• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1733-1736
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• 2005

Many studies have been carried out to produce 3D features in the size range between $10{\mu}m\~10,000{\mu}m$, called Meso-scale. If these miniaturized systems have high relative accuracy and good volumetric utilization, it is possible to manufacture more complex and accurate shapes with various materials as well as there are advantages of reducing energy, space and resources. Due to imperfect components and misalignment in assembly, it is necessary to assess the accuracy of the miniaturized system itself to obtain high relative accuracy. Laser interferometers are widely used to measure geometric errors called as quasi-static errors. For miniaturized system, however, it is difficult to install the required accessories such as optics and the measuring range is limited because of the size of the system and also this method is very expensive. Moreover, it is impossible to measure each error component simultaneously. A new system to measure simultaneously multiple geometric errors is proposed using capacitance sensors. Each error was measured using capacitance sensors and a measurement algorithm was mathematically derived. The experiments show that the proposed measurement system can be used effectively to assess the accuracy of miniaturized system at a low cost.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.133-138
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• 2016

Force control and collision detection for a robot are usually conducted using a 6-axis force/torque sensor mounted at the end-effector. However, this scheme suffers from high-cost and the inability to detect collisions at the robot body. As an alternative, joint torque sensors embedded in each joint were used, which also suffered from various errors in torque measurement. To resolve this problem, a robot joint module with an improved joint torque sensor is proposed in this study. In the proposed torque sensor, a cross-roller bearing and disk-type coupling are added to prevent the moment load from adversely affecting the measurement of the joint torque under consideration. This joint design also aims to reduce the stress induced during the assembly process of the sensor. The performance of the proposed joint torque sensor was verified through various experiments.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.4
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• pp.213-219
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• 2007

Glass-to-metal contact should be prevented in the design of any structural glass component. Because glass is extremely brittle and will fracture readily if even a small point load is applied. If the assembly includes a glass component supported by metallic structure, designers should provide a pliable interface of some kind between the two parts. But there happens high demand of glass-to metal contact in semiconductor industries due to adoption of dry cleaning process as one of the good solution to reduce running cost - carry out equipments cleaning with high corrosive and etching gas such as CF4 with keeping process temperature as the same as high service temperature. Therefore the quartz glass have to be received compression by direct contact with metal as the form of weight itself and vacuum pressure and fatigue by vibrations caused by process during the process. In this paper investigation will be carried out on fracture behavior of quartz glass contacted with metal directly under local load and fatigue given by process vibration with apparatus which can give $lox{\backslash}cal$ load and vibration through PZT ceramics to give guideline to prevent unintended fracture of quartz glass.

• Smart Structures and Systems
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• v.8 no.1
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• pp.139-155
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• 2011

Polymeric thin-film assemblies whose bulk electrical conductivity and mechanical performance have been enhanced by single-walled carbon nanotubes are proposed for measuring strain and corrosion activity in metallic structural systems. Similar to the dermatological system found in animals, the proposed self-sensing thin-film assembly supports spatial strain and pH sensing via localized changes in electrical conductivity. Specifically, electrical impedance tomography (EIT) is used to create detailed mappings of film conductivity over its complete surface area using electrical measurements taken at the film boundary. While EIT is a powerful means of mapping the sensing skin's spatial response, it requires a data acquisition system capable of taking electrical impedance measurements on a large number of electrodes. A low-cost wireless impedance analyzer is proposed to fully automate EIT data acquisition. The key attribute of the device is a flexible sinusoidal waveform generator capable of generating regulated current signals with frequencies from near-DC to 20 MHz. Furthermore, a multiplexed sensing interface offers 32 addressable channels from which voltage measurements can be made. A wireless interface is included to eliminate the cumbersome wiring often required for data acquisition in a structure. The functionality of the wireless impedance analyzer is illustrated on an experimental setup with the system used for automated acquisition of electrical impedance measurements taken on the boundary of a bio-inspired sensing skin recently proposed for structural health monitoring.

• Smart Structures and Systems
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• v.3 no.2
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• pp.189-200
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• 2007

As a functional material, shape memory alloy (SMA) has attracted much attention and research effort to explore its unique properties and its applications in the past few decades. Some of its properties, in particular the electrical resistance (ER) based self-sensing property of SMA, have not been fully studied. Electrical resistance of an SMA wire varies during its phase transformation. This variation is an inherent property of the SMA wire, although it is highly nonlinear with hysteresis. The relationship between the displacement and the electrical resistance of an SMA wire is deterministic and repeatable to some degree, therefore enabling the self-sensing ability of the SMA. The potential of this self-sensing ability has not received sufficient exploration so far, and even the previous studies in literature lack generality. This paper concerns the utilization of the self-sensing property of a spring-biased Nickel-Titanium (Nitinol) SMA actuator for two applications: ER feedback position control of an SMA actuator without a position sensor, and estimation of the opening of a SMA actuated valve. The use of the self-sensing property eliminates the need for a position sensor, therefore reducing the cost and size of an SMA actuator assembly. Two experimental apparatuses are fabricated to facilitate the two proposed applications, respectively. Based on open-loop testing results, the curve fitting technique is used to represent the nonlinear relationships between the displacement and the electrical resistance of the two SMA wire actuators. Using the mathematical models of the two SMA actuators, respectively, a proportional plus derivative controller is designed for control of the SMA wire actuator using only electrical resistance feedback. Consequently, the opening of the SMA actuated valve can be estimated without using an extra sensor.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.469-480
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• 2013

This study suggests 12 products regarding the pending question of tourism package price mechanism which is linked directly and indirectly to Jeju Tourism, and shows the following conclusions through inspection in mental accounting principles and framing effect based on prospect theory. First, when presenting the price list of the tourism package, it is needed to present in price bundling. Second, it is proven that it is desirable that information about discount prices open the individual discount information of the basic package and option package to public. Third, it is discovered that experienced tourists in purchasing tourism products are more sensitive to price information (price discount) than inexperienced tourists, so that framing effect conform to Knowledge-assembly theory. The current questions of this study are that 'no discount' information should be presented in bundling, that the method of framing is important in presenting discount product information. It is required not only to grasp the viewpoint of modern people in purchasing tourism products, but also to present ready-to-serve products which can save time, effort, cost to give stability in mental accounting principles.

• Journal of Biomedical Engineering Research
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• v.34 no.3
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• pp.111-116
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• 2013

Finite element analysis(FEA) has been extensively applied in the analyses of biomechanical properties of stents. Geometrically, a closed-cell stent is an assembly of a number of repeated unit cells and exhibits periodicity in both longitudinal and circumferential directions. This study concentrates on various parameters of the FEA models for the analysis of drug-eluting biodegradable polymeric stents for application to the treatment of coronary artery disease. In order to determine the mechanical characteristics of biodegradable polymeric stents, FEA was used to model two different types of stents: tubular stents(TS) and helicoidal stents(HS). For this modeling, epigallocatechin-3-O-gallate (EGCG)-eluting poly[(L-lactide-co-${\varepsilon}$-caprolactone), PLCL] (E-PLCL) was chosen as drug-eluting stent materials. E-PLCL was prepared by blending PLCL with 5% EGCG as previously described. In addition, the effects of EGCG blending on the mechanical properties of PLCL were investigated for both types of stent models. EGCG did not affect tensile strength at break, but significantly increased elastic modulus of PLCL. It is suggested that FEA is a cost-effective method to improve the design of drug-eluting biodegradable polymeric stents.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.93-101
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• 2006

Recently, work-related musculoskeletal disorders (WMSDs) become a hot issue in the industrial fields. To prevent the potential risk of workers, various approaches have been adopted. One of the approaches is to improve the design of product, that of jig (or fixture) and that of workstation in the early stage of the development. 3D simulation technology is known as the powerful method for detecting such problems before constructing the workstation, because it is possible to evaluate the posture of worker using 3D models in a cyber space. It enables to find the unexpected problems and save the time and cost for redesign and rework. This paper introduces a 3D simulation case study of workers in an excavator factory. 3D models of products, jigs were developed with CATIA. The assembly processes were animated in IGRIP and DPM. Finally the various postures of worker were simulated using Human. As a result, some postures were analysed as the risky jobs and the result of simulation was used to improve the system.

• Korean Journal of Veterinary Service
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• v.39 no.1
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• pp.41-49
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• 2016

In the present study, fast and robust methods for the next generation sequencing (NGS) were developed for analysis of PRRSV full genome sequences, which is a positive sensed RNA virus with a high degree of genetic variability among isolates. Two strains of PRRSVs (VR2332 and VR2332-R) which have been maintained in our laboratory were used to validate our methods and to compare with the sequence registered in GenBank (GenBank accession no. EF536003). The results suggested that both of strains had 100% coverage with the reference; the VR2332 had the coverage depth from minimum 3 to maximum 23,012, for the VR2332-R from minimum 3 to maximum 41,348, and 22,712 as an average depth. Genomic data produced from the massive sequencing capacities of the NGS have enabled the study of PRRSV at an unprecedented rate and details. Unlike conventional sequence methods which require the knowledge of conserved regions, the NGS allows de novo assembly of the full viral genomes. Therefore, our results suggested that these methods using the NGS massively facilitate the generation of more full genome PRRSV sequences locally as well as nationally in regard of saving time and cost.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.207-214
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• 2020

This study analyzes the method for easily constructing a simple space in various environments. It also analyzes cases of modular prefab construction structures and explores various solutions and development directions that can form temporary residential spaces. This research intends to propose the diverse methods and solutions for constructing residential space for users' stable living environment in various unpredictable situations. This study amis to collect and analyze cases of various foreign patents related to the subject. With the analysis on the patents case, the prefab structures are mainly grouped into 4 types of 1) Assembly method using small parts, 2) Prefab module stacking method, 3) Space expansion method, and 4) Production methods of detailed elements. Based on the results, future research will inquire the lower cost and more efficient way of constructing prefab structure.