Kyung-Hun Park’s research while affiliated with Changwon National University and other places

A photocatalyst that can adsorb particulate matter (PM) with an electric charge is a popular method for PM reduction. Some commonly used photocatalysts comprise single metal oxides such as TiO2 and ZnO, which could be utilized under ultraviolet (UV) region. However, because UV region constitutes a very small part of the total wavelength of sunlight, technology needs to be developed that allows the utilization of the visible region as well. Herein, we developed a new organic material that activated under not only UV region but also visible region by utilizing methylene blue (MB) with TiO2. To make the TiO2–MB film adsorb well, we discuss various solvents, concentration controls, and even coating methods. By conducting NO removal test, we showed that it is possible to reduce the PM more effectively by using TiO2–MB film than that achieved using TiO2 alone.

Long-term monitoring was performed between December 2017 and November 2018 on cool roof–applied building (CR) and non-cool roof–applied building (NCR). The study was conducted in Changown city South Korea, which has a humid subtropical climate, to identify the temperature reduction effect on different building layers (rooftop surface, ceiling surface and air, and room air). With respect to the temperature reduction effect by layer according to the application of a cool roof (NCR−CR), the rooftop surface temperature showed an increasing temperature reduction effect with increase in air temperature. Ceiling surface and air temperatures showed similar temperature reduction effects in summer and winter, whereas room air temperature showed greater temperature reduction in the winter than in summer. This finding was contrary to the results for room air temperature in the winter reported in previous studies. In conclusion, the present study confirmed that applying cool roofs on buildings located in humid subtropical climates has more pronounced effects in terms of reduced indoor temperature (ceiling surface, ceiling air, and room air) in winter than in summer. The long-term measurement results produced in this study may be used as basic data for establishing criteria for cool roof performance and product selection in South Korea.

The purpose of this study was to analyze the surface temperature of surface fabrics using UAV TIR images, to mitigate problems in the thermal environment of urban areas. Surface temperature values derived from UAV images were compared with those measured in-situ during the similar period as when the images were taken. The difference in the in-situ measured and UAV image derived surface temperatures is the highest for gray colored concrete roof fabrics, at 17℃, and urethane fabrics show the lowest difference, at 0.3℃. The experiment power of the scatter plot of in-situ measured and UAV image derived surface temperatures was 63.75%, indicating that the correlation between the two is high. The surface fabrics with high temperature are metal roofs(48.9℃), urethane(43.4℃), and gray colored concrete roofs(42.9℃), and those with low temperature are barren land(30.2℃), area with trees and lawns(30.2℃), and white colored concrete roofs(34.9℃). These results show that accurate analysis of the thermal characteristics of surface fabrics is possible using UAV images. In future, it will be necessary to increase the usability of UAV images via comparison with in-situ data and linkage to satellite imagery.

Purpose: Recently, cities have suffered thermal problems such as increases in energy consumption and the number of heat-wave-induced patients and tropical nights. To mitigate these kinds of problems, the use of cool roofs with high reflective coating as an effective intercept of solar radiation from the roof in order to reduce building temperature was investigated in this work. Actual buildings in a southern area of Korea were used in this case study. Method: The experimental buildings had similar locations, sizes, and aspects and were divided into those with cool roof application (CR) and no cool roof application (NCR). Temperature of the roof surface, ceiling surface, ceiling air, and room air layers using contact-type thermometers and thermo-hygrometers; thermal emittance; and solar reflectance were measured. Result: First, the thermal emittance, on average, was 0.85 with NCR and 0.95 with CR. Solar reflectance was 0.15 with NCR and 0.15 before and 0.75 after CR. Second, roof surface temperature with CR was 8.4 ℃ (August) and 6.6 ℃ (September) cooler than with NCR. Third, on a weekend in September, maximum ceiling and room air temperatures were 3.7 ℃ and 1.7 ℃ cooler, respectively, with CR than with NCR. Weekend data were compared because air conditioning was not used at that time.

The purpose of this study was to offer the basic data for conservation of wetland ecosystem by surveying and analysing the vascular plants distributed in Hwapocheon wetland, Gimhae, Gyeongnam, Korea. The numbers of vascular plants were summarized as 292 taxa including 72 families, 192 genera, 262 species, 1 subspecies, 26 varieties and 3 forms. There were 34 taxa of hydrophytes, 23 taxa of emergent plants, 4 taxa of floating-leaved plants, 5 taxa of free-floating plants and 5 taxa of submerged plants. The rare plants were 7 taxa including Aristolochia contorta, Penthorum chinense, Prunus yedoensis(planting), Ixeris tamagawaensis, Hydrocharis dubia, Iris ensata var. spontanea(planting), Acorus calamus and so forth. The Korean endemic plants were 2 taxa including Salix koriyanagi and Salix pseudolasiogyne. The specific plants by floristic region were 19 taxa including 2 taxa of grade V, 1 taxa of grade IV, 5 taxa of grade III, 2 taxa of grade II and 9 taxa of grade I. The naturalized plants were 62 taxa including Chenopodium album, Astragalus sinicus, Helianthus tuberosus, Panicum dichotomiflorum and so forth. The plants that were expected to spread nationwide were 14 taxa including Cerastium glomeratum, Bidens frondosa, Tagetes minuta, Festuca arundinacea and so forth. The invasive alien plants were 6 taxa including Rumex acetosella, Sicyos angulatus, Ambrosia artemisiifolia, Ambrosia trifida, Aster pilosus and Lactuca scariola.

In this study, we compared the temperature in models with four different roof types: model A(green roof), B(white colored roof) , C(green colored roof), and D(black colored roof) using the simulation. During both summer and winter, the roof surface outside temperature was found to be the lowest on the model B in the daytime and the nighttime, whereas the model A had the highest temperature in the nighttime. The zone mean air temperature was the lowest on the model A and highest on model D in the summer daytime. During winter, the model B was found to have the lowest temperature. The model A and D had the highest temperature in the nighttime and daytime, respectively. This indicates that the use of model B as cool roofs in Korea could reduce building temperatures in the summer.

Purpose: PMV, PET, and similar thermal comfort indices and microclimate modeling have recently become actively used to evaluate thermal comfort. This study will look at pedestrian roads with diverse spatial characteristics on university campus using the ENVI-met model as the base for onsite measurement. Method: The PET was used as the thermal comfort index. The first microclimate measures were collected on September 20, 2014, and the second microclimate measures were collected on June 1, 2015. The ENVI-met model was used at the same time. Result: As a results, Onsite measurement results differed depending on the PET spatial characteristics. The location associated with the most discomfort had a PET of 47.8^{\circ}C. The spatial characteristics of this place included a with no shade. The most comfortable location had shade, and the PET was 24.6^{\circ}C. When the ENVI-met model and onsite measurements were compared, similar patterns were found, but with a few differences at specific points; this was due to the limitation of using input materials such as trees, buildings, and covering materials with the ENVI-met model. This factor must be thoroughly considered when analyzing modeling results.

Purpose: This study aims to identify the effect of temperature reduction by the application of cool roof coatings to Changwon City Hall in South Gyeongsang Province. The indoor and outdoor temperatures of the cool roofing building were analyzed and compared to that of an existing building with green-colored roof coated with waterproof polyurethane. Method: The surface temperatures and reflectivity of rooftops, surface temperatures of ceilings and the interior, and outdoor temperature and humidity of the two aforementioned buildings were measured from June to September in 2014. The measurements were taken every 10 min. Result: The surface temperature of the building with the cool roof was lower by a maximum of 9 °C with the reflectivity of the rooftop at an average of 0.55, which is higher than that of the building with green polyurethane by approximately 0.3. The temperature of the ceiling inside the building with the cool roof was about 1~2 °C lower than that of the ordinary building. Also, the indoor temperature of the office with cool roof coatings was about 0.5~1.0 °C lower than that of the office with green-colored roofing building. The results show that cool roof coatings can lower the temperature of buildings. In the next research, the reduction in consumption of energy for air conditioning will be investigated by utilizing building energy simulation tools.