• 한국항행학회논문지
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• 제22권1호
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• pp.13-19
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• 2018

본 논문에서는 저고도 무인기 교통관리 체계에서 운용될 무인기의 사용 용도별로 비행패턴을 분석하였고, 시뮬레이션 모형을 개발하였다. 무인기 비행패턴은 감시형, 선회형, 배송형 패턴으로 분류하였으며, 무인기 사용 용도별로는 농업, 시설 점검, 공공안전 및 보안, 물품 배송으로 총 네 가지 경우를 고려하였다. 또한 저고도 무인기 교통관리 체계에 적용할 공역 운용방식을 검증하기 위한 도구로써 시뮬레이션 모형을 개발하였다. 개발된 시뮬레이션 모형을 감시형 비행패턴에 적용해 보았으며, 그 결과 정해진 입력을 받아 주어진 비행패턴을 그리며 비행하는 것을 확인 및 검증하였다. 본 시뮬레이션 모형은 향후 무인기가 다양한 비행패턴을 그리며 해당 용도에 맞게 안전하고 효율적으로 운항할 수 있는지 검증하는데 사용될 예정이다.

• 대한기계학회논문집A
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• 제35권7호
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• pp.759-766
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• 2011

최근 가정용 에어컨은 냉방효율뿐 아니라 소음에 대한 중요성이 지속적으로 높아지고 있다. 로터리 압축기는 에어컨의 소음 중 매우 높은 영향도를 가지고 있으며, 압축기의 소음을 줄이기 위해 머플러 및 공명기에 관한 많은 연구들이 진행되어 왔다. 압축기의 부품 중 어큐뮬레이터는 큰 용적으로 인해 공명에 의한 추가 소음을 에어컨에 전달하는 소음 전달경로가 되며, 어큐뮬레이터의 내부구조는 소음저감을 위해 중요한 설계요소가 되나 지금까지는 연구결과가 미비한 수준이었다. 본 논문에서는 어큐뮬레이터의 소음 저감을 위해 목표주파수 대역에서의 투과손실이 최대가 되는 설계최적화를 수행하였다. 높은 비선형성을 가진 문제의 최적화를 위해 실험계획법과 반경기저신경망기법을 이용한 근사 모델을 사용하였으며, 유전알고리즘을 사용한 최적화를 수행하였다.

• 한국소음진동공학회논문집
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• 제17권8호
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• pp.683-692
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• 2007

Recently, plastic products in air-intake parts of automotive engines have become very popular due to advantages that include reduced weight, constricted cost, and lower intake air temperature. However, flow-induced noise in air-intake parts becomes a more serious problem for plastic intake-manifolds than for conventional aluminum-made manifolds. This is due to the fact that plastic manifolds transmit more noise owing to their lower material density. Internal aerodynamic noise from an idle speed control actuator(ISA) is qualitatively analyzed by using a scaling law, which is expressed with some flow parameters such as pressure drop, maximum flow velocity, and turbulence kinetic energy. First, basic flow characteristics through ISA passage are identified with the flow predictions obtained by applying computational fluid dynamics techniques. Then, the effects on ISA passage noise of each design factors including the duct turning shape and vane geometries are assessed. Based on these results, the preliminary low noise design for the ISA passage are proposed. The current method for the prediction of internal aerodynamic noise consists of the steady CFD and the scaling laws for the noise prediction. This combination is most cost-effective, compared with other methods, and therefore is believed to be suited for the preliminary design tool in the industrial field.

• Journal of Microbiology and Biotechnology
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• 제30권11호
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• pp.1785-1791
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• 2020

In a previous study, the sequential optimization and regulation of environmental parameters using the PhotoBiobox were demonstrated with high-throughput screening tests. In this study, we estimated changes in the biovolume-based composition of a polyculture built in vitro and composed of three algal strains: Chlorella sp., Scenedesmus sp., and Parachlorella sp. We performed this work using the PhotoBiobox under different temperatures (10-36℃) and light intensities (50-700 μmol m^-2 s^-1) in air and in 5% CO₂. In 5% CO₂, Chlorella sp. exhibited better adaptation to high temperatures than in air conditions. Pearson's correlation analysis showed that the composition of Parachlorella sp. was highly related to temperature whereas Chlorella sp. and Scenedesmus sp. showed negative correlations in both air and 5% CO₂. Furthermore, light intensity slightly affected the composition of Scenedesmus sp., whereas no significant effect was observed in other species. Based on these results, it is speculated that temperature is an important factor in influencing changes in algal polyculture community structure (PCS). These results further confirm that the PhotoBiobox is a convenient and available tool for performance of lab-scale experiments on PCS changes. The application of the PhotoBiobox in PCS studies will provide new insight into polyculture-based ecology.

• 한국지리정보학회지
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• 제14권2호
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• pp.109-127
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• 2011

대기 에어러솔은 대기중에 존재하는 미세입자로 인체 유해성을 지니고 있으며 기후변화에 있어서도 중요한 역할을 하는 변수로 알려져 있다. 게다가 대기 에어러솔의 주요 성분에 대한 정확한 평가는 환경에 미치는 영향에 있어서도 매우 중요하다. 이 때문에 지구관측 위성자료는 대기질 감시측면에서도 효과적인 수단으로 이용되고 있다. 따라서 본 연구에서는 인공위성 관측 자료를 이용하여 전구적인 규모의 대기 에어러솔의 주요 성분별 분포변화를 알아보고자 MODIS 에어러솔 광학두께(AOT; Aerosol Optical Thickness)와 미세입자분율(FMF; Fine Mode Fraction), 그리고 TOMS 자외선 흡수성 에어러솔 지수(AAI; UV Absorbing Aerosol Index)를 이용하여 네 가지의 주요 에어러솔의 성분(먼지, 탄소성, 황산화물, 해염)을 구분할 수 있는 방법을 제시하였다. 여기서 얻어진 결과물을 검증하기 위하여 에어러솔 예측 모델자료와 각 격자별 자료로 선형회귀분석을 수행한 결과, 본 연구에서 산출된 결과물이 에어러솔의 성분별 전반적인 패턴을 잘 표현하는 것을 확인 할 수 있었다. 이렇게 주요 에어러솔 타입으로 구분된 위성자료의 사용은 대기질 감시뿐만 아니라 기후변화연구에 있어서도 도움을 줄 것으로 사료된다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.259-264
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• 2009

Most of the fossil power plants firing lower grade coals are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. The poor combustion conditions are directly related to the gas flow deviation in upper furnace and convection tube-bank but a less reported issue related to in large-scale oppose wall fired boilers. In order to develop a on-line combustion monitoring system and suggest an alternative heat flux estimation method at tube bank, which is very useful information for boiler design tool and blower optimizing system, field test was conducted at operating power boiler. During the field test the exhaust gases' temperature and tube metal temperature were monitored by using a spatially distributed sensors grid which located in the boiler's high temperature vestibule region. At these locations. the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. Test results showed that the flue gas monitoring method is more proper than metal temperature distribution monitoring for real time combustion monitoring because tube metal temp. distribution monitoring method is related to so many variables such as flue gas, internal flow unbalance, spray etc., Heat flux estimation at the tube bank with flue gas temp. and metal temp. data can be alternative method when tube drilling type sensor can't able to use.

• 대한방사선기술학회지:방사선기술과학
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• 제42권4호
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• pp.291-299
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• 2019

The International Electrotechnical Commission (IEC) has regulated the definition and requirements of the exposure index (EI). In this study, we calculated the EI of several image receptors in digital radiography system of two different manufacturers according to the method as per IEC, and evaluated the relationship with incident air kerma. To calculate the EI, w e obtained the characteristics curve of each image receptor by increasing the incident air kerma at RQA 3, 5, 7 and 9, respectively. As a result, there was no significant difference in the EI values between different image receptors of the same manufacturer, but EI values of different manufacturer was different despite the same air kerma was incident. Therefore, understanding the characteristics of the digital radiography systems is important in order to use EI as a tool for measuring and managing the radiation dose.

• 대기
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• 제31권5호
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• pp.473-488
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• 2021

A new physical/statistical diagnostic downscale model has been developed for use to improve near-surface air temperature forecasts. The model includes a series of physical and statistical correction methods that account for un-resolved topographic and land-use effects as well as statistical bias errors in a low-resolution atmospheric model. Operational temperature forecasts of the Local Data Assimilation and Prediction System (LDAPS) were downscaled at 100 m resolution for three months, which were used to validate the model's physical and statistical correction methods and to compare its performance with the forecasts of the Korea Meteorological Administration Post-processing (KMAP) system. The validation results showed positive impacts of the un-resolved topographic and urban effects (topographic height correction, valley cold air pool effect, mountain internal boundary layer formation effect, urban land-use effect) in complex terrain areas. In addition, the statistical bias correction of the LDAPS model were efficient in reducing forecast errors of the near-surface temperatures. The new high-resolution downscale model showed better agreement against Korean 584 meteorological monitoring stations than the KMAP, supporting the importance of the new physical and statistical correction methods. The new physical/statistical diagnostic downscale model can be a useful tool in improving near-surface temperature forecasts and diagnostics over complex terrain areas.

• 한국수소및신에너지학회논문집
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• 제33권4호
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• pp.419-429
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• 2022

Effects of operating variables on temperature profile and performance of 3 MWth chemical looping combustion system were estimated by mass and energy balance analysis based on configuration and dimension of the system determined by design tool. Air reactor gas velocity, fuel reactor gas velocity, solid circulation rate, and solid input percentage to fluidized bed heat exchanger were considered as representative operating variables. Overall heat output and oxygen concentration in the exhaust gas from the air reactor increased but temperature difference decreased as air reactor gas velocity increased. Overall heat output, required solid circulation rate, and temperature difference increased as fuel reactor gas velocity increased. However, overall heat output and temperature difference decreased as solid circulation rate increased. Temperature difference decreased as solid circulation rate through the fluidized bed heat exchanger increased. Effect of each variables on temperature profile and performance can be determined and these results will be helpful to determine operating range of each variable.

• 문화기술의 융합
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• 제10권2호
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• pp.525-530
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• 2024

환경정보를 실시간으로 획득하여 정보를 제공하는 환경 모니터링 시스템 필요성이 확대되고 있다. 특히 공공수역 수질관리의 경우 법적으로 수동측정과 자동측정을 통해 상시 관리를 진행해야 하며, 대기오염도 탄소중립 실현과 연관하여 미세먼지, 배기가스 저감을 위한 상시 측정 및 관리가 필요한 실정이다. 본 연구에서는 수질오염 및 대기오염 정보를 실시간으로 측정하여 모니터링을 할 수 있는 시스템을 구현하였다. 측정을 위한 도구로 육상과 수상을 동시에 이동 가능한 호버크래프트를 활용하였다. 호버크래프트 본체에 수질측정 및 대기오염측정 센서를 장착하고 그 정보를 실시간으로 모니터링 시스템으로 전송할 수 있는 통신 모듈을 장착하였다. 환경측정용 호버크래프트의 구조를 설계하였으며, 실시간 정보전달 통신 모듈로는 저전력 장거리 통신이 가능한 LoRa 모듈을 적용하였다. 실제 하드웨어 구현을 통해 제안한 시스템의 동작 성능을 확인하였다.