• Current Optics and Photonics
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• 제4권1호
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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.

• 한국방사선학회논문지
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• 제4권3호
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• pp.27-31
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• 2010

엑스선 영상의 공간분해능은 영상획득 장치에 사용되는 광학소자의 성능에 의해 결정된다. 8.5keV에서 높은 공간분해능 달성이 가능한 존 플레이트를 설계하였다. 방사광을 이용하는 대신 엑스선 튜브를 사용하는 영상시스템에서는 80nm의 공간분해능을 달성할 수 있음을 광선추적 기법을 이용하여 예측하였다. 전자빔 석판인쇄술을 이용하여 최외곽 폭 40nm를 갖는 존 플레이트가 제작하였다.

• 한국레이저가공학회지
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• 제14권2호
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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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• 제6권1호
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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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• 제3권4호
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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.

• 한국식품과학회지
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• 제2권1호
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• pp.67-71
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• 1970

본 실험(本 實驗)에서는, amylase 활성(活性)을 측정(測定)하기 위하여 starch-agar-gel-plate를 만들어 cork borer로써 9mm의 구멍을 뚫고, 각(各) 농도(濃度)의 효소(酵素)를 주입(注入)하여 일정(一定)한 온도(溫度)에서 일정(一定)한 시간(時間)동만 반응(反應)시킨 후, 0.1N-iodine액(液)으로 분해(分解)하지 않은 starch를 착색시켜, 착색안된 무착색(無着色) zone의 직경을 측정(測定)해서 비교 검토한 것으로 서 이 방법(方法)을 "cork borrer method"라고 칭하였다. starch-agar-gel-plate 상(上)에서의 무착색(無着色) zone 형성(形成)의 최적(最適) pH는, Bacillus 균(菌)이 생산(生産)하는 amylase인 biotex, spitase 등은 중성(中性) 내지 알카리성(性)에서, 사상균이 생산(生産)하는 효소인 mucor-rennin, gluco-amylase, biodiase 등에 있어서는 pH $5{\sim}7$의 범위이다. 무착색(無着色) zone 형성(形成)직경은 전분농도(濃度)가 적을수록 유리하고, 반응시간(反應時間)이 길수록, amylase activity가 강할수록 커진다. 한편 반응온도(反應溫度)에 의한 영향은 $10^{\circ}C$보다 $50^{\circ}C$에서 무착색(無着色) zone이 크게 형성(形成)된다. 따라서 starch 온도(溫度) 및 pH가 일정(一定)한 starch-agar-gel-plate를 만들고, 반응시간(反應時間) 반응온도(反應溫度) 등을 일정하게 하여주면 amylase activity 를 능률있게 측정(測定)할 수 있다. 끝으로 본 연구(本 硏究)를 위하여 연구비(硏究費)를 지급(支給)하여주신 연합재단(聯合財團)과 대학원장 이길상박사(大學院長 李吉相博士), 또 효소(酵素)를 제공하여 주신 삼중효소공업주식회사(三中酵素工業株式會社)의 김동진사장(金東振社長). 천야제약주식회사(天野製藥株式會社)(일본(日本)) 등의 여러분께 진심으로 감사드립니다.

• 한국광학회지
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• 제8권1호
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• pp.19-25
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• 1997

Agfa 8E75HD 사진건판에서 얻은 dichromated gelatin(DCG) 박막에 구면파와 평면파를 간섭시켜 holographic zone plate(HZP)를 만들었다. DCG박막의 비서형적인 광학특성들을 고려하여 HZP의 이론식을 유도하였다. 이 이론식에 의한 HZP의 초점거리를 거리는 f. f/2, f/3, f/4, ... 였으며, 실험적으로도 평면파를 입사하여 6개까지의 해당 초점들을 관측하였다. 칼날 주사 방법으로 측정한 첫 번째 재생 초점 근처에서의 빔의 모양은 Gaussian 분포를 가짐을 확인하였다.

• Computers and Concrete
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• 제24권5호
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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.

• 한국식품영양학회지
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• 제34권6호
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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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• 제8권2호
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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.