• Journal of Soil and Groundwater Environment
• /
• v.29 no.4
• /
• pp.21-31
• /
• 2024

Sumgol in Jeju Island plays a significant role in groundwater recharge due to its permeable hydrogeological characteristics. However, a quantitative assessment of the interrelationship between rainfall characteristics and rainwater inflows into Sumgols has not yet been conducted. Therefore, this study examined the characteristics of rainwater inflow into three Sumgols located in the eastern and western regions of Jeju Island and assessed hydrogeologic factors influencing these inflows. During two rainfall events, the studied locations in Sumgol exhibited different characteristics of rainwater inflows, despite experiencing similar rainfall events. Additionally, the delay time for rainwater to reach the Sumgol locations after the rainfall was influenced more by rainfall intensity than by cumulative amount of rainfall. In Sumgols located in non-volcanic ash soil with low hydraulic conductivity, such as those in agricultural areas, rainwater inflows were observed even with small rainfall and low rainfall intensity. This study suggests that rainfall intensity, soil characteristics, permeability of lava flows, and land use are key factors influencing rainwater inflow into Sumgols, revealing that soil characteristics and the permeability of lava flows have a greater impact on surface runoff than land use.

• Journal of the Korean GEO-environmental Society
• /
• v.8 no.3
• /
• pp.59-65
• /
• 2007

Excess pore pressures in low permeability soils may not dissipate quickly enough and decrease the effective stresses inside the soil, which in turn may cause a reduction of the shear strength at the interface between the soil and the reinforcement in MSE walls. For this condition the dissipation rate of pore pressures is most important and it varies depending on wall size, permeability of the backfill, and reinforcement length. In this paper, a series of numerical analysis has been performed to investigate the effect of those factors. The results show that for soils with a permeability lower than $10^{-3}cm/sec$, the consolidation time gradually increases. The increase in consolidation time indicates the decrease in effective stress thus it will result in decrease in pullout capacity of the reinforcement as verified by the numerical analyses. It is also observed that larger consolidation time is required for longer reinforcement length (longer drainage path).

• Journal of the Korea Institute of Building Construction
• /
• v.4 no.1
• /
• pp.119-126
• /
• 2004

Generally, reinforced concrete is one of the most commonly used structural materials and it prevents corrosion of steel bar by high pH of interior, But, as time elapsed, reinforced concrete structure become deteriorated by many of combined deterioration factors and environmental conditions. And, there are large number of deteriorate mechanism of the reinforced concrete structure and it acts complexly. It is recognized that steel bar corrosion is the main distress behind the present concern regarding concrete durability. In this study, to institute combined deterioration environments, established acceleration condition and cycle for combined deterioration environments has a resemblance to environments which are real structures placed. After that to confirm corrosion properties of reinforced concrete due to permeability with covering depth and types of surface cover under combined deterioration environments, measured carbonation velocity coefficients, chloride ion diffusion coefficients, water absorption coefficients, air permeability coefficients and electric potential, corrosion area ratio, weight reduction, corrosion velocity of steel bar. The results showed that an increase in age also decrease carbonation velocity coefficients, increase Chloride ion diffusion coefficients and increases water absorption coefficients. As well, an increase in age also increases corrosion of steel bar. Data on the development of corrosion velocity of steel bar with types of surface cover made with none, organic B, organic A, inorganic B, and inorganic A is shown. As well, permeability and corrosion velocity of steel bar with covering depth is superior to 10mm than 20mm. And it is confirmed permeability and corrosion properties of steel bar are closely related.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.4
• /
• pp.395-398
• /
• 1999

Chitin was isolated from red snow crab (Chinonecetes japonicus) and deacetylated by boiling alkaline solution to produce chitosan. The physical properties of chitosan solution and its film properties was examined, As the molecular weights of chitosan was increased from 297Kpa to 319Kpa, the tensile strength, degree of elongation and water permeability of chitosan film were increased. As the degree of deacetylation of chitosan was increased, the tensile strength, the degree of elongation and water permeability of chitosan film were increased. As the concentration of chitosan solution was increased, the degree of elongation and water permeability of film were increased, whereas the tensile strength of film was decreased, As the pH of chitosan solution was increased, the tensile strength and water permeability of film were decreased, whereas the degree of elongation of film was increased.

• Polymer(Korea)
• /
• v.38 no.6
• /
• pp.687-693
• /
• 2014

Poly(ether-block-amide) 1657 (PEBAX 1657) blended membranes with molecular weight 400 poly(ethylene glycol) (PEG 400) were prepared and their permeability was tested for the gases $N_2$, $O_2$, $CH_4$, $CO_2$, and $SO_2$ by the time-lag method. The permeation characteristics were investigated in terms of diffusivity and solubility, which are dominant factors for gas transport. With the addition of PEG 400, the permeability of all the gases increased and also the ideal selectivity for several pair gases was enhanced. In particular, selectivity for $CO_2/N_2$ ranged from 53.2 (pristine PEBAX 1657 membrane) to 84.1 (50% PEG 400 added), for $SO_2/CO_2$ from 38.9 to 50.7, and for $CO_2/CH_4$ from 17.7 to 31.4. The increase of both permeability and selectivity is mainly because of the increase of solubility of the gases, especially $CO_2$ and $SO_2$. To obtain durability against water vapor, glutaraldehyde (GA) was added to the PEBAX 1657/PEG 400 blended membranes. As a result, permeability decreased owing to a reduction of the free volume and ether oxide units, which are the main factors in elevating the permeability for the blended membranes, and selectivity decrease however; we believe that the durability of the resulting membranes would be increased.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.10a
• /
• pp.270-275
• /
• 2009

Sound absorption characteristics of membrane system which are used in stadiums and arenas were investigated. Theoretical studies on acoustic properties of single and double leaf permeable membrane conducted. Also, experimental studies on sound absorption characteristics of combined membrane system that is composed of outer and inner membrane material were conducted. In this study, sound absorption characteristics of each membrane were investigated by experiments in reverberation chamber. 4 types of permeable membranes and a non-permeable membrane were used for experiments. Air space behind membrane material and tension on the membrane was varied. Sound absorption performance of permeable membrane materials was confirmed. As increasing air space behind the membrane material, sound absorption coefficient was increased. In a resonance absorption frequency band sound absorption coefficient varied more dramatically. Sound absorption characteristics were flat in mid and high frequency range and sound absorption coefficient was from 0,3 to 0,5. Also sound absorption coefficient was increased by the increment of surface density and air permeability of membrane. However, over the certain value of air permeability, sound absorption coefficient was decreased. These results can be used as design factors and method for the room acoustic design of dome-stadiums and large free-form buildings.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.223-226
• /
• 1999

The purpose of this study is no examine the combination effect on strength preperties of water-permeable concretes mixed with redispersible polymer, silica fume and polypropylene fibers for overlay in pavement. The water-permeable concrete with a water-cement ration of 25%, polymer-cement ratios of 0 to 10%, silica fume contents of 0 to 10% and polypropylene fiver contents of 0 to 1.5% are prepared, and tested for flexural strength, compressive strength and water permeability. It is concluded concretes are obtained at a polypropylene fiber content of 1.0% and a silica fume content of 10% with a void filling ratio of 50%. And the water-permeable concretes with a flexural strength of 14.1~28.0kgf/$\textrm{cm}^2$, a compressive strength of 71.2~128.0kgf/$\textrm{cm}^2$, and a coefficient of permeability of 1.22~2.52cm/s at a void filling ratio of 30% can be prepared. Also water-permeable concretes having flexural strength of 24.9~57.9kgf/$\textrm{cm}^2$, a compressive strength of 83.8~268.5kgf/$\textrm{cm}^2$, and a coefficient of permeability of 0.24~1.04cm/s at a void filling ratio of 50% can be prepared in the consideration of the mix proportioning factors.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.307-312
• /
• 1999

The purpose of this study is to ascertain the strength properties of water-permeable concrete with redispersible polymer powder, silica fume and polypropylene fibers. The water-permeable concrete using rediapersibel polymer powder with a water-cement ratio of 25%, polymer-cement ratios of 0 to 10%, silica fume contents of 0 to 10% and fiber contents of 0 to 1.5% are prepared, and tested for flexural strength, compressive strength and water permeability. From the test results, improvements in the strength properties of the water-permeable concrete due to the addition of the redispersible polymer powder, silica fume and fibers are discussed. It is concluded from the test results that the superior flexural and compressive strengths of water-permeable concretes are obtained at a propylene fiber content of 1.0% with a void filling ratio of 50%. And, the water-permeable concrete having a flexural strength of 15.6~28.4kgf/$\textrm{cm}^2$, a compressive strength of 63.5~120.6kgf/$\textrm{cm}^2$, and a coefficient of permeability of 1.14~1.70cm/s at a void filling ratio of 30% can be prepared. Also water-permeable concrete having a flexural strength of 35.6~57.9kgf/$\textrm{cm}^2$, a compressive strength of 164.0~290.0kgf/$\textrm{cm}^2$, and a coefficient of permeability of 0.19~1.04cm/s at a void filling ratio of 50% can be prepared in the consideration of the mix proprotioning factors.

• Journal of Korean Society of Water and Wastewater
• /
• v.32 no.5
• /
• pp.453-460
• /
• 2018

The impact of sodium hydroxide, which is one of chemicals of clean in place (CIP) for removing membrane fouling, on the PVDF membrane is reviewed with respect to physical/chemical structural change, the permeability affected therefrom. Based on the cleaning concentration applied in membrane water treatment facilities, 10% of accumulated defluorination was confirmed up to 166g.hr/L which reflects the exposure time. However, membrane resistance was confirmed to be reduced by about 10%. Through FT-IR and EDS analysis, reduction of F and change of are confirmed as factors that affect the permeability of membrane. Membrane resistance, which affects permeability, is affected by loss of additives for hydrophilicity, rather than defluorination of PVDF material. Therefore, in order to check membrane degradation degree, an accelerated test by NaOH was carried out, loss of additives was confirmed, and then PVDF inherent characteristic was observed.

• Journal of the Korean Home Economics Association
• /
• v.37 no.12 s.142
• /
• pp.193-203
• /
• 1999

This study was executed to show influence of material and property of sportswear to physiological responses of body and comfort sensation and to supply basic research data about comfortable sportswear Trainning wear was manufactured with cotton(C) and hygroscopically treated polyester material (FP), and its properties of material were measured. Then rectal temperature, skin temperature, heart rate, weight loss, clothing microclimate and subjective sensation was estimated with study of wearing with these sportswear and examined the influence that it got to physiological responses of body and sensation. Health adult men were selected for subjects and executed at climatic chamber of temperature, $20\pm2^{\circ}C and humidity, $60\pm5%$ R.H. Conclusively sportswear of hygroscopically treated polyester is a favorable functional material. So far factor that affect to physiological comfort sensation has been explained mostly by moisture regain but in our experiment, it turned out that air permeability, water absorption velocity and dynamic oater absorption etc. were affecting factors. So according to this result, air permeability and moisture permeability should be considered with transmittance of temperature moisture for development of comfort material.