• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.145-152
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• 2003

The objective of the present study is to develop methodology for the assesment of combustion stability of liquid rocket injectors. To simulate actual combustion occurring inside of a thrust chamber, a full-scale injector has been employed in the study, which burns gaseous oxygen and mixture of methane and propane. The main idea of the experiment is that the mixing mechanism is considered as a dominant factor significantly affecting combustion instability in a full-scale thrust chamber. Single & multi split triplet injectors have been used with an open-end cylindrical combustion chamber. The characteristics revealed by excited dynamic pressures in gaseous combustion show degrees of relative acoustic damping depending on operating conditions. Upon test results, the direct comparison between various types of injectors can be realized for the selection of the best design among prospective injectors.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.75-83
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• 2001

This paper presents the evaluation of combustion characteristics of sing-hole plasma jet ignitions in comparison with conventional spark ignition for variable of swirl velocity. Plasma jet plugs are three types according to ejecting directions : center of chamber, positive and negative swirl flow direction. Experiments are carried out for equivalent ratio 1.0 of LPG-air mixture in a constant volume cylindrical vessel. Not only the flame propagation is photographed at intervals, but the pressure variation in the combustion chamber is also recorded throughout the entire combustion process. The results show that the plasma jet ignitions and spark ignition enhance the overall combustion rate by increasing the swirl velocity. The dependence of the combustion rate swirl velocity leade to the conclusion that the placma jet plug, which ejects plasma jet to the cwnter of combustion chamber is the most desirable ignitor than other plugs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.579-579
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• 2013

We study on Argon metastable and 4p state neutral atom density in magnetized ICP Helicon plasmas by Laser Induced Fluorescence and plasma emission. The results show that metastable density is too low at the center of chamber due to significant neutral depletion. Otherwise, 4p state is high at the center of chamber because electron density is very high. Power and pressure dependence of metastable and 4p state neutral atom have been spatially measured in the radial direction of cylindrical chamber.

• 한국자동차공학회논문집
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• 제11권4호
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• pp.29-36
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• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of inhomogeneous charge methane-air mixture under several parameters. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer was used to investigate the effect of initial charge pressure, excess air ratio and ignition times on combustion pressure and combustion duration. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to beneath 0.05m/s gradually at 3 seconds. Second mixture is accompanied by an increase in the combustion rate, and that the higher the mass which is added in the second stage injection, the faster the burn rate.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.529-532
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• 2003

In this paper, the discharge characteristics of silent discharge chamber with 2mm and 3mm gap spacings were investigated. Dielectric of $Al_2O_3$ was embedded in the cylindrical type of discharge chamber. It was known that V-I and P-V characteristics depend strongly on the charge transportation characteristics, and in the low frequency silent discharge mode of operation, discharge voltage was always sustained to Vd, irrespective of applied voltage.

• 한국기계가공학회지
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• 제11권3호
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• pp.138-145
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• 2012

The material used in this study is dielectric and ferrite. Because of the unique characteristics of the material, it is easily exposed to external shocks and pressure, which cause damage to the product. However, after being processed under high-temperature environment repeatedly, the mechanical strength of the product is greatly increased due to the change of the electrical properties. In this paper, dielectric and bonded ferrite material was tested for the material properties. The equipment for this experiment was produced and tested to allow Cylindrical and Three-dimensional geometry of the product for the vacuum deposition. For Cylindrical shape of the product, in order to obtain the equivalent film thickness, the device is constructed in a vacuum chamber which gives arbitrary revolving and rotating capability. The electrical performance of the product is obtained through this process as well. However, as mentioned above, with repeating processes under high temperature and exposure to external environment, the product is easy to be broken. This experiment has enabled us to find out a stable condition to apply the communication of the RF high frequency to each of the core elements, such as Ferrite and Dielectric which is then used for the mechanical strength of the Raw material, hetero-junction material, Hetero-junction Ag Coating material and hetero-junction Ag Coating SiO2 Coating material respectively.

• Journal of Biosystems Engineering
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• 제37권2호
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• pp.113-121
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• 2012

Purpose: Particle separation in solution is one of important process in a unit operation as well as in an extract preparation for biosensors. Contrary to centrifuge-type of mesh-type filter, using an ultrasonic standing wave make the filtering process continuous and free from maintenance. It is needed to investigate the characteristics of particle movement in the ultrasonic standing wave field. Methods: Through the computer simulation the effects of major design and driving parameters on the alignment characteristics of particles were investigated, and a cylindrical chamber with up-stream flow type was devised using two circular-shape PZTs on both sides of the chamber, one for transmitting ultrasonic wave and the other for just reflecting it. Then, the system performance was experimentally investigated as well. Results: The speed of a particle to reach pressure-node plane increased as the acoustic pressure and size of particle increased. The maximum allowable up-stream flow rate could be calculated as well. As expected, exact numbers of pressure-node planes were well formed at specific locations according to the wavelength of ultrasonic wave. As the driving frequency of PZT got close to its resonance frequency, the bands of particles were observed clearer, which meant the particles were trapped into narrower space. Higher excitation voltages to the PZT produced a greater acoustic force with which to trap particles in the pressure-node planes, so that the particles gathered could move upwards without disturbing their alignments even at a higher inlet flow rate. Conclusions: This research showed the feasibility of particle separation in solution in the continuous way by an ultrasonic standing wave. Further study is needed to develop a device to collect or harvest those separated particles.

• 한국습지학회지
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• 제25권3호
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• pp.176-183
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• 2023

본 연구는 자유수면 아래 원통형 와류발생부에서 와류 수차 성능에 대한 블레이드 수가 미치는 영향을 이해하는 것이다. 동일한 블레이드 형상을 사용하여 상대 와류 수심비(y/h_v) 0.065 ~ 0.417 범위에 설치된 2개, 3개, 4개, 5개 및 6개의 블레이드로 마이크로 와류 수차의 성능을 실험하였다. 연구 결과로서 블레이드 수가 증가함에 따라 회전수, 전압, 전류 및 출력이 유속 0.7 m/s 이하일 때 상대 와류 수심비 0.065와 0.111 지점에서 증가한다. 5개 블레이드 수차의 평균 출력은 다른 블레이드 수보다 높게 나타난다. 오리피스 근처에 설치된 직경 130 mm인 4개의 블레이드 수차의 성능이 와류발생부에서 동일한 수의 직경 220 mm인 블레이드 수차보다 높다.

• 한국해양공학회지
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• 제33권3호
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• pp.272-279
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• 2019

In order to perform a pressure chamber experiment with a circular cylindrical pressure vessel, the dimensions of the cylinder need to be determined in the range of the maximum externally applied pressure of the chamber to create the collapse process. In this study, the collapse load values from published chamber test results, finite element analysis and the theory of thick cylinders were thoroughly compared in a aluminum cylinder. In order to investigate the effect of collapse load according to the ovality during manufacturing, nonlinear buckling analysis was performed and the collapse load according to ovality was compared. Based on the results, the dimensions of the steel cylinder were determined for the future chamber collapse test.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.435-435
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• 2010

A inclined slot-excited plasma source is newly designed and constructed for higher flux HNB(Hyperthermal Neutral Beam) generation. The present source is different from the vertical SLAN(SLot ANtenna) sources [1] in two aspects. One is that the slots are inclined, and the other is that the magnetic field is configured to a cusp type. These modifications are intended to make the source plasma operated in sub-milli-torr pressure regime and as thin as possible, both of which is to get higher HNB flux by decreasing the re-ionization rate of the reflected atoms from the neutralizer [2]. The plasma is generated in a quartz tube of internal diameter 170 mm enclosed in a aluminum application chamber of larger diameter 250 mm. The microwave power is fed to the plasma chamber by 8 inclined slots cut into the application chamber wall. The slots are coupled the chamber to a WR280 waveguide wound around it to form a ring resonator. In order to make two slots $\lambda_g/2$ apart in phase, the adjacent slots are rotated in opposite directions. The rotation angle of the slots are set to $60^{\circ}$ from the chamber axis. Between the quartz chamber and the aluminum cylindrical chamber 8 NdFeB magnets are equally spaced and fixed to form the cusp magnetic field confinement and ECR (Electron Cyclotron Resonance) field. In this presentation, the magnetic and electromagnetic simulations, and the measured plasma parameters are given for both the inclined and the vertical slot-excited plasma sources. We also discuss how the sources can be tailored to suit better-performing HNB sources.