• Journal of Forest and Environmental Science
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• 제18권1호
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• pp.97-105
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• 2001

The main objective of this study was to investigate effects of pigment mixed with different ratio on the double coated paper. Mineral pigments such as clay and ground calcium carbonate(GCC) as well as hollow sphere plastic pigment were used to evaluate the physical, optical properties and printabilities of double coated paper. The physical properties such as gloss and smoothness, and the printability(ink gloss) of double coated paper were measured to evaluate the effects of the bottom layer on improving the properties of top layer. The data indicated that the usage of hollow sphere plastic pigment for the bottom layer coating improved the surface properties of double coated paper, and that ink gloss was significantly influenced by the structure of bottom layer even when hollow sphere plastic pigment was used for the bottom layer coating.

• 전기학회논문지
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• 제56권12호
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• pp.2221-2225
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• 2007

Hollow-type microneedle array can be used for painless, continuous and stable drug delivery through a human skin. The needles must be sharp and have sufficient length in order to penetrate the epidermis. An array of hollow-type silicon microneedles was fabricated by using deep reactive ion etching and HNA wet etching with two oxide masks. Isotropic etching was used to create tapered tips of the needles, and anisotropic etching of Bosch process was used to make the extended length and holes of microneedles. The microneedles were formed by three steps of isotropic, anisotropic, and isotropic etching in order. The holes were made by one anisotropic etching step. The fabricated microneedles have $170{\mu}m$ width, $40{\mu}m$ hole diameter and $230{\mu}m$ length.

• 한국안전학회지
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• 제21권6호
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• pp.96-100
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• 2006

In this thesis, the crack investigation, the damage investigation, the drawing check, and the structural analysis were performed on a curved hollow RC(reinforced concrete) slab bridge structure to assess the structural safety of that. From the crack investigation result, main reason of crack occurrence is guessed with travelling of the large truck. Therefore reinforcement of slab structure is necessary by using the steel plate. When structural analysis, the straight beam model, the curved beam model, and the curved plate model is used. From the results of structural analysis for curved hollow RC slab bridge, the maximum bending moment and the maximum shear force was not a difference in each models. But the vertical displacement of mid span using the curved beam model was greater than that using the other models.

• Tribology and Lubricants
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• 제25권3호
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• pp.171-175
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• 2009

One of the critical issues associated with the 40mm long hollow cylinder's development and maintenance is the prediction of cylinder erosion. The actual firing test is the most accurate method to measure the cylinder erosion rate. But it costs a great deal and requires a long measurement time. Hence many empirical methods have been proposed to predict the erosion rate and life span of long hollow cylinders. An EFC formula is calculated. An approximate erosion formula for the ammunition type A is derived to interpolate 16 observation values up to 4,000 rounds. A new erosion equation and muzzle velocity formula are also suggested. Several numerical results are presented.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.183-186
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• 1995

A simulation method basee on upper bound method is developed in order to characterize forging characters in forging of spur gears. In this paer, utlizing a kinematically admissible velocity field and applying it to study the effect of inner diameter of holow billet. To predict the variation of inner diameter of hollow billet, neutal surface has been introduced into forging of hollow gears from hollow billes with flat punch. The neutral surface of each step is assumed as a circle and determined in order to have minimum forging energy by golden section method. According to the analysis, the magnitude of inner diameter of initial billet is vary important to reduce the relative pressure and forging load. And the variation of inner diameter of billet during spur gear forging is successfully predicted.

• 한국진공학회지
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• 제11권2호
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• pp.119-126
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• 2002

Hollow cathode discharge(HCD)에서 알곤 기체를 완충 기체로 사용하여 전류 변화에 따른 광검류 신호를 측정하였다. 광검류 신호는 방전의 전기 전도도의 증가 또는 감소에 의해 나타나며 전기 전도도의 변화는 전자 충돌에 의한 이온화율의 변화에 의해 일어난다. 낮은 방전 전류에서 광검류 신호는 가장 낮은 준안정 준위 원자의 밀도 변화와 밀접한 관계가 있다는 결론을 얻었다.

• International Journal of Aeronautical and Space Sciences
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• 제2권2호
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• pp.46-55
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• 2001

A Green's function approach based on the laminate theory is adopted to obtain the unsteady temperature distributions in a semi-infinite hollow circular cylinder made of functionally graded materials (FGMs). The transient heat conduction equation based on the laminate theory is formulated into an eigenvalue problem for each layer by using the eigenfunction expansion theory and the separation of variables. The eigenvalues and the corresponding eigenfunctions obtained by solving an eigenvalue problem for each layer constitute the Green's function solution for analyzing the unsteady temperature distributions. Numerical calculations are carried out for the semi-infinite hollow circular FGM cylinder subjected to partially heated loads, and the numerical results are shown in figures.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.44-52
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• 1997

As part of the effort to reduce the weight of powertrain, a hollow crankshaft has been designed. The mass reduction of the crankshaft changes the dynamic properties of the crankshaft such as moment of inertia, and torsional, bending stiffness. The purpose of this paper is to compare the dynamic behavior of the hollow crankshaft with that of the original, solid crankshaft. Global dynamic behavior of the crankshaft is analyzed bgy the transfer matrix method(TMM). The crankshaft has been modeled by 38 lumped mass and stiffness elements. The dynamic patameters of each lumped element are provided by Finite Element Method(FEM). The responses of the crankshaft from TMM are fed back as loading conditions to the Finite Element model to obtain dynamic stresses for critical areas of the crankshaft.

• 한국재료학회지
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• 제15권8호
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• pp.521-527
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• 2005

Surface modification of polypropylene hollow fiber membranes was peformed in order to develop blood-compatible biomaterials for use in the blood contacting and oxygenation membranes of a lung-assist device(LAD). Blood compatibility was determined by using anticoagulation blood and evaluating formation of blood clots on their surfaces as well as activation of plasma coagulation cascade, platelet adhesion, and aggregation. It was verified that the number of platelets on the silicone coated fibers was significantly lower than those on polypropylene. It was also found that the polypropylene hollow fiber membranes using plasma treatment exhibited suppression of complement activation in blood compatibility test.

• 한국인쇄학회지
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• 제23권2호
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• pp.93-101
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• 2005

The measured plasma temperature of Ar hollow cathode discharge for several metal cathodes are about $620\;{\sim}\;780K$ at discharge current of $7\;{\sim}\;10mA$. The optogalvanic signals were measured using hollow cathode discharge tube with argon as buffer gas at change of discharge currents. A change of ionization rate due to electron collision causes an increase or decrease of the electric conductivity. This change in electric conductivity generates the optogalvanic signal. We conclude that optogalvanic signal has close relation with the lowest metastable atoms density at low current.