• 한국음향학회지
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• 제31권4호
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• pp.225-234
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• 2012

The anechoic chamber is essential tool to measure the various acoustic parameters with high precision. The chamber provides the climate controlled indoor environments but requires the dedicated room at a great cost in order to isolate and absorb sound field. Provided the purpose of the chamber is specific to the experiments of sound localization, the performance requirements excluding free field can be alleviated for cost effective solution. This paper designs low cost and profile anechoic chamber based on acoustic pyramids and evaluates the performance specified by the Annex of ISO 3745. Data analysis is employed to measure the free and hemi-free field performance over five straight paths for working areas and four paths for non-working areas. The identical two measurement campaigns were conducted for free and hemi-free field chamber which is easily interchangeable by simple labor in this chamber design. In the working area with conventional speaker, the results of these analyses demonstrate that lab-designed anechoic chamber is in conformance with ISO 3745 for 250 Hz - 16 kHz one-third octave band at free field chamber and for 1 kHz - 16 kHz one-third octave band at hemi-free field chamber.

• Journal of Korean Society for Atmospheric Environment
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• 제17권E2호
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• pp.61-70
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• 2001

In recent years there have been growing interests in the potential environmental effects of global climate change. Of specific interests is the role that climate change may play in altering natural volatile organic compound.(NVOC) emissions from trees and the subsequent impact of this perturbation on air quality and ozone formation. A novel vegetation enclosure chamber method was designed and constructed of Tedlar in order to estimate more accurate and precise NVOC emission rates of either small whole plants or the branches of large trees. The enclosure chamber was initially tested in the laboratory and also successfully evaluated in the field. Overall precision for this enclosure was estimated as RSD<10%(n=9). The overall errors associated with the enclosure method in a laboratory system might be relatively small (say<$\pm$15%); however, they might be rather large(say$\pm$40%) in a field-based system. Two consecutive samples were collected on each sampling day from the two pine species during the test period. Slash pine studies showed that the absolute percentage difference between the first and second samples varied from 0.33 to 29%. The percent differences between consecutive emission for loblolly pines varied from 0.74 to 24.2%.

• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2014년도 추계 학술발표논문집
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• pp.146-150
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• 2014

• 한국환경농학회지
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• 제29권4호
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• pp.374-380
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• 2010

본 연구에서는 농촌진흥청에서 개발한 LED Chamber System을 이용하여 명기시간 동안 광질과 광조사 방법 제어가 단절단엽의 국화 배양소식물체(Dendranthema grandiflorum L., cv. 'Cheonsu')의 생장에 미치는 영향을 검토하였다. 실험은 청색, 적색 및 녹색의 단일광질 또는 청색+적색, 청색+녹색 및 적색+녹색의 혼합광질 조건하에서 이들 광질을 명기 16시간 동안 연속적으로 또는 초당 50회 간격과 분당 20초간격으로 간헐적으로 제어하면서 42일간 수행하였다. 총 일장을 4시간 단축한 분당 20초 간격의 간헐조사는 관행의 형광등 연속조사에 비해 국화의 절간길이 신장에 의한 신초신장을 촉진하였으나, 배양소식물체의 양적생장은 연속광 처리에 의해 유의하게 증가하였다. 한편, 명기동안 녹색광을 초당 50회 간격으로 간헐제어한 경우 연속조사에 비해 건물중이나 엽면적 증대와 같은 양적생장은 억제되었으나 형태적인 면에서의 절간신장은 촉진되었다. 따라서, LED Chamber System을 이용한 광질이나 광조사 방법의 제어는 관행의 형광등 이용 연속조사에 비해 명기시간 단축에 의한 전력소모량 감소 및 기내 배양소식물체의 생장이나 형태제어에 효과적인 배양기술로 이용 가능할 것으로 판단된다.

• 대한설비공학회지:설비저널
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• 제23권2호
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• pp.97-108
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• 1994

• 한국초지조사료학회지
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• 제41권3호
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• pp.183-188
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• 2021

The increase in temperature due to climate warming is predicted to affect crop yields in the future. Until now, various types of OTC (open top chamber) that simulate the future climate condition have been developed and used to study the effect of temperature increase due to global warming on maize growth. However, in most OTCs, high equipment and maintenance costs were required to artificially increase the temperature. This study was carried to develop a cost-effective and simple OTC suitable for climate warming experiments for forage maize. Three octagonal OTCs with a height of 3.5 m × a diameter of 4.08 m and a partially covered top were constructed. The lower part of OTC covered film was opened at a height of 26 cm (OTC-26), 12 cm (OTC-12) from the ground surface, or not opened (0 cm, OTC-0). Mean air temperatures during the daytime on a sunny day in OTC-0, OTC-12 and OTC-26 increased to 3.23℃, 1.33℃, and 0.89℃, respectively, compared to the ambient control plot. For a pilot test, forage maize, 'Gwangpyeongok' was grown at OTCs and ambient control plots. As a result, in the late maize vegetative growth phase (July 30), the plant height was increased more than 45% higher than the ambient control plot in all OTC plots, and the stem diameter also increased in all OTC plots. These results indicate that it is possible to set the temperature inside the OTC by adjusting the opening height of the lower end of the OTC, and it can be applied to study the response of forage maize to elevated temperature. An OTC, with its advantages of energy free, low maintenance cost, and simple temperature setting, will be helpful in studying maize growth responsiveness to climate warming in the future.

• 한국환경과학회지
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• 제32권2호
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• pp.131-137
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• 2023

Filter and microbalance sensitivity in measuring fine particulate matter mass is greatly influenced by particulate properties and environmental factors. Temperature and humidity control inside a measuring chamber with a microbalance, and neutralization of static charges on filters are essential for consistent filter weighing. Commercial weighing chambers are expensive with a unit price of tens of millions won. This study developed an inexpensive weighing chamber for weighing fine particulate matter and evaluatedits weighing performance. A microbalance with 1 ㎍ precision was used to measure the weight of a filter. The microbalance was set in a transparent acrylic enclosure (100 × 60 × 65 cm³) equipped with temperature and humidity control equipments. Weighing performance of the chamber was examined using Teflon filters with or without different particulate sample types. Temperature and humidity were maintained at approximately 23.2±1.2 ℃ and 36.2±1.8℃ for 8 days, respectively.

• 한국농림기상학회지
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• 제22권2호
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• pp.79-91
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• 2020

온실가스 배출량의 정확한 평가는 모든 기후변화 대응 연구의 초석이며, 신뢰성이 높은 온실가스 배출량의 평가는 모든 기후변화 예측 및 모델링 연구의 실질적인 기초자료로서 활용된다. 온실가스 배출량 산정 기반 기술로서 온실가스 배출량 현장 모니터링 기술, 배출계수의 불확도 평가 기술, 온실가스 배출량 및 저감량 검증 기술 등이 필수적이다. 이런 기반 기술의 핵심에는 토양-식생-대기 간에 교환되는 온실가스 플럭스 산정을 위해 가장 보편적으로 많이 사용되는 폐쇄형 정적 챔버법의 모니터링 기술이 자리 잡고 있다. 본 연구에서는 농업분야 온실가스 단일 배출원으로 가장 큰 부분을 차지하는 벼논에서 발생하는 CH₄ 플럭스 측정용 폐쇄형 챔버법의 기술적 근간과, 수동형 챔버법에서 전 과정의 자동화 시스템으로 발전을 거듭하고 있는 자동화 챔버 모니터링 기술개발에 대한 국내·외 동향을 소개하였다. 이를 바탕으로 보편적으로 사용하고 있는 챔버법의 표준화된 방법의 고찰과 정확한 현장 자료를 얻기 위한 품질관리 방안이 마련될 수 있을 것이다. 또한 CH₄ 플럭스 측정방법의 신뢰성 높은 기술 발전 방향에 대해 조망하여 벼논 CH₄ 배출량 산정 결과들의 신뢰성 향상에 기여하게 될 것으로 전망한다.

• 대기
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• 제27권4호
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• pp.499-509
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• 2017

Possible links among cosmic ray, cloud, and climate have scientific uncertainties. The reputed topics have been highly controversial during several decades. A link between the atmospheric ionization by galactic cosmic rays (GCR), which is modulated by solar activities, and global cloud cover was firstly proposed in 1997. Some researchers suggested that the GCR can stimulate the formation of cloud condensation nuclei (CCN) in the atmosphere, and then the higher CCN concentrations may lead to an increase of cloud cover, resulting in a cooling of the Earth's climate, and vise versa. The CLOUD (Cosmic leaving outdoor droplets) experiment was designed to study the effect of GCR on the formation of atmospheric aerosols and clouds under precisely controlled laboratory conditions. A state-of-the-art chamber experiment has greatly advanced our scientific understanding of the aerosol formation in early stage and its nucleation processes if the GCR effect is considered or not. Many studies on the climate-GCR (or space weather) connection including the CLOUD experiment have been carried out during the several decades. Although it may not be easy to clarify the physical connection, the recent scientific approaches such as the laboratory experiments or modeling studies give some implications that the research definitively contributed to reduce the scientific uncertainties of natural and anthropogenic aerosol radiative forcing as well as to better understand the formation processes of fine particulate matters as an important parameter of air quality forecast.

• 한국의류산업학회지
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• 제11권6호
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• pp.947-952
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• 2009

The purpose of this study is to analyze skin wettedness($w$) used as the rate index of thermal comfort, and to evaluate the wear comfort of outdoorwear. Skin wettedness is widely used to express the degree of thermal comfort. If skin wettedness exceeds a certain threshold, the body feels damp and discomfort. An experiment which consisted of rest(30 min), exercise(30 min) and recovery(20 min) periods was administered in a climate chamber with 10 healthy male participants. Two kinds of outdoorwears made of 100% cotton fabrics (Control) and specially engineered fabrics having feature of quick sweat absorbency and high speed drying fabric (Functional) were evaluated in the experiment. The condition of climate chamber was controlled according to the thermal insulation of 4 kinds of experimental ensembles(E1~E4). Total sweat loss, sweat loss absorbed into clothing and skin temperature were measured. Skin wettedness was calculated from the ratio of evaporative rate to the maximal evaporative capacity. Skin wettedness of 'Functional' was lower than 'Control' in the 3 kinds of ensembles(E1, E2, E4) because the materials of 'Functional' were composed of quick sweat absorbency and high speed drying fabrics, water vapour permeability and waterproof fabrics.