• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.161-165
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• 2021

In general, SOFCs mainly use Ni-YSZ cermet, a mixture of Ni and YSZ, as an anode material, which is stable in a high-temperature reducing atmosphere. However, when SOFCs have operated at a high temperature for a long time, the structural change of Ni occurs and it results in the problem of reducing durability and efficiency. Accordingly, a development of a new anode material that can replace existing nickel and exhibits similar performance is in progress. In this study, SrTiO₃, which is a perovskite-based mixed conductor and one of the candidate materials, was used. In order to increase the electrical conduction properties, Y_0.08Sr_0.92Fe_0.3Ti_0.7O₃, doped with 0.08 mol of Y³⁺ in Sr-site and 0.03 mol of transition metal Fe³⁺ in Ti-site, was synthesized and its chemical diffusion coefficient and reaction constant were measured. Its electrical conductivity changes were also observed while changing the oxygen partial pressure at a constant temperature. The performance as a candidate electrode material was verified by predicting the defect area through the electrical conductivity pattern according to the oxygen partial pressure.

• Journal of Korean Elementary Science Education
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• v.40 no.2
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• pp.191-209
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• 2021

This study analyzed how characteristics of process-focused assessment are implemented in the distributed process-focused assessment examples in elementary school science education. To this end, through a review of previous studies, the analysis perspectives on the characteristics of the process-focused assessment were extracted into six categories. Using the analysis framework, it was described how process-focused assessment examples in elementary school science education developed by metropolitan office of education reflected the characteristics of process-focused assessment. As a result of the study, the characteristics of process-focused assessment were often formally reflected in sample materials. For example, there was a lack of skills on how to effectively integrate instruction and evaluation in practical terms. In many cases, feedback simply induced a recall of a learned concept or simply guides a related scientific concept. In some cases, the characteristics of process-focused assessment did not appear prominently in the sample materials. Also the developed sample materials were divided into the same type as the existing science and performance assessment questionnaire, a narrative·essay type, and a type similar to experimental workbook.

• Journal of the Korea Fashion and Costume Design Association
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• v.23 no.4
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• pp.105-116
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• 2021

Pillows are tools that humans have used for a long time to sleep or lie down and rest. It is bedding, and the oldest literature dealing with it is Volume 29 of 'GoryeoDogyeong', which describes embroidered pillows. The oldest relic is the queen's pillow (National Treasure No. 164) excavated from the tomb of King Muryeong, and is in the Gongju National Museum. This study attempts to investigate and reproduce the materials used in traditional pillows Yukgol pillows and pine nut pillows designs are based on literature and artifacts from the Joseon period to modern times. Regarding the research method, after reviewing literature and the relics of traditional pillows, the process of reproducing the traditional Yukgol pillow and the pine nut pillow production method were explained step by step. This study found the plain attitudes in the lives of people who used materials that could be easily gained from their daily lives in rural communities oriented to rice farming never recklessly threw out any piece of cloth or cotton and use it for pillow stuffing or pillow ends. Also, the sophisticated sense of aesthetics that you can see from the pine nut pillows, whose ends were made of remnants from making clothing are exquisitely similar to what was shown in patchwork previously. The biggest meaning of restoring traditional pillows was looking into traditional culture, particularly the ordinary people's living culture. It was very difficult because the researcher had to find materials that were difficult to obtain in this age, the making process was complex, and it took much time; however, it is significant in that the restoration of traditional pillows allows for the succession of tradition.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.3
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• pp.254-262
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• 2022

When treating partial edentulous patients, it is important to use an appropriate restorative materials. Inappropriate restorative materials can adversely affect the outcome of prosthetic restorations. Zirconia and dental metal, which are currently and widely used materials, have a higher elastic modulus than cortical bone, so when an external force is generated, a harmful force can be applied to the implant and the bone around the implant. Polyetherketoneketone (PEKK), a recently introduced material, has a elastic modulus similar to that of cortical bone, and has many advantages in terms of physical properties and biocompatibility. This case report describes that implant-supported fixed prosthetic treatment using PEKK was performed, and functional and esthetic satisfactory results were obtained.

• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.670-675
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• 2022

In the era of the 4th industrial revolution, everything is data-centric. The type and amount of data may be central, and new data may be required in special circumstances. As 3D printers are used in various fields, there are fields that are newly challenged. In particular, in the medical field, new attempts that have not been considered before are taking place. This paper is a study to enable research in fields that require physical properties of the human body. In the meantime, research using human organs has mainly used the materials made of silicon. We measure the physical properties of the human body from cadavers, apply these characteristics to develop new materials, and develop artificial organs with 3D printers. Using the artificial organs made in this way, you can practice surgery with a robot that removes kidney stones. In this paper, we would like to introduce a series of research processes to develop advanced materials similar to human organs.

• Journal of the Korea Institute of Building Construction
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• v.22 no.5
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• pp.451-462
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• 2022

The objective of the study is to establish a BIM modeling of precast concrete(PC) shear wall with various wall-to-base connections. The family library of PC shear wall was established in BIM program using component function in a IFC(Industry foundation classes) file format and SketchUp program. From the BIM program, the amounts of concrete, reinforcing bars and steel materials as well as the interference of arranged reinforcing bars can be accurately evaluated in the PC shear walls with spliced sleeves, bolt, or welding plate connection methods. Although the additional metallic materials such as steel plates, bolts, and nuts were used in the PC shear walls with welding plate connection method, their amounts of materials, economic efficiency, and environmental impact were similar to those with spliced sleeve connection. Consequently, the bolt or welding connection is a highly applicable method as wall-to-base connection of PC shear walls, and it was a more useful method than spliced sleeve method, particularly considering the constructability.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.397-405
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• 2022

Castor oil cake is widely used as a raw material for organic fertilizers (OF) in Korea. Compared to other fertilizer raw materials, it is highly dependent on imports. In terms of replacing raw materials, dehydrated food waste powder (FDP) and castor oil cake have similar nutritional content, and if 30% is replaced, about 20% of the raw material cost can be saved. However, few studies on the effects on crop growth and soil properties when organic fertilizer and dry food waste powder are mixed and applied to the soil have been reported. The effects of an organic fertilizer made by mixing the commercial available organic fertilizer with dehydrated food waste (OF + FDP) on soil properties and the growth of two types of leafy vegetables (lettuce and young radish) were evaluated and compared with the performance of OF. The fresh weights of lettuce and young radish were the highest with OF amendment and stood at 114.3 and 119.0 g·plant^-1, respectively. These were followed by OF + FDP amendment, which produced 103.1 and 109.6 g·plant^-1, respectively. Compared to the control, OF and OF + FDP increased the lettuce fresh weights by about 69% and 52%, respectively, while the fresh weights of the radish were increased by about 223% and 207%, respectively. The soil pH, EC, total carbon content, and organic matter content in OF and OF + FDP increased. The mixture of dehydrated food waste powder and organic fertilizers is expected to improve soil quality and facilitate stable production of crops and contribute to the substitution of imported organic fertilizer raw materials.

• Journal of the Korean Wood Science and Technology
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• v.30 no.1
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• pp.1-10
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• 2002

The aim of this research was to investigate the manufacturing possibility of the paper sludge-synthetic fiber-wood fiber composite. Three levels of the formulation of paper sludge, synthetic fiber and wood fiber (5:5:90, 15:15:70, 25:25:50), two types of adhesive (PMDI, urea-formaldehyde resin) and three levels of density(0.7, 0.8, 0.9) were designed. From the test result, composites with similar or better properties, when compared with commercial fiberboard, appeared to be possible by the addition of up to 30~50% paper sludge and synthetic fiber into wood fiber.

• Journal of Electrochemical Science and Technology
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• v.13 no.3
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• pp.390-397
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• 2022

The use of microwaves as the energy source for synthesis and sintering of ceramics offers substantial advantages compared to conventional gas-fired and electric resistance furnaces. Benefits include much shorter processing times and reaching the sintering temperature more quickly, resulting in superior final product quality. Most oxide ceramics poorly interact with microwave irradiation at low temperatures; thus, a more complex setup including a susceptor is needed, which makes the whole process very complicated. This investigation pursued a new approach, which enabled us to use microwave irradiation directly in poorly coupled oxides. In many solid-state electrochemical devices, the support is either metal or can be reduced to metal. Metal powders in the support can act as an internal susceptor and heat the entire cell. Then sufficient interaction of microwave irradiation and ceramic material can occur as the sample temperature increases. This microwave heating and exothermic reaction of oxidation of the support can sinter the ceramic very efficiently without any external susceptor. In this study, yttria stabilized zirconia (YSZ) and a Ni-YSZ cermet support were used as an example. The cermet was used as the support, and a YSZ electrolyte was coated and sintered directly using microwave irradiation without the use of any susceptor. The results were compared to a similar cell prepared using a conventional electric furnace. The leakage test and full cell power measurement results revealed a fully leak-free electrolyte. Scanning electron microscopy and density measurements show that microwave sintered samples have lower open porosity in the electrode support than conventional heat treatment. This technique offers an efficient way to directly use microwave irradiation to sinter thin film ceramics without a susceptor.

• Corrosion Science and Technology
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• v.22 no.1
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• pp.44-54
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• 2023

The rupture disk corrosion test (RDCT) method was recently developed to evaluate stress corrosion cracking (SCC) and was found to have great potential for the real-time detection of SCC initiation in a high temperature and pressure environment, simulating the primary water coolant of pressurized water reactors. However, it is difficult to directly measure the stress applied to a disk specimen, which is an essential factor in SCC initiation. In this work, finite element analysis (FEA) was performed using ABAQUS^TM to calculate the stress and deformation of a disk specimen. To determine the best mesh design for a thin disk specimen, hexahedron, hex-dominated, and tetrahedron models were used in FEA. All models revealed similar dome-shaped deformation behavior of the disk specimen. However, there was a considerable difference in stress distribution in the disk specimens. In the hex-dominated model, the applied stress was calculated to be the maximum at the dome center, whereas the stress was calculated to be the maximum at the dome edge in the hexahedron and tetrahedron models. From a comparison of the FEA results with deformation behavior and SCC location on the disk specimen after RDCT, the most proper FE model was found to be the tetrahedron model.