• 유체기계공업학회:학술대회논문집
• /
• 2002.12a
• /
• pp.482-485
• /
• 2002

Development projects in KAIST rotted to the micro thermal device is introduced. Multi disciplinary research team is composed by combustion group and semiconductor group in KAIST and catalyst research center in KRICT to develop micro thermal/fluidic device and various items are on development. Among the projects, various kind of componenst that is required by the micro thermal devicesystem is introduced. Technology related to development of micro combustor, Micro igniter, micro fabrication of 3D structure, micro reactor and micro catalyst preparation is introduced.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.934-937
• /
• 2001

It is well-known that the micro fabrication technology of micro parts are the high energy beam or silicon-based micro machining method such as LIGA Process, Laser machining, photolithography and etching technology. But, for fabricating complex 3-D structure it is better to use mechanical machining. This machining method by the mechanical machine tool with nanometer accuracy is getting attention in some field-especially micro optics machining such as grating, holographic lens, micro lens array, fresnel lens, encoder disk etc.. In this study, we survey the micro fabrication by mechanical cutting method and set up the mechanical micro machining system. And we carried out micro cutting experiments for micro parts with v-shape groove.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.85-88
• /
• 1995

Recently, the micro mold maching techining technology is developed by means of the mechanical and high energy beam process. It is possible to make the micro structure mold with high aspect ratio by the LIGA technology. This mode is used for mass production of plastic parts by the micro injection molding method. In this study, we intend to research on the basic technology of micro injection molding. As the result, we developed the injection molding technology for small column plastic parts which diameter is 500 .mu. m and 200 .mu. m respectively with wbout aspect ratio 20.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.9 s.186
• /
• pp.61-67
• /
• 2006

Sandwich structures, which are composed of a thick core between two faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. Accordingly, the usage of sandwich structure is very widely applied to the aircraft, the automobile and marine industry, etc., because of these advantages. In this paper, we have investigated the buckling protection of an inner structure plate and the useful corrugated configuration for contact, and the fabrication method of the inner structure plate for large area using the continuous molding process. Also, we have guaranteed the accuracy of the molding process through the micro corrugated mold fabrication and secured the accuracy and analyzed aspect properties of the inner structure plate fabricated for a large area using the partial mold process. We have compared molding simulation according to the aspect thickness of the corrugated configuration with the molding experiment results.

• Journal of Navigation and Port Research
• /
• v.33 no.9
• /
• pp.635-644
• /
• 2009

The optimum design of power yacht belongs to the nonlinear constrained optimization problems. The determination of scantlings for the bow structure is a very important issue with in the whole structural design process. The derived design results are obtained by the use of real-coded micro-genetic algorithm including evaluation from Lloyd's Register small craft guideline, so that the nominal limiting stress requirement can be satisfied. In this study, the minimum volume design of bow structure on the power yacht was carried out based on the finite element analysis. The target model for optimum design and local structural analysis is the bow structure of a power yacht. The volume of bow structure and the main dimensions of structural members are chosen as an objective function and design variable, respectively. During optimization procedure, finite element analysis was performed to determine the constraint parameters at each iteration step of the optimization loop. optimization results were compared with a pre-existing design and it was possible to reduce approximately 19 percents of the total steel volume of bow structure from the previous design for the power yacht.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.4
• /
• pp.242-248
• /
• 2014

We have five soil series of pan soils in South Korea out of 391 series: Gangreung, Bugog, Yeongog, Jangweon, and Pogog. Productivity decreases in pan soils as pan horizons impede percolation and capillary rise of water and interrupt root extension. This study was performed to investigate pedogenic processes of pan soils mainly located in footslope and river terrace by analyzing physicochemical properties and soil micro-morphology. Korean pan soils belong to Alfisols, Ultisols, or Inceptisols and have udic or aquic soil moisture regime, mesic temperature regime, and mixed mineral substances. Texture of pan horizons selected for the present study was mainly silty clay loam with clay contents ranging from 26.3 to 45.3%. Bulk density of the pan horizons ranged from 1.4 to $2.1Mg\;m^{-3}$ and their soil structure were subangular or angular structure. In terms of micro-morphological structure, Bt horizon of Gangreung series was formed as platy and striated b-fabric structure possibly affected by uplift of coastal terrace following clay sedimentation by flood. Jangweon series showed micro-morphology of massive structure and crystallic b-fabric as macropores between coarse debris established by debris fall in slope were filled with silt-sized particles. The Bt horizons having massive structure and striated b-fabric in Yeongog, Pogog, and Bugog series implies that those horizons experienced horizontal mass flow after clay accumulation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.111-114
• /
• 2005

Experimental and numerical studies were carried out in order to investigate the processability and the transcriptability of the injection molding of micro structures. For this purpose, we designed a mold insert having micro rib patterns on a relatively thick base part. Mold insert has a base of 2mm thickness, and has nine micro ribs on that base plate. Width and height of the rib are $300{\mu}m\;and\;1200{\mu}m$, respectively. We found a phenomenon similar to 'race tracking', due to 'hesitation' in the micro ribs. As the melt flows, it starts to cool down and melt front located in the ribs near the gate cannot penetrate further because the flow resistance is large in that almost frozen portion. When the base is totally filled, the melt front away from the gate is not frozen yet. Therefore, it flows back to the gate direction through the ribs. Consequently, transcriptability of the rib far from the gate is better. We also verified this phenomenon via numerical simulation. We further investigated the effects of processing conditions, such as flow rate, packing time, packing pressure, wall temperature and melt temperature, on the transcriptability. The most dominant factor that affects the flow pattern and the transcriptability of the micro rib is flow rate. High flow rate and high melt temperature enhance the transcriptability of micro rib structure. High packing time and high packing pressure result in insignificant dimensional variations of the rib. Numerical simulation also confirms that low flow rate causes a short shot of micro ribs and high wall temperature helps the filling of the micro ribs.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.05a
• /
• pp.131-132
• /
• 2012

• Computers and Concrete
• /
• v.2 no.3
• /
• pp.189-202
• /
• 2005

This paper presents an analysis of some experimental results concerning micro-structural tests, permeability measurements and strain-stress tests of four types of High-Performance Concrete, exposed to elevated temperatures (up to $700^{\circ}C$). These experimental results, obtained within the "HITECO" research programme are discussed and interpreted in the context of a recently developed mathematical model of hygro-thermal behaviour and degradation of concrete at high temperature, which is briefly presented in the Part 2 paper (Gawin, et al. 2005). Correlations between concrete permeability and porosity micro-structure, as well as between damage and cracks' volume, are found. An approximate decomposition of the thermally induced material damage into two parts, a chemical one related to cement dehydration process, and a thermal one due to micro-cracks' development caused by thermal strains at micro- and meso-scale, is performed. Constitutive relationships describing influence of temperature and material damage upon its intrinsic permeability at high temperature for 4 types of HPC are deduced. In the Part II of this paper (Gawin, et al. 2005) effect of two different damage-permeability coupling formulations on the results of computer simulations concerning hygro-thermo-mechanical performance of concrete wall during standard fire, is numerically analysed.

• Applied Microscopy
• /
• v.47 no.3
• /
• pp.160-164
• /
• 2017

Electron crystallography has been used as the one of powerful tool for studying the structure of biological macromolecules at high resolution which is sufficient to provide details of intramolecular and intermolecular interactions at near-atomic level. Previously it commonly uses two-dimensional crystals that are periodic arrangement of biological molecules, however recent studies reported a novel technical approach to electron crystallography of three-dimensional crystals, called micro electron-diffraction (MicroED) which involves placing the irregular and small sized protein crystals in a transmission electron microscope to determine the atomic structure. In here, we review the advances in electron crystallography techniques with several recent studies. Furthermore, we discuss the future direction of this structural approach.