• Journal of Environmental Science International
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• v.26 no.2
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• pp.221-230
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• 2017

To determine the effect of air pollution reduction policies, the long-term trend of air pollutants should be analyzed. Kolmogorov-Zurbenko (KZ) filter is a low-pass filter, produced through repeated iterations of a moving average to separate each variable into its temporal components. The moving average for a KZ(m, p) filter is calculated by a filter with window length m and p iterations. The output of the first pass subsequently becomes the input for the next pass. Adjusting the window length and the number of iterations makes it possible to control the filtering of different scales of motion. To break down the daily mean $PM_{10}$ into individual time components, we assume that the original time series comprises of a long-term trend, seasonal variation, and a short-term component. The short-term component is attributable to weather and short-term fluctuations in precursor emissions, while the seasonal component is a result of changes in the solar angle. The long-term trend results from changes in overall emissions, pollutant transport, climate, policy and/or economics. The long-term trend of the daily mean $PM_{10}$ decreased sharply from $59.6ug/m^3$ in 2002 to $44.6ug/m^3$ in 2015. This suggests that there was a long-term downward trend since 2005. The difference between the unadjusted and meteorologically adjusted long-term $PM_{10}$ is small. Therefore, we can conclude that $PM_{10}$ is unaffected by the meteorological variables (total insolation, daily mean temperature, daily mean relative humidity, daily mean wind speed, and daily mean local atmospheric pressure) in Busan.

• KIEAE Journal
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• v.11 no.6
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• pp.53-62
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• 2011

This study aimed at suggesting improvement of lighting environment of the coffee house using study place. To this end, a series of field investigation was conducted in four possible target coffee houses around university. The field measurement included measurement of general illuminance and tabletop illuminance, observing illumination condition, and status of artificial lighting. Also, on-site questionnaire survey was administrated to 80 users of field measurement targets about using characteristics of coffee house and user's subjective response on light environment. The results are summarized as follows: (1) According to questionnaire survey, most of users checked 'learning (study and reading)' in 'purpose of coffee house using', and 'slightly dark' was checked most in each subjective response (brightness on general space and on tabletop at daytime/night); (2) as results of measurements on general illuminance and on tabletop illuminance during daytime, only one coffee house was suitable for standard; (3) as results of measurements on illuminance during night, all target coffee houses were not met the standard; (4) as results of uniformity ratios, almost uniformities of general illuminance were not met the standard except one case. The common problems of lighting environment of coffee house were analyzed as lack of daylight illumination e.g. having low amount of sunshine from skylight, un-uniformity of insolation by floor plan and absence of window blind, and un-uniformity of artificial luminous intensity e.g. lack of the number or brightness of artificial lighting, using the indirect lighting, using only local lighting, and non-uniform arrangement of artificial lighting.

• Journal of Energy Engineering
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• v.29 no.1
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• pp.44-51
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• 2020

The importance of ESS has been emphasized due to stabilization of power demand due to deterioration of network reliability and expansion of renewable energy sources. ESS (Energy Storage System) stores the remaining power and uses it when necessary to meet the power demand, and build the ESS system mainly in conjunction with solar and wind power. In this paper, we propose a home PV Charging Module using the Master-Slave method which is effective for low insolation. After designing the module, Fast MPPT algorithm is applied to generate the maximum output from the nonlinear output characteristics of the PV modules. The average power value for the input of PV Charging Module was 296.90 W and the output power was 289.60 W, which averaged 97.54%.

• Atmosphere
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• v.26 no.1
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• pp.159-183
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• 2016

On 31 July 2014, there was a localized torrential rainfall ($58.5mm\;hr^{-1}$) caused by a strong convective cell with thunder showers over Daegwallyeong. In the surface synoptic chart, a typhoon was positioned in the East China Sea and the subtropical high was expanded to the Korean peninsula. A WRF (Weather Research and Forecasting) numerical simulation with a resolution of 1 km was performed for a detailed analysis. The simulation result showed a similar pattern in a reflectivity distribution particularly over the Gangwon-do region, compared with the radar reflectivity. According to the results of the WRF simulation, the process and mechanism of the localized heavy rainfall over Daegwallyeong are as follows: (1) a convective instability over the middle part of the Korean peninsula was enhanced due to the low level advection of warm and humid air from the North Pacific high. (2) There was easterly flow from the coast to the mountainous regions around Daegwallyeong, which was generated by the differential heating of the insolation among Daegwallyeong and the Yeongdong coastal plain, and nearby coastal waters. (3) In addition, westerly flow from the western part of Daegwallyeong caused a strong convergence in this region, generating a strong upward motion combined by an orographic effect. (4) This brought about a new convective cell over Daegwallyeong. And this cell was more developed by the outflow from another thunderstorm cell to the south, and finally these two cells were merged to develop as a strong convective cell with thunder showers, leading to the record breaking maximum rainfall per hour ($58.5mm\;hr^{-1}$) in July.

• Solar Energy
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• v.11 no.1
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• pp.27-40
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• 1991

Research and development works on practical application of natural energy utilization systems involving solar, wind and sea wave energies are under promoting for the purpose of improving the energy consumption structure. These natural energies, made available with the use of relatively simple apparatus, are clean economically efficient and highly effective in the conservation of environment. However, these natural energies also have low energy density, randomness and regional variations. To compensate for these characteristics, hybrid utilization of solar and wind energies is currently under study. The introduction of a plural number of the natural energy hybrid utilization systems into a specific area will affect the economic efficiency, reliability and environmental conservation. Evaluation method of such effects has been examined in this study. The present method consisted of the steps described below. First, available energy was calculated from insolation distribution and wind velocity distribution in the specified area, and then the effect on the configuration of the power system load was obtained. This was followed by the determination of the optimal power dispatch over the specified period and by evaluations in light of economic efficiency, reliability and environmental indices.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.11
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• pp.581-586
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• 2015

In this study, an analysis was performed on the performance of the solar water heating system with geo-thermal heat pump for a detached house. This system has a flat plate solar collector ($8\;m^2$) and a 3 RT heat pump. The heat pump acts as an auxiliary heater of the solar water heating system. These systems were installed at four individual houses with the same area of $100\;m^2$. The monitoring results for one year are as follows. (1) The average daily operating time of the solar system appeared to be 313 minutes in spring (intermediate season), and 135 minutes and 76 minutes in winter and summer respectively. The reason for the short operating time in summer is the high storage temperature due to low water heating load. The high storage temperature is caused by a decrease in collecting efficiency as well as by overheating. (2) The geothermal heat pump as an auxiliary heater mainly operates on days of poor insolation during the winter season. (3) Despite controlling for total house area, hot water consumption varies greatly according to the number of people in the family, hot water usage habits, etc. (4) The yearly solar fraction was 69.8 to 91.5 percent, which exceeds the maximum value of 80% as recommended by ASHRAE. So the solar collector area of $8\;m^2$ appeared to be somewhat greater for the house with an area of $100\;m^2$. (5) The observed annual efficiency of solar systems was relatively low at 13.5 to 23.6%, which was analyzed to be due to the decrease in thermal efficiency and the overheating caused by a high solar fraction.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.225-234
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• 2006

Using the data from the sea water monitoring system installed at the Ieodo Ocean Research Station, we have analyzed the water properties around the station as well as the characteristics of the fresh water from the Changjiang River and the influence of typhoons on the sea water. In general, the accuracy and stability of the temperature data are high, but those of the salinity data are worse than the specification of the instruments. The daily variation of temperature and salinity is mainly controlled by the vertical motion of a water column due to semi-diurnal tide and diurnal change in the solar insolation. Seasonal change is prominent in temperature data. The freshwater from the Changjiang River is the main cause of large salinity variation. In August 2003 and August 2004, about 10 days before fresh water was observed near the Jeju Island, low salinity water was observed at the Ieodo Station. On the other hand, in July 2005 fresh water was observed at the station but not at around the Jeju Island. In other words, the fresh water observed at the Ieodo Station does not always expand to the Jeju Island. Two strong typhoons passed by the station in September 2003 and August 2004. The effects of the typhoons were lasted for 3 to 4 days.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.56-69
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• 2021

In this paper, the PV system with a link to the commercial system needs some advantages like small capacity, high power factor, high reliability, low harmonic output, maximum power operation of solar cell, and low cost, etc. as well as the properties of inverter. To transfer the PV energy of photovoltaic power generation system to the system and load, it requires PCS in both directions. The purpose of this paper is to confirm the stable power supply through the load leveling by presenting the PCS considering ESS of photovoltaic power generation. In order to achieve these purpose, 5 step process of operation mode algorithm were used according to the solar insolation amount and load capacity and the controller for charging/ discharging control was designed. For bidirectional and effective energy transfer, the bidirectional converter and battery at DC-link stage were connected and the DC-link voltage and inverter output voltage through the interactive inverter were controlled. In order to prove the validity of the suggested system, the simulation using PSIM was performed and were reviewed for its validity and stability. The 3[kW] PCS was manufactured and its test was conducted in order to check this situation. In addition, the system characteristics suggested through the test results was verified and the PCS system presented in this study was excellent and stronger than that of before system.

• Korean Journal of Plant Resources
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• v.37 no.1
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• pp.62-70
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• 2024

Fruit thinning rate and characteristics were investigated for three years on seven promising pear (Pyrus pyrifolia Nakai) cultivars, which were treated by lime-sulfur as an eco-chemical thinning substance. Lime-sulfur was treated twice at the second and third days after full bloom by cultivar. Most of pear cultivars were significantly thinned by lime-sulfur compounds. Especially 'Whangkeumbae', 'Supergold' and 'Hanareum' exhibited high flower thinning rates, 41.5%, 40.1% and 39.9%, respectively. As weather conditions at the lime-sulfur treatment, insolation and cloud amount were correlated with flower thinning rate but not significant (r = 0.49 and r = -0.45, respectively). These results suggest that lime-sulfur is suitable for reducing labor force for flower thinning of Korean pears but flower thinning effects of lime-sulfur can vary depending on other factors such as environmental conditions. This information will provide useful data for low labor force cultivation of Korean pear cultivars.

• Journal of the Korean Institute of Rural Architecture
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• v.16 no.1
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• pp.35-42
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• 2014

Due to the development of civilization, the humans is privileged the rich of technologies for housing thermal environment. But, this kind of technological development caused enough trouble of energy excessive consumption. For solve this problem, many researchers strive to exploit the low energy sustainable techniques. For such a reason, the eco-friendly techniques of vernacular house are resurfacing. These traditional techniques are applied to a development of eco-friendly modern housing. They are no longer recognized as outdated products. On this context, this study proposes an scientific analysis on the thermal environment characteristics of Neolithic thatched-roof dugout hut(Um house). So far the several studies have been carried out in viewpoint of the history and structural compositions of the Um house which has been used as the normal housing for about 1000 years in the Neolithic era, however the thermal characteristics analysis of the Um house has never been studied. Um house is not a housing which has been composed by the scientific analysis or architectural design technology, but evolved empirically over a long period. This study on the thermal environment characteristics of Um house would provide basic information for the development of korean eco-friendly rural housing by korean climate characteristics. In this study, the thermal environmental characteristics of the Um house in the Neolithic era was analysed experimentally. The results of this study could be summarized as follows: 1. When the solar insolation and the ambient temperature in the daytime were $420W/m^2$ and $17^{\circ}C$ respectively, the surface temperature of the Um house roof covered with the rice straw was $37^{\circ}C$ and that in the roof $32^{\circ}C$, and in the conditions above the air temperature in the room was $15^{\circ}C$. 2. When the ambient relative humidity was 40%, that in the room of the Um house 50%, and at the ambient relative humidity of 90~100%, that in the room was 60%. 3. Through the experimental analysis, it was verified that the enthalpy and relative humidity is in an inverse relationship. 4. In general the comfort degree in the living space is changed with the seasonal climate, also in this study, the comfort degree in the room of the Um house in October and November was higher than that in May and June.