https://scholar.korea.ac.kr/handle/2021.sw.korea/860 2026-04-05T15:56:35Z 2026-04-05T15:56:35Z Sharma, Krishna Prasad Shin, Miyeon Awasthi, Ganesh Prasad Gwak, Nayeong Kim, Sung Hoon Yu, Changho https://scholar.korea.ac.kr/handle/2021.sw.korea/270695 2025-05-28T09:01:40Z 2025-08-01T00:00:00Z

Title: Pani/MoS2 composite for an efficient catalyst for photocatalytic reduction and adsorption of chromium Cr (VI) Authors: Sharma, Krishna Prasad; Shin, Miyeon; Awasthi, Ganesh Prasad; Gwak, Nayeong; Kim, Sung Hoon; Yu, Changho Abstract: The development and use of a cost-effective, eco-friendly catalyst for the efficient removal of Cr (VI) from wastewater are critical. In response, we have created a Pani/MoS2 composite for adsorption, utilizing a binary organic–inorganic material produced through a combination of in-situ oxidative polymerization and hydrothermal reactions. This study highlights the significance of using a bifunctional organic–inorganic composite for Cr (VI) removal. The hydrothermally prepared Pani/MoS2 material serves as a bifunctional catalyst, facilitating both adsorption and photocatalytic reduction. Comprehensive characterization, photocatalysis, and adsorption analyses of the Pani/MoS2 composite provide valuable insights into its adsorption and reduction mechanisms. The results showed a reduction efficiency of 67.03% after 80 min and a removal efficiency of 73.60% at pH 3 after 24 h. Additionally, Pani/MoS2 exhibited an adsorption capacity of 29.44 mg/g after 24 h. The hybrid organic–inorganic composite contains multiple adsorption sites, resulting in enhanced adsorption capacity. The adsorption process involves a variety of reactions, including electrostatic interactions, complexation reactions, physical and chemical adsorption, reduction reactions, and photocatalytic reduction, which incorporates simultaneous oxidation and reduction through electron-hole pairs. A study on the stability and the effect of radical scavengers demonstrated the comparable stability of Pani/MoS2 and the role of radical interference during Cr (VI) adsorption. © 2025 Elsevier B.V.

2025-08-01T00:00:00Z Kim, Nayeon Jeong, Jiae Lee, Jae Woo Woo, Jiyong https://scholar.korea.ac.kr/handle/2021.sw.korea/270579 2025-05-28T09:00:50Z 2025-06-01T00:00:00Z

Title: Unraveling the role of post-annealing in IGZO transistor for memory applications Authors: Kim, Nayeon; Jeong, Jiae; Lee, Jae Woo; Woo, Jiyong Abstract: We demonstrate that post-annealing techniques are important for achieving the transfer characteristics of indium-gallium-zinc oxide (IGZO) transistors and identify that their role depends on the sputter-deposited IGZO film conditions. The as-fabricated transistor with a thin IGZO channel, HfO2 gate dielectric, and Mo gate electrode exhibits a constant drain current (IDS) over gate voltage (VGS). Although the oxygen (O2) plasma gas rate is adjusted from 0.2 to 1 sccm with an argon gas rate of 30 sccm during IGZO deposition, the IDS level was reduced by a factor of 104. Notably, VGS-controlled transfer behavior of the transistors only starts after post-annealing is performed at temperatures above 300 degrees C, regardless of which IGZO channel properties are used. More specifically, since oxygen vacancies (VOs) serve as carriers in the IGZO, annealing in different O2 gas or air environments to generate or reduce the number of VOs is found to be optimal for the VO-rich or VO-poor channels, respectively. In this study, we reveal that oxidation annealing appears to be a more effective way for achieving improved gate controllability (e.g., subthreshold swing). Accordingly, we further analyze how the VOs in the IGZO are involved in switching by examining the effect of annealing temperature and gate dielectric materials on the transfer curve. These results indicate that VOs in the bulk need to be annihilated to lower the off-state IDS, while a sufficient number of VOs near the channel and gate dielectric interface should be ensured to responded by VGS for rapid switching.

2025-06-01T00:00:00Z Park, Junkyeong Yang, Younghwan Park, Yujin Kang, Hyunjung Shin, Jehyeon Keawmuang, Harit Kim, Won-Sik Badloe, Trevon Kim, Young-Ki Rho, Junsuk https://scholar.korea.ac.kr/handle/2021.sw.korea/270737 2025-06-10T01:17:38Z 2025-05-14T00:00:00Z

Title: Electrically Tunable Metasurfaces for Broadband Beam Splitting Across the Visible Spectrum Authors: Park, Junkyeong; Yang, Younghwan; Park, Yujin; Kang, Hyunjung; Shin, Jehyeon; Keawmuang, Harit; Kim, Won-Sik; Badloe, Trevon; Kim, Young-Ki; Rho, Junsuk Abstract: Tunable metasurfaces for beam-splitting hold potential applications in optical computing, communication, and sensing. However, existing approaches have been demonstrated mostly in gigahertz (GHz) and terahertz (THz) frequency ranges due to the limited scalability of current nanofabrication techniques and the scarcity of suitable materials for efficient metasurfaces in the visible spectrum. In this work, an electrically tunable metasurface for beam-splitting is introduced by combining liquid crystal (LC) cells with a titanium dioxide particle-embedded resin (TiO2-PER), a scalable, high-refractive-index, low-loss material designed for mass production. By integrating LC cells with a broadband gradient metasurface, dynamic beam splitting is achieved through real-time polarization switching within the LC cells under applied electric fields. Nanoimprint lithography (NIL) with TiO2-PER, supported by established liquid crystal display (LCD) industry technologies, enables scalable and cost-effective manufacturing, providing a practical solution for next-generation optical devices that integrate electronic and photonic signals.

2025-05-14T00:00:00Z Han, Chang-Hee Kim, Seong-Uk Lim, Kyung-Soo Jung, Young-Jin Lee, Sangho Kim, Sung Hoon Hwang, Han-Jeong https://scholar.korea.ac.kr/handle/2021.sw.korea/269338 2025-05-13T03:00:21Z 2025-05-01T00:00:00Z

Title: Evaluation of a silicone-based flexible dry electrode for measuring human bioelectrical signals Authors: Han, Chang-Hee; Kim, Seong-Uk; Lim, Kyung-Soo; Jung, Young-Jin; Lee, Sangho; Kim, Sung Hoon; Hwang, Han-Jeong Abstract: The development of conductive polymer-based dry electrodes with high conductivity is promising for practical applications in daily life due to their biocompatibility, flexibility, lightweight, and comfort. The objective of this study is to demonstrate the feasibility of using a novel silicone-based dry electrode for measuring various bioelectrical signals.The silicone-based electrode, manufactured using an optimized polymer matrix, combines high conductivity with flexibility, ensuring superior wearability and reliable bioelectrical signal monitoring. To evaluate its performance, we compared its impedance and flexibility with those of a commercial electrode. Additionally, its compatibility for measuring biological signals was assessed through performance comparisons across various bioelectrical signals. Fourteen healthy participants performed three experimental paradigms: (1) eyes closed and open to measure alpha electroencephalography (EEG) as well as resting-state electrocardiography (ECG), (2) eye blinking to measure electrooculography (EOG), and (3) wrist movement to measure electromyography (EMG). All bioelectrical signals were measured simultaneously using both the silicone-based dry electrode and a commercial dry electrode. The performance of the silicone-based dry electrode was evaluated by comparing the signal quality of both electrodes. The silicone-based dry electrode exhibited lower electrical impedance (39.43 k Omega on average, p = 0.0058) and greater flexibility (Young's modulus: silicone 1.51 +/- 0.10 MPa vs. commercial 2.46 +/- 0.38 MPa) compared to the commercial dry electrode. Overall, there were minimal differences in signal quality between the two electrodes: i) EEG (alpha power SNR: silicone 1.39 +/- 0.34 vs. commercial 1.36 +/- 0.29), ii) ECG (R-peak recall: 99.20 +/- 2.50%, correlation coefficient: 0.96 +/- 0.08), iii) EOG (eye blink recall: 100.00%, correlation coefficient: 0.98 +/- 0.03), and iv) EMG (no significant difference in SNR values). These findings indicate that the developed electrode not only ensures superior flexibility but also maintains compatible electrical properties for measuring various bioelectrical signals.

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