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A Design Framework of FlexRay Network Parameter Optimization
Kwanghyun Jang,Inseok Park,Jaehyun Han,Myoungho Sunwoo,Eunjin Lee 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
In designing a FlexRay network, more than 70 configuration parameters are involved. Since these parameters are numerous and correlated to each other, FlexRay network design is complex and difficult work. Unfortunately, there are few systematic processes that help determining the FlexRay network parameters optimally. In this study, we propose a design framework that optimizes the FlexRay network parameters. We consider two main parameters that are highly relevant to the application algorithm: static (ST) slot length and communication cycle (CC) length. The design process is composed of two steps. In the first step, the ST slot length is optimized considering the frame packing algorithm. This frame packing algorithm binds network signals into ST frames in consideration of the periods and signal groups. In the second step, the CC length is optimized with regard to the worst case response times (WCRT) of ST and dynamic (DYN) frames. The WCRTs are analyzed based on the frame scheduling algorithm. The proposed design framework is applied in a case study.
Jo, Kwanghyun,Ahn, Sung Hwan,Chung, Kwangzoo,Cho, Sungkoo,Shin, Eunhyuk,Hong, Chae-Seon,Park, Seyjoon,Kim, Dae-Hyun,Lee, Boram,Lee, Woo-Jin,Seo, Se-Kwang,Jang, Jun-Young,Choi, Doo Ho,Lim, Do Hoon,Han, Korean Society of Medical Physics 2016 의학물리 Vol.27 No.4
We have treated various disease sites using wobbling and scanning proton therapy techniques since December 2015 at the Samsung Medical Center. In this study, we analyze the treatment time for each disease site in 65 wobbling and 50 scanning patient treatments. Treatment times are longest for liver and lung patients using the respiratory gating technique in the wobbling treatment and for cranio-spinal irradiation in pediatric patients with anesthesia in the scanning treatment. Moreover, we analyze the number of incidents causing treatment delays and the corresponding treatment delay time. The X-ray panel was the main reason for delays in the wobbling treatment; this decreased continually from January to June 2016, related closely to the proficiency of the human operators involved. The main reason for delays in the scanning treatment was interlocks during scanning pattern delivery; this was resolved by proton machine engineers. Through this work, we hope to provide other institutes with useful insight for initial operation of their proton therapy machines.
Dendrimer-Capped Gold Nanoparticles for Highly Reliable and Robust Surface Enhanced Raman Scattering
Kim, Kwanghyun,Lee, Jeongyeop,Jo, Gyeongcheon,Shin, Seungmin,Kim, Jin-Baek,Jang, Ji-Hyun American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.31
<P>Dendrimer-stabilized gold nanoparticles (Au-Den) were prepared by a facile solution based method for a highly reliable and robust surface enhanced Raman scattering (SERS) substrate. Au-Den was selectively attached on the surface of reduced graphene oxide (rGO) by noncovalent interactions between the Au capping dendrimer and the graphene surface. Au-Den/rGO exhibits the outstandingly stable and highly magnified Raman signal with an enhancement factor (EF) of 3.9 X 10(7) that enables detection of R6G dyes with concentration as low as 10 nM, retaining 95% of the Raman signal intensity after 1 year. The remarkable stability and enhancement originated not only from a simple combination of the electromagnetic and chemical mechanism of SERS but also from intensified packing density of stable Au Den on the graphene substrate due to the firm binding between the dendrimer capped metal nanoparticles and the graphene substrate. This method is not limited to the gold nanoparticles and G4 dendrimer used herein, but also can be applied to other dendrimers and metal nanoparticles, which makes the material platform suggested here superior to other SERS substrates.</P>
Kim, Kwanghyun,Kim, Ik-Hee,Yoon, Ki-Yong,Lee, Jeongyeop,Jang, Ji-Hyun The Royal Society of Chemistry 2015 Journal of materials chemistry. A, Materials for e Vol.3 No.15
<▼1><P>By simply pattering conductive FTO in a 3D-shape, we achieved 1.7 times greater photocurrent density in water splitting reactions.</P></▼1><▼2><P>Patterned FTO was fabricated <I>via</I> a facile method as an efficient current collector in a photoelectrochemical water splitting system. The photocurrent density of α-Fe2O3 on patterned FTO exhibited a 1.7 times increase relative to α-Fe2O3 on FTO due to the light scattering and rapid transfer of excited electrons.</P></▼2>
Three-dimensional solar steam generation device with additional non-photothermal evaporation
Kim, Kwanghyun,Yu, Sunyoung,Kang, Se-Young,Ryu, Seung-Tak,Jang, Ji-Hyun Elsevier Scientific Pub. Co 2019 Desalination Vol. No.
<P><B>Abstract</B></P> <P>The evaporation sites of a solar desalination device were expanded from conventional 2D to a new type of 3D by leaving the side area of the porous water transporter exposed to the air. The 3D solar desalination device permits not only photothermal distillation by the photoabsorbers at the top under sunlight illumination, but also additional non-photothermal evaporation on the side of the water transporter that works even at night by exploiting environmental heat. For the first time, we developed a unique configuration of water transport exposed to the environment with a great contribution to an active site increase and confirmed the significant impact of the active site increase on the solar desalination performance by systematic and strong pieces of evidence. Due to the effective utilization of enormous evaporation sites on the top and side surfaces in the 3D configuration, the device exhibited a significant steam generation rate of ~0.74 g/h under 1 sun illumination, which is ~1.5 times higher than the maximum value achieved with photothermal evaporation only. Our study suggests an innovative change which incorporates additional non-photothermal evaporation in the solar desalination device can be a straightforward and efficient way to address clean water deficiencies worldwide in the future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An innovative 3D solar desalination device with an exposed water transporter </LI> <LI> Both photothermal (top) and non-photothermal (side) evaporation occurred. </LI> <LI> Steam was generated steadily even at poor light conditions (cloudy or night time). </LI> <LI> A large steam generation rate (0.74 g/h) was obtained under 1 sun illumination. </LI> </UL> </P>
Kim, Kwanghyun,Thiyagarajan, Pradheep,Ahn, Hyo-Jin,Kim, Sun-I,Jang, Ji-Hyun The Royal Society of Chemistry 2013 Nanoscale Vol.5 No.14
<P>A gold nanoparticle-coated and surface-textured TiO2 inverse opal (Au/st-TIO) structure that provides a dramatic improvement of photoelectrochemical hydrogen generation has been fabricated by nano-patterning of TiO2 precursors on TiO2 inverse opal (TIO) and subsequent deposition of gold NPs. The surface-textured TiO2 inverse opal (st-TIO) maximizes the photon trapping effects triggered by the large dimensions of the structure while maintaining the adequate surface area achieved by the small dimensions of the structure. Au NPs are incorporated to further improve photoconversion efficiency in the visible region via surface plasmon resonance. st-TIO and Au/st-TIO exhibit a maximum photocurrent density of 0.58 mA cm(-2) and 0.8 mA cm(-2), which is 2.07 and 2.86 times higher than that of bare TIO, respectively, at an applied bias of +0.5 V versus an Ag/AgCl electrode under AM 1.5 G simulated sunlight illumination via a photocatalytic hydrogen generation reaction. The excellent performance of the surface plasmon-enhanced mesoporous st-TIO structure suggests that tailoring the nanostructure to proper dimensions, and thereby obtaining excellent light absorption, can maximize the efficiency of a variety of photoconversion devices.</P>
Kim, Kwanghyun,Yu, Sunyoung,Kim, Sung-Wook,Kim, Taegeon,Kim, Sang-Min,Kang, Se-Young,Han, Seung Min,Jang, Ji-Hyun The Royal Society of Chemistry 2017 Chemical communications Vol.53 No.58
<▼1><P>This is the first report on the fabrication of defect-free submicron structures with more than 100 μm thickness and an aspect ratio over 100.</P></▼1><▼2><P>This is the first report on the fabrication of defect-free submicron structures with more than 100 μm thickness and an aspect ratio over 100. Highly transparent poly(glycidyl methacrylate-<I>co</I>-acryloisobutyl POSS) (PGP) was synthesized <I>via</I> radical polymerization. The mechanical properties of the PGP submicron structure displayed a Young's modulus of 6.09 GPa and a hardness of 0.16 GPa, 4.2 and 8 times, respectively, than those of SU8 nanopatterns. These enhancements enable the utilization of ultrathick 2D-/3D-submicron structures as an ideal platform for microelectromechanical systems, big data storage systems, energy devices, <I>etc.</I></P></▼2>
Kim, Kwanghyun,Yu, Sunyoung,An, Cheolwon,Kim, Sung-Wook,Jang, Ji-Hyun American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.18
<P>Solar desalination via thermal evaporation of seawater is one of the most promising technologies for addressing the serious problem of global water scarcity because it does not require additional supporting energy other than infinite solar energy for generating clean water. However, low efficiency and a large amount of heat loss are considered critical limitations of solar desalination technology. The combination of mesoporous three-dimensional graphene networks (3DGNs) with a high solar absorption property and water-transporting wood pieces with a thermal insulation property has exhibited greatly enhanced solar-to-vapor conversion efficiency. 3DGN deposited on a wood piece provides an outstanding value of solar-to-vapor conversion efficiency, about 91.8%, under 1 sun illumination and excellent desalination efficiency of 5 orders salinity decrement. The mass-producible 3DGN enriched with many mesopores efficiently releases the vapors from an enormous area of the surface by heat localization on the top surface of the wood piece. Because the efficient solar desalination device made by 3DGN on the wood piece is highly scalable and inexpensive, it could serve as one of the main sources for the worldwide supply of purified water achieved via earth-abundant materials without an extra supporting energy source.</P> [FIG OMISSION]</BR>