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홍성훈,김미현,윤혜원,Hong, S.H.,Kim, M.H.,Yun, H.W. 한국전자통신연구원 2017 전자통신동향분석 Vol.32 No.6
A metamaterial is a material engineered to have a property that does not exist in nature. A designable material property can be achieved by tailoring its structure, and thus a metamaterial is a novel ICT material and component technology that can break through the limitations of conventional technologies. Among the metamaterials available, a perfect metamaterial absorber is a technology that can nearly absorb light, sound waves, thermal waves, and electromagnetic waves with a simple structure, and has been of significant interest in energy, display, sensor, stealth, and military applications, with wavelengths from visible light to microwaves. In this article, we introduce a brief description of metamaterial absorber technology, the critical issues for its application, as well as ETRI's developed metamaterial absorber technology and its prospects for future use.
정영래(Y. R. Jung),박원규(W. G. Park),박영준(Y. J. Park),김종섭(J. S. Kim),홍성훈(S. H. Hong) 한국전산유체공학회 1997 한국전산유체공학회지 Vol.2 No.1
The flow field around a three dimensional minivan-like body has been simulated. This study solves 3-D unsteady incompressible Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using second-order accurate schemes for the time derivatives, and third/second-order scheme for the spatial derivatives. The Marker-and-Cell concept is applied to efficiently solve continuity equation. A H-H type of multi-block grid system is generated around a three dimensional miuivan-like body, Turbulent flows have been modeled by the Baldwin-Lomax turbulent model. To validate present procedure, the flows around the Ahmed body with 12.5' of slant angle are simulated. A good agreement with other numerical results is achived. After code validation, the flows around a mimivan-like body are simulated. The simulation shows three dimensional vortex-pair just behind body. The flow separation is also observed on the rear of the body. It has concluded that the results of present study properly agreed with physical flow phenomena.
정영래(Y. R. Jung),박원규(W. G. Park),박영준(Y. J. Park),김종섭(J. S. Kim),홍성훈(S. H. Hong) 한국전산유체공학회 1997 한국전산유체공학회지 Vol.2 No.1
The flow field around a three dimensional minivan-like body has been simulated. This study solves 3-D unsteady incompressible Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using second-order accurate schemes for the time derivatives, and third/second-order scheme for the spatial derivatives. The Marker-and-Cell concept is applied to efficiently solve continuity equation. A H-H type of multi-block grid system is generated around a three dimensional miuivan-like body, Turbulent flows have been modeled by the Baldwin-Lomax turbulent model. To validate present procedure, the flows around the Ahmed body with 12.5' of slant angle are simulated. A good agreement with other numerical results is achived. After code validation, the flows around a mimivan-like body are simulated. The simulation shows three dimensional vortex-pair just behind body. The flow separation is also observed on the rear of the body. It has concluded that the results of present study properly agreed with physical flow phenomena.
탄소중립과 디지털전환에 대응하는 농업용 UGV의 특허분석
홍성훈(S. H. Hong),신대영(D. Y. Shin),이철희(C. H. Lee),이용혁(Y. H. Lee) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.12
Diesel engines, which have been used as major power sources for agricultural machinery, have large low-speed torque, are resistant to moisture, and have simple structures such as no ignition system, which have few failures and advantages in maintenance. However, major developed countries around the world are gradually strengthening their drive for decarbonization through energy transition for carbon neutrality, agricultural machinery cannot be an exception to this trend. Along with the power source of eco-friendly agricultural machinery for decarbonization, autonomous platform based on digital transformation technology is also emerging as an important core technology. In this paper, published and granted patents since 2001 were analyzed to analyze the power sources of agricultural machinery and technology trends related to digital transformation. The classification was divided into digital transformation, special-purpose mobile platform, and low-and-zero carbon technology, and each technology was subsequently divided into three to four detailed technologies. This analysis targeted the US, Japan and Europe along with Korea, and major competitors of each target country were also analyzed. As a result, target technologies were analyzed in the early development stage from the perspective of the technology growth stage. Therefore, related R&D investment are required to secure global competitiveness and lead related markets.
홍성훈(S. H. Hong),안덕찬(D. C. Ahn),김광육(K. Y. Kim),김영석(Y. S. Kim) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.10
Tensile tests are used to clarify the basic mechanical properties of tested specimens and the obtained stress-strain relation gives important information for plastic flow under metal forming processes, i.e. formability and anisotropic properties. The specimen size, test procedure and data measurement method are specified under tensile test standards in order to assure reliability of the tested data. However, many various tests are performed in industrised, universities and research institutes for their convenience in reality. In this study we performed tensile tests according to the different test method and compared their results. These finding will contribute the understanding of each test method.
홍성훈(S. H. Hong),안덕찬(D. C. Ahn),김영석(Y. S. Kim) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.10
A fuel cell car has been noted next generation automobile. Recent research focused on fuel cell which is the main part of fuel cell cars. Use of thinner stainless steel sheets in bi-polar plate can reduce the weight and volume of the fuel cell. There are various standards to get into the basic mechanical properties of material, but not in the case of thin sheet metal is not clarified. To get an exact mechanical property is important to evaluated formability of thin stainless steel sheets. In this study, we performed tensile test, erichsen test to evaluate the formability of thin stainless steel sheets. It is difficult to mount a strain gauge on the thin sheet metal due to its weight. To improve the reliability of the tensile test, a CCD camera was used for calculation deformation. Erichsen test is a cupping test to measure the ductility of a sheet metal and to determine its suitability for deep drawing. However, more than 0.1mm thickness material is used as the test apparatus. Erichsen spherical punch diameter of 8.0mm~20.0mm, that is not good for the sheet metal as thin as 0.075 to 0.15mm thickness, In the case of thin sheet metal small punch diameter is needed for experiment.
나노임프린트 리소그래피를 이용한 곡면 기판 위에 정렬된 나노 볼 패턴 형성에 관한 연구
홍성훈(S. H. Hong),배병주(B. J. Bae),곽신웅(S. U. Kwak),이헌(H. Lee) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.6
The replica of highly ordered nano-sphere array patterns were fabricated using hot embossing method. First, silica nano-sphere array on Si substrate was transferred to PVC f ilm at 130℃ and 7 bar using hot embossing process. Then, silica nano-sphere array on PVC template was removed by soaking the PVC film in buffered oxide etcher. In order to form anti-stiction layer, the PVC template was coated with silicon dioxide layer and self-assembled monolayer. Through UV nanoimprint lithography with the fabricated flexible PVC template, highly ordered nano-sphere array pattern was imprinted on curved substrates with high fidelity.
홍성훈(S. H. Hong),이승욱(S. J. Lee),누엑늑뚜안(D. T. Nguyen),김갑득(G. D. Kim),송성훈(S. H. Song),김영석(Y. S. Kim) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
The incremental sheet forming (ISF) method is known as valuable tools to make a rapid prototype which can be observed the forming shape and also able to re-design the part based on the requirements. In this study, we have applied the ISF to prototype of walkway and stair step used in factories and architecture fields. CAD model of walkway and stair step is initially designed and imported to CAM software to model and generate G-code files. These files are imported to CNC machine to make a female die and subsequently producing the prototype of walkway and stair step by using the ISF. The major safety requirement is to avoid permanent deflection due to low stiffness and the slip of passenger while walking on the metal walkway. If the part is not able to satisfy given requirements, then the design should be modified. After we got experience with more trial, the best shape, which was obtained by incremental sheet forming process, will be applied to actual manufacturing of walkway and stair step by punching and stamping process.