본 연구에서는 각기 다른 두 제조사의 AgNW를 활용하여 스핀코팅 속도, 열처리 온도 및 방법 그리고 PDMS코팅 속도에 따른 AgNW/PDMS composite공정 연구를 실시하였다. 실험결과 peel off 특성에 영향을 미치는 인자로 건조방식이 주요하게 작용하며 공정온도 또한 전극 특성에 영향을 주었다. 핫플레이트를 사용한 건조방식은 한방향 열전달로 인해 PDMS를 충분히 건조시키지 못하였지만 오븐 건조를 통해 그 결점을 보완할 수 있었다. 또한, PDMS 코팅속도가 증가함에 따라 스트레처블 특성이 향상되었고 GF는 0.03에서 0.07로 약 100정도 향상되었다.

We present an excellent detection for nitrogen monoxide (NO) gas using polycrystalline ZnO wire-like films synthesized via a simple method combined with sputtering of Zn metallic films and subsequent thermal oxidation of the sputtered Zn nanowire films in dry air. Structural and morphological characterization revealed that it would be possible to synthesize polycrystalline hexagonal wurtzite ZnO films of a wire-like nanostructure with widths of 100-150 nm and lengths of several microns by controlling the sputtering conditions. It was found from the gas sensing measurements that the ZnO wirelike thin film gas sensor showed a significantly high response, with a maximum value of 29.2 for 2 ppm NO at 200 oC, as well as a reversible fast response to NO with a very low detection limit of 50 ppb. In addition, the ZnO wire-like thin film gas sensor also displayed an NO-selective sensing response for NO, O2, H2, NH3, and CO gases. Our results illustrate that polycrystalline ZnO wire-like thin films are potential sensing materials for the fabrication of NO-sensitive high-performance gas sensors.

This paper presents a protection method with FBG sensor in a 7-wire steel strand for improving measurement range of the sensor. For this purpose, both polyimide tube and teflon tube are employed to protect the FBG sensor. Uniaxial tests are carried out to compare their performances with those without the protection. The comparison showed that (1) maximum measurable deformation strain of the FBG-encapsulated strand with the polyimide tube enhancement is superior to the strand without the protection, (2) and it can measure effective strain larger than 1.00% without slip around the FBG sensor while there may occur the slip in the strand with teflon tube.

In this study, long term monitoring of tensile force of pre-tensioned prestressing strand embedded in UHPC ribbed deck by means of FBG sensor encapsulated into 7-wire prestressing strand. Based on the monitoring result for two years, it was confirmed that the technique proposed in this study offers efficient and robust way of monitoring the internal prestress of pre-tensioned PSC structures.

The FBG sensor responses simultaneously to changes in thermal strain as well as elastic strain. Thus the total strain measured from a single FBG sensor shall be corrected to obtain the elastic strain by removing the temperature effect. This paper addresses how the temperature effect can be removed when the FBG sensor is encapsulated in a 7-wire steel strand. For this purpose, fundamental properties of the FBG sensor are identified through tests using a controlled temperature chamber. Then field measurements on a UHPC pi girder with the size of 11.0 m long, 5.0 m wide, and 0.6 m high have been conducted for about one year, and the prestressing force is estimated using the raw data from the FBG sensor and by applying temperature correction technique proposed in this study. Estimated results indicate that the proposed correction technique is executable for extracting the elastic strain from monitoring data using the FBG sensor in civil infrastructures.