of them are faster. Due to the suitable and different kinetics of de-swelling and the equilibrium swelling ratio (ESR) in various proportions, and because of the morphology inside the mass which confirms other tests, these hydrogels are very appropriate as a smart thermosensitive hydrogels with rapid response.

• Elastomers and Composites
• /
• 제34권1호
• /
• pp.3-10
• /
• 1999

아크릴로니트릴(AN) 단일중합체를 항온장치가 부착된 광중합반응기내에서 합성하여 최적반응조건하에서 중합속도모델식을 구하였다. AN의 농도($1.8{\sim}7.58mo1/1$), 증감제의 종류($NaSCN,\;KSCN,\;Ba(SCN)_2,\;NH_4SCN,\;ZnCl_2,\;Na_2SeO_3$) 및 농도($10{\sim}60%$), 반응온도($10{\sim}70^{\circ}C$), 에너지 세기($1,000{\sim}9,900{\mu}J/cm^2$)를 변화시켰다. 광증감제의 농도에 관계없이 반응온도 $50^{\circ}C$, 반응시간 3시간에서 균일한 분자량분포를 얻고, 이중 광증감제로 50%의 NaSCN의 경우 다음과 같은 중합속도 모델식을 구하였다. $R_p=0.0142[M]^{0.82}[I]^{0.49}[S]^{0.52}$ exp(-1.33/RT).

• 유기물자원화
• /
• 제15권1호
• /
• pp.134-142
• /
• 2007

본 연구는 생활쓰레기의 물리 화학적 분석 및 발열량 등으로 그 특성을 알고 반응기를 이용한 열중량감량 분석을 함으로써 열처리 시설의 가장 효율적인 운영에 기초자료가 됨을 목적으로 한다. 측정 결과는 다음과 같다. 쓰레기의 삼성분 중 가연분이 약 61%로 다른 수분(약 32%) 회분(약 7%)보다 함유량이 높았고 쓰레기의 원소분서결과 종류에 관계없이 탄소와 수고(약 94%)의 존재량이 대부분이었다. 쓰레기의 발열량 분석 결과 고위발열량은 2897.883(Kcal/kg)의 값을 갖는 것으로 나타났다. TGA를 이용하여 도시 생활쓰레기의 종류별 열적 특성을 분석한 결과 온도가 증가함에 따라서 시로 중에 함유된 휘발분이 지속적으로 무게 감량이 일어났으며 특히 $300{\sim}500^{\circ}C$에서 열중감량이 활발히 진행되고 그 반응속도에 차이가 있음을 알 수 있었다.

• 환경위생공학
• /
• 제14권3호
• /
• pp.63-70
• /
• 1999

A study on the zeolite synthesized of bituminous coal fly ash from power plant has been carried out to reuse industrial waste. The synthesized zeolite was proved to be 4A type by means of the X-ray diffraction analysis and the degree of crystallinity was found to be higher than 90%. Then the synthesized zeolite was used as an adsorbent to remove the heavy metal ions in the CU, Pb, and Cd containing wastewater and water. Also, adsorption characteristics and kinetics of synthesized zeolite in the each metal ion solutions were studied. In each ion solutions, the adsorbed amounts of Pb, Cd, and Cu to the unit weight of synthesized zeolite were 141.6, 118.8, and 131.4mg/g respectively when each metal ion concentration was 500mg/L solution. The adsorption kinetics was fitted well to the Freundlich isotherms. The value of l/n for Pb, Cd, and Cu and 0.27, 0.50, and 0.66, respectively. Those results showed that the synthesized zeolite could be used as an adsorbent to remove single heavy metal ions in the wastewater and water. The heats of adsorption, H values of Pb, Cd, and Cu were 4.87, 14.95, and 18.23kacl/mol by the Henry-van't Hoff equation.

• 대한기계학회논문집
• /
• 제18권8호
• /
• pp.2101-2112
• /
• 1994

A two-dimensional biomechanical model was developed in order to calculated the lower extremity kinematics and kinetics during level walking. This model consists of three segments : the thigh, calf, and foot. Each segment was assumed to be a rigid body ; its motion to be planar in the sagittal plane. Five young males were involved in the gait experiment and their anthropometric data were measured for the calculation of segmental masses and moments of inertial. Six markers were used to obtain the kinematic data of the right lower extremity for at least three trials of walking at 1.0m/s, and simultaneously a Kistler force plate was used to obtain the foot-floor reaction data. Based on the experimental data acquired for the stance phase of the right foot, calculated vertical joint forces reached up to 0.91, 1.05, and 1.11 BW(body weight) at the hip, the knee, the ankle joints, respectively. The flexion-extension moments reached up to 69.7, 52.3, and 98.8 Nm in magnitude at the corresponding three joints. It was found that the calculated joint loadings of a subject were statistically the same for all his three trials, but not the same for all five subjects involved in the gait study.

• Journal of Pharmaceutical Investigation
• /
• 제25권1호
• /
• pp.47-54
• /
• 1995

Transdermal patch formulations of estradiol to treat post-menopausal symptoms and prevent osteoporosis in women were developed and evaluated for the permeation characteristics through the excised hairless mouse abdorminal skin and the uterotropic effect on the ovariectomized rabbits. The design of patch formulations was optimized by varying several formulation parameters, such as type of enhancers, amount of enhancers, amount of drug loading and coating thickness. Compared to a commercially available transdermal product, several patch formulations showed the similar skin permeation profiles (following zero-order kinetics), but their skin permeation rates were lasted for the longer period (a week). In one-week uterotropic efficacy test in the ovariectimized rabbits, the selected patch formulations showed the positive effect in atrophy of the urogenital epithelium. The mean values of uterus weight in rabbits after application of patches containing estradiol were much higher than those in control group (containing no drug).