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Korea Pathfinder Lunar Orbiter (KPLO) Operation: From Design to Initial Results
Moon-Jin Jeon,Young-Ho Cho,김은혁,Dong-Gyu Kim,Young-Joo Song,홍승범,Jonghee Bae,Jun Bang,Jo Ryeong Yim,Dae-Kwan Kim 한국우주과학회 2024 Journal of Astronomy and Space Sciences Vol.41 No.1
Korea Pathfinder Lunar Orbiter (KPLO) is South Korea’s first space exploration mission, developed by the Korea Aerospace Research Institute. It aims to develop technologies for lunar exploration, explore lunar science, and test new technologies. KPLO was launched on August 5, 2022, by a Falcon-9 launch vehicle from cape canaveral space force station (CCSFS) in the United States and placed on a ballistic lunar transfer (BLT) trajectory. A total of four trajectory correction maneuvers were performed during the approximately 4.5-month trans-lunar cruise phase to reach the Moon. Starting with the first lunar orbit insertion (LOI) maneuver on December 16, the spacecraft performed a total of three maneuvers before arriving at the lunar mission orbit, at an altitude of 100 kilometers, on December 27, 2022. After entering lunar orbit, the commissioning phase validated the operation of the mission mode, in which the payload is oriented toward the center of the Moon. After completing about one month of commissioning, normal mission operations began, and each payload successfully performed its planned mission. All of the spacecraft operations that KPLO performs from launch to normal operations were designed through the system operations design process. This includes operations that are automatically initiated post-separation from the launch vehicle, as well as those in lunar transfer orbit and lunar mission orbit. Key operational procedures such as the spacecraft’s initial checkout, trajectory correction maneuvers, LOI, and commissioning were developed during the early operation preparation phase. These procedures were executed effectively during both the early and normal operation phases. The successful execution of these operations confirms the robust verification of the system operation.
대형보 실험을 통한 TBM 터널 세그먼트용 강섬유보강콘크리트 성능평가
문도영,노화성,장수호,이규필,배규진,Moon, Do-Young,Roh, Hwasung,Chang, Soo-Ho,Lee, Gyu-Phil,Bae, Gyu-Jin 한국터널지하공간학회 2014 한국터널지하공간학회논문집 Vol.16 No.3
본 연구에서는 TBM 터널 SFRC 세그먼트 개발을 위하여 이형철근이 보강되지 않은 SFRC 보의 휨파괴 실험을 통하여 SFRC 배합의 평가를 수행하였다. 압축강도, 강섬유의 형상비와 강섬유 혼입률을 변수로 하여 총 16개의 SFRC 보를 제작하고 휨에 의하여 파괴시까지 실험하였다. 하중-수직변위 분석결과, 큰 형상비의 강섬유를 사용하여도 소형보의 실험(Moon et al, 2013)과 달리 보의 인성거동을 증진시키는 효과는 거의 없는 것으로 나타났다. 극한상태에서 강섬유는 균열폭 7 mm까지 하중을 저항하는 것으로 확인되었다. 또한, 기존의 SFRC 보의 휨강도예측모델과 실험결과를 비교한 결과, SFRC 보의 휨강도를 최대 20배까지 과소평가하고 있는 것으로 나타났다. 그러나, TR No. 63 모델(Concrete Society, 2011)은 다른 모델에 비하여 근사하게 휨강도를 예측하는 것으로 확인되었다. 강섬유의 분포에 대한 분석결과, 소형보에서 보다 실제 규모의 보에서 강섬유의 분산도가 훨씬 개선되는 것을 확인하였다. In order to develop SFRC TBM tunnel segment, evaluating the SFRC mixture was conducted through flexural tests of SFRC beams without ordinary steel reinforcement in this study. Considered variables were compressive strengths of SFRC, aspect and mix ratio of steel fibers and total 16 specimens were fabricated and tested until failure. The load-vertical displacement results demonstrates that the effect of aspect ratio is minor when compared to results form small beam test(Moon et al, 2013). A SFRC beam resists the vertical load until the width of crack reaches to 7 mm due to steel fibers across cracked surfaces. Moreover, it is found that flexural moment estimated by equation of TR No. 63(Concrete Society, 2011) is useful for prediction of nominal strength for SFRC structure. From the investigation of fiber distribution in cracked section, it is found that dispersion improved in actual size beam compared to in standard small beam for evaluation of flexural strength.
Fabrication and analysis of enforced dry adhesives with core–shell micropillars
Bae, Won-Gyu,Kwak, Moon Kyu,Jeong, Hoon Eui,Pang, Changhyun,Jeong, Hakgeun,Suh, Kahp-Yang The Royal Society of Chemistry 2013 Soft matter Vol.9 No.5
<P>We present a simple method for fabricating robust dry adhesives by coating a soft polydimethyl siloxane (PDMS) thin layer on rigid backbone micropillars of polyurethane acrylate (PUA). These core–shell type micropillars demonstrated enhanced durability both in normal and shear adhesion over more than 100 cycles of attachment and detachment. Relatively strong normal (∼11.4 N cm<SUP>−2</SUP>) and shear (∼15.3 N cm<SUP>−2</SUP>) adhesion forces were observed, which were similar to or even larger than those of homogeneous PDMS micropillars. A simple theoretical model based on beam deflection theory was used to explain the experimental results.</P> <P>Graphic Abstract</P><P>Robust dry adhesives with core–shell micropillars are described by combining replica molding and thin film coating. The core–shell micropillars allow for a relatively high adhesion force (∼15.3 N cm<SUP>−2</SUP>) similar to homogeneous PDMS micropillars and enhanced durability over 100 cycles of attachment and detachment. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2sm27323c'> </P>
Stress-relieved Si anode on a porous Cu current collector for high-performance lithium-ion batteries
Moon, Sang-Hyun,Kim, Si-Jin,Kim, Min-Cheol,So, Jin-Young,Lee, Ji-Eun,Shin, Yeon-Kyung,Bae, Won-Gyu,Park, Kyung-Won Elsevier 2019 Materials chemistry and physics Vol.223 No.-
<P><B>Abstract</B></P> <P>To overcome the mechanical stress generated during the cycling process in lithium-ion batteries, Si anode is fabricated on a porous Cu current collector with holes using sputtering deposition method. The porous Cu/Si shows superior high-rate and cycling performance in lithium-ion batteries compared to the Si anode on the flat Cu. The excellent high-rate performance and stable cyclability of the porous Cu/Si can be predominantly attributed to the efficient relief of the stress generated by the volumetric expansion of the Si anode on the porous Cu current collector.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Si anode for LIBs was fabricated on a porous Cu current collector having holes. </LI> <LI> The porous Cu/Si showed the superior high-rate and cycling performance. </LI> <LI> The excellent performance of the porous Cu/Si can be due to the relief of the stress. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Optimized low-temperature fabrication of WO<sub>3</sub> films for electrochromic devices
Bae, Jaehyun,Seo, Dong Gyu,Park, Su Mi,Park, Kyu Tae,Kim, Haekyoung,Moon, Hong Chul,Kim, Se Hyun Institute of Physics Publishing Ltd. 2017 Journal of Physics. D, Applied Physics Vol.50 No.46
<P>We investigated the effect of process conditions on the electrochromic (EC) properties of tungsten trioxide (WO<SUB>3</SUB>) films. When WO<SUB>3</SUB> films deposited using a sol-gel method were thermally treated in air at 150 °C, the majority of tungsten species in the films became W<SUP>6+</SUP>, which is important for the realization of an optically transparent bleached state. On the other hand, annealing in a vacuum required only 60 °C to induce a similar level of W<SUP>6+</SUP> in the WO<SUB>3</SUB> films. However, a cracked film morphology was observed at higher temperatures, regardless of whether the films were annealed in air or vacuum. Using the WO<SUB>3</SUB> films prepared under various conditions, EC devices (ECDs) were fabricated to evaluate EC properties. We concluded that the optimal annealing conditions for WO<SUB>3</SUB> films for ECDs are 60 °C in vacuum, at which the highest coloration efficiency, largest transmittance difference, and fastest bleaching/coloration dynamics were obtained. These mild fabrication conditions at a low temperature (60 °C) provide the opportunity to utilize flexible electrodes on plastic. Therefore, we successfully demonstrated a flexible WO<SUB>3</SUB>-based ECD.</P>
Bae, Chun-Sik,Oh, Dong-Min,Bae, Jin-Gyu,Kim, Jong-Choon,Kim, Sung-Ho,Kim, Su-Gwan,Jeong, Moon-Jin,Kim, Youn-Shin,Lim, Sung-Chul Blackwell Science, Ltd 2006 Basic & clinical pharmacology & toxicology Vol.98 No.4
<P>Abstract: </P><P>Gemifloxacin is a synthetic fluoroquinolone antimicrobial agent that exhibits potent activity against most Gram-negative and Gram-positive organisms, and has a comparatively low chondrotoxic potential in immature animals. This study examined the effects of gemifloxacin on the Achilles tendons in immature Sprague-Dawley rats treated by oral intubation once daily for 5 consecutive days from postnatal week 4 onward at doses of 0 (vehicle), and 600 mg/kg body weight. Ofloxacin or ciprofloxacin were used for comparison. The Achilles tendon specimens were examined by electron microscopy. In comparison with the vehicle-treated controls, there were ultrastructural changes in all samples from the gemifloxacin-, ofloxacin-, and ciprofloxacin-treated rats. Degenerative changes were observed in the tenocytes, and the cells that detached from the extracellular matrix were recognizable. The degree of degenerative changes and the number of degenerated cells in the Achilles tendon were significantly higher in the treated group than in the control group. Moreover, among the quinolone-treated groups, these findings were most significant in the ofloxacin-treated group, and least significant in the gemifloxacin-treated group. It is unclear what these findings mean with respect to the possible risk in juvenile patients treated with gemifloxacin or other quinolones. However, these results show that gemifloxacin causes less changes in the connective tissue structures.</P>
Enhanced Skin Adhesive Patch with Modulus-Tunable Composite Micropillars
Bae, Won Gyu,Kim, Doogon,Kwak, Moon Kyu,Ha, Laura,Kang, Seong Min,Suh, Kahp Y. Wiley (John WileySons) 2013 Advanced healthcare materials Vol.2 No.1
<P>Modulus-tunable composite micropillars are presented by combining replica molding and selective inking for skin adhesive patch in 'ubiquitous'-health diagnostic devices. Inspired from hierarchical hairs in the gecko's toe pad, a simple method is presented to form composite polydimethylsiloxane (PDMS) micropillars that are highly adhesive (1.8 N cm(-2) ) and mechanically robust (30 cycles).</P>
Moon, Jeong-Chan,Hah, Young-Sool,Kim, Woe-Yeon,Jung, Bae-Gyo,Jang, Ho-Hee,Lee, Jung-Ro,Kim, Sun-Young,Lee, Young-Mee,Jeon, Min-Gyu,Kim, Choong-Won,Cho, Moo-Je;,Lee, Sang-Yeol Plant molecular biology and biotechnology research 2005 Plant molecular biology and biotechnology research Vol.2005 No.
Although biochemical properties of 2-Cys peroxiredoxins (Prxs) have been extensively studied, their real physiological functions in higher eukaryotic cells remain obscure and certainly warrant further study. Here we demonstrated that human (h) PrxⅡ, a cytosolic isotype of human 2-Cys Prx, has dual functions as a peroxidase and a molecular chaperone, and that these different functions are closely associated with its adoption of distinct protein structures. Upon exposure to oxidative stress, hPrxⅡ assumes a high molecular weight complex structure that has a highly efficient chaperone function. However, the subsequent removal of stressors induces the dissociation of this protein structure into low molecular weight proteins and triggers a chaperone-to-peroxidase functional switch. The formation of a high molecular weight hPrxⅡ complex depends on the hyperoxidation of its N-terminal peroxidatic Cys residue as well as on its C-terminal domain, which contains a "YF motif" that is exclusively found in eukaryotic 2-Cys Prxs. A C-terminally truncated hPrxⅡ exists as low and oligomeric protein species and does not respond to oxidative stress. Moreover, this C-terminal deletion of hPrxⅡ converted it from an oxidation-sensitive to a hyperoxidation-resistant form of peroxidase. When functioning as a chaperone, hPrxⅡ protects HeLa cells from H_(2)O_(2)-induced cell death, as measured by a terminal deoxynucleotidyltransferase-mediated dUTP nickend labeling assay and fluorescence-activated cell sorting analysis.