• Korean Journal of Food Science and Technology
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• 제30권1호
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• pp.42-48
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• 1998

Physicochemical properties of waxy maize starch and oxidized waxy maize starch with sodium hypochlorite $(0{\sim}60\;mg\;CL_2/g\;starch,40^{\circ}C,\;pH\;10,\;3.0\;hr)$ were studied. As sodium hypochlorite concentration was increased, the content of crude lipid and crude protein of the oxidized starch were decreased. And crude protein content and whiteness was considered to show negative regression. However, the crude ash content of the oxidized starch increased significantly with oxidation and bore a positive regression to the chlorine content. There was a progressive increase in the carboxyl content with increasing oxidant level. After pasting in hot water and cooling, viscosity of the oxidized starches were drastically lower than that of native starch . As carboxyl contents of the oxidized starch increased, the solubility and swelling power was increased. When waxy maize starch treated with 0, 1.5, 3.0 and 6.0% sodium hypochlorite, temperature of initial gelatinization of oxidized starch was shown to 65, 65, 60 and $50^{\circ}C$, respectively. The oxidized waxy maize starches also form clearer pastes. Water binding capacity of the oxidized starch decreased as the degree of carboxyl group substitution increased. Waxy maize starch has polygonal and some round granules which range from about 3.7 to $20\;{\mu}m$ in diameter. Surface appearance of the waxy maize starch became rough when oxidized with sodium hypochlorite. When homogenate of the oxidized waxy maize starch solution and corn germ oil was stored under room temperature for 24 hours, the emulsion stability was considered to depend on starch concentration and degree of substitution.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.29.1-29.1
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• 2018

양극산화 표면처리 방법의 일종인 플라즈마 전해산화(PEO, Plasma electrolytic oxidation)는 금속 소재에 양극 전압을 인가하여 고경도의 산화 피막을 금속 표면에 형성시키는 표면처리 기술이다. PEO 공정은 피막의 국부적 유전체 파괴에 의한 아크의 발생을 동반하며, 형성된 산화 피막이 아크 발생에 의한 높은 열에 의해 결정화 되어 일반적인 양극산화 피막보다 우수한 경도와 내마모성을 가진다. 하지만 PEO 공정은 고전압을 필요로 하여 일반적인 양극산화 처리보다 소모되는 전력량이 많으며, 아크 발생에 의해 형성된 피막의 표면 거칠기가 높기 때문에 활용 분야가 제한되거나 후속 연마 공정을 필요로 하는 단점이 존재한다. 본 연구에서는 전류 파형이 알루미늄 합금의 플라즈마 전해산화 피막의 형성 거동에 미치는 영향을 직류 및 펄스전류를 사용하여 연구하였다. NaOH 및 $Na_2SiO_3$가 혼합된 전해액에서 직류 전류 밀도, 전압, 펄스폭을 달리하여 알루미늄 합금에 전류를 인가할 때 발생되는 아크의 거동, 형성된 산화 피막의 두께, 거칠기, 경도, 표면 및 단면 구조를 비교 분석하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.132.2-132.2
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• 2017

플라즈마 전해 산화(Plasma Electrolytic Oxidation, PEO)는 Al, Ti, Mg 합금과 같은 경량 금속소재에 대한 표면처리기술로서 주목을 받고 있다. PEO 처리에 의해 표면에 치밀하게 형성되는 세라믹 산화층은 우수한 내식성, 내마모성을 보유하기 때문에, 이와 같은 특성이 요구되는 분야에 적용하기 위한 연구가 활발하다. 특히 PEO 세라믹 코팅층의 응착마모(adhesive wear)와 절삭마모(abrasive wear)에 관한 연구는 상당부분 이루어지고 있으나, 캐비테이션 침식과 같은 침식마모(erosive wear) 특성에 관한 연구는 부족한 실정이다. 본 연구에서는 알루미늄 합금 소지에 제작된 PEO 코팅층의 캐비테이션 손상 특성을 고찰하였으며, 전해액 조성이 PEO 코팅층의 미세조직과 캐비테이션 손상 특성에 미치는 영향을 살펴보았다. PEO 처리를 위해 사용된 소재는 상용 5083-O합금 판재로서 $2cm{\times}2cm$로 절단하여, 에머리페이퍼로 1000번까지 연마하여 사용하였다. 사용된 전해액은 증류수에 KOH(1 g/L)을 base로 하여 $Na_2SiO_3$(2 g/L)의 첨가유무를 변수로 하였다. 시편을 양극으로 하고 STS304를 음극으로 하여 각각 DC 전원 공급기의 +극과 -극에 연결하였으며, 정전류 조건에서 30분간 $0.1A/cm^2$의 전류밀도를 인가하였다. PEO 처리후 시편은 SEM, EDS, XRD를 이용하여 표면 특성 평가를 실시하였다. PEO코팅층의 캐비테이션 특성 평가는 초음파 진동식 캐비테이션 발생 장치를 이용하였으며, 캐비테이션 실험 후 시간에 따른 표면 거칠기의 변화 거동을 분석하였다.

• Korean Journal of Food Science and Technology
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• 제27권2호
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• pp.225-229
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• 1995

Soy oligosaccharide, a low calorie sugar, which is known to improve the intestinal microbial flora, was recovered from the waste of soymilk process by Steffen process. To remove protein contaminants, prior to the Steffen process, pH of the sample was adjusted to $3.5{\sim}4.0$ or calcium chloride was added 8%(w/w) per sugar. Both pretreatment processes were found to remove about $25{\sim}30%$ of the protein initially present in the sample. Using the Steffen process, as much as 85% of soy oligosaccharide could be recovered as a saccharate form. The amounts of calcium chloride and lime used were 20%(w/w) and $100{\sim}120%$(w/w) per total sugar, respectively. After the sugar was desorbed by $CO_{2}$, the final yield of oligosaccharide was 80% while 80% of protein were removed from the original solution. The composition of sugar was similar to that of soybean cooking water.

• Korean Journal of Food Science and Technology
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• 제45권3호
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• pp.350-355
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• 2013

The quality of fermented dropwort extract (FDE) and fermented dropwort vinegar (FDV) was assessed for free sugar, organic acid and free and total amino acid content. Major organic acids were lactic acid in FDE and acetic acid in FDV. Free sugars in FDE were fructose and glucose, and those in FDV were fructose, sucrose, and maltose. Aspartic acid was the major free amino acid in both FDE and FDV. Additionally, the main free amino acids in FDE were alanine and ${\gamma}$-amino-n-butyric acid (GABA), while those in FDV were arginine and valine. Moreover, to investigate the protective effects of FDE and FDV against oxidative stress induced by t-BHP and $H_2O_2$, C6 cells were treated with FDE or FDV prior to inducing the oxidative damage. FDE and FDV inhibited cell death significantly in a dose-dependent manner. These data imply that FDE and FDV may be effective in neuronal cell protection against oxidative damage.

• Proceedings of the Korean Aquaculture Society Conference
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• 한국양식학회 2001년도 추계 한국양식학회 학술대회
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• pp.275-276
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• 2001

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 한국표면공학회 2007년도 추계학술대회 논문집
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• pp.30-30
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• 2007

• Proceedings of the Korean Radioactive Waste Society Conference
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• 한국방사성폐기물학회 2012년도 춘계학술논문요약집
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• pp.209-210
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• 2012

• Journal of the Korea Institute of Information and Communication Engineering
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• 제14권4호
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• pp.923-928
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• 2010

Anodic aluminum oxide (AAO) nanotemplates for nano electronic device applications have been attracting increasing interest because of ease of fabrication, low cost process, and possible fabrication in large area. The size and density of the nanostructured materials can be controlled by changing the pore diameter and the pole density of AAO nanotemplate. In this paper, nano porous alumina films AAO nanotemplate was fabricated by second anodization method using sputterd Al films. In addition, effects of electrolyte temperature and anodization voltate on the microstructure of porous alumina films were investigated. As the electrolyte temperature was increased from $8^{\circ}C$ to $20^{\circ}C$, the growth rate of nanoporous alumina films was increased from 86.2 nm/min to 179.5 nm/min. The AAO nanotemplate fabricated with optimal condition had the mean pore diameter of 70 nm and the pore depth of $1\;{\mu}m$.

• Resources Recycling
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• 제33권1호
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• pp.31-36
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• 2024

The separation of Ag and Zn from the nitrate leachate of spent silver oxide batteries using Cyanex272 as an extractant was investigated. The extraction of Ag and Zn was affected by the concentrations of nitric acid and the extractant. Cyanex-272 selectively extracted Zn over Ag when the HNO₃ concentration was lower than 0.1 mol/L. The co-extracted Ag was removed by stripping with 1 mol/L thiourea. Stripping of Zn from the loaded Cyanex-272 was accomplished using 0.5 mol/L HNO₃ after the removal of Ag. The McCabe-Thiele diagrams for the extraction of Zn with Cyanex-272, the scrubbing tripping of Ag with thiourea, and the stripping of Zn with HNO₃ were constructed. The results were verified by simulated counter-current extraction and stripping experiments. Finally, a process for the separation of Ag and Zn from silver oxide batteries was proposed.