• Journal of Bio-Environment Control
• /
• v.30 no.3
• /
• pp.230-236
• /
• 2021

Changes in greenhouse temperature and solar radiation due to fogging and shading were monitored during hydroponics in high temperature in summer season. Experiment 1 consists of four treatments, namely, Control, Shading, Fogging, and Fogging + Shading based on sunny days August. For Experiment 2, two melon cultivars of 'Dalgona' and 'Sopoong gaza' were cultivated in summer of 2020 using Fogging + Shading with the best result for temperature reduction effect from Experiment 1. As a result of Experiment 1, the effect of Fogging + Shading on temperature reduction was apparent where the inside was about 4℃ (as the lowest temperature) lower than the outside. Fogging + Shading showed the inside was 2-4℃ lower than the outside, and Fogging or Shading treatments had little difference, compared to the Control where the internal temperature of greenhouse was 3-4℃ higher than the external. For solar radiation changes between greenhouse inside and outside, the internal change was in a similar pattern between Fogging and Control, and between Shading and Fogging + Shading, respectively. In case of the Fogging treatment (similar with the Control) only the effect of solar radiation reduction as influenced by plastic greenhouse covering materials was examined. The Fogging + Shading had a very similar change in solar radiation to the Shading. Based on these results, Experiment 2 was conducted in summer of 2020 and resulted in a temperature reduction effect of about 3.9℃ according as the inside of air-conditioned greenhouse was kept 32.4℃ when the maximum temperature of the outside reached 36.3℃ in August during the cultivation period. In addition, the quality of melon fruit was good (1.3-1.5 kg of fruit weight, 12.6-13.3 of soluble solids content. In the case of using Fogging + Shading cooling treatment, it can bring about the effect of reducing the temperature during the high temperature in summer, and normal growth of melon and fruit harvesting were possible.

• Journal of the Korean association of regional geographers
• /
• v.11 no.5
• /
• pp.383-390
• /
• 2005

The purpose of this study is to show distribution pattern of comfortable Indoor-Temperature in South Korea based on 10-days normal data(June 3rd, July 2nd, August 1st). Comfortable Indoor-Temperature values and Heat flow equation values for the 68 stations are constructed to show how man tend to feel in various areas. In the early summer, comfortable Indoor-Temperature is very low in Taegwallong regions and the Southern interior regions due to the influence of the orographic effects or the altitude. In the hot summer, All regions except Taegwallong and Central interior regions have been the high value. These are largely derived from the low Clo-values due to the stable weather with the highest insolation, humidity and strong radiation heat by the North Pacific Anticyclone appears in Eastern Asia.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.5
• /
• pp.1187-1195
• /
• 2013

Photovoltaic inverters should always track the maximum power of solar cell arrays in operation. Also, they should be irrespective of the maximum power point voltage of a wide range of solar cells in tracking the maximum power point. If the current ripple of solar cells occurs, the function of maximum power point tracking drops, and normal tracking is difficult when solar radiation or the maximum power point changes. To solve this problem, this paper proposed a new maximum power point tracking algorithm with high efficiency and an algorithm to reduce the current ripple of solar cells. According to the results from the test on 4KW grid-connected PV inverter, the efficiency of maximum power point tracking and inverter output and the total harmonic distortion of inverter output current showed 99.97%, 97.5% and 1.05% respectively. So, the inverter showed excellent performance, and made possible stable maximum power point tracking operation when the solar radiation rapidly changed from 100% to 10% and from 10% to 100% for 0.5 seconds.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.41 no.3
• /
• pp.22-30
• /
• 2013

This study aims to measure the thermal comfort effects of urban street trees. As the usual dry bulb air temperature does not indicate properly how the average pedestrian feels the heat of a typical summer day under the strong sunshine, we adopted the Wet Bulb Globe Temperature(WBGT). WBGT involves black globe temperature to measure the direct radiation of sun beams on our bodies, for example our heads. We measured temperatures on very sunny and hot summer days, August 3, 4, and 7, 2012, on the urban streets of Seoul, Korea. Wet bulb, globe, and dry bulb temperatures were measured under direct sunlight from 1 O'clock to 5 O'clock pm. Globe and dry bulb temperatures were measured under street tree shades nearby during the same hours. Then the WBGTs were calculated with the formulae, one for sunny outdoor spaces, and the other for shaded outdoor spaces or indoor. The results are compared with the Korean Standards Association(KS A ISO 7243). The major findings were: 1) On very sunny and hot summer days in Seoul, street tree shades lower the WBGT about 1 to 4 degrees, 2) during the hours of 3 and 4 O'clock in the afternoon, the WBGT under the tree shades are about 3 to 4 degrees lower compared to those under sunshines(approx. 29 to 32 degrees respectively), 3) This difference makes a major thermal comfort for urban pedestrians because senior citizens or weak persons are recommended to move indoor, and even healthy people are recommended stop outdoor sports and take rests in the shades when WBGT is about 32. On the other hand, if the WBGT is around 29, or 3 degrees lower, slower walking, light works or sports are allowable, 4) On site questionnaire survey confirms the thermal comforts under the tree shades, and we even could not get survey subjects on the sunny parts of the sidewalks, 5) We strongly recommend change of guidelines for urban street trees from "one row of street trees on 6m~8m intervals" to "street trees to make continuous shades".

• Journal of the Korean association of regional geographers
• /
• v.10 no.1
• /
• pp.151-157
• /
• 2004

In January the clo-values show two characteristic patterns on the insulation, Samjiyon has the highest clo-values while Changjon has the lowest in North Korea, and the coastal areas are lower than in the interior areas. This regional difference is a result of predominant temperature, wind speed and orographic effects. Particularly, in August the coastal areas are generally lower than the interior areas because of orographic effects(wind direction, wind speed). All regions except Samjiyon legions and northern interior regions have low values during the period from the early August to the middle of August. These are largely derived from the stable weather with the highest temperature, humidity and strong radiation by the North Pacific Anticyclone appears in Eastern Asia.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.25 no.1
• /
• pp.1-7
• /
• 1980

In 1976, a newly released rice variety, Yushin, was planted in 300,000 ha of the 533,000 ha of cultivated total hecterage with new rice varieties. High productivity and quality were achieved by farmers around country. However, the wilting phenomena of Yushin occured in some regions where were employed poor cultural management, and flowed sewage into the paddy field from industrial factories. This study was identified some factors for the wilting phenomena of Yushin rice variety in morphological and physiological aspects. The Yushin variety showed greater internode elongation on low part of the stems that close related to lodge at heavier nitrogen levels, excessive number of spikelets per unit leaf blade weight i.e. higher sink/source ratio, and greater consumption of respiratory substrate by increased respiration rate of rice plant as compared with those of Tongil rice variety. In physilogical aspects, the Yushin variety was significantly declined root development and root activities under heavy nitrogen conditions. Yushin rice variety was decreased $K_2$O/N ratio, carbohydrate content in stem of rice plant, and physiological root activities specially in low light intensity, 50% light interception plots. Therefore, above factors were mainly promoted the wilting phenomena of Yushin rice variety.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.1
• /
• pp.317-327
• /
• 2013

Air pollution and artificial heat of urban areas have caused the urban heat island in which asphalt pavements absorb solar heat during the daytime and release the heat at night. Hence, in order to improve the environment of urban areas, it is necessary to examine cooling pavements that can reduce heat on road pavements in urban areas. The application of temperature insulation paints on road pavements require to reduce black brightness for visibility, to increase the reflection rate of infrared light and minimize the reflection rate of visible light. In the study, one part of Acrylic-emulsion was used as a main binder, and the changes in black brightness and the changes of addition ratio (0%, 15%, 30%) of hollow ceramics, as well as kinds of paints (carbon black pigment, mixed mineral pigment) were selected as the main experimental factors. The performance of temperature reduction of cooling pavements was analyzed through the reflection rate of spectrum, the reflection rate of solar heat, and the lamp test. Abrasion resistance, UV accelerated weather resistance, and sliding resistance were tested in real situations. In addition, the performance of heat reduction of testing pavements covered with high-reflection paints was analyzed by using an infrared camera. As the test results, when using mixed mineral paints and hollow ceramic of 30%, the reflection rate of spectrum was 43% in the area of near-infrared ray and 17% in the area of visible light at black brightness of $L^*$=42.89 and the reflection rate of solar heat was 27.5%. Total color difference was ${\Delta}E$=0.27 in the test of UV Accelerated Weather Resistance, indicating almost no changes in color. BPN was more than 53 when scattering #2 and #4 silica sand of more than $0.12kg/m^2$. In Taber's abrasion resistance test, abrasion loss was up to 86.4mg at 500 rotations. The performance of heat reduction was evaluated using an infrared camera at the test section applying high-reflection paints to asphalt pavements, in which the results showed that the temperature was reduced by $12.7^{\circ}C$ on CI-30-40 cooling pavements ($L^*$=38.76) and by $14.2^{\circ}C$ on CI-30-60 cooling pavements ($L^*$=57.12).

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.20
• /
• pp.74-86
• /
• 1975

Experiments were carried out to know some physiological characters of several rice varieties such as Suweon 213-1, Suweon 214, Palkweng, Akibare and Nongbaek. In experiments, total standing crop, leaf area and total net production of dry matter were higher in the variety of Suweon 213-1 than the other varieties. RGR, NAR and CGR showed the highest at heading period of Suweon 213-1 than the other varieties. Efficiency of solar energy utilization also showed the highest through the entire growing period of Suweon 213-1. The amount of net production and dead parts could be estimated by the successive application of the productive structure.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.21 no.2
• /
• pp.187-202
• /
• 1976

Experiment were conducted to study the photosynthetic ability of several rice varieties and the influence of the drymatter production on the yield components of the rice plant, especially in ripening period. The photosynthetic ability at the ripening period, the varieties were classified into two groups as relatively high capacity and low capacity. With the earlier the transplanting date and the higher the N-content leaf blade, the greater the ratio of reserved assimilates befere heading time to the ear. This could be support the fact that the rate of full-ripened grains or grain yield of 'Tongil' variety may increased by the change of environment condition.condition.

• Journal of dental hygiene science
• /
• v.3 no.2
• /
• pp.83-88
• /
• 2003

Patient satisfaction is now recognized as a outcome indicator of health care quality. The objective of this research was to evaluate a patient satisfaction survey instrument specially applicable to dental care, and to examines the reliability and the effect of response biases on reported satisfaction. The acceptability of satisfaction as a quality indicators was qualified by several measurement problems. The patient questionnaire was administered in four different study samples to examine the consistency of data. Cronbach's alpha was used as the measure of internal consistency. A aquiesent bias was found in the sample of 80(20%) respondents. Response biases affacted level of measured satisfaction. Highly acquiesent respondents were older, less well educated than nonaquiesent subject.