• Structural Engineering and Mechanics
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• 제27권3호
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• pp.347-363
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• 2007

Assessment of structural behaviour of corrosion affected structures is an important issue, which would help in making certain decisions pertaining to the inspection, repair, strengthening, replacement and demolition of such structures. The paper presents formulations to predict the loss of weight and the loss of cross-sectional area of the reinforcing bar undergoing corrosion based on the earlier study carried out by the present authors (Bhargava et al. 2006). These formulations have further been used to analytically evaluate the ultimate bending moment and ultimate shear force capacity of the corroded concrete beams. Results of the present study indicate that, a considerably good agreement has been observed between the experimental and the analytically predicted values for the weight loss and reduction in radius of the corroded reinforcing bars. A considerably good agreement has also been observed between the experimental and the analytically predicted values of ultimate bending moment and ultimate shear force capacity for the corroded concrete beams.

• 한국염색가공학회지
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• 제10권2호
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• pp.1-7
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• 1998

In this study, PET fabric was hydrolyzed with NaOH using the Tank m/c and Liquor-flow m/c to determine the alkali hydrolysis properties of PET fabrics. The results were as follows ： The weft density and tensile strength of PET fabrics hydrolyzed with Liquor-flow m/c were higher than those hydrolyzed with Tank m/c in case of less than 10％ of weight loss. However, above 10％ of weight loss, reverse phenomenon was showed. K/S value of hydrolyzed PET with Liquor-flow m/c was higher than that with Tank m/c above 10％ of weight loss. It was observed that the micropores of PET surface were collapsed due to physical force(abrasion and collision) during hydrolysis. Bending rigidity of hydrolyzed PET fabric was about 32％ and 40％ of bending rigidity of warp and weft direction of untreated fabric at 7％ of weight loss, respectively. Above 7％ of weight loss, decrease rate was decreased.

• Current Optics and Photonics
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• 제5권6호
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• pp.730-737
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• 2021

Transmission spectra are measured from waveguide-coupled ring resonators fabricated with SiN_x on SiO₂. By using ring resonators with various radii and several index contrasts, the behavior of the quality factors is investigated. As the index contrast decreases, the dominant loss is from scattering for a large resonator, while that changes from scattering loss to bending loss for a small resonator. We verify that the quality factor can be drastically improved by reducing the index contrast in large ring resonators.

• Journal of Advanced Research in Ocean Engineering
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• 제3권1호
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• pp.1-14
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• 2017

The safety analysis of an earthquake is carried out during the operation of a subsea pipeline and an onshore pipeline. Several cases are proposed for consideration. In the case of a buried pipeline, permanent ground deformation by the earthquake and an increase of internal pressure by the acceleration of the earthquake should be considered. In the case of a subsea pipeline, a bending moment is caused by liquefaction of the backfill material on a trenched seabed, etc., which results in a high bending moment of the buried pipeline. The bending moment causes the collapse of the subsea pipeline or a leak of crude oil or gas, which results in economic loss due to enormous environmental contamination and social economic loss owing to operation functional failure. Thus, in order to prevent economic loss and operation loss, structurally sensitive design with regard to seismic characteristics must be performed in the buried pipeline in advance, and the negative impact on the buried pipeline must be minimized by conducting a thorough analysis on the seabed and backfilling material selection. Moreover, it is proposed to consider the selection of material properties for the buried pipeline. A more economical review is also required for detailed study.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.105-110
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• 2006

The most sensitive part of the installed optical cable is the optical loss variation of the splicing point according to the environmental changes. This paper presents the details of the experimental results of the external environmental changes on optical loss, such as bending, temperature variation, temperature variation after water osmosis and variation. Through the bending test of optical fiber, rapid increase of optical loss was measured within the diameter of 30mm. The result of optical loss variation within the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$ is less than 0.02dB. It was confirmed that the maximum optical loss increased up to 0.2dB in case of water osmosis within the temperature range of $-40^{\circ}C{\sim}80^{\circ}C$. There is small optical loss variation of 0.01dB under the 1mm vibration test. The experimental results of this paper can be used as the reference data for the design of the optical fiber cable splicing enclosure to protect the optical loss variation due to environmental changes.

• Geomechanics and Engineering
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• 제30권4호
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• pp.383-392
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• 2022

Although pipelines are composed of segmental tubes commonly connected by rubber gasket or push-in joints, current studies mainly simplified pipelines as continuous structures. Effects of joints on three-dimensional deformation mechanisms of existing pipelines due to tunnel excavation are not fully understood. By conducting three-dimensional numerical analyses, effects of pipeline burial depth, tunnel burial depth, volume loss, pipeline stiffness and joint stiffness on bending strain and joint rotation of existing pipelines are explored. By increasing pipeline burial depth or decreasing tunnel cover depth, tunneling-induced pipeline deformations are substantially increased. As tunnel volume loss varies from 0.5% to 3%, the maximum bending strains and joint rotation angles of discontinuous pipelines increase by 1.08 and 9.20 times, respectively. By increasing flexural stiffness of pipe segment, a dramatic increase in the maximum joint rotation angles is observed in discontinuous pipelines. Thus, the safety of existing discontinuous pipelines due to tunnel excavation is controlled by joint rotation rather than bending strain. By increasing joint stiffness ratio from 0.0 (i.e., completely flexible joints) to 1.0 (i.e., continuous pipelines), tunneling-induced maximum pipeline settlements decrease by 22.8%-34.7%. If a jointed pipeline is simplified as a continuous structure, tunneling-induced settlement is thus underestimated, but bending strain is grossly overestimated. Thus, joints should be directly simulated in the analysis of tunnel-soil-pipeline interaction.

• 대한전자공학회논문지
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• 제24권4호
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• pp.696-700
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• 1987

Guide modes in a graded index multinmode optical fiber are turned into clad modes when the optical fiber was bended into a perpendicular direction to its optical axes by microbending forces, which causes the loss of the guiding optical power. The theories reported on this microbending power loss can be applied to calculation of the transmission power loss only when the beding period equals to the mode coupling length. In this paper, we obtained the general expression of the optical power transmission loss in a graded index multimode fiber bended periodically. This can be applied to the calculation of the power loss of the periodically microbended fiber with an arbitrary bending shape and period. Also, by using the beam theory in mechanics, we could derive the expression of the displacement of the optical fiber caused by the external force which bends the fiber into a periodic trapezoidal shape. Experiments were carried out to determine the dependence of the power loss on the period of the microbending forces. Experimnetal results were in good agreement (in the same order of the magnitude) with theoritical values derived in our work within the bending period region of 2mm-10mm.

• 대한가정학회지
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• 제36권8호
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• pp.51-61
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• 1998

This paper discussed the assessment of hand of polyester fabrics changed by alkaline hydrolysis. This study analyzed the relations between the change of mechanical property and the hand value according to the weight loss of polyester fabrics. The results are as follows; Objective hand by KES-FB system, revealed that for tensile properties, as the weight loss increased, WT, RT increased and LT decreased. For bending properties, as the weight loss increased, B and 2HB showed smaller values. For shear properties, as the weight loss increased, G, 2HG and 2HG5 decreased. For surface properties, as the weight loss increased, MIU increased, but MMD and SMD did not show any trend. For compression properties, LC, WC and RC did not show significant differences according to the degree of weight loss. In case of hand value, Koshi(stiffness), Hari(anti-drape stiffness), Kisimi(scrooping feeling) and Shinayakasa(flexibility with soft feeling) showed a meaningful results depending on the degree of weight loss. However, Shari(crispness) and Fukurami(fullness and softness) did not show meaningful result. Koshi, Hari and Shinayakasa are high correlation with tensile property, bendibg property shear properties, thickness and weight. Kisimi is high correlation with tensile property, bending property, thickness and weight. Shari, Fukurami and THV did not show any meaningful difference whth any mechanical properties.

• Journal of the Korean Wood Science and Technology
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• 제12권2호
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• pp.10-19
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• 1984

The $3{\times}3{\times}30$ ($cm^3$) sized lumbers of Populus alba-grandulosa L. were treated with four fire-retardant solutions of ammonium sulfate, monoammonium phosphate, diammonium phosphate and aluminium chloride for 1, 15, 30, and 60 minutes and 1, 3, and 7 days. Thereafter they were air-dried and burned at high temperature about $1,800^{\circ}C$ and for short time of five minutes. This study estimated the relationship between absorbed chemical amounts and rate of weight loss or residual bending strength of these burned lumbers. The results were as follows: 1) In absorption amount of fire-retardant chemicals, diammonium phosphate showed the largest, aluminium chloride the smallest, but monoammonium phosphate and ammonium sulfate showed similar level. 2) The absorption amount of chemicals was decreased with the increase of specific gravity in the same species except aluminium chloride. 3) The rate of weight loss was decreased as the absorption amount of chemicals increased, especially monoammonium phosphate was most effective. 4) The MOR value of the residual bending strength was increased as the absorption amount of chemicals increased and especially monoammonium phosphate showed the most efficient effect. 5) Aluminium chloride showed more striking increase of MOR value of residual bending strength with the increase of absorption amount than any other chemical, therefore its MOR value was similar to the maximum MOR value of the most effective monoammonium phosphate. 6) The correlation between weight loss and MOR value of the residual bending strength was negative and aluminium chloride showed the most striking negative relation, but the others showed similar trends. 7) The correlation between work to proportional limit and absorption amount of chemicals was positive and the degree of increase in work to proportional limit was most in aluminium chloride, and the next, in monoammonium phosphate and diammonium phosphate in turn. 8) The correlation between work to maximum load and absorption amount of chemicals showed positive and diammonium phosphate revealed the best result and aluminium chloride showed better results than other two chemicals.

• 한국광학회지
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• 제6권4호
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• pp.379-384
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• 1995

광대역 종합통신망 구축을 위해서는 저손실 및 넓은 대역폭을 갖는 광섬유의 사용이 필수적이며 또한 가입자까지 선로를 광케이블화 하기 위해서는 다심광케이블이 필요하다. 다심광케이블의 고밀도 실장 및 일괄접속을 만족하는 케이블 구조로는 리본광섬유가 폭을 가지고 있어 리본광케이블의 구부림시 광섬유 각각의 길이차에 의해 손실이 발생할 수 있기 때문에 유니트의 저장 및 제조상 주의가 필요하다. 본 연구에서는 리본광 케이블 유니트의 구부림 반경에 따른 광섬유의 스트레인과 구부림반경을 이론적으로 계산하였고 또한 손실의 원인인 측압을 계산하였다. 그리고 실험적으로 여러 유니트의 구부림반경에 따라 각 광섬유의 손실을 측정한 결과 이론적 분석 결과와 잘 부합됨을 알 수 있었다. 이 결과는 리본광케이블 제작시 리본광케이블 유니트의 보관 및 제조공정중에 사용할 릴의 적정 반경을 결정하는 것의 중요성을 보여준다.