• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.3 no.2
• /
• pp.126-130
• /
• 2002

This paper presents the basic concept of new solid freeform fabrication system using rapid prototyping method. The system could fabricate an arbitrary ceramic form by laser cutting, transferring, stacking, and sintering of each slide. The system consists mainly of laser apparatus. X-Y table, a slide transferring system, and electric oven. The system could fabricate an object that has smooth surface with comparatively short period of time. The system is effective in terms of its direct fabrication capability without second mechanical process. The fabricated shape could directly be used as part of a whole assembly and therefore its method could be applied to various application areas.

• Journal of Convergence for Information Technology
• /
• v.11 no.6
• /
• pp.219-225
• /
• 2021

As for the battery package method, a prismatic package method is preferred for stability reasons, but it is rapidly expanding due to the stability verification of a pouch type package. The pouch type using the lamination process has an advantage of high battery energy density because it can reduce space waste, but has a disadvantage of low productivity. Therefore, in this paper, by extracting edge detection algorithm precision, pattern algorithm precision, and motion controller recall rate by improving backlight lighting fixtures to minimize light diffusion, securing standards for stereo camera position relationship displacement monitoring, and securing standards for lens release monitoring. We propose to implement a system that ensures accuracy and reliability in positioning. As a result of the experiment, the proposed system shows an average error range of 0.032mm for edge detection, 0.02mm for pattern algorithm, and 0.014mm for motion controller, thus ensuring the accuracy and reliability of the positioning mechanism.

• Korean Chemical Engineering Research
• /
• v.57 no.5
• /
• pp.706-713
• /
• 2019

In this study, basic research was conducted to provide guidelines for selecting printers and materials suitable for each application case by analyzing 3D printing method and surface characteristics of materials suitable for microfluidic system. We have studied the surface characteristics according to the materials for the two typical printing methods: The most commonly used method of Fused Deposition Modeling (FDM) printing and the relatively high resolution method of Stereolithography (SLA) printing. The FDM prints exhibited hydrophilic properties before post - treatment, regardless of the material, but showed hydrophobic properties after post - treatment with acetone vapor. It was confirmed by the observation of surface roughness using SEM that the change of the contact angle was due to the removal of the surface structure by post-treatment. SLA prints exhibited hydrophilic properties compared to FDM prints, but they were experimentally confirmed to be capable of surface modification using hydrophobic coatings. It was confirmed that it is impossible to make a transparent specimen in the FDM method. However, sufficient transparency is secured in the case of the SLA method. It is also confirmed that the electroporation chip of the digital electroporation system based on the droplet contact charging phenomenon was fabricated by the SLA method and the direct application to the microfluidic system by demonstrating the electroporation successfully.

• Economic and Environmental Geology
• /
• v.34 no.2
• /
• pp.217-226
• /
• 2001

Stable isotope, paleoceanographic and sedimentological analyses were carried out along the core Ml5612 from the Mid-Atlantic Ridge. Distinct negative ${\delta}^{18}O anomalies punctuate the planktonic isotope records and correlate with the Heinrich-IRD cvents. The IRD layer in the corc contains varying amounts of quartz, K-feldspar, plagioclase, calcite, dolomite and mica, in which detrital carbonate contributes between I and 13% (except H3 and H6). Anomalies are strongest in the N. pachydenna (sin.) isotope record. Systematic changes in the ${\delta}^{18}O offset of G. hul/aides and G. inJlata signify variations in mid-latitude thermocline structure. In conjunction with negative benthic ${\delta}^{13}C anomalies, the data document a stronger contribution of a ${\delta}^{13}C depleted, nutrient-rich water mass during the IRD events. The ${\delta}^{13}C amplitude of > 1 $\textperthousand$ between 25 and 57 ka indicates changes between northern source (NADW) and southern source (AABW) water masses at this site. The IRD layers in the core Ml56l2 are correlative with those from the core S075-26KL and DSDP 609. The IRD layers from the Portuguese margin arc coeval with HI, H2 and H4 of the open North Atlantic. This similarity (and/or synchronicity in both regions may have been resulted from common changes in a North Atlantic thermohaline switch.

• Composites Research
• /
• v.13 no.1
• /
• pp.40-49
• /
• 2000

The objective of this research is to develop the impact monitoring techniques providing impact identification and damage diagnostics of smart composite laminates susceptible to impacts. This can be implemented simultaneously by using the acoustic waves by the impact loads and the acoustic emission waves from damage. In the previous research, we have discussed the impact location detection process in which impact generated acoustic waves are detected by PZT using the improved neural network paradigm. This paper describes the implementation of time-frequency analysis such as the Short-Time Fourier Transform (STFT) and the Wavelet Transform (WT) on the determination of the occurrence and the estimation of damage.

• Composites Research
• /
• v.15 no.5
• /
• pp.19-26
• /
• 2002

Real defects in composite structures were detected by using laser measuring system. Four types of real defects, that is, impact-induced delamination in a composite laminate, debond in a honeycomb structure, free-edge delamination in a composite laminate and debond in an adhesive joint, were made by applying several types of loads to the specimens. Laser measuring system such as ESPI and shearography technique were used to detect those defects. Thermal loading method, which can easily induce the surface deformation of specimen, was used to detect the defects. Experimental results show that the defects in composite structures could be easily detected by ESPI and shearography technique. Moreover, it shows that ESPI and shearography technique could be usefully applied to the detection of defects in various kinds of composite structures.

• Journal of Korean Association for Spatial Structures
• /
• v.6 no.3 s.21
• /
• pp.93-101
• /
• 2006

Recently the floor vibration of apartment is often beginning to make its appearance of the environmental dispute, the standard floor system of housing are suggested for the settlement of this issue by government. For the slab vibration analysis on the laminated floor system of apartment, it is required the effectively analytical method of the floor system considering laminated theory. In this paper, more effective modeling methods of laminated floor slab are proposed for the method of accurate rigidity evaluation. By using the advanced modeling method, the more accurate vibration response can be obtained and can accurately evaluate the rigidity of living room floor system of apartment with different laminated materials.

• Land and Housing Review
• /
• v.4 no.2
• /
• pp.185-192
• /
• 2013

This study presents application effects of hybrid seismic isolation system to realize high seismic performance for low-rise lightweight buildings through a non-linear analysis and onsite experiments. The complex seismic isolation system applied in this study is a method of mixing sliding bearing and laminated rubber bearing in order to overcome limitation of laminated rubber bearing in increasing natural period of the whole seismic isolation system. As a result of the non-linear analysis, seismic isolation buildings designed with complex seismic isolation system are safe because its maximum response displacement is within allowable design displacement even for a strong earthquake which rarely occurs and its maximum response shear is less than design seismic force. As a result of the onsite experiment, the rigidity of seismic isolation stories corresponds to approximately 95.8% of the design equivalent stiffness value. This indicates that actual properties of the whole seismic isolation system correspond to design values.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.11
• /
• pp.1273-1281
• /
• 2014

Tissue engineering is an emerging research field that has the potential to restore, regenerate and repair damaged bone tissue and organs. Tricalcium phosphate and hydroxyapatite biomaterials-based calcium phosphate are excellent materials that have both osteoconduction and biocompatibility for bone tissue regeneration. In this study, solution structures were successfully fabricated using a fused deposition modeling system based on deposition and heating devices. The morphology characteristics of the bioceramic scaffolds sintered at a temperature of $1,300^{\circ}C$ were analyzed by scanning electron microscopy. The effects of various blended TCP/HA ratio on the microstructure and shrinkage were studied. The mechanical properties of the scaffolds were measured using a compression testing machine from stress-strain curves on the crosshead velocity of 1 mm/min. The fabricated scaffolds were evaluated by cell proliferation tests of MG-63 cells. The results of this study suggest that the blended TCP(75 wt%)/HA(25 wt%) scaffold is an appropriate scaffold for bone tissue regeneration.

• Composites Research
• /
• v.17 no.4
• /
• pp.53-60
• /
• 2004

This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP laminate plates based on considerations of stress wave propagation theory. The absorbed energy of T300 orthotropic composites is higher than that of quasi-isotropic specimen over impact energy 6.8J, but in case of using T700 fiber, much difference does not show. Also, absorbed energy of T300 orthotropic composites, which are composed of the same stacking number and orientation became more than that of T700 fiber specimen; however there was no big difference in case of quasi-isotropic specimens. The delamination areas of the impacted specimen were measured with the ultrasonic C-scanner to find correlation between impact energy and delamination area. The fracture surfaces were observed by using the SEM (scanning electron microscope) through a low-velocity impact test in order to confirm the fracture mechanism.