• Journal of Digital Convergence
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• v.18 no.4
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• pp.55-65
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• 2020

The factors for service quality improvement of frozen and refrigerated warehouses are derived and the differences in perception about service quality improvement between shippers and operators of frozen and refrigerated cargos are analyzed. The objective of this study is to propose quality improvement measures for frozen and refrigerated cargo services using the importance-performance analysis (IPA). As a result, 15 analysis factors were derived. It was found through independent sample t-test that there is no difference in perception about quality improvement between shippers and operators. Furthermore, four top priority investment areas were derived from the IPA: maintaining temperature and humidity, securing variable storage space, on-time stocking and releasing, and providing information service. Meanwhile, inventory management service ability, on-time stocking and releasing, and reliable cargo storage ability needed urgent improvement. This study has industrial implications in that it proposes practical improvement measures for service quality improvement.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.11
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• pp.527-536
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• 2017

With the recent development of smart grid industry, the necessity for efficient EMS(Energy Management System) has been increased. In particular, in order to reduce electric load and energy cost, sophisticated electric load forecasting and efficient smart grid operation strategy are required. In this paper, for more accurate electric load forecasting, we extend the data collected at demand time into high time resolution and construct an artificial neural network-based forecasting model appropriate for the high time resolution data. Furthermore, to improve the accuracy of electric load forecasting, time series data of sequence form are transformed into continuous data of two-dimensional space to solve that problem that machine learning methods cannot reflect the periodicity of time series data. In addition, to consider external factors such as temperature and humidity in accordance with the time resolution, we estimate their value at the time resolution using linear interpolation method. Finally, we apply the PCA(Principal Component Analysis) algorithm to the feature vector composed of external factors to remove data which have little correlation with the power data. Finally, we perform the evaluation of our model through 5-fold cross-validation. The results show that forecasting based on higher time resolution improve the accuracy and the best error rate of 3.71% was achieved at the 3-min resolution.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1996.05a
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• pp.91-115
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• 1996

In the recent years, protected horticultural facilities have been modernized and glasshouses are also propagating in Korea, even most vegetables production are conducted in the traditional plastic houses covered with, for example, PVC film for just temperature keeping. It would limit the productivity and competitivity of the vegetable production industry without automatization and high quality year round production. A plant factory, aimed to produce vegetables in the limited areas, was initiated in Christensen farm, Denmark in 1957, and widely propagated in some developed countries. As it has the automatized system which enables to keep optimized environment conditions, it will be the best facility for high quality products as well as year round planned production. However, we have not even started the plant factory production. Since the plant factory is requiring lots of resources, besides plant cultivation technologies, such as environment control, automatic engineering and robotics, our approach to the development of plant factories should be minded on Practical Plant Factories considering our current farming practices and least capital needs rather than blindly employing the advanced technologies from developed countries. Thus, Korean plant factory development can be initiated with year round leaf vegetables production in NFT or DFT cultivation system instead of the moval bed system, in which aerial environment factors such as light, temperature, humidity and CO$_2$ concentration and root environment ones such as solution concentration, temperature, pH and water soluble oxygen shall be automatically controlled. And the seeding, seedling and transplanting operations shall be accomplished in the house entrance, and the harvesting and grading opreations shall be conducted in the house exit. For practical plant factories, environment control technologies including artificial light source, illumination and air conditioning, automatic management for nutrient solution and automatic production line of moval bed system, transplanting and harvest should be developed along with researches on the cost reduction of factory building construction.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.2
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• pp.77-84
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• 1992

This experiment was designed to gain information on factors affecting stubble death of orchardgrass (Dactylis glomerata L.) during the first rainy season. According to the experimental plan, the effects of sowing methods, drainages and cutting dates on the stubble carbohydrate content of orchardgrass, available soil moisture content of experimental plots, temperatures at the ground level and in the soil, and relative light intensity and humidity at the base of orchardgrass canopy were measured during the rainy season. The carbohydrate content of orchardgrass was sharply decreased to 2.9 % at 3rd day after cutting in the plots cut before rainy season and a gradural recovery was noted following the sharp reduction, but in the plots cut after rainy season, orchardgrass showed 5.5% of carbohydrate content before cutting and 3.0% at the 3rd day after cutting. The same pattern in both carbohydrate reduction and recovery was found between two cutting treatments. The available soil moisture content in the plots cut before rainy season was slightly higher than that in the plots cut after rainy season. But after the rainy season, the available soil moisture content in the plots cut after rainy season was higher than that in the plots cut before rainy season. Soil temperature at lOcm depths in the plots cut before rainy season was higher than that in the plots cut after rainy season. Daily maximum air temperature at the ground level in the plots cut before rainy season was higher than that in the plots cut after rainy season and changeable. Relative humidity at the ground level was below 70% in the plots cut before rainy season, but 75 to 90 % was observed in the plots cut after rainy season. Relative light intensity at the ground level in the plots cut before rainy season was much higher, recorded 50 to 90 %, than that in the plots cut after rainy season showing less than 10%. The results of this study suggest that the stubble death of orchardgrass during the rainy season is due to plant diseases influenced by a decrease of light penetration and increase of relative humidity at the base of the grass canopy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.27-33
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• 2016

Military textiles with breathable waterproof materials are expanding as form of winter clothes. Waterproof moisture-permeable clothes are very important for soldiers to survive in cold weather operations because they prevent loss of body heat from the penetration of water into the human body. Korea military uses the water resistance and moisture permeability to test the performance of waterproof moisture-permeable materials. Moisture permeability is measured according to the amount of evaporated water vapor passing through a fabric under specified temperature and humidity by using acetic acid potassium presented in KS K 0594. However, the test procedure for measuring the moisture permeability in the standard is presented only briefly and the preparation procedures for the test in accredited testing institutions are applied differently, leading to significant deviation of the results. This paper compares the procedures of testing institutions and examines the factors that affect moisture permeability. Finally, we propose a procedure to reduce the deviation of results and apply the proposed procedure in testing institutions. Our analysis results with one-way ANOVA under significant level (0.05) confirm that the deviation of results is reduced.

• Journal of Korea Water Resources Association
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• v.54 no.8
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• pp.577-587
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• 2021

Drought is generally considered to be a natural disaster caused by accumulated water shortages over a long period of time, taking months or years and slowly occurring. However, climate change has led to rapid changes in weather and environmental factors that directly affect agriculture, and extreme weather conditions have led to an increase in the frequency of rapidly developing droughts within weeks to months. This phenomenon is defined as 'Flash Drought', which is caused by an increase in surface temperature over a relatively short period of time and abnormally low and rapidly decreasing soil moisture. The detection and analysis of flash drought is essential because it has a significant impact on agriculture and natural ecosystems, and its impacts are associated with agricultural drought impacts. In South Korea, there is no clear definition of flash drought, so the purpose of this study is to identify and analyze its characteristics. In this study, flash drought detection condition was presented based on the satellite-derived drought index Evaporative Stress Index (ESI) from 2014 to 2018. ESI is used as an early warning indicator for rapidly-occurring flash drought a short period of time due to its similar relationship with reduced soil moisture content, lack of precipitation, increased evaporative demand due to low humidity, high temperature, and strong winds. The flash droughts were analyzed using hydrometeorological characteristics by comparing Standardized Precipitation Index (SPI), soil moisture, maximum temperature, relative humidity, wind speed, and precipitation. The correlation was analyzed based on the 8 weeks prior to the occurrence of the flash drought, and in most cases, a high correlation of 0.8(-0.8) or higher(lower) was expressed for ESI and SPI, soil moisture, and maximum temperature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4335-4347
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• 2015

The objective of this study was to investigate $PM_{10}$ and $CO_2$ concentrations in the classrooms of 286 elementary schools in Suwon, Ansan, and Hwaseong in the province of Gyeonggi between August 2008 and December 2012. By gaining an understanding of the environmental factors that influence these concentrations, this study also aimed to establish a management plan for indoor air quality in schools, which substantially affects the health of elementary students. When the schools were classified by region, no statistically significant difference in $PM_{10}$ concentration was observed. However, $PM_{10}$ concentration was relatively high in industrial areas and low in rural areas. No difference in $CO_2$ concentration was observed among the surveyed cities. Analysis of annual $PM_{10}$ concentration showed that the highest values for Suwon and Hwaseong occurred in 2008 and 2009, respectively (p<0.01). In the case of Ansan, the highest concentration occurred during 2009, but the difference was not significant compared to the other years. Analysis of the annual $CO_2$ concentration of each city shows no significant difference among the cities (p-value=0.366,0.730,0.210). According to a time series analysis of $PM_{10}$ and $CO_2$ by season, from autumn 2008 to winter 2012, $PM_{10}$ concentration was high during 2009, then it gradually decreased until 2012, and started to increase again. While no difference in annual $CO_2$ concentration was observed, the concentration had a tendency to be higher in spring and winter than in summer. By analyzing the relationship between $PM_{10}$ and $CO_2$ and the environmental factors (years of construction, average students of classroom, temperature, and humidity), it showed a significant negative correlation was found between $CO_2$ and the environmental temperature and humidity, at -0.329 and -0.188, respectively (p<0.01).

• Journal of Digital Convergence
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• v.15 no.11
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• pp.121-131
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• 2017

The Fuzzy-analytic hierarchy process (AHP) was adopted as the methodology for this study because it allows for the use qualitative judgments by experts. Based on results of the analysis of the success factors for frozen storage/cold storage warehouses, the facility factor was identified as the most important to consider. This factor had a weight of 0.307, followed by systems and operations, accessibility, and standardization/automation with weights of 0.263, 0.255, and 0.175, respectively. The conclusions and implications of the study are as follows. First, the efficiency of constant temperature and humidity systems and the heat insulation property of buildings need to be enhanced. Second, the efficiency of the operations should be enhanced through the standardization of equipment rather than by standardizing product loading. Finally, since logistics and transportation costs are higher for frozen storage/cold storage warehouses than for general distribution, accessibility needs to be considered as the first priority.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.675-695
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• 2023

The tracksite of dinosaurs and pterosaurs in Sanbuk-dong of Gunsan is the largest early Cretaceous dinosaur footprint fossil site in Korea, and all the footprints are important evidence indicating that large ornithopod and theropod dinosaurs inhabited the Korean peninsula during the early Cretaceous. The Sanbuk-dong site was covered with waterproof sheet in an outdoor environment until the installation of a protective enclosure in 2021. As a result, various factors such as shear force, load reduction, temperature and humidity fluctuations, acid rain, salinity and microorganisms have complexly interacted in the substrate of fossils, exacerbating the damage to footprints. For 159 footprints in 12 trackways among the footprints found in the site, the damage types were classified in detail and the level of each damage was assessed. The damages were classified into 6 types through the classification of deterioration degree of individual footprints. As a result of ultrasonic physical property evaluation on the surface of the fossil site, most of these footprints are in the completely weathered (CW) stage. Furthermore, various weathering patterns were observed in the study area, and surface contaminants were analyzed along the stratigraphy. Although the patterns of freshness and contaminants varied at different points within the fossil site, the chemical compositions were similar. Based on the results, an efficient conservation management system for dinosaur footprint fossils was established, and a conservation treatment type for each footprint was proposed.

• Journal of Korea Water Resources Association
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• v.56 no.10
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• pp.619-629
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• 2023

Recent intensification of climate change has led to an increase in damages caused by droughts. Currently, in Korea, the Standardized Precipitation Index (SPI) is used as a criterion to classify the intensity of droughts. Based on the accumulated precipitation over the past six months (SPI-6), meteorological drought intensities are classified into four categories: concern, caution, alert, and severe. However, there is a limitation in classifying drought intensity solely based on precipitation. To overcome the limitations of the meteorological drought warning criteria based on SPI, this study collected emergency water supply damage data from the National Drought Information Portal (NDIP) to classify drought intensity. Factors of SPI, such as precipitation, and factors used to calculate evapotranspiration, such as temperature and humidity, were indexed using min-max normalization. Coefficients for each factor were determined based on the Genetic Algorithm (GA). The drought intensity based on emergency water supply was used as the dependent variable, and the coefficients of each meteorological factor determined by GA were used as coefficients to derive a new Drought Severity Classification Index (DSCI). After deriving the DSCI, cumulative distribution functions were used to present intensity stage classification boundaries. It is anticipated that using the proposed DSCI in this study will allow for more accurate drought intensity classification than the traditional SPI, supporting decision-making for disaster management personnel.