• Journal of the Korean GEO-environmental Society
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• v.24 no.9
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• pp.25-32
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• 2023

The Korean Industrial Standards (KS F) have a various regulations for measuring the weight of dried soil and rock. However, if the dried weight is measured in air after drying at 110±5℃ or 105±5℃, a weight singularity occurs, in which the weight decreases and then increases as the measurement time continues. In this study, basaltic rock from Ulleung Island was oven dried at 40 to 110℃. The weight was measured on an electronic scale with a sensitivity of 0.0001g (0.1mg) to find weight singularities. A method to easily determine the dry weight using the weight singularities was presented. As a result of analyses of the singularity of rock specimen according to temperature, the singularities were appeared in the temperature range of 40 to 110℃, and the weight of the singularity was smaller as the heating temperature increased. In particular, the weight singularity duration appeared, and the duration of the singularity was shorter as the heating temperature increased. The results of the convection measurement experiment showed that the cause of the singularity is the convection phenomenon caused by the contact of the heated rock with the air. The weight decrease of oven dried rock occurs when the effect of convection is dominant over the effect of air moisture absorption. Conversely, the weight increase of rock occurs when the effect of air moisture absorption is dominant over the effect of convection.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.19-28
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• 2011

This study developed a solar radiation reflection pavement, so called a cool pavement, to lessen the urban heat island effect by coating a pavement surface with acrylic resins mixed with light-colored pigments. From a laboratory test, simulating solar heating process in pavements, the cool pavement reduced more than $12^{\circ}C$ of pavement temperature at $60^{\circ}C$ compared to a control porous pavement. With the increase of the mixing ratio of the pigments to acrylic resins, the temperature reduction effect increased, but its workability became worse due to higher viscosity. As a result, an appropriate mixing ratio was determined as 15%. The cool pavement had better durability than the control pavement: One quarter of Catabro loss and twofold dynamic stability. Its adhesion was also higher enough not to be debonded under traffic loading. In-situ noise and friction tests conducted in two field sites showed that the cool pavement reduced its noise level by 3.7dB in average and increased its friction level by 30% compared to the control pavement. The permeability of the cool pavement was little lower than the control pavement, but higher enough to satisfy the minimum requirement for porous pavements.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1610-1615
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• 2008

Natto is a Japanese traditional soybean product fermented by Bacillus natto. The effects of dried fermented soybean (natto) supplement on egg production and egg qualities of layer chickens was studied with regard to the effective use of various waste foods in Japan. Dried natto, prepared by heating at $60^{\circ}C$, was added to a basic diet at a level of up to 3%. Forty 166-wk-old layer chickens (Rhode Island Red) were randomly divided into 4 groups and five layer chickens were used in each group with two replicates. Layer chickens in group 1 were fed a basic diet as the control. The remaining 3 groups were fed the basic diet supplemented with dried natto at levels of 1, 2, and 3% (w/w), respectively. The result did not show improvements in egg production or feed conversion ratio of layer chickens even when 3% dried natto was added to the control diet. The egg qualities including egg weight, eggshell strength and thickness, yolk color, yolk weight, albumen height, and Haugh unit were also not improved. However, the feeding of dried natto changed the cholesterol content in the egg yolk. The supplementation of dried natto showed the tendency to decrease the yolk cholesterol after 12-wk of feeding compared to the control diet though it did not change plasma cholesterol levels in the blood. On the other hand, yolk cholesterol decreased significantly after 12-wk of feeding 3% dried natto (p<0.05).

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.81-90
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• 2017

This study was conducted to investigate the thermal environment status of nursery rooms in workplace daycare centers in Jeju and propose measures to improve their indoor physical thermal environment. For this purpose, measurements were performed in the winter indoor physical environment of 51 nursery rooms in 11 workplace daycare centers and a psychological evaluation survey on the thermal environment of nursery rooms was conducted for 70 nursery teachers. The investigation was carried out over 11 days in January 2017. The results are as follow. The average indoor temperature of the nursery rooms was $21.3^{\circ}C$($18.7-23.8^{\circ}C$) and the indoor temperatures of 47 nursery rooms (92.9%) were higher than the environmental hygiene management standard for domestic school facilities ($18-20^{\circ}C$). The average relative humidity was 33.9% (16.4-56.0%), and 37 nursery rooms (86.3%) showed a lower average relative humidity than the standard (40-70%). The average absolute humidity was $9.1g/m^3$ ($4.7-13.6g/m^3$), which was lower than the standard for preventing influenza ($10g/m^3$). When the indoor temperature and humidity of the nursery rooms were compared with international standards, it was found that 85% or more of the 51 nursery rooms maintained appropriate indoor temperatures, but 40-50% of the nursery rooms maintained a low humidity condition. Therefore, they need to pay attention to maintaining the appropriate humidity of the nursery room to keep the children healthy. The average indoor temperature of the nursery rooms showed a weak negative correlation with the average relative humidity. The indoor temperature had a significant effect on the relative humidity: a higher indoor temperature resulted in lower relative humidity. Regarding the fluctuations in the average indoor temperature of the nursery rooms during the day, in daycare centers that used floor heating, the indoor temperature gradually increased form the morning to the afternoon and tended to decrease during lunch time and the morning and afternoon snack times, due to ventilation. The daycare centers that used both floor heating and ceiling-type air conditioners showed a higher indoor temperature and greater fluctuations in temperature compared to the daycare centers that used floor heating only. In the survey results, the average value of the whole body thermal sensation was 3.0 (neutral): 32 respondents (62.7%) answered, "Neutral", Which was the largest number, followed by 21 respondents (30%) who answered, "Slightly hot" and 17 respondents (24.2%) who answered, "Slightly cold." Twenty-nine respondents answered, "Slightly dry," which was the largest number, followed by 28 respondents (54.9%) who answered, "Neutral" and 10 respondents (19.6%) who answered, "Dry." The total number of respondents who answered, "Slightly dry" or "Dry" was large at 39 (56.4%), which suggests the need for indoor environment management to prevent a low-humidity environment. To summarize the above results about the thermal environment of nursery rooms, as the indoor temperature increased, the relative humidity decreased. This suggests the effect of room temperature on the indoor relative humidity; however, frequent ventilations also greatly decrease the relative humidity. Therefore, the ventilation method and the usage of air conditioning systems need to be re-examined.