• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.674-675
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• 2016

In this paper, we propose a manufacturing process model of Internet of Things devices using a Printed Circuit Board (PCB)-mounted RFID tag chip for reducing electronic wastes. Electrical and electronic products require a PCB surface mount and many examination. Also, conventional barcode systems cannot provide traceability management in PCB manufacturing before finishing Surface Mount Technology (SMT) process. The proposed process model does not require workers' attaching and detaching process unlike barcode systems. Also, RFID tag chip can record all the data in manufacturing steps. Thus, the number of connections to a database management system (DBMS) can be reduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.427-427
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• 2007

The global applications of aspherics surfaces will expand rapidly on the electronics, optical components, communications, aerospace, defense, and medical optics devices etc. Especially, Asymmetric aspheric prism lens is one of the important parts in HMD(Head Mounted Display) because it affects dominantly on the optical performance of HMD. The mold core is the most important device to produce the plastic lenses by injection molding method. In this study, the mold cores for asymmetric aspheric prism lens were processed using fly-cutting method which is kind of the ultra precision processing and form accuracy and surface roughness of the cores were measured.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.1
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• pp.34-37
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• 2010

0.25 mm thickness super thin surface mounted device LED Lamp is developed with PCB type lead frame in which BT (Bismaleimide Triazine) resin is used. BT resin is removed by a laser beam in order to reduce the thermal resistance below $1\;^{\circ}C/W$ and transfer molding is used with silicone. Compared to conventional 0.4 mm thickness LED lamp, the developed LED lamp can be derived in high current and the luminance of the LED lamp is increased up to 240 mA.

• Current Optics and Photonics
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• v.1 no.5
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• pp.474-490
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• 2017

Since the recent slowdown in the smartphone market, studies for wearable devices are briskly being carried out to find new markets, such as virtual reality devices. In this paper, a head-mounted display (HMD) which provides expanded virtual images before human eyes by enlarging images of a small display was designed, and the tolerance analysis method for a focus-adjustable HMD based on afocal optical systems was studied. There are two types of HMDs: a see-through type that allows the user to view the surroundings, and a see-close type where the user can only view the display screen; the former is used in this study. While designing the system, we allowed a lens within the system to be shifted to adjust its focus from +1 to -4 D (diopters). The yield of the designed systems was calculated by taking the worst-case scenario of a uniform distribution into account. Additionally, a longitudinal aberration was used rather than MTF for the tolerance analysis with respect to system performance. The sensitivity of the designed system was calculated by assigning a certain tolerance, and the focus lens shift was calculated to adjust the image surface variations resulting from the tolerance. The smaller the tolerance, the more expensive the unit price of the products. Very small tolerances may even be impossible to fabricate. Considering this, the appropriate tolerance was assigned; the maximum shift of the focus lens in which the image surface can be adjusted was obtained to find the changes in aberration and a good yield.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.99-104
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• 2003

A precision displacement measurement system of 3-DOF micro motions is proposed in this paper. The measurement system is composed of two diode lasers, two quadratic PSDs, two beam splitters and a sphere whose surface is highly reflective. In this measurement system, the sphere reflector is mounted on the platform of positioning devices whose 3-DOF translational motions are to be measured, and the sensitive areas of two PSDs are oriented toward the center point of the sphere reflector. Each laser beam emitted from two diode laser sources is reflected at the surface of sphere and arrives at two PSDs. Each PSD serves as a 2-dimensional sensor, providing the information on the 3-dimensional position of the sphere. In this paper, we model the relationship between the outputs of two PSDs and 3-DOF translational motions of the sphere mounted on the object. Based on a deduced measurement model, we perform measurement simulation and evaluate the performance of the proposed measurement system: linearity, sensitivity, and measurement error. The simulation results show that the proposed measurement system can be valid means of precision displacement measurement of 3-dimensional micro motions.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.112-123
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• 1994

In this paper, inspection and subpixed alignment algorithms of SMD's (Surface Mounting Devices) using fuzzy morphology are proposed. First, camera calibration is performed and then the inspection algorithm detects defects such as lead bending and breaking using the ruler generated by fuzy morphology. The SMD having no defects is tested whether it is mounted in the specified position or not. The proposed subpixel alignment algorithm detects accurately orientation and position using subpixel interpolation. It consists of two parts: preprocessing and main processing steps, in which corner points and coarse orientation of a SMD are detected, and interpolation is used to obtain final parameters with wubpixel accuracy. The computer simulation shows that the proposed algorithms give more accurate parameters, and they can be applied to fast and accurate automatic surface mounting systems.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.16 no.28
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• pp.1-8
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• 1993

Electrical or electronic products have been becoming smaller and high integrated recently, with printed circuit boards(PCB's) being the key components for these products. The introduction of new technology of surface mounted devices(SMD) opens new ways towards high integration on the PCB. Many plants in eletronical industry which produce high variety of PCB's to meet the demands of customer orders require flexibility in PCB's production lines. This survey paper describes the related optimization problems and solution methods to the automated surface mount technology(SMT) assembly lines, and provides with the research direction for improving flexibility.

• Laser Solutions
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• v.14 no.2
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• pp.8-12
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• 2011

As the aged population grows around the world, many medical instruments and devices have been developed recently. Among the devices, a drug delivery stent is a medical device which requires precision machining. Conventional drug delivery stent has problems of residual polymer and decoating because the drug is coated on the surface of stent with the polymer. If the drug is impregnated in micro hole array on the surface of the stent, the problem can be solved. Micro sized holes are generally fabricated by laser machining; however, the fabricated holes do not have an enough aspect ratio to contain the drug or a good surface finish to deliver it to blood vessel tissue. To overcome these problems, we propose a vibration-assisted machining mechanism with PZT (Piezoelectric Transducers) for the fabrication of micro sized holes. If the mechanism vibrates the eyepiece of the laser machining head, the laser spot on the workpiece will vibrate vertically because objective lens in the eyepiece shakes by the mechanism's vibration. According to the former researches, the vibrating frequency over 20kHz and amplitude over 500nm are preferable. The vibration mechanism has cylindrical guide, hollowed PZT and supports. In the cylinder, the eyepiece is mounted. The cylindrical guide has upper and low plates and side wall. The shape of plates and side wall are designed to have high resonating frequency and large amplitude of motion. The PZT also is selected to have high actuating force and high speed of motion. The support has symmetrical and rigid characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.135-138
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• 2002

VCO(Voltage Controlled Oscillator) is one of the main components governing the size, performance and power consumption of telecommunication devices. As the devices become much smaller, VCO need to have much smaller size with better characteristics. Buried type passive components of L,C,R were developed previously and the structure of these components are good for minimizing the size of VCO. Our own library of passive components is used in simulation and fabrication of VCO circuit, and surface mounted components like varactor diode are analysed using the measurement circuit designed by ourselves. Two-Dimensional simulation of VCO circuit and local three-Dimensional structure simulation are performed and their relation is obtained. In structure of multi-layered VCO, some components governing the characteristics of VCO are selected and placed on the top of oscillator for the good tuning process. In resonator part, the stripline structure and low loss glass/ceramic material are used to get higher Q value. In our research, a VCO oscillates in the 2.3∼2.36 GHz band is developed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2687-2694
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• 2002

A precision displacement measuring system is proposed, which can detect the 3-DOF translational motions of precision positioning devices. The optical system, which is composed of two diode-laser sources and two quadratic PSDs, is adapted to detect the position of the spherical reflector usually mounted on the platform of positioning devices. Each of the laser beams from diode-laser sources is reflected at the highly reflective surface of the sphere; hence, the 3-dimensional position of the sphere causes the directional change of the reflected beams, which is detected by the PSDs. In this paper, we define the relationships between the output values of the two PSDs and the 3-DOF translational motions of the sphere. Based on a deduced measurement model, we perform measurement simulation and evaluate the performance of the proposed measurement system: linearity, sensitivity, measuring range, and measurement error. The results show that the proposed measuring method is very useful for the measurement of the precision displacement of 3-DOF micro motions.