• 한국강구조학회 논문집
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• 제16권2호통권69호
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• pp.201-213
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• 2004

본 논문에서는 유전자 알고리즘과 보-기둥 접합부, 부재, 그리고 구조물 전체의 재료 및 기하학적 비선형 거동을 고려할 수 있는 개선소성힌지해석 방법을 접목시킨 평면 반강접 강골조 구조물의 최적설계법을 제안하였다. 개선소성힌지해석에서는 강골조 구조물의 기하학적 비선형성을 고려하기 위해 보-기둥 요소의 안정함수를 사용하였으며, 재료적 비선형성을 고려하기 위해 잔류응력, 소성힌지, 반강접 접합부 그리고 기하학적 불완전성 등에 의한 점진적인 강성감소모델을 사용하였다. 최적설계시 마이크로 유전자 알고리즘과 재생산을 위한 개체 선택 도구로 토너먼트 선택방법을 사용하였으며, 적합도 함수는 목적함수 및 벌칙함수로 나타낸 무제약 함수값의 조합으로 구성하였다. 목적함수로는 구조물의 중량을, 제약조건으로는 하중-저항능력, 사용성, 연성도, 그리고 시공성에 관한 기준을 사용하였다. 강접 및 반강접 접합부를 갖는 강골조 구조물의 최적설계결과의 비교를 통해 본 연구에서 제시한 방법의 적합성을 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.582-587
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• 2004

Ultrasonic sensors are widely used in mobile robot applications to recognize external environments, because they are cheap, easy to use, and robust under varying lighting conditions. However, the recognition of objects using a ultrasonic sensor is not so easy due to its characteristics such as narrow beam width and no reflected signal from a inclined object. As one of the alternatives to resolve these problems, use of multiple sensors has been studied. A sequential driving system needs a long measurement time and does not take advantage of multiple sensors. Simultaneous and pulse coding driving system of ultrasonic sensor array cannot measure short distance as the length of the code becomes long. This problem can be resolved by multi-frequency driving of ultrasonic sensors, which allows multi-sensors to be fired simultaneously and adjacent objects to be distinguished. Accordingly, this paper presents a simultaneous and multi-frequency driving system for an ultrasonic sensor array for object recognition. The proposed system is designed and implemented using a DSP and FPGA. A micro-controller board is made using a DSP, Polaroid 6500 ranging modules are modified for firing the multi-frequency signals, and a 5-channel frequency modulated signal generating board is made using a FPGA. To verify the proposed method, experiments were conducted in an environment with overlapping signals, and the flight distances for each sensor were obtained from filtering of the received overlapping signals and calculation of the time-of-flights.

• 방사성폐기물학회지
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• 제3권1호
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• pp.17-21
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• 2005

방사선차폐 laser ablation 시스템을 레이저, 미세영역의 영상 확인을 위한 이미지 시스템, XYZ 이동장치와 조절기, ablation chamber, manipulator 및 여러 가지 광학부품들로 구성하였다. Ablation용 레이저는 UOB 및 tircaloy 시편으로부터 효율적으로 시료를 채취할 수 있도록 266 nm(6 mJ)까지 파장 변환이 가능한 Nd:YAG 레이저를 선정하였으며, 이미지 시스템은 직경 50 $\mu$m 크기의 crater를 판별할 수 있는 200 배율 이상의 규격을 갖춘 CCD 카메라로 선정하였다. 시편 미세이동장치는 XYZ방향으로 시편이동이 가능하고 최대 이동거리가 50 mm까지 , 그리고 최소 1$\mu$m 씩 정확하게 움직일 수 있는 장치로 선정하였다. 구성된 각 단위기기들에 대하여 광학 정렬을 수행한 후, 시료채취 부위를 50 $\mu$m씩 정확하게 이동하면서 레이저로 조사시킨 시료 표면을 CCD 카메라를 통하여 관찰한 결과, 표면에 생성된 crater는 원형임을 확인함으로써 단위기기별 성능을 확인할 수 있었다.

• 콘크리트학회논문집
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• 제23권4호
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• pp.503-509
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• 2011

ECC는 모르타르 매트릭스에 약 2% 이내 체적비의 합성 섬유를 보강하여 1축 인장 하에서 변형률 경화 거동과 다수의 미세균열을 발현하도록 제조한 높은 연성의 시멘트 복합 재료이다. 최근 ECC를 적용하는 연구가 구조물 보수보강 공법, 현장 타설 및 프리캐스트화 공법 등 다양한 형태로 진행되고 있으며, 특히 연성이 요구되는 구조 부재에 적용하고 하는 시도가 끊임없이 이루어지고 있다. 이 연구에서는 성능 저하된 철근콘크리트(RC) 보의 구조 성능 및 균열 제어 성능을 개선하기 위하여 ECC와 고장력 철근을 함께 활용하는 보강 공법을 다루고 있다. 이를 위하여 RC 보실험체를 제작 실험하여 구조 성능과 파괴 형태 등을 연구하였다. 실험 결과, ECC와 고장력 철근으로 보강된 RC보는 우수한 균열 제어 성능과 더불어 휨 내하력 및 휨 강성이 크게 향상되는 것으로 평가되었다. 이 연구 결과는 ECC와 고장력 철근을 활용한 보강 공법의 설계 및 현장 적용을 위한 기초 자료로 활용될 것이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.732-737
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• 2005

Distal 3D Real Object Duplication System(RODS) consists of 3D Scanner and Solid Freeform Fabrication System(SFFS). It is a device to make three-dimensional objects directly from the drawing or the scanning data. In this research, we developed an office type SFFS based on Three Dimensional Printing Process and a industrial SFFS using Dual Laser. An office type SFFS applied sliding mode control with sliding perturbation observer(SMCSPO) algorithm for control of this system. And we measured process variables about droplet diameter measurement and powder bed formation etc. through experiments. Also, in order to develop more elaborate and speedy system for large objects than existing SLS process, this study applies a new Selective Multi-Laser Sintering(SMLS) process and 3-axis dynamic Focusing Scanner for scanning large area instead of the existing $f\theta$ lens. In this process, the temperature has a great influence on sintering of the polymer. Also the laser parameters are considered like that laser beam power, scan speed, scan spacing. Now, this study is in progress to eveluate the effect of experimental parameters on the sintering process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.657-662
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• 2005

In this study, the deposition of micrometer-scale metallic interconnects on LCD glass for the repair of open-circuit type defects is investigated. Although there had been a few studies Since 1980 s for the deposition of metallic interconnects by laser-induced chemical vapor deposition, those studies mostly used continuous wave lasers. In this work, a third harmonic Nd:YLF laser (351nm) of high repetition rates, up to 10 KHz, was used as the illumination source and $W(CO)_6$ was selected as the precursor. General characteristics of the metal deposit (tungsten) such as height, width, morphology as well as electrical properties were examined for various process conditions. Height of the deposited tungsten lines ranged from 35 to 500 nm depending on laser power and scan speed while the width was controlled between $3\~50{\mu}$ using a slit placed in the beam path. The resistivity of the deposited tungsten lines was measured to be below 1 $O\cdot{\mu}m$, which is an acceptable value according to the manufacturing standard. The tungsten lines produced at high scan speed had good surface morphology with little particles around the patterns. Experimental results demonstrated that it is likely that the deposit forms through a hybrid process, namely through the combination of photolytic and pyrolytic mechanisms.

• 한국물환경학회지
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• 제26권6호
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• pp.1028-1033
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• 2010

Wastewater reuse for agricultural irrigation needs treatment and control of pathogens to minimize risks to human health and the environment. In order to evaluate the water quality of UV-treated reclaimed water, this study focused on the relationship between micro-pathogens and particulate matters. MS2 was selected as an index organism because it has similar characteristics to human enteric virus and strong resistance to UV disinfection. The turbidity and suspended solid (SS) were selected for test parameters. In this study, it was performed with different UV doses (30 and $60mJ/cm^2$) for estimation of the MS2 inactivation rate using collimated beam batch experiments in the laboratory. The experiment results by turbidity or SS concentration presented that the increased concentration of them lowered MS2 inactivation. At the turbidity (below 4.27 NTU) and SS (below 1.47 mg/L) of the low level range, the inactivation of 60 UV dose is higher than 30 UV dose. However, at the turbidity and SS of the high level, the increasing UV dose did not show apparent increasing the MS2 inactivation. In quantitative microbial risk assessment (QMRA), it can confirm the trend that $P_D$ and turbidity concentrations have positive correlationship at the low concentration, which was also observed in SS. The QMRA can be helpful in communication with public for safe wastewater reuse and be recommended.

• 한국가시화정보학회지
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• 제5권1호
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• pp.9-11
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• 2007

유(流)세포분석기(flow cytometer)는 일정한 체적 내에 존재하는 세포의 종류 및 개체 수 등을 계측하는 장비로써 생체에서 추출한 유액상태(혈액 또는 림프액)의 세포를 모세관(micro-channel)을 통과시킬 때 발생하는 산란 및 형광 빛을 이용하여 계측한다. 유세포 분석기는 신약의 투석 후 세포수의 증감, 암세포의 전이 및 세포주기의 분석 등을 연구하는 데 사용되며 현재 Becton-Dickinson's 등에서 상용화된 제품을 생산 판매하고 있으며, 계측을 위해서는 생체에서 세포를 추출해야 한다는 단점을 가지고 있다. Harvard 의과대학에서 최근에 개발한 생체 유세포분석기(In vivo Flow Cytometer)는 생체에서 세포를 추출하지 않고 세포의 수를 계측할 수 있다[1]. 레이저가 혈관의 특정한 부위에 조사되고 있고, 이곳을 세포가 통과하면서 발생하는 형광을 계측함으로써 주어진 시간 동안 특정세포군이 얼마나 지나가는 지를 계측할 수 있는 장비이다. 본 특별기사에서는 혈류 가시화 분야의 독자를 위해 최근에 "Optics Express"에 "In vivo imaging flow cytometer"라는 제목으로 최근에 개제된 논문의 내용을 하여 소개한다[2].

• The Korean Journal of Ceramics
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• 제7권1호
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• pp.36-40
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• 2001

In order to fabricate uncooled IR sensors for pyroelectric applications, multilayered thin films of Pt/PbTiO$_3$/Pt/Ti/Si$_3$N$_4$/SiO$_2$/Si and thermally isolating membrane structures of square-shaped/cantilevers-shaped microstructures were prepared. Cavity was also fabricated via direct silicon wafer bonding and etching technique. Metallic Pt layer was deposited by ion beam sputtering while PbTiO$_3$ thin films were prepared by sol-gel technique. Micromachining technology was used to fabricate microstructured-membrane detectors. In order to avoid a difficulty of etching active layers, silicon-nitride membrane structure was fabricated through the direct bonding and etching of the silicon wafer. Although multilayered thin film deposition and device fabrications were processed independently, these could b integrated to make IR micro-sensor devices.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.481-486
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• 2010

ENIG (electroless Ni immersion gold) is one of surface finishing which has been most widely used in fine pitch SMT (surface mount technology) and BGA (ball grid array) packaging process. The reliability for package bondability is mainly affected by interfacial reaction between solder and surface finishing. Since the behavior of IMC (intermetallic compound), or the interfacial reaction between Ni and solder, affects to some product reliabilities such as solderability and bondability, understanding behavior of IMC should be important issue. Thus, we studied the properties of ENIG with P contents (9 wt% and 13 wt%), where the P contents is one of main factors in formation of IMC layer. The effect of P content was discussed using the results obtained from FE-SEM(field-emission scanning electron microscope), EPMA(electron probe micro analyzer), EDS(energy dispersive spectroscopy) and Dual-FIB(focused ion beam). Especially, we observed needle type irregular IMC layer with decreasing Ni contents under high P contents (13 wt%). Also, we found how IMC layer affects to bondability with forming continuous Kirkendall voids and thick P-rich layer.