• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.4
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• pp.293-304
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• 2022

In this study, to analyze the effect of buildings on the image co-registration performance, co-registration results are compared according to the presence or absence of matching points extracted from buildings. To remove the matching points extracted from buildings, a building mask generated by extracting building objects from the digital topographic map was used. In addition, matching points extraction performance and image co-registration accuracy were analyzed according to the magnitude of the convergence angle. Image co-registration results were compared by applying the affine and piecewise linear transformation models, respectively. According to the experimental results, the affine transformation model showed an overall improvement in accuracy after removing the matching points extracted from buildings. On the other hand, the piecewise linear transformation model improved the accuracy at the checkpoints including the surrounding buildings, but the accuracy improvement was not significant at checkpoints in the flat area without the existence of buildings. In addition, when the piecewise linear transformation model was applied, stable accuracy of less than 2 pixels was derived from images with a convergence angle of 20° or less.

• Journal of the Korean Ceramic Society
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• v.30 no.10
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• pp.803-810
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• 1993

PbxZr0.4Ti0.6O3 thin films were prepared by reactive co-sputtering and annealed by RTA(Rapid Thermal Annealing) process. Effect of Pb content in PbxZr0.4Ti0.6O3 films on the phase transformation was intensively studied. It has been found out that depending on the Pb content as well as RTA temperature, crystal structure of PbxZr0.4Ti0.6O3 films change greatly. It turned out that transformation temperature for perovskite can be lowered and the width of transition temperature region was reduced by increasing Pb content in the film. And the lattice was expanded with increasing Pb content. With increasing RTA temperature, as-deposited phase was transformed into perovskite through three different transformation paths depending on Pb content. It was confirmed that activation energies for nucleation of perovskite structure are much larger than those of its growth.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.248-250
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• 2006

The study on a surface transformation hardening of a rod-shaped SM45C carbon steel is carried out by using CW Nd:YAG laser. Conventionally, $CO_2$ laser has been usually used as a laser source for a transformation hardening. however, it is needed to an additional absorbent coating like a colloidal graphite owing to a lower absorbtion rate. On the other hand, no cost and post-removal process of coating is required to Nd:YAG laser, due to a higher absorbtion rate relatively. Moreover, there is a merit which is capable of building up the more flexible processing system resulted from a beam delivery through a optical fiber. In this study, we were going to recognize characteristics of a transformation hardening using a optic head with a gaussian beam distribution.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.1
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• pp.12-23
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• 1995

In this a set of constitutive equation relevant to the analysis of thermo-elasto-plastic materials with phase transformation during quenching process was presented on the basis of continuum thermo-dynamic. In calculating the transient thermal stresses, temperature between coolant and specimen(SM45C) surface was determined from the heat transfer coefficient. A calculation was made for specimen with 40mm in diameter quenched in coolant from $820^{\circ}C$ and the results are as follow. Stresses at starting point of transformation always show the maximum tensile value. Reverse of stresses takes place after completion of transformation of inner part at specimen.

• International Journal of Korean Welding Society
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• v.3 no.2
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• pp.46-52
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• 2003

The refinement of microstructure and phase transformation near the interface of pure copper/carbon steel dissimilar metals joints with various friction welding parameters have been studied in this paper. The microstructure of copper and carbon steel joints were changed to be a finer grain compared to those of the base metals due to the frictional heat and plastic deformation. The microstructure of copper side experienced wide range of deformed region from the weld interface and divided into very fine equaxied grains and elongated grains. Especially, the microstructures near the interface on carbon steel were transformed from ferrite and pearlite dual structure to fine ferrite, grain boundary pearlite and martensite due to the welding thermal cycle and rapid cooling rate after welding. These microstructures were varied with each friction welding parameters. The recrystallization on copper side is reason for softening in copper side and martensite transformation could explain the remarkable hardening region in carbon steel side.

• Journal of Plant Biotechnology
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• v.29 no.2
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• pp.85-92
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• 2002

This study has been focused on improving transformation efficiency of rice using Agrobacterium tumefaciens. We have demonstrated the effect of this system when the GPAT gene related to the cold-resistance was transferred by Agrobacterium tumefaciens in rice. Transformation conditions were modified using intron $\beta$-glucuronidase (GUS) expression as a reporter gene in the rice. In this study, mature seed-derived calli of rice (Oruza sativa L. cv. Dongjin) were pre-cultured for 3 days and then infected with Agrobacterium. When this infected calli were cultured in the dark for 10 days on co-cu]lure medium containing 50 mg/L of CaCl$_2$, 30 mg/L of acetosyringone, 2 mg/L of 2,4-D, 120 mg/L of betaine, high GUS expression was observed. In the present transformation system, the efficiency of transformation of GPAT gene was about 54%. Stable integration of GPAT gene into chromosomal DNA was proven by southern blot analysis of genomic DNA isolated from T$_{0}$ progenies. The progenies (T1 generation) derived from primary transformant of 5 lines were segregated with a 3 (resistant) : 1 (sensitive ratio) in medium containing hygromycin. This high frequency transformation system can be used as a useful tool in transformation of another monocotyledon.n.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.311-313
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• 2004

WC-12-17%Co powders with nano- and micro-structures were deposited by cold spray process using nitrogen and helium gases. The results show that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition as expected. It is also observed that nano-sized WC in the feedstock powder is maintained in the cold spray deposition. It is demonstrated that it is possible to fabricate the nano-structured WC-Co coating with low porosity and very high hardness (-2050 HV) by cold spray deposition with reasonable powder preheating.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2004.10a
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• pp.100-100
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• 2004

• Journal of Digital Convergence
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• v.19 no.11
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• pp.463-470
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• 2021

Due to natural and human factors, dunhuang frescoes in China have gradually degenerated. China has conducted digital transformation of frescoes since 1990. However, it requires expensive research costs. Most of the visitors passively accept transformation contents and lack subjective participation. The paper focuses on produces a prototype of Dunhuang frescoes on the CoSpaces EDU. It was implemented as a metaverse through procedures such as transforming the cave into 3D, mapping images to the cave model and developing CoBlocks. The research puts forward a more specific methodology without expensive costs of development. The paper makes it easier to realize the immersive and interactive virtual Dunhuang frescoes world, to improve the tourism contents and educational effect. This research carries on the statistics to the product result which develops according to the user experience of 100 different ages, has obtained the good feedback. The research results need to be improved is to strengthen the processing of graphic details. Therefore, Optimization and improvement of the result will be carried out in the future research.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.6
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• pp.270-275
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• 2021

ZnO was synthesized according to the transformation behavior and crystallization conditions of Zn-intermediate obtained by zinc sulfate as a precursor and NaOH, Na₂CO₃ as a alkali agents. For ZnO crystallization, Zn₄(OH)₆SO₄·H₂O and Zn₅(OH)₆(CO₃)₂·H₂O as a Zn-intermediate were calcined at 400℃ and 800℃ for 1 h, respectively, based on decomposition temperature from TGA. Zn₄(OH)₆SO₄·H₂O was confirmed to have mixed Zn₄(OH)₆SO₄·H₂O and ZnO at 400℃, and was completely thermally decomposed at 800℃ to form ZnO phase. The prepared Zn₅(OH)₆(CO₃)₂·H₂O as a Zn-intermediate by the reaction with Na₂CO₃ was transformed to a complete ZnO crystallization over 400℃. Nano-sized ZnO can be synthesized at a relatively lower calcination temperature through the reaction with Na₂CO₃.