• The Korean Journal of Food And Nutrition
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• v.19 no.4
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• pp.473-481
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• 2006

This study was carried out to investigate the properties of cucumber kimchi prepared with different minor ingredients(potato, puchu). Acidity, pH, color value, hardness, and lactic acid bacteria were measured under the condition of $10^{\circ}C$ for 25 days. Five conditions of making cucumber kimchi included: cucumber kimchi with puchu 300g(treatment 1, control), cucumber kimchi with potato 90g, puchu 210 g(treatment 2, 5-1), cucumber kimchi with potato 150g, puchu 150 g(treatment 3, S-2), cucumber kimchi with potato 210g, puchu 90 g(treatment 4, S-3), cucumber kimchi with potato 270g, puchu 30g(treatment 5, S-4). Hardness of cucumber kimchi appeared higher values as the potatoe's volume increased(S-1, S-2, S-3, S-4), during all fermentation days. The results showed very significant values in pH(p<0.001), acidity(p<0.001), 'L' of lightness(p<0.05), hardness(p<0.001), lactic acid bacteria(p<0.001) according to fermentation. And the results showed very significant values in 'a' of redness(p<0.01), hardness(p<0.001) according to cucumber kimchi samples. These results showed that fermentation patterns of cucumber kimchi were influenced by the different minor ingredients used.

• Journal of the Korean Society for Heat Treatment
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• v.9 no.3
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• pp.177-186
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• 1996

Surface alloying of Ti alloy by $CO_2$ laser is able to produce few hundred micrometers thick TiN or TiC surface-alloyed layer with high hardness on the substrate by injecting reaction gas($N_2$ or $CH_4$). Laser surface alloying by means of process control is in many applications essential in order to obtain predictable hardening layer. This research has been investigated the effect of such parameters on TiN and TiC gas alloying of Ti-6Al-4V alloy by $CO_2$ laser. The maximum surface hardness of TiN layer was obtained 1750Hv on the conditions of 0.8kW laser power, 0.8m/min scanning speed and 100% $N_2$ atmosphere. However, the maximum hardness of TiC formation layer after laser treatment was about 630Hv. As scanning speed was increased, the hardness and depth of these layers were decreased at constant laser power.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.4
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• pp.191-196
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• 2003

For improvement of the wear performance of Ti alloy, vacuum-carburizing technique was tried for the first time using propane atmosphere. During the low pressure carburizing carbide was formed at the surface and carbon transfer was occurred from the carbide to the matrix. It was found that: (i) surface hardness increased with the reduction of operating pressure and time; (ii) optimum hardness distribution could be obtained with the proper choice of temperature and carbon flux control; and, (iii) case depth was largely influenced not by time but by temperature. The two steps process was recommended for obtaining thick case depth and high surface hardness of Ti alloy. For the low oxygen partial pressure, it was necessary to introduce additional CO gas to the atmosphere.Grain boundary oxidation and non-uniformity could be prevented.

• Journal of the Korean Society for Heat Treatment
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• v.31 no.2
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• pp.56-62
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• 2018

Many researchers have studied on the precipitation control after solution treatment to improve the damping capacity without decreasing the strength. However, studies on the damping capacity and microstructure changes after deformation in the solid solution strengthening alloys were inadequate, such as the Al-Zn series magnesium alloys. Therefore, in order to investigate the effect of annealing condition on microstructure change and damping a capacity of AZ61 magnesium alloy. In this study, it was confirmed that the microstructure changes affect the damping capacity and hardness when annealed AZ61 alloy. AZ61 magnesium alloy was rolled at $400^{\circ}C$ with rolling reduction of 30%. These specimens were annealed at $350^{\circ}C$ to $450^{\circ}C$ for 30-180 minutes. After annealing, microstructure was observed by using optical microscopy, and damping capacity was measured by using internal friction measurement machine. Hardness was measured by Vickers hardness tester under a condition of 0.3 N. In this study, static recrystallization was observed regardless of the annealing conditions. In addition, uniform equiaxed grain structure was developed by annealing treatment. Hardness is decreased with increasing grain size. This is associated with Hall-Petch equation and static recrystallization. In case of damping capacity, bigger grain size show the larger damping capacity.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.505-518
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• 1997

The objective of this investigation was to compare the effects of water storage on the aspect of hardness and diametral tensile strengths of four hybrid glass ionomer cements(two compomers and two resin-reinforced glass ionomers) with a resin composite material. One composite resin(Degufill Ultra), two compomers(Dyract, Compoglass Cavifil), and two resin-reinforced glass ionomers(Fuji Duet, Vitremer) were used in this study. Cylindrical specimens were prepared and stored at $36{\pm}1^{\circ}C$ in distilled water for 10 minutes after set, and then tested on an Instron testing machine(No.4467) at 1.0 mm/min displacement rate. Vicker's hardness and diametral tensile strengths as time elapsed were measured after aging in water for 10 minutes, 1 hour, 3 hours, 1 day, 3 days, 5 days and 7 days at $36{\pm}1^{\circ}C$. During the test of diametral tensile strength, stress-strain curves were obtained, from which the compressive modulus were calculated and compared. The structure of four set glass ionomer cement mass was observed on SEM(Hitachi, S-2300) after being etched with 9.6% hydrofluoric acid for 1 minute. The results were as follows; 1. The hardness of the experimental group(compomer and the resin reinforced glass ionomer cement) did not exceed the value of control group(Degufill Ultra). 2. Vicker's hardness of the Fuji Duet tended to increase succeedingly, Dyract was decreased after 3 hours in water, and Vitremer was the lowest. 3. The control group(Degufill Ultra) presented progressively on increased diametral tensile strength with time, Fuji Duet were decreased after 3 days, Compoglass Cavifil and Vitremer were decreased after 5 days in water storage. 4. Compressive modulus of the control group(Degufill Ultra) and Dyract were increased sharply timely, Fuji Duet and Vitremer were increased smoothly by lapse of time in water. Fuji Duet were stronger than Vitremer. On the other hand, Vitremer exhibited the lowest toughness. 5. The microstructure of compomer was similar with that of the composite resin(Degufill Ultra), and the fillers in resin-reinforced glass ionomer cements were noticed. It can be concluded that mechanical properties of hybrid glass ionomer cements is weaker than composite resin, and that the compomers or the resin-reinforced glass ionomers can not substitute the composite resins. A plenty of considerations should be done on the application of them to the area under the loading and high wear has a little adverse effect on the mechanical properties on the water storage for 7 days. The further research should be needed to confirm the advantage of the compomer.

• Korean Journal of Human Ecology
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• v.9 no.4
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• pp.75-81
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• 2006

In this study on the recipe for Yakgwa in Jeonbuk province, a survey of the ingredients, the quantity and the recipe for Yakgwa were conducted by an interview with the notable maker of it in 9 regions ; Jeonju, Imshil, Jangsu, Jeongup, Namwon(Samaemyeon & Dukgwamyeon), Wanju, Gochang, Iksan, away from each other. The hardness testing and the sensory evaluation of Yakgwa were carried out to compare with the control group and Jeonbuk Yakgwa. The results of this study are as follows ; 1. Common ingredients of Yakgwa examined in 9 regions were flour, sesame oil or soybean oil, honey or sugar, ginger juice, alcoholic drinks and etc. The quantity of oil (sesame or soybean) per kilogram of flour was as follows between one-half and one cup of oil, between one and three cups of honey or sugar, between one-half and one cup of ginger juice and between one-half and one cup of alcoholic drinks. Making of Yakgwa in Jeonju and Imshil area, knead flour with the liquid ingredients which are mixed together before. In other areas, after sifting the mixed flour with sesame oil, and then knead the remaining with the sifted. 2. The result of the hardness testing of Yakgwa was that it is higher in this order, Iksan, Imshil, the control group, Jeongup, Jeonju. With while the difference of syrup used in each of them, the result of hardness testing in the same order shows that the component of Yakgwa has more great effect on the hardness than a kind of syrup on which the result by using syrup before&after cooking. And in the sensory evaluation, the surface color of Iksan Yakgwa was the most bright of all, and the shininess was of Imshil and the control group, the cracked level, the softness, the sweet taste and the oily taste of Jeonju Yakgwa was better than other Also, the overall preference, though less meaningful, was same result.

• Journal of dental hygiene science
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• v.22 no.1
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• pp.20-29
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• 2022

Background: The purpose of this study is to investigate the effect of liquefied digestive medicines on the composite resin surface. Methods: Three types of liquefied digestive medicines (Gashwalmyeongsu, Wicheongsu, and Saengrokcheon) were selected as experimental groups, Samdasoo and Chamisul as negative controls, and Trevi as positive controls were selected to measure pH and titratable acidity. The samples filled with resin at acrylic were made total 300, 50 per group. To evaluate the erosion risk of the composite resin, the specimens were immersed in a liquefied medicine for 1, 3, 5, 15, and 30 minutes, and then the surface microhardness was measured using the Vickers Hardness Number, and the surface change was observed with scanning electron microscope (SEM). Results: The average pH of the three liquefied medicine was 3.75±0.30, the Saengrokcheon was the lowest at 3.45±0.01, and the Trevi was 4.66 and Samdasoo and Chamisul were 7.40 and 8.58, respectively. The amount of NaOH reaching pH 5.5 and 7.0 was the lowest in the order of Trevi, Gashwalmyeongsu, Wicheongsu, and Saengrokcheon. The largest surface hardness reduction value was shown in Gashwalmyeongsu (-11.85±3.73), followed by Saengrokcheon (-9.79±3.11) and Wicheongsu (-8.28±2.83), and Samdasoo (-0.84±1.56) and Chamisul (-6.24±0.42) had relatively low surface hardness reduction values. However, Trevi (-16.67±5.41), a positive control group containing carbonic acid, showed a higher decrease in surface hardness than the experimental group. As a result of observation with SEM, experimental group and positive control group, showed rough surfaces and irregular cracks, and negative control groups showed smooth patterns similar to before immersion. Conclusion: The liquefied digestive medicine with low pH could weaken the composite resin surface, and the carbonic acid component could more effect on the physical properties of the composite resin than pH.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2005.06a
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• pp.71-83
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• 2005

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.258-266
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• 2011

Scale induced by hardness materials in water must be controled because of it can be result in remarkable damages of pipeline as well as water quality deterioration. Especially hot water system is one of scale management required facility as scale formation can be accelerated by temperature. The scale control performance of frequency driver (FD) was tested instead of existing methods such as chemical, physical and electromagnetic methods which needs chemicals and electric power. Three kinds of pipe coupons were submerged in test water with 500 mg/L of hardness for 33 days and XRD and SEM were analysed for comparing scale formation characteristics of these coupons. Calcite ($CaCO_3$) which came from hardness of water was formed on only cast iron pipe coupon and this coupon showed higher corrosion rate than copper and stainless steel pipe coupon. Hot water circulating system connected cast iron pipe with and without FD was operated with 300 mg/L of hardness water at $50^{\circ}C$ for monitoring of scale formation and water quality with and without FD. XRD showed that FD leaded to magnetite ($Fe_3O_4$) scale which is good scale for preventing corrosion than calcite and SEM image also indicated the scale control effect of FD. Scales of 16% on pipe joint, 14% on pipe length, and 42% on heat exchanger decreased with FD comparing scales of those parts without FD. From the results of water quality, FD reduced crystallization of hardness material without chemical reaction in water and it can indicate that FD is safe and proenvironmental technology for scale reduction.

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.13 no.1
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• pp.1-27
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• 2002

The present study was designed to examine the effects of different homogenization pressure, homogenization temperature and $\beta$-cyclodextrin concentration on cholesterol decrease rate of Cheddar cheese, and to optimize the factors of cheese manufacture Process. Il. The hardness(control 5.46kg/$cm^2$), gumminess(control 5.24kg), chewiness(control 4.87kg/cm) reduced to 2.03kg/$cm^2$, 2.18kg, 2.24kg/cm, respectively. In the result of sensory analysis, treatment of homogenization for cholesterol removed Cheddar cheese improved appearance and flavor, however texture fell. In addition, the resent result of the study indicated that about 75.27% of cholesterol in Cheddar cheese could be removed, and the possibility of development of cholesterol decreased Cheddar cheese was observed.