• 한국연초학회지
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• 제13권1호
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• pp.74-81
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• 1991

This study was conducted to find out physical and chemical characteristics of burley and flue-cured tobacco leaves followed by location, growing season and leaf position during the period 1985 to 1989. The locations of flue-cured tobacco were 7(65farms) and burley tobacco were 4(40 farms). 1. Flue-cured tobacco leaves The locations of Ch'unch'on and Suwon were higher nicotine and ether extract content, Taegu and Chinju were higher total nitrogen content but Chiniju was lower red color of cured leaves than that of other location. Nicotine content increased but total sugar content decreased during the period 1985 to 1989. Nicotine and total nitrogen content increased but crude ash decreased from lower leaf position to higher leaf position. Total sugar and ether extract content were variable followed by leaf position. 2. Burley tobacco leaves. The location of Ch'onju was higher ether extract content than that of others location, but there was no significant difference the others chemical component among location. Nicotine content and red color of cured leaves increased during the period 1985 to 1989. Nicotine, total nitrogen and ether extract content increased but decreased crude ash content and brightness of cured leaf from lower leaf position to higher leaf position.

• 한국산업융합학회 논문집
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• 제2권1호
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• pp.45-52
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• 1999

It is difficult to keep the balance of supply and demand for natural aggregates in recent years, because natural resources have become to be almost exhausted. Crushed stone is already used for coarse aggregate instead of river gravel at present. Now, crushed sand or sea sand should be used for fine aggregate, because natural sand also has been exhausted with a few exceptions around Nakdong River. The sea sand has a lot of problems which are the corrosion of reinforcement bars, the investment of facility for cleansing salt and the cost increase due to the insufficiency of industrial water. Therefore, it is necessary to produce and to utilize the crushed sand very actively, but some material properties which are related to water absorption, strength and chemical durability, prevent from determining the generalized criteria because its rocks make much differences in its physical and chemical characteristics. In this paper, fundamental physical properties of crushed sand, which comes from Daegu Subway construction fields, have been investigated for the usability on basic material of concrete. The optimum replacement ratio and the strength estimation method of crushed sand replacing natural sand also have been presented here through the compressive strength test of ready-mixed concrete cylinders.

• Elastomers and Composites
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• 제30권3호
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• pp.195-206
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• 1995

To modify the NBR rubber roll which has poor abrasion and chemical resistance, NBR/PVC blends were prepared in various composition ratios. First of all, their miscibility and vulcanization characteristics were investigated. Their abrasion and chemical resistant properties and physical properties were also studied. DSC thermograms for NBR/PVC blends show only one Tg in the entire composition range, demonstrating a perfect miscibility. In the vulcanization characteristics tested by rheometer, maximum torque decreases as PVC contents increased. In the investigation of physical properties of NBR/PVC blends, hardness increases and elongation decreases along with the increasing contents of PVC. On the other hands, tensile strength increases with the increasing contents of PVC up to 11.1 wt. %, and then decreases with higher contents of PVC. While the abrasion resistance of NBR/PVC blends was similar to that of NBR itself, the chemical resistance of NBR/PVC blends was superior to that of NBR.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.196-200
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• 2011

In this work, poly(methyl methacrylate) (PMMA) was grafted onto amine treated graphite nanosheets ($NH_2$-GNs) and the surface characteristics and physical properties of the $NH_2$-GNs-g-PMMA films were investigated. The graft reaction of $NH_2$-GNs and PMMA was confirmed from the shift of the $N_{1S}$ peak, including amine oxygen and amide oxygen, by X-ray photoelectron spectroscopy (XPS). The surface characteristics of the $NH_2$-GNs-g-PMMA films were measured as a function of the $NH_2$-GN content using the contact angle method. It was revealed that the specific component of the surface free energy (${\gamma}s$) of the films was slightly increased as the $NH_2$-GN content increased. Also, the thermal and mechanical properties of the $NH_2$-GNs-g-PMMA films were enhanced with the addition of $NH_2$-GNs. This can be attributed to the chemical bonding caused by the graft reaction between the $NH_2$-GNs and the PMMA matrix.

• 대한화학회지
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• 제19권4호
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• pp.258-268
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• 1975

유기폐물을 다량으로 배출하는 산업중에서 대표적인 제지·펄프공업, 식품공업을 선택하여 고형유기폐물과 폐수처리오니의 합리적인 자원화 방법으로서 이들물질의 비료적 가치 및 humus원으로서의 개발가치를 중심으로 이들 물질의 물리적 및 화학적 특성을 조사한 결과이다. 제지${\cdot}$펄프공업 유기고형폐물은 비료성분이 적고 lignin 함량이 높아 비료로서 보다는 humus화하여 토양개량제로서 개발하는 것이 합리적이다. 제혁공업 폐수처리오니는 비료로서 효과도 기대되어 산성토양 개량효과도 기대되나 다량으로 함유한 Cr 으로 인해 오염효과가 문제가 된다. 식품공업의 고형 유기폐물 또는 폐수처리오니는 비료로서 또는 미량요소 공급원으로서 가치가 인정되며 수용성 당류의 량이 높거나 C/N율이 20이하로 낮은 물질은 속성 humus화를 위한 첨가 재료로서의 가치도 인정된다.

• 한국막학회:학술대회논문집
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• 한국막학회 1996년도 추계 총회 및 학술발표회
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• pp.86-87
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• 1996

IPN (Interpenetrating Polymer Network) is a mixture of two or more crosslinked polymers with physically interlocked network structures between the component polymers. IPN can be classified as an alloy of thermosets and has the characteristics of thermosets such as the thermal resistance and chemical resistance and also has the characteristics of polymer alloys with enhanced impact resistance and amphoteric properties. The physical interlocking during the synthesis restricts the phase separation of the component polymer with chemical pinning process, thus the control of morphology is possible through variations of the reaction temperature and pressure, catalyst concentration and crosslinking agent concentration. Finely dispersed domain structure can be obtained through IPN synthesis of polymer components with gross immiscibility. In membrane applications, particularly for the separation of liquid mixtures, crosslinked polymer component with specific affinity to the permeate is needed. With the presence of the permeant-inert polymer component, the mechanical strength and the selectivity of the membranes are enhanced by restricting the swelling of the transporting polymer component networks.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.215-222
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• 2004

본 논문에서는 고분자의 바인더와 고체불질 사이의 결합력을 증진시켜 물성을 향상시키는 역할과 화학결합에 의한 두 재질간의 접착력을 향상시킬 목적으로 사용되는 Aziridine계 bonding agent를 합성하여 이화학 특성을 분석하고 이를 라이너에 적용하였을 때 불성 및 접착력 특성에 관한 연구를 하였다. 비교 실험을 진행하기 위해 미국 3M사에서 제조한 HX-868을 통일한 조건에서 사용했고 미국규격에 규정된 항목과 각 항목에 대한 표준화된 방법으로 분석하였다. 그 결과 국내기술로 합성한 HX-868이 미국에서 제조된 HX-868과 통일한 품질 수준으로 갖는 것으로 평가되었다.

• 한국농공학회논문집
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• 제54권2호
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• pp.127-135
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• 2012

The processes of chemical and physical weathering occur simultaneously. The objective of this study was to estimate the degree weathered using fractal dimension through comparison with chemical characteristic of soil samples from Pohang (PH) and Kimpo (KP). Comparing chemical characteristics with fractal dimension, $SiO_2$, $Na_2O$, $K_2O$ content decreased and loss of ignition increased as fractal dimension increased. And fractal dimension showed high correlation with CWI while ATI, STI CIW, PI, CIA and RR demonstrated different degrees of correlation with fractal dimension. The tendency of the changes in oxide content and chemical weathering index with increasing fractal dimension appeared to be similar with the chemical changes due to weathering. Therefore, fractal dimension could be a good indicator representing the extent of weathering and chemical changes.

• 한국작물학회지
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• 제50권2호
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• pp.120-124
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• 2005

Expanded rice husk (ERR) is different from commercial rice seedling media in chemical and physical properties such as pH, permeability, and water content. This study was conducted to test a possibility of improving rice seedling growth by improving the texture of ERR as a rice seedling medium. The seedling media used were a commercial seedling medium (CSM), rice husk, and ERR 1, 2, 3, and 4 with different expansion degrees. The pH of the ERHs ranged from 6.3 to 6.8. As the expansion rate increased, ERR particle sizes decreased, and water permeability and absorption rates improved. No significant differences in shoot dry weight and rate of maturity were found among the seedlings cultivated in the different ERH media. However, the mat formation of seedling roots became loose as the expansion rates were decreased. Further studies are necessary to determine the cause of poor root growth in ERH media.

• The Journal of Korean Physical Therapy
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• 제12권2호
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• pp.203-217
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• 2000

This review describes the overall knowledges of parkinson's disease. There are involved the causes. chemical characteristics, clinical features including tremor. bradykinesia, and rigidity. evaluation of movement disorders. and physical therapy of parkinson's disease. People who are diagnosed with parkinson's disease experience movement disorders that, if not managed, can lead to considerable disability. Before treated with parkinson's disease, it is important to recognise the pathogenesis of that. Then we need to develop physiotherapeutic programs based on the pathophysiology of parkinson's disease.