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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
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Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 29, Issue 12 - Dec 2012
Volume 29, Issue 11 - Nov 2012
Volume 29, Issue 10 - Oct 2012
Volume 29, Issue 9 - Sep 2012
Volume 29, Issue 8 - Aug 2012
Volume 29, Issue 7 - Jul 2012
Volume 29, Issue 6 - Jun 2012
Volume 29, Issue 5 - May 2012
Volume 29, Issue 4 - Apr 2012
Volume 29, Issue 3 - Mar 2012
Volume 29, Issue 2 - Feb 2012
Volume 29, Issue 1 - Jan 2012
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A Non-contact Two-Dimensional Position Sensing Device Using Electromagnetic Induction
Ryu, Young-Kee ; Koh, Kuk-Won ; Kim, Hak-Soo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1159~1163
DOI : 10.7736/KSPE.2012.29.11.1159
In this paper, we would like to introduce two dimensional non-contact position sensor by using an electromagnetic induction based coil system and an algorithm to estimate the position of pointer. The sensor which will introduce in this paper is composed of a pointer including LC resonant circuit and a sensor board to detect the electromagnetic signal from the pointer. Because of the simplicity shape of the line antenna, low cost and free form curved shape of the sensor device is possible. In this research, we proposed a new two dimensional non-contact type electromagnetic sensor system and realized the proposed sensor device. From the experiments, the proposed device can be employed for the two dimensional position sensor.
Integrated IR Photo Sensor for Display Application
Jeon, Ho-Sik ; Heo, Yang-Wook ; Lee, Jae-Pyo ; Han, Sang-Youn ; Bae, Byung-Seong ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1164~1169
DOI : 10.7736/KSPE.2012.29.11.1164
This paper presents a study of an integrated infrared (IR) photo sensor for display application. We fabricated hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) and hydrogenated amorphous silicon germanium thin film transistor (a-SiGe:H TFT) which were bottom gate structure. We investigated the dependence of a-SiGe:H TFT characteristics on incident wavelengths. We proposed photo sensor which responded to wavelengths of IR region. Proposed pixel circuit of photo sensor was consists of switch TFT and photo TFT, and one capacitor. We developed integrated photo sensor circuit and investigated the performance of the proposed sensor circuit according to the input wavelengths. The developed photo sensor circuit with a-SiGe:H TFT was suitable for IR.
LED Output Light Characteristic by Lens Eccentricity
Kim, Young-Chul ; Lyu, Jong-Sun ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1170~1173
DOI : 10.7736/KSPE.2012.29.11.1170
We have investigated the LED lens eccentricity effect on light intensity distribution. For the purpose, we introduced an equation of focal length for paraboloid, and then made a comparative analysis of the theoretical result and 3-D simulation result.
Compensation of Resistance Variation due to Temperature in Voltage Measurement System
Min, Sang-Jun ; Kim, Jin-Sung ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1174~1177
DOI : 10.7736/KSPE.2012.29.11.1174
In voltage measurement by using voltage divider with series resistors, error is generated caused by the variation of resistance. In order to reduce these errors, the hardware cost tends to increase in the previous works. In the proposed method, three resistors are used for the voltage divider of which the organization is adjusted by using switches. Three voltages are measured and the ratio of resistance is calculated based on the measured voltages. Since the resistance ratio is calculated by measuring voltages and additional hardware cost is minimal, the voltage can be measured with high accuracy and low cost. Experimental results show that the mean absolute error is 12.1 mV when the input voltage ranges from 5 V to 50 V.
Evaluation of the Organic Linings at Gas Desulfurization System
Song, Yo-Seung ; Kwan, Hyun-Ok ; Jho, Nam-In ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1178~1182
DOI : 10.7736/KSPE.2012.29.11.1178
The organic linings at flue gas desulfurization systems (FGD system) in power plant have the excellent chemical properties but, lose the anticorrosive properties according to the aging with environment conditions. The properties of the organic linings depend on the manufacturing company. Therefore, the basic properties of organic linings for the preestimate of life time should be examined by conducting the aging and the bond strength test according to temperature. The pre-aging samples were compared with the post-aging samples. The temperature conditions of the aging process were 70, 150 and
. The bond strength was calculated and the cross sections of fracture surface were examined by optical microscope and SEM. The
was examined by DSC, DTA and TGA.
Influence of Electrode and Thickness of Organic Layer to the Emission Spectra in Microcavity Organic Light Emitting Diodes
Kim, Chang-Kyo ; Han, Ga-Ram ; Kim, Il-Yeong ; Hong, Chin-Soo ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1183~1189
DOI : 10.7736/KSPE.2012.29.11.1183
Organic light-emitting diodes (OLEDs) using microcavity effect have attracted great attention because they can reduce the width of emission spectra from organic materials, and enhance brightness from the same material. We demonstrate the simulation results of the radiation properties from top-emitting organic light-emitting diodes (TE-OLEDs) with microcavity structures based on the general electromagnetic theory. Organic materials such as N,N'-di (naphthalene-1-yl)-N,N'-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (
) as emitting and electron transporting layer are used to form the OLEDs. The organic materials were sandwiched between anode such as Ni or Au and cathode such as Al, Ag, or Al:Ag. The devices were characterized with electroluminescence phenomenon. We confirmed that the simulation results are consistent with experimental results.
FE-Analysis of Hot Forming of Al Large Thick Plate for Spherical LNG Tank Considering Cooling Performance of Grid-Typed Die
Lee, Jung-Min ; Lee, In-Kyu ; Kim, Dae-Soon ; Kwon, Il-Keun ; Lee, Seon-Bong ; Kim, Byung-Min ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1190~1198
DOI : 10.7736/KSPE.2012.29.11.1190
A hot forming of large thick Al plate using a grid-type hybrid die is a process to make a shell plate for the production of a spherical LNG tank. This process is characterized by using a grid-typed die with an additional air cooling system for reducing the cooling time of the heated plate after hot forming. The process consists of the plate's feeding, heating, forming and cooling in detail and each of them is continuously performed along the rail. This paper was designed to propose the analytical and experimental methods for determining the convection and interfacial heat transfer coefficients required in hot forming analysis of Al plate. These values in the analysis are to reproduce numerically the cooling performance of grid-typed die and cooling device. Interfacial heat transfer was obtained from the heat transfer experiments for different pressures and inverse analysis method. To verify the efficiency of the coefficient values obtained from above methods, FE analysis and experiment of the hot spherical-forming process were conducted for a small-scaled model. The convection coefficient was also calculated from flow analysis of air released by cooling device within grid-typed die using ANSYS-CFX.
A Study on Particular Abnormal Gait Using Accelerometer and Gyro Sensor
Heo, Geun-Sub ; Yang, Seung-Han ; Lee, Sang-Ryong ; Lee, Jong-Gyu ; Lee, Choon-Young ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1199~1206
DOI : 10.7736/KSPE.2012.29.11.1199
Recently, technologies to help the elderly or disabled people who have difficulty in walking are being developed. In order to develop these technologies, it is necessary to construct a system that gathers the gait data of people and analysis of these data is also important. In this research, we constructed the development of sensor system which consists of pressure sensor, three-axis accelerometer and two-axis gyro sensor. We used k-means clustering algorithm to classify the data for characterization, and then calculated the symmetry index with histogram which was produced from each cluster. We collected gait data from sensors attached on two subjects. The experiment was conducted for two kinds of gait status. One is walking with normal gait; the other is walking with abnormal gait (abnormal gait means that the subject walks by dragging the right leg intentionally). With the result from the analysis of acceleration component, we were able to confirm that the analysis technique of this data could be used to determine gait symmetry. In addition, by adding gyro components in the analysis, we could find that the symmetry index was appropriate to express symmetry better.
Control Gain Tuning of the 3-DOF Micro Parallel Mechanism Platform Via Design of Experiment Methodology
Seo, Tae-Won ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1207~1213
DOI : 10.7736/KSPE.2012.29.11.1207
Typically commercial controllers do not give data of the controller gains. Therefore, it is very hard to determine the optimal controller gain even though the dynamic model is derived. In this case, design of experiment (DOE) methodology can be a powerful tool for gain tuning. In this research, gain tuning process is proposed based on the DOE. Micro parallel mechanism platform with 3 degrees-of-freedom (DOF) is used for the experiments. Controller gains are measured indirectly from the voltages of adjustable resistors. The controller gains of three actuators are optimized by two or three steps, respectively. The correlations of the controller gains are also analyzed. The process and methodology can be adopted in gain tuning of other mechanical systems.
Vibrational Characteristics of Magnetostrictive Materials for a Vibration Assisted Cutting Device
Lee, Ho-Cheol ; Kim, Gi-Dae ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1214~1220
DOI : 10.7736/KSPE.2012.29.11.1214
Vibration assisted cutting (VAC) is one of the promising methods for precision machining, which has been normally equipped with piezoelectric materials. In this paper, a feasibility of applying magnetostrictive materials to VAC as a cutting device instead of piezoelectric materials was studied. For this, the vibrational characteristics of a magnetostrictive material was investigated with respect to a coil design, a preload, and the effects of a biasing and an exciting magnetic fields. The output strain of a magnetostrictive material is restricted due to an increasing inductive impedance as the exciting frequency increases and the heat of coil, etc. Through the experimental results, it was found that the biasing and the exciting magnetic field affected the output performance significantly but not the preload. In conclusion, the magnetostrictive material could be used only in the low frequency range but not a good candidate for high frequency actuating application.
Development of a Miniaturized Microforming System and Investigation of Deformation Behavior of Material for the Production of Micro Components by Forming
Nam, Jung-Soo ; Park, Il-Gu ; Lee, Sang-Won ; Kim, Hong-Seok ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1221~1227
DOI : 10.7736/KSPE.2012.29.11.1221
As demands on micro-products increase significantly with raising functional integration and increasing complexity, microfoming attracts a lot of attention in the manufacture of micro-products. Since the conventional big forming systems are not adequate to achieve sufficient tolerances of micro-scale parts, it is necessary to reduce the scale of the forming equipment and devices. In addition, understandings on the size effects, which exist in the material behavior and process characterization of microforming processes, need to be expanded. In this study, a miniaturized forming system based on the ball screw and servo motor actuator was developed for the efficient micro-parts production. In addition, tensile tests and cylindrical upsetting experiments were performed to evaluate the performance of the microforming system and to investigate the flow stress and friction size effects in microforming processes.
Effective Analysis on the Mechanical Behavior of a Refrigerator using Equivalent Material Properties of Multi-layers
Park, Jeong-Hyun ; Lee, Dong-Kyu ; Park, Sang-Hu ; Park, Ki-Hong ; Ha, Byeong-Kuk ; Kim, Hyeong-Sik ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1228~1235
DOI : 10.7736/KSPE.2012.29.11.1228
A refrigerator has many components which are made from diverse materials such as metal, polymer, plastic, and rubber. So, it generally requires much time and efforts to build up an analysis model in finite element analysis. In this work, to reduce the computational time and efforts a simplified modeling method was proposed for the analysis of a refrigerator. Occasionally, a stick-slip noise occurs in a refrigerator due to relative slip between shelf and inner-case. When we solve the problem by a FE analysis, we should model the structures with detail for considering the contact conditions; by this reason, too many efforts are consumed in the conventional analysis method. Through this work, we shows the concept of simplifying approach and a good agreement with the results of a real model analysis. And also, the evaluation of the proposed method and the application of contact analysis using the simplified model are discussed.
Study on Application of Equivalent Stiffness Modeling Method for Static Aeroelastic Analysis of Large Scale Wind Turbine Rotor System
Cha, Jin-Hyun ; Ku, Tae-Wan ; Kim, Jeong ; Kang, Beom-Soo ; Song, Woo-Jin ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1236~1244
DOI : 10.7736/KSPE.2012.29.11.1236
A equivalent stiffness modeling has been performed for extracting the equivalent stiffness properties which are orthotropic elastic model from a large scale wind turbine rotor blade so that structure model can be constructed more simply for the three dimensional static aeroelastic analysis. In order to present the procedure of equivalent stiffness modeling, NREL 5MW class wind turbine rotor having the three stiffness information which are flapewise, edgewise and torsional stiffness was chosen. This method is based on applying unit moment at the tip of the blade as well as fixing all degree of freedom at the blade root and calculating the displacement from the load analysis to obtain the elastic modulus corresponding to equivalent stiffness referred to the NREL reports on blade divided into 5 sections respectively. In addition, one section was divided into 3 parts and the trend functions were used to make the equivalent stiffness model more correctly and quickly. Through the comparison of stiffness between the reference values and calculated values from equivalent stiffness model, the investigation of the accuracy on the stiffness values and the efficiency for constructing the model was conducted.
Analysis of Effective Anisotropic Elastic Constants and Low-Velocity Impact of Biomimetic Multilayer Structures
Lee, Jong-Won ; Beom, Hyeon-Gyu ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1245~1255
DOI : 10.7736/KSPE.2012.29.11.1245
Effective elastic constants of biomimetic multilayer structures with hierarchical structures are evaluated based on the potential energy balance method. The effective anisotropic elastic constants are used in analyzing low-velocity impact of biomimetic multilayer structures consisting of mineral and protein. It is shown that displacements of biomimetic multilayer structures strongly depend on the volume fraction of mineral and hierarchical level. The effect of the volume fraction of mineral and hierarchical level on the contact force and stresses at the impact point are also discussed.
Replication Characteristics of Micro-Patterns according to the Vibration Transmission Direction in the Ultrasonic Imprinting Process
Seo, Young-Soo ; Lee, Ki-Yeon ; Cho, Young-Hak ; Park, Keun ;
Journal of the Korean Society for Precision Engineering, volume 29, issue 11, 2012, Pages 1256~1263
DOI : 10.7736/KSPE.2012.29.11.1256
The present study covers the ultrasonic patterning process to replicate micro-patterns on a polymer substrate. The ultrasonic patterning process uses ultrasonic waves to generate frictional heat between an ultrasonic horn and the polymer substrate, from which the surface region of the polymer substrate is softened sufficiently for the replication of micro-patterns. The ultrasonic patterning process can divided into two categories according to the direction of vibration transmission: direct patterning and indirect patterning. The direct patterning uses a patterned horn, and the ultrasonic vibration is transferred directly from the patterned horn to the substrate. On the contrary, the indirect patterning process uses a plain horn, and the micro-patterns are engraved on a mold that is located below the substrate. Thus, the micro-patterns are replicated as an indirect manner. In this study, these direct and indirect patterning processes are compared in terms of the replication characteristics. Additionally, the possibility of double-side patterning is also discussed in comparison with the conventional single-side patterning process.