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적층조형과 직접주사방식을 결합한 광경화성 수지 기반의 신축성 촉각센서의 제작
우상구(Sang Gu Woo),이인환(In Hwan Lee),김호찬(Ho-Chan Kim),이경창(Kyung Chang Lee),조해용(Hae-Yong Cho) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.2
Many kinds of robots and machines have been developed to replace human laborin industrial and medical fields, as well as domestic life. In these applications, the device sneed to obtain environmental data using diverse sensors. Among such sensors, the tactile sensor is important because of its ability to get information regarding surface texture and force through the use of mechanical contact. In this research, a simple tactile sensor was developed using the direct writing of pressure sensitive material and layered fabrication of photocurable material. The body of the sensor was fabricated using layered fabrication, and pressure sensitive materials were dispensed between the layers using direct writing. We examined the line fabrication characteristics of the pressure sensitive material according to nozzle dispensing conditions. A simple 4 x 4 array flexible tactile sensor was successfully fabricated using the proposed process.
콘크리트 열화 진단의 LIBS 적용을 위한 실험적 연구
우상균,추인엽,윤병돈,Woo, Sang-Kyun,Chu, In-Yeop,Youn, Byong-Don 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 논문집 Vol.21 No.6
표준 시료의 분광 분석으로부터 획득한 각 원소별 파장 특성 값과 검사대상 미지 시료로부터의 파장 분석 결과를 비교함으로써 미지 시료에 함유된 원소의 정성 및 정량 분석을 가능하게 하는 것이 LIBS이다. 본 연구에서는 콘크리트 내구성에 영향을 미치는 주요 열화 요인을 규명하는 것에 대하여 LIBS의 적용 가능성을 실험적으로 분석하였다. 즉, LIBS를 통해 염화물, 황산염, 탄산화 모르타르 시험체에 대한 유해 열화인자 정량 검출 실험을 실시함으로써 콘크리트 열화 진단의 LIBS 적용 가능성을 연구하였다. 염화물과 황산염 시험체 각각에 대하여 LIBS 실험을 실시한 결과 농도가 증가할수록 염소 및 황 이온의 LIBS 스펙트럼 파장 강도가 선형적으로 증가하는 것을 알 수 있었다. 탄산화 시험체의 경우 탄산화 노출 기간에 따른 탄소 이온 LIBS 스펙트럼 파장 강도는 다소 비선형적으로 증가하는 것으로 나타났다. 이상의 실험결과로부터 콘크리트 열화 진단에 LIBS의 적용가능성을 부분적으로 확인할 수 있었으며, 콘크리트 탄산화의 경우 시멘트 자체에 탄소 성분이 함유되어 염화물 및 황산염 시험체의 정량 검출과는 다소 상이한 결과를 보인 것으로 추정된다. 따라서 콘크리트 탄산화에 대하여 LIBS를 적용하기 위해서는 보다 다양한 매개변수 연구가 수행되어야 할 것으로 사료된다. It is laser induced breakdown spectroscopy(LIBS) that enables qualitative and quantitative analysis of the elements contained in unknown specimen by comparing the wavelength characteristics of each element obtained from the spectral analysis of the standard specimen with the wavelength analysis results from unknown specimens. In this study, the applicability of LIBS to the analysis of major deterioration factors affecting concrete durability was experimentally analyzed. That is, the possibility of applying LIBS to the diagnosis of concrete deterioration by studying the quantitative detection of harmful deteriorating factors on chloride, sulfate and carbonated mortar specimens using LIBS was studied. As a result of LIBS test for each chloride and sulfate specimen, the LIBS spectral wavelength intensity of chlorine and sulfur ions increased linearly with increasing concentration. Carbon ion LIBS spectral wave intensities of carbonated specimens increased nonlinearly over the duration of carbonation exposure. From the above results, it can be partially confirmed that LIBS can be applied to the diagnosis of concrete deterioration. In case of concrete carbonation, it is presumed that carbon content is contained in the cement itself and is different from the detection of chloride and sulfate specimen. Therefore, it is considered that more various parameter studies should be performed to apply LIBS to concrete carbonation.
서로 다른 밀도를 갖는 탄소섬유강화 탄화규소 복합재료의 압흔응력에 의한 기계적 거동
이기성,김일겸,김태우,김세영,한인섭,우상국,Lee, Kee-Sung,Kim, Il-Kyum,Kim, Tae-Woo,Kim, Se-Young,Han, In-Sub,Woo, Sang-Kuk 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.4
In this study, we investigated the mechanical behavior of carbon fiber reinforced silicon carbide composites by indentation stress. Relatively porous and dense fiber reinforced ceramic composites were fabricated by liquid silicon infiltration (LSI) process. Densification of fiber composite was controlled by hardening temperature of preform and consecutive LSI process. Load-displacement curves were obtained during indentation of WC sphere on the carbon fiber reinforced silicon carbide composites. The indentation damages at various loads were observed, and the elastic modulus were predicted from unloading curve of load-displacement curve.
우상구(Sang Gu Woo),김호찬(Ho-Chan Kim),이경창(Kyoung-Chang Lee),조해용(Hae Yong Cho),이인환(In Hwan Lee) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
Many kinds of robots or machines have to help people safely through interacting with surrounding environments. In this regards, they have to get environmental data from outside using diverse sensors. Among the sensors, tactile sensor is important because of its ability of getting information such as surface texture and force by mechanical contact. In this research, simple tactile sensor was proposed using direct writing of pressure sensitive material as well as layered fabrication of PDMS. The pressure sensitive material was mixed with PDMS and MWCNTs. The body of the sensor was fabricated using layered fabrication. And among the layers the pressure sensitive materials were dispensed using direct writing. We examined the line fabrication characteristics of the pressure sensitive material according to the nozzle dispensing conditions. A simple 4 x 4 array flexible tactile sensor was fabricated successfully using proposed process.
탄산화에 노출된 철근콘크리트 구조물의 로그 및 정규 수명분포를 고려한 보수비용 해석
우상인(Sang-In Woo),권성준(Seung-Jun Kwon) 한국건설순환자원학회 2018 한국건설순환자원학회 논문집 Vol.6 No.3
지하구조물에 주로 발생하는 탄산화는 콘크리트 내부의 공극수의 pH감소에 따라 부식을 유발할 수 있으므로 많은 연구가 진행되고 있다. 그러나 이산화탄소로부터 표면을 보호하는 간단한 표면 보수방법을 통하여 구조물의 내구수명의 연장이 가능하다. 기존의 결정론적 유지관리 기법과는 다르게, 확률론적 유지관리 기법에서는 내구수명의 변동성이 고려될 수 있으나 정규분포만 다루고 있다. 본 연구에서는 정규분포 이외에 로그분포를 고려할 수 있는 수명-확률분포를 유도하였으며, 이를 기초로 다양한 수명-확률분포 함수를 고려한 보수비 산정기법을 제안하였다. 제안된 기법은 초기의 내구수명 분포 또는 보수재를 통하여 연장된 내구수명 분포가 정규 또는 로그분포를 가질 경우 목표내구수명의 연장에 따라 확률론적 기법을 통하여 보수비를 평가할 수 있다. 보수를 통한 내구수명이 로그분포를 가질 경우 효과적으로 보수비를 감소시킬 수 있으며, 장기 실험 또는 실태조사를 통하여 내구수명 분포가 정의될 수 있다면 더욱 합리적인 유지관리 계획을 수립할 수 있을 것으로 판단된다. Many researches have been carried out on carbonation, a representative deterioration in underground structure. The carbonation of RC (Reinforced Concrete) structure can cause steel corrosion through pH drop in concrete pore water. However extension of service life in RC structures can be obtained through simple surface protection. Unlike the conventional deterministic maintenance technique, probabilistic technique can consider a variation of service life but it deals with only normal distributions. In the work, life time-probability distributions considering not only normal but also log distributions are induced, and repair cost estimation technique is proposed based on the induced model. The proposed technique can evaluate the repair cost through probabilistic manner regardless of normal or log distribution from initial service life and extended service life with repair. When the extended service life through repair has log distribution, repair cost is effectively reduced. The more reasonable maintenance strategy can be set up though actual determination of life-probability distribution based on long term tests and field investigations.
촉각센서 적용을 위한 다중 벽 탄소나노튜브 혼합물의 성형
우상구 ( Sang Gu Woo ),이인환 ( In Hwan Lee ),조해용 ( Hae Yong Cho ) 충북대학교 산업과학기술연구소 2013 산업과학기술연구 논문집 Vol.27 No.1
The flexible sensors to mimic human tactile sensation have been focused widely. However, many of these sensors were fabricated through a series of complex processes. Furthermore, economically available sensors are cost ineffective. Recently, simple tactile sensor was proposed using flexible material and conductive material. That is, the conductive material is discharged on the flexible polymer substrate by direct injection technique. When the external pressure is applied to the sensor, the electrical signal of the conductive lines is changed. Consequently, to implement this kind of sensor it is essential to examine dispensing characteristics for the line fabrication. In this regards, we examined the line fabrication characteristics of MWCNT mixture according to the nozzle dispensing conditions. From the experimental results, it was found that the line width of MWCNT mixture decreases as the flow rate decreases and the nozzle moving speed increases.
Gel-Casting 및 마이크로파 기상반응소결에 의한 질화규소 세라믹 제조에 대한 연구(I) : Gel-Casting에 의한 실리콘 성형체의 제조
배강,우상국,한인섭,서두원,Bai, Kang,Woo, Sang-Kuk,Han, In-Sub,Seo, Doo-Won 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.5
By gel-casting, the silicon-polymer green bodies were prepared for silicon nitride ceramics, sintered by microwave gas phase reaction. Considering the viscosity and the idle time of slurries, we decided the operational conditions of related processes, and the optimum concentrations of raw materials powders, organic monomers, cross-linker, dispersant, initiator, and catalyst. So we could get the machinable green bodies, having about 50 MPa of bending strength without cracks by selecting drying conditions carefully.