• Title/Summary/Keyword: NEE

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The Application Tendency of Western Classic Style Appeared to Residencial Space Interior Composition Elements (주거공간 실내구성요소에 나타난 서양 고전양식의 적용경향)

  • 오혜경;이지현
    • Archives of design research
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    • v.13 no.4
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    • pp.115-123
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    • 2000
  • The purpose of this study was to examine the application tendency about the interior elements of the western classical style which appears in Korean residential space. The examined objects were 324 pictures of 99 residential spaces from the different monthly magazines between Sep.1994 to Sep.1999. The results of this study were as follows: 1. The tendency of application according to the kind of space, it has appeared much in Iivingroom, master bedroom and dining room of apartments and houses. As for the single application in residential space, Rococo and Neo-Classic style was shown most, and the cases applied through the mixture of Renaissance style and Nee-classic style appeared most. 2. The tendency of application arroding to the interior elements of space, the wall of Nee-Classic style and the ceiling of Renaissance style, the window and door of Nee-classic style, and the furniture of Rococo style were being applied much.

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$CO_2$ and Water Vapor Flux Measurement by Eddy Covariance Method in a Paddy Field in Korea (한반도 논에서의 에디공분산 방법에 의한 $CO_2$와 수증기 플럭스 관측)

  • Lee Jeongtaek;Lee Yangsoo;Kim Gunyeob;Shim Kyomoon
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.7 no.1
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    • pp.45-50
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    • 2005
  • This study was conducted to measure and understand the exchange of CO₂ and water in a rice canopy. Eddy covariance system was installed on a 10m tower along with other meteorological instruments. CO₂ flux and surface energy balance were measured throughout the whole growing season in 2003 over a typical paddy field in Icheon, Korea. During the early growth stage in May and June, most of net radiation was partitioned to latent heat flux with daytime Bowen ratio of 0.3 to 0.7. Evapotranspiration (i.e., daily integrated latent heat flux) typically ranged from 3 to 4 mm d/sup -1/, with even higher rates on sunny days. Daily integrated net ecosystem exchange (NEE) of CO₂ increased with increasing solar radiation and leaf area index (LAI). The NEE was especially high during the stages of young panicle formation and heading. On 1 June 2003, when the rice field was flooded, it was a weak sink of atmospheric CO₂ with an uptake rate of 9.1 gm/sup -2/d/sup -1/. Despite frequent rainy and cloudy conditions in summer, maximum NEE of 36.2 gm/sup -2/d/sup -1/ occurred on 31 July prior to heading stage. As rice crop senesced after early September, the NEE decreased.

Traffic-Aware Relay Sleep Control for Joint Macro-Relay Network Energy Efficiency

  • Deng, Na;Zhao, Ming;Zhu, Jinkang;Zhou, Wuyang
    • Journal of Communications and Networks
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    • v.17 no.1
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    • pp.47-57
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    • 2015
  • With the ever growing demand of data applications, the joint macro-relay networks are emerging as a promising heterogeneous deployment to provide coverage extension and throughput enhancement. However, the current cellular networks are usually designed to be performance-oriented without enough considerations on the traffic variation, causing substantial energy waste. In this paper, we consider a joint macro-relay network with densely deployed relay stations (RSs), where the traffic load varies in both time and spatial domains. An energy-efficient scheme is proposed to dynamically adjust the RS working modes (active or sleeping) according to the traffic variations, which is called traffic-aware relay sleep control (TRSC). To evaluate the performance of TRSC,we establish an analytical model using stochastic geometry theory and derive explicit expressions of coverage probability, mean achievable rate and network energy efficiency (NEE). Simulation results demonstrate that the derived analytic results are reasonable and the proposed TRSC can significantly improve the NEE when the network traffic varies dynamically.

Analysis of Bulk Concentration on Double-Layer Structure for Electrochemical Capacitors

  • Khaing, Khaing Nee Nee;Hla, Tin Tin
    • Korean Journal of Materials Research
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    • v.32 no.7
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    • pp.313-319
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    • 2022
  • Double-layer capacitors (DLCs) are developed with high surface electrodes to achieve a high capacitance value. In the present work, the initial bulk concentration of 1 mol/m3 and 3 mol /m3 are selected to show the consequential effects on the performance of a double-layer capacitor. A 1D model of COMSOL Multiphysics has been developed to analyze the electric field and potential in cell voltage, the electric displacement field and polarization induced by the field, and energy density in a double-layer structure. The electrostatics and the electric circuit modes in COMSOL are used to simulate the electrochemical processes in the double-layer structure. The analytical analysis of a double-layer capacitor with different initial bulk concentrations is investigated by using Poisson-Nernst-Plank equations. From the simulation results, the differential capacitance changes as a function of compact layer thickness and initial bulk concentration. The energy density varies with the differential capacitance and voltage window. The values of energy density are dominated by the interaction of ions in the solution and electrode surface.

Errors in Net Ecosystem Exchanges of CO2, Water Vapor, and Heat Caused by Storage Fluxes Calculated by Single-level Scalar Measurements Over a Rice Paddy (단일 높이에서 관측된 저장 플럭스를 사용할 때 발생하는 논의 이산화탄소, 수증기, 현열의 순생태계교환량 오차)

  • Moon, Minkyu;Kang, Minseok;Thakuri, Bindu Malla;Lee, Jung-Hoon
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.17 no.3
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    • pp.227-235
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    • 2015
  • Using eddy covariance method, net ecosystem exchange (NEE) of $CO_2$ ($F_{CO_2}$), $H_2O$ (LE), and sensible heat (H) can be approximated as the sum of eddy flux ($F_c$) and storage flux term ($F_s$). Depending on strength and distribution of sink/source of scalars and magnitude of vertical turbulence mixing, the rates of changes in scalars are different with height. In order to calculate $F_s$ accurately, the differences should be considered using scalar profile measurement. However, most of flux sites for agricultural lands in Asia do not operate profile system and estimate $F_s$ using single-level scalars from eddy covariance system under the assumption that the rates of changes in scalars are constant regardless of the height. In this study, we measured $F_c$ and $F_s$ of $CO_2$, $H_2O$, and air temperature ($T_a$) using eddy covariance and profile system (i.e., the multi-level measurement system in scalars from eddy covariance measurement height to the land surface) at the Chengmicheon farmland site in Korea (CFK) in order to quantify the differences between $F_s$ calculated by single-level measurements ($F_s_{-single}$ i.e., $F_s$ from scalars measured by profile system only at eddy covariance system measurement height) and $F_s$ calculated by profile measurements and verify the errors of NEE caused by $F_s_{-single}$. The rate of change in $CO_2$, $H_2O$, and Ta were varied with height depending on the magnitudes and distribution of sink and source and the stability in the atmospheric boundary layer. Thus, $F_s_{-single}$ underestimated or overestimated $F_s$ (especially 21% underestimation in $F_s$ of $CO_2$ around sunrise and sunset (0430-0800 h and 1630-2000 h)). For $F_{CO_2}$, the errors in $F_s_{-single}$ generated 3% and 2% underestimation of $F_{CO_2}$ during nighttime (2030-0400 h) and around sunrise and sunset, respectively. In the process of nighttime correction and partitioning of $F_{CO_2}$, these differences would cause an underestimation in carbon balance at the rice paddy. In contrast, there were little differences at the errors in LE and H caused by the error in $F_s_{-single}$, irrespective of time.

Standardization of KoFlux Eddy-Covariance Data Processing (KoFlux 에디 공분산 자료 처리의 표준화)

  • Hong, Jin-Kyu;Kwon, Hyo-Jung;Lim, Jong-Hwan;Byun, Young-Hwa;Lee, Jo-Han;Kim, Joon
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.11 no.1
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    • pp.19-26
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    • 2009
  • The standardization of eddy-covariance data processing is essential for the analysis and synthesis of vast amount of data being accumulated through continuous observations in various flux measurement networks. End users eventually benefit from the open and transparent standardization protocol by clear understanding of final products such as evapotranspiration and gross primary productivity. In this paper, we briefly introduced KoFlux efforts to standardize data processing methodologies and then estimated uncertainties of surface fluxes due to different processing methods. Based on our scrutiny of the data observed at Gwangneung KoFlux site, net ecosystem exchange and ecosystem respiration were sensitive to the selection of different processing methods. Gross primary production, however, was consistent within errors due to cancellation of the differences in NEE and Re, emphasizing that independent observation of ecosystem respiration is required for accurate estimates of carbon exchange. Nocturnal soil evaporation was small and thus the annually integrated evapotranspiration was not sensitive to the selection of different data processing methods. The implementation of such standardized data processing protocol to AsiaFlux will enable the establishment of consistent database for validation of models of carbon cycle, dynamic vegetation, and land-atmosphere interaction at regional scale.

Estimation of Net Biome Production in a Barley-Rice Double Cropping Paddy Field of Gimje, Korea (김제 보리-벼 이모작지에서의 순 생물상생산량의 추정)

  • Shim, Kyo-Moon;Min, Sung-Hyun;Kim, Yong-Seok;Jung, Myung-Pyo;Choi, In-Tae
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.17 no.2
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    • pp.173-181
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    • 2015
  • Fluxes of carbon dioxide ($CO_2$) were measured above crop canopy using the Eddy Covariance (EC) method, and emission rate of methane ($CH_4$) was measured using Automatic Open/Close Chamber (AOCC) method during the 2012-2013 barley and rice growing season in a barley-rice double cropping field of Gimje, Korea. The net ecosystem exchange (NEE) of $CO_2$ in the paddy field was analyzed to be affected by crop growth (biomass, LAI, etc.) and environment (air temperature, solar radiation, etc.) factors. On the other hand, the emission rate of $CH_4$ was estimated to be affected by water management (soil condition). NEE of $CO_2$ in barley, rice and fallow period was -100.2, -374.1 and $+41.2g\;C\;m^{-2}$, respectively, and $CH_4$ emission in barley and rice period was 0.2 and $17.3g\;C\;m^{-2}$, respectively. When considering only $CO_2$, the barley-rice double cropping ecosystem was estimated as a carbon sink ($-433.0g\;C\;m^{-2}$). However, after considering the harvested crop biomass ($+600.3g\;C\;m^{-2}$) and $CH_4$ emission ($+17.5g\;C\;m^{-2}$), it turned into a carbon source ($+184.7g\;C\;m^{-2}$).

Seasonal Variation of Carbon Dioxide and Energy Fluxes During the Rice Cropping Season at Rice-barley Double Cropping Paddy Field of Gimje (김제 벼-보리 이모작 논에서 벼 재배기간동안의 CO2 및 에너지 플럭스의 계절적 변화)

  • Min, Sung-Hyun;Shim, Kyo-Moon;Kim, Yong-Seok;Jung, Myung-Pyo;Kim, Seok-Cheal;So, Kyu-Ho
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.15 no.4
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    • pp.273-281
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    • 2013
  • Based on the results of continuous flux measurements at the Gimje paddy flux site in the southwestern coast of Korea, carbon dioxide and energy exchanges between customarily cultivated rice-barley double cropping paddy field and the atmosphere during the 2012 rice growing season (from $9^{th}$ Jun. 2012 through $20^{th}$ Oct. 2012) were analyzed. Carbon dioxide and energy (H, LE) fluxes were estimated by the eddy covariance method. Environmental parameters (net radiation, precipitation, etc.) and plant biomass (LAI, plant height, etc.) were measured along with fluxes. After the quality control and gap-filling, the observed fluxes were analyzed. The results have been showed that net ecosystem exchange (NEE), gross primary production (GPP), and ecosystem respiration (Re) during the rice cropping period were -277.1, 710.3, and 433.2 g C $m^{-2}$, respectively.