https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/185 Sat, 04 Jul 2026 05:58:45 GMT 2026-07-04T05:58:45Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213325 Title: A two-phase topology optimization method for manufacturable functionally-graded lattice structures with casting process Authors: Yi, Bing; Liu, Long; Wang, Tianci; Peng, Xiang; Yoon, Gil-Ho Abstract: Topology optimization often yields intricate truss-like structures that are challenging to fabricate using conventional manufacturing methods. To deal with this issue, this paper proposes a two-phase topology optimization method to enhance the manufacturability of functionally-graded lattice structures with the casting process. Specifically, the minimal length scales of two phases, including void and solid phases are proposed to exactly align with the manufacturing constraints of the final product and its mold. Additionally, a penalty function is employed to eliminate grey elements, ensuring a clear, easily manufacturable solution for both the cast product and its mold. Finally, the two-phase-based topology optimization of both conventional continuous structures and functionally-graded lattice structures is formulated, and the product and its mold are optimized simultaneously via the Method of Moving Asymptotes (MMA). Numerical examples of both the conventional SIMP method and the integration of functionally-graded lattice structures are used to demonstrate the effectiveness of the proposed method in simultaneously optimizing both the product and casting. To validate the approach, a functionally-graded lattice structure was successfully cast using aluminum alloy, confirming the practical applicability of the method. Tue, 01 Dec 2026 00:00:00 GMT https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213325 2026-12-01T00:00:00Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213315 Title: Improvement of natural convection heat dissipation of a conventional pin-fin heat sink by applying a helical wire spring Authors: Kang, Hyeon-Min; Ko, Jae-Yong; Zulkifli, Noraina Zulaikha Awang; Yusof, Nur Ain Syafiqah; Yook, Se-Jin Abstract: Effective heat dissipation of electronic devices including high-power light-emitting diodes (LEDs) is essential in applications requiring both compact size and high performance. In such environments, passive cooling technologies providing high heat dissipation with simple structures are particularly desirable. This study proposes a new method to enhance the cooling performance of conventional pin-fin heat sinks by applying a spring-shaped wire structure around the outer surfaces of the fins. Aluminum 6061 or SAC305 wire was formed into a helical spring and wrapped around the fins without altering the original heat sink geometry, enabling attachment to existing products. The spring structure increases the effective surface area and guides airflow between fins, thereby enhancing free convection heat transfer. Experiments and numerical simulations were conducted to evaluate the thermal performance of the proposed design. For the reference heat sink without springs, a simple rising buoyant flow developed between the fins. In contrast, the spring-equipped heat sink induced more complex flow paths along the spring geometry, promoting enhanced air circulation. This resulted in more uniform heat distribution and a reduction in overall thermal resistance. Comparative analysis under different installation angles showed that the aluminum-spring-applied heat sink achieved a maximum thermal-resistance reduction of 11.72% relative to the reference model, demonstrating consistent performance improvement under various orientations. These results show that the simple addition of a spring structure can significantly improve the natural-convection cooling performance of conventional heat sinks, indicating its potential as a scalable and feasible thermal management solution for high-power electronic devices and LED lighting systems. Sun, 01 Nov 2026 00:00:00 GMT https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213315 2026-11-01T00:00:00Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213326 Title: Cellulose-based conductive cotton textiles for wearable healthcare sensing: From materials to fabrication Authors: Woo, Jeongwoo; Park, Siwon; Kim, Sangjun; Kim, Dongyeong; Chang, Taehoo; Kim, Min Ku Abstract: As wearable technologies become increasingly integrated into daily life, the need for functional and human-friendly materials has grown. Cellulose-based natural textiles, especially cotton, meet this demand through intrinsic comfort, breathability, sustainability, and compatibility with the human body. This review focuses on recent advances in converting cotton into conductive textile sensing platforms for wearable healthcare. Major conductive material classes are covered, including carbon materials, metals, conductive polymers, and MXenes, together with practical fabrication methods such as coating, printing, deposition, and carbonization. Particular attention is given to how the structure and surface chemistry of cotton influence material integration, conductivity, mechanical robustness, breathability, and sensing reliability across representative textile sensors. Representative textile sensors for mechanical, electrophysiological, and chemical signals are summarized, along with integration strategies for stable skin contact and reliable signal readout. Integrated sensor systems for continuous health monitoring are also introduced to link textile sensors with practical wearable operation. Finally, added functionalities for real-world operation are considered, including self-powered sensing, superhydrophobicity, antimicrobial activity, and EMI shielding. By connecting materials, fabrication, sensing performance, and practical operation, this review outlines directions for sustainable and multifunctional textile health-monitoring systems for personalized medicine and digital healthcare. Thu, 01 Oct 2026 00:00:00 GMT https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213326 2026-10-01T00:00:00Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/212891 Title: Jet-air excitation-based deep acoustic sensing for vehicle leakage detection Authors: Kim, Seon-Gyu; Park, Chanmin; Lee, Jongho; Park, Junhong; Kwak, Yunsang Abstract: This study presents an acoustic sensing framework for vehicle leakage detection based on jet-air excitation. Instead of relying on passive leakage signals, compressed air is actively directed toward potential leak regions, generating characteristic acoustic responses through fluid-structure interactions. A theoretical model is developed to predict resonance frequencies as functions of orifice geometry and jet parameters, including diameter and velocity. The model is validated through a series of controlled experiments using aluminum plate specimens with machined orifices, confirming its ability to accurately capture frequency-domain characteristics associated with varying leak sizes. The approach is further applied to vehicle body-in-white components, where locationspecific resonance patterns are observed under jet-air stimulation. These results demonstrate the sensitivity of the method to structural complexity and geometric variability. Full-vehicle experiments are conducted by introducing artificial leaks at representative regions, such as the windshield and trunk area, and measuring internal acoustic responses. The observed spectral features consistently distinguish leak conditions from non-leak baselines. A data-driven classification model is trained using spectral features extracted from the measured signals, enabling automated identification of leakage conditions. Overall, the proposed technique offers a physically grounded, non-contact, and scalable alternative to conventional inspection methods, with strong potential for integration into automated vehicle quality assurance processes. Tue, 01 Sep 2026 00:00:00 GMT https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/212891 2026-09-01T00:00:00Z