• Journal of the Korean Institute of Rural Architecture
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• v.23 no.4
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• pp.63-71
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• 2021

The purpose of this study was to investigate whether the standard models for rural housing and wooden housing model have performance for hygrothermal and to propose a way of improvement relevant to hygrothermal performance for those models. All of the models to be analyzed were found to have some parts that were absent of stability in terms of performance for hygrothermal. In the process of analyzing the causes and proposing improvement measures, the following conclusions were derived. Fist, The exterior surface of the structure should be composed of a structure with good moisture permeability, and for the interior surface, a variable vapor retarder paper should be applied in consideration of the reverse condensation phenomenon in summer. Second, in terms of performance for hygrothermal, applications of external insulation plaster finish to the exterior wall or of ventilation method using a rafter vent on the roof should be avoided. Third, a rain screen method with a ventilation layer should be applied to the exterior wall, and a method of constructing ventilation layer separated from the insulation layer with a vapor retarder paper should be applied to the roof. Fourth, the application of insulation materials having capillary action, such as wood fiber insulation board or cellulose insulation board, contributes to more stable performance for hygrothermal.

• Geomechanics and Engineering
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• v.35 no.1
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• pp.95-108
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• 2023

Soft soil ground is a crucial factor limiting the development of the construction of transportation infrastructure in coastal areas. Soft soil is characterized by low strength, low permeability and high compressibility. However, the ordinary treatment method uses Portland cement to solidify the soft soil, which has low early strength and requires a long curing time. Microbially induced carbonate precipitation (MICP) is an emerging method to address geo-environmental problems associated with geotechnical materials. In this study, a method of bio-cementitious mortars consisting of MICP and cement was proposed to stabilize the soft soil. A series of laboratory tests were conducted on MICP-treated and cement-MICP-treated (C-MICP-treated) soft soils to improve mechanical properties. Microscale observations were also undertaken to reveal the underlying mechanism of cement-soil treated by MICP. The results showed that cohesion and internal friction angles of MICP-treated soft soil were greater than those of remolded soft soil. The UCS, elastic modulus and toughness of C-MICP-treated soft soil with high moisture content (50%, 60%, 70%, 80%) were improved compared to traditional cement-soil. A remarkable difference was observed that the MICP process mainly played a role in the early curing stage (i.e., within 14 days) while cement hydration continued during the whole process. Micro-characterization revealed that the calcium carbonate filling the pores enhanced the soft soil.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.584-590
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• 2023

In this study, we focus on the recycling of cardboard waste and sugarcane bagasse (SCB) for the preparation of carboxymethyl cellulose (CMC) and its conversion into a biodegradable film. Sodium alginate (SA) was added to form a biodegradable composite film. SA was used to increase film permeability. Glycerol, which is a plasticizer, was used to increase the tensile strength (TS) and film expansion. To characterize the CMC, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were used. The addition of olive oil to the CMC-SA matrix highlighted its antimicrobial property against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). A slight decrease in tensile strength was observed with the addition of olive oil (OO), which improved the functional properties of the control films as well as lowered moisture content and water solubility. But considering all other factors, the composite films obtained from sugarcane bagasse and cardboard waste incorporated with olive oil are suitable for applications in the field of food packaging.

• Textile Coloration and Finishing
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• v.35 no.3
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• pp.179-187
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• 2023

In this study, we developed a microfiber-based flexible pressure sensor with high sensitivity and excellent skin breathability. A nonwoven fabric composed of microfibers was prepared by electrospinning, which resulted in excellent moisture permeability of the sensor (143 g∙m^-2∙h^-1). In particular, high-pressure sensitivity (0.36 kPa^-1) was achieved by introducing submicron structures on the microfiber surface by controlling the ambient humidity during electrospinning. The fabrication technology of the microfiber-based flexible pressure sensors reported in this study is expected to contribute to the commercialization of flexible pressure sensors applicable to long-term wearable health monitoring as well as virtual/augmented reality and electronic skin applications.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.432-439
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• 2004

Increase in water vapor barrier properties of sodium alginate films was studied by preparing composite films with fatty acids, i.e., lauric, palmitic, stearic, and oleic acids, and by treatment with 3% $CaCl_{2}$ solution for 3 min. Film thickness, surface color, microstructure, tensile strength (TS), elongation at break (E), water vapor permeability (WVP), water solubility (WS), and sorption isotherm of films were investigated. Microstructure of films observed with SEM was changed by fatty acid and $CaCl_{2}$ treatments. TS decreased 25-70% depending on fatty acid used, and increased 1.5- to 2-fold by $CaCl_{2}$ treatment. E decreased by both fatty acid and $CaCl_{2}$ treatments. Except oleic acid, WVP decreased significantly (p<0.05) by forming composite films with fatty acids, particularly with stearic acid, WVP decreased more than two-fold. WS also decreased by fatty acid and $CaCl_{2}$ treatments. In stearic acid, WS decreased about 30-fold by combined treatment of fatty acid and $CaCl_{2}$. Sorption isotherm showed typical biphasic pattern with deliquescent point of 0.75. Results of isotherms and BET monolayer moisture content indicated hydrophilicity of film decreased by $CaCl_{2}$ treatment.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.452-458
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• 2010

This study aimed at improving the packaging technology of Yukwa to improve the quality and extend the shelflife using secondary packaging. After packaging the Yukwa using an OPP film, P2, P3, and P4 packaging materials were applied secondarily. Various films including (1) P1: OPP (oriented polypropylene), (2) P2: P1+OPP/LLDPE (linear low density polyethylene), (3) P3: P1+PET (polyethylene terephthalate)/NY (nylon)/CPP (cast polypropylene) and (4) P4: P1+PET/AL (aluminum)/NY/CPP (P4) were used for packaging Yukwa. The experiment was conducted at $25^{\circ}C$ for 12 weeks. P1 showed the highest acid value score (1.26 mg KOH/g), and P3 had the highest peroxide value score (32.91 meq/kg) among all packaging groups. Nevertheless, these values did not exceed the guideline values of 2.0 g KOH/g and 40 meq/kg specified in the Korean food code. The overall color difference showed a tendency for decreasing Hunter 'L' values and increasing 'a' and 'b' values; however, no noticeable difference in the outer appearance was observed in any of the packaging treatments except in the P1 for greater than 10 weeks of storage. Some texture defects were observed in the Yukwa when the moisture contents dropped below 5%. The P4 packaging treatment had the lowest moisture permeability and showed the least rheological deterioration change, followed by P3 and P2. In conclusion, the use of a secondary packaging with less gas and moisture permeability was more effective for maintaining the quality and extending the shelf-life of Yukwa than other types of packaging material.

• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.4
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• pp.82-95
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• 1980

This paper complies the results of the studies so far made on the subsoil improvement of subsurface drainage systems for wet paddy fields (those were located in the Gum-Ho area in Kyung Buk province) which had poor permeability and a high water table. In general, a drainage problem is an excess of water on the ground surface which can effect the productivity and bearing capacity of the soil. With drain pipe systems, (According to their depths and spacing) it may be possible to correct that problem. The experimentation consisted of three test plots, two of which included drain pipe systems with varing depths and width spacing of the pipes. The third plot (C) was an ordinary plot being exempt of a drain pipe system. In detail, the depth of plot A was 80 cm, and the width spacings began at 2. Om and increased by 2. Om up to 10. 0m. The depth of plot B was 60cm and the width spacing was the same as plot A. These tests were performed to research specific details; such as crop yeild, bearing capacity of the soil, the amount of underdrainage, surface cracks, root distribution, the water table level, the consumptive water depth and the soil moisture content. The test period lasted three years, from 1977 thru 1979. The results obtained were as follows: 1. During the test period, the weather conditions for the area tested were in accordance with the annual average for that area. Furthermore the precipitation factor during the spring cultivation season, the intermediate drainage period and the harvest drainage period was of optimum conditions for controling surface cracks, because of less precipitation than evaporation. 2. The difference in the level of the ground water table in plots A and B was hardly noticable, but the difference in the test plots and the ord. plot was greatly noticable. The test plots (A, B) were 30 to 40cm lower than the ordinary plot. On the whole, the ground water table of the ord. plot always stayed at a level of 15-20cm beneath the surface of the soil, the ground water table of the test plot A showed The difference in the depth of the pipe lower than the test plot B, while the test plots showed a remarkable descending effect. 3. The soil temperature in plot A was slightly core than in plot B with a difference of 0. 47$^{\circ}$C, but plot A was 1. 6$^{\circ}$C higher than the ord. plot during the flooding period, but after drainage the temperature difference climed to 2. 0$^{\circ}$C. 4. During the 3rd test year, the values of the cracks were recorded with the values of 59cm in plot A, 42cm in plot B and 15cm in the ordinary plot. Plots A and B had increased 2.5 times the value of the first year while the ordinary plot had remained the same. 5. The root weight of the rice was measured at a value of 77.2 gr. for plot A, 73.5 gr. for plot B and 65.3 gr. for the ord. plot. Therefore, the root growths in plots A and B were much more energetic than in the ord. plot. 6. The consumptive water depth measured during the 3rd year resulted in the values of 26. 0mm per day for plot A, and 24.9 mm per day for plot B, respectively. Therefore, both plot A and plot B maintained the optimum consumptive water depths, but the ordinary plot only obtained the value of 12.3 mm per day, which clearly showed less than the optimum consumptive water depth which is 20 to 30 mm/day. 7. The soil moisture content is in direct relationship to the ground water level. During drainage, test plot A decreased in its ground water level much more rapidly than the other two plots. Therefore, plot A had a much less soil moisture content. But this decreased water level could be directly effected by the weather conditions. 8. The relationship between the bearing capacity and the soil moisture content were directly inversely proportional. It can be assumed that the occurence of soil creaks is limited by the soil moisture content. Therefore, the greater the progress of the surface creaks resulted in a greater bearing capacity. So, tast plot A with a greater amount of surface cracks than the other test plots resulted in a greater bearing capacity. But, the bearing capacity at the harvest season could be effected by the drainage during the intermediate drainage period and by the weather conditions. 9. Comparing the production of the test plots to the ord. plot; there was an increased value of 840kg for plot A, 755kg for plot B and 695kg for the ord. plot in the rough rice. Therefore, plot A had an increase of 20% over the ordinary plot. The possibility of producing double crops was investigated. The effects on barley production in the test plots showed a value of 367kg per 10 acres, which substantiated the possibility of double crops because that value showed an increased value over the average yearly yield for those uplands. 10. So as a result, it can be recommended that by including a drain pipe system with the optimum conditions of an (80cm centimeter) depth and a (l0m) spacing will have a definite positive effect on the over all production capacity and quality of wetpaddy fields.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.1
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• pp.73-86
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• 2014

Persimmon juice dye-printed fabrics with printing were used for a Galot one-piece dress. The Galot dress was assessed in comparison to a white undyed one-piece dress of the same design through a wearing test conducted in a climatic chamber with an air temperature of $30{\pm}1^{\circ}C$, $50{\pm}5%$ R.H, and 0.2m/sec air movement on 4 healthy female subjects in their 20s. The subjects went through a 30-min stable period, a 30-min exercise of walking on a $5^{\circ}$ slope treadmill at 70m/min period, and a 20-min recovery period. In addition, a physiological reaction and subjective sensation were estimated. The results showed that significant differences were mostly observed from a sweating period that occurred during the latter half of the exercise. More specific results are as follows. First, skin temperature on the chest and mean skin temperature were significantly higher (p<.01) in rayon dyed sample dresses. Second, micro-humidity on the back showed a significant difference (p<.01). Both cotton and rayon persimmon juice dyed sample dresses produced lower microhumidity than their counterparts and as for cotton the difference occurred over the entire experimental period; however, it occurred after the middle of the exercise period for rayon. Third, the sweating rate on the back decreased in both cotton and rayon with persimmon juice dye but no significant difference was observed. Fourth, subjective three sensations revealed significant differences between cotton and rayon (p<.01), indicating that the subjects felt more cool, dryer and more comfortable in a cotton Galot. As described above, the analysis of physiological responses and the subjective sensation of undyed and dyed clothing shows the effect of persimmon juice dyeing. Persimmon juice dyeing also seemly increased air permeability, moisture regain and permeability facilitating body heat ventilation, as micro-humidity and sweat rate were lowered. However, this was not shown consistently in subjective responses on comfort especially when wearing rayon dresses.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.1
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• pp.29-34
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• 1987

This experiment was designed to find out the effects of soil conditioner, Polyacrylamide (PAM) and Bitumen, on the changes of soil aggregate properties and crop yields. The soil conditioners were treated at the rates of 0.5% and 1% to sandy loam and silty clay loam soils. The aggregate stability, wetting angle, mean weight diameter and air permeability were analyzed. Pot experiments were carried out to investigate the soybean growths and soil property changes after the soil conditioners were sprayed to surface soils. Soil aggregate stability was increased remarkably by the soil conditioner, PAM and Bitumen, treatments. PAM was more effective in sandy loam than silty clay loam, but Bitumen was better in silty clay loam. Wetting angle of the soil was changed slightly by PAM treatment, but it was greatly changed to hydrophobic by Bitumen treatment. Air permeability, water infiltration rate and moisture retention of the soils were increased by surface application of soil conditioners, PAM and Bitumen. The growths of soybean in conditioner applicated pots were better than those of untreated pots from early stage, and the yields were increased 6-13%.

• Journal of the Korean Wood Science and Technology
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• v.41 no.3
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• pp.234-246
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• 2013

It was found that test piece heated rapidly by 3 kW microwave for 5 minutes satisfies the targeted temperature and the percentage of moisture content, and the highest rate of weight increase is obtained in case of 120 minute immersion in the mixture of phosphates and heterocyclic compounds, from the result of such analysis as: kiln drying schedule, flame retardent by flammability test, insect resistance by termites, and permeability of combined penetrant for the wood after assigning multifunctional finish by immersing conifer structural frame, which is used for the frame work of wooden house and indoor/outdoor finishing in flame retardant and insect repellent materials mixture with the remaining heat of microwave. In addition, after a test of flame retardent treated item, it was identified that every mixture of phosphates corresponds with the standards of flame retardent, and upon investigation of moritality of 7 days after putting termites, it was showed that test piece immersed in the mixture of phosphates and heterocyclic compounds has the best characteristics, showing over 96% of high moritality. From the analysis of inward permeability of combined penetrant for the wood, it was decided that excellent performance in the flame retardent and insect resistance of the wood revealed due to full penetration of combined penetrant as it was found that combined penetrant penetrated through the whole inner cells of the wood.