• Bulletin of the Korean Chemical Society
• /
• 제25권10호
• /
• pp.1457-1458
• /
• 2004

• Bulletin of the Korean Chemical Society
• /
• 제26권6호
• /
• pp.979-982
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• 제29권12호
• /
• pp.2368-2372
• /
• 2008

• 대한화학회지
• /
• 제60권6호
• /
• pp.410-414
• /
• 2016

The anharmonic frequency of a local OH stretching mode of a water monomer and dimer was calculated using various levels of density functional theory. The quantum chemical potential energy curves as a function of the OH bond distance were calculated, and they were fitted with the Morse potential function to analytically obtain the fundamental transition frequency. By comparing those values with the frequencies similarly calculated using an ab initio quantum chemical method, the coupled cluster theory including both single and double excitations with the perturbative inclusion of triple excitation in the complete basis limit, the accuracy of various density functional methods in the calculation of anharmonic vibration frequency of water molecules was assessed. For a water monomer, X3LYP and B3LYP methods give the best accuracy, whereas for a water dimer, B972, LCBLYP, ${\omega}B97X$, ${\omega}B97$ methods show the best performance.

• Journal of Applied Biological Chemistry
• /
• 제50권2호
• /
• pp.70-73
• /
• 2007

Antioxidant and anti-diabetic activities of acorn were evaluated by its potential for scavenging stable DPPH free radical, inhibition of lipid peroxidation, reducing power, and inhibiton of ${\alpha}-glucosidase\;and\;{\alpha}-amylase$. The water extract of acorn exhibited strong antioxidant and antidiabetic related activities in the tested model systems. Solvent fractionation of the water extract revealed that the water fraction and the EtOAc fraction had strong antioxidant activity, and inhibitory activity on ${\alpha}-glucosidase\;and\;{\alpha}-amylase$. The water fraction exhibited higher DPPH radical scavenging activity ($EC_{50}=7.19{\mu}g/mL$) than that of ${\alpha}-tocopherol\;(EC_{50}=7.59{\mu}g/mL)$. It is considered that water extract of acorn has the potential for natural antioxidant and anti-diabetic products.

• 분석과학
• /
• 제10권6호
• /
• pp.459-467
• /
• 1997

Due to the growing demand for bottled mineral waters, a study was undertaken to determine the quality of the twenty six brands of domestic and imported drinking waters. The quality of water was evaluated by analyzing the twenty four elements including minerals, essential and/or toxic trace elements, and the analytical items to affect the taste of water. The contribution of drinking water to the mineral nutrition of human was calculated in order to investigate the health effect of drinking water. The taste of water was evaluated in terms of minerals, anions, TDS, alkalinity, hardness and pH.

• Bulletin of the Korean Chemical Society
• /
• 제12권3호
• /
• pp.334-342
• /
• 1991

To investigate the phase equilibria and structural properties of microemulsions, we study a simple phenomenological model on the basis of the cubic lattice cell with which the oil- and water-filled cells are connected one another, respectively. The surfactant is assumed to be insoluble in both oil and water, and to be adsorbed at the oil-water interface. The Schulman condition, according to which the lateral pressure of the surfactant layer is compensated by the oil-water interfacial tension, is found to hold to good approximation in the middle-phase microemulsion. Our results show that the oil- and water-filled domains in that microemulsion are about 50-150 $\AA$ across, and depend sensitively on the curvature parameters. The phase diagram is not symmetric in this model. It may be asymmetrized intrinsically by non-equivalency of oil and water. The two- and tree-phase equilibria including critical points and critical endpoints are found.

• 전기화학회지
• /
• 제26권2호
• /
• pp.19-34
• /
• 2023

Due to the intermittency of renewable energy sources, a need to store and transport energy will increase. Hydrogen production through water electrolysis will provide an excellent way to supplement the intermittency of renewable energy sources. While alkaline water electrolysis is currently the most mature technology, it has drawbacks of low current density, large footprint, gas crossover, etc. The PEM water electrolysis has potential to replace the alkaline electrolysis. However, expensive catalyst material used in the PEM electrolysis has been the bottleneck of widespread use. In this review, we have reviewed recent efforts to reduce catalyst loading in PEM water electrolysis. In core-shell nanostructures, the precious metal catalyst forms a shell while heteroatoms form a core. In this way, the catalyst loading can be significantly reduced while maintaining the catalytic activity. In another approach, a corrosion-resistant support is utilized, which provides a stable platform to impregnate precious metal catalyst.

• 멤브레인
• /
• 제33권6호
• /
• pp.369-376
• /
• 2023

본 연구에서는 에너지 소모가 큰 기존 진공 증류 공정의 대안으로 친환경이면서 에너지 효율적인 투과증발 분리공정을 이용하여 1,2 hexane diol/water (1,2 HDO/water) 혼합물에서 물을 분리하는 데 적용되었다. 사용한 분리막은 glutaraldehyde (GA)로 가교된 PVA를 알루미나 중공사 막(Al-HF) 내부에 코팅하여 사용하였다. 1,2 HDO/water 투과증발 분리공정에서는 PVA/GA 비율, 경화 온도 및 투과증발 분리공정 운전 조건에 대한 막의 최적화를 연구하였다. 장기 안정성 시험에서 PVA/GA (몰 비율 = 0.08, 경화 온도 = 80℃) 로 코팅된 Al-HF 막이 공정온도 40℃에서 1.90~2.16 kg/m²h 범위의 투과도를 보였으며, 투과용액의 수분 함량은 99.5% (separation factor = 68) 이상이었다.

• Bulletin of the Korean Chemical Society
• /
• 제35권5호
• /
• pp.1433-1439
• /
• 2014

We report on the influence of water as an electrolyte on the photovoltaic performances. The photovoltaic performance was shown to be quite sensitive to the substituent on the donor group. An optimized efficiency of 4.41% in the presence of 100% water content using $I^-/I{_3}^-$ redox couple was obtained using the D21L6 organic dye.