• Composites Research
• /
• v.15 no.6
• /
• pp.24-29
• /
• 2002

For the development of all composite unmanned aerial vehicle(UAV), the consideration for manufacturing in design phase and events in composite parts fabrication, subassembly and final assembly are summarized. In design phase, to maximize the advantages of composite material such as cocuring, cobonding and secondary bonding for manufacturing, the advanced structural concept is introduced. For the curing of designed parts, the manufacturing tools for composite parts are designed and manufactured. The assembly jigs are designed to meet dimensional tolerance requirements of the vehicle structure. And the inspection criteria are established and applied for the manufacturing. Technical data for inspection items and methodologies are summarized to utilize for the exclusive specifications of the manufacturing sequence.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.04b
• /
• pp.129-132
• /
• 2004

This paper describes the design, fabrication and characteristics of a piezoelectric valve using MCA(Multilayer ceramic actuator). The MCA valve, which has the buckling effect, consists of three separate structures; MCA, a valve actuator die and an a seat die. The design of the actuator die was done by FEM modeling and displacement measurement, respectively. The valve seat die with 6 trenches was made, and the actuator die, which is driven to MCA under optimized conditions, was also fabricated. After Si-wafer direct bonding between the seat die and the actuator die, MCA was also anodic bonded to the seat/actuator die structure. PDMS sealing pad was fabricated to minimize a leak-rate. It was also bonded to seat die and SUS package. The MCA valve shows a flow rate of 9.13 sccm at a supplied voltage of 100 V with a 50 % duty cycle, maximum non-linearity was 2.24 % FS and leak rate was $3.03{\times}10^{-8}\;pa{\cdot}m^3/cm^2$. Therefore, the fabricated MCA valve is suitable for a variety of flow control equipment, a medical bio-system, automobile and air transportation industry.

• Design & Manufacturing
• /
• v.13 no.4
• /
• pp.17-22
• /
• 2019

Currently, studies on weight reduction and fuel efficiency increase are the most important topics in the automotive industry and many studies are under way. Among them, weight reduction is the best way to raise fuel efficiency and solve environmental pollution and resource depletion. Materials such as aluminum, magnesium and carbon curing materials can be found in lightweight materials. Among these, research on improvement of bonding technology and manufacturing method of materials and improvement of material properties through study of ultrahigh strength steel sheet is expected to be the biggest part of material weight reduction. As the strength of the ultra hight strength steel sheet increases during forming, it is difficult to obtain the dimensional accuracy as the elastic restoring force increases compared to the hardness or high strength steel sheet. It is known that the spring back phenomenon is affected by various factors depending on the raw material and processing process. We have conducted analytical evaluations and studies to analyze the springback that occurs according to the cross-sectional shape of the ultra high tensile steel sheet.

• Journal of the Korean Society for Precision Engineering
• /
• v.34 no.2
• /
• pp.77-81
• /
• 2017

CP (Commercially Pure) titanium has been widely used in various industries such as in energy plants and bio-materials because of an excellent corrosion resistance and its non-toxicity to the human body. But there are limitations for usage as structural materials due to low strength. The tensile properties of CP titanium could be improved by microstructure refinement such as in a SPD (Severe Plastic Deformation) process. However, high strengthening of CP titanium wire is impossible by SPD processes like ECAP (Equal Channel Angular Pressing), HPT (High-Pressure Torsion), and the ARB (Accumulative Roll Bonding) process. The study purposes are to increase the strength of CP titanium wire by optimization of the cold drawing process and the harmonization with mechanical properties by heat treatments for the next forming process. The optimization process was investigated with regard to the design of drawing dies and the reduction ratio of cross sections. The elongations of high strength CP titanium were controlled by heat treatment.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.3_1spc
• /
• pp.504-508
• /
• 2013

This paper describes in detail the life prediction models and simulations of thermal fatigue under different mold compounds and chip sizes for wafer-level embedded SiP. Three-dimensional finite element models are built to simulate the viscoplastic behaviors for various mold compounds and chip sizes. In particular, the bonding parts between a mold and silicon nitride (Si3N4) are carefully modeled, and the strain distributions are studied. Three different chip sizes are used, and the effects of the mold compounds are observed. Through the numerical studies, it is found that type-C, which has a relatively lower Young's modulus and higher CTE, has a better fatigue life than the other mold compounds. In addition, the $4{\times}4$ chip has a shorter life than the $6{\times}6$ and $8{\times}8$ chips.

• Transactions of the Society of Information Storage Systems
• /
• v.2 no.3
• /
• pp.163-168
• /
• 2006

Small form factor optical pickup (SFFOP) corresponding to BD specifications is strongly proposed for the next-generation portable storage device. In order to generate SFFOP, small sized optical pickup has been fabricated. We have developed a small sited optical pickup that is called the integrated optical pickup (IOP). The fabrication method of this system is mainly dependant on the use of the wafer based micro fabrication technology, which has been used in MEMS process such as photolithography, reactive ion etching, wafer bonding, and packaging process. This approach has the merits for mass production and high assembling accuracy. In this study, to generate the small sized optical pickup for high recording capacity, IOP corresponding to BD specifications has been designed and developed, including three main parts, 1) design, fabrication and evaluation of objective lens unit, 2) design and fabrication of IOP and 3) evaluation process of FES and TES.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.37 no.3
• /
• pp.63-71
• /
• 2000

Infrared (IR) detector chip, which detects the IR radiation from all of the objects and converts to image signal, is usually fabricated using hybrid bonding technology with detector away and readout integrated circuit (ROIC). In this study, we designed the readout circuit and simulated its operations. Fabricating readout circuit chips, we measured operation results satisfying its design requirements in 6V supply voltage. After we mount the IR detector chip in the manufactured thermal image system, thermal images were implemented. The obtained thermal images for high and room temperature target objects are sufficiently recognizable. Using the low noise thermal Image system, we expect to obtain thermal images with higher temperature resolution.

• Korean Journal of Computational Design and Engineering
• /
• v.8 no.2
• /
• pp.115-121
• /
• 2003

A new Layered Manufacturing(LM) system, named PaperMill, is developed applying micro milling technology. A micro endmill(127 11m in diameter) is introduced as the cutter of build material. The selected build material for this system is an adhesive-coated paper roll which provides advantages such as good bonding between layers, machinability, and low material cost. A 3-axis CNC controller and three step-motors are used for the movement of X-Y-Z table of the system. For simplicity of the control of mechanism, the control system for feeding the paper roll is uncoupled from CNC controller. Two code converters are developed for the toolpath generation of the new LM system. The NC converter generates a set of NC codes for PaperMill using commercial CAM software while the SML converter generates an NC code from Quickslice's SML format. The NC codes generated from the converters consist of a series of profile data and trigger code for paper feeding. Two sample gears were fabricated to prove the concept of the system, which shown that the dimensional errors of the fabricated gears is under 3.4 percent.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.5
• /
• pp.563-569
• /
• 1996

Degradation of $Zn_3N_2$ films is studied by using several analytical techniques. Polycrystalline $Zn_3N_2$ films prepared by reactie rf magnetron sputtering are kept in the air. Electrical and optical properties are measured by using van der Pauw technique and double-beam spectrometry. Structure and chemical bonding states are studied by X-ray diffraction(XRD), Fourier transfer infrared ray spectroscopy(FT-IR) and X-ray photoelectron specroscopy (XPS). Significant differences are observed in optical properties between the degraded film and the ZnO film. XRD analysis reveals that the degraded film contains very small ZnO grains because very weak and broad ZnO peaks are observed. XPS and FT-IR measurements reveal the formation of $Zn(OH)_2$ in the degraded film. The existence of N-H bonds in degraded films is exhibited from the N 1s spectra. $Zn_3N_2$ change into the mixture of ZnO, $Zn(OH)_2$ and an ammonium salt.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2006.05a
• /
• pp.54-58
• /
• 2006

This paper deals with primary consideration in down-conductor system and earth-termination system design of apartments. For down-conductor system, steelworks within reinforced concrete apartment structures have the electrical continuity, however, lashing is not suitable for lightning-current-carrying connections. So this paper suggest that the additional dedicated conductors should be installed and they are should be lashed to the reinforcement steel. Also this paper suggested the foundation earth electrode and global earth system as the earth-termination system of the apartments. But perfect bonding system is essential in lightning protection system to avoid life hazard and to protect electronic equipments.