• 한국가시화정보학회지
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• 제18권1호
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• pp.38-43
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• 2020

This paper presents a new type of electrowetting driven tandem light deflector for high performance optical application. To steer an incident light, the proposed light deflector deforms the fluid interface using electrowetting actuation. The performance of the light deflector was experimentally verified by using a prototype of the proposed light deflector. Single and tandem light deflectors were separately prepared using microfabrication processes. The optical tests of the deflectors were conducted using a laser light. The proposed tandem light deflector obtained a 45° beam steering angle with a 5.3° deflection angle while a single light deflector was required for a 10.9° deflection angle to obtain the same beam steering angle. The proposed tandem light deflector with high optical capability can be applied to various optical applications from camera modules in mobile smart devices to advanced future optical systems.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1090-1095
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• 2008

Track geometry changes by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, which determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from the characteristics of measuring device. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolley. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is EM-120, measures versine with 10m of symmetrical chord length.

• 전자공학회논문지B
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• 제32B권6호
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• pp.909-921
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• 1995

The objective of this paper is to develop an algorithm for a real-time automatic fingerprint recognition system. The algorithm employs the Fast Fourier Transform (FFT) in determining the directions of ridges in fingerprint images, and utilizes statistical information in recognizing the fingerprints. The information used in fingerprint recognition is based on the dircetions along ridge curves and characteristic points such as core points and delta points. In order to find ridge directions, the algorithm applies the FFT to a small block of the size 8x8 pixels, and decides the directions by interpreting the resulted Fourier spectrum. By using the FFT, the algorithm does not require conventional preprocessing procedures such as smoothing, binarization, thinning, and restorationl. Finally, in matching two fingerprint images, the algorithm searches and compares two kinds of feature blocks, one as the blocks where the dircetions cannot be defined from the Fourier spectrum, and the other as the blocks where the changes of directions become abrupt. The proposed algorithm has been implemented on a SunSparc-2 workstation under the Open Window environment. In the experiment, the proposed algorithm has been applied to a set of fingerprint images obtained by a prism system. The result has shown that while the rate of Type II error - Incorrect recognition of two different fingerprints as the identical fingerprints - is held at 0.0%, the rate of Type I error - Incorrect recognition of two identical fingerprints as the different ones - is 2.2%.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.839-846
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• 2013

This paper describes a finite element model of the microstructure of dispersion type nuclear fuels, which can be used to determine the effective thermal conductivity of the fuels during irradiation. The model simulates a representative region of the fuel as a prism shaped unit cell made of brick elements. The elements within the unit cell are assigned material properties of either the fuel or the matrix depending on position, in such a way as to represent randomly distributed fuel particles with a size distribution similar to that of the as manufactured fuel. By applying an appropriate heat flux across the unit cell it is possible to determine the effective thermal conductivity of the unit cell as a function of the volume fraction of the fuel particles. The presence of a fuel/matrix interaction layer is simulated by the addition of a third set of material properties that are assigned to the finite elements that surround each fuel particle. In this way the effective thermal conductivity of the material may also be determined as a function of the volume fraction of the interaction layer. Work is on going to add fission gas bubbles in the fuel as a fourth phase to the model.

• 한국광학회지
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• 제18권1호
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• pp.8-13
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• 2007

본 논문에서는 반사형 포토폴리머의 투과형 기록구조에서의 광학 특성을 분석하고 전반사 홀로그램 기법이 적용된 반사형 포토폴리머를 이용하여 미세패턴을 기록하였다. 투과형 포토폴리머는 대칭형 입사구조에서 $40^{\circ}$ 일 때 최대 효율을 보였으나 반사형 포토폴리머는 $60^{\circ}{\sim}80^{\circ}$에서 90% 이상의 회절효율을 보였다. 미세패턴 기록에서 10배 및 100배로 확대하여 측정한 결과 선 패턴과 점 패턴 간격 모두 $1{\mu}m$ 까지 구분할 수 있었다.

• 암석학회지
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• 제7권1호
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• pp.53-68
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• 1998

거정 장석(주로 K-장석)반정을 다량 함유하는 변형된 청산 화강암에 대한 미구조 및 암석구조 연구를 통하여 연성전단변형 동안의 온도조건을 규명하고자 한다. K-장석에서 가장 중요한 미구조로는 미세킹크, 미세단열 그리고 코아 외부에 아입자 없는 코아-맨틀구조 등으로 인지된다. 밀메카이트와 플레임 퍼어사이트는 조각된 K-장석들의 입계에 고 변형량의 집중으로 그들 입계상에서 발달한다. 사장석에는 미세단열과 변형쌍정 그리고 킹크대가 우세하게 나타난다. 화성기원의 사장석 누대구조가 변형쌍정에 의해 중첩되는 미세조직은 저 변형암에서 종종 관찰된다. 연성전단변형 동안에 재결정된 석영에 대한 c-축 배열 형태는 주로 prism가 탁월한 미끄럼계로 작용하여 형성된 single girdle과 type II crossed girdle을 모여준다. 연성전단운동 동안에 형성된 이상과 같은 특징적인 미구조로부터 청산 화강암에서 연성전단변형은 녹염석-각섬석상 변성도($400-500^{\circ}C$)에서 발생한 것으로 해석된다. 청산화강암에 발달된 연성전단대는 고 변형대가 혈관상으로 나타나는 불연속 전단대와 S-C 압쇄구조면을 갖는 연속 전단대 그리고 일정한 폭의 균질엽리 영역을 보이는 균질 전단대로 형태 분류된다. 이들 연성전단대는 동일 변형단계에서 형성되었으며 이들 연성전단대의 형태 변화는 $400-500^{\circ}C$의 변형온도에서 변형량의 차이로부터 비롯된 것으로 해석된다.

• 센서학회지
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• 제26권1호
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• pp.28-34
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• 2017

An NIR grism Si optical area sensor spectrometer with in-band reference wavelength is designed and fabricated. It is composed of a transmission type diffraction grating (spatial density 300 line/mm), a rectangular N-BK7 prism (apex angle 30 degree), NIR filter(cutoff wavelength 720 nm), an imaging convex lens(focal length 50 mm F1.8) and an IR modified DSLR camera (Canon EOS40D) of Si optical area sensor ($3,888{\times}2,592$ pixels, pixel size $5.710{\mu}m$). "In-band reference wavelength function" is implemented using non-dispersive 0th diffraction order optical beam. The NIR grism spectrometer is tested in a laboratory using a halogen lamp and a Neon lamp. And the spectrometer is used in an astronomy field for obtaining the planet Jupiter NIR spectrum. In-band reference wavelength i.e. un-deviation wavelength is 846 nm, an wavelength resolution is 0.3027 nm/pixel, an wavelength resolving power is 2,794 and an wavelength range is 650~1,000 nm.

• 대한기계학회논문집B
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• 제22권1호
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• pp.12-24
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• 1998

The paper presents the mechanism of secondary flows and the associated total pressure losses occurring in turbine cascades with turning angle of about 127 and 77 degree. Velocity and pressure measurements are taken in seven traverse planes through the cascade passage using a prism type five hole probe. Oil-film flow visualization is also conducted on blade and endwall surfaces. The characteristics of the limiting streamlines show that the three dimensional separation is an important flow feature of endwall and blade surfaces. The larger turning results in much stronger contribution of the secondary flows to the loss developing mechanism. A large part of the endwall loss region at downstream pressure side is found to be very thin when compared to that of the cascade inlet and suction side endwall. Evolution of overall loss starts quite early within the cascade and the rate of the loss growth is much larger in the blade of large turning angle than in the blade of small turning angle.

• Computers and Concrete
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• 제17권1호
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• pp.129-140
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• 2016

Basalt is a type of volcanic rocks, grey to black in colour, contains less than 20% quartz, 10% feldspathoid, and at least 65% of the feldspar of its volume. Basalt is considered an igneous rock with fine grains due to the rapid cooling of lava. Basaltic rocks have been widely used as aggregate for various purposes. The study presented in this paper was carried out on basalts that are widespread in the Madeira Island of Portugal and that comprise the major source of local crushed rock aggregates. This paper discusses an experimental programme that was carried out to study the effects of basaltic aggregate on the compressive strength and modulus of elasticity of concrete. For this purpose, cylinder specimens with $150{\times}300mm$ dimensions and prism specimens with $150{\times}150{\times}375mm$ dimensions were cast. The experimental programme was carried out with several concrete compositions belonging to strength classes C20/25, C25/30, C30/37, C40/50 and C60/75. The Eurocode 2 indicates the modulus of elasticity should be 20% higher when the aggregates are of basaltic origin, however results showed significant differences and a correction is proposed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 2부
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• pp.99-104
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• 2011

Daylighting system is an alternative to the energy crisis and environment change. And it is possible improvement system of Architectural Space Environment. Accordingly, it is very useful system. Because Daylight Duct System of Daylighting System gives high performance for its price, distribution rate is very high. But Daylighting Duct System is hard to accurate control. Accordingly, it is difficult to maintain continuously Daylight Environment in Interior Spaces. Lighting Diffusion System has been developed that it is Applying the principle of Reflector and prism diffuser for maximize the efficiency of lighting of Daylight Duct Systems through this study. And then compare lighting performance of Existing System and new Lighting Diffusion System through producing a mock-up. Thus, this study was carried out for the purpose of verification for excellence. It is that installed Each Daylighting Duct System for performance evaluation in a laboratory of width 4m, length 10m, height 2.5m. And illuminance was measured at noon on winter solstice(December 22) under clean sky. The actual measurement result was in the following. Newly developed lighting Diffusion system was measured maximum illuminance 399, minimum illuminance 221, average illuminance 141. Synthetically, daylight factor, uniformity factor and illuminance distribution were improved more than existing system. As a result, it was confirmed that was improved lighting Environment in Interior Spaces.