• Title/Summary/Keyword: chamber method

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A Modified Simple Acoustic Analysis of Rectangular Simple Expansion Chamber with Consideration of Higher Order Modes (고차모드를 고려한 사각형 단순 확장관의 간편음향해석법의 개선)

  • 김봉준;정의봉;황상문
    • Journal of KSNVE
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    • v.9 no.2
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    • pp.340-347
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    • 1999
  • The acoustic performance of reactive type single expansion chamber can be calculated theoretically by plane wave theory. But higher order model should be considered to widen the frequency range. Mode matching method has been developed to consider higher order modes, but very complicated algebra should be used. Munjal suggested a numerical collocation method, which can overcome the shortcomings of mode matching method, using the compatibility conditions for acoustic pressure and particle velocity at the junctions of area discontinuities. But the restriction of Munjal's method is that the ratio between the area of inlet(or outlet) pipe and that of chamber must be natural number. In this paper, the new method was suggested to overcome the shortcomings of Munjal's method. The predictions by this method was also compared with those by the finite element method and Munjal's method in order to demonstrate the accuracy of the modified method presented here.

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A Simplified Closed Static Chamber Method for Measuring Methane Flux in Paddy Soils (논토양(土壤)의 메탄 배출(排出) 측정(測定)을 위한 간역폐쇄정태(簡易閉鎖靜態) Chamber법(法))

  • Shin, Yong-Kwang;Lee, Yang-Soo;Yun, Seong-Ho;Park, Moo-Eon
    • Korean Journal of Soil Science and Fertilizer
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    • v.28 no.2
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    • pp.183-190
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    • 1995
  • Various factors such as sampling height in the chamber, sampling interval, sampling time at daytime and the effects of pedoturbation on methane emission during chamber installation were evaluated using a simplified closed static chamber method to measure methane flux in paddy soils. Sampling height of the chamber for representative samples was 65cm. An additional DC fan was required to attain an even methane gradient in the chamber. Considering the change of methane concentration and air temperature in the chamber, sampling is recommended to finish within 30 minutes after starting sampling. The aim of setting DC fan in the chamber was to get the thermal equilibrium in the chamber as well as the representative samples. Suitable time to collect the gas samples representing the day's methane flux was 0900~1200 hours. Gas sampling was possible even after installation of small chambers if the elapsed time was more than 6 hours and supporting stand would be to be added to minimize pedoturbation.

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Experimental Measurement and Monte Carlo Simulation the Correction Factor for the Medium-Energy X-ray Free-air Ionization Chamber

  • Yu, Jili;Wu, Jinjie;Liao, Zhenyu;Zhou, Zhenjie
    • Journal of the Korean Physical Society
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    • v.73 no.10
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    • pp.1466-1472
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    • 2018
  • A key comparison has been made between the air-kerma standards of the National Institute of Metrology (NIM), China, and other Asia Pacific Metrology Programme (APMP) members in the medium-energy X-ray. This paper reviews the primary standard Free-air ionization chamber correction factor experimental method and Monte Carlo simulation method in the NIM. The experimental method and the Monte Carlo simulation method are adopted to obtain the correction factor for the medium-energy X-ray primary standard free-air ionization chamber at 100 kV, 135 kV, 180 kV, 250 kV four CCRI reference qualities. The correction factor has already been submitted to the APMP as key comparison data and the results are in good agreement with those obtained in previous studies. This study shows that the experimental method and the EGSnrc simulation method are usually used in the measurement of the correction factor. In particular, the application of the simulation methods is more common.

Validating of small chamber method by CFD simulation and VOCs emission rate of construction materials. (소형 챔버법에 의한 건축자재의 휘발성유기화합물 방출량 측정 및 CFD해석)

  • Kim, Yun-Deok
    • Journal of the Korean Solar Energy Society
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    • v.26 no.3
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    • pp.99-110
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    • 2006
  • This study focused on the emission rate of the construction materials. The method of study is as follows. First, validation of small chamber method to determine emission rate of construction material was performed by CFD simulation. For the result of this study, uniform air velocity in small chamber was founded, and small chamber as a test material for emission rate was validated. Second, the construction materials were categorized by their feature and the emission rate of volatile organic compound was determined. Totally, VOCs emission rate of 49 materials were determined.

Optimization of the Material and Structure of Component Parts for Reducing the Number of Impurity Particles in CVD Process

  • Kim, Won Kyung;Woo, Ram;Roh, Jong Wook
    • Journal of the Korean Ceramic Society
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    • v.56 no.3
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    • pp.277-283
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    • 2019
  • We have examined minimization of the number of impurity particles by replacing the load-lock chamber materials of the chemical vapor deposition equipment through optimization of the pumping method in the deposition chamber. In order to reduce the number of impurity particles in the chamber, the load-lock spacer material was changed from monomer casting nylon to Torlon. Furthermore, we controlled the pumping speed and number of pumping ports, which resulted in a reduction in the impurity particle generation from 2.67% to 0.52%. This study revealed that the selection of the material for the parts of a chemical vapor deposition chamber can minimize particle generation, thereby presenting a method of optimization method of the chemical vapor deposition chamber.

Comparison of CH4 Emission between Auto Chamber and Manual Chamber in the Rice Paddy (벼논에서 자동 챔버와 수동 챔버를 이용한 CH4 배출량 비교)

  • Jeong, Hyun Cheol;Choi, Eun Jung;Lee, Jong Sik;Kim, Gun Yeob;Lee, Sun Il
    • Journal of Climate Change Research
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    • v.9 no.4
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    • pp.377-384
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    • 2018
  • The chamber method is widely used for measuring methane emission from paddy rice fields. The closed static chamber has advantages of easy installation and removal in the field and low manufacturing cost. However, the manual chamber method requires a lot of labor and has a limited sampling time and frequency. To overcome the disadvantages of the manual chamber, the auto-chamber system is used for measuring methane emission. We compared the differences in methane flux between the auto-chamber and manual chamber. To investigate methane emissions by the two methods, a chamber was installed for each of the following treatments : control without rice straw (NA), spring plowing after autumn rice straw application (SPRA) and autumn plowing after autumn rice straw application (APRA). The total methane emission was lowest in the control and highest in APRA with both methods. There was no significant difference in total methane emission between the methods, but dynamic fluctuation in methane with temperature change was accurately measured in the auto-chamber. Measuring methane emission with an auto-chamber system is expected to reduce uncertainty and increase accuracy, accompanied by labor reduction.

On the Method for Hot-Fire Modeling of High-Frequency Combustion Instability in Liquid Rocket Engines

  • Sohn, Chae-Hoon;Seol, Woo-Seok;Valery P. Pikalov
    • Journal of Mechanical Science and Technology
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    • v.18 no.6
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    • pp.1010-1018
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    • 2004
  • This study presents the methodological aspects of combustion instability modeling and provides the numerical results of the model (sub-scale) combustion chamber, regarding geometrical dimensions and operating conditions, which are for determining the combustion stability boundaries using the model chamber. An approach to determine the stability limits and acoustic characteristics of injectors is described intensively. Procedures for extrapolation of the model operating parameters to the actual conditions are presented, which allow the hot-fire test data to be presented by parameters of the combustion chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for designers. Tests with the model chamber, based on the suggested scaling method, are far more cost-effective than with the actual (full-scale) chamber and useful for injector screening at the initial stage of the combustor development in a viewpoint of combustion instabilities.

Measurement of Semi-Volatile Organic Compounds from Flooring Material and Evaluation on Airflow Characteristics in a Test Chamber (바닥재에서 발생하는 준휘발성유기화합물 측정 및 챔버 내 기류 특성 평가)

  • Seo, Jang-Hoo;Kato, Shinsuke;Lim, Mann-Taek
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.762-767
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    • 2009
  • Some types of semi-Volatile organic compounds (SVOC) that are emitted from plastics used in building materials and household appliances have associated health risks, even at low concentrations. In this study, micro chamber method for measuring SVOC is introduced and SVOC such as di (2-ethylhexyl) phthalate and butylated hydroxyltoluene emitted a flooring material were measured using a micro chamber method. Airflow characteristics in a micro test chamber deeply depended on air exchange rate. From the evaluation using an index of air change efficiency, such as the air age and the coefficient of air change performance, a fixed air exchange rate of $1.5\;h^{-1}$ in the micro chamber is desirable.

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Consideration of Measurement Method for SVOCs Emission Rates (실내 준휘발성유기화합물 방출량 측정법에 대한 고찰)

  • Seo, Jang-Hoo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.5
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    • pp.375-382
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    • 2011
  • Semi volatile organic compounds (SVOCs) are used as plasticizers in building materials, interior materials, furniture, consumer electronics. etc. In the home, these SVOCs mix together with house dust. There is thus concern over the health effects of SVOCS in the home, there is a risk that they ini1uence childhood asthma and allergies. It is difficult to measure SVOCs emission rates from building materials or household appliances utilizing the usual test chamber methods, because the boiling points of SVOCs are higher and they are apt to adhere to the surface of the test chamber used. In this study, we introduce FLEC chamber method, passive sampler method and micro chamber method, which are used in Germany and Japan in order to measure SVOCs emission rates. Characteristic, merits and demerits of test methods are also considered.

STUDY ON PRE-MIXTURE COMBUSTION IN A SUB-CHAMBER TYPE CVC WITH MULTIPLE PASSAGE HOLES

  • PARK J. S.;YEOM J. K.;LEE T. W.;HN J. Y.;CHUNG S. S.
    • International Journal of Automotive Technology
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    • v.7 no.1
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    • pp.17-23
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    • 2006
  • An experimental study was carried out to obtain the fundamental data about the effect of sub-chamber on pre-mixture combustion. A eve (constant volume combustor) divided into a sub-chamber and a main chamber was used in this experiment. The volume of the sub-chamber was varid trom $0.45\%$ to $1.4\%$ about the whole combustion chamber. The sub-chamber has twelve narrow radial passage holes and a spark plug to ignite the pre-mixture. As the ignition occurs in the sub-chamber by a spark discharge, burned and unburned gas including a great number of radicals is injected into the main chamber, then the multi-point ignition occurs in the main chamber. The combustion pressure is measured to calculate the burning velocity mainly as a function of the sub-chamber volume, the diameter of the passage holes, and the equivalence ratio. In the case of RI (radical ignition) methods, the overall burning time became very short and the maximum burning pressure was slightly increased as compared with that of SI (spark ignition) method. The optimum design value of the sub-chamber is near 0.11 $cm^{-l}$ in the ratio of total area of holes to the sub-chamber volume.