• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.557-562
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• 2004

A surface-piercing barrier model is presented for understanding morphological development in the sheltered region and investigating the main factors causing the severe accumulation. Surface-piercing structures like vertical barriers, surface docks and floating breakwaters are recently favored from the point of view of a marine scenario since they do not in general partition the natural sea. The numerical solutions are compared with experimental data on wave profiles and morphological change rates within a rectangular harbor of a constant depth protected by surface-piercing thin breakwaters as a simplified problem. Our numerical study involves several modules: 1) wave dynamics analyzed by a plane-wave approximation, 2) suspended sediment transport combined with sediment erosion-deposition model, and 3) concurrent morphological changes. Scattering waves are solved by using a plane wave method without inclusion of evanescent modes. Evanescent modes are only considered in predicting the reflection ratio against the vertical barrier and energy losses due to vortex shedding from the lower edge of plate are taken into account. A new relationship to relate the near-bed concentration to the depth-mean concentration is presented by analyzing the vertical structure of concentration. The numerical solutions were also compared with experimental data on morphological changes within a rectangular harbor of constant water depth. Through the numerical experiments, the vortex-induced flow appears to be not ignorable in predicting the morphological changes although the immersion depth of a plate is not deep.

• 한국염색가공학회지
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• 제4권4호
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• pp.81-89
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• 1992

Graft polymers of alginic acid-PMMA, different in composition and Mv of branched PMMA, were prepared by emulsion graft polymerization at various MMA concentrations. In aqueous dispersion solution, the adsorption of graft polymer on the montmorillonite was carried out to modify the surface property of powder, and the adsorption of PMMA in organic solvents (acetone, benzene) on the modified surface of powder were observed. The results obtained were as follows. 1. In emulsion graft polymerization of MMA on the sodium alginate in aqueous solution, SA conversion, MMA conversion and % grafting were increased with increasing MMA concentration where as graft efficiency was decreased. 2. The adsorption amount of graft polymer was increased with the elevation of temperature and the increased of dispersion concentration and with the increase of branched PMMA composition of graft polymer. 3. In organic solvent, the adsorption of PMMA on the surface modified particle was proceeded by the orientation along the stretched branched PMMA of adsorbed graft polymer which is in radial direction to the particle surface. 4. The adsorbed amount of PMMA was increased as the temperature and concentration of PMMA solution, the branching of adsorbed graft polymer and the solvency of solvent were increased.

• 보존과학회지
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• 제38권1호
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• pp.64-71
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• 2022

Many investigations have been conducted on the biological damage and environmental conditions necessary to preserve the Janggyeong Panjeon and Daejanggyeongpan (woodblocks). We performed a survey on the concentration and diversity of airborne fungi in the Janggyeong Panjeon and compared them with the results of a survey from 2012. The temperature of the Beopbojeon building was slightly lower, while the relative humidity was higher than those found at the Sudarajang building. The concentration of airborne fungi in the Beopbojeon was 1.44-fold that of the Sudarajang. It was confirmed that the concentration and diversity of airborne fungi in the Janggyeong Panjeon differed depending on the sampling site. In total, 23 fungal genera were identified from the air samples, and 11 fungal and 1 bacterial genera were identified from the surface of the woodblocks. Among these, only five types of fungi were commonly distributed in the indoor air and surface of the Daejanggyeongpan; however, 58.3% of the fungi identified on the surface of the woodblocks were not observed in the in the air samples. The surface-dwelling fungi may accumulate dust to form microbial communities over time.

• 한국농공학회지
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• 제24권4호
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• pp.80-91
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• 1982

To precict the suspended sediments which are 80% of total sediments in a flood disch- arge, an equation representing vertical distribution of sediment concentration was derived based upon the diffusion theory and the logalithmic velocity distribution function in the tubulent flow mechanism. The hypothesis that the uniform mass transfer is occurred at upper part along the center line of water depth, was established as a preconition to solve the problem. The theorecal and the observed values were compared. And the theoretical equation was modified to be fit the theoretical values the observed values. Observed results are as follow; 1) Equation 12) is the theoretical equation representing the vertical concentration distri- bution of suspended sedimenta 2) Rous&exonential type vertical concentration distribution equation shows signification errors near the water surface. But the equation 12) shows substation cocentration values near the water surface. 3) Equation 15) is the modified theoretical equation which is possible to predict the vertical concentration distribution of suspended sediments.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 1999년도 추계학술발표회 초록집
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• pp.19-19
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• 1999

• 한국표면공학회지
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• 제53권2호
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• pp.59-66
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• 2020

Effects of Na₂SiO₃ concentration added into 0.1 M NaOH + 0.05 M NaF solution on the formation behavior and properties of PEO films on AZ91 Mg alloy were investigated under 1200 Hz of alternating current (AC) by voltage-time curves, in-situ observation of arc generation behavior and measurements of film thickness, surface roughness and micro vickers hardness. In the absence of Na₂SiO₃ in the 0.1 M NaOH + 0.05 M NaF solution, about 4 ㎛ thick PEO film was formed within 1 min and then PEO film did not grow but white spots were formed by local burning. Addition of Na₂SiO₃ up to 0.2 M caused more increased formation voltage and growth of PEO film with uniform generation of arcs. Addition of Na₂SiO₃ from 0.2 M to 0.4 M showed nearly the same voltage-time behavior and uniform arc generation. Addition of Na₂SiO₃ more than 0.5 M resulted in a decrease of formation voltage and non-uniform arc generation due to local burning. PEO film growth rate increased with increasing added Na₂SiO₃ concentration but maximum PEO film thickness was limited by local burning if added Na₂SiO₃ concentration is higher than 0.5 M. Surface roughness of PEO film increased with increasing added Na₂SiO₃ concentration and appeared to be proportional to the PEO film thickness. PEO film hardness increased with increasing added Na₂SiO₃ concentration and reached a steady-state value of about 930 H_V at more than 0.5 M of added Na₂SiO₃ concentration.

• 한국자원식물학회지
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• 제17권3호
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• pp.297-303
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• 2004

꼭두서니에서 추출한 염료를 이용해 몇 가지 조건에서 견직물을 천연염색 해 봄으로써 견직물에 대한 꼭두서니의 염색성과 염료로서의 이용성을 조사하였다. 꼭두서니 추출물로 모시 섬유를 염색 한 결과 표면색은 YR계열로 나타났으나 매염제에 따라 다소 차이가 있어 FeSO$_4$, SnC1$_4$, tartaric acid에서 는 Y계열로, 동백, 콩대재에서는 R계열로 나타났다. 염색온도에 따른 모시섬유의 표면색과 염착농도는 염색온도가 높을수록 a값이 증가한 반면에 b값은 감소되었고, L값은 낮아졌다. 염착농도는 7$0^{\circ}C$ , 9$0^{\circ}C$, 6$0^{\circ}C$순으로 높았다. 염액의 pH에 따른 표면색은 pH 4와 9에서는 순 Y계열을 나타냈으며, 염착농도는 산이 강할수록 K/S값이 다소 높게 나타났다. 염액의 농도에 따른 표면색은 농도에 관계없이 기본적으로 YR계 열로 발색 되었으며 , 염착농도는 염액의 농도가 높을 수록 증가하는 경향을 나타냈다. 염 색시간에 따른 표면색과 염착농도는 10-120분간에 큰 차이가 없어 10분간으로도 충분한 것으로 나타났다.

• 한국환경과학회지
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• 제26권2호
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• pp.147-157
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• 2017

This study investigated the characteristics of variations in carbon dioxide concentration and air temperature with the vertical change of surface in a grassplot. Field observations were carried out at a grassplot in Gyeongnam Science High School, over four days in August and November, 2015. Continuous observation equipment (GMP343, VAISALA) was installed at the LP (0.1 m from the surface) and UP (1.1 m from the surface) points, and the carbon dioxide concentration and air temperature were measured simultaneously at 1-min intervals. To summarize the results of the observation, August had higher than average concentrations of carbon dioxide, while November showed average air temperatures. Moreover, the concentration of carbon dioxide was higher at the UP point, while the air temperature was higher at the LP point. The correlation coefficient of carbon dioxide concentration between the UP and LP points was 0.80 in August across all the four days, while it was higher in November at 0.58-0.95. The results of the regression analysis of carbon dioxide concentration with air temperature changes for both August and November showed a distinct change at the LP point (R2=0.36-0.76), as compared to the UP point (R2=0.1-0.57). Between the UP and LP points, the carbon dioxide concentration and air temperature regression analysis results indicated that an active exchange was taking place between the two points.

• Food Science and Biotechnology
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• 제16권4호
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• pp.565-571
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• 2007

This study was carried out to investigate an optimum condition for the high angiotensin-l converting enzyme (ACE) inhibitory activity and the yield on enzyme concentration, casein concentration, and hydrolysis time. The optimum condition was performed by response surface methodology for acquirement of casein hydrolysate of milk which shows high ACE inhibitory activity, Among 8 tested enzymes, Protamex showed the highest activation degree with 77.03 unit/g from casein. Their hydrolysis degrees of flovourzyme 500MG, protamex, mixture from 1% casein were 85.5, 88.5, and 93.5%, respectively. The ranges of enzyme concentration (0.25-1.25%), casein concentration (2.5-12.5%), and hydrolysis time (20-100 min) as 3 independent variables through preliminary experiments of the yield of casein hydrolysate and ACE inhibitory activity, and it shows optimum response surface at a saddle point. It shows enzyme concentration (0.64%), casein concentration (8.38%), and hydrolysis time (55.81 min) in the yield aspect and showed the highest activity at enzyme concentration (0.86%), casein concentration (5.97%), and hydrolysis time (63.86 min) in ACE inhibitory aspect. The $R^2$ value of a fitted optimum formula on the hydrolysis yield was 0.9751 as the significant level of 1%. The $R^2$ value of a fitted optimum formula on ACE inhibitory activity is 0.8398, and the significance is recognized in the range of 5%.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.2883-2888
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• 2013

To enhance the power conversion efficiency of dye-sensitized solar cell (DSSC), the surface of titanium dioxide ($TiO_2$) photoelectrode was modified by hydroxylation treatment with $NH_4OH$ solution at $70^{\circ}C$ for 6 h. The $NH_4OH$ solutions of various concentrations were used to introduce the hydroxyl groups on $TiO_2$ surface. As the concentration of $NH_4OH$ was increased, the short-circuit current density ($J_{SC}$) value and conversion efficiency of solar cells were increased because the amount of adsorbed dye molecules on $TiO_2$ surface was increased. As a result of the surface modification to introduce hydroxyl groups, the concentration of adsorbed dye on the $TiO_2$ surface could be improved up to 32.61% without the changes of morphology, surface area and pore volume of particles. The morphology, the specific surface area, the pore volume and the chemical states of $TiO_2$ surface were characterized by using FE-SEM, $N_2$ adsorption-desorption isotherms and XPS measurements. The amount of adsorbed dye and the performance of fabricated cells were analyzed by using UV-Vis absorption spectroscopy and solar simulator.