• Journal of the Optical Society of Korea
• /
• 제19권4호
• /
• pp.327-333
• /
• 2015

This paper reports the fabrication of various micro-lensed single-mode optical fibers through the use of an enhanced peak power $CO_2$ laser beam. The end faces of the optical fibers are exposed to the $CO_2$ laser beam to form convex, concave, and conical shape optical fiber tips. Peak power of the $CO_2$ laser beam was varied from 0.8 W to 1.5 W depending on the shape of the optical fiber tip. We also discover the dependence of the angle of the optical fiber tip on the rotation angle and the number of $CO_2$ laser irradiations. The angle shows an increasing trend with both these parameters. We achieve a wide range of lenticular fibers with end face angle varying from $4.47^{\circ}$ to $8.13^{\circ}$. Furthermore, we investigate the emission pattern of light from the developed micro-lensed fibers. The proposed $CO_2$ laser based optical fiber reshaping technique shows great consistency, and thus is suitable for commercial applications.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
• /
• pp.345-346
• /
• 2018

In this study, various materials such as epoxy material, urethane material, cement material, and acrylic material are used to solve the water leakage occurring in underground structures. However, in the reality that the durability is insufficient and the effect is insufficient, it is aimed to improve the repairing effect by using cement and acrylics n combination. As a first study, we tried to verify the performance of rapid micro cement and cement paste and to improve the performance by checking the product properties. Three types of micro cement are evaluated. Three types of micro cement are used: fiber inclusion, fiber unfolding, and cement paste. When the material is selected for micro cement, it is applied to the field to understand the maintenance effect and durability.

• Structural Engineering and Mechanics
• /
• 제82권3호
• /
• pp.295-312
• /
• 2022

This study investigates the effects of nano silica (NS) and micro steel fiber on the properties of ultra-high-performance concrete (UHPC). The experimental consists of three groups, each one with five percentages of NS content (0%, 2%, 4%, 6% and 8%) in addition to the 20% silica fume and 20% quartz powder proportioned according to the weight of cement added to the mixtures. In addition, three percentages of micro steel fibers (0%, 1% and 2%) were considered. Different mixtures with varying percentages of NS and micro steel fibers were prepared to set the water-to-binder ratio, such as 0.16% and 1.8% superplasticizer proportioned according the weight of the binder materials. The fresh properties, mechanical properties and elevated temperatures of the mixtures were calculated. Then, the results from the microstructure analyses were compared with that of the reference mixtureand it was found that 6% replacement of cement with NS was optimum replacement level. When the NS content was increased from 0% to 6%, the air content and permeability of the mixture decreased by 35% and 39%, the compressive and tensile strength improved by 21% and 18% and the flexural strength and modulus of elasticity increased by 20% and 11.5%, respectively. However, the effect of micro steel fibres on the compressive strength was inconclusive. The overall results indicate that micro steel fibres have the potential to improve the tensile strength, flexure strength and modulus of elasticity of the UHPC. The use of 6% NS together with 1% micro-steel fiber increased the concrete strength and reduce the cost of concrete mix.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.105-109
• /
• 2001

The micro optical parts such as ferrules are required to be manufactured within very small tolerances, as the slight deviation of the tolerance would give very large amount of loss in communication efficiency. For efficient optical communication, outer diameter, fiber diameter, fiber separation and eccentricity are significant parameters to be inspected., Thus we developed an automatic inspection system to evaluate shape parameters of the optical fiber connectors(ferrule) upto submicron accuracy using machine vision. new optical probe of multi fields of views has been developed and the image processing and data analysis algorithms have been complemented in real time basis. The developed system is successfully used in the practical ferrule manufacturing industry, and about 0.1$\mu\textrm{m}$ accuracy can be obtained with very fast inspection time.

• 한국기계기술학회지
• /
• 제13권4호
• /
• pp.93-99
• /
• 2011

This paper presents a new type of optical silicon accelerometer using deep reactive ion etching (DRIE) and micro-stereolithography technology. Optical silicon accelerometer is based on a mass suspended by four vertical beams. A vertical shutter at the end of the mass can only moves along the sensing axis in the optical path between two single-mode optical fibers. The shutter modulates intensity of light from a laser diode reaching a photo detector. With the DRIE technique for (100) silicon, it is possible to etch a vertical shutter and beam. This ensures low sensitivity to accelerations that are not along the sensing axis. The microstructure for sensor packaging and optical fiber fixing was fabricated using micro stereolithography technology. Designed sensors are two types and each resonant frequency is about 15 kHz and 5 kHz.

• 대한전자공학회논문지
• /
• 제18권3호
• /
• pp.21-24
• /
• 1981

Micro-torch를 사용하여 두 개와 taper를 동시에 제작하고, fusion splicing에 외해 광섬유 t-branch률 제작하였다. Y-branch의 insertion loss는 2.6dB, branching율은 0.98까지 얻을 수 있었다. 또 Y-branch를 OTDR의 제작에 응용하여 광학계를 대폭 간소화 하였으며, 길 이 측정오차 ±5m, 손실 측정오차 ±0.5bB/km로 광섬유의 특성을 측정할 수 있었다.

• 펄프종이기술
• /
• 제39권1호
• /
• pp.1-7
• /
• 2007

Internal fibrillation of pulp fiber is an important factor affecting paper properties. Internal fibrillation of pulp fiber is usually introduced with several kinds of modifications of fiber by the mechanical treatment such as refining, high shear and/or high consistency mixing, etc. Unfortunately there are no standardized methods that can characterize the extent of internal fibrillation and its contribution on the paper properties. The purpose of this study is to try and find the potential methods that can characterize the internal fibrillation of pulp fiber quantitatively. Softwood bleached kraft pulp was treated with Hobart mixer to introduce the internal fibrillation without the significant fiber damage and external fibrillation. The extent of internal fibrillation was increased with the increase of mechanical treatment consistency. Several fiber properties were measured to find the potential means that could characterize and quantity the internal fibrillation. Laminated area could not be used as a means for quantifying the internal fibrillation because of the effect of swelling and the different internal fibrillation behavior at different mechanical treatment consistency. Micro and macro internal fibrillation models were proposed for describing the different behavior for the mechanical treatment at low and high consistencies of pulp. The Internal fibrillation showed good correlation with swelling of fiber wall. This trend was confirmed through the measurement of wall thickness and/or cross section area of fiber. Therefore the internal fibrillation possibly can be described as the indices indicating the change of wall thickness and/or cross section area.

• 대한전자공학회논문지SD
• /
• 제41권7호
• /
• pp.13-20
• /
• 2004

미세 광학 벤치의 설계를 위해서 두 가지 테스트 벤치에 대해 결합효율을 계산하였다. 광섬유로 들어오고 나가게 되는 빛을 볼 렌즈를 통과한 것과 그렇지 않은 것으로 설계하였다. 미세 광학 벤치의 실제 제작 과정에서 발생할 수 있는 광소자들의 위치 에러를 고려하여 시뮬레이션을 하였고, 그것들의 허용오차를 -3 ㏈ 조건으로 정하였다. 볼 렌즈가 없는 fiber-to-fiber에서는 lateral misalignment가 2.7 um 그리고 tilt 에러가 5.8o 이내로 나타났다. 각각의 광섬유 앞단에 광의 집속을 위해 볼 렌즈가 놓여지면 working distance는 60 um로 확장되어지나, 각각의 광소자들이 놓여진 위치 파라미터 사이에 보다 강한 교호작용이 존재하기 때문에 tolerance design을 위해 교호작용을 함께 고려해야 한다.

• 센서학회지
• /
• 제17권3호
• /
• pp.162-167
• /
• 2008

In this paper we report on the electrical properties of carbon fiber which is an attractive material for strain gauges and can also be applied to resonating micro sensors. The carbon fibers used in this research was manufactured from polyactylonitrile (PAN). The fabricated carbon fibers had about $10\;{\mu}m$ in length and several centimeters in length. We employed a micro structure to measure electrical properties of the carbon fiber. The measured electrical resistivity of the carbon fibers were about $3{\times}10^{-3}{\Omega}{\cdot}cm$ A gauge factor of the carbon fiber is also observed with the same system and it was about 400, depending on the structure of the carbon fiber. For the sensor applications of the carbon fiber, it is selectively placed between the gap of Al electrodes using a dielectrophoresis method. When the carbon fiber is resonated by a piezoelectric ceramic, resistance change at a variety of resonance mode was observed through an electrical system.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.692-693
• /
• 2004

We introduce a new velocity sensor, micro-flown sensor, which was developed by H-E de Bree. The sound absorption coefficients of a fiber material with the conventional pressure microphones and the micro-flown sensors were measured and compared. The experimental results show that both sensors could be well applied to measure the sound absorption coefficient but the pressure sensor was rather stable than micro-flown sensor