• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.58-64
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• 2019

This study presents a novel method for preparing monodisperse polyethylene glycol diacrylate (PEGDA) microparticles in a dispensing needle based microfluidic device. The microfluidic devices are manufactured by manually assembling various off-the-shelf products without using additional equipment. In this microfluidic device, the volumetric flow rates of the dispersed phase of PEGDA solution and the continuous phase of oil are controlled to generate monodisperse PEGDA droplets. The PEGDA droplet contains photo-initiator thus it is crosslinked to microparticle by photopolymerization at the ends of the device. The particle size is easily controlled by adjusting the volume flow rate and the size of the microfluidic device. The monodispersity of the particles is calculated by a coefficient of variation of 2.57%. To demonstrate the biological applications of PEGDA particles, cells are encapsulated and observed for proliferation and viability.

• Applied Microscopy
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• v.42 no.2
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• pp.67-76
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• 2012

The biomimetic approach on the cuticular spinning nozzles of the major ampullate silk glands in the golden-web spider Nephila calvata has been attempted using various visualizing techniques of light and electron microscopes to improve the design of spinning nozzle for producing synthetic nanofibers spun from electrospinning apparatus. The major ampullate spigot which has the most effective nozzle system to produce nanofibers for dragline silk with high strength and elasticity is connected via the bullet type spigot on anterior spinneret with flexible terminal segment. The excretory duct which transports the liquid silk feedstock from ampulla to spigot is divided into 3 limbs by loops back on itself to form an S-shape morphology that is bundled in connective tissue. Final diameter of the nanofibers at nozzle was dramatically reduced by gradual narrowing of duct cuticle less than 10 times comparing to its original size of funnel region. Moreover, the funnel has a characteristic cuticular organization with porous microstructure which seems to be related to water removal from feedstock of silk precursors. High magnification electron micrographs also reveal the presence of the spiral grooves on the surface of the cuticular intima near the valve which presumed to reduce friction during rapid flow of liquid silk.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.71-77
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• 2014

Heavy rainfall induces many disasters including slope failure and infrastructure collapse. In this point of view, rainfall-simulated centrifugal model test can be a reasonable tool to evaluate the stability of geotechnical structure. In order to obtain the displacements of a model in centrifugal model test, in general, LVDT and laser displacement sensor are used. However, when the rainfall is simulated, the LVDT has the problem of excessive infiltration into the model ground, and the laser displacement sensor provides the measuring result with inaccuracy due to the dispersion of the laser radiation. Hence, in this study, horizontal displacement sensor for rainfall-simulated centrifugal model test was developed. This sensor produced with a thin elastic steel plate and gave the accurate relationship between the displacement and the strain.

• Applied Microscopy
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• v.33 no.4
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• pp.315-323
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• 2003

The fine structural characteristics of the spinnerets and spigots of the silk producing apparatus in the adult funnel-web spider, Agelena limbata, were analysed with the light and scanning electron microscopes. Silk producing apparatus of this spider was composed of three pairs of spinnerets (anterior, median, posterior) and four different types of spigots-ampullates, tubuliforms, pyriforms and aciniforms. By the examination of their ultrastructural characteristics, it has been revealed that each spigot on the spinnerets are connected through the typical silk gland within abdominal cavity. Among the three pairs of spinnerets, the posterior pairs were highly elongated and has most characteristic features. Two pairs of large ampullates were connected to anterior spinneret and another two pairs of small ampullates to median spinnerets. Spigots of the tubuliforms were observed only in female and were connected both of median and posterior spinnerets respectively. While spigots of the pyriforms were connected on the anterior spinnerets but aciniforms on both of median and posterior spinnerets respectively.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.590-596
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• 2016

Biopsy is a typical needle type intervention procedure performed under radiographic image equipment such as computed tomography (CT) and cone-beam CT. This minimal invasive procedure is a simple and effective way for identifying cancerous condition of a suspicious tissue but radiation exposure for the patients and interventional radiologists is a critical problem. In order to overcome such trouble and improve accuracy in targeting of the needle, there have been various attempts using robot technology. Those devices and systems, however, are not for full procedure automation in biopsy without consideration for tissue sampling task. A robotic end-effector of a master-slave tele-operated needle type intervention robot system has been proposed to perform entire biopsy procedure by the authors. However, motorized sampling adopted in the device has different cutting speed from that of biopsy guns used in the conventional way. This paper presents the design of a novel robotic mechanism and protocol for the automation of biopsy procedure using spring-triggered biopsy gun mechanism. An experimental prototype has been successfully fabricated and shown its feasibility of the automated biopsy sequence.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.985-993
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• 2006

The use of prefabricated concrete piles have been gradually increased in many construction sites. One of main works for building a concrete pile foundation is to crush a part of pile head which is compressed with more than $800kg/cm^2$. A pile cutting work is usually performed by a crusher and three to four skilled workers. Recent reports on the pile cutting work reveal that a lot of cracks which significantly reduce the strength of the pile and are frequently made during pile cutting operations and it is very repetitive and labor intensive work. To improve productivity, safety, and quality of the conventional concrete pile cutting work, the research on developing an automated concrete pile cutter has been performed. In this paper, sensing methods for detecting a pile cutting line are suggested with operation process algorithms. The suggested methods are very important to develop the automated pile cutter. A pilot-type of the automated pile cutter that adopt one of the suggested sensing methods, is developed and tested in a construction site.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1308-1309
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• 2011

스마트그리드가 출현함에 따라 향후 배전계통에 태양광, 풍력, 연료전지, 전력저장장치, 전기자동차(V2G) 등의 분산전원의 연계는 급속도록 증가할 것이며 더불어 배전계통은 더욱 더 복잡하게 될 것이다. 이로 인해 발생하는 가장 큰 문제는 계통의 전압변동 문제이다. 복잡한 전압변동 문제를 해결하지 못하면 스마트그리드 계통의 전력품질과 안정도에 악영향을 끼칠 것이다. 스마트그리드 계통 하에서 분산전원의 위치는 변전소 근처 전원단부터 부하 말단까지 전원사업자의 필요에 따라 설치하게 될 것으로 지금까지의 전압변동, 조류계산 등의 모델링 방법으로는 해결하지 못하는 문제가 발생하게 될 것이다. 이 논문에서는 분산전원 배전계통 연계 용량 확대를 위해 실 선로의 실시간 전압 측정값을 이용한 분산전원 연계 스마트그리드 계통의 통합 전압관리안정화 방법에 대해 제안하고자 한다.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.753-759
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• 2011

In this paper, we propose the direction of development for EOD robot. We collected and analyzed the opinions of EOD teams. In order to verify the opinions, we conducted QFD(Quality Function Deployment) analysis. Based on the QFD analysis, we work out the priority of EOD robot development. And we establish the goal of development(target system) and suggest the development direction of EOD robot on each issue.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.684-685
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• 2011

종래의 배전계통에 있어서의 전력조류는 변전소에서 선로 말단을 향한 단방향이었지만, 태양광전원이 연계된 경우에는 그 출력용량의 여부에 따라 양방향의 전력조류가 발생할 가능성이 있어, 계통운용상 여러 가지의 문제점이 야기될 수 있다. 따라서 본 논문에서는 태양광 전원 연계에 따른 정상상태 시와 각종 전력품질에 대한 문제점을 상세히 분석하기 위하여, 실계통의 특성을 모의한 태양광전원 평가 시뮬레이터를 제작하였다. 그리고 이 장치를 이용하여 역률, 선로길이, 태양광발 전량의 변동에 따른 계통의 다양한 운용특성시험을 수행하여 제안한 평가 시뮬레이터의 유용성을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.90-94
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• 1992

A portable multichannel functional electrical stimulation(FES) system for the fine control of the paralyzed extremities in spinal cord injury patients is described. This system is composed of a stimulation data creating system, a serial communication device, a 16-bit microprocessor, D/A converter of 32 channels and a display device. Stimulation patterns are created from analytical results of integrated EMGs during motion in normal subjects and are stored in the stimulation data creating system as data files. And then the stimulation patterns are sent to the memory in the portable multichannel FES system through serial communication interfacing device. Sophisticated fine control of paralyzed extrimities was realized by transmitting multichannel stimulation patterns to percutaneous intramuscular electrodes, which stimulate the motor function of paralyzed muscle simultaneously. Advantages of this system are as follws: 1) It is possible to modify stimulation patterns in accordance with the patient's situation. 2) This system is small and light.