• Composites Research
• /
• v.34 no.3
• /
• pp.174-179
• /
• 2021

Currently, fluid transfer steel pipes take a lot of time and expense to maintain all facilities due to new construction and painting or corrosion and aging. Therefore, this study was conducted for designing a CFRP pipe structure with high corrosion resistance and chemical resistance as a substitute for steel pipes. The helical/hoop pattern was cross-laminated to improve durability, and HNT was added to suppress the moisture absorption phenomenon of the epoxy. The HNT/CFRP pipe was manufactured by a filament winding process, and performed a mechanical property test, and a moisture absorption test in distilled water at 70℃. As a result, the highest bending strength was obtained when the hoop pattern was laminated with a thickness equivalent to 0.6% of the pipe. The 0.5 wt% HNT specimen had the highest moisture absorption resistance. Also, the delamination phenomenon at the interlayer interface was delayed, resulting in the lowest strength reduction rate.

• Journal of Biosystems Engineering
• /
• v.2 no.1
• /
• pp.25-32
• /
• 1977

This experiment was conducted in order to find out the drawing performance of a two-wheel tractor under different levels of the soil moisture and hardness, so as to obtain some basic data for improving their drawing performance. With fairly homogeneous soil, 5 levels of soil moisture contents (8, 13, 17, 20 and 23%) and 3 levels of soil hardness (0 , 2 and 4kg/$cm^2$) were selected for this experiment.The summerized results are as follows ;1. The draft force, on the hard soil (hardness ; 4kg/$cm^2$), had a distinct tendency to decrease with the increasing soil moisture. On the medium soil (hardness ; 2 kg/$cm^2$), and the soft soil (hardness ; 0kg$cm^2$), the draft force showed the highest when the moisture contents were within the range of 16-19%.But the maximum draft force, on the soft soil, was higher than that on the medium soil by 10 %. 2. The driving axle torque increased with increasing soil by 10 %. 3.The values of horizontal distance between the soil reaction point and axle shaft were within the range of 0~10cm , and it had the tendency to increase with the increasing soil moisture. Also, it s value was the largest on the hard soil and the smallest on the soft soil. 4.The tractive efficiency decreased with the increasing soil moisture. On the hard soil, the average value of tractive efficiency was higher than that on the medium soil by 19.0% and that on the soft soil was lower than that on the medium soil. 5.The traction ratio were within the range of 30 ~45%, and their changing tendency with respect to the soil moisture was similar to that in the case of the draft force. 6. The travel resistance ratio tended to increased with increasing soil moisture, and the highest value was found on the soft soil, and the lowest on the hard soil.

• International Journal of Highway Engineering
• /
• v.18 no.6
• /
• pp.123-130
• /
• 2016

OBJECTIVES : The objective of this research is to determine the moisture resistance of the freeze-thaw process occurring in low-noise porous pavement using either hydrated-lime or anti-freezing agent. Various additives were applied to low-noise porous asphalt, which is actively paved in South Korea, to overcome its disadvantages. Moreover, the optimum contents of hydrated-lime and anti-freezing agent and behavior properties of low-noise porous asphalt layer are determined using dynamic moduli via the freeze-thaw test. METHODS : The low-noise porous asphalt mixtures were made using gyratory compacters to investigate its properties with either hydrated-lime or anti-freezing agent. To determine the dynamic moduli of each mixture, impact resonance test was conducted. The applied standard for the freeze-thaw test of asphalt mixture is ASTM D 6857. The freeze-thaw and impact resonance tests were performed twice at each stage. The behavior properties were defined using finite element method, which was performed using the dynamic modulus data obtained from the freeze-thaw test and resonance frequencies obtained from non-destructive impact test. RESULTS : The results show that the coherence and strength of the low-noise porous asphalt mixture decreased continuously with the increase in the temperature of the mixture. The dynamic modulus of the normal low-noise porous asphalt mixture dramatically decreased after one cycle of freezing and thawing stages, which is more than that of other mixtures containing additives. The damage rate was higher when the freeze-thaw test was repeated. CONCLUSIONS : From the root mean squared error (RMSE) and mean percentage error (MPE) analyses, the addition rates of 1.5% hydrated-lime and 0.5% anti-freezing agent resulted in the strongest mixture having the highest moisture resistance compared to other specimens with each additive in 1 cycle freeze-thaw test. Moreover, the freeze-thaw resistance significantly improved when a hydrated-lime content of 0.5% was applied for the two cycles of the freeze-thaw test. Hence, the optimum contents of both hydrated-lime and anti-freezing agent are 0.5%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.37 no.4
• /
• pp.347-357
• /
• 2024

Oxide semiconductor gas sensors are widely used for detecting toxic, explosive, and flammable gases due to their simple structure, cost-effectiveness, and potential integration into compact devices. However, their reliable gas detection is hindered by a longstanding issue known as humidity dependence, wherein the sensor resistance and gas response change significantly in the presence of moisture. This problem has persisted since the inception of oxide semiconductor gas sensors in the 1960s. This paper explores the root causes of humidity dependence in oxide semiconductor gas sensors and presents strategies to address this challenge. Mitigation strategies include functionalizing the gas-sensing material with noble metal/transition metal oxides and rare-earth/rare-earth oxides, as well as implementing a moisture barrier layer to prevent moisture diffusion into the gas-sensing film. Developing oxide semiconductor gas sensors immune to humidity dependence is expected to yield substantial socioeconomic benefits by enabling medical diagnosis, food quality assessment, environmental monitoring, and sensor network establishment.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.2071-2072
• /
• 2011

Withstand voltage characteristics of the nanocomposites, as a material with excellent abrasion resistance and water resistance, low shrinkage upon curing with moisture even in very good adhesion, workability is not lost. In this study, the fusion of nanoparticles and the high functionality epoxy nano-composite material produces the electricity. Degeneration of the unit based on this power structure and breakdown characteristics, efficiency and cross-measurement system as closely related organisms that can be applied to the power plant electrical efficiency of the nano-composite material is designed to develop skills.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.14 no.5
• /
• pp.53-67
• /
• 2011

The major objective of this study was to quantify the effects of substrate depth and substrate composition on the development of sedum etc., in a sloped rooftop (6 : 12 pitch) environment during a 4-year period. The experiment was conducted from 2006 October to 2010 December under several conditions without soil erosion control : two substrate depth (5cm, 10cm), four substrate composition (A5N3C2, A3N3C4, A6C4, G5L3C2: A: artificial lightweight soil, N : natural soil, G : granite decomposed soil, C : leave composite, L : loess), four sloped roof direction ($E40^{\circ}W$, $W40^{\circ}N$, $S40^{\circ}W$, $N40^{\circ}E$). In this experiment 4 sedum etc., were used: Sedum sarmentosum, Sedum kamtschaticum, Sedum rupestre, Sedum telephium, flowering herbs (mixed seed : Taraxacum platycarpum, Lotus corniculatus, Aster yomena, Aster koraiensis), western grasses (mixed seed : Tall fescue, Creeping redfescue, Bermuda grass, Perennial ryegrass). The establishment factor had two levels : succulent shoot establishment (sedum), seeding (flowering herbs, western grasses). 1. Enkamat, as it bring about top soil exfoliation, was unsuitable material for soil erosion control. 2. Sedum species exhibited greater growth at a substrate depth of 10cm relative to 5cm. All flowering herbs and western grasses established only at a substrate depth of 5cm were died. A substrate depth of 5cm was not suited in sloped rooftop greening without maintenance. If additional soil erosion control will be supplemented, a substrate depth of 10cm in sloped rooftop greening without maintenance was considered suitable. 3. For all substrate depth and composition, the most abundant species was Sedum kamtschaticum. The percentage of surviving Sedum kamtschaticum was 73.4% at a substrate depth of 10cm in autumn 2007 one year after the roof vegetation had been established. But the percentage of surviving other sedum were 33.3%~51.9%, therefor mulching for soil erosion control was essential after rooftop establishment in extensive sloped roof greening was proved. To raise the ratio of plant survival, complete establishment of plant root at substrate was considered essential before rooftop establishment. 4. There was a significant interaction between biomass and substrate moisture content. There were also a significant difference of substrate moisture and erosion among substrate composition. The moisture content of A6C4 was highest, the resistance to erosion of A5N3C2 was highest among substrate composition. The biomass of plants were not significantly higher in A5N3C2 and A6C4 relative to A3N3C4 and G5L3C2, For substrate moisture and erosion resistance, A5N3C2 and A6C4 were considered suitable in sloped rooftop greening without maintenance. 5. There were significant difference among roof slope direction on the substrate moisture. Especially, the substrate moisture content of $S40^{\circ}W$ was lower relative to that of $N40^{\circ}E$, that guessed by solar radiation and erosion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.404-405
• /
• 2009

Insulation diagnostic tests for high voltage motor stator winding were conducted to analyze the insulation characteristics. Test motors were manufactured same factory and year(1996). Insulation characteristics of moisture winding are different from those of deteriorative winding. Insulation resistance and disscipation factor test results are sensitive to moisture winding. AC current, disscipation factor tip-up and PD test results are sensitive to deteriorative winding. Also, Capacitance value for stator winding insulation material has characteristic of increasing in moisture winding.

• Fibers and Polymers
• /
• v.3 no.1
• /
• pp.24-30
• /
• 2002

Wool yams were coated with conducting Polypyrrole by chemical synthesis methods. Polymerization of pyrrole was caned out in the presence of wool yarn at various concentrations of the monomer and dopant anion. The changes in tensile, moisture absorption, and electrical Properties of the yam upon coating with conductive polypyrrole are Presented. Coating the wool yams with conductive Polypyrrole resulted in higher tenacity, higher breaking strain, and lower initial modulus. The changes in tensile properties are attributed to the changes in surface morphology due to the coating and reinforcing effect of conductive Polypyrrole. The thickness of the coating increased with the concentration of p-toluene sulfonic acid, which in turn caused a reduction in the moisture regain of the wool yin. Reducing the synthesis temperature and replacing p-toluenesulfonic acid by anthraquinone sulfonic acid resulted in a large reduction in the resistance of the yam.

• Journal of the Regional Association of Architectural Institute of Korea
• /
• v.20 no.6
• /
• pp.55-61
• /
• 2018

This study improved the water repair materials of the polyacrylic system applied to concrete structures by controlling expansion, strengthening water resistance, and improving cohesiveness. The improved polyacrylate repair materials were evaluated against the existing products to verify their performance and level of improvement, and applied on-site to the concrete structures that are leaking the improved water. The verification method measured the presence of water leaks and the moisture content of concrete inside. Moisture levels were measured for two months before and after material installation, and at least 0.8 - 1.7% of humidity was reduced after installing polyacrylic resin, and no leakage was found.

• Journal of Biosystems Engineering
• /
• v.8 no.1
• /
• pp.9-16
• /
• 1983

This study was conducted to find out the effects of such parameters as specific draft resistance, slip rate, and fuel consumption rate on plowing performance in paddy fields spread with chopped rice straw. The plowing operation by an 8 P.S. power tiller was carried out in 6 different fields having the soil moisture content of 27~36 percent in dry basis in clay loam soil texture, and applying chopped rice straw of 10, 20, 30 and 60cm in length in the spring of 1982. The effects of soil hardness and moisture content on the plowing performance were also investigated. The results of the study are summarized as follows; 1. The minimum draft during the plowing operation was 110kg in the 30cm rice straw plot having the soil moisture content of 32 percent in dry basis. 2. The multiple regression equation of the specific draft(D) as a function of soil moisture content(M) and cutting length of rice straw(L) was obtained as follows. $D=14.1978-0.8565M+0.0661LxM-2.9685L+0.0133M^2+1.093L^2$ 3. In the 30cm rice straw plot with the soil moisture content of 32 percent in dry basis, the minimum specific draft resistance and the rate of slip were 0.35kg per $cm^2$ and 16 percent respectively. The specific draft resistance varied sensitively in accordance with the soil moisture content, and the slip rate of power tiller was dependent upon the cutting length of rice straw rather than the soil moisture content. 4. The highest plowing performance was 5.3 ares per hour at the soil moisture content of 35 percent and soil hardness of 10kg per $cm^2$. The relationship between the plowing performance and the soil moisture content was obtained by a quadratic equation. 5. The minimum fuel consumption rate in the plowing operation was recorded 6.5 liters per 10 ares in 30cm chopped rice straw plot with the soil moisture content of 32 percent in dry basis.