다중벽 탄소나노튜브의 형상인자에 따른 고분자 복합재료의 탄성계수에 관한 연구

서종환(Jonghwan Suhr) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.1

탄소나노튜브는 우수한 기계적 특성으로 인해 주목받고 있으며, 다양한 산업 분야로의 잠재적 활용성을 갖는 고강도/고강성의 나노복합재료를 설계/제작하기 위한 다양한 연구가 이루어 지고 있다. 본 논문에서는 다중벽 탄소나노튜브를 이용한 강화 복합재료를 효과적으로 설계하고, 기계적 물성을 예측/평가하기 위한 미시역학적 해석 방법 연구를 수행하였다. 이를 위해 먼저 대표체적요소 모델을 설계하고 이를 이용한 유한요소 해석을 통해서 강화 복합재료의 기계적 물성을 평가하였다. 특히 MWCNT 의각 형상인자에 따른 복합재료의 탄성계수 변화를 예측하고, 각 인자들의 영향을 정성적으로 평가하였다. 더불어 형상인자들의 복합적 조건에서의 탄성계수에 대한 영향 평가도 수행하였다. The high Young"s modulus and tensile strength of carbon nanotubes has attracted great attention from the research community given the potential for developing super-strong, super-stiff composites with carbon nanotube reinforcements. Over the decades, the strength and stiffness of carbon nanotube?reinforced polymer nanocomposites have been researched extensively. However, unfortunately, such strong composite materials have not been developed yet. It has been reported that the efficiency of load transfer in such systems is critically dependent on the quality of adhesion between the nanotubes and the polymer chains. In addition, the waviness and orientation of the nanotubes embedded in a matrix reduce the reinforcement effectiveness. In this study, we carried out performed micromechanicsbased numerical modeling and analysis by varying the geometry of carbon nanotubes including their aspect ratio, orientation, and waviness. The results of this analysis allow for a better understanding of the load transfer capabilities of carbon nanotube?reinforced polymer composites.

자기-아핀 표면 특성을 고려한 유기탄성체 복합재료 마찰 이론 및 타이어 트레드/노면 마찰 응용

윤범용,장윤진,김백환,서종환,Bumyong Yoon,Yoon Jin Chang,Baekhwan Kim,Jonghwan Suhr 한국복합재료학회 2023 Composites research Vol.36 No.3

This review paper presents an introduction of contact mechanics and rubber friction theory for sliding friction of elastomer composites in contact with rough surfaces. Particularly, Klüppel & Heinrich theory considers the self-affine (or fractal) characteristic for rough surfaces to predict adhesion and hysteresis frictions of elastomers based on the contact mechanics of Greenwood & Williamson. Due to dynamic excitation process of elastomer composites while sliding in contact with multiscale surface roughness (or asperity), viscoelastic properties in a wide frequency range becomes major contributor to friction behaviors. A brief description and examples are provided to construct a viscoelastic master curve considering nonlinear viscoelasticity of elastomer composites. Finally, application of rubber friction theory to tire tread compounds in traction with road surfaces is discussed with several experimental and theoretical results.

3D 프린터용 복합재료 연구 동향

오은영 ( Eunyoung Oh ),이진우 ( Jinwoo Lee ),서종환 ( Jonghwan Suhr ) 한국복합재료학회 2018 Composites research Vol.31 No.5

3D 프린팅 기술의 활용은 복잡한 형상의 제품을 보다 손쉽게 생산 가능하게 하며, 시간적·경제적 이점을 제공함으로써 기존 제조업의 형태를 변화시킬 차세대 핵심 제조 기술로 부상하고 있다. 그러나 순수 고분자 소재출력물의 기계적/전기적 특성 및 기능은 해당 기술의 확산에 있어 한계점으로 작용하였고, 이것은 고성능 고분자 복합재료 개발에 대한 수요로 이어졌다. 이에 본 논문에서는 고성능 3D 프린팅용 고분자 복합재료 개발의 최신연구 동향을 소개하고, 응용 분야와 가능성 및 향후 연구방향에 대해 논하고자 한다. The use of 3D printing for rapid tooling and manufacturing has promised to produce components with complex geometries according to computer designs and it is emerging as the next generation key of manufacturing. Due to the intrinsically limited mechanical/electrical properties and functionalities of printed pure polymer parts, there is a critical need to develop 3D printable polymer composites with high performance. This article gives a review on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the various fields.

상변화물질을 이용한 PMMA 복합필름의 방열 성능 향상에 관한 연구

권준혁,윤범용,조승현,김형익,김동현,박경의,서종환,Kwon, Junhyuk,Yoon, Bumyong,Cho, Seung-hyun,Lee, Stephanie K.,Kim, Hyung-ick,Kim, Donghyun,Park, Kyungui,Suhr, Jonghwan 한국복합재료학회 2017 Composites research Vol.30 No.5

본 연구에서는 전자기기 사용에 이슈가 되고 있는 발열 문제를 해결하고자 상변화물질(PCM)의 잠열 특성을 이용하여 폴리메틸메타크릴레이트(PMMA) 복합필름을 제조하고 방열 성능을 평가하였다. 이를 위해 용융온도가 서로 다른 두 가지의 상변화물질을 사용하여 제작한 PCM/PMMA 복합필름의 열적 특성을 비교 분석하여 다양한 사용조건에 따른 유효성을 검증하였고, Compression Molding 방법과 PCM Paste Sealing 방법에 따른 PCM/PMMA 복합필름의 방열 특성을 비교 분석하여 최대의 방열 효과를 달성할 수 있는 최적의 방법을 도출하였다. 또한 PCM/PMMA 복합필름의 방열 성능을 최대화하기 위해 열전도율이 높은 흑연과 그래핀을 추가로 적층하여 제조한 Hybrid 복합필름의 열적 특성을 분석하였고, 이들을 통해 향상된 방열 성능을 실험적으로 검증하였다. 본 연구를 통해 개발된 방열 성능이 우수한 복합필름은 다양한 전자기기에 활용되어 발열 문제를 효과적으로 해결할 수 있을 것으로 기대된다. The focus of this study is to experimentally investigate the heat dissipation characteristics of poly (methyl methacrylate) (PMMA) composite films with phase change materials (PCM) to resolve heat build-up problems encountered in various electronic devices. In this study, two different types of phase change materials were used to fabricate the composite films by compression molding method and PCM paste sealing method then compared. It was observed in this study that the heat dissipation capability of PCM/PMMA composite films was remarkably enhanced by applying graphite sheet or graphene film into the composite due to their high thermal conductivity. These PCM/ PMMA composite films were attached on the hot spot inside smart phone and tested its surface temperature change according to time. The heat dissipation capability of PCM/PMMA composite film incorporated smart phone was increased 154% and hybrid PCM/PMMA composite film incorporated smart phone was increased 286% over the reference, respectively.

차세대 자동차용 친환경 복합재료의 동향 및 전망

오은영 ( Eunyoung Oh ),( Marcela Maria Godoy Zuniga ),서종환 ( Jonghwan Suhr ) 한국복합재료학회 2024 Composites research Vol.37 No.2

환경에 대한 범세계적인 문제와 관심이 고조되는 가운데 자동차 산업에서도 친환경 소재로의 전환이 가속화되고 있다. 자동차 산업에서 친환경 복합재료는 차량 내부 및 비 구조 부품에 주로 사용된다. 특히 천연섬유 복합재료는 차량의 경량화로 연료 소비와 온실가스 배출을 줄이는데 도움을 주며 재활용이 가능하고 우수한 열적 특성과 내구성을 가지고 있어 자동차 내장 부품에 적합하다. 아울러 생산 비용 절감과 지속 가능성은 천연섬유 복합재료의 주요 장점이다. 친환경 복합재료 시장은 2022년부터 2030년까지 연평균 성장률 15.3%로 864억 3천만 달러 규모로 성장할 것으로 기대되며, 천연섬유 복합재료 시장은 2023년부터 2028년까지 연평균 5.3% 성장해 4억 2,400만 달러에 이를 것으로 예상된다. 본 리뷰 논문에서는 천연섬유 복합재료를 중심으로 차세대 자동차용 친환경 복합재료의 연구 동향과 실제 자동차 산업에서의 적용에 대해 탐구한다. As global issues and interest in the environment increase, the transition to eco-friendly materials is accelerating in the automobile industry. In the automotive industry, eco-friendly composite materials are mainly used in various interior and exterior components, reducing the reliance on traditional petroleum-based materials. In particular, natural fiber composites help reduce fuel consumption and greenhouse gas emissions by making vehicles lighter. Additionally, they boast superior thermal properties and durability compared to non-recyclable composite materials, making them suitable for automotive interior parts. Furthermore, reduced production costs and sustainability are key advantages of natural fiber composites. The eco-friendly composites market is expected to grow to $86.43 billion at a CAGR of 15.3% from 2022 to 2030, and the natural fiber composites market is predicted to grow at a CAGR of 5.3% from 2023 to 2028 to $424 million. In this review paper, we explore research trends in nextgeneration natural fiber composite materials for automobiles and their application in the actual automobile industry.

Taguchi based parameters optimization for tensile strength and print time for fused deposition modelling

Tran Trung Tien,Jinwoo Lee(이진우),Jonghwan Suhr(서종환) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6

Additive manufacturing (AM) defined as the method of building parts by adding material in layer-by-layer fashion to create an object. Fused deposition modeling (FMD) is a subset of AM using filament shaped thermoplastic polymer the material, computer aided design model then analyzed by the program and command are send to the 3D printer for building the model. Ease of use is the main strong point that make 3D printing become the rapid prototyping for industrial application and for hobbies or school teaching. FDM 3D printed structures can be used in automobile industry in application that required low volume high complexity part, but 3D printed part suffered low mechanical properties, highly anisotropic mechanical strength, low reliabilities due to imperfection. Therefore, research is needed to best taking advantages of 3D printing and increase parts reliabilities so more and more 3D printed part can be implemented in real world uses in the future. Tensile strength and print time are the two properties that get the most attention when using FDM printing to make part since it will decide whether or not the designed parts are suitable 3D printing. Build orientation, layer thickness, print speed and other overlooked printing parameters can influence tensile strength and print time drastically. Experiments are conducted to find the most affective parameters to each response properties, the result is later interpreted to optimize the print process for each response (faster print time or stronger part). However, considering many parameters and level in each parameter will increase the number of experiments exponentially. Taguchi experiment design method and Analysis of variance (ANOVA) are widely used not only to reduces the amount of experiment needed, but also have the superior benefit of identifying the relationship between inputs parameters on each other. This experimental study will investigate the affect of 3D printing parameters on print time and part tensile strength, using Taguchi method to create the set of experiments and ANOVA to identify the optimal combination of parameters to achieve the desired property.

사용자 맞춤형 경도 조절이 가능한 시트 소재 연구

진보경(Bogyeong Jin),이진우(Jinwoo Lee),강경훈(Kyeonghoon Kang),최권용(Kwonyong Choi),서종환(Jonghwan Suhr) 한국자동차공학회 2022 한국자동차공학회 부문종합 학술대회 Vol.2022 No.6

바이오 폴리올을 사용한 Bio-PU foam 합성과 착좌감 가변형 자동차 시트로의 응용 연구

강경훈(kyeonghoon Kang),오태훈(Taehoon Oh),최권용(Kwonyong Choi),서종환(Jonghwan Suhr) 한국자동차공학회 2023 한국자동차공학회 학술대회 및 전시회 Vol.2023 No.11

적층형 메타 구조의 히트 싱크를 이용한 노트북 방열 성능 향상에 관한 수치 해석 연구

김재훈(Jae-Hoon Kim),양경태(Kyung Tae Yang),서종환(Jonghwan Suhr) 대한기계학회 2024 대한기계학회 춘추학술대회 Vol.2024 No.4

This study focuses on thermal analysis to optimize the heat dissipation system in high-performance laptops. As laptops become lighter and slimmer while their performance increases, the heat generated by the main board becomes significant. Efficiently removing this thermal energy to lower the laptops temperature is crucial in heat dissipation design. The high temperature from the CPU on the laptops motherboard is transferred to the heat sink via a heat pipe, with heat being expelled through forced convection by a cooling fan. Optimizing the heat sinks design can significantly enhance the laptops performance and minimize heat generation. We applied a systemintegrated numerical analysis capable of predicting a laptops heating level and introduced a meta-structured heat sink fabricated using metal 3D printing to enhance heat dissipation, aiming to significantly reduce the laptops surface temperature. The findings of this study are expected to serve as a vital methodology for the development of high-performance laptops in the future.

PBF 3D프린팅으로 적층 제조한 17-4PH 스테인리스 강재의 열응력 및 열변형 연구

배재훈(Jae-Hoon Bae),김민겸(Min-Kyeom Kim),유상훈(Sang-Hoon Yoo),서종환(Jonghwan Suhr) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11