• Current Optics and Photonics
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• v.4 no.1
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• pp.9-15
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• 2020

Fresnel zone plates have been widely used in many applications, such as x-ray telescopes, microfluorescence, and microimaging. To obtain an x-ray Fresnel zone plate, many fabrication methods, such as electron-beam etching, ion-beam etching and chemical etching, have been developed. Fresnel zone plates fabricated by these methods will inevitably lead to some nonideal factors, which have an impact on the focusing characteristics of the zone plate. In this paper, the influences of these nonideal factors on the focusing characteristics of the zone plate are studied systematically, by numerical simulations based on scalar diffraction theory. The influence of the thickness of a Fresnel zone plate on the absolute focusing efficiency is calculated for a given incident x-ray's wavelength. The diffraction efficiency and size of the focal spot are calculated for different incline angles of the groove. The simulations of zone plates without struts, with regular struts, and with random struts are carried out, to study the effects of struts on the focusing characteristics of a zone plate. When a Fresnel zone plate is used to focus an ultrashort x-ray pulse, the effect of zone-plate structure on the final pulse duration is also discussed.

• Journal of the Korean Society of Radiology
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• v.4 no.3
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• pp.27-31
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• 2010

Spatial resolution is determined by the performance of x-ray optics used in the x-ray imaging system. A zone plate was designed for obtaining a high spatial resolution image at x-ray energy of 8.5keV. A spatial resolution of 80 nm was estimated by the ray tracing when an x-ray tube of tungsten targe was used instead of synchrotron radiation. The designed zone plate of outermost zone width of 40nm was successfully fabricated by the electron-beam lithography.

• Laser Solutions
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• v.14 no.2
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• pp.13-16
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• 2011

We fabricated the Fresnel zone plate using femtosecond laser lithography-assisted micro-machining, which is a combined process of nonlinear lithography and wet etching. We investigated the focusing properties by launching a 632.8nm wavelength He-Ne laser beam into the zone plate. The spot size of the primary focal point was $27{\mu}m$ and the intensity of focal point was 0.565W/$cm^2$.

• Current Optics and Photonics
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• v.6 no.1
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• pp.44-50
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• 2022

An off-axis zone plate is able to focus on a single order while neglecting the zeroth order in a visible imaging system. This allows one to enhance the contrast quality in diffractive images, which is the major advantage of this type of zone plate. However, most previous reflection zone plates are used in focusing X-rays with a small grazing incident angle and are intricately designed with the use of a local grating period. In this study, we suggest the design of an off-axis elliptical zone plate (EZP) that is used to focus a monochromatic light beam with separation between the first and unfocused orders under a large grazing incident angle of 45°. An assumption using the total grating period, which depends on the average and constant grating period, is proposed to calculate the desired distance between the first and zeroth order and to simplify the construction of a novel model off-center EZP. Four diffractive optical elements (DOEs) with different parameters were subsequently fabricated by direct laser lithography and then verified using a performance evaluation system to compare the results from the assumption with the experimental results.

• Current Optics and Photonics
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• v.3 no.4
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• pp.285-291
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• 2019

We have studied the behavior of light in the intermediate regime between a single nanoslit and an infinite nanoslit array. We first calculated the optical characteristics of a small number of nanoslits using finite element numerical analysis. The phase variance of the proposed nanoslit model shows a gradual phase shift between a single nanoslit and ideal nanoslit array, which stabilizes before the total array length becomes ${\sim}0.5{\lambda}$. Next, we designed a transmission-enhanced Fresnel zone plate by applying the phase characteristics from the small-number nanoslit model. The virtual-point-source method suggests that the proposed Fresnel zone plate with phase-invariant nanoslits achieves 2.34x higher transmission efficiency than a conventional Fresnel zone plate. Our report describes the intermediate behaviors of a nanoslit array, which could also benefit subwavelength metallic structure research of metasurfaces.

• Korean Journal of Food Science and Technology
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• v.2 no.1
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• pp.67-71
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• 1970

The amylase was0 incubated in a 9mm hole on the starch agar gel plate bored with a cork borer. When 0.1N-iodine solution sprayed on the plate, the formed uncolored zone were observed. An activity of amylase has been determined by measurement of diameter of the uncolored zone. We named this method 'cork borer method'. When amylase was incubated on the starch agar gel plate, the following points were obtained. 1) The optimum pH for the formation of the zone in case of amylases(Biotex, Spitase) which produced by Bacillus is neutrality and alkali, while that for Glucoamylase, Biodiase, and Mucorrennin which produced by Rhizopus and Mucor is from 5 to 7. 2) The diameter of the zone was increased by the incubation time and amylase activity. 3) The zone was easily formed at low level of starch concentration and was formed much bigger than at $50^{\circ}C\;than\;at\;10^{\circ}C$. From the above results, after malting the starch agar gel plate, keeping constant concentration of the starch, the measurement of amylase activity is in efficiency upon the constant reaction time and temperature.

• Korean Journal of Optics and Photonics
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• v.8 no.1
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• pp.19-25
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• 1997

Holographic zone plate (HZP) is fabricated by interfering a plane wave and a spherical wave in a dichromated gelatin (DCG) film obtained from Agfa 8E75HD plates. We have developed a simple theory for HZP considering optical nonlinearity of DCG material. Analysis of our theory for HZP shows that it has infinite focal points at distances f,f/2, f/3,,…. In experiment, we observed the corresponding focal points of up to f/6 when illuminating HZP by a plane wave. It is also shown that the beam profile around the first focal point measured by using a knife-edge scanning method has a Gaussian shape.

• Computers and Concrete
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• v.24 no.5
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• pp.423-436
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• 2019

Design equations to evaluate the bursting force in a post-tensioned anchorage zone have been introduced in many design codes, and one equation in AASHTO LRFD is widely used. However, this equation may not determine the bursting force exactly because it was designed on the basis of two-dimensional numerical analyses without considering various design parameters such as the duct hole and shape of the bearing plate. To improve the design equation, modification of the AASHTO LRFD design equation was considered. The behavior of the anchorage zone was investigated using three-dimensional linear elastic finite element analysis with design parameters such as bearing plate size and diameter of sheath hole. Upon the suggestion of a modified design equation for evaluating the bursting force in an anchorage block with a rectangular anchorage plate (Kim and Kwak 2018), additional influences of design parameters that could affect the evaluation of bursting force were investigated. An improved equation was introduced for determining the bursting force in an anchorage block with a circular anchorage plate, using the same procedure introduced in the design equation for an anchorage block with a rectangular anchorage plate. The validity of the introduced design equation was confirmed by comparison with AASHTO LRFD.

• The Korean Journal of Food And Nutrition
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• v.34 no.6
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• pp.568-575
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• 2021

The purpose of this study was to investigate the effects of extract mixture of C. wilfordii and P. umbrosa (IPLUS-CWPU) on bone growth in 4-week old young male SD rats. To confirm the effect of IPLUS-CWPU, we measured the length of bone growth plate, the ratio of proliferative zone to the length of growth plate and the expression level of insulin-like growth factor, IGF-1. The IPLUS-CWPU treatment shows a significant increase of tibial and femoral growth plate and the ratio of proliferative zone in growth plate. Especially, the length increased by 13.9% and 25.3% in the tibia and femur, respectively, in the high-dose group compared to the normal group. Moreover, the expression of IGF-1 gene in liver was upregulated in IPLUS-CWPU treated groups. These results indicated that IPLUS-CWPU administration could increase the proliferative zone of bone growth plate in early developmental stage by upregulation of IGF-1 gene.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.2
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• pp.39-50
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• 1984

The plane bending corrosion fatigue test was performed on the welded zone between SM58 steel plate and SM41 steel plate jointed with submerged arc welding in the air and in the natural sea water with various conditions. The main results obtained from the test are summarized as follows: 1) The welded zone of the steel plates has the lowest impact strength and the highest electrode potential, but the hardness was mediate of SM58 base and SM41 base. 2) The cathodic protection of the welded zone was also effective for the plane bending corrosion fatigue, and the optimum protection potential of the welded zone was -1,000 mV SCE. 3) The corrosion fatigue strength under the various stress conditions of the steel plate could be estimated and also the require safety factors on the design could be obtained from the plane bending fatigue limit diagram.