• Journal of Positioning, Navigation, and Timing
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• 제5권2호
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• pp.75-85
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• 2016

The performance of up-to-date mapping functions and various mean temperature equations were analyzed to derive optimal mapping function and mean temperature equation when GNSS precipitable water vapor (PWV) was investigated in the Korean Peninsula. Bernese GNSS Software 5.2, which can perform high precision GNSS data processing, was used for accurate analysis, and zenith total delay (ZTD) required to calculate PWV was estimated via the Precise Point Positioning (PPP) method. GNSS, radiosonde, and meteorological data from 2009 to 2014 were acquired from Sokcho Observatory and used. ZTDs estimated by applying the global mapping function (GMF) and Vienna mapping function 1 (VMF1) were compared with each other in order to evaluate the performance of the mapping functions. To assess the performance of mean temperature equations, GNSS PWV was calculated by using six mean temperature equations and a difference with radiosonde PWV was investigated. Conclusively, accuracy of data processing was improved more when using VMF1 than using GMF. A mean temperature equation proposed by Wu (2003) had the smallest difference with that in the radiosonde in the analysis including all seasons. In summer, a mean temperature equation proposed by Song & Grejner-Brzezinska (2009) had the closest results with that of radiosonde. In winter, a mean temperature equation proposed by Song (2009) showed the closest results with that of radiosonde.

• Journal of Positioning, Navigation, and Timing
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• 제3권4호
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• pp.143-147
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• 2014

The mean temperature is one of the key parameters in computing Precipitable Water Vapor (PWV) from Global Positioning System (GPS) measurements and is usually derived as a function of surface temperature through the use of a mean temperature equation (MTE). In this study, two new types of MTEs were developed as functions solely of the observation time so that the mean temperature can be obtained without surface temperature measurements. To validate the new models, we created one-year time series of GPS-derived PWV using the new MTEs and compared them with the radiosonde-observed PWV. The bias and root-mean-square error were on the other of ~1 mm and ~2 mm, respectively.

• 대한기계학회논문집
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• 제7권4호
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• pp.451-460
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• 1983

Computational four-equation turbulence model is developed and is applied to predict twodimensional unsteady thermal surface discharge into a reservoir. Turbulent stresses and heat fluxes in the momentum and energy equations are determined from transport equations for the turbulent kinetic energy (R), isotropic rate of kinetic energy dissipation (.epsilon.), mean square temperature variance (theta. over bar $^{2}$), and rate of destruction of the temperature variance (.epsilon. $_{\theta}$). Computational results by four-equation model are favorably compared with those obtained by an extended two-equation model. Added advantage of the four-equation model is that it yields quantitative information about the ratio between the velocity time scale and the thermal time scale and more detailed information about turbulent structure. Predicted time scale ratio is within experimental observations by others. Although the mean velocity and temperature fields are similarly predicted by both models, it is found that the four-equation model is preferably candidate for prediction of highly buoyant turbulent flows.

• 한국측량학회지
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• 제30권6_2호
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• pp.615-622
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• 2012

Since the accuracy of precipitable/integrated water vapor estimates from GNSS measurements is proportional to the accuracy of water vapor Weighted Mean Temperature Model (WMTM), the WMTM is a significant formulation in the retrieval of precipitable water vapor from zenith wet delay of GNSS signal. The purpose of this paper is to develop available the WMTM to apply for GNSS meteorology in the region of Algeria, by using the Algerian radiosonde network in the World Meteorological Organization (WMO). It can be concluded that the available GNSS precipitable water vapor which is retrieved by the developed Algerian Weighted Mean Temperature Equation (AWMTE) can be useful technique for sensing of water vapor in the Algeria, after Algerian Continuously Operating Reference System (CORS) will be constructed.

• Asian Journal of Atmospheric Environment
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• 제9권3호
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• pp.214-221
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• 2015

This study considers mean skin temperature to calculate expected temperature using the new heat balance model because the skin temperature is the most important element affecting the heat balance outdoors. For this, we measured the skin temperature in high temperature condition of Korea and applied it to calculate the expected temperature. The calculated expected temperature is compared with the result calculated using previous models which use the estimated mean skin temperature by considering metabolic rate only. Results show that the expected temperatures are higher when measured mean skin temperature is applied to the model, compared to the expected temperature calculated by applying mean skin temperature data calculated using metabolic rate like previous models. The observed mean skin temperature was more suitable for outside conditions and expected temperature is underestimated when mean skin temperature calculated by the equation using metabolic rate is used. The model proposed in this study has a few limitations yet, but it can be applied in various ways to facilitate practical responses to extreme heat.

• 농업과학연구
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• 제38권1호
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• pp.129-143
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• 2011

In this study, to select the incoming solar radiation equation which is most suitable for the estimation of Penman evaporation, 12 incoming solar radiation equations were selected. The Penman evaporation rates were estimated using 12 selected incoming solar radiation equations, and the estimated Penman evaporation rates were compared with measured pan evaporation rates. The monthly average daily meteorological data measured from 17 meteorological stations (춘천, 강능, 서울, 인천, 수원, 서산, 청주, 대전, 추풍령, 포항, 대구, 전주, 광주, 부산, 목포, 제주, 진주) were used for this study. To evaluate the reliability of estimated evaporation rates, mean absolute bias error(MABE), root mean square error(RMSE), mean percentage error(MPE) and Nash-Sutcliffe equation were applied. The study results indicate that to estimate pan evaporation using Penman evaporation equation, incoming solar radiation equation using meteorological data such as precipitation, minimum air temperature, sunshine duration, possible duration of sunshine, and extraterrestrial radiation are most suitable for 11 study stations out of 17 study stations.

• 생물환경조절학회지
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• 제17권2호
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• pp.124-131
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• 2008

본 연구에서는 감 재배지 간 과실 특성 차이에 관계한 기온 요인을 분석하고자 8개 단감 '부유' 재배지의 16개 기온요인과 과실 특성을 조사하여 주성분 및 다중회귀 분석을 실시하였다. 16개 기온요인 중 제1주성분은 12개 요인으로 이중 연 평균최저기온, 10월 평균기온, 연 평균최저극온, 생육기 평균기온의 영향력이 아주 높았다. 그리고 제2주성분은 4개 요인으로 4월에서 7월까지의 월 평균기온이었고 5월과 6월 평균기온의 영향력이 높았다. 이에 제2주성분까지 누적기여율은 91.4%로 재배지 간 기온 차이에 관여하는 기온 요인을 분석하는 데에는 충분하였다. 8개 재배지 중 5 재배지은 주요 기온요인이나 그 영향력에서 뚜렷한 차이를 나타내었다. 기온요인과 과실 특성 간 다중회귀분석에서 과고는 생육기 평균기온($X_8$) 겨울철 적산온도($X_6$) 영향을 뚜렷이 받으며 회귀식 $Y=150.55-5.375X_8+0.014X_6$을 나타내었고, 이 회귀식에 대하여 생육기 평균최저기온($X_9$), 적산온도($X_5$), 8월 평균기온($X_{12}$) 등이 영향을 주었다. 과경은 생육기 평균기온($X_8$, 부의 상관), 과육갈반정도는 생육기 평균최저기온($X_9$, 정의 상관), 과피색 $a^*$값은 연 평균최저기온($X_2$, 정의 상관)의 영향을 받는 것으로 나타났다.

• Journal of Astronomy and Space Sciences
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• 제23권4호
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• pp.373-384
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• 2006

현재 GPS 가강수량 관련 연구에는 대부분 Bevis 평균온도식을 사용하고 있다. 그러나 Bevis 평균온도식은 북미대륙의 기상관측 자료를 이용하여 개발된 것이므로 기후조건이 다른 우리나라에 적용할 경우 가강수량 산출이 부정확할 수 있다. 이 연구에서는 우리나라 기상관측 자료를 이용하여 한반도 기상조건에 적합한 평균온도식을 개발하고, 이 개발된 평균온도식을 적용하여 가강수량을 산출한 후 Bevis 평균온도식과 기존 국내 연구에서 개발된 평균온도식을 이용한 가강수량과 비교하였다. 그 결과 각 평균온도식에 따른 가강수량은 이 연구에서 개발한 평균온도식을 기준으로 했을 때 지상기온이 높을 경우에 차이가 증가하며, 최대 $1{\sim}3mm$의 RMS 차이가 발생함을 알 수 있었다.

• Journal of Biosystems Engineering
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• 제25권6호
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• pp.497-502
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• 2000

For the analysis of geothermal energy utilization in agriculture the relations between soil temperature and geographical variables such as latitude longitude and sea level in Korea were analyzed and the regression equations were suggested among them. The measured soil temperature data for four years in eighteen cities were used to get the soil temperature fitting equation depending on the soil depth and the time of year in each city. The mean correlation coefficient for those data fitting was 0.980. the correlation coefficient of regression analysis for the mean soil temperature($T_{m}$) on the geographical variables such as latitude longitude and height above sea level was 0.958 and those for soil surface temperature amplitude(Tss) and phase constant(tp) were 0.889, 0.835, respectively. The relation between the apparent thermal diffusivity of the soil and the three geographical variables was not significant. The regression equations for the mean soil temperature($T_{m}$) soil surface temperature amplitude(Tss) and phase constant(tp) adopting latitude($X_{1}$) longitude($X_2$) height above sea level($X_3$) were as follows : $T_{m}$=50.049 - $0.849X_1$-$0.03131X_2$-$0.00622X_3$Tss=-6.970 +$0.584X_1$+$0.00530X_2$-$0.00214X_3$tp=70.353 - $1.404X_1$+ $0.02098X_2$+ $0.00312X_3$

• 대한기계학회논문집B
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• 제23권2호
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• pp.243-253
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• 1999

The dual reciprocity boundary element method (DRBEM) is used to solve the Graetz problem of laminar flow inside circular duct. In this method the domain integral tenn of boundary integral equation resulting from source term of governing equation is transformed into equivalent boundary-only integrals by using the radial basis interpolation function, and therefore complicate domain discretization procedure Is completely removed. Velocity profile is obtained by solving the momentum equation first and then, using this velocities as Input data, energy equation Is solved to get the temperature profile by advancing from duct entrance through the axial direction marching scheme. DRBEM solution is tested for the uniform temperature and heat flux boundary condition cases. Local Nusselt number, mixed mean temperature and temperature profile inside duct at each dimensionless axial location are obtained and compared with exact solutions for the accuracy test Solutions arc in good agreement at the entry region as well as fully developed region of circular duct, and their accuracy are verified from error analysis.