• 태양에너지
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• 제18권2호
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• pp.115-121
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• 1998

본 연구에서는 캐비티 상부에 작은 틈새를 두고 여기에 구동류를 흐르게 함으로써 캐비티 내부유동 특성을 주유동 방향에 대하여 고찰하였고 채택된 레이놀즈수에 따른 순간속도벡터와 시간평균 속도분포, 그리고 운동에너지를 구하였다. 또한 바닥면에서 공급되는 열유속의 변화에 따른 내부 유동장의 변화를 고려하여 캐비티 내부의 유동특성도 체계적으로 규명하였다. 캐비티 내부의 유동형태는 전체적으로 강제와류와 유사한 속도분포가 지배적이었다. 또한 바닥면이 가열될 경우에 열유속이 증가할수록 자연대류의 영향이 크게 나타났으며 발열량의 증가에 따른 부력의 영향이 크게 나타났다.

• Current Optics and Photonics
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• 제1권6호
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• pp.631-636
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• 2017

We firstly develop a straightforward method to generate full $Poincar{\acute{e}}$ beams with any polarization geometry over an arbitrary order $Poincar{\acute{e}}$ sphere. We implement this by coaxial superposition of two orthogonal circular polarized beams with alternative topological charges with the help of a Mach-Zehnder interferometer. Secondly we find the existence of singularity points. And the inner relationship between their characteristics and the order of $Poincar{\acute{e}}$ spheres is also studied. In summary, this work provides a convenient and effective way to generate vector beams and to control their polarization states.

• 한국안전학회지
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• 제15권1호
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• pp.36-42
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• 2000

An experimental study was carried out to investigate the effects of inclined angles of channel on thermal stability of electronic components. In this study, it is focused on the natural convection heat transfer from an inclined parallel channel with discrete protruding heat sources. The material used for the inclined parallel channel was epoxy-resin, while air as the cooling fluid. Heat transfer phenomena for inclined angles of $\psi$=$15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$ and for the range of $9.52{\times}10^5/ were analyzed. The thermal fields in the channel were visualized by Mach-Zehnder interferometer. Also, local temperatures were measured by thermocouples along the channel wall and heat sources surface. As a result, for the range of $4.29{\times} 10^5/, a useful correlation of mean Nusselt number was proposed as a function of modified channel Rayleigh number.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1936-1938
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• 2002

A tunable fiber laser and the Quadrature Sampling technique are used to construct highly sensitive fiber-optic distributive Bragg grating strain sensor system. By using a wavelength-modulated fiber laser, the variations of strain-dependent Bragg wavelengths are transformed into the variations of time-domain reflection profiles. The locations of profile peaks that correspond to the applied strains are demodulated using a precise wavelength encoder that uses a fiber-optic Mach-Zehnder interferometer and Quadrature Sampling technique. With the extremely high sensitive optical encoder, we could obtain not only high sensitivity, but also very linear responses that was impossible with the conventional techniques. This paper is attempted to report the theoretical and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1041-1043
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• 1999

In this work, a possible new PD detection technique, based on the electro-optic effect, has been proposed. A proto-type probe sensor for detection partial discharge is made by $LiNbO_3$ Pockels cell, diachroic sheet polarizer and right-angle prism. The Mach-Zehnder interferometer system is proposed by using this sensor and this system is applied to detecting high electric field. we show the characteristic of the proto-type probe sensor and the design of a proposed probe type sensor.

• 한국광학회지
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• 제4권3호
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• pp.354-358
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• 1993

지그재그 슬랩 레이저의 글라스 내부 온도분포를 마하-젠더 간섭계로 측정하였다. 슬랩 레이저글라스의 파괴 원인은 슬랩글라스의 표면과 중심부의 온도차로 이 온도차 ${\Delta}T_0$가 $110^{\circ}C$, $62^{\circ}C$에서 두 장의 레이저글라스가 파괴되었다. 고평균출력 글라스레이저를 설계하는데 있어서 안전 작동을 이하여 슬랩글라스 표면과 중심부의 온도차 ${\Delta}T_0$가 $50^{\circ}C$를 넘지 않도록 해야한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권10호
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• pp.481-486
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• 2003

It is well known that a discharge in oil is the source of various physical phenomena. Ultrasonic-wave detection is a useful method to the diagnosis of the transformer-insulation condition. Conventionally, ultrasonic waves are detected by Piezo-electric transducer, and we use optical method that has many advantages. In this paper, we constructed a Mach-Zehnder interferometer with optical fiber and investigated the principle of operation. Test arrangement is based on the needle-plane electrode system in oil and applied AC high voltage. Ultrasonic waves were detected and analyzed with wavelet transform.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.513-515
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• 2000

In this paper, new Partial Discharge (PD) detection technique using Pockels-cell was proposed. For this purpose, PD was generated from needle-plane electrode in air and detected by optical measuring system using Pockets cell, based on Mach-Zehnder interferometer, consisting of He-Ne laser, single mode optical fiber, 50/50 beam splitter and photo detector. We show the characteristic of the proto-type sensor for the corona discharge.

• 설비공학논문집
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• 제2권4호
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• pp.257-267
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• 1990

A numerical and experimental investigation has been carried out to understand a characteristic of natural convection within a horizontal non-circular annulus. A finite-difference method has been used to solve the governing equations numerically. The effect of Rayleigh number. Prandtl number, aspect ratio and diameter ratio is studied analytically. The ranges of the parameters studied herein are Rayleigh number from $10^3$ to $2{\times}10^4$, Prandtl number from 0.1 to 10, aspect ratio from 0.25 to 1.5 and diameter ratio from 1.5 to 9.0. A Mach-Zehnder interferometer is used to obtain isothermal fringes for a diameter ratio Do/Di=2.6 and aspect ratio H/L=0.75 experimentally. A comparison between the experimental and numerical results under similar conditions shows good agreement.

• 전자공학회논문지S
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• 제34S권8호
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• pp.20-26
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• 1997

In this paper, we propose a tunable drop/pass filter in the form of composed of Mach-Zehnder interferometer, to which a fiber grating and two PZTs are attached. The proposed drop/pass filter drops a part of signal power at a specific wavelength and pass the remnant of the signal to the next node in WDM network. Our simulation results show that the optical feedback is less than 2% and the drop to pass ratio can be made bigger than 10% if the phase difference between the two arms is within .+-.0.2.pi. from (2m+1).pi.. Also, the output powers at drop prot and pass port are measured to be maximum at the phase difference of .pi./2 and .pi., respectively, as expected.