http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Laser powder bed fusion 공정으로 제조된 오스테나이트계 316L 스테인레스 강의 고온 산화 거동
황유진,위동열,김규식,이기안,Hwang, Yu-Jin,Wi, Dong-Yeol,Kim, Kyu-Sik,Lee, Kee-Ahn 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.2
In this study, the high-temperature oxidation properties of austenitic 316L stainless steel manufactured by laser powder bed fusion (LPBF) is investigated and compared with conventional 316L manufactured by hot rolling (HR). The initial microstructure of LPBF-SS316L exhibits a molten pool ~100 ㎛ in size and grains grown along the building direction. Isotropic grains (~35 ㎛) are detected in the HR-SS316L. In high-temperature oxidation tests performed at 700℃ and 900℃, LPBF-SS316L demonstrates slightly superior high-temperature oxidation resistance compared to HR-SS316L. After the initial oxidation at 700℃, shown as an increase in weight, almost no further oxidation is observed for both materials. At 900℃, the oxidation weight displays a parabolic trend and both materials exhibit similar behavior. However, at 1100℃, LPBF-SS316L oxidizes in a parabolic manner, but HR-SS316L shows a breakaway oxidation behavior. The oxide layers of LPBF-SS316L and HR-SS316L are mainly composed of Cr<sub>2</sub>O<sub>3</sub>, Fe-based oxides, and spinel phases. In LPBF-SS316L, a uniform Cr depletion region is observed, whereas a Cr depletion region appears at the grain boundary in HR-SS316L. It is evident from the results that the microstructure and the high-temperature oxidation characteristics and behavior are related.
황유진,조인호,임주환,임헌송,Hwang Yu-Jin,Cho In-Ho,Lim Ju-Hwan,Lim Heon-Song 대한치과보철학회 2005 대한치과보철학회지 Vol.43 No.1
Statement of problem. Among the physical properties of adhesion luting cement, the aspect that requires the most important factor is the degree of solubility and water sorption. Dissolution or an inadequate due to excessive water sorption inside the oral cavity compromises the while concurrently increasing the susceptibility to secondary dental caries. Susceptibility to dissolution and difficulty of removing remnant cement from the gingival sulcus have hindered the use of dental resin cement in the clinical practice, but the improved characteristics of newer generation resin cements have interest in and enabled resin cements to be widely used in adhesion of fixed prosthesis, such as laminate veneers and all-ceramic crowns. Purpose. The purpose of this study is to compare and analyze the degrees of solubility and water sorption of a variety of resin cements widely used for clinical purposes with different curing methods. Material and methods. Self-curing resin cements, $Avanto^{(R)}$, $C&B^{TM}$ CEMENT and Superbond C&B cements comprised group 1, 2 and 3. The dual-curing resin cements $Panavian^{TM}$ F, $Calibra^{(R)}$ and $Variolink^{(R)}$ II were divided into groups 4, 5, and 6, respectively. The investigation was carried out using disc-shaped specimens as specified by ANSI/ADA Specification No. 27. The degree of water sorption, water solubility and lactic acid solubility of each test group was analyzed statistically leading to the following conclusion. Results. The degree of water sorption was shown to increase in the following order : group 6, 5, 4, 2, 1 and 3. There were significant differences between the water sorption of each group. Results of the degree of water solubility were shown to increase in the following order : group 6, 5, 4, 2, 1 and 3. Statistically significant differences were found between each group, with the exception of groups 1 and 3. Finally, the degree of lactic acid solubility was found to increase in the following order : group 6,5,4,2,3 and 1. Significant differences were found between each group. In general dual-curing resin cements displayed substantially lower values than self-curing resin cements with regard to water sorption, water solubility, and lactic acid solubility. Conclusions. From the results of this study, dual-curing resin cements show a significantly lower degree of water sorption and solubility than their self-curing counterparts. Clinically, when selecting resin cements, the product with a lower degree of water sorption and solubility are preferred. The results of this study indicate that the use-of dual-curing resin cements is preferable to self-curing cements.
Atmospheric plasma spray 공정으로 제조된 Y<sub>2</sub>O<sub>3</sub> 코팅층의 미세조직 및 기계적 특성에 미치는 분사 각도의 영향
황유진,김경욱,이호영,권식철,이기안,Hwang, Yu-Jin,Kim, Kyoung-Wook,Lee, Ho-Young,Kwon, Sik-Chol,Lee, Kee Ahn 한국분말재료학회 (*구 분말야금학회) 2021 한국분말재료학회지 (KPMI) Vol.28 No.4
The effects of different spray angles (90°, 85°, 80°) on the microstructure and mechanical properties of a Y<sub>2</sub>O<sub>3</sub> coating layer prepared using the atmospheric plasma spray (APS) process were studied. The powders employed in this study had a spherical shape and included a cubic Y<sub>2</sub>O<sub>3</sub> phase. The APS coating layer exhibited the same phase as the powders. Thickness values of the coating layers were 90°: 203.7 ± 8.5 ㎛, 85°: 196.4 ± 9.6 ㎛, and 80°: 208.8 ± 10.2 ㎛, and it was confirmed that the effect of the spray angle on the thickness was insignificant. The porosities were measured as 90°: 3.9 ± 0.85%, 85°: 11.4 ± 2.3%, and 80°: 12.7 ± 0.5%, and the surface roughness values were 90°: 5.9 ± 0.3 ㎛, 85°: 8.5 ± 1.1 ㎛, and 80°: 8.5 ± 0.4 ㎛. As the spray angle decreased, the porosity increased, but the surface roughness did not show a significant difference. Vickers hardness measurements revealed values of 90°: 369.2 ± 22.3, 85°: 315.8 ± 31.4, and 80°: 267.1 ± 45.1 HV. It was found that under the condition of a 90° angle with the lowest porosity exhibited the best hardness value. Based on the aforementioned results, an improved method for the APS Y<sub>2</sub>O<sub>3</sub> coating layer was also discussed.
주거용 건물을 위한 냉난방 및 급탕 통합 히트펌프 시스템의 에너지 절감 가능성 분석
황유진(Hwang, Yu-Jin),정재원(Jeong, Jae-Weon) 한국건축친환경설비학회 2020 한국건축친환경설비학회 논문집 Vol.14 No.5
The present study aims to evaluate energy saving potential of heat pump system functioning as cooling, heating and hot water supply applicable for residential buildings. To analyze the advantage of integrating heating and cooling, existing mono function air-source heat pump and radiant floor heating system were set to the reference case. The model building was established in TRNSYS 18, and integrated energy simulation in annual was conducted with all system model equations in EES program. The results show that proposed heat pump system reduced 11-12.5% energy consumption in simulation cases, compared to the reference system.