• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.197-206
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• 2002

Volumetric soil water contents through a soil profile were monitored to identify the effects of tillage systems and soil physico-chemical characteristic on soil water movement from the soil profile. Water content profiles under no tillage (NT) and conventional tillage (CT) practices were compared at two commercial farms in central Illinois from 1992 through 1994, using neutron-scattering techniques in weekly intervals during each growing season. The volumetric water content of surface soil layers was affected more by tillage systems and rainfall amounts, whereas that of the subsoil layers was more strongly affected by soil types. Soil water percolated faster through Saybrook and Catlin soils than through Drummer, Flanagan, and Ipava soils because Saybrook and Catlin soils have lower clay content and water-retention capacity and higher permeability than Drummer, Flanagan, and Ipava soils. Increased soil organic matter (SOM) in Drummer, Flanagan, and Ipava soils would be attributable to the higher soil water retention than other soil types. Soil water contents in the corn root zone were consistently higher under CT plots than under NT plots.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.2
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• pp.34-41
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• 1999

Adsorption of cationic polyacrylamide dry strength resins onto the surface of papermaking fibers and fines is critical for their effective utilization. Since dry strength resins are frequently employed when recycled fibers containing a great deal of fines are used as a raw material, their adsorption characteristic onto the recycled fiber fines is of great importance. In this study, effects of recycling on adsorption characteristics of cationic polyacrylamide onto primary and secondary fines were examined. Never dried bleached hardwood kraft pulp was beaten and dried for recycling. In each recycling step the adsorption characteristic of a cationic PAM onto primary and secondary fines was evaluated by kjeldahl nitrogen analysis method. The influence of recycling on water retention value and carboxyl content along with the sheet density and tensile strength was examined. Secondary fines of never dried pulp adsorbed twice as much of C-PAM as the primary fines, however, the adsorption capacity of the secondary fines decreased rapidly during the course of recycling and showed lower adsorption capacily than primary fines.

• Journal of the Korean Society of Food Culture
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• v.28 no.1
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• pp.107-113
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• 2013

Yacon (Smallanthussonchifolius) is a root crop that contains high amounts of fructo-oligosaccharides (FOS). FOS has a sweet taste, is low in calories, and is known to promote intestinal tract health. In this study, various yacon concentrates were substituted for sugar in white pan bread to obtain healthy benefits from the use of FOS. The quality characteristic changes during storage of the white pan breadswith 0, 25, 50, 75 and 100% of added yacon concentrates instead of sugar were investigated. During storage, the water contents and water activities of the breads made with high amounts of yacon concentrates changed less than in those made with only sugar. The hardness and chewiness of the breads made with high amounts of yacon concentrates had lower values than those made with only sugar. Thus, bread made with yacon concentrates might exhibit increased moisture retention and decreased aging velocity. The substitution of yacon concentrates for sugar in pan bread improved the bread quality.

• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.49-60
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• 2010

Unsaturated permeability function is an important factor in the design and analysis of various unsaturated soil structures. Generally the permeability characteristics decrease as the mat ric suction increases and the trend is similar to water retention characteristics of a soil. The permeability of unsaturated soils can be obtained directly by laboratory tests or indirectly by estimation methods from other soil properties. For unsaturated soils sampled from 7 areas in KOREA, SWCCs and unsaturated permeability functions were obtained by experimental tests. The unsaturated permeability results were also compared with the unsaturated permeability functions derived from the SWCCs theoretically. However, the current estimation models of unsaturated permeability function did not express the unsaturated permeability characteristics. Therefore, the FXK-M permeability function was modified to predict more accurate permeability functions for Korean weathered soils using a correction factor that can be calculated from the air-entry value of SWCC. The new estimation model resulted in good agreements for all tested soils.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.5
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• pp.695-705
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• 2024

As a result of Typhoon Hinnamnoh, several slope failures occurred in the Pohang region, it is necessary to perform infiltration and slope stability analyses due to the actual rainfall. In the failed sites, samples were collected, and the hydro-mechanical properties of unsaturated soil were examined. Modeling the actual behavior using a single-mode function characteristic curve was found to be inadequate, leading to the adoption of a dual-mode function characteristic curve. The dual-mode function showed better agreement with the water retention test data. We calculated the unsaturated hydraulic conductivity for single and dual modes and performed rainfall-induced infiltration analysis. The variations in saturation and pore water pressure were calculated due to rainfall for three landslide-prone areas, Stability analysis based on effective stress of unsaturated soil was conducted, and safety factors were computed over time steps. The dual-mode model successfully reproduced landslides triggered by Typhoon Hinnamnoh, while the single-mode model exhibited a minimum safety factor of 1.2-1.3, making slope failure unpredictable. The dual-mode model accurately predicted instability in the slope by appropriately accounting for pore water pressure variations during Typhoon.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.1
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• pp.65-73
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• 1986

Experiment have been conducted about thin oxide characteristics according to O2/N2 ratio needed for EEPROM cell fabrication. As a result, we think that there is no problem even if we grow oxide layer with large O2/N2 ratio and short exidation time and when the water is implated by As before oxidation, the oxide breakdown field is about IMV/cm lower than that is not implanted. Especially, the thin oxide characteristic seems to be affected largely by wafer cleaning and oxidation in air. On the basis of these, tunnel type EEPROM cell is fabricated by 3um CMOS process and its characteristic is studied. Tunnel oxide thickness(100\ulcorner is chosen to allow Fowler-Nordheim tunneling to charge the floating gate at the desired programming voltage and tunnel area(2x2um\ulcorneris chosen to increase capacitive coupling ratio. For program operation, high voltage (20-22V) is applied to the control gate, while both drain and source are gdrounded. The drain voltage for erase is 16V. It is shown that charge retention characteristics is not limited by leakage in the oxide and program/erase endurance is over 10E4 cycles of program erase operation.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.787-798
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• 2017

This is a study on characteristics according to the material of sheet-type mask packs being sold on the market. The absorption capacities of water soluble components such as purified water, 1.3-propanediol, 1.3-butylene glycol, glycerine, and hyaluronic acid are compared with that of various oils including cyclomethicone, dimethicone, phytosqualane, caprylic capryl triglyceride, grape seed oil, and macadamia nut oil. As a result, all of the water soluble components except purified water showed higher moisture absorption capacity as the viscosity increased. And in case of oil, all oil showed higher oil absorption capacity according to the viscosity. During this test, the mask sheets with the type of acetic acid fermented bio-cellulose showed 500~1,000 times or more absorption capacity on water soluble wetting agent or all oils, which is due to the fine mesh structure seen in the 5,000x enlarged photograph at surface structure. This mesh structure was well recognized on the cross section and these structural features enhance the absorption capacity of water and oil. It is also believed that largely contained water-soluble components and oils facilitate the discharge over time. In addition, since each mask sheet shows their characteristics according to their material, it is intended to be a basic research for manufacturing mask packs good for skin.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.742-749
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• 2009

To examine the characteristics of the nutrient release from the sediments in two reservoirs, Lake Paldang and Lake Cheungpyeung, we analyzed physical and chemical properties of the sediments and calculated the nutrient release rates from the sediments. The particle properties of sediments in Lake Paldang changed from silt to sand after summer rainy season, especially in the water area of the Kyeungan River where the water depth was shallow and the width of river was narrow. The sediments in Lake Cheungpyeung had higher contents of silt and clay than in Lake Paldang, and the particle size was not much different before and after rainfall. The release rates of nutrients in two lakes varied with the kind of nutrients and the season. The release rates of DTN and ${NH_4}^+-N$ in Lake Paldang were faster in spring than autumn. But the Lake Cheungpyeung showed similar values of release rates before and after summer rainy season. ${NO_3}^--N$ and phosphorous were not released from sediments or were absorbed into sediments all the time in two lakes. Compared with other lakes, the sediments of two lakes consisted of bigger particles and had a lower organic matters content than other lake-type reservoirs. Due to the short hydraulic retention time and no stratification throughout the year in Lake Paldang and Lake Cheungpyeung, the release rates of nutrients from sediment in these reservoirs were lower than other lakes and this seems to be a typical characteristic of river-type reservoirs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.173-178
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• 2010

The ice storage system uses water for low temperature latent heat storage. However, a refrigerator capacity are increased and COP are decreased due to supercooling of water in the course of phase change from liquid to solid. This study investigates the cooling characteristics of the TMA-water clathrate compound including TMA (Tri-methyl-amine, $(CH_3)_3N$) of 20~25 wt% as a low temperature latent heat storage material. The results showed that the phase change temperature are increased and the supercooling degree and the specific heat are decreased according to the weight concentration of TMA increased. Especially, the clathrate compound containing TMA 25wt% has the average phase change temperature of $5.8^{\circ}C$ and the supercooling degree of $8.0^{\circ}C$, retention time of liquid phase for 651sec and specific heat of 3.499 kJ/kgK in the cooling process. This expressed good than different concentration of TMA cooling characteristic. Like this, to apply TMA 25wt%-water clathrate compound is determined by advantageous as the low temperature latent heat storage material.

• Journal of Korean Society of Disaster and Security
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• v.11 no.2
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• pp.83-89
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• 2018

The significant sedimentation at the estuary in the eastern coast of Korea frequently causes river mouth occlusion where disconnection between the river and sea is observed. River mouth occlusion causing watershed retention raises the environmental risk of the area as it impairs water quality and threatens the area's safety in the event of floods. This study proposes a plan to maintain stability of river channel and flow of flood discharge at the estuary with loss of its function for disaster prevention. To this end, the study tries to change the location and width of stream path, focusing on the center line of stream near the sand bar of river mouth. This allows to identify a shape of stream path that leads the most stable flow. To review the result, this study uses the SRH-2D, a model for two-dimensional hydraulic analysis, and conduct numeric simulation. The simulation result showed that the most effective plan for maintaining the stable flow of running water without having the area sensitive to changes in hydraulic characteristics is to lower the overall river bed height of the sand bar near the center line of stream to a equal level.