https://scholar.gist.ac.kr/handle/local/7954 2026-08-07T07:52:02Z 2026-08-07T07:52:02Z Jihyeon Lim https://scholar.gist.ac.kr/handle/local/33863 2026-03-03T05:21:49Z 2025-12-31T15:00:00Z

Title: 국부 저압화 플라즈마 장치의 개발 및 플라즈마를 이용한 접착 강도 향상 Author(s): Jihyeon Lim Abstract: Plasma-assisted surface modification is widely recognized as an effective method for improving adhesion strength. However, conventional plasma systems face critical limitations. Low-pressure plasma systems achieve significant adhesion improvements but require prolonged pumping times, sample-size restrictions, and vacuum chambers, whereas atmospheric-pressure systems enable faster processing but exhibit limited adhesion improvements. To overcome these constraints, a Localized Low-pressure Plasma Device (LLPD) is developed, which integrates the advantages of both systems—strong plasma treatment and rapid processing. Unlike traditional low-pressure plasma systems that require placing the sample inside a sealed chamber, the LLPD enables direct plasma generation on the material surface by attaching the device externally, offering a compact, mobile, and scalable treatment configuration. The design of LLPD features localized evacuation and stable low-pressure plasma generation, achieving efficient radical formation within seconds. The production of highly reactive atomic oxygen species was confirmed using optical analysis under these conditions, which play a crucial role in surface functionalization. The performance of the LLPD was validated through plasma treatment of carbon fiber reinforced thermoplastic polymer (CFRTP), where rapid and robust adhesion enhancement was achieved within 20 seconds—comparable to the strongest reported results for conventional low-pressure plasma systems but at a fraction of the processing time. The development of LLPD establishes a new pathway for high-throughput, on-site plasma surface treatment without the need for massive vacuum chambers. LLPD thus represents a highly versatile and industrially compatible plasma source, particularly suited for large-scale structures in the aerospace and automotive industries.

2025-12-31T15:00:00Z Jang Minwoo https://scholar.gist.ac.kr/handle/local/33862 2026-03-03T05:21:48Z 2025-12-31T15:00:00Z

Title: 거대 열팽창 단결정 소재 기반 고내구성 초박막 바이모프 엑추에이터의 설계 및 제작 연구 Author(s): Jang Minwoo Abstract: 거대 열팽창(colossal thermal expansion, TE) 특성을 보이는 동적 결정체(dynamic crystals)는 큰 부피 변화와 선형적인 열 응답성을 지니고 있어, 차세대 스마트 액추에이터(예: 인공 근육, 오리가미 시스템, 소프트 로보틱스)의 유망한 후보로 주목받고 있다. 그러나 단결정성 을 유지하면서 소재를 가공하고 대면적으로 확장(scale-up)하는 데에는 여전히 어려움이 존재한 다. 이의 결과로 기존 동적 결정체들은 취성에 약하고 거시적인 환경에서의 사용이 어려우며 우 연에 의존하는 움직임을 기대할 수 밖에 없다. 이에 본 연구에서는 능동층으로 6,13-비스(트라 이아이소프로필실릴에티닐)펜타센(6,13-bis(triisopropylsilylethynyl)pentacene, TIPS-P) 단결 정 필름을, 수동층으로 SU-8 을 사용한 열응답형 바이모프 액추에이터를 제시한다. 메니스커스 유도 프린팅(meniscus-guided printing) 기술을 통해 TIPS-P 필름의 결정학적 배향을 본질적 으로 정렬시킬 뿐 아니라 형태적 설계가 가능하다. 그 결과 제작된 액추에이터는 프로그래머블한 거동을 보이며 거대 열팽창 계수(425.3 MK-1)를 갖으며 높은 영률(3 GPa)을 갖는 TIPS-P 의 특 성에 기인하여 높은 곡률(6.7–10.8 cm-1)을 나타냈다. 또한, 이 액추에이터는 3.27 × 10-7 J 에서 5.6 × 10-7 J 범위의 기계적 일을 발생시키는 성능을 보였다.|Dynamic crystals exhibiting colossal thermal expansion (TE) show large volumetric changes and linear thermal responsiveness, making them promising candidates for next-generation smart actuators such as artificial muscles, origami systems, and soft robotics. However, maintaining single crystallinity during processing and achieving large-area scale-up remain significant challenges. As a result, conventional dynamic crystals often suffer from brittleness, limited applicability in macroscopic environments, and motion that relies heavily on chance rather than deterministic control. In this study, we present a thermally responsive bimorph actuator composed of a single-crystalline 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-P) film as the active layer and SU-8 as the passive layer. The meniscus-guided printing technique enables intrinsic crystallographic alignment of the TIPS-P film while allowing precise morphological design. Consequently, the fabricated actuator exhibits programmable motion and achieves high curvature (6.7–10.8 cm⁻¹), attributed to the colossal thermal expansion coefficient (425.3 MK⁻¹) and relatively high Young’s modulus (~3 GPa) of TIPS-P. Furthermore, the actuator delivers mechanical work in the range of 3.27 × 10⁻⁷ J to 5.6 × 10⁻⁷ J.

2025-12-31T15:00:00Z Chelim Jang https://scholar.gist.ac.kr/handle/local/19897 2025-06-30T12:13:15Z 2022-12-31T15:00:00Z

Title: Window-film Type Semitransparent Organic Photovoltaics Based on Conducting Polymer Electrodes for Building-integrated Photovoltaics Author(s): Chelim Jang Abstract: Semitransparent organic photovoltaics (ST-OPVs) with polymeric transparent electrodes are in the spotlight as window film type solar cells due to their advantages such as flexibility, high electrical conductivity, transparency, and solution processability. Currently, encouraging progress has been achieved on the ST-OPVs that focus on individual parameters such as high power conversion efficiency (PCE) and average visible transmittance (AVT), however, the passive properties as window films are yet to be explored. Furthermore, conventional transparent electrodes based on a vacuum process are expensive and possess poor productivity. Herein, we demonstrate all-solution processed multifunctional ST-OPVs using PEDOT (poly(3,4-ethylene dioxythiophene)) as a top electrode doped with perfluorinated sulfonic acid. Importantly, the perfluorinated sulfonic acid-treated PEDOT electrode exhibits high visible transmittance and outstanding electrical properties and simultaneously showed high infrared reflectance. Consequently, we successfully achieved high light utilization efficiency and thermal insulating capability.

2022-12-31T15:00:00Z Daun Seo https://scholar.gist.ac.kr/handle/local/33860 2026-03-03T05:21:47Z 2025-12-31T15:00:00Z

Title: Wet tissue adhesive self-gelling polymeric powder hydrogels for rapid hemostasis Author(s): Daun Seo Abstract: Acute hemorrhage frequently occurs during trauma or surgical procedures, and insufficient hemostatic control can lead to severe complications or mortality. Conventional hemostatic agents, such as fibrin glue and pre-formed hydrogels, often exhibit limited efficacy in wet and bleeding environments due to their loss of adhesion and difficulties in handling. To address these limitations, I developed a self-gelling polymeric powder hydrogel composed of dextran-aldehyde and gelatin to permit rapid hemostasis through strong wet-tissue adhesion. The powder undergoes rapid in situ gelation through Schiff base reactions between the aldehyde groups of dextran-aldehyde and the amino groups of gelatin, enabling strong wet tissue adhesion. The dex-ald/gelatin powder hydrogel exhibited robust tissue adhesion to various wet tissues, including skin (14.5 ± 2.2 kPa), epicardium (10.7 ± 3.1 kPa), and muscle (9.1 ± 3.6 kPa), and demonstrated superior sealing performance in a porcine intestine model compared to fibrin glue, achieving a high bursting pressure of 10.4 ± 1.3 kPa. Furthermore, in vitro hemolysis and blood clotting confirmed its excellent hemocompatibility and effective promotion of clot formation. These findings suggest the potential of this polymeric powder hydrogel as a next-generation hemostatic sealant for surgical and emergency applications.

2025-12-31T15:00:00Z