Zero Fire Battery Concept for ESS: Water-in-Battery

Junho Bae,Jaebeom Jung,Yunseok Choi,Youngsik Kim,Hyuntae Bae,Jihun Cho 한국신재생에너지학회 2022 AFORE Vol.2022 No.9

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>

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.

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.

Degradation Progression of Polyurethane Hydraulic Reciprocating Seal

배준호(Junho Bae),정구현(Koo-Hyun Chung) Korean Society for Precision Engineering 2018 한국정밀공학회지 Vol.35 No.7

In this work, the degradation progression of a polyurethane (PU) hydraulic reciprocating seal with respect to the sliding distance were investigated using a pin-on-reciprocating tribo-tester. Also, the acceleration effect of alumina particles added in lubricant on degradation of PU seal were assessed, with an aim to contribute to the development of accelerated wear testing methods. As a result, It was shown that the height of PU specimens decreased drastically at the initial stage of sliding. Then, the height decrease was found to become gradual as sliding distance further increased. The result also shows that the height decrease of the PU specimen was mainly due to the effect of the compression set and wear. In addition, the noted abrasive wear of the PU specimens was found to be significantly accelerated due to the alumina particles in lubricant, which determined a further result in 50 % faster height decrease with increasing sliding distance, as compared to the normal lubricant. The outcome of this work may provide significant and useful information for the prediction of the lifetime of a hydraulic reciprocating seal, and for the continued development of accelerated wear testing of the hydraulic reciprocating seal.

멀티피직스 기반 리튬 이온 배터리 온도 조절용 PCB 발열 회로 해석 시뮬레이터 개발

배준호(Junho Bae),곽창섭(Chang-Seob Kwak) 대한전기학회 2023 대한전기학회 학술대회 논문집 Vol.2023 No.10

AKR2A-mediated import of chloroplast outer membrane proteins is essential for chloroplast biogenesis

Bae, Wonsil,Lee, Yong Jik,Kim, Dae Heon,Lee, Junho,Kim, Soojin,Sohn, Eun Ju,Hwang, Inhwan Nature Publishing Group 2008 Nature cell biology Vol.10 No.2

In plant cells, chloroplasts have essential roles in many biochemical reactions and physiological responses. Chloroplasts require numerous protein components, but only a fraction of these proteins are encoded by the chloroplast genome. Instead, most are encoded by the nuclear genome and imported into chloroplasts from the cytoplasm post-translationally. Membrane proteins located in the chloroplast outer envelope membrane (OEM) have a critical function in the import of proteins into the chloroplast. However, the biogenesis of chloroplast OEM proteins remains poorly understood. Here, we report that an Arabidopsis ankyrin repeat protein, AKR2A, plays an essential role in the biogenesis of the chloroplast OEM proteins. AKR2A binds to chloroplast OEM protein targeting signals, as well as to chloroplasts. It also displays chaperone activity towards chloroplast OEM proteins, and facilitates the targeting of OEP7 to chloroplasts in vitro. AKR2A RNAi in plants with an akr2b knockout background showed greatly reduced levels of chloroplast proteins, including OEM proteins, and chloroplast biogenesis was also defective. Thus, AKR2A functions as a cytosolic mediator for sorting and targeting of nascent chloroplast OEM proteins to the chloroplast.

공무원연금의 소득이전효과 분석

배준호 한국사회보장학회 2001 社會 保障 硏究 Vol.17 No.1

본 고에서는 공무원 퇴직자에 대한 연금을 통한 소득이전규모를 제시하고 있다. 공무원연금법은 2000년말에 큰 폭의 개정이 이루어졌는데 여기선 개정법의 영향을 받지 않는 2000년 수급자를 예로 들어 소득이전규모와 수익비, 내부수익율을 계산하여 제시하고 있다. 30년 근속자는 소득이전 규모가 2억6천만원(9급 임용)에서 3억8천만원(5급 임용) 정도로 나타나고 수익비(퇴직연금 현가/갹출금 현가)는 3.8~3.9배로 직급별로 차이가 거의 없다. 내부수익률도 17.5~17.7%로 직급에 관계없이 아주 높다. 두드러진 점은 근속연수가 비교적 짧은 20년 근속자의 수익비가 4.6~4.9배로 30년 이상 근속자의 그것보다 더 높다는 것인데 이는 연금수령기간이 길기 때문일 것이다. 이상의 값은 할인율로 회사채수익률을 사용하여 얻은 것인데 낮은 할인율인 공무원연금기금의 유가증권운용수익률을 사용하면 소득이전규모는 2억7천만원에서 4억원으로 수익비는 4.5~4.7배로 늘어난다. This paper calculate the income transferred to the civil servant retiree who have worked 20 years more through Korean civil servant retirement pension. The law of Korean civil servant pension was amended in the various aspect at December 2000. We are focusing the retirees in 2000 to whom applied the law before amendment and calculate the present value of income transferred, benefits/contributions ratio, internal rate of return. The result shows that income transferred amount to 260 million won(servant start on 9th grade), 380 million won(servant start on 5th grade). And B/C ratio shows 3.8-3.9 not different from starting grade. Also internal rate of return is 17.5-17.7% very high irrelevant of starting grade. Particularly B/C ratio for the retiree having 20 years work period shows 4.6-4.9, above that for the 30 years and over. That is why the former have longer benefits period than the latter. Above figures are derived using discount rate of debenture interest rate, but if using other rate such as securities' earnings rate resulting from Korean civil servant pension fund's fund management, the income transferrd increase to 270-400 million won, B/C ratio to 4.54.7.

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.