• 한국농림기상학회지
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• 제1권1호
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• pp.52-59
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• 1999

Vegetation canopy plays an important role in $CO_2$/$H_2$O exchange between the biosphere and the atmosphere by controlling leaf stomata. In this study, rice (Oryza sativa L.), a staple crop in Asia was investigated to formulate its single leaf model of photosynthesis and stomatal conductance. Photosynthesis and stomatal conductance were measured with a portable infrared gas analyzer system. Other plant and meteorological variables were also measured. To evaluate empirical constants in this biochemical leaf model, nonlinear least squares technique was used. The maximum catalytic activity of enzyme and the maximum rate of electron transport were $ 100\mu$㏖ $m^{-2}$ $s^{-1}$ and $140 \mu$㏖ m$^{-2}$ s$^{-1}$ (@ 35$^{\circ}C$), respectively. The empirical constants, m and b, associated with stomatal conductance model were 9.7 and $0.06 m^{-2}$ $s^{-1}$ , respectively. On a leaf scale, agreements between the modeled and the measured values of photosynthesis and stomatal conductance were on average within 20%, and the simulation of diurnal variation was also satisfactory On a canopy scale, the Simple Biosphere model(SiB2) was tested using the derived parameters. The modeled energy fluxes were compared against the micrometeorologically measured fluxes over a rice canopy. Agreements between the modeled and the measured values of net radiation, sensible heat and latent heat fluxes, and $CO_2$ flux (i.e., net canopy photosynthesis) were on average within 25%.

• 대기
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• 제34권1호
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• pp.69-81
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• 2024

In this paper, Annual flux variations in the Boseong Tall Tower (BTT) from 2016 to 2020 were analyzed using data from three levels (2.5 m, 60 m, and 300 m). BTT was installed in Boseong-gun, Jeollanam-do in February 2014 and continued to conduct energy exchange observations such as CO2, sensible heat, and latent heat using the eddy covariance method until March 2023. The BTT was located in a very flat and uniform paddy field, and flux observations were conducted at four levels: 2.5 m, 60 m, 140 m, and 300 m above ground. Surface energy balance was confirmed from observed data of net radiation flux, soil heat flux, sensible heat flux, and latent heat flux. Additionally, 2.5 m height surface fluxes, which are most influenced by agricultural land, were compared with data from Local Data Assimilation and Prediction System (LDAPS) of the Korea Meteorological Administration to evaluate the accuracy of LDAPS flux data. The correlation coefficient between LDAPS flux data and observed values was 0.95 or higher. Excluding summer latent heat flux data, there was a general tendency for LDAPS data to be higher than observed values. The footprint areas estimated below 60 m height mainly covered agricultural land, and flux observations at 2.5 m and 60 m heights showed typical agricultural characteristics. In contrast, the footprint estimated at 300 m height did not show agricultural characteristics, indicating that observations at this height encompassed a wide range, including mountains, sea, and roads. The analysis results of long-term flux observations can contribute to understanding the energy and carbon dioxide fluxes in agricultural fields. Furthermore, these results can be utilized as essential data for validating and improving numerical models related to such fluxes.

• 천문학회지
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• 제51권4호
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• pp.111-117
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• 2018

A numerical method is proposed to calculate the response of detectors measuring particle energies from incident isotropic fluxes of electrons and positive ions. The isotropic flux is generated by injecting particles moving radially inward on a hypothetical, spherical surface encompassing the detectors. A geometric projection of the field-of-view from the detectors onto the spherical surface allows for the identification of initial positions and momenta corresponding to the clear field-of-view of the detectors. The contamination of detector responses by particles penetrating through, or scattering off, the structure is also similarly identified by tracing the initial positions and momenta of the detected particles. The relative contribution from the contaminating particles is calculated using GEANT4 to obtain the geometric factor of the instrument as a function of the energy. This calculation clearly shows that the geometric factor is a strong function of incident particle energies. The current investigation provides a simple and decisive method to analyze the instrument geometric factor, which is a complicated function of contributions from the anticipated field-of-view particles, together with penetrating or scattered particles.

• 한국지구과학회지
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• 제39권1호
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• pp.1-22
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• 2018

Eight different data sets are examined in order to gain insight into the surface heat flux traits of the East Asian marginal seas. In the case of solar radiation of the East Sea (Japan Sea), Coordinated Ocean-ice Reference Experiments ver. 2 (CORE2) and the Objectively Analyzed Air-Sea Fluxes (OAFlux) are similar to the observed data at meteorological stations. A combination is sought by averaging these as well as the Climate Forecast System Reanalysis (CFSR) and the National Centers for Environmental Prediction (NCEP)-1 data to acquire more accurate surface heat flux for the East Asian marginal seas. According to the Combination Data, the annual averages of net heat flux of the East Sea, Yellow Sea, and East China Sea are -61.84, -22.42, and $-97.54Wm^{-2}$, respectively. The Kuroshio area to the south of Japan and the southern East Sea were found to have the largest upward annual mean net heat flux during winter, at -460- -300 and at $-370--300Wm^{-2}$, respectively. The long-term fluctuation (1984-2004) of the net heat flux shows a trend of increasing transport of heat from the ocean into the atmosphere throughout the study area.

• Nuclear Engineering and Technology
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• 제38권5호
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• pp.411-416
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• 2006

The Advanced Test Reactor (ATR), at the Idaho National Laboratory (INL), is one of the world's premier test reactors for providing the capability for studying the effects of intense neutron and gamma radiation on reactor materials and fuels. The physical configuration of the ATR, a 4-leaf clover shape, allows the reactor to be operated at different power levels in the comer 'lobes' to allow for different testing conditions for multiple simultaneous experiments. The combination of high flux (maximum thermal neutron fluxes of 1E15 neutrons per square centimeter per second and maximum fast [E>1.0 MeV] neutron fluxes of 5E14 neutrons per square centimeter per second) and large test volumes (up to 122 cm long and 12.7 cm diameter) provide unique testing opportunities. The current experiments in the ATR are for a variety of test sponsors - US government, foreign governments, private researchers, and commercial companies needing neutron irradiation services. There are three basic types of test configurations in the ATR. The simplest configuration is the sealed static capsule, which places the capsule in direct contact with the primary coolant. The next level of experiment complexity is an instrumented lead experiment, which allows for active control of experiment conditions during the irradiation. The most complex experiment is the pressurized water loop, in which the test sample can be subjected to the exact environment of a pressurized water reactor. For future research, some ATR modifications and enhancements are currently planned. This paper provides more details on some of the ATR capabilities, key design features, experiments, and future plans.

• 대기
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• 제20권4호
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• pp.519-530
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• 2010

In this paper we review current research on Atmospheric Brown Clouds (ABCs) with lightweight Unmanned Aerial Vehicles (UAVs) and miniaturized instruments. The UAV technology for in-situ measurements, including aerosol concentration, aerosol size distribution, aerosol absorption, cloud drop size distribution, solar radiation fluxes (visible and broadband), and spectral radiative fluxes, is a leading-edge technology for cost-effective atmospheric sounding, which can fill the gap between the ground measurement and satellite observation. The first experimental observation with UAVs in Korea, Cheju ABC Plume Monsoon Experiment (CAPMEX), conducted during summer 2008 revealed that the Beijing plumes exerted a strong positive influence on the net warming and fossil-fuel-dominated black-carbon plumes were approximately 100% more efficient warming agents than biomass-burning-dominated plumes. Long-term sustainable routine UAV measurements will eventually provide truly three-dimensional data of ABCs, which is necessary for the better understanding of their climate impacts and for the improvement of numerical models for air pollution, weather forecast and climate change.

• 천문학회지
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• 제47권6호
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• pp.201-207
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• 2014

We report the development of solar flux receivers operating at 2.8 GHz to monitor solar radio activity. Radio waves from the sun are amplified, filtered, and then transmitted to a power meter sensor without frequency down-conversion. To measure solar flux, a calibration scheme is designed with a noise source, an ambient load, and a hot load at $100^{\circ}C$. The receiver is attached to a 1.8 m parabolic antenna in Icheon, owned by National Radio Research Agency, and observation is being conducted during day time on a daily basis. We compare the solar fluxes measured for last seven months with solar fluxes obtained by DRAO in Penticton, Canada, and by the Hiraiso solar observatory in Japan, and finally establish equations to convert observed flux to the so-called Penticton flux with an accuracy better than 3.2 sfu.

• The Korean Journal of Ecology
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• 제23권1호
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• pp.39-43
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• 2000

1996년 7월 하순부터 9월 하순에 걸쳐 동경농공대학 농학부 부속부중농장(동경도 부중시)의 대두(Glycine max)개체군을 대상으로 미기상학적 플럭스측정방법의 하나인 열수지법을 이용하여 CO₂ 플럭스와 O₃ 플럭스를 측정하였다. CO₂ 플럭스와 O₃ 플럭스는 엽면적지수(LAI)의 변화에 영향을 받았으며, LAI가 2.0이상일 경우 CO₂ 플럭스는 광합성유효발사량(PAR)과 정비례관계가 있었다. O₃ 플럭스는 측정 기간 중 항상 양의 수치를 나타냈으며, 평균치는 0.5 mol m/sup -2/S/sup -1/이었다. 또한 CO₂와 O₃ 침착속도사이에는 정비례관계가 있었다 (LAI>2.0).

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권1호
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• pp.41-56
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• 1999

Since UV-B radiation measuring networks have not been established, numerical models which calculate the flux from other readily available meteorological measurements may play an important role. That is, such a problem can be solved by using parameterization models such as two stream approximation, the delta-Eddington method, doubling method, and discrete ordinate method. However, most UV-B radiative transfer models have not been validated with measurements, because such models are not intended as practical computational schemes for providing surface estimates of UV-B radiation. The main concern so far has been to demonstrate model sensitivity for cloudless skies. In particular, few have been concerned with real cloud information. Clouds and aerosols have generally been incorporated as constituents of particular atmospheric layers with specified optical depths and scattering properties. The parameterization model presented here is a combination of a detailed radiative transfer algorithm for a coludless sky radiative process and a more approximate scheme to handle cloud effects. The model input data requires a daily measurement of the total ozone amount plus a daily record of the amount and type of cloud in the atmosphere. Measurements for an examination of the models at the Department of Atmospheric Sciences, Pusan National University have been takenfrom February, 1995. These models can be used to calculate present and future fluxes where measurements have not been taken, and construct climatologies for the period before ozone depletion began.

• Journal of Astronomy and Space Sciences
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• 제18권2호
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• pp.109-118
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• 2001

1992년에 발사된 우리별 1호는 고에너지 양성자들이 OBC(On-Board Computer)186의 메모리에 SEU(Single Event Upset)을 일으키는 안쪽 반알렌대(Inner Van Allen Radiation Belt) 를 통과한다. 본 논문에서는 Chi-Square 방법을 이용하여 OBC(On-Board Compute.)186 메모리에서 측정된 SEU 데이터와 NASA/NSSDC의 AP-8 양성자 모델을 비교하여, SEU를 유발하게 되는 문턱 에너지를 추정해 보았다. OBC186위치에서의 양성자 선속을 유도하기 위해서 위성체에 의한 차폐 효과가 고려되었으며 모델의 신뢰성을 높이기 위해 태양 활동이 활발한 기간에 얻어진 데이터들은 제거되었다. 비교 결과 우리별 1호 OBC186 주 메모리의 문턱에너지는 $110{pm}10MeV$로 추정 되었다.