• Journal of Bio-Environment Control
• /
• v.18 no.4
• /
• pp.332-340
• /
• 2009

In this study, the thermal insulation effectiveness of the greenhouse insulators by the installation methods was investigated to find the right installation way of the insulation materials. Physical properties of the insulators such as thickness, air transmissivity, apparent density, ultraviolet rays cutoff ratio, reflectance, thermal conductivity, moisture absorptivity were evaluated and the insulation ability of the insulators were measured by the module experiments. For the same insulator, the insulation ability of the case with the outward direction of the black colored face, i.e., with the inward direction of the white colored face, was better than that of vice versa. The case of the black colored both surfaces was better than the case of the white colored both surfaces. For aluminium reflection material, the case with the outward direction of the lustre face, i.e., with the inward direction of the non-lustre face, was better than that of vice versa. For the same material with the inner thin polyethylene foam (or polyester) and the chemical wool, the case with the outward direction of the inner thin polyethylene foam (or polyester), i.e., with the inward chemical wool, was better than that of vice versa. Addition of the inner thin polyethylene foam increased the insulation effect very much.

• The Journal of Engineering Geology
• /
• v.22 no.1
• /
• pp.67-81
• /
• 2012

The physical, chemical, and biological properties of clogging materials formed within groundwater wells in the Mt. Geumjeong area, Busan, Korea, were characterized. The particle size distribution (PSD) of clogging materials was measured by a laser analyzer. XRD, SEM, and TEM analyses were performed to obtain mineralogical information on the clogging materials, with an emphasis on identifying and characterizing the mineral species. In most cases, PSD data exhibited an near log-normal distribution; however, variations in frequency distribution were found in some intervals (bi-or trimodal distributions), raising the possibility that particles originated from several sources or were formed at different times. XRD data revealed that the clogging materials were mainly amorphous ironhydroxides such as goethite, ferrihydrite, and lapidocrocite, with lesser amounts of Fe, Mn, and Zn metals and silicates such as quartz, feldspar, micas, and smectite. Reddish brown material was amorphous hydrous ferriciron (HFO), and dark red and dark black materials were Fe, Mn-hydroxides. Greyish white and pale brown materials consisted of silicates. SEM observations indicated that the clogging materials were mainly HFO associated with iron bacteria such as Gallionella and Leptothrix, with small amounts of rock fragments. In TEM analysis, disseminated iron particles were commonly observed in the cell and sheath of iron bacteria, indicating that iron was precipitated in close association with the metabolism of bacterial activity. Rock-forming minerals such as quartz, feldspar, and micas were primarily derived from soils or granite aquifers, which are widely distributed in the study area. The results indicate the importance of elucidating the formation mechanisms of clogging materials to ensure sustainable well capacity.

• Korean Journal of Soil Science and Fertilizer
• /
• v.28 no.4
• /
• pp.350-355
• /
• 1995

This study was conducted to use oyster shells, which have caused environmental problems in the coastal of Korea, as an agricultural material after processing. Physico-chemical components and neutralizing amount on the Ihyun silt loam of crushed oyster shell and slaked lime were examined. In field experiment, the properties of the soil, growth and yield of lettuce, cabbage, spinach, onion, red pepper and soybean were examined by the treatments of the shell(3.68ton/ha) or the lime (2.76ton/ha) with a randomized block design. Particle size of crushed oyster shell consisted of 73.4% of 1~60mesh and 26.6% larger then 61 mesh and contents of CaO, OM, and $P_2O_5$, etc. were 55.5%, 1.3%, and 0.29%, respectively. The requirement of the shell to neutralize the soil was 130~135% of the lime, but after 24months, it was the same. The application of the shell increased the contents of available $P_2O_5$ and $SiO_2$ exchangeable Ca in used soil. The shell tratment increased the leaf height, leaf width, etc. of the examined plants, and the yields 6~154% according to examined plants, as compared with the nonliminged, indicating that the shell possesses a great potential as an agricultural material with the same effectiveness as the lime.

• Journal of the Korean Wood Science and Technology
• /
• v.45 no.1
• /
• pp.126-138
• /
• 2017

This study was conducted to investigate the potential of chicken feather (CF), which is a by-product in poultry industry, as a raw material of wood adhesives. For the purpose, adhesive resins were formulated with NaOH- and $H_2SO_4$-hydrolyzed CF as well as crosslinkers, and then the properties and water resistance of the adhesive resins against hot water were measured. CF was made of mainly keratin-type protein, and no or very low content of heavy metals was detected. Hydrolysis rate of CF increased as NaOH concentration in hydrolysis solutions increased. However, in order to minimize the loss of adhesive property of protein itself by the severe hydrolysis of CF and to seek its proper hydrolysis conditions, NaOH concentrations in hydrolysis solution determined to adjust to 5%, 7.5% and 10%. In the NaOH-hydrolyzed CF, $H_2SO_4$-hydrolyzed CF as a hardener and crosslinker were added to formulate CF-based adhesive resins. Solid content of the resins ranged from 28.3% to 44.8% depending on hydrolysis conditions and type of crosslinker. Viscosity of the resins at $25^{\circ}C$ was very high. However, when the temperature of the resins was increased to $50^{\circ}C$, the viscosity decreased greatly and thus the resins could be applied as a sprayable resin. Retention rate measured to evaluate the water resistance of adhesive resins was the highest in the cured resin formulated with 5% NaOH-hydrolyzed CF and 5% $H_2SO_4$-hydrolyzed CF of 10% based on the solid weight as a hardener. Retention rate depending on crosslinkers added into adhesive resins was the highest phenol-formaldehyde (PF) followed by melamine-urea-formaldehyde (MUF) and formalin. The retention rate of CF-based adhesives formulated with 5% NaOH-hydrolyzed CF, PF and $H_2SO_4$-hydrolyzed CF of 10% and over did not differ statistically from that of commercial MUF resins. All of CF-based adhesives formulated with PF as a crosslinker and one with 5% NaOH-hydrolyzed CF of 55%, 5% $H_2SO_4$-hydrolyzed CF of 15%, and MUF of 30% on the basis of solid weight could be substituted for commercial urea-formaldehyde resins, From the results, CF can be used as a raw material of wood adhesives if hydrolyzed in proper conditions.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.46 no.5
• /
• pp.1-9
• /
• 2018

The purpose of this study was to identify differences of perceptions for gardens and parks between experts and the general public concerning several aspects including scope, scale, publicity, artistic and scientific nature, main materials, practicality and aesthetics, executive and management systems as well as legal understanding of garden and park. The properties of garden and park were derived through literature research, and the concept, similarity, and difference of gardens and the parks were recognized by the experts and the public viewpoint was clarified by questionnaire. As for the difference in the scope of the gardens and the parks, the expert group recognized it more widely than the general public. In general, the space recognized as a garden was the rooftop green space, and urban forests were recognized as a park. In addition, the general public recognized urban forests as gardens the same as they recognized parks, and the distinction was unclear. In the expert group, the perception that gardens were small and the parks were large was more prevalent. It was generally recognized that gardens were private spaces and the parks were public spaces. In the expert group, the gardens were more personal and the parks were more apparent to the public. In the general population, functional and scientific aspects rather than artistic creativity in both gardens and parks. In addition, both the general public and experts found that parks are more complex than gardens. The garden was centered on plant material, and the park was recognized as a center where the sculptural facilities were centered, or the plant material and the sculptural facilities were properly balanced. To the experts the view of the gardens was positive. Expert groups emphasized the aesthetics of the garden, and the parks were more practical, and the general population showed similar perceptions of utility and aesthetics when comparing gardens and parks. In addition, the utility of gardens in the general publics is more emphasized than the aesthetics of the park. Regarding the executive system the park was recognized as the public sector, and the difference was larger in the expert group. As for the management system, both experts and the general public perceive the management of the park or the garden to be carried out by the supporting organization, and it is necessary to discuss the diversification of the management subject. It is found that there is a certain difference in recognition with the mixture of concepts, and there is still a big difference in legal system and perception.

• Journal of the Korean Wood Science and Technology
• /
• v.45 no.5
• /
• pp.599-612
• /
• 2017

Human hair (HH) is produced as a waste from beauty parlor and barbershop. HH-based adhesives were formulated with NaOH-hydrolyzed HH, $H_2SO_4$-hydrolyzed chicken blood (CB) and PF as a crosslinking agent. Physicochemical properties and retention rate against hot water of the adhesives were measured to investigate the potential of HH as a raw material of wood adhesives. HH was composed of keratin-type protein of 80% and over. Ash of less than 0.1% was contained in HH. Among the amino acids included in HH, glutamic acid showed the highest content, followed by cysteine, serine, arginine and threonine. Solid content of the adhesives ranged from 33.2% to 41.8% depending on hydrolysis conditions of HH and PF type. Viscosity at $25^{\circ}C$ ranged from 300 to $600mPa{\cdot}s$ resulting in a sprayable adhesive. Retention rate against hot water measured to evaluate the water resistance of adhesives was the highest in the cured resin formulated with 5% NaOH-hydrolyzed HH and 5% $H_2SO_4$-hydrolyzed CB. Meanwhile, the molar ratio of formaldehyde to phenol in PF did not have a significant impact on the retention rate of HH-based adhesives. When the retention rates of HH-based adhesives were compared to those of conventional wood adhesive resins used for the production of wood-based panels extensively, HH-based adhesives formulated with 30 wt% PF showed lower retention rate than commercial urea-formaldehyde resin. However, when PF content was increased to 35 wt%, the retention rate greatly increased and approached to that of commercial melamine-urea-formaldehyde resin. Except for the results mentioned above, the analysis of economic feasibility suggests that HH-based adhesives can be used for the production of wood-based panels if HH is hydrolyzed in proper conditions and then the HH-based adhesives are formulated by the HH hydrolyzates with 35 wt% PF.

• Journal of Conservation Science
• /
• v.32 no.2
• /
• pp.167-178
• /
• 2016

Despite the size layer is an important part for conserving the artworks in the configuration of oil painting, the conservation scientific approaches of that have not been made yet. Therefore, this study produced standard samples on the basis of the analysis results of oil painting works, and carried out the evaluation of functions of the size layer materials. As a result of literature material, traditionally, animal glue was used for the size layer, whereas synthetic resin have been used in combination with animal glue since the modern age, in particular, it was identified that Polyvinyl Acetate(PVAc) was in general use. As a result of analysis of oil painting works, size layer was detected on the support and it was identified as animal glue. As a result of analysis based on Funaoka canvas for ground, it showed that the lead oxide and the titanium dioxide were the main constituents. On the basis of these results, standard samples were produced. As a result of evaluation on the functions of the size layer materials, in the case of the animal glue, stable result was observed in the shrinkag expansion rate, whereas slight weakness was observed in moisture proofing, color, and tensile strength, and dense cracks were found on surface. As for PVAc(A), moisture proofing, color, and the tensile strength exhibited stable results. Higher shrinkage rate was observed and the cracks with wide gaps were found on surface. As for PVAc(B), tensile strength, shrinkage expansion rate, and surface observation showed stable results, whereas moisture proofing property showed poor results. Different aspects were observed in each experiment, and this phenomena were considered to be due to the density and the adhesion properties between the hydrophilic and hydrophobic molecules in the size layer materials. The results are expected to be used as materials for the oil painting work conservation henceforth.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.6
• /
• pp.659-665
• /
• 2008

This study is about zeolite synthesis from the sewage sludge incinerator fly ash of "S" sewage treatment center located in Seoul. For this purpose, the properties of raw fly ash as starting material, the hydrothermal conditions for zeolite synthesis and the environmental applicabilities of synthesized zeolites were examined. Fly ash from sewage sludge incinerator has large quantities of SiO$_2$ and Al$_2$O$_3$ and their contents are 42.8 wt.% and 21.2 wt.% respectively. So fly ash is considered to be possible starting material for zeolite synthesis. The results from leaching test of fly ash showed that the concentration of hazardous metals were very low as compared with the Korea leaching standard of the Waste Management Law. But the concentration from total recoverable test of fly ash were higher than the fertilizer standard of Fertilizer Management Law. Major zeolite products synthesized by hydrothermal reaction are analcime in teflon vessel and zeolite P1 in borosilicate flask. Optimum conditions for the synthesis of analcime were 1 N of NaOH concentration, 16 hour of reaction time and 135$^{\circ}C$ of reaction temperature. For the zeolite P1 formation, the proper conditions were demonstrated to be 5 N of NaOH concentration, 16 hour reaction time and 130$^{\circ}C$ of reaction temperature in this study. Hazardous metal contents in the analcime product are similar with those in raw fly ash. In case of the zeolite P1, the contents are reduced to nearly a half. Raw fly ash and the analcime product showed NH$_4{^+}$ ion exchange capacity of 0$\sim$1.0 mg of NH$_4{^+}$g$^{-1}$ and 3.0$\sim$7.4 mg of NH$_4{^+}$g$^{-1}$, respectively. However, the zeolite P1 product reached exchange capacity to 14.6$\sim$17.8 mg of NH$_4{^+}$g$^{-1}$. This values are in the range of those of natural clinoptilolite and phillipsite. From this point of view, zeolite synthesis from sewage treatment sludge incinerator fly ash is a good alternative for solid waste recycling.

• Korean Journal of Soil Science and Fertilizer
• /
• v.35 no.5
• /
• pp.264-271
• /
• 2002

Nitrogen releasing characteristics of polymer-coated urea(PCU) that made acrylic synthetic resins were studied in incubated soil, water and paddy soil. Also, their correlations and degradation patterns of coating material were tested. Releasing rate of nitrogen from PCU decreased with increasing coating rate. N001(coating rate 8.5%) and N003(coasting rater 6.3%) were low releasing amount at the early stage, whereas N005(coating rate 4.8%) was released over 80% within 20 days. Relationship of the releasing rate between incubated soil($25^{\circ}C$) and paddy soil could be described as follows : $Y=-0.0011X^2+2.2931X-50.264(R^2=0.9884)$ for N001, $Y=-0.0016X^2+1.1587X+5.5064(R^2=0.9805)$ for N003 and $Y=-0.03X^2+6.499X-243.22(R^2=0.9422)$ for N005, respectively (Y: release rate at field condition, X: experiment period). Relationship of the releasing rate between incubated water($30^{\circ}C$) and paddy soil can be described as follows : $Y=0.0011X^2+2.2601X-25.329(R^2=0.9884)$ for N001, $Y=-0.0306X^2+4.4994X-76.307(R^2=0.955)$ for N003 and $Y=-0.0164X^2+3.7764X-108.22(R^2=0.9422)$ for N005. After 150 days, coating materials of N001, N003, and N005 in incubated soil were degraded approximately 23%, 22% and 15%, respectively. Also The scanning electron microscope examination of coating material revealed that particle surface became gradually shattered with the time after the soil treatment.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.23 no.3
• /
• pp.249-257
• /
• 2007

State of problem : The use of zirconium oxide all-ceramic material provides several advantages, including a high flexural strength(>1000MPa) and desirable optical properties, such as shading adaptation to the basic shades and a reduction in the layer thickness. Along with the strength of the materials, the cementation technique is also important to the clinical success of a restoration. Nevertheless, little information is available on the effect of different surface treatments on the bonding of zirconium high-crystalline ceramics and resin luting agents. Purpose : The aim of this study was to test the effects of surface treatments of zirconium on shear bond strengths between bovine teeth and a zirconia ceramic and evaluate differences among cements Material and methods : 54 sound bovine teeth extracted within a 1 months, were used. They were frozen in distilled water. These were rinsed by tap water to confirm that no granulation tissues have left. These were kept refrigerated at $4^{\circ}C$ until tested. Each tooth was placed horizontally at a plastic cylinder (diameter 20mm), and embedded in epoxy resin. Teeth were sectioned with diamond burs to expose dentin and grinded with #600 silicon carbide paper. To make sure there was no enamel left, each was observed under an optical microscope. 54 prefabricated zirconium oxide ceramic copings(Lava, 3M ESPE, USA) were assigned into 3 groups ; control, airborne-abraded with $110{\mu}m$ $Al_2O_3$ and scratched with diamond burs at 4 directions. They were cemented with a seating force of 10 ㎏ per tooth, using resin luting cement(Panavia $F^{(R)}$), resin cement(Superbond $C&B^{(R)}$), and resin modified GI cement(Rely X $Luting^{(R)}$). Those were thermocycled at $5^{\circ}C$ and $55^{\circ}C$ for 5000 cycles with a 30 second dwell time, and then shear bond strength was determined in a universal test machine(Model 4200, Instron Co., Canton, USA). The crosshead speed was 1 mm/min. The result was analyzed with one-way analysis of variance(ANOVA) and the Tukey test at a significance level of P<0.05. Results : Superbond $C&B^{(R)}$ at scratching with diamond burs showed the highest shear bond strength than others (p<.05). For Panavia $F^{(R)}$, groups of scratching and sandblasting showed significantly higher shear bond strength than control group(p<.05). For Rely X $Luting^{(R)}$, only between scratching & control group, significantly different shear bond strength was observed(p<.05). Conclusion : Within the limitation of this study, Superbond $C&B^{(R)}$ showed clinically acceptable shear bond between bovine teeth & zirconia ceramics regardless of surface treatments. For the surface treatment, scratching increased shear bond strength. Increase of shear bond strength by sandblasting with $110{\mu}m$ $Al_2O_3$ was not statistically different.