• Journal of Environmental Health Sciences
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• 제33권5호
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• pp.451-455
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• 2007

This study was performed to evaluate the effects of input ratios of bulking material in aerobic composting of food wastes on variation of colony forming units(CFU) of fungi. Wood chips were used as a bulking material. Volume ratios of food wastes to wood chips in reactor of Control, WC-1 and WC-2 were 10/0, 10/5 and 10/10, respectively. Reactors were operated for 24 days with I hour stirring by 1rpm and 2 hours of the forced aeration rate of $80L/min{\cdot}m^3$ per day. WC-2 reached high temperature range faster than WC-1, and the maximum temperature of WC-2 was higher than that of WC-1. WC-2 reached high pH range faster than WC-1. and the maximum pH of WC-2 was higher than that of WC-1. WC-2 reached high Log(CFU/gram) range faster than WC-I, and the maximum Log(CFU/gram) of WC-2 was higher than that of WC-1. These all mean that the reaction velocity of composting of WC-2 was faster than that of WC-1. The profile of fungi changes in Log(CFU/gram) was similar to that of temperature changes (r=0.8861) not pH changes (r=0.1631).

• The Korean Journal of Ecology
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• 제28권3호
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• pp.121-127
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• 2005

To reveal vegetation history and environmental changes in Mt. Jiri, sediment cores were collected from Wangdeungjae moor of Mt. Jiri. Overall dry matter accumulation rates and sedimentation rates by $^{14}C-dating$ were 0.027 $kg{\cdot}m^{-2}{\cdot}yr^{-1}$ and 0.184 mm/yr since 1250 ($760{\pm}40$ yrs BP, 14 cm in depth). There are three pollen zones; the first zone is below 14 cm depth where Quercus dominated, the second zone is from 14 cm to 6 cm depth where Gramineae increased and Quercus and Salix dominated and the third zone is from 6 cm depth to the top where Pinus and Quercus dominated. Total pollen concentration gradually increased from bottom to the top of sediment core, which implies wet, anaerobic and cool condition during covered period by the core. Calcium and magnesium contents had increased since 14 cm depth, with peaks at 13 and 20 cm depths. This indicates that groundwater had recently become relatively more important than surface water as water source of Wangdeungjae moor Exotic plant or Chenopodiacea pollen was less than 1%. There was little variation in total N and P contents along the length of the core. These results support that Wangdeungjae moor has been little affected by anthropogenic activities. Also, nutrients and heavy metal contents indicate the baseline condition of Wangdeungjae moor.

• Journal of Environmental Science International
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• 제22권3호
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• pp.379-383
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• 2013

This study was conducted to investigate the changes in nitrogen and soluble reactive phosphorus(SRP) contents from hanwoo manure using probiotics to feed and manure additives during 5 weeks. A total of 45 hanwoo(24 months old) with averaging $580{\pm}20$ kg in weight were randomly assigned to 3 dietary treatments with 3 replicates per treatment(5 hanwoo per pen, $5{\times}8m$). The treatment were supplemented, control, T1(10 kg roughage + 2 kg concentrate(2% probiotics as-fed basis)), and T2(10 kg roughage + 2 kg concentrate(2% probiotics as-fed basis) + 7 kg probiotics on the surface of hanwoo manure (top-dressing)). During the experimental period, there were statistically significant differences(P<0.05) in pH values at 3 and 5 weeks; TN contents at 5 weeks; and SRP contents at 5 weeks in all treatments. Adding probiotics to feed or feed and manure increased manure pH in comparison with controls. As time increased, changes in TN contents decreased in the order: T2 > Control > T1. Especially, the reduction in SRP contents in all treatments at 5 weeks was in following order: T1 > T2 > Control. This result suggests that it is possible to make efficient use of probiotics as feed and manure additives for reducing environmental pollution or to provide fundamental information on livestock managements to producers.

• Journal of Environmental Impact Assessment
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• 제5권1호
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• pp.31-45
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• 1996

This paper presents the results from a hydrodynamic model study to predict the impacts of coastal reclamation in Pusan harbor system using RMA2 which is a tidal flow model of the US Army Corps of Engineers' TABS-2 system. A finite element mesh was constructed and refined to cover the complicated geometry of Pusan harbor system and the proposed reclamation area. The model was calibrated to tidal elevations and currents measured during spring fall syzygys. Under the three different tidal conditions including summer winter syzygys, spring fall quarters, and summer winter quarters, the model predictions were compared with the field measurements both in tidal elevation and current. In all cases, there were excellent agreements between the model predictions and the field measurements. The validated model was then used to predict the changes in tidal current and elevation that might occur due to the coastal reclamation. It was predicted that there would be no change in tidal elevation of this system after the reclamation. In tidal current, however, discernible changes were predicted near the proposed reclamation area both in magnitude and direction.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.105-110
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• 2006

The most sensitive part of the installed optical cable is the optical loss variation of the splicing point according to the environmental changes. This paper presents the details of the experimental results of the external environmental changes on optical loss, such as bending, temperature variation, temperature variation after water osmosis and variation. Through the bending test of optical fiber, rapid increase of optical loss was measured within the diameter of 30mm. The result of optical loss variation within the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$ is less than 0.02dB. It was confirmed that the maximum optical loss increased up to 0.2dB in case of water osmosis within the temperature range of $-40^{\circ}C{\sim}80^{\circ}C$. There is small optical loss variation of 0.01dB under the 1mm vibration test. The experimental results of this paper can be used as the reference data for the design of the optical fiber cable splicing enclosure to protect the optical loss variation due to environmental changes.

• Journal of the Korean Operations Research and Management Science Society
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• 제41권1호
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• pp.55-69
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• 2016

In response to drastic environmental changes, companies have been continuously rebalancing their resources and capabilities to sustain their competitive status or to survive difficult times. The aim of this study is to analyze the effect of sudden environmental changes on the competitive status of a firm and to identify the internal factors that differentiate sustainer and non-sustainer groups. To achieve this goal, we selected 85 representative IT and non-IT companies from the S&P 500 companies and investigated them with respect to the change in their five-year competitive status since the 2008 global financial crisis. As a concrete performance measure, the concept of perceived competitive status (PCS) was introduced, and four distinct PCS categories were identified by using the stock price changes during the selected period. The four distinct PCS categories are "sustaining," "drifting," "deep sunken," and "bouncing back." Discriminant analysis was performed on these four distinct PCS categories. The empirical study conducted showed that revenue and cost efficiency are the most discriminating factors, especially in the economic recovery period. In particular, stronger financial liquidity was observed in high-performing "bouncing back" companies than in the other category companies.

• Journal of Environmental Impact Assessment
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• 제15권1호
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• pp.67-78
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• 2006

Global warming brings about changes of diverse environmental, especially changes of plant distribution. The purpose of this paper is to examine the relationship between temperature rise and changes of northern limit of vegetation growth in Korea. Bamboos (Phyllostachys) and boundary between the northern type and southern type of garlic (Allium sativum L.) were selected. The data of the distributions of bamboos and garlic are collected by field survey and interviews. Temperature is analyzed from 1904 to 2000. The northern limit of Phyllostachys moves 60-100 km northward, for about 100 years, the period of 1907-2003 and mean temperature of Korea increases about $2^{\circ}C$ during the same period. It means that the northern limit moves 30-50 km northward, for each $1^{\circ}C$ rising of January mean temperature. The boundary between the northern type and southern types of garlic moves northward 40-140 km from 1980s to 2000. The moving width is broad in the west coastal region while the width is narrow in the inland and mountain regions. The mean moving width is about 100 km.

• Atmosphere
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• 제31권1호
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• pp.61-71
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• 2021

The relationship between the Arctic Oscillation (AO) and surface air temperature (SAT) over Korea is re-examined using the long-term observation and reanalysis datasets for the period of December 1958 to February 2020. Over the entire period, Korean SAT is positively correlated with the AO index with a statistically significant correlation coefficient, greater than 0.4, only in the boreal winter. It is found that this correlation is not static but changes on the decadal time scale. While the 15-year moving correlations are as high as 0.6 in 1980s and 1990s, they are smaller than 0.3 in the other decades. It is revealed that this decadal variation is partly due to the AO structure change over the North Pacific. In the period of 1980s-1990s, the AO-related sea level pressure fluctuation is strong and well defined over the western North Pacific and the related temperature advection effectively changes the winter SAT over Korea. In the other periods, the AO-related circulation anomaly is either weak or mostly confined within the central North Pacific. This result suggests that Korean SAT-AO index relationship, which becomes insignificant in recent decades is highly dependent on mean flow change in the North Pacific.

• Journal of Korean Society on Water Environment
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• 제38권1호
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• pp.1-9
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• 2022

The Yeongsan River, one of the four major rivers in Korea, shows the highest degree of water pollution compared to the other major rivers. The construction and opening of two weirs, Seungchon and Juksan, induced fluctuations in the hydrologic conditions and water quality of the river. To investigate the water quality changes caused by the opening of the weir in 2017, this study analyzed the water quality data using the non-parametric Wilcoxon signed-rank test and the three-dimensional spatiotemporal plots. The non-parametric statistical test results showed that the concentration of all parameters has increased after 2017 at a significance level of 0.05. For the parameters that showed the highest degree of change, chlorophyll-a and suspended solids, the median values have increased by more than 30% after weir opening. Visual analysis additionally showed the spatial changes in the Yeongsan River. Generally, the sites above the Seungchon weir showed higher pollution levels than those above the Juksan weir. In time series, visual analysis results also showed the trend of rising concentration for all water quality parameters, indicating that the opening of two weirs had a significant effect on the change in water quality of the Yeongsan River.

• Journal of the Korean Society of Clothing and Textiles
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• 제46권3호
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• pp.390-406
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• 2022

This study aims to establish the optimal environmental conditions for storing textile products. Four textile products (cotton, wool, nylon, cotton/polyurethane) were used to produce experimental fabrics according to artificial contamination and washing conditions. Each fabric was subjected to three environmental conditions (A: 20-25℃/20% RH, B: 20-25℃/50% RH, C: 30-35℃/65% RH) for 4-12 weeks. Changes in textile characteristics include tensile strength, wrinkle recovery rate, and odor intensity. Results show that the change in tensile strength for the four test fabrics slightly decreased with a storage time of 4 to 12 weeks. The wrinkle recovery rate of the fabrics was the lowest under the C condition. UV exposure causes a substantial decrease in the tensile strength of the textiles. The change in odor characteristics was the highest for the odor intensity in the C condition. For storing textile products for sustainable management, it is desirable to maintain a temperature of 20 to 25℃ with a relative humidity of 50% RH or less and to provide ventilation in an enclosed storage space that can also block UV rays.