• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.64-72
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• 2014

In the past, prism patterns have been linear triangular shapeswith a $90^{\circ}$ angle; however, new micro prism patterns having acute angles or obtuse angles have recently been the subject of demandin the display, lighting and photovoltaic industries. Micro-cutting experiments for micro-prism patterns having $60^{\circ}$, $90^{\circ}$, and $120^{\circ}$ angles on an electroplated Ni mold were performed and it was found in this study that the specific cutting resistance increased with a decrease in the tool angles (prism pattern angles). The cause of this variation had been thought to be the increase of the ploughing force due to tip rounding and the friction force due to the edge effect. However, the depth of the cut was large enough that it was possible to neglect these effects. Therefore, this study introduced the concept of representative stress of indentation. The measured stress was varied according to the indentation depth eventhoughthetestedspecimenswereidentical ; the varied stress was termed the representative stress. According to indentation theory, the strain that the Ni mold experienced increased with a decrease in the tool angle. Based on the stress-strain relationship, higher strain means higher stress and higher specific cutting resistance. Therefore, the specific cutting resistance was higher at smaller tool angles that had higher strain and stress.

• Design & Manufacturing
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• v.17 no.4
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• pp.1-7
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• 2023

In the fabrication of curved multi-display glass for automotive use, the surface roughness of the mold is a critical quality factor. However, the difficulty in detecting micro-cutting signals in a micro-machining environment and the absence of a standardized model for predicting micro-cutting forces make it challenging to intuitively infer the correlation between cutting variables and actual surface roughness under machining conditions. Consequently, current practices heavily rely on machining condition optimization through the utilization of cutting models and experimental research for force prediction. To overcome these limitations, this study employs a surface roughness prediction formula instead of a cutting force prediction model and converts the surface roughness prediction formula into experimental data. Additionally, to account for changes in surface roughness during machining runtime, the theory of position variables has been introduced. By leveraging artificial neural network technology, the accuracy of the surface roughness prediction formula model has improved by 98%. Through the application of artificial neural network technology, the surface roughness prediction formula model, with enhanced accuracy, is anticipated to reliably perform the derivation of optimal machining conditions and the prediction of surface roughness in various machining environments at the analytical stage.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.113-119
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• 2022

In order to improve the mechanical reliability of next-generation electronic devices including flexible, wearable devices, a high level of mechanical reliability is required at various flexible joints. Organic adhesive materials such as epoxy for bonding existing polymer substrates inevitably have an increase in the thickness of the joint and involve problems of thermodynamic damage due to repeated deformation and high temperature hardening. Therefore, it is required to develop a low-temperature bonding process to minimize the thickness of the joint and prevent thermal damage for flexible bonding. This study developed flexible laser transmission welding (f-LTW) that allows bonding of flexible substrates with flexibility, robustness, and low thermal damage. Carbon nanotube (CNT) is thin-film coated on a flexible substrate to reduce the thickness of the joint, and a local melt bonding process on the surface of a polymer substrate by heating a CNT dispersion beam laser has been developed. The laser process conditions were constructed to minimize the thermal damage of the substrate and the mechanism of forming a CNT junction with the polymer substrate. In addition, lap shear adhesion test, peel test, and repeated bending experiment were conducted to evaluate the strength and flexibility of the flexible bonding joint.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3056-3061
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• 2007

The technology of AC solenoid valves is now considered as a core technology in the fields of the production line of semi-conductor chips and the micro fluid chips for medical applications. And AC solenoid valves, which operate by compressed air, are characterized by high speed response, great repeatability and that the pressure on the cross sectional area of poppet is kept constant regardless of the fluctuation of the pressure exerted on the ports. In this study, AC solenoid valves that posses the high-speed responsibility and the high rate of flow have designed and analyzed through the law of equivalent magnetic circuit and Finite Element Method (FEM) respectively. In case of poppet, Flow field characteristic was analyzed by the variation of poppet and it was able to display flow field by changing the location of the poppet. Also, we verified possibility of the design through the static and dynamic pressure and the 3D distribution curve of the force by working the front poppet.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.168-171
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• 2016

There has been growing interest and rapid development in transparent electrode films, which are flexible and light and used in mobile, simple information, and electronic devices, and based on recent advancements in nano technology, information technology, and display technology. In particular, studies on developing such films with both high conductivity and high transmittance of visible rays are highly in demand for commercialization. In this study, transparent electrode films were developed for IT using micro patterns that show sheet resistance less than 10 Ω/□, adhesive strength more than 98%, and light transmittance more than 90%. The results of applying a surface emission gradient minimization (Honey Comb) technology to the films was the verification of the sheet resistance, adhesive strength, and light transmittance satisfying the target level of this study through Imprinting and Remolding processes.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1024-1026
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• 2004

We have developed the five mask $PMOS^1$ and the six mask CMOS process architecture for poly-Si TFT. In order to have a competitive process with that for a-Si TFT, the simple co-planar electrode structure whose data line electrode and pixel electrode are on the same plane was adopted. In addition, RGB + White four color $technology^2$ were applied to achieve high aperture ratio and transmittance. Using the aforementioned process architecture and four color technology, 2.0 inch qCIF transmissive micro-reflectance (TMR) device was successfully fabricated.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1185-1187
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• 2004

We have studied a liquid crystal (LC) mode, named locked super homeotropic (LSH), where the LCs aligned homeotropically are locked by surrounding walls such as cubic, hexagonal and cylinder. In the device, the vertically aligned LCs tilt down symmetrically around the center of the cell when a voltage is applied and thus it exhibits wide viewing angle. In addition, since the LCs is locked in micro domains the LCs do not flow to the bottom of the panel by gravity.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1125-1131
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• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on the two kinds of polyimide (PI) surfaces using thin plastic substrates. The NLC pretilt angles generated on thin plastic substrates are higher than that on the glass substrate. We study that AFM (atomic force microscope) image of rubbed PI surface with polymer film has formed the micro-groove. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer are almost the same as that of the TN-LCD with a rubbed PI surface based on glass.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.331-333
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• 2004

In this study, we implement the multiple frequency bioelectrical impedance analysis system for body composition analysis. Overall system consists of : 1) conductivity electrodes to contact with hands and foots, 2) multiple frequency alternating current signal generator for generating 5, 50, 250kHz frequency and 800uA contained alternating current signal, 3) voltage signal detector, 4) phase signal detector, 5) key-pad to input individual information, 6) micro controller for data processing, 7) LCD for processed data to display, 8) system power, We explain the architecture of the system and required theory to implement the system. Finally, experimental results are illustrated to show the performance of the system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.69-72
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• 2007

Cellulose is a beneficial material that has low cost, lightweight, high compatibility and biodegradability. Recently electroactive paper (EAPap) on cellulose base was discovered as a smart material and actuator through ion migration and piezoelectric effect. Furthermore cellulose has a potentiality to apply the display material, because of its high reflectivity, flexibility and high transmittance. The various shapes and height patterns of the Cellulose acetate (CA) solution, such as circle and honeycomb patterns, were fabricated and observed by field emission scanning electron microscope (FESEM, S4300 Hitachi). The resulting pattern showed uniform size in the large area without defect. After stretching the CA film with saponification process in the sodium methoxide in methanol solution, Most of the compositions become one directional ordered nanofibers below 50nm.