• Structural Engineering and Mechanics
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• 제13권4호
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• pp.369-385
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• 2002

Ductility capacity is comprehensively studied for steel moment-resisting frames. Local, story and global ductility are being considered. An appropriate measure of global ductility is suggested. A time domain nonlinear seismic response algorithm is used to evaluate several definitions of ductility. It is observed that for one-story structures, resembling a single degree of freedom (SDOF) system, all definitions of global ductility seem to give reasonable values. However, for complex structures it may give unreasonable values. It indicates that using SDOF systems to estimate the ductility capacity may be a very crude approximation. For multi degree of freedom (MDOF) systems some definitions may not be appropriate, even though they are used in the profession. Results also indicate that the structural global ductility of 4, commonly used for moment-resisting steel frames, cannot be justified based on this study. The ductility of MDOF structural systems and the corresponding equivalent SDOF systems is studied. The global ductility values are very different for the two representations. The ductility reduction factor $F_{\mu}$ is also estimated. For a given frame, the values of the $F_{\mu}$ parameter significantly vary from one earthquake to another, even though the maximum deformation in terms of the interstory displacement is roughly the same for all earthquakes. This is because the $F_{\mu}$ values depend on the amount of dissipated energy, which in turn depends on the plastic mechanism, formed in the frames as well as on the loading, unloading and reloading process at plastic hinges. Based on the results of this study, the Newmark and Hall procedure to relate the ductility reduction factor and the ductility parameter cannot be justified. The reason for this is that SDOF systems were used to model real frames in these studies. Higher mode effects were neglected and energy dissipation was not explicitly considered. In addition, it is not possible to observe the formation of a collapse mechanism in the equivalent SDOF systems. Therefore, the ductility parameter and the force reduction factor should be estimated by using the MDOF representation.

• Steel and Composite Structures
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• 제25권1호
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• pp.79-92
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• 2017

Initial damage to a stud due to corrosion, fatigue, unexpected overloading, a weld defect or other factors could degrade the shear capacity of the stud. Based on typical push-out tests, a FEM model and theoretical formulations were proposed in this study. Six specimens with the same geometric dimensions were tested to investigate the effect of the damage degree and location on the static behavior and shear capacity of stud shear connectors. The test results indicated that a reduction of up to 36.6% and 62.9% of the section area of the shank could result in a dropping rate of 7.9% and 57.2%, respectively, compared to the standard specimen shear capacity. Numerical analysis was performed to simulate the push-out test and validated against test results. A parametrical study was performed to further investigate the damage degree and location on the shear capacity of studs based on the proposed numerical model. It was demonstrated that the shear capacity was not sensitive to the damage degree when the damage section was located at 0.5d, where d is the shank diameter, from the stud root, even if the stud had a significant reduction in area. Finally, a theoretical formula with a reduction factor K was proposed to consider the reduction of the shear capacity due to the presence of initial damage. Calculating K was accomplished in two ways: a linear relationship and a square relationship with the damage degree corresponding to the shear capacity dominated by the section area and the nominal diameter of the damaged stud. This coefficient was applied using Eurocode 4, AASHTO LRFD (2014) and GB50017-2003 (2003) and compared with the test results found in the literature. It was found that the proposed method produced good predictions of the shear capacity of stud shear connectors with initial damage.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2021년도 추계학술대회
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• pp.41-44
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• 2021

In this paper, we propose an efficient reference-based compression artifact reduction network for 360-degree images in an equi-rectangular projection (ERP) domain. In our insight, conventional image restoration methods cannot be applied straightforwardly to 360-degree images due to the spherical distortion. To address this problem, we propose an adaptive disparity estimator using a deformable convolution to exploit correlation among 360-degree images. With the help of the proposed convolution, the disparity estimator establishes the spatial correspondence successfully between the ERPs and extract matched textures to be used for image restoration. The experimental results demonstrate that the proposed algorithm provides reliable high-quality textures from the reference and improves the quality of the restored image as compared to the state-of-the-art single image restoration methods.

• 자원리싸이클링
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• 제2권4호
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• pp.10-16
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• 1993

마이크로파 가열 공정에 의하여 스테인레스강 제조시의 발생하는 분진의 환원거동올 환원제로서 코크스와 목탄을 이용하여 조사하였다. 원래 상태의 펠릿 분진과 환원제로서, 펠릿을 만든 분진을 마이크로파 가열오븐 내에서 $1000^{\circ}C$까지 가열하여 환원시켰다. 코크스에 비하여 목탄의 경우가 더 높은 환원율율을 나타내었다. 마이크로파 오븐에서 500W와 700W의 사용한 경우 유사한 환원율을 나타냈으며 200분 이내에 급속하게 환원되였다. 환원정도는 Fe>Ni>Cr로 감소되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.659-663
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• 1997

In this paper, a simplified vibration analysis model for bellows was presented to avoid excessive effort required for shell model. To reduce degree of freedom, bellows was modelled using one dimensional beam element. The equivalent mass and stiffness matrices were obtained based upon Guyan reduction process. The results were compared with the confirmed results, which were in good agreement.

• 대한물리치료과학회지
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• 제21권1호
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• pp.53-58
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• 2014

Background : The purpose of this study is to identify the level of positive influence on the pain and the gripping power in patients with tennis elbow by comparing the TENS treatment method and the kinesio taping therapy with good accessibility among the kinesio taping therapy and electrical therapy. Methods : Targeting the patients diagnosed with tennis elbow, the subjects were categorized in groups of four, each of electrical therapy group and kinesio tape therapy group where the degree of pain reduction through VAS before and after the treatment of each group and the measurement of the degree of gripping power increase using the gripping power measurement tool as well as the pain reduction changes and gripping power increase before and after the treatment between the two groups were compared. Result : As a result, the electrical therapy group and the kinesio tape group were able to obtain the results of pain reduction and gripping power increase through VAS before and after the treatment, but for all pain reduction and gripping power increase, it had no statistically significant changes(p>.05). In addition, in the changes of pain reduction and changes of gripping power increase before and after the treatment, there were no statistically significant differences between the electrical therapy group and the kinesio tape group(p>.05). Conclusion : Based on the results so far, it is thought that the kinesio taping therapy can positively influence the pain reduction of patients with tennis elbow and increase of gripping power.

• Journal of Yeungnam Medical Science
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• 제11권1호
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• pp.167-180
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• 1994

좌우 경동맥을 결찰하여 혈뇌장벽에 변화를 일으킨 백토에서 뇌압하강제(mannitol, steroid) 및 뇌압하강 방법(과호흡)의 효과를 관찰하였다. Mannitol군에서는 steroid군, 과호흡군에 비해 뇌압감소가 통계적으로 유의하게 있었으며, 시간적으로 mannitol 투여 후 25~30분까지 뇌압이 45%까지 감소하여 지속되었다. Steroid군에서는 mannitol군보다는 뇌압 절대치의 감소폭은 적었지만, 과호흡군 보다 2배 이상의 뇌압감소가 있었고, mannitol군보다 더욱 오랫동안 뇌압감소의 효과가 지속되었다. 과호흡군에서는 mannitol군, steroid군에서보다는 뇌압감소 효과가 적었으나, 과호흡 시행 후 10분까지 13.5~16.7%의 뇌압감소가 있었고, 그 이후 시간 경과에 따른 더 이상의 뇌압감소 효과는 없었다. Mannitol, steroid, 과호흡군을 모두 시행한 복합치료군에서는 mannitol 및 steroid, 과호흡을 각각 시행한 군에서보다 뇌압 감소가 더욱 현저하게 이루어져 30분까지 48~52%의 뇌압감소가 있었다. 이상의 결과로 미루어보아 뇌허혈성 뇌졸중 환자에서 mannitol 및 steroid사용과 병행하여 과호흡을 실시함으로써 뇌압감소를 위한 적절한 치료의 지표가 될 것이라 판단다.

• 대한영양사협회학술지
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• 제6권2호
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• pp.71-78
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• 2000

Environmental pollution induced by food wastes is considered as one of very serious problems in the world, and it is the most important to reduce the production of food wastes. In this study, environmental campaign for reducing food waste was conducted by applying various campaign methods using such as a bulletin board, intra-network, slogans & posters and news letters, as well as some systems such as penalty and prize in a business & industry foodservice. We investigated customers' recognition and execution degree before and after environmental campaign for the purpose of analyzing the changes of customers' attitude by the campaign. The subjects of this study had generally high level of recognition of environmental problem(3.09 point) compared to the execution degree(1.88 point)(Max. 5 points), implying necessity for the induction of actual execution of food wastes reduction by continuous environmental campaign. After environmental campaign, the recognition of environmental problem related to food wastes was significantly increased from 3.09 point to 3.29 point (p<0.001), and the execution degree for food wastes reduction was also greatly increased from 1.88 to 2.70 point (p<0.001). These changes indicated that campaign for food wastes reduction has raised customers' recognition and execution for environmental protection.

• 한국수소및신에너지학회논문집
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• 제20권1호
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• pp.45-54
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• 2009

Reduction reactivity and carbon deposition characteristics of three oxygen carrier particles(OCN01, OCN02, OCN03) have been investigated by using hydrogen, methane, syngas, and natural gas as fuels. For all particles, the maximum conversion, the oxygen transfer capacity, and the degree of carbon deposition increased as the reactive carbon contents increased. The reduction rate and the oxygen transfer rate increased as the moles of required oxygen per input gas increased. The change of maximum conversion, reduction rate, oxygen transfer capacity, oxygen transfer rate and degree of carbon deposition for different fuels can be explained consistently by using parameters such as the reactive carbon contents and the moles of require oxygen per input gas.

• 한국의류학회지
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• 제28권6호
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• pp.807-818
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• 2004

The antibacterial activities of several types of chitosan were measured against Staphylococcus aureus and evaluated for their application to antibacterial textile finishing. The ％ reduction of bacteria of the chitosans prepared in our laboratory were between 72 and 87%. The two water-soluble chitosans with molecular weights 1,000 and 3,000 did not show antibacterial activities. The deacetylation of chitosan was appeared to increase antibacterial activity. The ％ reduction in bacterial density of the 86％-deacetylated chitosan solution was 56% where that of the 76％-deacetylated chitosan solution was only 17％ at 0.1% chitosan concentration. Molecular weights of the chitosans seemed not to affect antibacterial activities of chitosans. The antibacterial activity of the acid-soluble, 86%-deacetylated chitosan with 4 cps showed 98% of the ％ reduction at the level of 0.2％ chitosan. The ％ reduction of bacteria of this chitosan was higher at the higher concentration of acetic acid in the chitosan-bacterial mixture. The antibacterial activity was increased with the pH change over the range of 4.0 to 6.5. The 100% of the ％ reduction of bacteria was achieved within 4 hour incubation of the chitosan-bacterial mixture. According to the data obtained from the above experiments, the four chitosans among the six prepared in our laboratory were proved to be valuable for antibacterial textile finishing.