Search

Your search keyword '"Park, Sang Hyeok"' showing total 48 results
Start Over Author "Park, Sang Hyeok"
48 results on '"Park, Sang Hyeok"'

15. Prophylactic efficacy of Lactobacillus curvatus B67-derived postbiotic and quercetin, separately and combined, against Listeria monocytogenes and Salmonella enterica ser. Typhimurium on processed meat sausage

Author

Toushik, Sazzad Hossen, primary, Kim, Kyeongjun, additional, Park, Sang-Hyeok, additional, Park, Jun-Ha, additional, Ashrafudoulla, Md., additional, Ulrich, Mevo Senakpon Isaie, additional, Mizan, Md. Furkanur Rahman, additional, Hossain, Md. Iqbal, additional, Shim, Won-Bo, additional, Kang, Iksoon, additional, and Ha, Sang-Do, additional

Published
2023
Full Text
View/download PDF

19. Laminating Structure for Interlayer Corona Discharge Treatment Toward Ion‐Based Nanogenerators.

Author

Park, Sang Hyeok, Lee, Jeongwan, Kong, Dae Sol, Choi, Jinhyeok, Jung, Hyeongjun, Park, Yong Jun, Park, Hyeong Min, Jung, Jong Hoon, and Lee, Minbaek

Subjects
*CORONA discharge, *LAMINATED materials, *CHARGE injection, *TRIBOELECTRICITY, *ANIONS, *NANOWIRES, *ELECTRONS
Abstract

A corona discharge treatment (CDT) is utilized to maximize the performance of triboelectric nanogenerators (TENGs) by injecting extra electrons into the negative tribomaterials. Increased performance of CDT TENGs, however, exhibits rapid degradation due to the electron dissipation by air moisture or thermal emission. To overcome such drawbacks and circumvent such dissipation, the source of charges should be replaced with ionic charges. This study reports a Ag nanowires (NWs)‐embedded laminating structure (AeLS) with a unique fabrication procedure for ionic charge injection by CDT. The injection of ions is achieved by interlayer‐CDT (i‐CDT), in which positive charges are dissipated by Ag NWs, and the opposite negative ions can remain on the outmost surface. The AeLS TENGs with i‐CDT exhibit high performance, long‐term stability, and durability. It shows voltage, current, and maximum power outputs of 380 V, 15 µA, and 827 mW m−2, respectively. As a practical demonstration, rotational TENG integrated with a direct discharge system is realized, and its current and voltage reach 7.4 mA and 7800 V, respectively. This work can pave the way for the design of ion‐based TENGs with high performance and long‐lasting retention of triboelectric charges. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

26. Simultaneous effect of cathode potentials and magnetite concentrations on methanogenesis of acetic acid under different ammonia conditions.

Author

Yulisa, Arma, Lee, Joonyeob, Park, Sang Hyeok, and Hwang, Seokhwan

Subjects
AMMONIA, ANAEROBIC digestion, CATHODES, MAGNETITE, CHARGE exchange, POWER resources, ACETIC acid
Abstract

Electromethanogenesis (EM) is a system that facilitates direct interspecies electron transfer (DIET) in anaerobic digestion (AD) by providing an external power supply to favor desired reactions. Substrates of AD commonly contain ammonia (NH3) as biodegradation product of nitrogen-rich compounds that can deteriorate the stability of AD process. Optimized cathode potential (VCAT) and magnetite (Mag) concentration ([Mag]) are expected to improve AD efficiency in the presence of NH3. Response surface analysis with central composite face-centered design was used in this study to investigate the effect of VCAT and [Mag] under different total ammonia nitrogen concentration ([TAN]). Highest cumulative methane production was achieved at VCAT = -737.4 mV, [Mag] = 18.2 mM, and [TAN] = 1.5 g/L; highest acetate degradation rate was achieved at VCAT = 757.6 mV, [Mag] = 21.4 mM, and [TAN] = 1.5 g/L. The study demonstrated that VCAT promotes either microbial growth or electrochemical NH3 removal. A Shift from acetoclastic to hydrogenotrophic pathway was also observed by the increase of hydrogenotrophic methanogen populations at the end of experiment. This study is beneficial for process control of AD under different NH3 conditions. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

28. Bi-exponential decay model of electron in Al2O3/Au NCs/Al2O3 structure.

Author

Choi, Jinhyeok, Park, Jinhong, Park, Sang Hyeok, Park, Yong Jun, Lee, Jeongwan, Murillo, Gonzalo, Kim, Misuk, Lee, Kyu-Tae, and Lee, Minbaek

Subjects
ATOMIC force microscopy, ELECTRONS
Abstract

As state-of-the-art electronic chips were miniaturized to its limit, many small dimension issues, such as crosstalk noise, parasite capacitance, and tunneling of charges, emerged. Studying such issues shall be of interest to the research and industry field. Here, we studied the electrical behavior of electrons injected in an array of nanostructures embedded on Al2O3 dielectrics. Our multi-stack device comprised Au nanoclusters, tunneling and blocking Al2O3 oxide layers, and a Si substrate. The electrons were injected by applying a bias at the top of the atomic force microscopy tip in contact while grounding the Si substrate. Its retention and diffusion behaviors were observed by measuring the contact potential difference (CPD). The measured CPD data with time were well fitted to the bi-exponential function, which had two time constants τ1 and τ2. It indicated that at least two dominant tunneling mechanisms existed, so it was confirmed with I–V measurement using a simple tunneling device (Pt/Al2O3/Si structure). This work may provide a tool for analysis of charge transportation in a miniaturized nanostructure. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

47. Correlation between frictional heat and triboelectric charge: In operandotemperature measurement during metal-polymer physical contact

Author

Lee, Dong Woo, Kong, Dae Sol, Kim, Jong Hun, Park, Sang Hyeok, Hu, Ying Chieh, Ko, Young Joon, Jeong, Chan Bae, Lee, Seoku, Il Jake Choi, Joong, Lee, Gwan-Hyoung, Lee, Minbaek, Wie, Jeong Jae, Chang, Ki Soo, Park, Jeong Young, and Jung, Jong Hoon

Abstract

In operandotechniques have emerged to elucidate the fundamental mechanism of triboelectrification via relevant physical quantity measurement during the physical contact of two materials. Here, a correlation between frictional heat and triboelectric charge is reported in a metal-polymer triboelectric nanogenerator through the in operandotemperature measurement. Fluorine-doped tin oxide (FTO) metal is slid back-and-forth under different contact pressures across polydimethylsiloxane (PDMS) polymers having different degrees of crosslinking, i.e., mixing ratio. Both the triboelectric charge and temperature variation increase and become saturated with different time-constants. Notably, the saturated triboelectric charge increases, while the saturated temperature decreases, with increasing mixing ratio. In contrast, both saturated triboelectric charge and temperature increase with increasing contact pressure. X-ray photoemission spectroscopy reveals that chemical bonds are modified inhomogeneously at the surface, and that charged materials are transferred from PDMS to FTO in accordance with the mixing ratio- and sliding time-dependent triboelectric charges. Frictional heat plays a distributive role in bond rupture and temperature variation, depending on the activation energy and frictional coefficient of PDMS. In operandotemperature variation measurement provides important information on the specific bonds for triboelectrification and detailed charge-transfer process during physical contact.

Published
2022
Full Text
View/download PDF

48. Toxic Gas-Free Synthesis of Extremely Negative Triboelectric Sulfur Copolymer Blends Via Phase Separation of Fluorine-Rich Polymers

Author

Choi, Jinhyeok, Won, Sukyoung, Yoon, Hyeok Jun, Lee, Jong Hyeok, Jang, Hye Woon, Jeon, Jisoo, Kim, A Young, Park, Sang Hyeok, Youk, Ji Ho, Lee, Minbaek, and Wie, Jeong Jae

Abstract

Recently, we reported surface fluorination of sulfur-based polymers to introduce a new class of extremely negative triboelectric material. However, the direct surface fluorination requires the use of toxic fluorine gas. In this study, we report the toxic gas-free synthesis of extremely negative triboelectric sulfur-rich polymers via the phase separation of a fluorine-rich polymer, poly(2,3,4,5,6-pentafluorostyrene) (PPFS), from sulfur copolymers. PPFS was physically mixed in situ during the inverse vulcanization of elemental sulfur, a by-product of petroleum refining to prepare the polymer blends. Hot pressing of the blends into films induced the phase separation of the hydrophobic PPFS; subsequently, PPFS migrates to the hydrophobic air interface to minimize the interfacial energy. A triboelectric nanogenerator (TENG) based on the phase separated blend films presented long-term stable voltage and current outputs that are 8-fold and 9-fold higher, respectively, than those of a TENG based on polytetrafluoroethylene (PTFE), a well-known extremely negative triboelectric polymer. We also demonstrate the ability of a TENG based on a 81.1 cm2-sized blend film to power 400 series-connected blue LEDs of 3.3V; a triboelectric open-circuit voltage output of 1362.4V is obtained under a minimal force of 30N. The demonstrated phase-separation strategy for fluorine-rich polymers will thus provide insights for achieving low-cost, environment-friendly, and high-performance triboelectric energy harvesting.

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results