• 펄프종이기술
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• 제35권3호
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• pp.79-84
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• 2003

Oriental painting paper (Hwaseonji) was prepared from various kinds of plant fibers and its physical properties were investigated. The fibers used were classified into three different length of fibers; long fiber (<1.8 mm), medium fiber (1.4-1.8 mm) and short fiber (>1.4 mm). The fibers were mixed in the ratio of 15% long fiber, 25% medium fiber and 60% short fiber. The Hwaseonji prepared from mixing of the bamboo or rice straw pulp as a short fiber with the long and medium fibers showed excellent physical properties with a high smoothness and uniformity of Chinese ink blot. Mixing with LBKP as a short fiber was resulted in low physical properties, smoothness and wide ink blot. The properties of Hwaseonji, such as ink absorption, roughness and smoothness, may be predicted from the correlation of density with Chinese ink blot and smoothness.

• Journal of the Optical Society of Korea
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• 제7권2호
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• pp.89-96
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• 2003

A new method to control the free spectral range of a long period fiber grating is proposed and theoretically analyzed. As the refractive index decreases radially outward in the silica cladding due to graded doping of fluorine, waveguide dispersion in the cladding modes was modified to result in the effective indices change and subsequently the phase matching conditions for coupling with the core mode in a long period fiber grating. Enlargement of the free spectral range in a long period fiber grating was theoretically confirmed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.199-204
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• 1998

In this study, a method is presented which can be used to measure the fiber orientation distribution for thickness direction during injection molding using image processing. The intensity method in used for measuring the distribution. And the effects of fiber content, injection molding condictions on the orientation function are also discussed.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.373-379
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• 2006

Fiber characteristics and fiber distribution of thermomechanical pulp(TMP), bisulfite chemithermomechanical pulp(bisulfite CTMP), neutral sulfite chemithermomechanical pulp(neutral sulfite CTMP) from kenaf(Hibiscus cannabinus L., Malvaceae) cultivar Tainug-2 cultivated in the reclaimed land of Korea were examined to use effectively nonwood fibers as an alternative raw material sources for papermaking. Yields of TMP and CTMP from kenaf were lower than those of TMP from hardwoods and CTMP from softwoods and hardwoods. Bark fibers of kenaf cultivar Tainung-2 ranged 2.04 to 2.30 mm long and $18.7{\sim}19.7{\mu}m$ width. Core fibers averaged 0.63 to 0.80 mm long and $29.5{\sim}31.4{\mu}m$ wide. Coarseness of bark fiber was higher than that of core fiber, and fiber from TMP were higher than those from both bisulfite CTMP and neutral sulfite CTMP. Curl indexes of bark fibers were higher than those of core fibers. However curl indexes were not significantly affected by the pulping conditions. Short fiber distributions were higher in core fibers from TMP and CTMP and long fiber distributions were higher in bark fibers. There was no significant difference in fiber distribution of whole and core fibers obtained from TMP and CTMP, Fibers from neutral sulfite CTMP, however, exhibited a little higher long fiber distribution. Distinct difference in anatomical characteristics was found between core and bast fibers of kenaf plant. Parenchyma cell, pith parenchyma cell and vessel were observed in core fibers and bast fiber in bast sections.

• Journal of the Optical Society of Korea
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• 제3권2호
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• pp.74-79
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• 1999

We present a simple design rule for a passive temperature-compensating optical package. We also present experimentally that a package fabricated by using the design rule compensates the temperature dependence of the resonant wavelength of an optical long period fiber grating by varying the strain inside the fiber, The package fabricated in this work consists of two pieced of brass tube, 10 mm long, and a piece of nylon rod, 45.4 mm long. It is shown that the package can compensate the temperature-induce wavelength shifts of the long period grating to a range of 6.8 pm/$^{\circ}C$, compared with 0..48 nm/$^{\circ}C$ for an uncompensated grating. The reduced strength of the fiber caused by exposure to ultraviolet limits the performance of the package to the range operating temperature form -3 $^{\circ}C$ to 7$0^{\circ}C$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.876-879
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• 2004

The buried fiber optic cable as a distributed intrusion sensor for detecting and locating intruders along the long perimeters is proposed. Phase changes resulting from either the pressure of the intruder on the ground immediately above the buried fiber or from seismic disturbances in the vicinity are sensed by a phase-sensitive optical time-domain reflectometer. Light pulses from a Er:fiber cw laser with a narrow, <3kHz-range, spectral width and a frequency drift of < 1 MHz/min are injected into one end of the fiber, and the backscattered light from the fiber is monitored with a photodetector. Results of preliminary studies, measurement of phase changes produced by pressure and seismic disturbances in buried fiber optic cables and simulation of ${\varphi}-OTDR$ response over long fiber paths, to establish the feasibility of the concept are described. The field experiments indicate adequate phase changes, more than 1t-rad, are produced by intruders on foot and vehicle for burial depths in the 0.2 m to 1 m range in sand, clay and fine gravel soils. The simulations predict a range of 10 km with 35 m range resolution and 30 km with 90 m range resolution. This technology could in a cost-effective manner provide enhanced perimeter security.

• 대한기계학회논문집
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• 제14권2호
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• pp.393-398
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• 1990

A method is proposed which can be used to obtain the fibesr content distribution of compression molded long fiber-reinforced thermoplastic sheet for nonisothermal state. The fiber is modelled to be a sphere. Once the one-dimensional unsteady state heat conduction equation in solved, the mean temperature in defined across the thickness direction. The viscosity of matrix is determined with the mean temperature. Using the obtained viscosity, two-dimensional sheet0like part compression molding is simulated with the finite element method. Comparison with experiments shows that the method accurately predicts the distribution.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.761-767
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• 2007

We have developed novel optical-fiber sensors based on strain-induced long-period fiber gratings for monitoring the deformation of a hull. They have no external pressure for sustaining the mechanical formed gratings. The pressure, which provides a force to form the periodic grating along the single mode fiber, was realized by the bonding strength of a photopolymer. To reduce the polarization dependency of the sensors caused by the asymmetry structure of gratings, a Faraday Rotator Mirror (FRM) was utilized in this experiment. We have realized the polarization-insensitive function of the proposed sensors. The change of an external strain are measured by an optical spectrum analyzer. When the external stain increases. the attenuation at the resonant wavelength decreases and the loss peak was slightly shifted to the shorter wavelength.

• Journal of Advanced Marine Engineering and Technology
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• 제30권3호
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• pp.449-454
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• 2006

We present a pressure sensor based on the mechanically induced long-period fiber gratings (LPFG) for detecting the multi-location strain variation. The theoretical analysis is performed using a graphic method for a weakly guiding step-index fiber. The calculated results are in good agreement with the experimental results. In this study, from the fact that the optical parameters of a single-mode fiber slightly differ from manufacturing company to manufacturing company, the multipoint pressure-detection sensor systems composed two identical LPFGs are realized. When the pressure is applied two LPFG sensors at once, the resonance peaks are separated as much as about 40 nm. These types of sensor systems are well suited as a multipoint monitoring of strain or temperature in the ship or the smart structure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.201-204
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• 1999

Polarization mode dispersion (PMD) restrict the bend-width of single mode optical filer, and it is important parameter in the optical fiber having long-length. Although fiber has perfect circular symmetry, fiber bending, twisting and laws governing manufacture cause additional Polarization mode dispersion. The effect of polarization mode dispersion in general single mode fiber of long length is discussed in this paper. Measurement of PMD with random mode coupling were conducted in two kind of fibers using different laws governing manufacture and interferometric method.