• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.9-12
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• 2001

Composite materials can be used economically and efficiently in broad civil engineering applications when standards and processes for analysis, design, fabrication, construction and quality control are established. Many of the bridge systems, including the girders and cross-beams, and concrete decks behave as the special othotropic plates. Such systems with boundary conditions other than Navier or Levy solution types, or with irregular cross sections, analytical solution is very difficult to obtain. Numerical method for eigenvalue problems are also very much involved in seeking such a solution. A method of calculating the natural frequency corresponding to the first mode of vibration of beam and tower structures with irregular cross-sections was developed and reported by the author in 1974 Recently, this method was extended to two dimensional problems including composite laminates, and has been applied to composite plates with various boundary conditions with/without shear deformation effects and reported at several international conferences including the Eighth Structures Congress of American Society of Civil Engineers in 1990. In this paper, the result of application of this method to the special orthotropic plates with various boundary condition is presented.

• Structural Engineering and Mechanics
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• 제76권4호
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• pp.505-512
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• 2020

This paper presents an error estimation technique for 2-D crack analysis by an enriched natural element (more exactly, enriched Petrov-Galerkin NEM). A bare solution was approximated by PG-NEM using Laplace interpolation functions. Meanwhile, an accurate quasi-exact solution was obtained by a combined use of enriched PG-NEM and the global patch recovery. The Laplace interpolation functions are enriched with the near-tip singular fields, and the approximate solution obtained by enriched PG-NEM was enhanced by the global patch recovery. The quantitative error amount is measured in terms of the energy norm, and the accuracy (i.e., the effective index) of the proposed method was evaluated using the errors which obtained by FEM using a very fine mesh. The error distribution was investigated by calculating the local element-wise errors, from which it has been found that the relative high errors occurs in the vicinity of crack tip. The differences between the enriched and non-enriched PG-NEMs have been investigated from the effective index, the error distribution, and the convergence rate. From the comparison, it has been justified that the enriched PG-NEM provides much more accurate error information than the non-enriched PG-NEM.

• 생명과학회지
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• 제21권4호
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• pp.584-588
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• 2011

본 연구에서는 유기농자재인 키토산, 목초액 및 EM 활성액 등을 공시재료로, 배추 정식 전에 100배액 토양관주 처리하고, 배추 정식 후 15일 간격으로 엽면살포 농도를 100배액과 1,000배액으로 3회 엽면살포한 후 배추의 생육 및 토양 미생물상의 변화에 대해 분석하였다. 유기농자재 처리에 따른 배추의 생육특성은 대조구에 비해 유기농자재 처리구에서 생육이 양호하게 나타났으며, 유기농자재 간에는 키토산 처리구에서 양호하였고, 특히 키토산 1,000배액 처리구에서 생육이 양호하였으며, 주중이 5.60 kg으로 가장 무거웠다. 유기농자재 처리에 따른 토양 미생물상 변화는 대조구에 비해 유기농자재 처리구에서 세균, 트리코데마 및 방선균수은 증가한 경향을 보였고, 사상균수는 약간 감소한 경향을 보였으나 처리간 일정한 경향은 없었다. 유기농처리구 간에는 키토산 1,000 배액 처리구에서 세균, 트리코데마 및 방선균수가 가장 많이 증가하였다.

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.705-707
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• 2008

• 대한가정학회지
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• 제40권11호
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• pp.93-105
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• 2002

Nylon fabrics and stocking were dyed with artemisia dyeing solution, dyed with the natural dyestuffs that were manufactured from chestnut hulls by boiling in 0.5% NaOH solution and powdering in freeze dryer, and dyed with gromwell dyeing solution. Dyeabilities on nylon fabrics and stocking were good because of being amine group. All the dyed fabrics & stocking showed excellent in color fastness to laundering, and as poor as grade 1 to light fastness. But Light fastness of them could be improved to grade 3 or 4-5 by treatment with gallic acid and by repeated dyeing. Antimicrobial activities of the fabrics dyed with artemisia and gromwell against Staphylococcus aureus and Candida albicans were excellent in the aspect of bacteriostatic and fungistatic. There were not any distinct differences between mordant and non-mordant fabrics.

• 한국환경보건학회지
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• 제17권2호
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• pp.95-101
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• 1991

Lead acetate solution were intraperitoneally injected to rats of average body weight 220g to cause lead poisoning. Antidotes were orally administered using catheter to the rats and the urine was collected after 24 hours. ALA in the urine were determined by U. V. spectrophotometer. Antidotes used in this experiment were the water extracts of scutellaria radix and D-penicillamine solution. ALA in the urine was determind by Wada method. It was found that ALA content in the urine was decreased after oral administration of water extracts of scutellaria radix and D-penicillamine solution. In this study it is believed that water extract of suctellaria radix could be used as an excellent antidate in lead poisoning.

• 복식문화연구
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• 제12권5호
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• pp.781-791
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• 2004

Currently, as mordants, heavy metals are being used in dyeing process in order to improve dye uptake and dye fastness. These chemicals, however, are mostly harmful to human body and the environment along with the pollution by effluent. Traditionally, rice straw ash solution, lime, etc. have been used as mordants in order to improve the effects on dye uptake and color fastness of dyestuffs. The study of natural mordants would, therefore, be vital to the development and succession of our traditional dyeing methods. In this study, as a preliminary step toward the use of rice straw ash solution for the nautral dyeing using Caesalpinia sappan, several aluminum compounds were employed as mordants. When the purified aluminum compounds were used, on the basis of unmordanted cotton fabric, the K/S values of the pre-mordanted and simultaneously mordanted fabrics increased by 2 or 3 times, while those of the post-mordanted fabrics decreased.

• Structural Engineering and Mechanics
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• 제35권5호
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• pp.645-658
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• 2010

In this study, the Differential Transform Method (DTM) is employed in order to solve the governing differential equation of a moving Bernoulli-Euler beam with axial force effect and investigate its free flexural vibration characteristics. The free vibration analysis of a moving Bernoulli-Euler beam using DTM has not been investigated by any of the studies in open literature so far. At first, the terms are found directly from the analytical solution of the differential equation that describes the deformations of the cross-section according to Bernoulli-Euler beam theory. After the analytical solution, an efficient and easy mathematical technique called DTM is used to solve the differential equation of the motion. The calculated natural frequencies of the moving beams with various combinations of boundary conditions using DTM are tabulated in several tables and are compared with the results of the analytical solution where a very good agreement is observed.

• 한국해양공학회지
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• 제13권1호통권31호
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• pp.121-129
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• 1999

Double-diffusive convection with verical temperature and concentration gradients in thermally stratified fluids has been investigated experimentally using an electrochemical technique. Cupric sulfuric-sulffuric acid solution confined between two horizontal copper electrodes was used. The change of thermal and solutal buoyance has no influence on the range of voltage for the limiting current. Due to Soret effect, the onset time of natural convection is delayed as the stabilizing thermal buoyancy decreases. Also it is found that the shrinkage of the unstabilizing solutal buoyancy makes the onset of natural convection retard. Multi-layered convective phenomena do not appear because cupric sulfate-sulfuric acid solution is thermally stratified, and heat diffuses faster than cupric sulfate solfate solution.

• 접착 및 계면
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• 제19권2호
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• pp.60-67
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• 2018

본 연구에서는 친환경 천연섬유인 케나프의 표면을 Chemlok 402를 함유하고 있는 접착용액으로 전처리하였을 경우, 케나프/천연고무 복합재료의 경화거동, 경도, 인장특성 그리고 마모특성에 미치는 섬유 표면처리 유 무, 섬유함량 및 섬유길이의 영향을 조사하였다. 복합재료를 구성하는 케나프섬유 함량은 평균 케나프섬유의 길이가 약 2 mm로 일정한 상태에서 각각 0, 5, 10, 15, 20 phr로 달리하였다. 또한 섬유함량이 5 phr로 고정된 상태에서 평균 섬유길이는 각각 2 mm, 35 mm, 70 mm로 달리하여 각 특성을 비교하였다. 천연고무 복합재료의 경화거동을 나타내는 Tmax 값과 tc90 값, Shore A 경도, 인장탄성률 그리고 마모저항성은 케나프섬유 함량과 길이에 크게 의존하였다. 이러한 특성들은 케나프섬유의 표면을 접착용액으로 전처리한 경우가 처리하지 않은 경우보다 더 우수한 특성을 나타냈다. 이러한 현상은 전처리된 케나프섬유와 고무매트릭스 사이의 계면접착 상태가 개선되었기 때문이다. 본 연구결과는 천연섬유강화 복합재료의 물성을 향상시키기 위해 접착용액의 적절한 사용이 가능하다는 것을 제시하여 준다.