• Journal of Environmental Science International
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• v.16 no.5
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• pp.593-602
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• 2007

The frequency of tropical nights and tropical days in Busan during summer season (June-August) from 1995 to 2004 were investigated. When air temperature higher than $25^{\circ}C$ continuously maintains at night in summer, it is called the occurrence of tropical night. Tropical day is defined that maximum air temperature is higher than $30^{\circ}C$, In Jin-Gu and Daeyeon-dong shows a lot of frequency of tropical day and tropical night because there were located in downtown. Relatively, the areas where are located in seaside and riverside show very low frequency. This can be explained the cooling effects of sea and river. The main meteorological characteristics during tropical nights and tropical days is proved pattern of reverse tendency through wind rose. We analyzed heat index and discomfort index during tropical night and tropical day. This study is useful to understand the aspect of urban thermal environment but need some more observation to quantify.

• Journal of the Korean housing association
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• v.14 no.1
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• pp.19-27
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• 2003

This study aims to survey the living spaces of the welfare facilities for the aged to get the objective relationships between the physical thermal environment and the users' subjective responses. The surveys were made twice in winter and once in summer during 2001 and 2002. An ambient temperature, relative humidity, air velocity, globe temperature were measured as physical elements of thermal environment and the ASHRAE Psychophysical Voting Scale were used as an evaluation index for subjective responses. As the results, the aged respond thermally comfortable, in spite of the differences among important factors such as thermal sensations, humidity sensations and air velocity sensations. Also the physical thermal environmental elements and the subjective responses indices exceed thermal comfort range calculated by PMV(Predicted Mean Vote) and PPD(Predicted Percentage Dissatisfied). It shows that the insulation of walls of the facilities is not enough for heating and cooling seasons, and the indoor environmental control is necessary.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.2
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• pp.5-13
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• 2020

This study was conducted to evaluate the effect of optimal aeration time of livestock manure slurry with fruits pomace on germination index. Six co-digestates of livestock manure slurry with fruits was aerated with 0.1 ㎥ air/㎥·min for 54 days. The maturity of digestates was evaluated using the germination method. The germination index(GI) of co-digestate of SS + CS + MP was more than 70 at the 30th day of aeration. The GI of co-digestate of SS + CS was more than 70 at the 36th day of aeration. The GI of digestate of swine manure slurry alone was 70 at the 54th day of aeration. The co-digestate of SS + MP caused to shorten 24 days of aeration period to reach GI of 70, compared to swine manure digestate. These results suggest that the germination index of seed could be used to establish the optimal aeration time for co-digestate of liquid fertilizer.

• Korean Journal of Environment and Ecology
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• v.7 no.2
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• pp.252-269
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• 1994

This study was conducted to the early diagnosis of injuries on needles of conifer by acid rain and air pollutants in metropolitan area, Korea. It was executed to calculate of injured index, contact angle measurement, nutrient content analysis in needles, analysis of soil chemical properties from June 1990 to June 1991. The sensitive species (Picea abies, Abies holophylla) for acid rain and air pollutants were used as the study materials. And the results from this study were as follows : Degree of Injured index was divided into three groups in June 1990. The first group (not injured sites) was Kwangnung and Yangpyung. The Second group (slight injured sites) was Inchon, Boramae Park, Kwachun, Seoul Women's Univ., Anyng, and Yangsuri. The third group (serious injured sites) was Namsan, Seoul City Univ., Children's Park, and Kumgok Royal Tomb. But, Inchon, Kwachon area were changed from slight injured areas to serious injured areas in December 1990. As time goes on, the degree of injured gets worse. In contact angle analysis, value of December 1990 was lower than that of June 1990, especially, that of two-year-needle were lower than of one-year-needle. The correlation between injured Index and contact angle was significantly negative. In the result of needle nutrients analysis of Picea abies, Abies hozophylla, Ca, Mg, K contents was higher in December 1990 than that in June 1991 and that of one-year-needle were prominantly higher than that of two-year-needle. In case of wax quantity analysis in injured area, the older the leaf age is, the smaller the contented wax quantity is. In injured area, the higher a leaf age is, the much that of index is. As a result, the method of analysis referred in the former, is applied by a complementary cooperation. That of method is done sustainably in the future, the correct results will be expected.

• Asian Journal of Atmospheric Environment
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• v.9 no.1
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• pp.12-21
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• 2015

Air pollution is a challenging issue in some of the large cities in developing countries. In this regard, data interpretation is one of the most important parts of air quality management. Several methods exist to analyze air quality; among these, we applied the Multilayer Perceptron (MLP) and Radial Basis Function (RBF) methods to predict the hourly air concentration of benzene in 14 districts in the municipality of Tehran. Input data were hourly temperature, wind speed and relative humidity. Both methods determined reliable results. However, the RBF neural network performance was much closer to observed benzene data than the MLP neural network. The correlation determination resulted in 0.868 for MLP and 0.907 for RBF, while the Index of Agreement (IA) was 0.889 for MLP and 0.937 for RBF. The sensitivity analysis related to the MLP neural network indicated that the temperature had the greatest effect on prediction of benzene in comparison with the wind speed and humidity in the study area. The temperature was the most significant factor in benzene production because benzene is a volatile liquid.

• Journal of Environmental Science International
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• v.30 no.8
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• pp.621-628
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• 2021

The characteristics of time changes in air temperature, DI (discomfort index) and WBGT (wet-bulb globe temperature) were investigated for inland city (daegu) and coastal city (pohang) of Gyeongbuk Province during the 2018 consecutive heat wave season. The time when the temperature dropped below 33℃ was around 19h in both regions. As such, the two regions were similar with respect to the time up to which the heatwave warning levels continued. However, the discomfort index (DI) was higher than 27 in Pohang. Most people feel unpleasant when an discomfort index of 27 or higher appears. The results indicated that Korea's night-time thermal environment during the summers is particularly poor in the southern coastal areas. WBGT began at 09:00 and lasted until 21:00, with a score of 31 or higher; this score, in principle, corresponded with the duration of outdoor activity in both regions. Therefore, it was found that outdoor work was at a level where all day long had to be stopped in both areas during the heat wave. Although time changes in temperature and WBGT were similar in both regions, Discomfort Index (DI) differed significantly. The difference refers to the fact that Pohang is strongly affected by the high heat capacity effect and the supply of water vapor from the sea.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.32-41
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• 1999

Natural gas is an attractive fuel in view of environment benefits due to its flow carbon-to-hydrogen ratio. However, its compositions and properties are varied depending upon production regional groups. Therefore, study on the combustion characteristics of natural gas engines with a variety of compositions has been demanded for the efficient application of gas engines. This study aims to investigate the effects of gas composition on engine combustion characteristics. It was found that , by controlling an engine with fixed fuel nozzle area, power and heat release were subject to Wobbe Index. And at fixed excess air ratios, power and heat release were subject to low heating value of unit mixture . In addition, in case of constant nozzle area, combustion duration was found to be inversely proportional to CP(Combustion Potential), and the condition of fixed excess air ratios showed no change in combustion duration, regardless of CP.

• Journal of Biosystems Engineering
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• v.25 no.1
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• pp.63-70
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• 2000

In Korea, researches for year-round leaf vegetables production system are in progress and the most of them are focused on environment control. Automation technologies for harvesting , transporting and grading need to be developed. This study was conducted to develop harvesting process automation system profitable to a competitive price. 1. Manipulator and end-effector are to be designed and fabricated , and fuzzy logic controller for controlling these are to be composed. 2. The entire system constructed is to be evaluated through a performance test. A robot system for harvesting a lettuce was developed. It was composed of a manipulator with 20DOF (degrees of freedom) an end-effector, a lettuce feeding conveyor , an air blower , a machine vision device, 6 photoelectric sensors and a fuzzy logic controller. A fuzzy logic control was applied to determined appropriate grip force on lettuce. Leaf area index and height index were used as input parameters, and voltage was used as output parameter for the fuzzy logic controller . Success rate of the lettuce harvesting system was 93.06% , and average harvesting time was about 5 seconds per lettuce.

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1589-1595
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• 2016

From December 2014 to November 2015, an automatic weather system (AWS) was installed over a wide road of Daegu to continuously measure meteorological factors and surface temperature. We investigated the effective operating period of the clean-road system using the daily maximum and minimum air and asphalt surface temperatures, with the aim of creating an optimum thermal environment. The clean-road system was installed over a part of the broad way of Dalgubul(Dalgubul-Daero) by Daegu Metropolitan City in 2011. Until now, the clean-road system has been operated from the middle of April to the end of September. We assumed that it was desirable that the clean-road system could be operated when the discomfort index was above 55. In conformity with the conditions, we concluded that the optimum operation period of the clean-road system is from the end of March to about the middle of October.

• Current Optics and Photonics
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• v.7 no.2
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• pp.136-146
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• 2023

Based on calculations using the macroscopic Maxwell's equations with mesoscopic boundary conditions, light absorption by a layered metal-insulator-metal (MIM) metamaterial system embedded in three different environments is investigated. Increasing the top metal thickness shifts the broad absorption band to lower dielectric-constant regions and longer wavelengths, for either TM or TE waves. Boosting the dielectric-layer thickness redshifts the broadband absorption to regions of larger dielectric constant. In air, for the dielectric-constant range of 0.86-3.40, the absorption of the system exceeds 98% across 680-1,033 nm. In seawater with optimized dielectric constant, ≥94% light absorption over 400-1,200 nm can be achieved; particularly in the wavelength range of 480-960 nm and dielectric-constant range of 0.82-3.50, the absorption is greater than 98%. In an environment with even higher refractive index (1.74), ≥98% light absorption over 400-1,200 nm can be achieved, giving better performance. The influence of angle of incidence on light absorption of the MIM system is also analyzed, and the angle tolerance for ≥90% broadband absorption of a TM wave is up to 40° in an environment with large refractive index. While the incident-angle dependence of the absorption of a TE wave is nearly the same for different circumstances, the situation is different for a TM wave.