• Design & Manufacturing
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• v.14 no.3
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• pp.31-36
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• 2020

In injection molding processes, the property of molten resin should be characterized accurately. Among several properties, the PvT state is the most important one, since it affects the shrinkage, warpage, molded weight, and the part density. Thus, the PvT data is crucial to the simulation of the injection molding process. This work shows how such a measurement can be performed for a semi-crystalline and amorphous polymers. The PvT measurement has been conducted using a capillary rheometer using a suitable accessory that blocks the capillary. The results have shown that the PvT data can be obtained using such a rheometer and then the PvT coefficients of the Tait equation can be reached.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.05a
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• pp.384-387
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• 2004

The purpose of the present investigation was to develop a novel method for cell immobilization. Aureobasidium pullulans cells were mixed with an alginate solution, and the mixture was extruded to form small gel beads as hydrated- immobilized cells. The beads were then placed at $-15^{\circ}C$ for 6-24 h to induce freeze-dehydration. The freeze-dehydration resulted in shrinkage of beads due to water removal reducing bead volume by 82% and bead weight by 85%. The dehydrated beads were successfully used for the production of fructo-oligosaccharides in a model reactor system. This study showed that bioreactor performance can be improved up to 2 times by the use of the dehydrated beads.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.606-611
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• 1999

Recently , the hydraulic fill method is commonly used in many reclamation projects due to lack of fill materialss. The method of hydraulic fill i recalmation is executed by transporting the mixture of water -soil particles into a relcaimed land through dredging pipes, then the dredged soil particels settle down in thewater orflow over an out flow weir with the water. The amount of the volume reductions of dredged soil is considered the sum of the overall settlement by descication shrinkage and self-weigth consolidation and the loss of soil particles flow over a weir. In the present study, hydrometer analysis was performed with the soil samples obtained bofore and after dredging to estimate the amount of soil particles residual at reclaimed area and the loss of soil particles , then it was suggested the method of determining the loss ratio of dredged soils from the tests results. The hydrometer analysis of in-situ soil samples showed that the loss ratio of dredged soils is lowest at the nearest point to dredge pipe and highest at the nearest point of out flow weir.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.369-372
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• 2005

This study is about physical properties of concrete with changing displacement ratio of calcium sulfa aluminates(CSA) type admixture. Firstly, test shows that as displacement ratio of CSA increases and setting properties changes, fluidity and air contents decreases. In water to binder ratio 35$\%$ and 45$\%$, concrete using the cement replacing CSA 4$\%$ by volume shows that bleeding decreases 94.7$\%$ and 74.3$\%$ respectively, compared with plain concrete. In addition, setting time was promoted around 3 to 6 hour and 1 to 4 hour respectively. For harden concrete, increase of displacement ratio caused tendency of higher compressive strength as OPC has at early age. Replacing higher CSA admixture led to reduce of drying shrinkage.

• Journal of the Korean Ceramic Society
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• v.34 no.7
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• pp.713-721
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• 1997

Molecular dynamic (MD) simulations with new interatomic potential function including the covalent bond were performed on the phase transition of $\alpha$-quartz-type GeO2 under high pressure. The optimized crystal structure and the pressure dependence of the lattice constant showed higher reproducibility than the previous models and were in very good agreement with the experimental data. A phase transition of $\alpha$-quartz and $\alpha$-quartz-type GeO2 by simulation was found approximately 24 GPa and 6-7 GPa, respectively. This phase transition involved an abrupt volume shrinkage and showed 4-6 coordination mixed structure with the increasing in the coordination number of cation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.153-156
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• 2009

This study investigated the fundamental properties corresponding to various length changes on NY fiber reinforced concrete. For results of fresh concrete, the slump and air content were declined, but the unit volume weight and vebe time were increased. For the hardened concrete properties, the compressive strength showed increasing tendency according to the NY fiber length. The dry and autogenous shrinkage also decreased compared with Plain. Generally, the caes that 19 mm NY fiber was used was better than any other cases.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.3
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• pp.75-80
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• 2001

Holographic polymer dispersed liquid crystals (HPDLCs) have fabricated by irradiating an Ar-ion laser ( ${\lambda}$=514nm) at various intensity on LC/acrylate monomer mixtures which were sandwitched between two ITO coated glass plates. Monomer systems were composed of dipentaerythritol-hydroxy penta acrylate (DPHPA, f=5)/monofunctional acrylate monofunctional monomers. The LC used in this system was E7 (BL001, Merck). Gratings were fabricated by periodic interference of twobeams. Reflection efficiency-irradiation intensity-monomer type relationships were obtained from the UV-visible spectra of the HPDLC films. Peaks were found at a bit smaller wavelength than 514nm, due to the shrinkage of mixture volume upon polymerization. Real time measurements of diffraction efficiency have been obtained according to monomer types and LC contents.

• The Journal of Korea Robotics Society
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• v.16 no.1
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• pp.29-34
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• 2021

Traditional actuation system such as electric and pneumatic actuator has obvious advantages and disadvantages. To combine advantages and compensate disadvantages of the traditional actuation, a pneumatic actuation system with an internal air pressure source is noteworthy approach. In this paper, a soft pneumatic actuation system based on origami pump is described for haptic feedback glove. To improve wearability, an origami pump is introduced because the origami pump is much lighter than air compressor. The miniaturized electric actuation system is also designed with 3D printed planetary gear in order to reduce the volume of the system. To figure out the performance of the system, shrinkage distance of origami pump was measured with vision camera. The pressure in the origami pump was also estimated to understand the performance of the system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.193-194
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• 2020

Recently, as the use of high-performance concrete has become common, various problems related to high-performance concrete have become an issue. Among them, self-shrinkage of cement paste due to low water cement ratio is known to cause problems in the volume stability of concrete. To improve this, studies related to the mixing technology of cement-based materials and nano materials have been actively conducted. Looking at the results of prior research related to nano material mixing technology, generally, research results have been reported in which nano materials are incorporated into cement-based materials to improve material properties1). Among them, it was shown that the mechanical performance and various types of functionality of the cement composite are expressed. Among nano materials, carbon nanotubes (hereinafter referred to as CNTs) and graphenes are used in a mixture with cement-based materials. Accordingly, this study intends to compare the mechanical properties by incorporating various CNTs and graphene into cement paste.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.70-71
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• 2021

The unit quantity that affects the workability, shrinkage cracking, and durability of concrete is an important factor. Methods for measuring the unit quantity include a high frequency heating method, a capacitance method, a unit volume mass method, and a simple method. However, these methods have the disadvantage of poor measurement method, time required, and precision. To solve this problem, a relatively simple and fast measurement method was adopted to compensate for the shortcomings through a Frequency Domain Reflection (FDR) sensor, and the unit quantity was used. In addition, the measurement data was analyzed by deep learning to evaluate the unit quantity of concrete.