• Journal of the Korea Concrete Institute
• /
• v.12 no.3
• /
• pp.67-75
• /
• 2000

It was well recognized that the damages associated mainly with the aging of civil infrastructures were one of very serious problems for assurance of safety and reliability. Recently carbon fiber sheet(CFS) has been widely used for reinforcement and rehabilitation of damaged concrete beam. However, the fundamental mechanism of load transfer and its load-resistant for carbon fiber sheet reinforced concrete are not fully understood. In this study, three point bending test has been carried out to understand the damage progress and the micro-failure mechanism of CFS reinforced mortars. For this purpose, four different types of specimens are used, that is, mortar, steel bar reinforced mortar, CFS reinforced mortar, and steel bar and CFS reinforced morter. Acoustic Emission(AE) technique was used to evaluate the characteristics of damage progress and the failure mechanism of specimens. in addition, two-dimensional AE source location was also performed to monitor crack initiation and propagation processes for these specimens.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.53 no.1
• /
• pp.15-19
• /
• 2004

In this paper, we present the fabrication and characteristic analysis of Sagnac interferometric optical fiber senior(OFS) system for detecting pulsed ultrasonic signal in underwater. The hollow cylindrical mandrel wound round by single mode optical fiber is used as sensing component. The ultrasonic signal source is simulated by the PZT actuator operated by an function generator. The distance dependency of the OFS's sensitivity was measured. The sensitivity has been shown to be inversely propotional to the square-root of distance between ultrasonic source and sensing component. It has also been shown that the OFS could detect the signals less affected by ultrasonic path comparing to conventional acousto-electric sensor. and accurate location of ultrasonic signal could be carried out using two OFSs.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.2186-2188
• /
• 2000

A fiberoptic sensor using an SLD as a light source has been studied. The sensor system employs an intrinsic fiber Fabry-Perot interferometer as a sensing tip and a fiber Mach-Zehnder interferometer as a processing one. A free loading test for temperature application shows that the fiberoptic sensor has a wide-dynamic range as well as high resolution. Due to the inherent property of the optical fiber itself and the intrinsic Fabry-Perot interferometer. the fiberoptic sensor gives obvious benefits when it is applied to harsh environments to monitor some physical parameters such as temperature, strain, pressure and vibration.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.07a
• /
• pp.20-21
• /
• 2003

Erbium doped fiber (EDF) sources are useful devices for characterization of optical components for wavelength division multiplexing (WDM) fiber optic communication system. Therefore, there are many efforts to extend the bandwidth and to increase the power of the light source. Especially, L-band ASE source uses the low inversion state of EDF. It makes the power efficiency very low and needs a lot of fiber as several times as the fiber needed in C-band ASE generation. (omitted)

• Korean Journal of Optics and Photonics
• /
• v.14 no.4
• /
• pp.460-465
• /
• 2003

Characteristics of 0.98 $\mu$m-pumped erbium-doped fiber (EDF) sources with double-pass forward (DPF) configuration are analyzed by numerical calculation. Various source characteristics such as output power, spectral width and mean-wavelength stability are investigated with the variation of EDF length, pump power and pump wavelength. Some of the numerical results are compared with experimental ones for verification. The results show that the characteristics of sources with DPF configuration can change considerably with the EDF length. It is also found that an optimum design can exist for stable mean-wavelength against fluctuations of pump power and pump wavelength.

• Asian-Australasian Journal of Animal Sciences
• /
• v.14 no.10
• /
• pp.1374-1382
• /
• 2001

Fifteen Inner Mongolian wethers with permanent ruminal and duodenal cannulas were used to study the effects of dietary rumen-undegradable protein (RUP) to rumen-degradable protein (RDP) ratios or protein sources on fiber digestion in the gastrointestinal tract and ruminal fluid characteristics. Fiber digestion and ruminal fermentation were not affected (p>0.05) by dietary RUP to RDP ratios (from 1.54 to 0.72). Soybean meal supplementation improved ruminal digestion. Fish meal supplementation increased (p<0.05) the ruminal degradability of fiber. The different RUP to RDP ratios (from 1.54 to 0.72) did not influence (p>0.05) ruminal fluid pH, but there were differences (p<0.05) in ruminal fluid $NH_3-N$ concentration because of urea replacement. Soybean meal as a dietary protein source decreased (p<0.05) ruminal fluid pH and increased (p<0.05 or p<0.01) $NH_3-N$, acetate, propionate and butyrate concentrations in the rumen. Fish meal as a dietary protein source decreased (p<0.05 or p<0.01) ruminal $NH_3-N$ and acetate concentrations and increased (p<0.05) ruminal propionate concentration. It can be concluded that dietary protein sources have more significant effect on fiber digestion and ruminal fermentation than different dietary RUP to RDP ratios, when the dietary crude protein requirements of growing sheep are satisfied.

• Composites Research
• /
• v.29 no.5
• /
• pp.293-298
• /
• 2016

In this paper, Glass Fiber Reinforced Thermoplastic (GFRTP) for automotive headlight source module was fabricated by compounding and injection molding using PPS (Poly Phenylene Sulfide) resin with glass fiber which has three cross section (round type, cocoon type, flat type). Tensile, flexural, impact properties were investigated on effect of cross section, glass fiber contents. And it was observed flatness, dimensional stability, fluidity depending on glass fiber cross section. As a result, flat glass fiber reinforced thermoplastic's mechanical properties were most excellent. Also, dimensional stability and flatness showed better results when using flat glass fiber.

• Journal of Food Hygiene and Safety
• /
• v.7 no.4
• /
• pp.173-176
• /
• 1992

Non-absorbable substances in foods, for instance dietary fiber had been previously known as a non-nutritive part of foods. Recently , such a category has been gradually changed to as one of nutrients, As a main reason, dietary fibers includes many poly-or oligo-saccharides, which as resistant to alimentary hydrolyzing enzyme, However, parts of them are fermented by intestinal micro-organism to produce short chain fatty acids and so on. They are absorbed and utilized by human being. Now, it may be naturally accepted that dietary fiber is a kind of nutrients. Dietary fiber exerts many useful functions on body. They are classified into three large function , physicochemical function, physiological function and biological function. The last function of dietary fiber will be presented in the symphosium. Dietary fiber has several kinds of nutritional properties. One is energy source. Short chain fatty acids(SCFA) are oxidized and produced energy in body. Dietary fiber has not high energy, but not zero kilocalories. Another one is to be a constitutional component of higher animals' tissue. Last but most important one is physiological functions of dietary fiber.

• Journal of Sensor Science and Technology
• /
• v.14 no.4
• /
• pp.244-249
• /
• 2005

In this study, radiation sensor tips are fabricated for remote sensing of X or gamma ray with inorganic scintillators and plastic optical fiber. The visible range of light from the inorganic scintillator that is generated by radiation source is guided by the plastic optical fiber and is measured by optical detector and power-meter. Two kinds of sensor tips are designed and fabricated such as film type and powder type. Many kinds of inorganic scintillators are used to fabricate both sensor tips, and the different wavelength of emitting lights from them are measured to determine the optimal inorganic scintillator which has maximum light output. As a radiation source X-ray generator and Ir-192 are selected to test a performance of sensor tip. It is expected that the fiber-optic radiation sensor is widely used in nuclear industry and medical applications due to its special characteristics such as good flexibility, easy in processing, long lengths and no interference to electro magnetic field.

• Korean Journal of Optics and Photonics
• /
• v.16 no.6
• /
• pp.490-493
• /
• 2005

We have experimentally studied supercontinuum generation in a photonic crystal fiber as a function of pump wavelength and intensity with 100 fs pulsewidth. A supercontinuum over 750 nm spectral width with amplitude variation less than 10 dB has been achieved. It was generated by coupling femtosecond pulses from a mode-locked Ti:Sapphire laser into a 2 m long photonic crystal fiber. Adjusting the parameters of the pump source, it was also possible to control different spectral features of the supercontinuum radiation.