• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.2
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• pp.140-148
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• 2000

In this paper, using surface micromachining technology with thick photoresist and aluminum, an SLM(Spatial Light Modulator), which is applied to the fields of adaptive optics and pattern recognition system, was fabricated and the electromechanical properties of the fabricated micro SLM are measured. In order to maximize fill-factor and remove mechanical coupling between micro SLM actuators, the micro SLM is composed of three aluminum layers so that spring structure and upper electrode are placed beneath the mirror plate, and $10\times10$ each mirror plate is individually actuated. Also, the micro SLM was designed to be able to modulate phase and amplitude of incoming light in order to have a continuity of phase modulation of incoming light. In the case of amplitude and phase modulation, maximum vertical displacement is 4$\mum$, and maximum angular displacement is $\pm4.6^{\corc}$ respectively. The height difference of the fabricated mirror plate was able to be reduced to 1100A with mirror plate planarization method using negative photoresist(AZ5214). The electromechanical properties of the fabricated micro SLM were measured with the optical measurement system using He-Ne laser and PSD(position sensitive device).

• The Journal of Korea Robotics Society
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• v.9 no.3
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• pp.154-159
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• 2014

The Global Positioning System (GPS) is widely used to aid the navigation of aerial vehicles. However, the GPS cannot be used indoors, so alternative navigation methods are needed to be developed for micro aerial vehicles (MAVs) flying in GPS-denied environments. In this paper, a real-time three-dimensional (3-D) indoor navigation system and closed-loop control of a quad-rotor aerial vehicle equipped with an inertial measurement unit (IMU) and a low-cost light detection and ranging (LIDAR) is presented. In order to estimate the pose of the vehicle equipped with the two-dimensional LIDAR, an octree-based grid map and Monte-Carlo Localization (MCL) are adopted. The navigation results using the MCL are then evaluated by making a comparison with a motion capture system. Finally, the results are used for closed-loop control in order to validate its positioning accuracy during procedures for stable hovering and waypoint-following.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.562-567
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• 2006

Micro-alloyed steel or heat-treatment-free used in clean technology have been replacing for conventional quenched-and-tempered structural steels since the micro-alloyed forging steel was developed in early 1970s in Germany for saving money of heat treatment, simplified process, short delivery and good productivity. In this paper, ball stud assembled in steering system for automobile was selected to compare conventional process making heat treatment with new process using high strength micro-alloyed steel without heat treatment. The conventional process for ball stud was composed of a total of 6 steps including upsetting, forward extrusion, machining, burnishing and tread rolling with heat treatment and shot blasting. As opposed to conventional process, newly proposed process for ball stud using the clean technology without heat treatment is simplified such as forward extrusion, heading, upsetting, forming having a flange shape and tread rolling. Also net shape forming process to achieve specified process not to include machined step fur manufacturing the ball stud was applied to newly simplified process since micro-alloyed steel is difficult to be formed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.2
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• pp.163-168
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• 2015

The conventional simple-injection and unilateral-learning methods have the great disadvantages in special education outcomes for intellectual disabilities student. In this paper, we propose a digital micro-mirror system that learners themselves can manipulate the contents by using the various technology on user-interaction and augmented reality. Through the verification tests conducted by special education professionals, it is confirmed that the proposed commercial system can be used as a useful system in the special learning fields requiring high immersion.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1239-1248
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• 2018

This paper proposes a fault tolerant and high efficiency operation algorithm for a 4 LEG DC/DC converter for a battery energy storage system(BESS) forming a main power source in a standalone DC micro grid. The BESS for the main power supply in the stand-alone DC micro-grid is required to operate at high speed according to fault tolerant control and load by operating at all times. Fault-tolerance control changes the short-circuit fault to an open-circuit fault by using a fuse in case of leg fault in 4 legs, and operates stably through phase shift control. In addition, considering the loss of the power semiconductor, the number of LEG operation is adjusted to operate at high efficiency in the full load region. In this paper, fault tolerant control and high efficiency operation algorithm of DC/DC converter for BESS in standalone DC micro grid is presented and it is proved through simulation and experiment.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.603-607
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• 2002

Recently, the need leer transporting and manipulating minute amount of fluids in microscale channels (so-called micro-fluidics) has been increasing, especially in biotechnology and biochemical processing. This work demonstrates that the mechano-chemical process which consists of mechanical abrasive action combined with chemical process can be used to fabricate micro-fluidic channels more rapidly and cost effectively than other methods. In this work, capillary filling of fluids in micro-channels was investigated by theoretical approaches and experiments. From the experimental results, it is expected that a complex micro-fluidic system can be fabricated using the micro- fabrication technique and microsystem packaging method described in this work.

• Transactions of Materials Processing
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• v.15 no.9 s.90
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• pp.692-696
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• 2006

Micro fabrication of polymeric materials becomes increasingly important. And it is considered as a low-cost alternative to the silicon or glass-based Micro Electro-Mechanical System(MEMS) technologies. In the present study, micro channels were fabricated via LiGA(Lithographie, Galvanoformung, Abformung) process used for Capillary Electrophoresis(CE) chip. Taguchi method was applied to investigate the effects of process conditions in injection molding(melt temperature, injection speed, mold temperature and packing pressure) on the transcription characteristics of the micro channel. It was found that the skin layer disturbs a formation of micro channel. Furthermore, mold temperature and injection speed were two important factors to affect the replication characteristics of micro channel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.526-535
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• 2018

Recently, in order to reduce the $CO_2$ emission in the island area, countermeasures to operate power system in a stable manner are being researched due to decrease of the operation rate in diesel generators and the increase of renewable energy sources. The phenomenon of energy sinking can be occurred if the output of renewable energy sources is larger than customer loads. Voltage of CVCF(constant voltage & constant frequency) battery could be increased rapidly according to the condition of SOC(state of charge) and blackout could be occurred due to shut-down of CVCF inverter, at carbon free island micro-grid based on the CVCF inverter. In order to overcome these problems, this paper proposes a transient operation algorithm in CVCF based micro-grid which in advance prevents shut-down of CVCF inverter during the energy sinking. And also this paper proposes the modeling of micro-grid including CVCF inverter, PV system, customer load using PSCAD/EMTDC S/W. From the results of micro-grid modeling based on the proposed algorithm, it is confirmed that CVCF based micro-grid can properly prevent shut-down of CVCF inverter according to SOC and battery voltage of CVCF inverter when energy sinking is occurred.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1125-1125
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• 2001

Micro-scale test methods are producing small-sample size where the conventional physical and chemical tests can not be used (high standard deviation, uncertain sampling conditions, low repeatability). Different small-scale test methods were developed recently for determination of physico-chemical, functional, rheological properties of wheat or wheat dough using miniaturized instruments with sophisticated sample preparation/handling and mechanics (RVA, 2 g mixograph, micro-Z-arm mixer, small-scale noodle maker, micro-baking method etc.). The small-scale methodologies can be used as basic research tools or as technology supported measurements and can be also essential in the early selection for quality traits in breeding programs. The milling as a sample preparation step is essential procedure providing good quality flour or semolina samples from small amount of grain (5-10 g) in a reproducible and reliable way. The aim of present study was to use NIR as quality control tool, and to evaluate the recently developed and manufactured micro-scale lab mill (FQC-2000) produced by Inter-Labor Co. Ltd., Hungary. The milling characteristics of the new instrument were compared to other laboratory mills and the effects of milling action on the chemical composition of fractions were analysed. The fractions were tested with both chemical and near infrared spectroscopic methods. The micro-scale milling resulted significantly different yields, particle size distributions and different fractions from compositional point of view. The near infrared spectra were sensitive enough to distinguish the fractions obtained by different milling procedures. Quantitative NIR calibration equations were developed and tested in order to measure the chemical composition of characteristic milling fractions. Special qualification procedure the PQS (Polar Qualification System) method was used for detecting the differences between fractions obtained by macro and micro-milling procedures. The results and the limitations of PQS method in this application will be discussed.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1444-1446
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• 2005

Recently most machineries have been small size and mobile type. And human body insertion type endoscope and micro robot technology has been developed. Then the motors used in this field are developed in micro size such as about 2mm in diameter. The structure of this motor is similar to a general brushless DC(BLDC) motor but because of small size there is no position sensor such as hall sensor. In this paper, a design and fabrication result of an ultra-small brushless DC motor is presented. This motor is designed to 3-phase coreless winding and operated with sensor-less type driver. Test results confirmed the feasibility of the proposed motor drive system design.