• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.161-166
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• 2006

A new fiber orientation sensor has been developed and tested on an actual paper machine to demonstrate its capability to function as a real-time monitoring system. First, we demonstrate the ability of the sensor system to detect the change in the fiber orientation angle while the sensor head, and not the paper, was intentionally rotated from $-90^{\circ}\;to\;+70^{\circ}$ with respect to the paper-traveling direction. Next, we demonstrate that this system can successfully detect the change in the magnitude and angle of fiber orientation in running paper when the direction of material flow on the wire was changed on the paper machine. The angle and magnitude of fiber orientation were independently confirmed by SST and MOA measurements. Furthermore, we found that the system was capable of measuring the basis weight and the moisture content of running paper while detecting the angle and magnitude of fiber orientation.

• 전자공학회논문지A
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• 제33A권5호
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• pp.142-148
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• 1996

It is shown that a simple vector analysis method can provide beam cone shapes for laser bemas non-paraxially input to dielectric boundaries with inclination. Acceptance coen shapes for angled-endface fibers are calculated by the method. Beam cone shapes inside InP substrates are also calculated by the method for the coupling of an optical fiber and an InP-based photodiode using a Si v-groove. The effectiveness and errors of the recently suggested matrix method for inclined boundaries are also studied.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.423.1-423.1
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• 2016

Polyvinylidene fluoride (PVDF) has drawn much attention due to its many advantages. PVDF shows high mechanical strength and flexibility, thermal stability, and good piezoelectricity enabling its application to various fields such as sensors, actuators, and energy transducers. Further studies have been conducted on PVDF in the form of thin films. The thin films exhibit different ionic conductivity according to the number of pores within the film, letting these films to be applied as electrolytes or separators of batteries. Porous PVDF membranes are also easily processed, usually made by using electrospinning. However, a large portion of researches were conducted using PVDF membranes produced by far field electrospinning, which is not a well-controlled experimental method. In this paper, we use near field electrospinning (NFES) process for more controlled, small-scaled, mesh type PVDF structures of nano to micro fibers fabricated by controlling process parameters and investigate the properties of such membranous structures. These membranes vary according to geometrical shape, pore density, and fiber thickness. We then measured the mechanical strength and piezoelectric characteristic of the structures. With various geometries in the fiber structures and various scales in the fibers, these types of structures can potentially lead to broader applications for stretchable electronics and dielectric electro active polymers.

• Applied Microscopy
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• 제47권1호
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• pp.55-62
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• 2017

This paper describes experiments aimed at characterizing the behavior of field electron emitters fabricated by coating carbon fibers with epoxylite resin. Polyacrylonitrile carbon fibers of type VPR-19, thermally treated at $2,800^{\circ}C$, were used. Each was initially prepared in a "uncoated" state, by standard electro polishing and cleaning techniques, and was then examined in a scanning electron microscope. The fiber was then baked overnight in a field electron microscope (FEM) vacuum chamber. Current-voltage characteristics and FEM images were recorded on the following day or later. The fiber was then removed from the FEM, coated with resin, "cured" by baking, and replaced in the FEM. After another overnight bake, the FEM characterization measurements were repeated. The coated fibers had significantly better performance than uncoated fibers. This confirms the results of earlier experiments, and is thought to be due in part to the formation of a conducting channel in the resin over layer. For the coated fiber, lower voltages were needed to obtain the same emission current. The coated fibers have current-voltage characteristics that show smoother trends, with greater stability and repeatability. No switch-on phenomena were observed. In addition, the emission images on the phosphor-coated FEM screen were more concentrated, and hence brighter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.216-219
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• 1995

One of the principal problems encountered in the use of glass fiber reinforced Plastic composites(GFRP) is to establish an active fiber surface to achieve maximum adhesion between resin and fiber surface. In order to develope new process to overcome the disadvantage of chemical agent, we have studied the effect of reactive plasma glass surface treatment on the electrical and mechanical properties of glass fiber reinforced epoxy composites. It is found that the electrical and mechanical characteristics of the composites treated with plasma is improved especially in the dielectric strength by 20% and tensile strength by 15%, whereas the tan $\delta$ is decreased significantly.

• 센서학회지
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• 제7권1호
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• pp.39-44
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• 1998

연속적인 단일모드 광섬유에 설치 가능한 저반사율을 가진 광섬유 거울들이 기계식 접합기와 깨끗이 절단된 끝단면에 $TiO_{2}$ 유전체 물질로 코팅된 광섬유 단편들을 사용하여 만들어 졌다. 0.1%의 반사율을 가진 광섬유 거울들이 만들어 졌을 때 광섬유 거울의 삽입손실의 범위는 0.055dB 부터 0.3dB 였으며 평균 삽입손실은 0.15dB였다. 저반사율을 가진 광섬유 거울들은 필드에서 쉽게 만들어 질 수 있었다.

• Advances in nano research
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• 제1권4호
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• pp.183-192
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• 2013

One-dimensional multiferroic nanostructured composites have drawn increasing interest as they show tremendous potential for multifunctional devices and applications. Herein, we report the synthesis, structural and dielectric characterization of barium titanate ($BaTiO_3$)-bismuth ferrite ($BiFeO_3$) composite fibers that were obtained using a novel sol-gel based electrospinning technique. The microstructure of the fibers was investigated using scanning electron microscopy and transmission electron microscopy. The fibers had an average diameter of 120 nm and were composed of nanoparticles. X-ray diffraction (XRD) study of the composite fibers demonstrated that the fibers are composed of perovskite cubic $BaTiO_3$-$BiFeO_3$ crystallites. The magnetic hysteresis loops of the resultant fibers demonstrated that the fibers were ferromagnetic with magnetic coercivity of 1500 Oe and saturation magnetization of 1.55 emu/g at room temperature (300 K). Additionally, the dielectric response of the composite fibers was characterized as a function of frequency. Their dielectric permittivity was found to be 140 and their dielectric loss was low in the frequency range from 1000 Hz to $10^7$ Hz.

• 한국초전도ㆍ저온공학회논문지
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• 제13권3호
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• pp.5-9
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• 2011

DC high-temperature superconducting(HTS) cable system has attracted a great deal of interest from the view point of low loss, dense structure and large capacity. A HTS cable system is made of cable and termination. The insulating materials and insulation technology must be solved for the long life, reliability and compact of cable system. In this paper, we will report on the dielectric breakdown characteristics of insulating materials for HTS cable and termination. The AC, DC and lightning impulse breakdown strength of laminated polypropylene paper(PPLP) and glass fiber reinforced plastic(GFRP) have been measured under nitrogen pressures in the range of 0.l-0.4MPa. PPLP and GFRP are found to have a significantly higher DC breakdown strength. Also, DC surface flashover voltage of negative polarity is slightly higher than that of positive polarity in GFRP.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.797-803
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• 2001

The on-line cure monitoring of fiber reinforced thermosetting resin matrix composite material was performed for the better quality and productivity during manufacturing. Since the dissipation factor measured by dielectrometry method is dependent on the degree of cure and temperature of resin, in this study, a new method to obtain the degree of cure during on-line cure monitoring for glass/polyester composites was developed by employing a combination function of the temperature and the dissipation factor. Two sensor signals from a K-type thermocouple and an interdigitated dielectric sensor were processed during curing process under various cure cycles. The DSC (Differential Scanning Calorimetry) data was also used for the reference of degree of cure.

• 대한기계학회논문집
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• 제19권7호
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• pp.1563-1572
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• 1995

The on-line cure monitoring during the cure process of fiber reinforced resin matrix composite material is important for the better quality and productivity. Among several cure monitoring methods, the dielectrometry that uses electrodes as its sensor is known to be the most promising method. In this study, the sensitivity of the dielectric sensor for the on-line cure monitoring was analyzed by finite element method and compared to the experimental results. Using the analytical results, the equation for the capacitance of the sensor was derived. Also, the optimal sensor design method was suggested after analyzing several different sensor shapes.