• 한국연소학회지
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• 제7권2호
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• pp.62-68
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• 2002

To investigate statistics of flamelet in a turbulent premixed flame and to obtain components of their burning velocities in a vertical plane above a pipe-flow burner, the local motion of flamelets with respect to gas are measured by specially arranged diagnostics, composed of an electrostatic probe with four identical sensors and a two-color four-beam LDV system. With this technique, the three-dimensional local flame- front-velocity vector is measured by the electrostatic probe for the first time, and simultaneously the axial and radial components of the local gas-velocity vector in a vertical plane above the vertically oriented burner are measured by the LDV system. Two components of burning velocities of planar flamelets can be obtained from these results and are found to be distributed over different directions and to range in magnitude from nearly zero to a few times the planar, un strained adiabatic laminar burning velocity measured in the unburnt gas. It may be concluded from these results that turbulence exerts measurable influences on flamelets and causes at least some of them to exhibit increased burning velocity.

• 대한의용생체공학회:의공학회지
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• 제32권1호
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• pp.32-36
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• 2011

The insufflators in endoscopic surgery supply carbon dioxide to make the air-filled cavity in the abdomen. It contains many kinds of pneumatic and electronic parts and they are connected with the air tubes and electrical wires. The printed circuit boards (PCB) perform wiring, holding and cooling tasks in electronic systems. In this study, the PCB is used as the air channel for insufflators to decrease the cost, volume, and the malfunction according to aging of the device. Three layers of PCB made of FR4 are combined with prepreg as adhesive which has the internal airway channel according to the design. By mounting the pressure sensors and valves, the PCB based fluidic system is implemented. After calibration of flow sensor, the flow rate of the gas also can be measured. The climate test, temperature test, and biocompatibility test showed this idea can be used in insufflators for laparoscopic surgery.

• 한국전산유체공학회지
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• 제18권1호
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• pp.13-21
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• 2013

Cavitating flow is usually formed on the surface of a high speed underwater object. When a object moves near a free surface at very high speed, the cavity signature becomes one of the major factors to be overcome by sensors of military satellite. The present work was to study the free surface effect on the ventilated cavitation. The governing equations were Navier-Stokes equations based on a homogeneous mixture model. The multiphase flow solver used an implicit preconditioning method in the curvilinear coordinate system. The cavitation model used here was the one first presented by Merkle et al.(2006) and redeveloped by Park & Ha(2009). Computations considered the free surface effects were carried out with a NACA0012 hydrofoil and the corresponding results were compared with the experimental data to have a good agreement. Calculations were then performed considering the ventilated cavitation, including the effect of non-condensable gas under the free surface effects.

• 센서학회지
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• 제14권1호
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• pp.22-27
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• 2005

A thermoelectric flow sensor for small quantity of gas flow rate was fabricated using silicon wafer semiconductor process and bulk micromachining technology. Evanohm R alloy heater and chromel-constantan thermocouples were used as a generation heat unit and sensing parts, respectively. The heater and thermocouples are thermally isolated on the $Si_{3}N_{4}/SiO_{2}/Si_{3}N_{4}$ laminated membrane. The characteristics of this sensor were observed in the flow rate range from 0.2 slm to 1.0 slm and the heater power from 0.72 mW to 5.63 mW. The results showed that the sensitivities $(({\partial}({\Delta}V)/{\partial}(\dot{q}));{\;}{\Delta}V$ : voltage difference, $\dot{q}$ : flow rate) were increased in accordance with heater power rise and decreasing of flow rate.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.126-126
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• 2009

Noninvasive plasma diagnostic technique is introduced to analyze and characterize HICP (Helmholtz Inductively Coupled Plasma) source during the plasma etching process. The HICP reactor generates plasma mainly through RF source power at 13.56MHz RF power and RF bias power of 12.56MHz is applied to the cathode to independently control ion density and ion energy. For noninvasive sensors, the RF sensor and the OES (Optical emission spectroscopy) were employed since it is possible to obtain both physical and chemical properties of the reactor with plasma etching. The plasma impedance and optical spectra were observed while altering process parameters such as pressure, gas flow, source and bias power during the poly silicon etching process. In this experiment, we have found that data measured from these noninvasive sensors can be correlated to etch results. In this paper, we discuss the relationship between process parameters and the measurement data from RF sensor and OES such as plasma impedance and optical spectra and using these relationships to analyze and characterize H-ICP source.

• 마이크로전자및패키징학회지
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• 제14권2호
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• pp.59-63
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• 2007

간단한 PCB 공정을 기반으로 하여 저가형의 후막 가스 센서 모듈을 제안하고자 한다. 제안된 센서 모듈은 $NO_2/H_2$ 가스 센서와 습도센서, 그리고 히터를 포함한다. $NO_2/H_2$ 가스와 상대 습도 센서들은 각각 $SnO_2$와 $BaTiO_3$ 나노 입자들을 PCB 기판에서의 IDT(interdigital Transducer)에 프린팅 함으로써 제작되었다. 처음에 1% $H_2$ 가스를 센서 쳄버에 공급하고 4분 후 $H_2$가스 공급을 멈추고 공기를 주입시켰으며, 이러한 동작을 반복적으로 수행하였다. 마찬가지로 $NO_2$로 감지하도록 같은 동작을 실행하였다. $H_2$ 가스에 대한 결과는 도전성의 증가로 인하여 0.8V에서 3.5V로 증가함을 볼 수 있었으며, $H_2$ 가스를 주입한후의 반응 시간은 65초였다. $NO_2$ 가스의 경우는 도전성이 감소함으로써 2.7 V의 전압강하가 일어 났으며, 반응시간은 3초였다.

• 한국가스학회지
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• 제2권3호
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• pp.49-53
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• 1998

온라인 가스 크로마토그래피와 같은 실시간 분석기기는 데이터 채취 및 분석과정의 시간이 오래 걸려 측정 신뢰성이 낮으며 또한 설치 및 보수비용이 많이 들어서, 실제 가스 산업 공정에서는 온도, 압력과 같은 공정의 운전 변수들을 이용하여 간접적으로 가스의 성분 및 양을 감지하는 소프트 센서에 관한 연구가 활발하게 진행 중이다. 본 연구에서는 데이터 기반 소프트 센서의 설계에 있어서 공정 데이터가 갖는 패턴을 잘 반영하여 추정 능력을 높이는 내적 조합모델 PLS를 제안하고, 이를 산업체의 농도 추정 목적으로 적용하였다. 제안된 PLS모델은 기존에 제시된 모델들보다 뛰어난 추정 능력을 보였다.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1051-1060
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• 2003

The heat and mass transfer on two kinds of tube surfaces (bare stainless steel tube and Teflon coated tube) in steam-air mixture flow are experimentally studied to obtain design data for the heat exchanger of the latent heat recovery from flue gas. In the test section, 3-tubes are horizontally installed, and steam-air mixture is vertically flowed from the top to the bottom. The pitch between tubes is 67mm, the out-diameter of tube is 25.4mm, and the thickness is 1.2mm ; blockage factor (cross sectional tube area over the cross sectional area of the test section) is about 0.38. All of sensors and measurement systems (RTD, pressure sensor, flow-meter, relative humidity sensor, etc.) are calibrated with certificated standard sensors and the uncertainty for the heat transfer measurement is surveyed to have the uncertainty within 7%. As experimental results, overall heat transfer coefficient of the Teflon (FEP) coated tube is degraded about 20% compared to bare stainless tube. The degradation of overall heat transfer coefficient of Teflon coated tube comes from the additional heat transfer resistance due to Teflon coating. Its magnitude of heat transfer resistance is comparable to the in-tube heat transfer resistance. Nusselt and Sherwood numbers on Teflon (FEP) coated surface and bare stainless steel surface are discussed in detail with the contact angles of the condensate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.129-130
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• 2008

In this paper, optimal DRIE process conditions for fused quartz are experimentally determined by Taguchi method to develop high-performance inertial sensors based on the fused quartz material, which is known to have high Q-factors. Using Si layer as an etch mask, which was formed by previously developed bonding process of the fused quartz and Si wafer, fused quartz DRIE process was performed. Different 9 flow rate conditions of $C_4F_8$, $O_2$, He gas have been tested and the optimum combination of these factors was estimated. By this work, the ability to fabricate high aspect ratio fused quartz structure was confirmed.

• 센서학회지
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• 제6권3호
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• pp.200-206
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• 1997

열산화시킨 실리콘 웨이퍼 위에 저압화학기상성장법으로 $SiCl_{2}H_{2}$, $NH_{3}$ 및 $N_{2}O$ 기체를 사용하여 실리콘 옥시나이트라이드($Si_{x}O_{y}N_{z}$) 층을 제작하였다. 세 가지의 다른 조성이 기체 유속비($NH_{3}/N_{2}O$)를 각기 0.2, 0.5 및 2로 변화시키고 $SiCl_{2}H_{2}$의 기체 유속은 고정시킴으로써 얻어졌다. 엘립소메트리와 HFCV(High Frequency Capacitance-Voltage) 측정법을 채택하여 굴절율, 유전율 및 조성의 차이를 각각 조사했다. 실리콘 옥시나이트라이드는 내부에 포함된 실리콘 나이트라이드 성분량에 관계없이 용액 중에서 순수한 실리콘 나이트라이드와 유사한 안정성을 보유했다. 실리콘 옥시나이트라이드 층 알칼리이온 감지성의 크기 순서는 실리콘 나이트라이드 성분량에 영향을 받았다. 보다 나은 알칼리이온 감지성이 실리콘 옥시나이트라이드의 벌크 내에 있는 실리콘 디옥시드의 성분량을 증가시킴으로써 얻어졌다.