• 전자공학회논문지
• /
• 제50권7호
• /
• pp.269-274
• /
• 2013

전해 산성이온수는 알칼리성 이온수에 비해 응용분야가 음용을 목적으로 하는 알칼리이온수와 많이 다르게 이용되고 있으며 ph 농도에 따라 강산성인 경우 잔류염소에 의한 살균 목적의 소독제로 사용되고, 중산성인 경우 세척과 세안으로 사용하고, 약산성인 경우 식재료와 혼합하여 요리에 널리 사용할 수 있다. 이런 산성이온수를 생성하기 위해서는 물을 전기분해 하여 사용하는데 전기분해 하는 과정에서 염소가스와 수산화나트륨 등의 물질로 살균력을 가지며, 전기분해시 +전극 쪽으로 -이온을 띤 염소, 인, 유황 등의 유기물이 모여져 산성이온수를 만든다. 또한 산성수와 알칼리수를 분리하기 위해서 격막을 사용했다. ph 농도변화의 구현방법은 Microprocessor를 이용하여 강산성에서 약산성 사이의 ph 농도를 PWM(pulse width modulation) 제어로 3종류의 PWM 전압을 전해조 전극에 인가하여 PWM제어에 의한 연속적으로 농도가 조절된 산성수가 생성되게 구현하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
• /
• pp.786-789
• /
• 1989

A nonlinear self-tuning regulator for a neutralization process of a weak acid and strong base system is proposed. Rearranging the state equation of the process model, we first obtain equations which are linear for a manipulated variable or unknown parameters. Then to these equations we apply the standard procedure used in designing linear self-tuning regulators. Simulation results show that the regulator provides very good performances for various realistic situations and traces variations of the unknown parameters. Since computations are simple and additional measurements except the effluent pH value are only flow rates of influent streams, it can be easily applied to real processes such as a waste water treatment process.

• Journal of the Korean Wood Science and Technology
• /
• 제46권2호
• /
• pp.155-165
• /
• 2018

The objective of the research was to evaluate the effect of particle pre-treatment on physical, mechanical, and durability of jatropha fruit hulls (JFH) particleboard. The pre-treatments included were immersing in cold water, hot water, and acetic acid solution. After each treatment, the particles were dried up to 3% moisture content. Urea-formaldehyde (UF) resin was used to fabricate particleboards with board size, thickness and density target of 25 cm by 25 cm, 0.80 cm, and $0.70g/cm^3$, respectively. Board pressed at $130^{\circ}C$ for 10 minutes, and $25kg/cm^2$ pressure. The evaluation of particleboard followed the JIS A 5908-2003. Whilist their resistance to subterranean termite test (mass loss, mortality, antifeedant value and feeding rate) refers to the Indonesian standard (SNI 01.7207-2006). The physical and mechanical properties of particleboards showed that all pre-treatments decreased the pH of particles. Overall, all particle immersing treatments resulted of better physical and mechanical properties of particleboard than those of untreated ones. The acetic acid treatment resulted the best physical and mechanical properties of particleboard. Based on the mass loss of JFH particleboard, hot water and acetic acid treated particleboards were classified into weak resistance to subterranean attack. The other two treatments were classified into very weak resistance. Hot water treated particleboard provided the highest mortality and antifeedant as much as 87.40% and 34.20%, respectively. Based on antifeedant classification, hot water treated particleboards were classified into moderately strong resistance, while other treatments were categorized into weak resistance. The lowest feeding rate value ($45.30{\mu}g/termite/day$) was attained by hot water treatment.

• 약학회지
• /
• 제22권4호
• /
• pp.193-200
• /
• 1978

Cholic, ursodesoxycholic, chenodesoxycholic, desoxycholic and hydesoxycholic acids were dissolved in the propylene glycol to make solution and then above solution of cholanic acids on bile secretion was investigated by injection those solutions into small intestine of rabbits and albino rats. The cholates in bile juice from rabbits injected with cholic acid were remarkably increased and therefore it exhibited a typical choleretic action. In view of pharmacological point, desoxycholic acid is considered as superior hydrocholeretic agent, and ursodesoxycholic and chenodesoxycholic acids have similar effect in decreasing order. However, the effect of bile secretion by hyodesoxycholic acid was almost negligible as that by propylene glycol administered. The cholate content in the bile juice from albino rat was increased by cholic and desoxycholic acids in decreasing order: i.e., they exhibited choleretic action. In the case of ursodesoxycholic and chenodesoxycholic acids, the concentration of cholate was slightly increased in bile juice from the rat, so that these cholates showed a weak choleretic action. While total output of bilirubin was increased by chenodesoxycholic acid, the other cholanic acid showed no effect in the rabbit.

• Journal of the Korean Wood Science and Technology
• /
• 제14권1호
• /
• pp.55-60
• /
• 1986

Discoloration sensitivities of woods grown in this country haven't reported yet. Therefore we examined discoloration sensitivities of domestic wood specimens to iron (0.1 %, $FeCl_3.6H_2O$), alkali (pH 12.0, NaOH). acid (pH 1.0, $C_2H_2O_4$) and exposing to sunlight (40 hrs), Thirty-six hardwood species were collected and examined. All specimens were prepared from heartwoods of the collected species. But the specimens of 4 Betula species were divided into sapwoods and heartwoods. By iron stain, the color differences (${\Delta}E$) of 21 wood specimens including one Betula sapwood showed above 12.0, which means strong discoloration sensitivities, and of 3 specimens including one Betula sapwood showed below 2.5, which means weak discolorations. The most strong iron discoloration species was Jungkukgulpi-namu (Pterocarya stenoptera). By alkali stain, the color differences (${\Delta}E$) of 3 wood specimens showed above 9.0, which means strong discoloration sensitivities, and of 18 wood specimens including 4 Berula sapwoods showed below 2.5, which means weak discolorations. By acid stain, the color differences (${\Delta}E$) of 6 wood specimens showed above 10.0 which means strong discoloration sensitivities, and of 12 wood specimens including one Betula sapwoods showed below 2.5, which means weak discolorations. By exposing to sunlight, the color differences (${\Delta}E$) of 31 wood specimens including one Betula sapwoods showed below 6.5, which means, strong discoloration sensitivities, and of only one specimens showed below 2.5, which means weak discoloration. The most strong discoloration species by exposing to sunlight was Guirung-namu (Prunus padus). In general, it was shown that hardwoods grown in Korea were most subject to change of color by exposing to sunlight and next were by iron stain. Domestic hardwoods showed some differences in discoloration sensitivities from domestic softwoods previously reported.

• Restorative Dentistry and Endodontics
• /
• 제17권1호
• /
• pp.115-125
• /
• 1992

It is advisable to use irrigation solutions which have strong antibacterial effect and weak cytotoxic effect on treating root infections. Streptococci are ones of the most frequently isolated microorganisms in infected root canals. The antibacterial effect of ten irrigation solutions were investigated on S. mutans (19449), S. sanguis. )10556) and 4 streptococci isolated from saliva of healthy persons. These streptococci were exposured to irrigation solutions during 10 sec, 30 sec,. 1 min, 3 min, 5 min, 10 min, 30 min and 2hrs respectively. Four irrigation solutions which showed strong antibacterial activity were diluted to 1 : 1 to 1 : 10,000. Then they were subcultured on blood agar plate an observed after 1 day. 5.25% NaOC1 had the strongest antibacterial effect. 30% urea and normal saline showed no antibacterial effect. 50 % citric acid and 3% $H_2O_2$ showed relatively weak antibacterial effect. 15 % EDTA had very weak antibacterial effect.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2003년도 봄 학술발표회 논문집
• /
• pp.481-484
• /
• 2003

Sulfide minerals contacted with air and water in coal seam cause oxidation reactions. This oxidation reactions make low pH of groundwater and surface water(Acid Drainage). The reddish brown precipitate collected from the cut slope of the study area was estimated using the X-Ray Diffractometer(XRD). XRD results show that the cut slope was affected by Acid Drainage. The cut slope exposured to Acid Drainage become weak about chemical weathering and defile the appearance of the road. Drainage facilities are very important in Cut Slope under Acid Drainage influence. Reactions between Coal seam and water cause chemical weathering and environmental problem. Therefore It is important to control the transfer paths of groundwater and surface water and to install water collecting facilities

• 산업기술연구
• /
• 제21권A호
• /
• pp.17-26
• /
• 2001

The fatigue strength of SM55C has significantly decreased by 83% compared with atmosphere where distilled exists due to strong erosive action of acid fog. The reason is inferred in a way that strong acid erosive material such as acid fog act and give rise to multi-site crack on the surface. Several fatigue clacks occurred under the acid fog repeat the process of division and unification on the surface and form a long non-propagating crack throughout the circumference of experimented steel. However, in the depth, many parts do not show much trace of unification, and the depth is not as big as the one of normal crack shape. 10% of $CaCl_2$ causes strong erosive reaction to material. Then eventually make the life of fatigue shooter. On the other hand, 20% of $CaCl_2$ beings about oxidized material organic crack closing due to weak erosive reaction.

• 한국식품영양학회지
• /
• 제6권1호
• /
• pp.47-52
• /
• 1993

In the present study, an attempt was made to investigate the effect of oleic acid on the autoxidation of the commercial rice bran oil. Rice bran oil samples with oleic acid at 0.1, 0.3 and 0.5% level were kept at 45 $\pm$ 0.3$^{\circ}C$ for 40 days. The rate of autoxidation of each samples was estimated regularly on the basis of the changes of peroxide value, acid value, anisidine value and the fatty acid composition. The per oxide, acid and anisidine values of the rice bran oil with the oleic acid increased as compared with that of the rice bran oil without the oleic acid during the autoxidation. The induction period of the rice bran oil without the oleic acid, control was 19.8 days, while those of the rice bran oil with oleic acid at 0.1, 0.3 and 0.5% levels were 18.3 days, 16.8 days, and 15.5 days, respectively. In conclusion, it seemed that oleic acid acted as weak prooxidant when added at 0.1, 0.3 and 0.5% levels to the commercial rice bran oil.

• 한국식품영양학회지
• /
• 제4권2호
• /
• pp.167-174
• /
• 1991

In the present study, an attempt was made to Investigate the effect of stearic acid on the autoxidation of the commercial rice bran oil, Rice bran oil samples with stearic acid at 0.1, 0.3 and 0.5oh level were kept at 45$\pm$0.3$^{\circ}C$ for 40 days. The rate of autoxidation of each samples was estimated regularly on the basis of the changes of peroxide value, acid value, anisidine value and the fatty acid composition. The results were as follows : The peroxide, acid and anisidine values of the rice bran oil with the stearic acid at 0.1, 0.3 and 0.591 levels during the autoxidation Increased as compared with that of the rice bran oil without the stearic acid. The induction period of the rice bran oil without the stearic acid, control was 19.0days, while those of the bran oil with stearic acid at 0.1, 0.3 and 0.5% levels varied 19.0 days, 17.7days and 14.2 days, respectively. In conclusion, it seemed that stearic acid acted as weak prooxidant when added at 0.1, 0.3 and 0.5% levels to the commercial rice bran oil. The prooxidant activity of the stearic acid appeared to depend on the oxidative mechanism and their concentration.