• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.153-156
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• 1999

In this paper, the inertance tube is modeled by the distributed impedance model. This model is verified by the analytical solutions for the long tube without the reservoir. In this model the distributed impedace effect of the inertance tube is included and mass flow rate and pressure distributions are calculated along the inertance tube for various inertance tube lengths. Mass flow rate at the inlet of the inertance tube is also calculated by this model and compared to the lumped impedance method. Mass flow rate by the distributed model shows quite different behaviors from the lumped model when the operating frequency is high and the length of the tube becomes large.

• 전기의세계
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• 제13권3호
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• pp.21-27
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• 1964

A method of triggering a series connected complementary transister flip-flop is described. Also measurements have been made for the operation region with respect to the input pulse variation. This circuit is compared with a Eccles-Jordan flip-flop when it used as a Nixie tube driver of a neon lamp driyer.

• 한국소음진동공학회논문집
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• 제24권5호
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• pp.399-406
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• 2014

Underwater acoustic materials are installed in order to reduce reflection, transmission and radiation of an underwater structure. The acoustic performance of the materials should be evaluated in accurately-controlled environment in terms of temperature and static pressure. In this paper, two pulse tubes, which are equipped with temperature and pressure controllers, are designed and developed to evaluate echo reduction(ER) and transmission loss(TL) of underwater acoustic materials. The procedures of the evaluation are suggested and the validation is carried out by comparing theoretical values to experimental results for a simple stainless steel specimen and free surface. In result, it is validated that developed pulse tubes are able to measure ER and TL with 2 dB tolerance.

• 설비공학논문집
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• 제19권3호
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• pp.220-227
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• 2007

Heat transfer and momentum transfer under conditions of both oscillating flow and oscillating pressure within pulse tubes show very different behavior from those for steady state conditions. The analytic solutions of axial velocity and temperature of the gas within pulse tubes were obtained by assuming that the variations in pressure and temperature were purely sinusoidal and small. The shear stress and the heat flux at the tube wall obtained from the solutions are expressed in terms of the cross-sectional averaged velocity, the difference between mean temperature and instantaneous cross-sectional averaged temperature and the difference between mean pressure and instantaneous pressure. It is shown that the complex shear factor, which has been applied to momentum transfer of incompressible oscillating flow, and the complex Nusselt number, which has been applied to either heat transfer with oscillating pressure only or heat transfer of incompressible oscillating flow, could also be used for momentum transfer and heat transfer subjected to both oscillating flow and oscillating pressure, respectively.

• Advances in aircraft and spacecraft science
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• 제10권3호
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• pp.203-222
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• 2023

The detonation combustion is a supersonic combustion process follows on shock wave oscillations in detonation tube. In this paper numerical studies are carried out combined effect of blockage ratio and spacing of obstacle on detonation wave propagation of hydrogen-air mixture in pulse detonation combustor. The deflagration to detonation transition of stoichiometric (ϕ=1)fuel-air mixture in channel has been analyzed for effect of blockage ratio (BR)=0.39, 0.51, 0.59, 0.71 with spacing of 2D and 3D. The reactive Navier-Stokes equation is used to solve the detonation wave propagation mechanism in Ansys Fluent platform. The result shows that fully developed detonation wave initiation regime is observed near smaller vortex generator ratio of BR=0.39 inside the combustor. The turbulent rate of reaction has also a great significance role for shock wave structure. However, vortices of rapid detonation wave are appears near thin boundary layer of each obstacle. Finally, detonation combustor demonstrates the superiority of pressure gain combustor with turbulent rate of reaction of 0.6 kg mol/m3 -s inside the detonation tube with obstacle spacing of 12 cm, this blockage enhanced the turbulence intensity and propulsive thrust. The successful detonation wave propagation speed is achieved in shortest possible time of 0.031s with a significance magnitude of 2349 m/s, which is higher than Chapman-Jouguet (C-J) velocity of 1848 m/s. Furthermore, stronger propulsive thrust force of 36.82 N is generated in pulse time of 0.031s.

• 센서학회지
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• 제22권6호
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• pp.439-443
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• 2013

A wireless optical fiber interferometer arterial pulse wave sensor system is developed for remote sensing. The wireless optical fiber sensor system consists of Zigbee communication modules and an optical fiber interferometer arterial pulse wave sensor. The optical fiber arterial pulse wave sensor is an in-line Michelson interferometer enclosed with steel reinforcement in a heat-shrinkable tube. The Zigbee communication modules are composed of an ATmega128L microprocessor and a CC2420 Zigbee chip. The arterial pulse waves detected by the optical fiber sensor were transmitted and received via the Zigbee communication modules. The experimental results show that the wireless optical fiber sensor system can be used for monitoring the arterial pulse waves remotely.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.115-117
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• 2004

Nd:YAG laser welding system was used to manufacture instrumented irradiation fuel. The optimal condition of zircaloy-4 seal tube is charge voltage 180V and pulse per energy 51. We got good welding result in charge voltage 400V, pulse width 7ms, pulse frequency 5 in zircaloy-4 endcap welding.

• 조명전기설비학회논문지
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• 제15권6호
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• pp.8-14
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• 2001

메탈핼라이드램프는 고효율, 고연색성이며 집광능력이 좋다. 그러나 메탈핼라이드 램프의 단점은 아크튜브내에서 음향공명현상이 발생되는 것으로 알려져 있다. 이러한 음향공명은 점등상태의 불안정과 기체의 심한 파동을 일으킨다. 심한 파동과 불안정한 점등으로 아크가 소멸되는 부위는 전압이 상승되고, 방전관내벽에 근접된 아크는 국부의 과열로 튜브를 금가게한다. 이 연구의 목적은 펄스스타트 메탈핼라이드램프 MH200[W]의 아크튜브내에서 음향공명을 감소시키는 것이다. 음향공명현상을 감소시키기 위하여 전자식안정기가 84.6[kHz]에서 94.2[kHz] 대역내에 있는 89[kHz]의 단독주파수인 정현고주파를 램프에 공급하기 위하여 설계되었다. 실험결과 고효율 펄스스타트 MH200[W] 램프의 방전관내에 음향공명 현상이 없었다.

• 대한기계학회논문집B
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• 제39권2호
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• pp.119-124
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• 2015

반도체 생산에 사용되는 액체용 극소 질량유량계측기의 새로운 설계 안에 대하여 수치해석적으로 연구하였다. 내경 0.3mm 정도인 원관 외부에 히터선을 일정 폭 권선하고, 히터로부터 일정거리 떨어진 후류에 온도계측용 써미스터선을 권선하는 형상이다. 히터에 단일펄스 가열을 하면 일정시간 경과 후 써미스터가 최고온도를 겪는다. 최고온도까지 걸리는 시간은 질량유량과 거의 반비례하며, 이를 이용하여 질량유량을 계측할 수 있다. 관벽을 통한 전도열전달과 액체유동에 의한 대류열전달이 복합적으로 작용하므로 관내유동의 평균속도와 관벽을 통한 최고온도의 이동속도는 큰 차이를 나타내며, 상호 비선형적인 특성을 보인다. 본 연구에서는 센서관의 내 외경, 히터의 권선폭 및 히터와 써미스터 사이의 거리를 설계변수로 고려하여 수치해석적으로 제안한 설계사항을 분석하였으며, 설계인자의 최적화에 대한 검토를 수행하였다.

• 대한설비공학회지:설비저널
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• 제21권2호
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• pp.75-87
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• 1992