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MEMS 기반 안전 소자에 대한 액정 폴리머 패키지의 밀폐도 연구
최진일 ( Jinnil Choi ),김용국 ( Yong Kook Kim ),주병권 ( Byeong Kwon Ju ) 한국센서학회 2015 센서학회지 Vol.24 No.5
Liquid crystal polymer (LCP) is a thermoplastic polymer with superior mechanical and thermal properties. In addition, its characteristics include very low water absorption rate and possibility to apply bonding process under low temperature. In this study, LCP is utilized as a packaging material for a microelectronic system (MEMS) based safety device with suggestion of a low temperature packaging process. Highly sensitive and stable capacitive type humidity sensor is fabricated to investigate hermeticity of the packaged MEMS device.
전현지,최진일,Jeon, Hyunji,Choi, Jinnil 한국재료학회 2020 한국재료학회지 Vol.30 No.12
Irradiation of the metal nanoparticles causes local plasmon resonance in a specific wavelength band, which can improve the absorption and scattering properties of a structure. Since noble metal nanoparticles have better resonance effects than those of other metals, it is easy to identify plasmonic reactions and this is advantageous to find the optical tendency. Compared to having a particle gap or randomly arranged particle structures, densely and evenly packed structures can exhibit more uniform optical properties. Using the uniform properties, the structure can be applied to optical filtering applications. Therefore, in this paper, validation tests about metal nanoparticles and thin film structures are conducted for more accurate analysis. The optical properties of monolayer and bilayer noble metal nanoparticle structures with different diameters, packed in a uniform array, are investigated and their optical trends are analyzed. In addition, a thin film structure under identical conditions as metal nanoparticle structure is evaluated to confirm the improved optical characteristics.
Fe-Si-Al-Graphite 분말 혼합체의 압축 특성 연구
정준혁,최진일,Jeong, Jun Hyeok,Choi, Jinnil 한국분말야금학회 2020 한국분말재료학회지 (KPMI) Vol.27 No.4
In this paper, a durability study is presented to enhance the mechanical properties of an Fe-Si-Al powder-based magnetic core, through the addition of graphite. The compressive properties of Fe-Si-Al-graphite powder mixtures are explored using discrete element method (DEM), and a powder compaction experiment is performed under identical conditions to verify the reliability of the DEM analysis. Important parameters for powder compaction of Fe-Si-Al-graphite powder mixtures are identified. The compressibility of the powders is observed to increase as the amount of graphite mixture increases and as the size of the graphite powders decreases. In addition, the compaction properties of the Fe-Si-Al-graphite powder mixtures are further explored by analyzing the transmissibility of stress between the top and bottom punches as well as the distribution of the compressive force. The application of graphite powders is confirmed to result in improved stress transmission and compressive force distribution, by 24% and 51%, respectively.
Design of the Structural Connection for Lightweight Structure Application
남병현,최진일,Nam, Byung Hyun,Choi, Jinnil The Korea Society for Simulation 2020 한국시뮬레이션학회 논문지 Vol.29 No.2
본 논문에서는 경량구조 적용을 위한 구조 접합부 설계를 제시하였다. 압력에 대한 구조 안정성 연구를 위하여 용접부 접합부와 볼트 접합부에 대한 모델을 설계하였다. 확립된 모델의 신뢰성 검증을 위하여, 비선형 해석을 수행하였고, 실험결과와 비교하였을 때 유사한 결과를 확인하였다. 또한 비교연구를 통하여 구조설계 재료와 적합한 용접방법을 선택하였으며, 볼트의 개수와 위치에 따른 파단하중 시뮬레이션을 진행하여 응력에 따른 안정성을 분석하였다. 마지막으로, 접합부 모델을 기반으로 경량 구조를 모델링하고 구조 해석을 수행하였다. 그 결과, 용접부와 볼트체결을 적용하여 설계된 구조가 접합부를 적용하지 않은 구조에 비해 최대응력이 31.4% 감소함을 확인하였다. 이 결과를 토대로, 경량구조의 안정성 해석 시 접합부 모델링의 필요성을 확인하였다. The structural connection design for lightweight structure application is presented in this paper. Modeling of the welding zone and the bolted connection are suggested. For reliability verification of the established models, nonlinear analysis is performed and comparisons are made with the experimental data showing good agreement. Through comparison study, suitable welding method for structure materials is investigated. Also, stability analysis is performed by fracture load simulation for different number and position of bolts. Finally, based on the structural connection models, the lightweight structure is modeled and structural analysis was performed. Stability analysis of structural connection for lightweight structure design, through combination of welding and bolting process, showed a 31.4% decrease in the maximum stress compared to the structure without the structural connections. Importance of structural connection design is highlighted for lightweight structure stability analysis.
유한요소법을 이용한 유연소자용 Au 나노구조체의 내구성 평가
남병현(Byung Hyun Nam),윤홍석(Hongseok Youn),최진일(Jinnil Choi) 한국생산제조학회 2021 한국생산제조학회지 Vol.30 No.1
In this study, the levels of durability of nanostructures for flexible devices are explored based on tensile force, bending moment, and torsion. First, for application to optical devices, aluminium nanostructures are fabricated using laser interference lithography. The optical characteristics of the fabricated nanopatterns are investigated, and the structure with the highest light transmittance is selected for durability analysis. A structural analysis model using the finite element method is then developed and its reliability is validated through a comparison with the experimental data for both polyethylene terephthalate and Au thin films. Finally, the different levels of durability of the nanostructures are investigated for application based on tensile force, bending moment, and torsion. The structural weakness of each nanostructure is explored and the durability characteristics are highlighted.
박승병(Seung Byung Park),이상혁(Sang-Hyeok Lee),최진일(Jinnil Choi),최종민(Jong Min Choi) 한국지열·수열에너지학회 2015 한국지열에너지학회논문집 Vol.11 No.4
The efficiency, reliability and performance of any heat pump unit can only be ascertained after it has been tested and rated. For this reason, specific facilities, equiped with testing plants are built. Heat pump calorimeter is the facilities used by most of these testing facilities in their rating and certification process. The ultimate function of calorimeters is to, control and maintain the constant standard test conditions (indoor/outdoor entering temperatures and flow rate etc) during testing period. In this study, the test standards of heat pump unit and the structure of the calorimeter are surveyed. In addition, this study analyzes the total energy consumption of a water to water heat pump calorimeter. Heat pump calorimeter consumed much energy to excute the heat pump tests. The energy consumption of the calorimeter was higher than the heat pump unit, and it was increased as the heat pump unit capacity decreased.