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Bae Yumi,Zeb Alam,Choi Ho-Ik,류정수,Gul Maleeha,Noh Ha-Yeon,Cho Junho,Gil Junkyung,Shah Fawad Ali,Chang Sun-Young,Bae Ok-Nam,Kim Jin-Ki 한국약제학회 2024 Journal of Pharmaceutical Investigation Vol.54 No.5
Purpose Dexamethasone palmitate (DXPL) is a lipophilic derivative of dexamethasone (DXM) used to overcome the low drug-loading capacity and immediate release characteristics of DXM from nanoparticles. In this study, we investigated the potential of DXPL-loaded solid lipid nanoparticles (DXPL-SLNs) to increase drug encapsulation efficiency, prolong drug release, and alleviate skin inflammation. Methods DXPL-SLNs were prepared using the nano-emulsion template technique with trilaurin as a lipid matrix and Tween 20, Span 20, and Brij 58 as a surfactant mixture. The physicochemical properties of DXPL-SLNs were examined in terms of particle size, polydispersity index, zeta potential, encapsulation efficiency, loading capacity, morphology, and crystalline behavior. The in vitro release profile of DXM from the DXPL-SLNs incubated in mouse plasma was assessed using a plasma conversion assay. In vivo anti-inflammatory effects of topically applied DXPL-SLNs were evaluated in mice with 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced ear edema. Results The optimized DXPL-SLNs (DXPL/trilaurin/Tween 20/Span 20/Brij 58:4/2/2/0.2/4, w/w ratio, respectively) displayed a mean particle size of 182.8 ± 2.7 nm with a very high drug loading capacity of 30.4%. DXPL-SLNs showed substantially prolonged drug release in mouse plasma compared to DXPL solution. Furthermore, DXPL-SLNs showed enhanced anti-inflammatory effects by efficiently reducing TPA-induced ear edema. Conclusion These findings suggest that DXPL-SLNs have great potential as anti-inflammatory therapeutics against acute skin inflammation.
Accelerated wear testing of polyurethane hydraulic seal
Bae, Junho,Chung, Koo-Hyun Applied Science Publishers 2017 POLYMER TESTING -LONDON- Vol.63 No.-
<P><B>Abstract</B></P> <P>The wear characteristics of a polyurethane (PU) hydraulic seal were investigated using a hydraulic seal tester and a pin-on-plate reciprocating tribo-tester, and the results were compared to field data with the aim of developing an accelerated wear test method for hydraulic seals. Tests using a hydraulic seal tester and a pin-on-plate reciprocating tribo-tester were found to reproduce abrasive wear of PU from the field. However, a significant compression set was observed from the test using the hydraulic seal tester. Motivated by the occurrence of abrasive wear from the field, the discolored lubricant and the lubricant with alumina particles were further used for testing using the pin-on-plate reciprocating tribo-tester. The height decrease data of the sealing surface showed that the wear was accelerated by factors of 2.1–3.4 using these degraded lubricants. The outcomes of this work are expected to aid in the design of reliable accelerated life testing for hydraulic seals.</P>
CNG 압력용기의 제조 공정 개선을 통한 다이 수명 향상에 관한 연구
배준호(Junho Bae),이현우(Hyunwoo Lee),김문생(Moonsaeng Kim),김철(Chul Kim) 한국자동차공학회 2012 한국자동차공학회 지부 학술대회 논문집 Vol.2012 No.5-1
Deep drawing and ironing (D.D.I.) process using the horizontal press with high-capacity is used for CNG (Compressed natural gas) pressure vessel. And, some process variables of D.D.I process have been determined by experiences of the workers, and wear of the dies is necessary to be improved for high-quality and low-cost in manufacturing the pressure vessel. In this study, the process variables (Draw ratio, clearance, distance between dies, radius of rounding of drawing die, angle of ironing die) for process stability and improvement of die life are chosen on the basis of relevant previous studies and of experiences of the workers. Draw ratio and clearance at each draw step are determined in forming limit without tearing by FEA. And, distances between dies, radius of rounding of drawing die, angle of ironing die are optimized by DOE method. The results of the optimal process variables are compared with those of the existing D.D.I process for verifying effectiveness.
금속 볼 밸브의 볼·시트 마멸 특성에 관한 실험적 연구
배준호(Junho Bae),정구현(Koo-Hyun Chung) 한국트라이볼로지학회 2016 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.32 No.1
The wear characteristics of metal ball and seat in a metal-seated ball valve significantly affect the performances such as leakage and valve torque. In this work, the wear characteristics of metal ball and seat are experimentally investigated. A stainless steel ball and seat with a high corrosion-resistant coating are prepared and a component level test was performed. The hardness and surface roughness of specimens cut from the metal ball and seat are measured before and after the test using a micro-Vickers hardness tester and confocal microscopy, respectively. In order to assess the wear characteristics, the surfaces of the specimens are carefully examined after the test. The confocal microscope data show that the surface roughness values of both the ball and seat increase by a factor of 3-4, which may lead to an increase in valve torque. However, the wear of the seat is found to be more significant than that of the ball. In addition, a comparison of the surfaces of the ball and seat before and after testing revealed that adhesive and abrasive wear are the major wear mechanisms. The results of this study may aid in the design of metal-seated ball valves from the tribological point of view.
Quantitative Evaluation of Tool Wear in Cold Stamping of Ultra-High-Strength Steel Sheets
Junho Bang,Minki Kim,Gihyun Bae,Junghan Song,Hong‑Gee Kim,이명규 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.2
The body of an automobile must be lightweight and crash-worthy. The use of advanced high-strength steel reduces the manufacturingcost for automobile body and improves energy absorption during an impact. However, increasing the strength ofthe steel sheet results in a variety of issues related to tool wear due to a higher forming pressure in the sheets than that in theconventional low-strength steel sheets. Therefore, systematic wear experimentation and evaluation procedure are required toquantify the extent of tool wear during the press forming process. This study aims to develop a methodology for quantifyingthe wear of a sheet metal forming tool using experimental databases. A progressive die set is designed to conduct the weartest systematically, saving both time and money. The testing machine is capable of testing four different types of punchessimultaneously under a variety of tooling and process parameters, such as different tool materials, punch shapes, and coatingconditions. The wear depth, roughness, and surface imaging of the tool are all used to establish quantitative evaluationmethods for tool wear in the sheet metal forming process. Consequently, we found that punches with small radius of curvaturewear rapidly, while tools and coatings with a high hardness have high resistance against wearing. Additionally, by referringto the measured wear database, it is confirmed that analyzing the reasonable tool wear characteristics is appropriate. Theproposed testing method can be used to obtain reliable results for quantitatively and qualitatively evaluating the wear lifetimeof various tool materials.
Characterization of Formed TRIP1180 Steel Sheet Surface After Stamping with PVD-Coated Tools
Junho Bang,Gihyun Bae,Minki Kim,Junghan Song,Myoung‑Gyu Lee,Hong‑Gee Kim 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.2
The wear tests are conducted on bending punches deposited with PVD CrN and AlTiCrN coatings using the newly proposedprogressive die. Then, the surface quality of the formed product is characterized through the surface roughness measurementafter forming of TRIP1180 steel sheets. The correlation between the tool wear, in terms of wear depth and roughness and theproduct surface roughness can be quantitatively analyzed. The results show that the roughness remains comparable to that ofthe as-received surface before failure occurs, which represents smooth product surface without severe scratches and defects. While micro scratches on the punch surface have no effect on the quality of the product surface, severe fretting wear on thepunch surface leads to a deterioration in the surface quality. Once initiated in the stamping process, the wear progressesexponentially within short time. The wear is also characterized as less than the coating thickness, but it results in completeremoval of the coating layer. The partially worn punch plows the product surface, causing surface scratches with grooves andridges, resulting in the roughness of 1.0 μm. In contrast, the surface with completely damaged coatings is extremely rough,with the roughness of 2.0 μm. This study presents the efficient method to evaluate the tool wear progression by indirectlymeasuring the product surface quality with reliably high precision.