• 한국재료학회지
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• 제31권12호
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• pp.697-703
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• 2021

Aluminum nitride having a dense hexagonal structure is used as a high-temperature material because of its excellent heat resistance and high mechanical strength; its excellent piezoelectric properties are also attracting attention. The structure and residual stress of AlN thin films formed on glass substrate using TFT sputtering system are examined by XRD. The deposition conditions are nitrogen gas pressures of 1 × 10^-2, 6 × 10^-3, and 3 × 10^-3, substrate temperature of 523 K, and sputtering time of 120 min. The structure of the AlN thin film is columnar, having a c-axis, i.e., a <00·1> orientation, which is the normal direction of the glass substrate. An X-ray stress measurement method for crystalline thin films with orientation properties such as columnar structure is proposed and applied to the residual stress measurement of AlN thin films with orientation <00·1>. Strength of diffraction lines other than 00·2 diffraction is very weak. As a result of stress measurement using AlN powder sample as a comparative standard sample, tensile residual stress is obtained when the nitrogen gas pressure is low, but the gas pressure increases as the residual stress is shifts toward compression. At low gas pressure, the unit cell expands due to the incorporation of excess nitrogen atoms.

• 한국막학회:학술대회논문집
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• 한국막학회 1991년도 추계 총회 및 학술발표회
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• pp.4-8
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• 1991

The characterization of pore properties (mean pore size and pore size distribution) of the active layer in a UF membrane is important not only in order to obtain information about the factors affecting pore formation during membrane manufacturing but also to understand deeply the mechanism of solute and solvent transport through pores. Many methods of characterizing quantitatively the pore properties of UF membranes have been suggested in the literature: solvent and gas flow measurement, bubble point determination, electron microscopy, gas adsorption/desorption measurement, rejection measurement etc. But most of these methods involve time-consuming procedures and involve some wellknown problems and uncertainties.

• 조명전기설비학회논문지
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• 제20권10호
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• pp.114-119
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• 2006

본 논문에서는 세 가지 종류의 가스센서를 사용하여 수소가스에 대한 정량화 및 선택도를 향상시키기 위한 연구를 수행하였다. 여러 가지 수소가스 농도에 대한 각 가스센서들의 출력을 측정하였고 높은 출력과 분해능특성을 보이는 농도범위를 분석한 결과 세 가지 종류의 센서의 사용은 10,000[ppm]까지의 광대역의 수소가스농도를 신뢰성 있게 측정할 수 있는 가능성을 보여주었다. 또한 어떠한 농도의 메탄($CH_4$) 및 일산화탄소에 대한 출력과 수소에 대한 출력을 비교한 결과 세 가지 센서의 출력을 조합하면 수소가스의 선택성을 향상시킬 수 있는 것으로 나타났다.

• 한국입자에어로졸학회지
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• 제12권1호
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• pp.21-26
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• 2016

In order to realize In-line and convenient measurement for solid-gas two phase flows, Light Transmission Fluctuation (LTF) based on the random variation of transmitted light intensity, light scattering theory and cross-correlation method was presented for online measurement of particle size, concentration and velocity. The statistical relationship among transmitted light intensity, particle size and particle number in measurement zone was described by Beer-Lambert Law. Accordingly, the particle size and concentration were determined from the fluctuation signal of transmitted light intensity. Simultaneously, the particle velocity was calculated by cross-correlation analysis of two neighboring light beams. By considering the influence of concentration variation in industrial applications, the improved algorithm based on spectral analysis of transmitted light intensity was proposed to improve measurement accuracy and stability. Therefore, the online measurement system based on LTF was developed and applied to measure pulverized coal in power station and raw material in cement plant. The particle size, concentration and velocity of powder were monitored in real-time. It can provide important references for optimal control, energy saving and emission reduction of energy-intensive industries.

• 한국진공학회지
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• 제22권5호
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• pp.231-237
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• 2013

본 연구에서는 분동식 기준압력계의 기준분동(reference weight)의 부피를 측정하는 새로운 측정방법인 기체용적계(gas pycnometer) 측정방법을 제안하였다. 제안된 측정방법에 의한 측정결과로서 기준분동 1 kg, 2 kg, 5 kg에 대한 부피 측정불확도는 신뢰수준 95%에서 0.2%를 나타내었다. 기체용적계의 주요 장치는 샘플용기와 팽창용기, 정밀압력계, 정밀온도계, 진공펌프로 구성되며, 측정 원리는 일정한 용기 내에 들어 있는 일정한 양의 기체의 압력과 부피는 서로 반비례한다는 보일(boyle's law)의 법칙을 용용하였다. 본 결과는 현재까지 문헌이나 제조사로부터 기준분동 재질에 대한 밀도값을 적용하여 오던 것을 기준분동의 부피를 직접 측정하여 밀도값을 적용함으로서 압력기준기의 압력 기준값에 대한 국가측정표준의 신뢰도 향상에 기여될 것이다.

• Journal of Korean Society for Atmospheric Environment
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• 제23권E2호
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• pp.66-73
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• 2007

The introduction of tracer gas techniques to ventilation studies in indoor environments provides valuable information that used to be unattainable from conventional testing environments. Data acquisition systems (DASs) containing analogue-to-digital (A/D) converters are usually used to function the key role that records signals to storage in digital format. In the testing process, there exist a number of components in the measuring equipment which may produce system-based inference to the monitored results. These unwanted fluctuations may cause significant error in data analysis, especially when non-linear algorithms are involved. In this study, a pre-processor is developed and applied to separate the unwanted fluctuations (noise or interference) in raw measurements and to reduce the uncertainty in the measurement. Moving average, notch filter, FIR (Finite Impulse Response) filters, and IIR (Infinite Impulse Response) filters are designed and applied to collect the desired information from the raw measurements. Tracer gas concentrations are monitored during leakage and ventilation tests in the model test room. The signal analysis functions are introduced to carry out the digital signal processing (DSP) work. Overall the FIR filters process the $CO_2$ measurement properly for ventilation rate and mean age of air calculations. It is found that, the Kaiser filter was the most applicable digital filter for pre-processing the tracer gas measurements. Although the IIR filters help to reduce the random noise in the data, they cause considerable changes to the filtered data, which is not desirable.

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.629-636
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• 2003

This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.27-28
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• 2012

Tunable diode laser absorption spectroscopy(TDLAS) measurement techniques for several gases densities and temperatures have been applied in industrial combustion systems. Accurate measurement of temperature profile is very important, especially in power plants and heating furnaces. So profile fitting and temperature binning methods are new issue for accurate measurement of temperature in laser gas sensing. Temperature binning method is applied in this study for the measurement of temperature profile using tube furnace with three temperature zones. In this study the temperature profiles of tube furnace is accurately measured within 5% error, and this technique is proved to be very promising in the field of temperature profile measurement.

• Journal of Mechanical Science and Technology
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• 제20권12호
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• pp.2284-2291
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• 2006

The present study investigates gas residence time and mixing characteristics for various swirl numbers generated by injection of secondary air into a lab-scale cylindrical combustor. Fine dust particles and butane gas were injected into the test chamber to study the gas residence time and mixing characteristics, respectively. The mixing characteristics were evaluated by standard deviation value of trace gas concentration at different measurement points. The measurement points were located 25 mm above the secondary air injection position. The trace gas concentration was detected by a gas analyzer. The gas residence time was estimated by measuring the temporal pressure difference across a filter media where the particles were captured. The swirl number of 20 for secondary air injection angle of 5$^{\circ}$ gave the best condition: long gas residence time and good mixing performance. Numerical calculations were also carried out to study the physical meanings of the experimental results, which showed good agreement with numerical results.

• 신재생에너지
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• 제2권2호
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• pp.102-107
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• 2006

In Japan, research and development were undertaken on gas hydrate-side industrial processes associated with power generation system connections that may particularly be necessary to develop gas hydrated technology-based industrial systems. In so doing, data and engineering technologies useful n formulating guidelines on design of practical process were accumulated. In addition, basic research into theoretical evidence were carried out to promote and support the development of technological elements for those processes. In basic research designed to promote and support the research and development of elemental technologies, microanalyses were conducted to understand the decomposition mechanism of mixed gas hydrate. Moreover, measurement technologies that can be applied in industrial processes, such as numerical analyses and concentration measurement, were examined. Japan has developed a highly efficient gas hydrate formation process using micro-bubbles with a tubular reactor. Higher formation rate over conventional systems has been obtained by the process. As mentioned above, the technical problems were clarified and the economics were studied from a view point of the NGH technology in this study. The results can be applied for utilization and must contribute to popularization of gas hydrate production.