• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.291-294
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• 2013

• Safety and Health at Work
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• 제1권1호
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• pp.98-101
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• 2010

This study explored the health hazard of those exposed to methylene chloride by assessing its atmospheric concentration when a tear gas mixture was aerially dispersed. The concentration of methylene chloride ranged from 311.1-980.3 ppm (geometric mean, 555.8 ppm), 30 seconds after the dispersion started. However, the concentration fell rapidly to below 10 ppm after dispersion was completed. The concentration during the dispersion did not surpass the National Institute for Occupational Safety and Health 'immediately dangerous to life or health' value of 2,300 ppm, but did exceed the American Conference of Governmental Industrial Hygienists excursion limit of 250 ppm. Since methylene chloride is highly volatile (vapor pressure, 349 mmHg at $20^{\circ}C$), the post-dispersion atmospheric concentration can rise instantaneously. Moreover, the o-chlorobenzylidenemalononitrile formulation of tear gas (CS gas) is an acute upper respiratory tract irritant. Therefore, tear gas mixtures should be handled with delicate care.

• 한국식품영양과학회지
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• 제34권3호
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• pp.356-360
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• 2005

장의 건강을 유지하기 위해서는 식이섬유, 장내세균총, 소화 상피세포와 점액질층(mucus layer)을 포함하는 점액질(mucosa)의 3대 요소가 상호보완 및 균형 관계가 중요하다. 특히 점액의 분비와 점액층의 형성이 제대로 이루어져야 하며 각종 장질환의 거의 대부분은 뮤신의 부족과 깊은 관계가 있는 보고 자료를 참고하여 식물성 복합추출물인 장기능 개선제 KTG075의 장기능 개선 효과 및 배변촉진 효과를 알아보기 위해 랫드의 대장 내 점액(mucin)의 분비에 미치는 영향을 조사하였다. Loperamide를 투여하여 변비를 유발시킨 랫드에 장기능개선제 KTG075를 투여한 후 대장 내 변의 수를 관찰한 결과, loperamide 단독 처 리군보다 변의 수가 68.2% 감소하는 것이 관찰되었으며, 대장 내 점액질 층의 두께 측정시는 loperamide단독 처리군은 정상 대조군에 비해 랫드의 대장 내에 분비되는 점액질의 두께가 약 31%가 감소하였으나, KTG075 동시 처리군에서는 점액질의 두께가 정상적으로 회복되는 것이 조직검사에서 관찰되었으며, Alcian blue 염색으로 점 액 질 두께 변화 관찰 시는 lopreamide 단독 처리군에서 현저히 감소되었고 KTG075 동시처리군에서는 점액질 층이 거의 정상수준으로 증가되었다. 결과적으로, loperamide 단독처리군에서는 점액질(mucus)의 생성과 분비가 감소되나, 장기능개선제인 KTG075는 장기능을 활성화시킴으로써 점액의 분비를 증가시켜 증가된 점액이 대장 내 윤활제로서 작용하여 장관 운동을 증가시켜 배변을 용이하게 하여 변비 또는 스트레스 등에 의해 저하된 장 기능을 개선시키는 것으로 판단되었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1997년도 추계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.7-7
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• 1997

During sintering of very porous green bodies, as obtained by compaction of hard powders - such as tungsten carbide or ceramics - or by injection moulding, important shrinkage occurs. Due to heterogeneous green density field, gravity effects, friction on the support, thermal gradients, etc., this shrinkage is often non-uniform, which' may induce significant shape changes. As the ratio of compact dimension to powder size is very high, the mechanics of continuum is relevant to model such phenomena. Thus numerical techniques, such as the finite element method can be used to simulate the sintering process and predict the final shape of the sintered part. Such type of simulation has much been developed in the last decade firstly for hot isostatic pressing and next for die compaction. Finite element modelling has been recently applied to free sintering. The simulation of sintering should be based on constitutive equations describing the thermo-mechanical behaviour of the material under any state of stress and any temperature which may arise within the sintering body. These equations can be drawn either from experimental data or from micromechanical models. The experiments usually consist in free sintering and sinter-forging tests. Indeed applying more complex loading conditions at high temperature under controlled atmosphere is delicate. Micromechanical models describe the constitutive behaviour of aggregates of spheres from the deformation of two-sphere contact either by viscous flow or grain boundary diffusion. Such models are not able to describe complex microstructure and mechanisms as observed in real materials but they can give some basic information on the formulation of constitutive equations. Practically both experimental and theoretical approaches can be coupled to identify the constitutive equations. Such procedure has been performed for modelling the sintering of compacts obtained by die pressing of a mixture of tungsten carbide and cobalt powders. The constitutive behaviour of this material during sintering has been described by a linear viscous constitutive model, whose functions have been fitted from results of free sintering and sinter-forging experiments. This model has next been introduced in ABAQUS finite element code to simulate the sintering of heterogeneous green compacts of various geometries at constant temperature. Examples of simulations are shown and compared with experiments.

• 한국생산제조학회지
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• 제25권4호
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• pp.266-270
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• 2016

We present a useful and practical manufacturing technique that enables the structural conversion of delicate as-grown nanostructures to more beneficial and robust thin-film frameworks through controlled mechanical rolling. Functional nanostructures such as carbon nanotubes grown through chemical vapor deposition in a vertically aligned and very loosely packed manner, and thus difficult to manipulate for subsequent uses, can be prepared in an array of thin blades by patterning the growth catalyst layer. They can then be toppled as dominos through precisely controlled mechanical rolling. The nanostructures formulated to horizontally aligned thin films are much more favorable for device applications typically based on thin-film configuration. The proposed technique may broaden the functionality and applicability of as-grown nanostructures by converting them into thin-film frameworks that are easier to handle and more durable and favorable for fabricating thin-film devices for electronics, sensors, and other applications.