• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.107-110
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• 2004

In this paper, a new structural health monitoring technique for composite laminates through the use of embedded fiber Bragg grating (FBG) sensors is presented. The method traces the ply stress states of a laminate and compares them with failure criteria during the service time of structures. The ply stress state of every ply composing the composite laminate can be obtained using classical lamination theory by embedded FBG sensors in the laminate. Graphite/epoxy laminate specimens, embedded with three FBG sensors, were fabricated. Tension tests were performed to evaluate the ply stress states tracing technique. Experimental results show that laminates experience fracture when the ply stress states are over the boundaries of failure criteria. In this method, critical damage can be detected by the ply stress states which are close to the boundaries of the failure criteria.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.145-148
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• 2006

Near surface mounted (NSM) is a recent strengthening technique based on bonding fiber reinforced polymer (CFRP) bars (rods and laminate strips), the use of NSM FRP bars is Emerging as a promising technology for increasing flexural strength of deficient concrete. In order for this technique to perform effectively, the structural behaviour of RC element strengthened with NSM FRP bars to be fully characterized. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam test were a diffrent type of strengthening length.

• 한국산업보건학회지
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• 제5권2호
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• pp.137-146
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• 1995

Twenty(20) large commercial buildings located in Seoul with friable sprayed-on surface insulation material on ceilings were investigated for asbestos content in bulk material by polarized light microscopy and for airborne fiber concentrations in buildings by phase contrast microscopy. In addition, such building-related variables as building age, numbers of traffic, airflow, surface conditions of the ceiling, temperature, and humidity were studied for any correlation with airborne fiber concentrations. The results were as follows: 1. Chrysotile asbestos was found in two bulk samples with 3-5% content and with <1%in one sample out of total 20 bulk samples collected. Glass fiber and mineral wool were the two major constituents of the bulk samples. 2. The ceiling surfaces were very friable in 16 buildings and were relatively hard in 4 buildings. The friability of the surface material was dependent upon the type and the amount of binder that had been mixed with the sprayed-on surface material. 3. Airborne fiber concentrations were log-normally distributed and the geometric mean(geometric standard deviation) fiber concentrations in the underground parking lots, inside buildings, and outdoor ambient air were 0.0063(1.97)f/cc, 0.0068(2.29)f/cc, and 0.0033(2.36)f/cc, respectively. 4. No significant relationship of airborne fiber concentrations and all building-related variables studied except humidity was found. The results of this study suggest that the sprayed-on surface insulation material found in some commercial buildings may possibly be contaminated with asbestos. Since most of the ceiling surfaces surveyed were very friable and poorly maintained and the airborne fiber concentrations were relatively high, there is a possibility of asbestos fiber contamination in these buildings, particularly at those buildings with asbestos-contaminated surface material. Since poorly maintained surface conditions were thought to be a source of high airborne fiber concentrations, there is a urgent need of a systematic operation and maintenance program. Further study of non-occupational asbestos exposure in general population utilizing advanced analytical technique such as transmission electron microscopy is highly recommended.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1994년도 추계 학술발표 강연 및 논문 개요집
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• pp.133-136
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• 1994

A microcechanical analysis based on the single fiber model has studied in the standpoint of stress-strain hysteresis response. A comparative study of constraint and unconstraint effects ha been taken into account to investigate includes the stress grouping technique to evaluate the domain-based field quantities. Results indicated that the development of significant fiber stresses both for the tensile and compressive loading, due to the constraint effects, provides an important contribution to the composited strengthening

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1278-1280
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• 1995

A probe type fiber-optic sensing techique for electric current measurement is applied in this paper. The technique is based on the Faraday effect which meaning is that polarization state of light is rotated by magnetic field. In experiment, test wire is located at inside and outside of the probe to be measured. The experimental results prove not only linear property, but also polarization rotation property according to the distance from outside of probe.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1249-1250
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• 2004

In this paper, we report new technique of preparation of material for flexible displays and E-paper technology. This material represents porous polymeric fiber based on polyacrylonitrile filled by liquid crystal.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 2000년도 춘계 학술논문발표회 논문집
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• pp.52-57
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• 2000

This paper discusses frequency analysis based on frequency spectrum in orthogonal cutting of fiber-matrix composite materials. A glass reinforced polyester (GFRP) was used as workpiece. Analysis method employs a force sensor and the signals from the sensor are processed using a fast Fourier transform (FFT) technique. The experimental correlation between the different chip formation mechanisms and model coefficients are then established. (omitted)

• 전자공학회논문지D
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• 제34D권4호
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• pp.94-99
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• 1997

A new method of stbilizing the sagnac interferometric fiber optic current sensor inteh presence of birefringences and phase is presented. This method is realized by dividing the output of the ac current signal with the modulation signal output. Using the technique the stability of the current sensor was improve dmore than 4.5 times at 800Arms for 2 hours. The current sensor also shows good linearity up to 100Arms.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1991년도 봄 학술발표회 논문집
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• pp.3-7
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• 1991

Considering the relatively large amount of stable flexural teat results available for steel fiber reinforced concrete (SFRC) and their dependency on the constitutive behavior of the material, a technique called “System Identification” is used for interpretating the flexural test data in order to obtain basic information on the tensile constitutive behavior of steel fiber reinforced concrete. “System Identification” was successful in obtaining optimum sets of parameters which provide satisfactory matches between the measured and predicted flexural load-deflection relationships.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.866-873
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• 2000

Reinforced concrete structure can be strengthened by glass fiber reinforced plastic thin panels. The GFRP-Thin Panels are manufactured by pressing form and their application technique are similar to steel plates. The use of FGRP-Thin Panels presents several advantages. The advantages of this structural system are the case of application, the elimination of joint and corrosion at the epoxy-panel interface. This paper introduces the method of manufacturing about GFRP-Thin Panels, mechanical properties and the application of reinforced concrete structures.