• Fire Science and Engineering
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• v.28 no.4
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• pp.57-63
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• 2014

This study was performed to test the combustive properties of Medium Density Fibreboard (MDF) specimens treated with piperazinomethyl-bis-phosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), and N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (MDEDAP). MDF Plates were painted in three times with 15 wt% solution of the alkylenediaminoalkyl-bis-phosphonic acids at the room temperature, respectively. After drying specimen treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). It was indicated that the specimens treated with chemicals showed the later time to peak mass loss rate ($TMLR_{peak}$) = (340475) s than that of virgin plate by reducing the burning rate. In adition, the specimens treated with chemicals showed the higher $CO_{mean}$ production (0.0883~0.0963) kg/kg than that of virgin plate. Especially, the specimens treated with chemicals showed the higher mean smoke extinction area ($SEA_{mean}$) ($5m^2/kg{\sim}21.5m^2/kg$) than that of virgin plate. Thus, It is supposed that the combustion-retardation properties were improved by the partial due to the treated alkylenediaminoalkyl-bis-phosphonic acids in the virgin MDF Plate. However, It gave a negative effect on smoke reduction.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.277-291
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• 1983

In order to investigate the shear characteristics of earth structure after construction. Four sample soils with different gradation were selected and compacted under the optimum moisture content and the maximum dry density. And the direct shear test and the triaxial compression test were performed with those sample soils under various pre-compression loads. The results were summarized as follows; 1. With the increase of the percent passing of No. 200 sieve, the cohesion of soil increased regularly and the internal friction angle of soil decreased with slow ratio. 2. The pre-compression increased the shear strength of compacted cohesive soil. The increase of cohesion was very apparent but the internal friction angle didn't show such regular tendency. 3. With the increase of pre-compression load, the slope of stress-strain curve showed steep at the early stage of horizontal strain. The vertical strain was small at the compression stage and big at the expansion stage. 4. When the vertical stress of shear test with increase in the horizontal strain was small, stress ratio(shear stress vs. vertical stress) of sample showed the largest value and the slope of stress ratio curve showed also steep. 5. When the sample was had the same condition, the cohesion of soil showed bigger value in the triaxial compression test and the internal friction angle of soil showed bigger value in the direct shear test.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.433-444
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• 1975

This study was conducted to investigate the strength of lime soil mixtures for varied' curing temperatures(20, 30, 40, 50, $60^{\circ}C$) and lime content (3, 6, 9, 12%) in four lime-stabilized soils(KY : Sand, MH : Sand, SS: Sandy loam. JJ : Loam). The experimental results obtained from unconfined compressive strength tests are as follows; 1. The optimum moisture content increased and maximum dry density decreased with the increase of the lime content. 2. The lime content for the maximum strength of SS and JJ soils showed at the 9 percent lime content, but KY and MH soils didn't show the tendency of increase and decrease by the lime content and curing period. The rate of decrease of the soaked unconfined compressive strength showed the lower value in accordance with lime content. 3. According to increase in curing temperatures in curing temperatures at 30, 40, 50, $60^{\circ}C$, the unconfined compressive strength of lime soil mixtures increased, the rate of increase initially increased at a rapid rate, and showed that around 120 hours were sufficient curing time to complete hardening. 4. The average maximum temperature of Korea being around $30^{\circ}C$ from July to August, thus these months are ideal construction periods to increase the strehgth of lime soil mixtures. 5. Accelerated curing times equivalent to 28-day normal curing decreased in accordance with the increase of curing temperature, and showed shorter in lime soil mixtures than soil cement. 6. Accelerated curing times versus normal curing times are formed as a linear, its slope decreased in accordance with the increase of curing temperature, it may be expressed as follows: (1). $30^{\circ}C$ : t=2.63d-1.4(r=0.99) (2). $40^{\circ}C$ : t= 1.76d-0.8(r=0.97) (3). $50^{\circ}C$ : t=1.35d-3.2(r=0.94) (4). $60^{\circ}C$ : t=0.49d+1.8(r=0.91) in which t ; Accelerated curing time d ; Normal curing time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5915-5922
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• 2013

In this study, with the aim of improving the performance of shale to allow for its use as coarse aggregate for concrete, we coated shale aggregates with water repellents and polymers and evaluated their physical properties such as density, water absorption rate, wear rate, and stability depending on the coating method. In addition, the effects of the performance improvement were evaluated by assessing the properties of fresh concrete produced by varying the shale substitution ratio, as well as the compressive strength, flexural strength, and freeze-thaw resistance according to curing ages. The test results revealed that the absolute dry densities of all coated aggregates satisfied the standard density for coarse aggregates for concrete(>$2.50g/cm^3$),and the absorption rate of the shale aggregate coated with water repellent decreased by about 50% compared with that of uncoated shale. The wear rate of the polymer-coated shale decreased by up to 13.0% compared with that of uncoated shale. All coated aggregates satisfied the stability standard for coarse aggregates for concrete(${\leq}12$). The water repellent-induced performance improvement decreased the shale aggregates' slump by about 20~30mm compared with that of the uncoated shale aggregates, and the air content of the repellent-coated shale aggregate increased by up to 0.9% compared with that of the uncoated shale aggregate. The compressive strength of the polymer-coated shale aggregates at a curing age of 28 days was RS(F) 95.7% and BS(F) 90.0%, and the flexural strength was RS(F) 98.0 % and BS(F) 92.0% of the corresponding values of concretes produced using plain aggregates. Furthermore, the concrete using polymer-coated shale aggregates showed a dynamic modulus of elasticity of RS(F) 91% and BS(F) 88% after 300 freeze-thaw cycles, thus demonstrating improved freeze-thaw durability.

• Korean Journal of Plant Resources
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• v.27 no.1
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• pp.80-88
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• 2014

This study was carried out to understand the effect of sowing date on growth characteristics, flower duration of a total of 6 domestic rapeseed cultivars, "Sunmang", "Tammiyuchae", "Tamlayuchae", "Naehanyuchae", "Yongsanyuchae" and "Hallayuchae" with different sowing dates (25 Sept., 5 Oct., 15 Oct., 25 Oct., 5 Nov.) in Muan, Jeollanamdo, Republic of Korea. The results obtained were summarized as the follows: The number of seedling stand after overwintering was decreased in all 6 cultivars. It changed little until 5 Oct., and then showed continuously largely decrease as the sowing date being delayed. As the sowing date was being delayed, plant height was decreased while Silique length and thousand seed weight were increased. Seed yield in all 6 cultivars decreased almost linearly with late sowing date. In correlation analysis between the delaying sowing date and growth characteristics, it was inversely correlated with plant height ($r=-0.769^{**}$), No. of branches/plant ($r=-0.760^{**}$), No. of siliqua/panicle ($r=-0.631^{**}$) and seed yield ($r=-0.946^{**}$), while showed a positive correlation with silique length (r=0.635), seed diameter ($r=0.629^{**}$) and thousand grain weight ($r=0.422^*$). No. of seeds/silique and seed set percentage were not significantly correlated with the delaying sowing date. The flower duration was long in order of Sunmang, Tammiyuchae, Yongsanyuchae, Naehanyuchae, Hallayuchae and Tamlayuchae. Varietal variation of flowering date was larger with early sowing date than with delaying sowing date. The range of flower duration across all cultivars was from 1 day of Tamlayuchae to 14 days of Sunmang according to the sowing date, and the end flowering date was able to be extended from 2 to 9 days, compared to normal date of end flowering.

• Journal of Sericultural and Entomological Science
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• v.38 no.2
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• pp.160-167
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• 1996

The middle silk gland, that is a liquid silk thread gland consisting of silk protein, was taken out and a silk monofilament was made by drawing rapidly to approximately 3 times. In order to deteriorate the inter molecular hydrogen bonding force and to stretch in, the drawn silk filament was swoolen in boiling water. The results obtained are as follows ; The silk gland sample that just dried silk gland was occupied in crystalline region of silk-I type and random amorphous region. According to the examination of X-ray diffraction and thermal analysis, silk-II type crystal begins to appear partially in monofilament sample and spread to almost complet silk-II type crystal in 65.2% drawn sample. And, orientation of silk fibroin mlecule increased suddenly in early stage with a rise of drawing ratiofrom birefringence and density, and it was found that orientation of fibroin molecule was completed. As drawing ratio increases relation with time of hydrolysis, birefringence appeared almost fixed a tendency. Crystallization collapse by hydrolysis was not found in X-ray diffraction and thermal analysis. But, amorphous region began to flow by treated hydrolysis, that orientation of crystallization part was disturbed was supposed.

• Membrane Journal
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• v.19 no.4
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• pp.291-301
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• 2009

Double-layered polymer electrolyte membranes were prepared from two different sulfonated poly(aryl ether sulfone) copolymers by the two-step solution casting method for direct methanol fuel cells (DMFC). Sulfonation degrees were adjusted 10% (SPAES-10) and 50% (SPAES-50) by controlling monomer ratios, and the weight ratios of SPAES-10 copolymer were varied in the range of 5~20% to investigate the effect of thickness of coating layers on the membranes. Proton conducting layers were fabricated from SPAES-50 solutions of N-methyl-2-pyrrolidone (NMP) by a solution casting technique, and coating layers formed on the semiliquid surface of the conducting layer by pouring of SPAES-10-NMP solutions onto. It was found that double-layered polymer electrolyte membrane could significantly reduce the methanol crossover through the membrane and maintain high proton conductivities being comparable to single-layered SPAES-50 membrane. The maximum power density of membrane-electrolyte assembly (MEA) at the condition of $60^{\circ}C$ and 2 M methanol-air was $134.01\;mW/cm^2$ for the membrane prepared in the 5 wt-% of SPAES-10 copolymer, and it was corresponding to the 105.5% of the performance of the commercial Nafion 115 membrane.

• Journal of Environmental Impact Assessment
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• v.27 no.2
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• pp.203-214
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• 2018

The purpose of this study is to estimate the concentrated distribution area of nutria (Myocastor coypus) and potential suitable habitat and to provide useful data for the effective management direction setting. Based on the nationwide distribution data of nutria, the cross-validation value was applied to analyze the distribution density. As a result, the concentrated distribution areas thatrequired preferential elimination is found in 14 administrative areas including Busan Metropolitan City, Daegu Metropolitan City, 11 cities and counties in Gyeongsangnam-do and 1 county in Gyeongsangbuk-do. In the potential suitable habitat estimation using a MaxEnt (Maximum Entropy) model, the possibility of emergency was found in the Nakdong River middle and lower stream area and the Seomjin riverlower stream area and Gahwacheon River area. As for the contribution by variables of a model, it showed DEM, precipitation of driest month, min temperature of coldest month and distance from river had contribution from the highest order. In terms of the relation with the probability of appearance, the probability of emergence was higher than the threshold value in areas with less than 34m of altitude, with $-5.7^{\circ}C{\sim}-0.6^{\circ}C$ of min temperature of the coldest month, with 15-30mm of precipitation of the driest month and with less than 1,373m away from the river. Variables that Altitude, existence of water and wintertemperature affected settlement and expansion of nutria, considering the research results and the physiological and ecological characteristics of nutria. Therefore, it is necessary to reflect them as important variables in the future habitable area detection and expansion estimation modeling. It must be essential to distinguish the concentrated distribution area and the management area of invasive alien species such as nutria and to establish and apply a suitable management strategy to the management site for the permanent control. The results in this study can be used as useful data for a strategic management such as rapid management on the preferential management area and preemptive and preventive management on the possible spreading area.

• Journal of Conservation Science
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• v.32 no.4
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• pp.471-490
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• 2016

This study investigated provenance of raw materials and making technique of lime-based materials used in the tomb barriers of the Yesan Mokri tombs from Joseon dynasty on the basis of analysis to material characteristics and physical properties. In the barrier materials, dry density and porosity are the highest value ($1.82g/cm^3$) and the lowest value (25.20%) in the south wall of No. 1 tomb, respectively. Dry density and porosity are inversely proportional in all barrier materials, but unconfined compressive strength, which is the highest value of $182.36kg/cm^2$ in the No. 2 tomb, does not show an interrelation with porosity and density. Mineral components in the lime-soil mixtures of the tomb barrier are mainly quartz, feldspar, mica and calcite about 200 to $600{\mu}m$ size with yellowish brown matrix. Hydrotalcite and portlandite are detected in the lime mixture, and kaolinite in the soils. The lime materials of the tomb barrier occurred in large quantities weight loss and variable endothermic peaks caused by decarbonization reaction of $CaCO_3$ in the range from 600 to $800^{\circ}C$ in thermal analysis. Making temperature of lime for the tomb barrier is presumed approximately about $800^{\circ}C$ based on the occurrences, compositions and thermal analysis. The tomb barriers are revealed to very wide composition ranges of major elements and loss-on-ignition (22.5 to 33.6 wt.%) owing to mixture of the three materials (lime, sand and clay). It is interpreted that low quality construction technique was applied as the limes are very heterogeneous mixture with aggregates, and curing of the lime was poorly processed in the tomb barriers. Possible limestone sources are distributed in many areas around the Mokri site where limestone conformation and quarries for commercial production are found within Yesan and Hongseong areas. Therefore, we estimated that raw materials were possibly supplied from the local mines near the Mokri site.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.32-37
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• 2005

The procedure of soil sampling for on-farm quick test of soil nitrate is very important to improve practical application without weighing or drying soil. To improve application of test strip reflectometer as a quick on-farm analytical procedure for the estimation of soil nitrate concentration, three sampling methods such as gravimetric sampling (GS), particle density sampling (PDS) and bulk density sampling (BDS) for on-farm analytical procedure were investigated with twelve soils of 45 to $281mg\;kg^{-1}$ nitrate nitrogen concentration. The nitrate nitrogen concentrations measured from different soils were compared with two analytical methods, ion electrode method as a standard laboratory analysis (SLA) and test strip reflectometer at three moisture conditions, viz. air dried soil, 20 and 40% of maximum water holding capacity (MWHC). Nitrate nitrogen concentration measured by test strip reflectometer was significantly correlated with that of SLA, and the coefficients of variation (CV) were in the range of 3.5 to 10.9%. These CV values less than 10.9% were thought to be acceptable for the measurement of soil nitrate as an on-farm real time analytical procedure. The nitrate nitrogen concentration by BDS for test strip reflectometer as well as ion electrode method was more similar to that of SLA compared with those by GS and PDS especially in case of moist soils. This result suggests that the BDS is more useful than GS and PDS in case of on-farm analytical procedure of soil nitrate for moist soils. Further the practical measurement by BDS could be improved by substituting the bottle cap with a larger container.