• Communications for Statistical Applications and Methods
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• v.30 no.1
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• pp.95-107
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• 2023

Purpose: The statistical analysis of point processes on linear networks is a recent area of research that studies processes of events happening randomly in space (or space-time) but with locations limited to reside on a linear network. For example, traffic accidents happen at random places that are limited to lying on a network of streets. This paper applies techniques developed for point processes on linear networks and the tools available in the R-package spatstat to estimate the intensity of traffic accidents in Leon County, Florida. Methods: The intensity of accidents on the linear network of streets is estimated using log-linear Poisson models which incorporate cubic basis spline (B-spline) terms which are functions of the x and y coordinates. The splines used equally-spaced knots. Ten different models are fit to the data using a variety of covariates. The models are compared with each other using an analysis of deviance for nested models. Results: We found all covariates contributed significantly to the model. AIC and BIC were used to select 9 as the number of knots. Additionally, covariates have different effects such as increasing the speed limit would decrease traffic accident intensity by 0.9794 but increasing the number of lanes would result in an increase in the intensity of traffic accidents by 1.086. Conclusion: Our analysis shows that if other conditions are held fixed, the number of accidents actually decreases on roads with higher speed limits. The software we currently use allows our models to contain only spatial covariates and does not permit the use of temporal or space-time covariates. We would like to extend our models to include such covariates which would allow us to include weather conditions or the presence of special events (football games or concerts) as covariates.

• Environmental and Resource Economics Review
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• v.19 no.1
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• pp.129-157
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• 2010

This paper is intended to evaluate energy efficiency policy in demand side, to assess the residential sector's energy efficiency policy and to analyze the system of energy efficiency practices. We examined residential energy consumption over the period 1990~2006. The decomposition method in the analysis was a logarithmic mean Divisia index (LMDI) techniques to decompose changes in energy intensity. First of all, the energy use in residential sector was adjusted to correct weather-induced variations in energy consumption, because adjustments for normal weather patterns facilitated inter-temporal comparison of intensity. The analysis on the residential sector shows that the overall energy intensity of the residential sector declined at an average 1.0% per year, while the structure effect increased by 1.8% per year, and the activity effect increased by 0.7% per year. In other words, the decline of floor space, number of household, and appliance ownership per capita has an effect on increase in residential consumption. The improvement in energy efficiency had strong contribution on the decrease of energy consumption. We find that the general results of analysis on residential energy are similar to those of IEA. The energy efficiency policy in residential sector is assessed to obtain some results during 1990~2006. In residential sector, structural variables such population per household, diffusion of appliance and activity factor such as population contributed to the increase of energy consumption while energy intensity effect induced the decrease of energy consumption. These findings are consistent with international trend as well as our prior expectation.

• Journal of Bio-Environment Control
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• v.12 no.1
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• pp.45-53
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• 2003

The object of this study was to develop the control technology of daily integral photosynthetic photon flux (PPF) by the artificial lighting and shading screen in greenhouse. The shading time needed to get the target PPF by using two types of shading screens having shading ratio of 55% and 85% was analyzed. The results showed the shading ratio of screen to be installed in greenhouse should be different depending on the amount of target PPF to be controlled. The PPF control experiment by using the 55% shading screen in July and August showed that the maximum difference between measured and calculated value was about 5 mol$.$ $m^{-2}$ $.$ $d^{-1}$ in no shading condition. This difference is satisfactory result because the daily integral PPF is quite different depending on the weather condition. The simulation result about PPF distribution pattern shortened the time needed to find the proper arrangement of artificial lightings in greenhouse. But the further study was required to find the supplemental lighting arrangement to be able to provide the exactly uniform distribution of target light intensity. The supplemental irradiation time needed to acquire the target daily integral PPF for different supplemental light intensities, weather conditions, and months was analyzed. The result showed that the supplemental light intensity should be decided depending on the amount of target PPF to be controlled. The result of PPF control experiment conducted by using 55% shading screen and 300 $\mu$mol$.$ $m^{-2}$ $.$ $s^{-1}$ supplemental light intensity from the end of May to the beginning of June showed that the maximum difference between target and measured value was about 3 mol$.$ $d^{-1}$ $.$ $m^{-2}$ . If we consider that the difference of the daily integral PPF depending on weather condition was the maximum 30 mol$.$ $m^{-2}$ $.$ $d^{-l}$, the control effect was acceptable. Although the result of this study was the PPF control technology to grow lettuce, the data and control method obtained could be employed for other crop production.n.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.56-63
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• 1991

This paper aims to describe the relation between the weather condition, especially typhoon and a shipwreck in Korean waters. For this study, it was investigated the statistical characteristics of a shipwreck due to the weather, pressure patterns governing the shipwreck in Korean waters. and the relation between the intensity of typhoon and the amount of a disaster. The results are summarized as follows: 1) The monthly occurrence frequency of a shipwreck was the heighest in July followed by February, March in descending order. 2) The pressure patterns governing the shipwreck were classified broadly into six types and pressure pattern which had most occurrence frequency of a shipwreck was Type V and then cames Type I, Type III and type IV in that order. 3) Occurence frequency of a shipwreck and the amount of a kinetic energy of typhoon have nothing to do with each other. In case of Wind-Typhoon that brought more a strong wind than a heavy rainfall, there were seriously affected ships and buildings by the wind.

• Atmosphere
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• v.20 no.1
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• pp.13-26
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• 2010

The Urban Canopy Model (UCM) implemented in WRF model is applied to improve urban meteorological forecast for fine-scale (about 1-km horizontal grid spacing) simulations over the city of Seoul. The results of the surface air temperature and wind speed predicted by WRF-UCM model is compared with those of the standard WRF model. The 2-m air temperature and wind speed of the standard WRF are found to be lower than observation, while the nocturnal urban canopy temperature from the WRF-UCM is superior to the surface air temperature from the standard WRF. Although urban canopy temperature (TC) is found to be lower at industrial sites, TC in high-intensity residential areas compares better with surface observation than 2-m temperature. 10-m wind speed is overestimated in urban area, while urban canopy wind (UC) is weaker than observation by the drag effect of the building. The coupled WRF-UCM represents the increase of urban heat from urban effects such as anthropogenic heat and buildings, etc. The study indicates that the WRF-UCM contributes for the improvement of urban weather forecast such nocturnal heat island, especially when an accurate urban information dataset is provided.

• KCID journal
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• v.21 no.1
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• pp.32-44
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• 2014

In Korea, global warming caused by the climate changes impacted on weather system with increase in frequency and intensity of precipitation, and the rainfall pattern changes significantly by regional groups. Furthermore, it is expected that the regional and annual fluctuation ranges of the rainfall in the future would be more severe. Nowadays, agricultural drainage system designed by the existing standard of 20-year return period and 2 days of fixation time cannot deal with the increment rainfall such as localized heavy rain and local torrential rainfalls. Therefore, it is required to reinforce the standard of the drainage system in order to reduce the agricultural flood damage brought by unusual weather. In addition, it is needed to improve the standard of agricultural drainage design in order to cultivate farm products in paddy fields as facility vegetable cultivation and up-land field crop have been damaged by the moisture injury and flooding. In order to prepare for the changes of rainfall pattern due to climate changes and improve the agricultural drainage design standards by the increase of cultivating farm products, the purpose of this study is to examine the impact of climate changes, the changes of relative design standard, and the analytic situation of agricultural flood damages, to consider the drainage design standard revision, and finally to prepare for enhanced agricultural drainage design standards.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.2
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• pp.119-130
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• 2012

Heat island phenomena in Chuncheon (Korea) were investigated using air temperature measured by automatic weather stations and temperature dataloggers located at rural and urban sites. Numerical simulation of the phenomena was performed using Weather Research and Forecasting Urban Canopy Model (WRF-UCM) and results were compared with the observation. The model was initialized with NCEP/FNL data. The horizontal resolution of the fine domain is 0.33 km. The results of observational analyses show that the intensity of heat island was significantly higher during the nighttime than during the daytime. The highest measured temperature difference between rural and urban site is $3.49^{\circ}C$ and average temperature difference varies between 1.4 and $1.9^{\circ}C$. Good agreement was found between the simulated and observed temperatures. However, significantly overestimated wind speed was found at the urban sites. The linear regression analysis between observed and simulated temperature shows high correlation coefficient 0.96 for urban and 0.94 for rural sites while for wind speed, a very low correlation coefficient was found, 0.30 and 0.55 respectively.

• Atmosphere
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• v.16 no.4
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• pp.319-332
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• 2006

This study examines the capability of the WRF (Weather Research and Forecasting) model in reproducing heavy rainfall that developed over the Korean peninsula on 26-27 June 2005. The model is configured with a triple nesting with the highest horizontal resolution at a 3-km grid, centered at Yang-dong, Gyeonggi-province, which recorded the rainfall amount of 376 mm. In addition to the control experiment employing realistic orography over Korea, two consequent sensitivity experiments with 1) no orography, and 2) no land over Korea were designed to investigate orographic effects on the development of heavy rainfall. The model was integrated for 48 hr, starting at 1200 UTC 25 June 2005. The overall features of the large-scale patterns including a cyclone associated with the heavy rainfall are reasonably reproduced by the control run. The spatial distribution of the simulated rainfall over Korea agreed fairly well with the observed. The amount of predicted maximum rainfall at the 3-km grid is 377 mm, which located about 50 km southeast from the observed point, Yang-Dong, indicating that the WRF model is capable of predicting heavy rainfall over Korea at the cloud resolving resolutions. Further, it was found that the complex orography over the Korean peninsula plays a role in enhancing the rainfall intensity by about 10%. The land-sea contrast over the peninsula was fund to be responsible for additional 10% increase of rainfall amount.

• Journal of Astronomy and Space Sciences
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• v.35 no.3
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• pp.151-161
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• 2018

Understanding solar influences on extreme weather is important. Insight into the causes of extreme weather events, including the solar-terrestrial connection, would allow better preparation for these events and help minimize the damage caused by disasters that threaten the human population. In this study, we examined category three, four, and five tropical cyclones that occurred in the western North Pacific Ocean from 1977 to 2016. We compared long-term trends in the positions of tropical cyclone occurrence and development with variations of the observed sunspot area, the solar North-South asymmetry, and the southern oscillation index (SOI). We found that tropical cyclones formed, had their maximum intensity, and terminated more northward in latitude and more westward in longitude over the period analyzed; they also became stronger during that period. It was found that tropical cyclones cannot be correlated or anti-correlated with the solar cycle. No evidence showing that properties (including positions of occurrence/development and other characteristics) of tropical cyclones are modulated by solar activity was found, at least not in terms of a spectral analysis using the wavelet transform method.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.3
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• pp.1-9
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• 1999

This paper described the results of the characteristics of the near-bottom flow and field analysis of the tidal flats sediment. It was the aim of this paper to grasp current flow of tidal flat's environment and influence factor for environmental change forecast of tidal flats. Field measurement of water velocity, water elevation, bed materials test, and temperature distribution of tidal flat were conducted. Thereafter, current flow, turbidity and temperature distribution of tidal flat sediment have been discussed. The field research results showed that the fluctuating velocity near the seabed before and after its appearance at low tide was strongly affected by the wind wave. The resuspension of the sea-bottom sediment took place with great intensity before and after the appearance of the seabed at low tide. Both the sea water level and the weather condition were a significant influential factors. Such as, temperature and turbidity just on the surface and the shallow layer of seabed sediments were varied largely with time and weather conditions, but that its deeper layers was almost constant. Temperature on the seabed sediments was strongly influenced by irradiance and water depth. The temperature variation of the tidal flat and the variation characteristics of the current flow and turbidity depend greatly on the inhabiting environment of the tidal flat benthic organism.