• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.5
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• pp.405-412
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• 2015

This paper represents a filter design to estimate the airspeed of a spin-stabilized, trajectory-correctible artillery ammunition. Due to the limited power and space in operational point of view, the airspeed sensor is not installed, and thus the airspeed need to be estimated using limited sensor measurements. The only IMU measurements(three-axis specific forces and angular rates) are used in this application. The extended Kalman filter algorithm is applied since a linear filter can not cover the its wide operational range in airspeed and altitude. In the implementation of the EKF, the state and measurement equations are transformed into the no-roll frame for simple form of Jacobian matrix. The simulation study is conducted to evaluate the performance of the filter under various environment conditions of sensor noise and wind turbulence. In addition, the effect of the choice in filter design parameters, i.e. process error covariance matrices is analyzed on the performance of the estimation of airspeed and angular rates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.183-185
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• 2015

Recently, big data analysis based on machine learning has gained popularity and many machine learning techniques have been applied to the field of agriculture. By using machine learning technique to analyze huge number of samples of biological and environmental data, new observations can be found. In this research, we consider the estimation of proportional daily weight increase (PDWI) based on measurement data from experimental swine farm. In order to derive the exact formulation for PDWI estimation, we have used measured value of mean, daily maximum, daily minimum of temperature, humidity, CO2, wind speed and measured PDWI values. Based on collected data, we have derived equation for PDWI estimation using tree-based algorithm. In the derived formulation, we have found that the daily average temperature is the most dominant factor that affects PDWI. Our results can be applied to pig farms to estimate the PDWI of swine.

• Journal of Science Criminal Investigation
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• v.11 no.3
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• pp.178-185
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• 2017

It is one of the most important factors to statistical estimation of ambient temperature for accumulated degree day (ADD) and minimum postmortem interval (PMI) in the incident scene. Until now, we applied the temperature of the nearest weather stations, adjusted temperature, or estimated the temperature by the linear regression analysis to estimate the temperature of the incident site. At this time, the estimated temperature may be changed according to the method of temperature estimation. And The accuracy of the estimated value may also vary depending on the environmental factors such as capacity, wind speed, humidity, and rainfall, which may affect measurement conditions and temperature. Therefore, we studied the effect of various environmental factors and measurement conditions for ambient temperature in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.210-217
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• 2009

Pollen flow is one of the essential components in the ecological risk assessment of transgenic crops, because pollen can act as a vehicle to disseminate transferred alien genes. Pollen flow pattern of a cultivated rice variety and Living modified (LM) rice was studied at diurnal and distance changes under field. We measured airborne pollen density at the distances of -1, 0.5, 0, 1, 2, 3, 4, 5, 7, 9, 11 and 13 m from rice cultivation and recorded the direction and speed of wind using weather station in the conventional rice paddy field during the flowering period of rice. Diurnal changes in pollen density were observed as a peak between 10:00 to 13:00 hr. The density of airborne rice pollen geometrically decreased with the increase of distance from pollen sources. It is therefore necessary to carry out a detailed investigation of pollen flow of a particular species, where ecological risk assessment requires an accurate estimation of pollen flow including both distance and intensity of pollen dispersal. The rice pollen flow was significantly influenced by weather conditions, particularly by wind direction and speed. The precise determination of the local wind conditions at flowering time therefore appears to be of primary importance for setting up suitable isolation distance from transgenic rice in the field.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.81-87
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• 2004

It includes the considerable concentration and dangerousness as the peculiar work of a pilot and dock-master to berthing/deberthing the big object as for the ship within the port or the ship yard. A tug utilization is getting increased in this berthing/deberthing work and the own ship is affected a lot by external force due to moving with low advance speed. In this study, we constructed the 2 dimension virtual system which can conduct the berthing/deberthing manoeuvring work by using mainly tugs in a external force, particularly strong wind. Also, propose objective standard that could estimate the degree of manoeuvring difficulty, and conducted simulation experiment for this. we analyzed correlations between the subjective estimation which is described numerically the decreased dangerousness and the objective index which is related to the main parameter regarding manoeuvring by using this simulator from the result of conducting simulation experiment. And then we discussed the estimation technique of manoeuvring difficulty.

• Journal of Environmental Impact Assessment
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• v.16 no.1
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• pp.1-13
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• 2007

This study was carried out to estimate the emission reduction rates for the regional allowable emissions by special measures to achieve the target air quality in Seoul Metropolitan Area (SMA). A modeling system was designed to validate the details in enforcement regulations set up by local governments based on the current status and plans for air quality improvement. Modeling system was composed of meteorological model (MM5), emission model (SMOKE), and air quality model (CMAQ). Predicted results by this system show quiet well not only daily air pollutants concentration but also the tendencies of wind direction, wind speed and temperature. To achieve the target air quality in Seoul Metropolitan Area (SMA), emission allowances are estimated by seasons and regions. Referring to the base year 2002, it was estimated that emission reduction rates to achieve the intermediate goal in 2007 were 14.2% and 16.6% for NOx and $PM_{10}$, respectively. It was also estimated that 52% of NOx and 48% of $PM_{10}$ reductions from the base year 2002 would be required to accomplish the air quality improvement goal of 22 ppb for $NO_2$, and $40mg/m^3$ for $PM_{10}$ in year 2014. To improve $NO_2$ and $PM_{10}$ concentration through emissions reduction policies, it was found that emissions reduction for the on-road mobile sources would be the most effective in SMA.

• Journal of Korea Water Resources Association
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• v.50 no.1
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• pp.37-53
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• 2017

Pan evaporation has been used as an indirect method for the estimation of reservoir evaporation. Therefore, in this study, pan evaporation estimation equations using only temperature data were suggested in the case that available meteorological data is limited. A formula for estimating the pan evaporation were suggested by comparing estimated pan evaporation with measured pan evaporation in 12 study areas in Korea. The suggested pan evaporation equations were verified in 44 study areas by comparing not only with temperature-based equations but also with equations using other meteorological data (temperature, wind speed, relative humidity, and sunshine duration). The study results indicate that the suggested equations in this study provide much better pan evaporation estimates, compared with other temperature-based equations. Overall, the suggested equations provide appropriate pan evaporation estimates in most of 56 study areas. Therefore, the suggested equations using only temperature data in this study are considered appropriate for the estimation of pan evaporation in Korea especially in the case that available meteorological data is limited. In the future, using the air temperature and pan evaporation data measured at the reservoir, further research is needed to examine the applicability of suggested equations for the estimation of reservoir evaporation.

• Journal of Environmental Science International
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• v.26 no.6
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• pp.741-750
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• 2017

A model coupling a meteorological predictive model and a vegetation photosynthesis and respiration model was used to simulate $CO_2$ concentrations over coastal basin areas, and modeling results were estimated with aircraft observations during a massive sampling campaign. Along with the flight tracks, the model captured the meteorological variables of potential temperature and wind speed with mean bias results of $0.8^{\circ}C$, and 0.2 m/s, respectively. These results were statistically robust, which allowed for further estimation of the model's performance for $CO_2$ simulations. Two high-resolution emission data sets were adopted to determine $CO_2$ concentrations, and the results show that the model underestimated by 1.8 ppm and 0.9 ppm at higher altitude over the study areas during daytime and nighttime, respectively, on average. Overall, it was concluded that the model's $CO_2$ performance was fairly good at higher altitude over the study areas during the study period.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.1
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• pp.41-53
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• 2015

This study was performed to assess the level of ozone risk for wheat in the central region of the Korean Peninsula by using two ozone indices, the ozone-concentration based index (AOT40) and the ozone-flux based index ($AF_{st}Y$), and to analyze the relationship between the two indices. In the present study for $AF_{st}Y$ calculation, the Monin-Obukhov length was estimated using the Pasquill stability class which was determined from routine meteorological data such as wind speed, solar radiation and cloudiness. The AOT40 and $AF_{st}6$ indices were calculated for wheat at 3 sites in the central region of the Korean Peninsula during a period of 3 months from April 1 to June 30, 2006. It should be noted that the estimation of ozone index $AF_{st}6$ in this study was performed under several assumptions. The results for both indices, AOT40 and $AF_{st}6$, showed that agricultural crops could be seriously damaged by ozone in the local region of the Korean Peninsula.

• Atmosphere
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• v.25 no.2
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• pp.193-203
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• 2015

A large aperture scintillometer (LAS) was deployed with an optical path length of 2.1 km to estimate turbulent sensible heat flux (${\mathcal{Q}}_H$) over a highly heterogeneous urban area. Scintillation measurements were conducted during cold season in November and December 2013, and the daytime data of 14 days were used in the analysis after quality control processes. The LAS-derived ${\mathcal{Q}}_H$ show reasonable temporal variation ranging $20{\sim}160W\;m^{-2}$ in unstable atmospheric conditions, and well compare with the measured net radiation. The LAS footprint analysis suggests that ${\mathcal{Q}}_H$ can be relatively high when the newly built-up urban area has high source contribution of the turbulent flux in the study area ('northwesterly winds'). Sensitivity tests show that the LAS-derived ${\mathcal{Q}}_H$ are highly sensitive to non-dimensional similarity function for temperature structure function parameter, but relatively less sensitive to surface aerodynamic parameters and meteorological variables (temperature and wind speed). A lower Bowen ratio also has a significant influence on the flux estimation. Overall uncertainty of the estimated daytime ${\mathcal{Q}}_H$ is expected within about 20% at an upper limit for the analysis data. It is also found that stable atmospheric conditions can be poorly determined when the scintillometry technique is applied over the highly heterogeneous urban area.