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저자 : 양혜원 ( Hye-won Yanga ) , 이창훈 ( Chang-hoon Leeb ) , 최병상 ( Byung-sang Choia )
발행기관 : 조선대학교 공학기술연구원
간행물 :
공학기술논문지
15권 1호
발행 연도 : 2022
페이지 : pp. 1-5 (5 pages)
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A large area (20 mm × 20 mm) of single-crystalline monolayer hBN without any microscopic defects (grain boundaries, twins, etc.) was successfully synthesized by MOCVD at little above the atmospheric pressure (770 torrs). It was primarily possible due to utilizing the large area and single-crystalline Cu as a substrate prepared by a contactless heat treatment method to prevent any heat-related stress to the specimen. With carefully controlled and well-organized experiments, it was found that a slow increase in temperature is more critical than long-time heat treatment. Secondly, heat treatment at 1083℃ after a quick temperature reduction from 1084℃ to 1083℃ within 1 min is another key condition to obtain a smooth surface for the growth of single-crystalline Cu without any defects. Microstructural studies of synthesized hBN were carried out by X-ray diffraction, optical microscopy, scanning electron microscopy, and transmission electron microscopy.
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저자 : 황선희 ( Sun Hee Hwang ) , 신동찬 ( Dong Chan Shin )
발행기관 : 조선대학교 공학기술연구원
간행물 :
공학기술논문지
15권 1호
발행 연도 : 2022
페이지 : pp. 7-12 (6 pages)
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The effect of voltage on Alq3 crystal growth in [C12mim][TFSI] was investigated. The additional voltage was applied through 1.0, 3.0, 5.0, 6.0, 8.0, 10.0 V. Cast iron and ITO were used as two electrodes. Microstructure analysis revealed the rod shape of Alq3. When the applied voltage increases, the population of rod shape phases increases. The XRD analysis showed that the initial phase transited to γ and finally δ phases. The conventional growth methods of the vapor phase and the solution method need a high temperature of over 300 ℃, while the study's new approaches can lower the heat-treatment temperature to 100 ℃. The phase transition was promoted faster when the applied voltage increased from 0 to 10.0 V. The additional voltage is thought to play a vital role in promoting the phase transition due to lowering the activation energy of nucleation. The phase and shape of OLED materials affect the performance of the OLED device. One can obtain various shapes and phases of Alq3 at a low temperature of 100 ℃, which is a promising technique for OLED material manufacturing. The results also suggest a new academic point of view to understand the nucleation behavior of OLED materials with artificially applied charges.
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저자 : 문은아 ( Eun-ah Moon ) , 이나원 ( Na-won Lee )
발행기관 : 조선대학교 공학기술연구원
간행물 :
공학기술논문지
15권 1호
발행 연도 : 2022
페이지 : pp. 13-18 (6 pages)
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A high step-up gain DC-DC converter with a single switch is introduced in this paper. The introduced DC-DC converter can provide the common ground between renewable energy sources and the negative side of the output load. The extension of an introduced DC-DC converter is also presented to provide the high voltage gain. In addition, the voltage stresses across the devices of the introduced DC-DC converter are still low. The theoretical analysis and a comparison considering other converters previously published in the literature are presented in the paper. In order to validate the introduced DC-DC converter characteristic, a simulation and prototype have been built with a power rating of 450 W.
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저자 : 김근영 ( Keun-young Kim ) , 장명훈 ( Myunghoun Jang )
발행기관 : 조선대학교 공학기술연구원
간행물 :
공학기술논문지
15권 1호
발행 연도 : 2022
페이지 : pp. 19-25 (7 pages)
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The recent dormitory construction has been carried out in a build-transfer-release (BTL) method in which a special purpose company (SPC) builds dormitories and rents them for a certain period for financial reasons of universities. J University has several dormitories managed and operated by itself and entrusted to the SPC. This study aims to provide basic data that can be used for future dormitory remodeling or new building plans through the comparative analysis results of two types of facility satisfaction surveys with different dormitory management subjects. As a result of the satisfaction survey on dormitory students, despite the difference in the construction time of the dormitories, the survey confirmed that the evaluation of the dormitory was generally satisfactory and there was no significant difference.
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저자 : 최사랑 ( Sa-rang Choi ) , 김만종 ( Man-jong Kim )
발행기관 : 조선대학교 공학기술연구원
간행물 :
공학기술논문지
15권 1호
발행 연도 : 2022
페이지 : pp. 27-32 (6 pages)
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This study confirmed the anti-inflammatory effects of Glycyrrhiza glabra L. complex extracts (Glycyrrhiza glabra L. and Morus alba L.) by the complex ratio of Glycyrrhiza glabra L. and Morus alba L. extract. Cell viability was assessed using RAW 264.7 cells by MTT assay. The Glycyrrhiza glabra L. complex extract was measured through changes in the levels of prostaglandin E2 (PGE2), nitric oxide (NO), inflammatory cytokine (i.e., IL-1beta, IL-6, and TNF-alpha), COX-2, and iNOS in LPS-induced RAW 264.7 cells. All test results were analyzed by an ELISA reader, western blot analysis, and Luminex. Compared with those in the control group, all complex ratio extracts were not toxic below a concentration of 100 ㎍/㎖. In addition, the complex ratio extract treatments significantly reduced the productions of NO, PGE2, and cytokine and significantly inhibited the mRNA expression of COX-2 and iNOS in LPS-induced RAW 264.7 cells. The results indicate that Glycyrrhiza glabra L. complex extracts prevented and alleviated inflammatory indications. Thus, Glycyrrhiza glabra L. complex extracts may be developed as a functional option material for feeding to improve diseases caused by inflammatory mediators.
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