• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.106-109
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• 2007

The spray plume characteristics of liquid water jet injected into subsonic cross-flow at 42 m/s were experimentally investigated. Nozzle has a 1.0 m diameter and L/D=5. Droplet sizes, velocities, volume flux were measured at each downstream area of the injector exit using phase Doppler particle anemometry. Measuring probe position is moved with 3-way transversing machine. Experimental results indicate that SMD is varied from 75 to $120{\mu}m$ distribution and it is uncertain layer structure. SMD peaks at the top of the spray plume. This phenomenon is related to the momentum exchange between column waves and cross-flow stream. Droplet vector velocities were varied from 11.5 to 33 m/s. A higher-velocity region can be identified in down edge region at Z/D : 40, 70 and 100. Lower-velocity region were observed on bottom position of the spray plume. Volume flux is a criterion to the droplet concentration. All volume flux distribution has a same structure that continuously decreases from the center region to the edge of the plume. Z/D : 20 is spatially less concentrated than in Z/D : 100.

• Journal of the Korean Ceramic Society
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• v.16 no.4
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• pp.213-224
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• 1979

The present work was undertaken: (1) to determine if CaO-partially stabilized $ZrO_2$ prepared by Hot Petroleum Drying Method would show better ionic conductor as an oxygen sensor in molten metals than that prepared by Oxide Wet Mixing Method and than CaO-fully stabilized $ZrO_2$, and (2) to understand the nature of conduction mechanism of CaO-partially stabilized $ZrO_2$ by a comparison of measured electrical conductivity data with theory on defect structure of pure monoclinic $ZrO_2$ and fully stabilized cubic $ZrO_2$. The DC electrical conductivity was measured by 3-probe technique and the AC electrical conductivity by 2-probe technique as a function of temperature in the range 973-1373 K and oxygen partial pressure in the range 10-1-10-25Mpa. The results of the experiments were as follows: 1. CaO-partially stabilized $ZrO_2$ prepared by Hot petroleum Drying Method showed at T=1094-1285 K and $Po_2$=10-7-10-25 MPa a nearly ionic conduction with 4 times higher conductivity than that prepared by Oxide Wet Mixing Method. 2. High-oxygen pressure conductivity tends toward a Po_2^{+1/5}-Po_2^{+1/6}$dependence. An analysis of possible defect structures suggests that CaO-partially stabilized $ZrO_2$ has an anti-Frenkel defect in which singly or doubly ionized oxygen interstitials and defect electrons predominate at T=1094-1285 K and $Po_2$=10-1-10-7MPa. 3. The activation energy for pure electron hole-conduction and ionic conduction of CaO-partially stabilized $ZrO_2$ was found to be 130 KJ/mol at T=973-1373 K, $Po_2$=2, 127 10-2 MPa(air) and 153KJ/mol at T=1094-1285 K respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.449-449
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• 2013

최근 반도체 소자의 집적회로는 점점 복잡해지고 있는 반면, 소자의 크기는 작아지고 있으며 그로 인해 패드의 크기가 작아지고 패드사이의 간격 또한 협소해지고 있다. 따라서 웨이퍼 단계에서 제조된 집적회로의 불량여부를 판단하기위한 검사 장비인 프로브카드(Probe Card)의 높은 집적도가 요구되고 있다. 하지만 기존의 MEMS 공법으로 제작되는 프로브 빔은 복잡한 제조 공정과 높은 생산비용, 낮은 집적도의 문제점을 가지고 있다. 본 연구에서는 이러한 문제점을 해결하기 위하여 간단한 제조 공정과 낮은 생산비용, 높은 집적도를 가지는 프로브 빔을 개발하기 위하여 절연절단 방식으로 BeCu (Beryllium-Copper) 프로브 빔을 제작하였다. 낮은 소비 전력으로 우수한 프로브 빔 어레이를 제작하기 위해서 가장 고려해야할 대상은 프로브 빔의 재료와 구조(형상)이다. 절연전단 방식으로 프로브 빔을 형성할 때 요구되는 Fusing current는 프로브 빔의 구조(형상)에 크게 영향을 받는다. 낮은 Fusing current는 소비 전력을 줄여주고, 절연절단으로 형성되는 프로브 빔의 단면(끝)을 날카롭게 하여 프로브 빔과 집적회로의 패드 간의 접촉 저항을 감소시킨다. 프로브 빔의 제작은 BeCu 박판을 빔 형태로 식각하여 제작하였으며, 실리콘 비아 홀(Via hole) 구조의 기판위에 정렬하여 soldering 공정을 통해 실리콘 기판과 BeCu 박판을 접합시켰다. 접합된 프로브 빔의 끝부분을 들어 올린 상태로 전류를 인가하여 stress free 상태로 만들어 내부 응력을 제거하였으며, BeCu 박판에 fusing current를 인가하여 BeCu 박판 프레임으로부터 제거를 하였다. 제작된 프로브 빔의 길이는 1.7 mm, 폭은 $50{\mu}m$, 두께는 $15{\mu}m$, 절단부의 단면적은 1$50{\mu}m^2$로 제작되었다. 그리고 프로브 빔의 절단부의 길이는 $50{\mu}m$ 부터 $90{\mu}m$까지 $10{\mu}m$ 증가시켜 제작되었다. 이후에 절연절단 공정에 요구되는 Fusing current를 측정하였고, 절연절단 후의 절단면의 형상을 SEM (Scanning Electron Microscope)장비를 통하여 확인하였다. 절단부의 길이가 $50{\mu}m$일 때 5.98A의 fusing current를 얻었으며, 절연절단 후 절단부 상태 또한 가장 우수했다. 본 연구에서 제안된 프로브 빔 제작 방법은 프로브카드 및 테스트 소켓(Test socket) 생산에 응용이 가능하리라 기대한다.

• Economic and Environmental Geology
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• v.9 no.3
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• pp.135-141
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• 1976

The gamma-gamma logging method appplying in geophysical research are presented in this paper_ The logging probe assembly was designed which permits changing the source-to-detector spacing while conditions of proceeding ${\gamma}-{\gamma}$ logging, which a collimated gamma ray source ($^{60}Co$, 0.5mCi and/or 2 mCi) is separated from the scintillation detector as shown in Fig. 2 and 3, size is 6.0 cm in diameter and 120.0 cm in long and the exposed parts are made of stainless steel pipe. The results is confirmed by the experiment performed mainly in granite rock where a slightly constant shape was obtained but sometimes was shown sharpness shape for the measured scattered gamma-ray intensity. Consequently, the experimental results are obtained an adequate intensity of scattered gamma-rays and favourable response to density change, and also very closely correspond to between core samples of the test boring and to used this method of ${\gamma}-{\gamma}$ logging in the test bore-hole of the strata.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1121-1136
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• 2002

The flow characteristics of film coolant issuing into turbulent boundary layer developing on a convex surface have been investigated by means of flow visualization and three-dimensional velocity measurement. The Schlieren optical system with a spark light source was adopted to visualize the jet trajectory injected at 35° and 90° inclination angles. A five-hole directional pressure probe was used to measure three-dimensional mean velocity components at the injection angle of 35°. Flow visualization shows that at the 90° injection, the jet flow is greatly changed near the jet exit due to strong interaction with the crossflow. On the other hand, the balance between radial pressure gradient and centrifugal force plays an important role to govern the jet flow at the 35° injection. The velocity measurement shows that at a velocity ratio of 0.5, the curvature stabilizes downstream flow, which results in weakening of the bound vortex structure. However, the injectant flow is separated from the convex wall gradually, and the bound vortex maintains its structure far downstream at a velocity ratio of 1.98 with two pairs of counter rotating vortices.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.784-795
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• 1995

This paper represents the results of the experiments of the three-dimensional flow and the aerodynamic loss caused by the three-dimensional flow within the plane bucket blades. To research the secondary flow and the aerodynamic loss, the large-scale plane bucket blade of lst-stage in the low pressure steam turbine is made of FRP. The detailed investigation of the secondary flow and the aerodynamic loss using 5-hole pressure probe within turbine cascade has been carried out in the low speed wind tunnel. The limiting streamlines of the suction and endwall surface have been visualized by the oil film method. The flow visualization of the secondary flow has been performed by the laser light sheet technique and image processing system. By using the method mentioned above, it is possible to observe the evolution of the pitchwise mass-averaged flow deviation angle and total pressure loss coefficient, the secondary flow, and the aerodynamic loss through the cascade.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.575-581
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• 2007

As current and future automobile emission regulations become more stringent, the research on flow distribution for an exhaust manifold and close-coupled catalyst(CCC) has become an interesting and remarkable subjects. The design of a CCC and exhaust manifold is a formidable task due to the complexity of the flow distribution caused by the pulsating flows from piston motion and engine combustion. Transient flow at the exhaust manifold can be analyzed with various computational fluid dynamics(CFD) tools. However, the results of such simulations must be verified with appropriate experimental data from real engine operating condition. In this study, an experimental approach was performed to investigate the flow distribution of exhaust gases for conventional cast types and stainless steel bending types of a four-cylinder engine. The pressure distribution of each exhaust sub-component was measured using a simulated dynamic flow bench and five-hole pitot probe. Moreover, using the results of the pitot tube measurement at the exit of the CCC, the flow distribution for two types of manifolds(cast type and bending type) was compared in terms of flow uniformity. Based on these experimental techniques, this study can be highly applicable to the design and optimization of exhaust for the better use of catalytic converters to meet the PZEV emission regulation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.9
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• pp.1-11
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• 2022

Recently, there has been continuous technological development in the semiconductor industry, and semiconductor manufacturing technologies are being advanced and highly integrated. For this reason, ceramic material having excellent heat resistance, wear resistance, and conductivity are used as components in semiconductor manufacturing. Among them, the probe card's space transformer is used as ceramic material to prevent electronic signal noise during the electrical die sorting of semiconductor function testing. However, implementing a bulk-type space transformer with a thickness of 5.6 mm or more is challenging, and thus it is produced in a structure with a stacked ceramic film. The stacked space transformer has low productivity because it is difficult to ensure hole clogging and a precise shape. In this research, an ultrasonic horn is designed to manufacture a bulk-type ceramic space transformer through ultrasonic drilling. Vibration characteristics were analyzed according to the ultrasonic horn, and the natural frequency was measured.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.46-52
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• 2008

The instrumentation was studied in order to measure aerodynamic performance and efficiency of a compressor as a component of a 5MW-class gas turbine for power generation. In case of an axial compressor, the distributions of static pressure on a casing can be obtained by averaging at each stage and those of total pressure and temperature in the flow field of the compressor can be measured with a Kiel temperature probe. In case of a centrifugal compressor, the static pressures at the hub and the tip, respectively, of an impeller exit are considerably different, so the pressures need to be measured at both positions and thereafter averaged. The distributions of static pressures in a diffuser and a deswirler are measured at ten positions along five streamlines in one pitch. In addition the flow field can be measured in detail by 5-hole Pitot tube in order to analyze the flow characteristics of the core flow region and wake region and the rotor-stator interaction of the compressor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.109-117
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• 2002

An off-surface flow visualization experiments have been performed to investigate the flow field over a delta wing with the leading edge extension(LEX). The model is a flat wing with $65^{\circ}$ sweepback angle. The free stream velocity is 6.2 m/s, which corresponds to Reynolds number of $4.4\times10^5$ based on the wing root chord. The angle of attack and sideslip angle range from $16^{\circ}\sim28^{\circ}$ and $0^{\circ}\sim-15^{\circ}$, respectively. The visualization technique of using the micro water-droplet and the laser beam sheet enabled to observe the vortical flow structures, which can not be obtained by 5-hole probe measurements. With sideslip angle, the interaction and breakdown of the LEX and wing vortices was promoted in the windward side, whereas, it was suppressed in the leeward side.