• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.134-135
• /
• 2016

This study aims to compare relative moisture content and gravity moisture content in calculating the rational percentage of moisture content. High-strength concrete, which is made of blast-furnace slag and silica fume, was used as the compound for this study, and the specimens were made into a saturated condition through the vacuum suction. According to the results of this study, all specimens were completely dried when they were under the temperature of 105℃ for more than 31 days. They were fully saturated after 72 hours through vacuum suction. In addition, relative moisture content responded more sensitively to moisture content than gravity moisture content did, so it can be concluded that relative moisture content is better in calculating the rational percentage of moisture content.

• Journal of Ecology and Environment
• /
• v.33 no.1
• /
• pp.47-57
• /
• 2010

To understand day-to-day fluctuations in soil moisture content in Seoul, I simulated daily soil moisture content from 1908 to 2009 using long-term climatic precipitation and temperature data collected at the Surface Synoptic Meteorological Station in Seoul for the last 98 years with a hydrological simulation model, BROOK. The output data set from the BROOK model allowed me to examine day-to-day fluctuations and the severity and duration of droughts in the Seoul area. Although the soil moisture content is highly dependent on the occurrence of precipitation, the pattern of changes in daily soil moisture content was clearly quite different from that of precipitation. Generally, there were several phases in the dynamics of daily soil moisture content. The period from mid-May to late June can be categorized as the initial period of decreasing soil moisture content. With the initiation of the monsoon season in late June, soil moisture content sharply increases until mid-July. From the termination of the rainy season in mid-July, daily soil moisture content decreases again. Highly stochastic events of typhoons from late June to October bring large amount of rain to the Korean peninsula, culminating in late August, and increase the soil moisture content again from late August to early September. From early September until early October, another sharp decrease in soil moisture content was observed. The period from early October to mid-May of the next year can be categorized as a recharging period when soil moisture content shows an increasing trend. It is interesting to note that no statistically significant increase in mean annual soil moisture content in Seoul, Korea was observed over the last 98 years. By simulating daily soil moisture content, I was also able to reconstruct drought phenomena to understand the severity and duration of droughts in Seoul area. During the period from 1908 to 2009, droughts in the years 1913, 1979, 1939, and 2006 were categorized as 'severe' and those in 1988 and 1982 were categorized as 'extreme'. This information provides ecologists with further potential to interpret natural phenomenon, including tree growth and the decline of tree species in Korea.

• The Korean Journal of Ecology
• /
• v.5 no.2_3
• /
• pp.123-131
• /
• 1982

The growth and the resistance of Amorpha fructicosa L. under water control was experimented in frames out of doors. The plant grew in a wagner's pot under water control. The soil moisture content was controlled at 5%, 10%, 15% and 20%. The growth of leaf, stem and root in the groups of 5% and 10% soil moisture content were different from values in the groups of 15% and 20%. The T/R ratio in the groups of 5% and 10% soil moisture content were different from the ratio in the groups of 15% and 20% soil moisture content. The T/R ratio of former was lower than the latter, but the C/F ratio of the former was higher than the latter. RGR and NAR of Amorpha fructicosa decreased in 5% and 10% soil moisture content but increased in 15% and 20% soil moisture content during growing period. The maximum values of RGR and NAR were respectively 0.089 and 0.080 at 20% soil moisture content. The highest value of LAR was 1.560 at 5% soil moisture content. RGR and NAR were comparatively affected by soil moisture content.

• Advances in concrete construction
• /
• v.13 no.6
• /
• pp.423-431
• /
• 2022

Although the influence of moisture content on the mechanical properties of concrete has been studied for a long time, research related to its influence on the damping and energy dissipation property of concrete structure is still very limited. In this paper, the relationship between damping property and moisture content of concrete using cyclic uniaxial compression is firstly presented, and the mechanism of the influence of moisture content on concrete damping and energy dissipation capacity is analyzed. Based on the experimental research, moisture-related damping and energy dissipation model is proposed. Results show that the dissipated energy of concrete and loss factor increase as the moisture content increasing. The energy dissipation coefficient reflecting the influence of stress level of concrete under cyclic load, decreases first and then increases as the moisture content increasing. The mechanism of moisture-related energy dissipation behavior can be divided into the reactive force of water, the development of the internal micro cracks and the pore water pressure. Finally, the proposed moisture-related damping and energy dissipation model are verified.

• Journal of Biosystems Engineering
• /
• v.27 no.1
• /
• pp.51-58
• /
• 2002

The goal of this research was to an optimum conditions for the brown rice conditioning from data of milling characteristics after conditioning of the brown rice. The range of the initial moisture content of the sample was 13%, 14%, and 15%, the range of the increment of the moisture content was 0.4% and 0.8% with respect to the initial moisture content, and a ripe time after conditioning was eight hours. The results obtained from this research can be summarized as fellows. 1 The crack ratio after conditioning the brown rice with the initial moisture content was increased as the initial moisture content decreased and increment of the moisture content increased. The crack ratio of the milled rice was increased than that of the non-conditioned brown rice and decreased with the conditioned brown rice with the increment of the moisture content of 0.4% and 0.5%. 2. The broken rice ratio after conditioning the brown rice with the initial moisture content was a little higher than that of the non-conditioned brawn rice. The broken ratio of the conditioned brown rice with the increment of the moisture content of 0.4% was increased around 0.2∼0.4% with respect to the non-conditioned brown riced and the broken ratio of the brown rice was high with increased amount of water sprayed during conditioning process. 3. The moisture content of the milled rice after conditioning the brown rice with the initial moisture content increased around 0.3∼0.8% with respect to the non-conditioned milled rice. 4. The electric energy consumption on milling process with the conditioned brown rice by the initial moisture content was decreased 3.4∼39.1% with respect to the non-conditioned brown rice.

• Journal of the Korean Wood Science and Technology
• /
• v.37 no.5
• /
• pp.459-464
• /
• 2009

This study was conducted to find the relationship between the moisture content and basic density of green lumber and the final moisture content of kiln dried lumber. The possibility of using a ultrasonic nondestructive testing technology was investigated. Four matched 2-foot long boards were kiln-dried for 12, 24, 36 and 48 hours. Twenty three slices were cut to examine the distribution of moisture content along the length. It was revealed that the green weight was a better estimator of the final moisture content of the kiln-dried board than the green moisture content. The standard deviations of the moisture contents of the slices were not correlated with the final moisture contents of the kiln-dried boards. The two ultrasonic devices used for this study were apparently good tools for NDT.

• Journal of Biosystems Engineering
• /
• v.35 no.3
• /
• pp.175-181
• /
• 2010

This study compared moisture content measured by moisture meter of microwave resistance type(MMMRT) and standard moisture content of paddy, and developed the correction equation using linear and curvilinear regression analysis, and to explore its significance test. The correction factor according to the range of moisture content was developed to improve the measurement precision of MMMRT. The results were as followings. The coefficients of determination of correction equation by linear and curvilinear regression analysis with comparing the MMMRT and standard moisture content were 0.946 and 0.968, respectively. The moisture content error of MMMRT and standard moisture content measured after the MMMRT were corrected by moisture content rate of every 5% using the correction equation by curvilinear regression analysis appeared with 0~0.5% and 0.9~1.8% respectively in the moisture content range of 15~20% and 20~25%.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.188-195
• /
• 2000

This study was conducted to measure the moisture content of powdered food using RF impedance spectroscopic method. In frequency range of 1.0 to 30㎒, the impedance such as reactance and resistance of parallel plate type sample holder filled with wheat flour and red-pepper powder of which moisture content range were 5.93∼-17.07%w.b. and 10.87 ∼ 27.36%w.b., respectively, was characterized using by Q-meter (HP4342). The reactance was a better parameter than the resistance in estimating the moisture density defined as product of moisture content and bulk density which was used to eliminate the effect of bulk density on RF spectral data in this study. Multivariate data analyses such as principal component regression, partial least square regression and multiple linear regression were performed to develop one calibration model having moisture density and reactance spectral data as parameters for determination of moisture content of both wheat flour and red-pepper powder. The best regression model was one by the multiple linear regression model. Its performance for unknown data of powdered food was showed that the bias, standard error of prediction and determination coefficient are 0.179% moisture content, 1.679% moisture content and 0.8849, respectively.

• Journal of Biosystems Engineering
• /
• v.6 no.1
• /
• pp.73-82
• /
• 1981

The physical properties of grain are very important for the design of handling, sorting, processing, and storage system. On the physical properties of grain, volume, bulk density, true density, specific gravity, and porosity arc the major factors affecting the thermal properties of grain. This study was conducted to determine experimentally the above physical properties of rough rice (3 Japonica-type, 3 Indica-type) and barley (covered, naked) as a function of moisture content ranged from about 10% to 25% (w.b). The results of this study are summarized as follows; 1. The volume of grain kernel increased with moisture content for both rice and barley. The volume of those grain kernel was in the range of $2.2068{\times}10^{-8}{\sim}3.3960{\times}10^{-8}m^3$ at the moisture content of 14%. 2. The bulk density of rice increased linearly with moisture content for Japonica-type rough rice and quadratically for Indica-type rough rice, but the bulk density of barley decreased linearly with moisture content. The bulk density of the grain was in the range of 501.14~689.13kg/$m^3$ at the moisture content of 14%. 3. The true density of whole grain decreased linearly with moisture content, and was in the range of 1019.49~1139.75kg/$m^3$ at the moisture content of 14%. 4. The porosity of rice decreased linearly with moisture content for Japonica-type rough rice and quadratically for Indica-type rough rice, but the porosity of barley increased linearly with moisture content. The porosity of the grain was in the range of 39.51~50.83% at the moisture content of 14%. 5. The regression equations of the physical properties such as volume, bulk density, true density, and porosity of the grain were determined as a function of moisture content.

• Journal of Biosystems Engineering
• /
• v.27 no.2
• /
• pp.125-132
• /
• 2002

In order to investigate the optimum moisture content of paddy for milling process, a series of tests were conducted by examining the recovery rate and whiteness of milled rice in relation with the various moisture content. Hwabong-byeo and Dongjin-byeo varieties which were major paddies cultivated in Korea were used for the experiment. The test was performed with small experimental milling machines. In order to minimize the unexpected factors, environment conditions were kept in constant during the experiment. As a result, the recovery rate of milled rice were varied as the changes in milling time and degree of whiteness. However, the recovery rate of milled rice increases as its moisture content increases untill a certain point of moisture content and decreases slowly afterward. This certain point can be called optimum moisture content for rice milling. Also, it has a different value depending on the variety. In this experiment, optimum moisture content of Hwabong-byeo and Dongjin-byeo were considered around 14.8% and 15.3%, respectively. It is not sure that these optimum moisture contents for the two varieties would assume the same values irrespective of harvest year and place. However, it could be concluded that the optimum moisture content for rice milling is around 15%(w.b.) for Hwabong-byeo and 15.5%(w.b.) for Dongjin-byeo, respectively.