탄소섬유판(CFRP Strip)으로 보강된 철근콘크리트 부재의 파괴거동 및 휨 거동 특성

임동환(Lim Dong Hwan),박성환(Park Sung Hwan) 대한토목학회 2008 대한토목학회논문집 A Vol.28 No.2A

본 연구는 탄소섬유판으로 보강된 철근콘크리트 부재의 휨 거동특성 및 파괴양상을 규명하고 또한 탄소섬유판 부착탈락 거동을 규명함에 그 목적이 있다. 이를 위하여 탄소섬유판의 형상, 섬유판 부착길이, 부착면적 등의 다양한 변수를 포함하는 실험연구가 수행되었으며, 초기 부착균열이 발생되는 부착탈락 기구를 규명 하였다. 본 실험결과 탄소섬유판으로 보강된 철근콘크리트 부재의 휨 강성은 보강되지 않은 보에 비해 현저하게 개선되며 최대 극한강도 증진율은 120% 이상인 것으로 나타났다. 또한 탄소섬유판 탈락 시 측정된 탄소섬유판의 인장변형율은 탄소섬유판의 극한 변형율의 36%에 해당되는 것으로 나타났으며, 탄소섬유판의 부착길이가 충분 할수록 보는 휨 균열로 야기되는 탄소섬유판의 계면 부착탈락으로 파괴됨을 알 수 있었다. 탄소섬유판의 계면부착탈락은 휨을 받는 구역에서 시작되어 보의 양 끝단으로 급격하게 전파되는 취성적인 파괴를 유도하는 것으로 나타났다. 본 연구에서는 탄소섬유판의 유효응력에 근거하여 탄소섬유판으로 보강된 철근콘크리트 부재의 휨 강성을 계산하였으며, 이는 실험결과와 잘 일치하는 것으로 나타났다. The purpose of this study was to examine the flexural behavior of reinforced concrete beams strengthened with CFRP strips. A total of 12 rectangular beams were tested. Test variables in this study were the shapes, bonded length and the number of longitudinal layers of CFRP strips. From the experimental study, flexural capacity of the beams strengthened with CFRP strips significantly increased compared to the reinforced concrete beam without a CFRP strip. Maximum increase of ultimate strength was found about 120% more than the control beam. In this test, most of the strengthened beams failed suddenly due to the debon ding of CFRP strips. It is also observed that the debonding of the strip was initiated in the flexural zone of the beam and propagated rapidly to the end of the beam. The ultimate tensile strains of CFRP strips in this test were occurred at the level of 36% of rupture tensile strength of the CFRP strip, and an analytical approach to compute the flexural strength of reinforced beams strengthened with CFRP strips based on the effective stresses was conducted..

백금 도금된 탄소반죽 전극을 이용한 일회용 글루코오스 센서

이동주,유재현,최강,최문희,김문환,류준오,한상현,차근식,남학현,Lee Dong Joo,Yoo Jae Hyun,Cui Gang,Choi Moon Hee,Kim Moon Hwan,Ryu Joon Oh,Han Sang-Hyun,Cha Geun Sig,Nam Hakhyun 한국전기화학회 1999 한국전기화학회지 Vol.2 No.4

Carbon paste전극을 백금도금 한 후 이 전극을 사용한 일회용 전류법 glucose센서를 제작하였다. 전극에 시료용액을 가한 후, voltammetry을 이용하여 본 센서의 감응성을 연구하였다. screen printing된 carbon paste전극 표면 위에 전기도금 방법으로 도입된 백금은 센서의 분석성능과 mediator의 전기 화학적 가역성을 크게 향상시켜 준다. 제작된 센서가 $[Fe(CN)_6]^{4-/3-}$에 대한 heterogeneous rate constant는 $1.45\times10^{-2}cm{\cdot}s^{-1}$이며, 이 센서는 적용전위 0.3V vs. Ag/AgCl에서 glucose에 대한 좋은 감응성을 보여주었다. 이 때 glucose에 대한 Michaelis-Menten상수는 24.5mM이다. 일회용 glucose 스트립 센서의 분석성능을 평가하기 위하여 NOVA S.P. Ultra M analyzer와 비교실험을 수행하였다. 이 때 시료용액으로서 $80\~297 mg/dL$ 범위의 glucose를 함유하고 있는 30여 종류의 혈청을 사용하였고, 상관계수는 0.983으로서 정밀도와 정확도가 비교적 우수함을 보여주었다. Disposable, amperometric glucose sensor was constructed using platinised carbon paste electrode. The sensor response was studied by amperometry and cyclic voltammetry applying sample solutions on the strip-type electrode. Platinization of screen-printed carbon paste electrode effectively improved the electrochemical reversibility of a mediator and the analytical characteristics of the sensor. The heterogeneous rate constant for $[Fe(CN)_6]^{4-/3-}$ was $1.45\times10^{-2}cm{\cdot}s^{-1}$. An applied potential of 0.3V vs. Ag/AgCl resulted in the best selectivity for glucose. The apparent Michaelis-Menten constant for glucose on the strip sensor, $K_m^{app}$, was 24.5 mM. To evaluate the analytical performance of the glucose sensor strip, a correlation study was performed with the NOVA S.P, Ultra M analyzer for 30 serum samples containing $80\~297mg/dL$ of glucose: the correlation coefficient value was 0.983. It can be seen that the strip sensor has satisfactory precision and accuracy.

Disposable Strip-Type Biosensors for Amperometric Determination of Galactose

Gwon, Kihak,Lee, Seonhwa,Nam, Hakhyun,Shin, Jae Ho The Korean Electrochemical Society 2020 Journal of electrochemical science and technology Vol.11 No.3

A development of disposable strip-type galactose sensor for point-of-care testing (POCT) was studied, which was constructed using screen-printed carbon electrodes. Galactose levels were determined by the redox reaction of galactose oxidase in the presence of potassium ferricyanide as an electron transfer mediator in a small sample volume (i.e., less than 1 µL). The optimal performance of biosensor was systematically designated by varying applied potential, operating pH, mediator concentration, and amount of enzyme on the electrode. The sensor system was identified as a highly active for the galactose measurement in terms of the sensitivity (slope = 4.76 ± 0.05 nA/µM) with high sensor-to-sensor reproducibility, the linearity (R² = 0.9915 in galactose concentration range from 0 to 400 µM), and response time (t_95% = <17 s). A lower applied potential (i.e., 0.25 V vs. Ag/AgCl) allowed to minimize interference from readily oxidizable metabolites such as ascorbic acid, acetaminophen, uric acid, and acetoacetic acid. The proposed galactose sensor represents a promising system with advantage for use in POCT.

Study on Tourism Carbon Emissions and Distribution Efficiency of Tourism Economics

Xiaoyu Cheng,Keshen Jiang 한국유통과학회 2018 Asian Journal of Business Environment (AJBE) Vol.8 No.2

Purpose - It is important to figure out the relationship between tourism carbon emissions and tourism economics for a healthy tourism development. Research design, data, and methodology - Data of this study are collected from 27 provinces (cities) of China. Tourist consumption stripping coefficient is used to calculate tourism carbon emissions. SBM-Undesirable model is used to measure the efficiency of tourism economics under the constraint of tourism carbon emissions. Results - The results show that: during the year of 2005-2015, there are obvious differences in totals and intensities of tourism carbon emissions among 27 provinces and cities which can be divided into three areas. There is a high possibility of underestimating the actual efficiency of tourism economics by leaving tourism carbon emissions out of account, and a high inefficiency caused by tourism carbon emissions will lead a low efficiency of tourism economics. Conclusions - The development of tourism should give consideration to both economic and environmental benefits, and reduce the inefficiency caused by tourism carbon emissions to improve efficiency of tourism economics by improving the level of technical efficiency and promoting technological progress.

Detection of Trace Copper Metal at Carbon Nanotube Based Electrodes Using Squarewave Anodic Stripping Voltammetry

Changkun Choi,정영삼,권용재 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.3

We investigate sensitivity and limit of detection (LOD) of trace copper (Cu) metal using pristine carbon nanotube (CNT) and acidified CNT (ACNT) electrodes. Squarewave based anodic stripping voltammetry (SWASV) is used to determine the stripped Cu concentration. Prior to performing the SWASV measurements, its optimal conditions are determined and with that, effects of potential scan rate and Cu2+ concentration on stripping current are evaluated. The measurements indicate that (1) ACNT electrode shows better results than CNT electrode and (2) stripping is controlled by surface reaction. In the given Cu2+ concentration range of 25- 150 ppb, peak stripping current has linearity with Cu2+ concentration. Quantitatively, sensitivity and LOD of Cu in ACNT electrode are 9.36 μA μM−1 and 3 ppb, while their values are 3.99 μA μM−1 and 3 ppb with CNT electrode. We evaluate the effect of three different water solutions (deionized water, tap water and river water) on stripping current and the confirm types of water don’t affect the sensitivity of Cu. It turns out by optical inspection and cyclic voltammetry that superiority of ACNT electrode to CNT electrode is attributed to exfoliation of CNT bundles and improved interfacial adhesion occurring during oxidation of CNTs.

Detection of Trace Copper Metal at Carbon Nanotube Based Electrodes Using Squarewave Anodic Stripping Voltammetry

Choi, Changkun,Jeong, Youngsam,Kwon, Yongchai Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3

We investigate sensitivity and limit of detection (LOD) of trace copper (Cu) metal using pristine carbon nanotube (CNT) and acidified CNT (ACNT) electrodes. Squarewave based anodic stripping voltammetry (SWASV) is used to determine the stripped Cu concentration. Prior to performing the SWASV measurements, its optimal conditions are determined and with that, effects of potential scan rate and $Cu^{2+}$ concentration on stripping current are evaluated. The measurements indicate that (1) ACNT electrode shows better results than CNT electrode and (2) stripping is controlled by surface reaction. In the given $Cu^{2+}$ concentration range of 25-150 ppb, peak stripping current has linearity with $Cu^{2+}$ concentration. Quantitatively, sensitivity and LOD of Cu in ACNT electrode are 9.36 ${\mu}A\;{\mu}M^{-1}$ and 3 ppb, while their values are 3.99 ${\mu}A\;{\mu}M^{-1}$ and 3 ppb with CNT electrode. We evaluate the effect of three different water solutions (deionized water, tap water and river water) on stripping current and the confirm types of water don't affect the sensitivity of Cu. It turns out by optical inspection and cyclic voltammetry that superiority of ACNT electrode to CNT electrode is attributed to exfoliation of CNT bundles and improved interfacial adhesion occurring during oxidation of CNTs.

Optimization of CO₂ stripping systems for removing inorganic carbons from anaerobic digestate of food waste

강진영,남지현,김영오,장하영,장덕진 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

The CO₂ stripping could be used to remove inorganic carbon species and alkalinity in wastewater with a high carbonate contents. The aim of the present work was to optimize the performance of two CO₂ stripping systems, so diffused and packed tower aerator. Experiments were conducted using anaerobic digestate of food waste in different agitation speed (0-500 rpm), temperature (25-65℃) and air flow rate (0-50 vvm). The results showed that the packed tower stripper was more efficient than diffused aerator. Most 80% of dissolved CO₂ was successfully removed at the conditions of 65℃, recirculation ratio of 10, packing volume of 60% and gas/liquid ratio of 20 in the continuous packed tower stripper. This study was supported by grants from COWEB. (Project No. 2013001580002)

Structural behavior of steel beams strengthened with CFRP strips and cables

Donghwan Lim 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.3

In the present study, structural behavior of steel beams strengthened with CFRP strips and cables was investigated by a series of experiments. For this purpose, two groups of experimental studies were carried out: one for the beam series strengthened only with CFRP strips and the other for the steel beam series strengthened with CFRP strips and prestressed wires. From this test, it is found that the flexural stiffness and strength of the steel beams strengthened with CFRP strips and cables were significantly improved comparing to the un-strengthened one. Three failure modes such as sudden de-bonding, splitting and rupturing of CFRP strips were observed. The ultimate tensile strains of attached CFRP strips on the steel beams were noticed in the range between 8,000με and 11,000με, and this result disclose the perfect composite reaction CFRP strips and steel beams.

초임계이산화탄소 내에서 공용매 및 초음파를 이용한 고농도이온주입 포토레지스트의 제거

김승호(Seung Ho Kim),임권택(Kwon Taek Lim) 한국청정기술학회 2009 청정기술 Vol.15 No.2

초임계이산화탄소와공용매의 혼합물을 사용하여 반도체 웨이퍼 기판으로부터 고농도이온주입 포토레지스트(HDIPR)를 제거하였다. 또한 고압 셀 내부에 초음파 장치를 부착하여 웨이펴 표면에 물리적 힘을 제공함으로서 세정용액의 HDIPR에 대한 스트리핑 성능을 현저히 향상시키고, 제거 시간을 단축시켰다. 공용매의 종류 및 농도, 공정 온도, 압력 변화에 따른 HDIPR 스트리핑 특성을 조사하였으며, 웨이퍼 표면의 제거 전후의 상태 및 성분을 scanning electron microscopy 과 energy dispersive X-ray spectrometer를 이용하여 분석하였다 10 w/w% 함량의 아세톤 공용매를 이용하여 공정압력 27.6 ㎫과 온도 343 K 의 조건에서 3분의 초음파 처리시간을 거쳐 HDIPR을 완전히 제거할 수 있었다. A high-dose ion-implanted photoresist (HDIPR) was stripped off from the surface of a semiconductor wafer by using a mixture of supercritical carbon dioxide and a co-solvent. The additional ultrasonication improved the stripping efficiency remarkably and thus reduced the stripping time by supplying physical force to the substrate. We investigated the effect of co-solvents, co-solvent concentration, and stripping temperature and pressure on the stripping efficiency. The wafer surfaces before and after stripping were analyzed by scanning electron microscopy and by an energy dispersive X-ray spectrometer. The HDIPR could be stripped off completely in 3 min with 10%(w/w) acetone/scCO₂ mixture at 27.6 ㎫ and 343 K.

탄소저감형 그린네트워크 도로 조성을 위한 중앙분리대 녹화유형 선호도 및 중요도 분석

정태열 ( Jung Tae-yeol ),박금미 ( Park Kum-mi ) 한국경관학회 2020 한국경관학회지 Vol.12 No.2

본 연구는 우리나라의 친환경 도로 공간 및 주변의 경관을 고려한 탄소저감형 그린네트워크 도로 조성을 위해 최적의 중앙분리대 녹화유형에 대한 선호도와 중요도 분석을 실시하였다. 이에 본 연구의 내용을 요약하면 다음과 같다. 첫째, 탄소저감형 그린네트워크 도로 중앙분리대 폭원은 3.0m 녹화형태는 교목을 가장 선호하고 그 다음은 소교목, 관목 순으로 나타났다. 둘째, 탄소저감형 그린네트워크 도로 중앙분리대 폭원별 녹화유형은 폭원 2.0m는 잔디+관목, 2.5m는 잔디+소관목+관목, 3.0m는 잔디+소관목+소교목, 그리고 3.5m의 경우 잔디+관목+교목을 선호하는 것으로 나타났다. 셋째, 탄소저감형 그린네트워크 도로 녹화유형 평가지표 중요도 분석 결과, 폭원 2.0m, 2.5m 경우 단순한 녹화유형 일수록 경제성 지표가 높게 나타났으며, 다양한 녹화유형 일수록 경관성과 환경성 지표가 높게 나타났다. 폭원 3.0m, 3.5m 경우 단순한 녹화유형 일수록 시공 및 유지 관리성 지표가 높게 나타났으며, 다양한 녹화유형 일수록 경관성과 환경성의 지표가 높게 나타났다. This study aims to find the optimum median strip greening types for the creation of low-carbon green network roads that take into account the environment-friendly road spaces and surrounding landscape. The findings of this study can be summarized as follows: First, it was found that as for the width of median strip for low-carbon green network roads, 3.0m was most preferred, and as for greening type, shrubs were most preferred, followed by small shrubs and trees. Second, as for greening types according to the width of median strips for low-carbon green network roads, it was found that in the case of the width of 2.0m, lawn + small shrub + tree was preferred, in the case of 2.5m, lawn + small shrub + shrub, in the case of 3.0m, lawn + small shrub + small tree, and in the case of 3.5m, lawn + shrub + tree, respectively. Third, as a result of analyzing the importance of evaluation indicators for the greening types of low-carbon green network roads, in the case of the width of 2.0 m and 2.5 m, the indicator of economic efficiency was found to be high among simpler greening types, and the indicators of landscape characteristics and environmental performance were found to be high among more diversified greening types. In the case of the width of 3.0m and 3.5m, the indicator of construction and maintainability was found to be high among simpler greening types, and the indicators of landscape characteristics and environmental performance were found to be high among more diversified greening types.