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Fabrication Methods for Microscale 3D Structures on Silicon Carbide
Younghak Cho,Jihong Hwang,Min-Soo Park,Bo Hyun Kim 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.12
Silicon carbide (SiC) is an attractive material for many industrial applications, such as semiconductors, electronic power devices, and optical and mechanical devices, owing to its wide bandgap, high thermal and wear resistance, and chemical inertness. Although SiC has superior properties, fabricating micro-features on SiC is very expensive and time-consuming. Many studies have introduced various fabrication methods utilizing physical, chemical, and thermal principles to remove SiC material. This paper reviews the state-of-the-art processes applicable for fabricating micro-3D structures on SiC, including etching, mechanical, thermal, and additive processes. The advantages and limitations of these processes are also discussed to guide the selection of processes suitable for SiC.
A Design of a 3-Dimensional Disaster Prevention Map to Express Underground Facilities
Younghak Chun,Shinil Jung,Changsoo Kim 한국멀티미디어학회 2010 한국멀티미디어학회 국제학술대회 Vol.2010 No.-
Modem society has intensively developed around metropolis. It is necessary to develop underground space as well as skyscrapers on the ground because people living in the various societies want to be satisfied with their demand in the limited space. As the underground space is expanded, more houses and stores are concentrated in metropolitan area. Then, the metropolitan have had an opportunity for high-density growth. However, disasters in the underground space are more horrible than those on the ground, so have caused the heavy casualties. One of the reasons can be regarded as unknowing of its location and the entrance of exits as well as the absence of disaster prevention facilities. In this study, we propose a design of a 3-dimensional disaster prevention map based on the smart phones to provide detail information of facilities and the direction of emergency exits.
Younghak Cho,Beomjoon Kim,Seokkwan Hong,Jeongjin Kang 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.3
This paper deals with a novel structure for single-cell characterization which makes use of bimorph micro thermal actuators combined with electrical sensor device and integrated microfluidic channel. The goal for this device is to capture and characterize individual biocell. Quantitative and qualitative characteristics of bimorph thermal actuator were analyzed with finite element analysis methods. Furthermore, optimization for the dimension of cantilevers and integrated parallel systems with microfluidic channels is able to be realized through the virtual simulation for actuation and the practical fabrication of prototype of probes. The experimental value of probe deflection was in accordance with the simulated one.
L1-norm Minimization based Sparse Approximation Method of EEG for Epileptic Seizure Detection
Younghak Shin,성진택 한국정보전자통신기술학회 2019 한국정보전자통신기술학회논문지 Vol.12 No.5
Epilepsy is one of the most prevalent neurological diseases. Electroencephalogram (EEG) signals are widely used for monitoring and diagnosis tool for epileptic seizure. Typically, a huge amount of EEG signals is needed, where they are visually examined by experienced clinicians. In this study, we propose a simple automatic seizure detection framework using intracranial EEG signals. We suggest a sparse approximation based classification (SAC) scheme by solving overdetermined system. L1-norm minimization algorithms are utilized for efficient sparse signal recovery. For evaluation of the proposed scheme, the public EEG dataset obtained by five healthy subjects and five epileptic patients is utilized. The results show that the proposed fast L1-norm minimization based SAC methods achieve the 99.5% classification accuracy which is 1% improved result than the conventional L2 norm based method with negligibly increased execution time (42msec).
이영학 ( Younghak Lee ),이달원 ( Dalwon Lee ),김철한 ( Cheolhan Kim ),홍석민 ( Seokmin Hong ) 한국농공학회 2017 한국농공학회 학술대회초록집 Vol.2017 No.-
본 연구에서는 노후화된 농업용저수지의 효율적인 리모델링 방법을 제시하기 위하여 코어와 필터가 없거나 노후화 되어 기능을 하지 못하는 균일형 저수지의 상류사면을 보강하였을 경우에 실내모형실험을 통하여 공극수압과 토압 거동을 비교분석하였다. 코어와 필터가 없는 균일형 제체(Case-1)에서의 공극수압은 만수위 상태까지 급격히 상승하였고, 필터를 보강한 경우(Case-2)는 반응속도가 느리고 약간씩 증가하였으며, 상류사면을 보강한 경우(Case-3)는 매우 느리고 작은 값을 나타냈다. 준설토를 이용한 상류사면의 리모델링 방법은 코어와 필터가 노후화되어 차수기능과 침투기능을 하지 못하기 때문에 1차적으로 코어를 설치하여 침투수를 차단하고, 누수된 침투수는 하류사면의 필터를 통하여 신속하게 배출시켜 파이핑 현상에 대한 안정성을 높일 수 있고 아울러 저수지의 내용적을 증가시키는 매우 효율적인 리모델링 방법이라고 판단된다. 코어와 필터가 없는 균일형 제체(Case-1)의 상류사면을 준설토로 리모델링한 경우(Case-3)에 상류사면 토압과 성토 중앙부의 토압은 수위가 증가함에 따라 급격하게 증가하고 일정한 상태를 나타냈다. Case-3의 경우가 Case-1보다 약간 더 크게 나타났고, 하류사면에서는 모든 경우에서 큰 변화 없이 유사한 값을 나타냈다. 상류사면의 토압이 성토 중앙부에서 측정한 값보다 크고 하류사면의 토압은 작기 때문에 아칭현상은 발생되지 않았으며, 상류사면의 공극수압은 같은 위치의 토압보다 약간 작거나 유사하게 나타나 수압할렬의 가능성이 없는 것으로 나타났다.