• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.240-245
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• 2015

The monitoring of soil fertility changes in orchard is very important for agricultural sustainability. Field monitoring was performed to evaluate the soil chemical properties of 140 orchard (23 sites for sandy loam, 88 sites for loam, 28 sites for silt loam, and 1 site for loamy fine sand) in Gyeongnam province every 4 years from 2002 to 2014. Soil chemical properties such as pH, electrical conductivity, amount of organic matter (OM), available phosphate ($P_2O_5$), lime requirement (LR), exchangeable potassium (K), calcium (Ca), magnesium (Mg), and sodium were analyzed. The amount of OM, exchangeable K, Ca, and Mg were significantly increased as cultivation year increases. The frequency distribution within optimum range of subsoil chemical properties in 2014 was 34.3% for pH, 35.0% for OM, 17.1% for available $P_2O_5$, 22.9% for exchangeable K, 15.7% for exchangeable Ca, and 22.1% for exchangeable Mg. In addition, the available $P_2O_5$ and exchangeable calcium were excess level with portions of 69.3% and 48.6%, respectively. The soil chemical properties in the topsoil and subsoil showed that soil pH was significantly higher in sandy loam soil than those from the loam and silt loam soils. The OM, exchangeable K, Mg, and LR of loam soil were higher than those from the sandy loam soil. These results indicated that a balanced management of soil chemical properties as affected by soil texture can improve the amount of fertilizer applied for sustainable agriculture in orchard field.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.793-797
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• 2010

The investigations were conducted to improve the physical properties by analyzing physico-chemical properties on the different soil families of textures at 20 upland fields located in the parts of Gyengsangbuk-do area. Soil physico-chemical properties were analyzed for bulk density, hardness, porosity, moisture, pH, EC and organic mater by soil depth on the different soil families of textures. Bulk density distributions were higher than 1.2 Mg $m^{-3}$ in the optimum range. Hardness distributions were lower than 20 mm in the optimum range. Therefore, the physical properties of upland soil was deteriorated. Correlation coefficient of bulk density with hardness and organic mater were higher significantly, that was positive and negative, respectively. The soil hardness had the greatest distribution degree to the crop yield and bulk density and organic matter followed. Conclusively, To improve the physical properties of upland soil was more effective to fertilizing organic matter than other ways.

• Journal of Mushroom
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• v.16 no.4
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• pp.250-256
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• 2018

The windrow turner, widely used for outdoor fermentation of mushrooms in Europe, has been improved by using rice straw instead of wheat straw in accordance with Korea's actual situation. It was compared with conventional excavator work, and the results were as follows. Agitation performance was $81m^3/hr$, which was 2.8 times higher than $28.6m^3/hr$ of excavator. As a result of the temperature distribution in the pile at the end of the fermentation stage, it was found that the temperature at the lower part of the pile was $5^{\circ}C$ higher than that of conventional pile. This was more favorable for aerobic fermentation. Meanwhile, ash ratio of prototype ($30.9{\pm}1.1%$) was higher than that of control $28.4{\pm}1.6%$. In the case of prototype turner agitation, the yield of mushroom cultivation was $880kg/66m^2$, that was 22.9% higher than the conventional control yield of $716kg/66m^2$.

• Journal of Conservation Science
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• v.37 no.5
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• pp.545-556
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• 2021

In this study, we aimed to elucidate the materialistic characteristics of 11 pieces of earthenware belonging to the Neolithic and Bronze Age excavated from Jeongseon Auraji, South Korea. As a result, the chemical composition of earthenwares belonging to the early Bronze Age was distributed in the intermediate area between the Neolithic and Bronze Age earthenwares, but no significant difference was confirmed based on their manufacturing period. Upon comparison, the earthenwares excavated from Jeongseon Auraji site were found to comprise less acidic components than those excavated from Yeongdong, and are characterized by the alkaline components depending on the excavated site. In the rare earth elements distribution pattern, all the analyzed earthenwares exhibited similar pattern, confirming that the raw materials present in the clay were the same. As a result of microstructure analysis, the clay particles and voids were found to be irregularly distributed in the analyzed earthenwares. Neolithic earthenwares exhibited many irregular voids, and an arrangement of aluminosilicate, including feldspar, was observed along with the clay substrate. Furthermore, we confirmed that the empty space in early Bronze Age earthenwares was filled with fine particles and cube crystals. Moreover, the main mineral phase of earthenwares excavated from Jeongseon Auraji exhibited similar composition, and therefore, there was no significant difference in the firing temperature of these earthenwares. The firing temperature of the earthenwares ranged from 750 to 850℃.

• Journal of the Korean Applied Science and Technology
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• v.38 no.2
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• pp.476-487
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• 2021

To prepare acrylic resin coatings containing 70% of solids, we used n-butyl methacrylate(BMA), methyl methacrylate(MMA), 2-hydroxyethyl methacrylate(2-HEMA), and acetoacetoxyethyl acrylate(AAEA), caprolactone acrylate(CLA) as raw materials, the glass transition temperature(T_g) of acrylic copolymer was adjusted around 50 ℃. The viscosity and molecular weight of the acrylic resins was increased with increasing OH values. Di-tert-amyl peroxide was found to be the suitable initiator to get high-solids acrylic resins. The optimum reaction conditions found in the study are 5 wt% of initiator, 4 wt% of chain transfer agent, 4 hrs of dropping time, and 140 ℃ of reaction temperature. The structure of the synthesized resins were characterized by FT-IR and ¹H-NMR spectroscopy. Number average molecular weight of 1900~2600 and molecular wight distribution of 1.4~2.1 were obtained. Crosslinked acrylic urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate trimer(Desmodur N-3300), the equivalent ratio of NCO/OH was 1.2/1.0. The physical properties from the following studies were carried out: viscosity(Zahn cup #2), adhesion, drying time, pot-life, pensil hardness, and 60° specular gloss. Various properties of the acrylic urethane clear coatings were also evaluated on the coating specimens. Adhesion property to a substrate, drying time, pot-life, pencil hardness, and 60° specular gloss of prepared paint showed quite good properties. Futhermore, prepared paint containing 10% of CLA showed quite good properties for adhesion, low viscosity and high hardness.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.185-190
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• 2021

Cement has been used as a main material in the modern construction industry. However, it has been pointed out as a main cause of global warming due to carbon dioxide generated during manufactured. Recently, research that replacing cement substitute to industrial by-products such as Blast Furnace Slag which is by-producted in steelworks. When Blast Furnace Slag is used as a cement substitute, it shows a problem of lower initial strength, which is caused by glassy membrane on the particle surface. In this study, we used Electrolysis Alkaline Aqueous to improve the usability and problem of lower initial strength. As a result of the experiment, cement matrix using Blast Furnace Slag and Alkaline Aqueous showed initial strength and hydrate product were developed than that using general mixing water. Also, as a result of porosity analysis, It was confirmed that cement matrix using Alkaline Aqueous and Blast Furnace Slag has a tighter structure in internal porosity and porosity distribution than using general mixing water.

• Journal of fish pathology
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• v.31 no.2
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• pp.115-122
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• 2018

The Houttuynia cordata has been utilized for various beneficial purposes in humans mainly because of its potent antioxidant principle quercitrin present in this plant. This study examines the possibility of producing a functional sea food commodity containing active principle quercitrin by feeding H. cordata for a extended period. Spotted sea bass (Lateolabrax maculatus) were fed a diet containing H. cordata at 0.1-1.0% levels for 1 month and tissue concentrations of quercitrin were analyzed in serum, hepatopancreas and muscle. It was observed that quercitrin was found in the ranking order of hepatopancreas>muscle>serum. After a bolus administration of quercitrin (20 mg/kg, oral) to spotted sea bass and Nile tilapia (Oreochromis niloticus), idential rank order was observed after 48 hr. In contrast, the order was liver>serum>muscle in rat and mice, indicating that higher quercitrin distribution occurs to the muscle in fishes compared with in mammals tested. High residue concentration of qeurcitrin in the edible tissue can be an advantageous property in terms of functional food production. High level H. cordata extract inclusion of 1.0% seems to have detrimental effects in spotted sea bass leading to growth retardation and hepatic damage. It was concluded that incorporation of H. cordata extract into diet can be a way of producing healthy foods. However the level of active extract needs fine tuning to avoid toxicity to fishes.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.1
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• pp.29-33
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• 2019

With shrinking form factor and improving performance of electronic packages, high input/output (I/O) density is considered as an important factor. Fan out wafer-level packaging (FO-WLP) has been paid great attention as an alternative. However, FO-WLP is vulnerable to warpage during its manufacturing process. Minimizing warpage is essential for controlling production yield, and in turn, package reliability. While many studies investigated the effect of process and design parameters on warpage using finite element analysis, they did not take uncertainty into consideration. As parameters, including material properties, chip positions, have uncertainty from the point of manufacturing view, the uncertainty should be considered to reduce the gap between the results from the field and the finite element analysis. This paper focuses on the effect of uncertainty of Young's modulus of chip on fan-out wafer level packaging warpage using finite element analysis. It is assumed that Young's modulus of each chip follows the normal distribution. Simulation results show that the uncertainty of Young's modulus affects the maximum von Mises stress. As a result, it is necessary to control the uncertainty of Young's modulus of silicon chip since the maximum von Mises stress is a parameter related to the package reliability.

• Journal of Wetlands Research
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• v.23 no.2
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• pp.107-115
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• 2021

In order to analyze wave propagation, tidal current, and sediment transport in the vicinity of the Gaeya open channel, it was classified into before(CASE1W) and after(CASE2W) installation of various artificial structures, and the calculation results for CASE1W and CASE2W were compared. For wave propagation, the results of incident and reflected waves were derived using the SWAN numerical model, and the tidal current velocity results were derived using the FLOW2DH numerical model for tidal current. The results of the SWAN numerical model and the FLOW2DH numerical model became the input conditions for the SEDTRAN numerical model that predicts sediment transport, and the maximum bed shear stress and suspended sediment concentration distribution near the Gaeya open channel were calculated through the SEDTRAN numerical model. As a result of the calculation of the SWAN numerical model, the wave height of CASE2W was increased by 40~50 % compared to CASE1W because the incident wave was diffracted and superimposed and the reflected wave was generated by about 7 km long northen jetty. As a result of the calculation of the FLOW2DH numerical model, According to the northen breakwater, the northen jetty and Geumrando, CASE2W was calculated 10~30 % faster than CASE1W in the tidal current of the Gaeya open channel. As a result of the calculation of the SEDTRAN numerical model, the section where the maximum bed shear stress is 1.0 N/m² or more and the suspended concentration is 80mg/L or more was widely distributed in the Gaeya open channel from the marine environment by the complex wave field(incident wave, reflected wave and tidal wave) and the installation of various artificial structures. it is believed that a sedimentation phenomenon occurred in the Gaeya open channel.

• Korean Journal of Cognitive Science
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• v.31 no.4
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• pp.103-136
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• 2020

This study compares the parafovea preview effect of adolescent group and adult group with different ages using eye tracking experiment. Also, this study confirms that the starting point parameter of the one boundary diffusion model can explain the data obtained through eye tracking experiments. In two experiments, parafoveal information processing was examined using the boundary technique. In Experiment 1, reading times were compared between the conditions given high frequency words preview versus masking preview. In Experiment 2, the condition in which low frequency words were given to parafovea preview information and the condition in which parafovea preview was masked were compared. We found that both the adolescent group and the adult group showed a parafovea preview effect. Also, first fixation, single fixation, and gaze duration of the two groups were different based on the word property shown in the parafovea. The first fixation data obtained in the two experiments were divided into quantiles and fitted into one boundary diffusion model. From the results, we argue that the parafovea preview information processing in the reading was described as the starting point parameter of the one boundary diffusion model.