• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.315-324
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• 2002

The purpose of this in vitro study was to evaluate the efficiency of Er:YAG laser on calculus removal and the morphologic changes and hardness of the irradiated surface at different power settings. This experiment used human teeth which were extracted due to periodontal disease and had a band of calculus. Forty root slabs ($5{\times}5mm$) were made and divided into control group and irradiated groups. Experimental groups were as follows; Control group (root planing), Group1 (irradiated with laser at 30mJ), Group2 (irradiated with laser at 60mJ), Group3 (irradiated with laser at 100mJ). Twelve root slab embedded in resin block were used in each group. Er:YAG laser was applied under water irrigation with the tip held perpendicular to the root surface in contact mode. The treatment time was measured until the calculus was removed completely under naked eyes. The efficiency of calculus removal was evaluated by the time for removal. Morphological changes of laser irradiated site were observed under SEM and the surface hardness was measured using a VH tester. The results were as follows; 1. The efficiency of laser scaling was increased with increasing the energy level of irradiation(p<0.05). 2. The morphological changes such as carbonization, crater and scale-like defects in the irradiated root surface were frequently observed with increasing the energy level. 3. The surface hardness tended to increase at 60mJ and 100mJ irradiated groups than that of control group. From the results evaluting on the efficiency, morphological change and surface hardness, lower energy level was suggested for the clinical application of the Er:YAG laser in scaling.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.3
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• pp.137-141
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• 2007

The sugar content of persimmon fruits was decreased when food-waste compost was used. Dungsi was brighter with yellow color than that of control. The Gabjubaekmok was darker than that of control with red color. It was suggested that taste of astringent was reduced because total phenol and soluble tannin contents were reduced by that compost. The vitamin C content of persimmon fruits during storage was higher than that of control. Stability of persimmon fruits by that compost and usual compost was about the same at room temperature. At low temperature, hardness of persimmon fruits was maintained for 20days. Hardness and reducing sugar contents of persimmon fruits were increased by food-waste compost. The result was shown that there was no effect on composition of persimmon fruits by food-waste compost and maintaining hardness at room temperature, but at low temperature, the composition of persimmon fruits was changed.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.402-408
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• 2011

BACKGROUND: Effect of various light wavelength and plant defense molecules were evaluated on the hardness and the contents of free amino acid including ${\gamma}$-aminobutyric acid (GABA) in soybean sprouts. METHODS AND RESULTS: Germinating soybean seeds were treated with various single wavelength of light (380, 440, 470, and 660 nm) or without light at $25^{\circ}C$ for six days. Soybean seeds were also treated with stress-signaling molecule ethephon or $H_2O_2$ at the same time. Soybean sprouts treated with 470 nm substantially raised the hardness almost two times than the control. The free amino acid contents were higher in 470 nm and $H_2O_2$ treated soybean seeds than the control. Nutritionally beneficial GABA contents were increased by the treatments of 470 nm, 440 nm, ethephon, and $H_2O_2$. CONCLUSION: These results suggest that the hardness and the contents of amino acids can be regulated by stimuli, which stimuli could be composed of various wavelength and plant defense molecules. Especially, single wavelength 470 nm illumination has the effect of increasing GABA contents with increased hardness.

• The Korean Journal of Community Living Science
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• v.23 no.3
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• pp.233-243
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• 2012

This study was performed to determine the quality characteristics of Jeungpyun with added modified starch. The addition of modified starch did not change the pH level of the samples, but it did increase the volume. The b-value of Jeungpyun with 3% modified starch was significantly lower than that of the control group. The addition of 3% modified starch also significantly increased the hardness, adhesiveness, gumminess and chewiness of the experimental group over the control group. In the test of sensory characteristics, the cell size of Jeungpyun with 2 and 3% modified starch was larger than that of the control group. Cell uniformity of Jeungpyun with 2% modified starch was lower than that of the control group. The hardness of Jeungpyun with modified starch was significantly higher than that of the control group. In the test of taste preference, Jeungpyun with modified starch beat the control group substantially. The quality of Jeungpyun with 1 and 3% modified starch showed a higher overall score than that of the control group.

• The Korean Journal of Food And Nutrition
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• v.22 no.2
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• pp.185-191
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• 2009

This study investigated the effects of adding hard and soft wheat flour to Korean rice cakes(Karedduk) to retard retrogradation, by examining texture properties and descriptive sensory qualities after 2 and 24 hrs of storage at $5^{\circ}C$. The hard and soft wheat flour were combined with dry rice flour at levels of 0, 5, 10, and 20%. The texture properties, as analyzed by a Texture Analyzer, revealed that the springiness, cohesiveness, and adhesiveness of the rice cakes containing wheat flour were similar to those of the control, while chewiness, gumminess, and hardness were lower compared to the control. Also, in sensory analyses, hardness was significantly different in the rice cakes containing wheat flour compared to the control after 24 hrs of storage at $5^{\circ}C$. Overall, the instrumental texture properties were highly correlated with the sensory characteristics. These results suggest that adding hard and soft wheat flour to Korean rice cakes(Karedduk) is effective at retarding retrogradation.

• Preventive Nutrition and Food Science
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• v.4 no.4
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• pp.226-230
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• 1999

This study was done to determine how added vegetable oils affect the physical, chemical and microbial properties of experimental frozen desserts. There were no differences in the percentages of total fat and total solids in the seven frozen desserts. Freezing points did not differ among treatments. There were significant differences in viscosity among the frozen desserts containing up to 80% of vegetable oils. Oil substitution at 30% or higher significantly decreased viscosity when compared to the milk fat control. The hardness of frozen desserts decreased significantly with increasing addition of oils. Oil substitution at 20% or higher significantly decreased hardness. Substitution of canola and soybean oils for milk fat increased melting rate. Initiation of fluid release in the control was slower than in frozen products with added oils. The SPC values and coliform counts of all frozen products were not significantly changed. Cholesterol content decreased significantly in the products as the vegetable oil content was raised. Frozen desserts containing 10% or 60% of vegetable oils in the total fat contained 91.8%, 73.5% or 32.5%, respectively, of the cholesterol in the control.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.3
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• pp.77-81
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• 2017

Pulse electroplating of Ni-P alloy was studied to fulfill the material requirement to the advanced vertical probe tip in wafer probe card. The major concerns are for the electrical conductivity and yield strength. Plating parameters such as current density, duty cycle and solution components were examined to obtain the nanocrystal structure and proper percentage of phosphorus, leading to how to control the nanocrystal grain growth and precipitation of $Ni_3P$ after heat treatment. Among the parameters, the amount of phosphorus acid was the main factor affecting on the grain size and sheet resistance, and the amount of 0.1 gram was appropriate. Since hardness in Ni-P alloy is increased by as-plated nanocrystal structure plus precipitation of $Ni_3P$, the concentration of P less than 15 at% was better choice for the grain coarsening without minus in hardness value. The following heat treatment made grain growth and dispersion of precipitates adjustable to meet the target limit of resistance of $100m{\Omega}$ and hardness number of over 1000Hv. The Ni-P alloy will be a candidate for the substitute of the conventional probe tip material.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.106-114
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• 2014

For the purpose of development of polyurethane sealing material, polyurethane resins reinforced with CuO were prepared from polyol and MOAC(4,4'-Methylenebis(2-chlorobenzeneamine)). And the effects of compositions on the mechanical properties of the reinforced polyurethane resin were experimentally examined. The polyurethane resin got to be thermally decomposed at $260^{\circ}C$ and completely carbonized around $500^{\circ}C$. Tensile strength, elongation and hardness of the polyurethane resin increased with the content of MOCA. CuO was uniformly dispersed in the polyurethane resin by 1 minute's ultrasonic radiation. Tensile strength, elongation and hardness of the polyurethane resin reinforced with CuO increased with the content of CuO. Tensile strength and hardness of the reinforced polyurethane resin increased with particle size of the CuO, but elongation decreased. CuO showed higher tensile strength and hardness than any other additives, and lowest elongation.

• Journal of Technologic Dentistry
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• v.27 no.1
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• pp.65-71
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• 2005

Experimental Ti-13%Zr and Ti-13%Zr-5%Cu alloys were made in an argon-arc melting furnace. The grade 2 CP Ti was used to control. The alloys were cast into phosphate bonded $SiO_2$ investment molds using an argon-arc casting machine, and The hardness and microstructures of the castings were investigated in order to reveal their possible use for new dental casting materials and to collect useful data for alloy design. The hardness of the Ti-13%Zr-5%Cu alloy(379Hv) became higher than that of Ti-13%Zr(317Hv) alloy, and the hardness of this alloys became higher than that of CP Ti(247Hv). Increasing in the hardness of the Ti-13%Zr-5%Cu alloy was considered to be solid solution hardening as the Ti-Zr system shows a completely solid solution for both high temperature $\beta$phase and low temperature $\alpha$ phase and also the inclusion of the eutectoid structure($\alpha Ti+Ti_{2}Cu$). No martensitic structures are observed in the specimen made of CP Ti, but Ti-13%Zr and Ti-13%Zr-5%Cu alloys show a kind of martensitic structure. Ti-13%Zr-5%Cu shows the finest microstructure. From these results, it was concluded that new alloys for dental casting materials should be designed as Ti-Zr-Cu based alloys.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.6
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• pp.336-344
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• 2001

For the establishment of the world wide unified scales of the Rockwell hardness test with conical indenters, round robin test was carried from 1998 to 2000. The pilot laboratory was MPA-NRW and 12 laboratories from 11 countries participated In this RRT. Rockwell hardness of 74 specially prepared blocks was measured for the scales of C, A, D, 45N, 30N, and 15N and the results were compared. It was found that the geometric form of indenter affects on the results very significantly and standardization in the measurement and evaluation of indenter should be established in short time for the reliable hardness measurement. KRISS showed good results in general for all of the ranges except 15N scale which showed relatively large difference compare to the mean value. It was concluded that poor control in loading velocity of the dash pot was the major reason.