• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.400-401
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• 2006

광-바이오센서로 이용하기 위해 광섬유 형태의 마흐-젠더 간섭계와 측면 연마된 광섬유를 결합한 구조를 제안하였고, 이를 제작 및 특성 평가하였다. 마흐-젠더 간섭계 구성은 1310nm와 1550nm 파장에서 광 파워 분기비가 50:50인 $2{\times}2$ 광커플러 2개를 제작하여 구성하였으며, 센서부로는 측면 연마한 광섬유를 이용하였다. 제작된 광섬유 형태의 마흐-젠더 간섭계 센서의 센서부 표면에 다양한 굴절률 용액을 이용하여 광학적 특성을 평가하였다.

• Journal of the Optical Society of Korea
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• v.9 no.4
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• pp.169-172
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• 2005

The phase sensitivity of the coincidence detection in one output port of a Mach-Zehnder interferometer is analysed for twin Fock state inputs. Firstly, the ideal detectors with quantum efficiency of unity are assumed for the detection of the output photons. The sensitivity is found out to be independent of the photon number of input light, which means that the Heisenberg limit cannot be reached in the coincidence detection even with ideal detectors. Secondly, the practical detectors with quantum efficiencies less than unity are discussed.

• Korean Journal of Optics and Photonics
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• v.1 no.2
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• pp.191-197
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• 1990

An experiment on the phase stability of injection-locked beam is done by using AlGaAs semiconductor lasers. The coherence of two beams from the master and slave lasers is measured by interference between the beams in the Twymann-Green interferometer. The phase change of the output beam of the slave laser as a function of the driving current is measured in the Mach-Zehnder interferometer consisted of the master and slave lasers and a value of 2.5radlmA is obtainccl.

• 한국가시화정보학회:학술대회논문집
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• 2006.12a
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• pp.145-148
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• 2006

In order to design a micro-thruster which controls the altitude of a space vehicle for a very long lifetime, the flow field should be analyzed considering the nozzle geometry and the difference between stagnation and environmental pressures and so on. This paper describes the axisymmetric non-reacted computational results which were carried out to understand the basic flow phenomena according to the high nozzle pressure ratio. The area ratio is about 56 and the diameter of a nozzle exit is about 0.46 inch. The Mach cell and waves are predicted well.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.109-112
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• 2002

The supersonic jet discharging from a petal nozzle is known to enhance mixing effect with the surrounding gas because it produces strong longitudinal vortices due to the velocity difference from both the major and minor axes of petal nozzle. In the present study, the supersonic free jet discharging from the petal nozzle is investigated experimentally. The nozzles used are 4, 6, and 8 lobed petal nozzles with a design Mach number of 1.7, and the flow fields are compared with a circular nozzle with the same design Mach number. The pitot impact pressures are measured using a fine pilot probe. The flow fields are visualized using a Schlieren optical method. The results show that the petal nozzle has more increased supersonic length compared with the circular jet.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.42-49
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• 2000

A computation using the mass-averaged implicit Wavier-Stokes equations has been applied to solve the flow fields of the supersonic jets normally injected into supersonic freestreams and several types of turbulence model has been employed to close the governing equations. The ratio of the freestream to injection flow total pressures has been varied to elucidate the major characteristics of the mixing flow of the two streams. The freestream Mach number has been varied to investigate some change in the injection flow field. The results show that the positions of the separation and reattachment, locating upstream and downstream of the injection hole respectively, are strongly dependent on the ratio of total pressures and the freestream Mach number.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.266-271
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• 2008

Generation mechanisms of pressure waves from the H-IIA launch vehicle are analyzed numerically. The Mach wave radiated downstream from wavy shearlayer of supersonic exhaust plume is revealed to be the dominant noise source. Reflecting from the constructions of the launch-pad, the Mach wave turns to propagate to the vehicles. It was also found that the fluctuating supersonic plume entering into the flame duct is the dominant noise source that appears in the flame duct. Then, the pressure wave propagates through the flame duct and is ejected outside to the vehicle.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.388-391
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• 2012

Intake start characteristics of a Mach 5 scramjet engine were investigated experimentally. Intake unstart was observed. The model-facility interaction or excessive internal contraction ratio were attributed to this unstart. Intake start was achieved by changing the model position to remove the model-facility interaction, and by modifying the cowl to give smaller contraction ratio.

• Journal of the Optical Society of Korea
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• v.7 no.2
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• pp.113-118
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• 2003

A two-photon interference experiment is presented in which an entangled pair of photons generated from a parametric down-conversion was incident on two input ports of a Mach-Zehnder interferometer. The experiment was carried out using two photon coincidence detection with two detectors at the two output ports of the interferometer. The measured coincidence counts exhibit an interference effect with visibility of 0.75 at simultaneous inputs and 0.38 at inputs with different arrival times according to the degree of photon number entanglement.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.222-227
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• 2015

We propose a new and potentially integrable scheme for the realization of an all-optical binary full adder employing two XOR gates, two AND gates, and one OR gate. The XOR gate is realized using a Mach-Zehnder interferometer (MZI) based on a semiconductor optical amplifier (SOA). The AND and OR gates are based on the nonlinear properties of a semiconductor optical amplifier. The proposed scheme is driven by two input data streams and a carry bit from the previous less-significant bit order position. In our proposed design, we achieve extinction ratios for Sum and Carry output signals of 10 dB and 12 dB respectively. Successful operation of the system is demonstrated at 10 Gb/s with return-to-zero modulated signals.