• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.1
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• pp.123-132
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• 2002

The literature often mentions the hardness of water in dampening solutions as possible source of problem. In most literature describes that the water hardness affects print quality. However water hardness affects not only print quality, but also emulsification of ink and dampening solution. Therefore the purpose of this study was to determine if water hardness actually affects the emulsification rate of dampening solution and ink. And this study for the factors determining the emulsion velocity, we have measured water pick-up and calculated emulsion velocity constant 'k' and activation energy.

• Journal of Korean Society on Water Environment
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• v.30 no.1
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• pp.25-30
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• 2014

This study is done to prove the premise that both alkalinity and hardness affect on the dissolved phosphorus concentration so that the growth of algae is also affected in water bodies like rivers and lakes. Statistical analysis of the water quality data of 13 reservoirs collected for the last decade shows the relations between alkalinity and chlorophyll-${\alpha}$ and between hardness and chlorophyll-${\alpha}$ are not linear but follow second order equation. This relation seems to be due to two antagonistic effects accompanying a simultaneous increase in alkalinity and hardness. The increase stimulates the growth of algae by supplying carbonates and $Ca^{2+}$ to algae and at same time it causes a decrease in soluble phosphorus which retards algae to grow. These opposing tendencies are confirmed by theoretical calculations with the MINTEQ model. There seems to be ranges of alkalinity and hardness that are in favor of algae growth; the ranges are less than 44 mg/L as $CaCO_3$ in alkalinity and also less than 63 mg/L as $CaCO_3$ in hardness. This finding will provide a solid base to develop an effective water quality management of water bodies.

• Journal of Sericultural and Entomological Science
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• v.13 no.1
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• pp.49-59
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• 1971

This experiment was conducted, how making use of "Seracol 100", a kind of nonionic surface active reagent, during cocoon cooking and silk reeling process which is mainly used in Korea and developed by one of the authors since 1965. Main purpose of the experiment is to investigate the influence of the activity of the reelability aid reagent on various degree of hardness component and various salts which are contained in filature water being used by silk factories now. Specifically, it was tried to determine the effects of the reelability aid reagent added to each sample water of artificially differentiated the degree of hardness component upon sericin solubility. Some of the major findings are summarized as follows. 1. "Seracol 100", with below 5$^{\circ}$dH water, increased sericin solubility in each sample water, but above $10^{\circ}$dH the effect of it shows a significant relationship with the different degree of hardness component. Besides the component (MgCO$_3$)$_4$ㆍMg(OH)$_2$, generally, the higher the degree of hardness in the water, the less the amount of desolved sericin in the water showed. There is little or no difference between 1000 times diluted "Seracol 100" water and 2000 times diluted "Seracol 100" water in terms of sericin solubility. 2. The different kind of degree of hardness component shows a significant relationship with sericin solubility, In case use of "Seracol 100", Mg hardness component affected on the sericin solubility more than Ca hardness. But in the control, contrary to this, that is Ca hardness component did more than Mg hardness, 3. The different kind of salts in degree of hardness component show a significant relationship with sericin solubility. In the control water, nitrate is the greatest among salts affecting on sericin solubility, next chloride and sulfate are in order. In case of "Seracol 100" water, chloride is the least among salts, below $10^{\circ}$dH, next sulfate and nitrate are in order, and above 15$^{\circ}$dH, next nitrate and sulfate are in order. 4. In case of "Seracol 100" water, the more contained heavy metal salts (Fe, Al, Cu, Mn) in the water, the less sericin solubility showed. It is found that there is little or no difference among other salts in terms of sericin solubility. But alkaline metal salt remarkably increased sericin solubility. 5. In case of "Seracol 100" water, tinting of the water was affected by Ca salts more than by Mg salts. Among other salts, only Al and Fe affected on the tinting of the water, specifically, in view of the fact that "Seracol 100" water increase the tinting of Fe salt water, but decrease the tinting of raw silk. It is thought that "Seracol 100" deter Fe$^{+2}$ from absorbing to raw silk by deteriorating the activity of Fe$^{+2}$ . 6. "Seracol 100" have the effect on osmosis of the water, After treatment until 2hrs the osmosis of 1000 times diluted "Seracol 100" water is the greatest, next orders are 2000 times diluted "Seracol 100" and control. From 2 hrs to 6 hrs the osmosis of 2000 times diluted water is the greatest, next orders are 1000 times diluted water and control. After 6 hrs the osmosis of the water is the same order as above. 7. In view of tile fact that "Seracol 100" have the effect to control the degree of hardness during the treatment of cocoon layer in the water, it is thought that, in varying degree of hardness in the water, there is a significant relationship between "Seracol 100" and degree of hardness components in cocoon layer.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.515-518
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• 2006

This paper presents the friction and wear characteristics of contact type sealing unit for a water turbine of a small hydro-power generation, which Is to stop a leakage of a circulating water from a outside of an impeller to an inside of a rolling bearing. The surface wear strongly affect to the seal life of a mechanical face seal. In this study, the hardness of a stainless steel in which is a heat-treated is 892.8 in Vickers hardness and the hardness of silicone carbide of SiC is 714.1 in Vickers hardness. The surface hardness of a heat-treated stainless steel is 25% high compared with that of a ceramic material of SiC. The contact modes of rubbing surfaces aye a dry friction a water film friction and a mixed friction that is contaminated by a dust, silt and moistures, etc. These two factors of a contact rubbing modes and a material property are very important parameters on the tribological performance such as a friction and wear between a seal ring and a seal seat. The experimental result shows that the surface hardness of a seal material is very important on the friction coefficient and a wear volume. Thus, the results recommend higher hardness of a seal material, which may reduce a friction loss and increase a wear life of primary seal components

• KIEAE Journal
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• v.16 no.3
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• pp.83-88
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• 2016

Purpose : This study aimed to verify the surface hardness and water repellency of earth paint manufactured with earth, a natural material, and provide the results as basic data for paint made with natural materials. Method : After presenting the accurate manufacturing methods for basic materials for paint, the authors conducted and analyzed experiments to evaluate surface hardness and water repellency, fundamental performance indicators for paint, based on different mixture ratios. From the results of the experiment to assess the surface hardness of flour-based earth paint, we observed high surface hardness only after painting the specimen three times. Since potato starch-based earth paint has higher viscosity than its flour-based counterpart, the former did not paint well on the first occasion, resulting in low surface hardness. After painting two or more times, however, it was observed to have higher surface hardness than flour-based earth paint. Result : It was found that at least three iterations of painting was required to obtain high surface hardness of potato starch-based earth paint. Furthermore, the results of the water resistance experiment of earth paint suggest that the use of environment-friendly finishing materials coupled with boiled linseed oil will mitigate the drawbacks of earth paint. The experiment with one-year-old specimens also demonstrated similar water repellent characteristics, which indicates that the performance will improve once the paint has dried for a sufficient period of time.

• Transactions of Materials Processing
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• v.31 no.4
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• pp.207-213
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• 2022

In this study, variations in the microstructure and hardness of a low-carbon SCM415 steel with austenitizing temperature and cooling rate are investigated. When the austenitizing temperature is lower than the A₁ temperature (738.8 ℃) of the SCM415 steel, the microstructures of both the air-cooled and water-cooled specimens consist of ferrite and pearlite, which are similar to the microstructure of the initial specimen. When heat treatment is conducted at temperatures ranging from the A₁ temperature to the A₃ temperature (822.4 ℃), the microstructure of the specimen changes depending on the temperature and cooling rate. The specimens air- and water-cooled from 750 ℃ consist of ferrite and pearlite, whereas the specimen water-cooled from 800 ℃ consists of ferrite and martensite. At a temperature higher than the A₃ temperature, the air-cooled specimens consist of ferrite and pearlite, whereas the water-cooled specimens consist of martensite. At 650 ℃ and 700 ℃, which are lower than the A₁ temperature, the hardness decreases irrespective of the cooling rate due to the ferrite coarsening and pearlite spheroidization. At 750 ℃ or higher, the air-cooled specimens have smaller grain sizes than the initial specimen, but they have lower hardness than the initial specimen owing to the increased interlamellar spacing of pearlite. At 800 ℃ or higher, martensitic transformation occurs during water cooling, which results in a significant increase in hardness. The specimens water-cooled from 850 ℃ and 950 ℃ have a complete martensite structure, and the specimen water-cooled from 850 ℃ has a higher hardness than that water-cooled from 950 ℃ because of the smaller size of prior austenite grains.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.51-64
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• 1988

It has been suggested that calcium is only one of many metals that compete with toxic metals in the body. Therefore, this study was carried out to determine the influence of water hardness on accumulation of heavy metals in rats. The seventy-five rats were divided into control and case groups. Case group was subdivided into four subgroups in proportion to the concentration of water hardness respectively, such as, 0, 250, 500, 1000ppm. Control group was fed on only deionized water, but case groups were fed on hard water with ionized heavy metals (Cd 150mg + Pb 300mg + Cu 300mg/l) for 20, 40, 60 days. The concentrations of cadmium, lead and copper were measured by atomic absorption spectrophotometry (Perkin Elmer 2380) in livers and kidneys. The results of the study are summarized as following 1. The concentration of cadmium accumulation showed the tendency of decrease in proportion to water hardness in both livers and kidneys of rats having been fed for only 60 days, respectively. 2. In only livers of rats having been fed for 60 days, essential metal, copper had the tendency of decrease according as hardness in water. 3. It was impossible to compare case with control about the tendency of lead accumulation because there was no difference between the two in livers and kidneys respectively.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.17-30
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• 1984

This study was done to evaluate the hardness, water sorption and solubility values of twelve well known composite resins, and to compare each other. For the hardness test, the specimens were made in cylinder form with 4mm in diameter and 2mm in thickness as a modification of the American Society for Testing and New Materials, 1966, and for water sorption and solubility tests, the specimens were prepared in same shape of 20mm in diameter and 0.5mm in thickness as a modification of the ADA Specification No. 12. The results were obtained as follow: 1. The hardness range were from 17.9 to 87.5 respectively. As time passed by, the noticable change was evident in early 12 hours. 2. Of the water sorption. the range was from 0.38 to 0.93. The significant change was appeared within 12 hours and on 3 day by 1 week except four brands. 3. Of the water solubility, the range was 0.06 to 0.16. The highest value was found within early 24 hours. 4. Generally, four brands could be chosen as preferable products of hardness. water sorption and solubility tests according to the ADA Specification No. 12.

• Journal of Veterinary Science
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• v.23 no.5
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• pp.64.1-64.9
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• 2022

Background: Fluralaner is a novel drug belonging to the isoxazoline class that acts on external parasites of domestic animals. It is used systemically via drinking water, especially against red poultry mite in layer chickens. Fluralaner is frequently used in layers infected with D. gallinae. However, no study to date has investigated the effects of feed intake and water hardness. Objectives: This study aimed to investigate the effects of variable water hardness and feed intake on the pharmacokinetic profile of fluralaner. Methods: Layer chickens were divided into four groups (n = 8): fed + purified water (Group 1), feed restricted + purified water (Group 2), feed restricted + hard water (Group 3), and feed restricted + soft water (Group 4). After administering a single dose of the drug with drinking water, the blood samples were collected for 21 days. Fluralaner concentrations in plasma samples were determined by liquid chromatography/tandem mass spectrometry. The maximum plasma concentration (C_max), time to reach maximum plasma concentration (t_max), area under the concentration-time curve values (AUC_0-21d), half-life (t_1/2), and other pharmacokinetic parameters were calculated. Results: Although the highest maximum plasma concentration (C_max) was determined in Group 1 (fed + purified water), no statistically significant difference was found in the C_max, t_max, t_1/2, MRT_{0-inf_obs}, Vz/F_obs, and Cl/F_{_obs} parameters between the experimental groups. Conclusions: It was concluded that the feed intake or water hardness did not change the pharmacokinetic profile of fluralaner in layer chickens. Therefore, fluralaner could be used before or after feeding with the varying water hardness in poultry industry.

• Korean journal of food and cookery science
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• v.33 no.3
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• pp.292-299
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• 2017

Purpose: The present study explored cookie making performance using Jeju magma seawater to elucidate the effects of minerals in water on quality of baked goods. Methods: Seven water samples were analyzed for their mineral content, pH and water hardness. Starch pasting properties of flour in water samples was analyzed using RVA, and cookie making performance using water samples was evaluated with the AACCI wire-cut cookie baking method. Quality of cookies was measured by weight loss during baking, cookie geometry, color, and firmness. Results: Hardness of water samples ranged from 0-4200, and mineral content was in the order of magma seawater > 100% ED mineral water > 50% ED mineral water > 10% ED mineral water > tap water > Samdasoo > distilled water. RVA results showed that water hardness exhibited significant relationships with pasting temperature (p<0.05, R=0.863), peak viscosity (p<0.001, R=0.944), final viscosity (p<0.05, R=0.861), and setback (p<0.05, R=0.782). Cookie baking results showed that cookie diameter increased in the order of magma seawater < 100% ED mineral water < 50% ED mineral water < 10% ED mineral water $\approx$ tap water < Samdasoo < distilled water. Conclusion: As mineral content in water increased, flour pasting temperature and viscosity increased, whereas cookie diameter decreased with color fading. However, cookies formulated with 50% ED mineral water showed similar cookie geometry and texture to those with tap water. Therefore, controlling the mineral content of water can be successfully applied to produce mineral-enriched cookies.