• 한국가스학회:학술대회논문집
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• 1997.09a
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• pp.229-235
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• 1997

A low power (300 mW) catalytic bead combustible gas sensor is developed and utilized with a computer controlled sampling system for measuring heat content of natural gas. The heat content of gas is proportional to the change in the energy required to exposure to the sample of combustible gas. The heat content of natural gas samples ranging 36.30 - 39.88 MJ/$m^3$ is measured in the range of approximately $1\%$ error, which is comparable to its nominal heat content. Each gas has a slightly different curve of sensitivity vs. sensor temperature. Thus there Is no temperature at which all sensitivities are equal. In calibration process the choice of a optimum operating temperature is an important factor that influences the overall performance of the measurement system.

• Journal of Korea Foundry Society
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• v.4 no.1
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• pp.12-20
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• 1984

In order to investigate the effect of size of sand grains, bentonite content and moisture on mixing power, standard mixing power, permeability, green compressive strength and green mold hardness were measured with mixing time, and also coated layer of mixed sand with time was observed by optical microscope and scanning electron microscope. From this experiment, the results were summarized as follows. 1. Mixing power increased as size of sand grains decreased. 2. Mixing power increased gradually as bentonite content increased and in particular, increased rapidly in 7-10% bentonite. 3. Mixing power increased as moisture content decreased. 4. The mixing time required to get the optimum mixing power decreased as moisture content and grain size increased, but increased as bentonite content increased.

• Macromolecular Research
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• v.16 no.7
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• pp.596-603
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• 2008

To improve the mechanical properties, dimensional stability and blood compatibility, the biomedical material $Pellethene^{(R)}$ was blended with multiblock polyurethane (MPU) containing phospopholipid/long alkyl chain (C-18) at the various MPU contents and crosslinked using dicumyl peroxide as a crosslinking agent. The maximum MPU content for stable $Pellethene^{(R)}$/MPU blended films was approximately 30 wt%. The optimum crosslinking agent content and crosslinking time with respect to the mechanical properties were 4 wt% and 3 h, respectively. The mechanical properties (tensile strength and elongation at break) and water absorption of the crosslinked blend film increased with increasing MPU content. The test of platelet adhesion on the surfaces of the crosslinked blend film showed a decrease in the level of platelet adhesion from 70% to 6% with increasing MPU content from 0 to 30 wt%. These results suggest that the crosslinked $Pellethene^{(R)}$/MPU-30 (MPU content: 30 wt%) sample has strong potential as a novel material for blood compatible material applications.

• Elastomers and Composites
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• v.53 no.3
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• pp.168-174
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• 2018

Natural rubber (NR) and bromo-isobutylene-isoprene rubber (BIIR) were compounded with other formulation chemicals through polymer blending via a mechanical mixing method. After rubber vulcanization by hot-press compression molding, the cure characteristics, mechanical properties, and ozone resistance of the NR/BIIR blends were measured. As the BIIR content increased, the maximum torque of the blends decreased, while the optimum cure time and scorch time tended to increase. Furthermore, the hardness of the blends increased with increasing BIIR content, reaching the maximum value at 75 wt% BIIR, and decreased with a further increase in the BIIR loading. The tensile strength and elongation at break decreased with an increase in the BIIR content, reaching the minimum value at 75 wt% BIIR, and increased with a further increase in the BIIR content. In the ozone resistance test, cracks were not generated when the BIIR content was more than 75 wt%.

• Journal of Apiculture
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• v.32 no.4
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• pp.327-332
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• 2017

In this study, we studied the changes in antioxidant activity of Actinidia arguta fruit of Autumn Sense cultivar during fruit ripening. The aim of this investigation was to find the knowledge of the changes of physiochemicals associated with fruit quality, antioxidant properties (free-radical scavenging activity and reducing power), total phenolics and vitamin C during fruit ripening. The highest free-radical scavenging activity (at $100{\mu}g/ml$) and reducing power (at $100{\mu}g/ml$) in A. arguta fruit were 78.57% and 0.22, respectively. Total phenolic content and vitamin C content in fruit of 10 days after fruit set were $639.48{\mu}g/g$ and $1052.2{\mu}g/g$, respectively. In general, the antioxidant activity and the related parameters, including total phenolic content and vitamin C content decreased during fruit ripening. These results improve knowledge of the effect of ripening on the antioxidant activity and related compounds contents that could help to establish the optimum A. arguta fruit harvest data for various usages.

• Korean Journal of Poultry Science
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• v.12 no.1
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• pp.39-44
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• 1985

These studies were conducted to compare the nutritive values and optimum prices of eggs among 6 groups of different egg Weight. With the total of 100 eggs of each weight group, after the weight percentage of egg yolk, albumen and shell in the whole egg were investigated, protein and fat contents of e99 yolk and albumen were analyzed. and then protein and fat contents in the whole eggs were calculated. Finally, the optimum prices of eggs in relation to the egg weight were studied on the basis of egg weight, protein content and protein plus fat contents of eggs, respectively. The results obtained are summarized as follows; 1. As the egg weight (X, g/10 eggs) increased, egg yolk (Y$_1$, %) and shell(Y$_2$, %) percentages tended to decrease, but egg albumen(Y$_3$, %) percentage increased lineally; Y$_1$=44.34-0.02X, Y$_2$=15.358-0.006 X, and Y$_3$=40.136＋0.026 X. 2. There were no significant differences in protein and fat contents of eggs among 6 different groups of egg weight. 3. Protein (Y$_1$, %), fat (Y$_2$, %) and protein plus fat (Y$_3$, %) contents in the whole eggs declined progressively as the egg weight (X, g/10 eggs) increased ; Y$_1$=11.943-0.00032X, Y$_2$=13.996-0.00614X, and Y$_3$=25.939-0.00646X. 4. Similar results were obtained whether the optimum prices of eggs were estimated on the basis of egg weight or protein content of eggs, and they were higher in the large size eggs and lower in the small size eggs than the optimum prices of eggs estimated on the basis of protein plus fat content of eggs.

• Resources Recycling
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• v.22 no.1
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• pp.20-28
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• 2013

Recently, as the registration of vehicles increases, the utilization of the waste tires is emerging as environmental issues. Crumb rubber reproduced by scrap tires has been reused up to 25% in the construction field. The purpose of this paper is to investigate the mechanical properties of sulfur-rubber concrete (SRC) and to suggest the optimum mix design in terms of the compressive strength. Specimens were prepared with various mixing parameters: amount of sulfur, rubber, and micro-fillers. Two casting processes were also mentioned; dry process and wet process. The results mainly showed that the compressive strength of SRC decreased with an increment of rubber content. However, adding micro-filler and adjusting sulfur contents could improve the compressive strength of SRC. Optimum values of sulfur and rubber content were selected by workability and compressive strength of SRC. SRC can be applied to road constructions where high strength of concrete is not concerned, to wall panels that require low unit weight, to construction of median in highways to resist high impact load, and in sound barriers to absorb sound waves.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.644-649
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• 1996

The purpose of this study was to investigate the relationship between physicochemical properties and optimum amount of added water for cooking in the preparation of Korean cooked rice (bab). Seven different kinds of rice samples were tested for their chemical and physical properties in relation to the eating quality after cooking with various amounts of water added. The amylose content and water content of rice did not show significant correlation with the amount of added water for optimum cooking. The width of rice kernel, expansion ratio, amylogram maximum viscosity showed significant correlation with the optimum ratio of added water for cooking.

• Journal of Ginseng Research
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• v.6 no.1
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• pp.38-45
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• 1982

To determine the optimum light intensity for growth of ginseng plants, change of temperature, moisture content in son, occurrence alternaria blight, defoliation rate, chlorophyll contents, and growth of shoots and roots were investigated under different light intensity such as 5%, 10%, 20% and 30% light transmittance rare(L.T.R.). The results obtained were as follows. 1. Maximum temperature under the shading was increased as the increase of light intensity, whereas soil moisture content decreased 2. As the increase of light intensity, stem and Peduncle length, leaf area, and chlorophyll contents decreased significantly but length and width of the leaf was not significant, while stem diameter, special leaf weight and chlorophyll a/chl. b ratio increased 3. Stem color was shown dark purp!e as the increase of light intensity. 4. Photosynthesis during the day was highest at 9 A.M. and decreased as time passed in all plots. The means of photouynthesis during the day showed in the order of 20%, 10%, 30%, 5% L.T.R., and optimum light intensity for highest photosxthesis was 18.4% L.T.R. by theoritical equation. 5. It was showed a tendency that alternaria leaf blight of ginseng plants was increased as the increase of light intensity. 6. Defoliation rate of ginseng plants was increased as the increase of light intensity, especially all plants were defoliated by late June without shading. 7. Yield percentage of the rear line was increased as the increase of light intensity. Root weight per plant showed in the order of 20%, 10%, 30%, 5% L.T.R., and optimum light intensity for the best yield was 18.5% L.T.R. by theeritical equation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.159-162
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• 1999

This study was carried out to determine the optimum harvest date of unshelled immature peanuts and dried kernels from 60 to 120 days after flowering. Fresh pod yield of spanish-type variety, 'Shaedl-tangkong(SD)' reached a peak of 9,140kg/ ha at 70 (days after flowering(Aug. 13) while that of virginia-type variety, 'Daepoongtangkong(DP)' reached a peak of 8,820kg/ha at 90 days(Sept. 11) after flowering. SD and DP showed maximum fresh kernel yield of 6,090 and 6,470kg/ha at 90 days after flowering (Sept. 11), respectively, while dry kernel yield reached a peak of 3,300 and 3,720kg/ha at 110 days(Oct. 1), respectively. Oil content of SD and DP were the highest at 90 days and 100 days after flowering, respectively and the oil content of two varieties increased rapidly from 60 to 90 days. Tannin content of the seed hull of SD increased continuously until 110 days after flowering while that of DP maximized at 100 days. The tannin content of the two varieties increased rapidly from 60 to 100 days. Total sugar of SD and DP showed highest content at 60 days and 70 days after flowering, respectively and suger content decreased very rapidly until 80 days and after that sugar content kept nearly constant. Oil, tannin and total sugar content of spanish-type SD were higher than those of virginia-type DP.