• Journal of Environmental Impact Assessment
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• v.7 no.2
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• pp.135-143
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• 1998

In order to study the general characteristics of reservoir and stream sediments, various analysis tests were conducted. Water contents and ignition loss were measured to know the primary sediment characteristics. The COD, total phosphorus and nitrogen were contained for the determination of organic substance content. For the purpose of establishing the contamination degree of heavy metals, some heavy metal contents were investigated. In heavy metal contents, reservoir sediments showed somewhat higer value than stream sediments. As a result, the reservoir sediment content of all analysis items were higher than stream sediment.

• Journal of Environmental Impact Assessment
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• v.19 no.5
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• pp.483-495
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• 2010

The passenger pigeon (Ectopistes migratorius) was a species of pigeon that was once the most common bird in North America. According to some ornithologists, the number of passenger pigeons is estimated as many as five to six billions at the time when the first Europeans arrived there. But this species became extinct in 1914. There were a multiplicity of causes in the extinction; first, the extension of telegraph lines and railroads into the Middle West of the USA beginning in 1850s, second, the loss of vast feeding, nesting, and roosting sites of the passenger pigeon due to the massive deforestation, third, the rapid population growth of the USA during nineteen century, fourth, the commercial exploitation of the species, and finally, the infirm and weak protective efforts. Some important lessons can be learned from the extinction of the passenger pigeon. First, it shows how much critical the public interest is for a successful conservational movement. Second, it illustrates the need for strong laws and practices in the protection of an endangered species from going extinct. Third, the fate of the passenger pigeon proves a very important principle in conservational biology. That is, for each species (bird or other animal) there is a minimum population to sustain the species. Ecologists generally believe that the extinction of the passenger pigeon was due to the loss of their numbers below the minimum owing to overexploitation.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.314-320
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• 2008

During the summer season, more than half of the annual precipitation in Korea occurs during the summer season due to the geographical location in the Asian monsoon belt. So, this causes severe soil erosion from croplands, which is directly linked to the deterioration of crop/land productivity and surface water quality. Therefore, much attention has been given to develop accurate estimation tools of soil erosion. The aim of this study is to assess the performance of using the empirical Universal Soil Loss Equation (USLE) and the physical-based model of the Water Erosion Prediction Project (WEPP) to quantify eroded amount of soil from agricultural fields. Input data files, including climate, soil, slope, and cropping management, were modified to fit into Korean conditions. Chuncheon (forest) and Jeonju (level-plain) were selected as two Korean cities with different topographic characteristics for model analysis. The results of this current study indicated that better soil erosion prediction can be achieved using the WEPP model since it has better power to illustrate a higher degree of spatial variability than USLE in topography, precipitation, soils, and crop management practices. These present findings are expected to contribute to the development of the environmental assessment program as well as the conservation of the agricultural environment in Korea.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.1
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• pp.40-47
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• 2003

This paper discussed the assessment of hand of Tencel denim fabrics finished by enzymatic hydrolysis. The subjective hand and the preference of Tencel denim fabrics were evaluated using the developed scale. The factors affecting consumers taste for Tencel denim fabrics were analyzed by statistics using SAS program. Also, the effects of cellulase treatment on the properties of Tencel denim fabrics were evaluated by the subjective hand measurements. The results are as follows: As the weight loss increased. fabrics were evaluated as finer, smoother, softer, warmer, more refined (surface properties), more compact and weaker (durability), more flexible, flossier, lighter, softer, thinner (sense of weight), more elastic, and less wrinkly (shape recovery). Fabrics were evaluated to have the dry touch regardless to the rate of weight loss (moisture properties). Overall hand preference of Tencel denim fabrics was in the side of not preferred. Hand of Tencel fabrics seems not to appeal to Korean people. Color preferences were not significantly different among five groups. The correlations between subjective hand and preference showed that fine, smooth, flexible, warm, refined, loose, soft, dry touches were preferred in Tencel denim fabrics.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1258-1270
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• 2009

Recently, the earthquakes activities are more of frequency occurred in the country. In case of nomal or large magnitude earthquakes, which cause a rising number of life loss or widespread loss of property. It must be considered how to cope with the situperty of dpmage in the country ty account of ay earthquake. Consequently, the public works have currently ensured against a lot of risk about seismism not only on large scale structures but also relatively small structures. Therefore, in this study, in order to make the seismic stability safe, it has been evaluated by the seismic performance for caisson-type breakwater. The seismic response analyses have conducted on the caisson-type breaker under long-period, short-period and artificial seismic wave. The liquefaction potential of the foundation, which is caisson-type, is also estimated by using the simplified assessment method. Finally, the result of the numerical analysis by PENTAGON 2D finite element method(FEM) program are presented for 3 cases with time-history seismic analysis under the seismic load.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.466-473
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• 2007

The comparison for the performance of heating systems, district heating and separate heating and power, is carried out in terms of energy consumption and environment on the basis of real operating data. The efficiency of boiler and the heat loss within the housing are assumed with reasonable manner due to the lack of reliable data regarding those quantities. The assessment for the established criteria of previous studies is performed and the new criteria for the analysis is proposed. It is shown that the district heating system is superior to the separate heating and power system from the point of view of reduction of energy use and environment improvement. The sensitivity study for those quantities with uncertainty such as the boiler efficiency and heat loss within the housing is carried out also and the reasons for the analysis results are discussed in detail.

• Journal of Environmental Impact Assessment
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• v.22 no.4
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• pp.329-343
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• 2013

According to previous studies, the increased air temperature can lead to change of thermal stratification structure of lakes and reservoirs. The changed thermal stratification may result in alteration of materials and energy flow. The objective of this study was to predict the effect of climate change on the water temperature and stratification structure of Daecheong Reservoir, located in Geum River basin of Korea, using a three-dimensional(3D) hydrodynamic model(ELCOM). A long-term(100 years) weather data set provided by the National Institute of Meteorological Research(NIMR) was used for forcing the 3D model. The model was applied to two different hydrological conditions, dry year(2001) and normal year(2004). It means that the effect of air temperature increase was only considered. Simulation results showed that the surface water temperature of the reservoir tend to increase in the future, and the establishment of thermal stratification can occur earlier and prolonged longer. As a result of heat flux analysis, the evaporative heat loss can increase in the future than now and before. However, the convective heat loss and net long wave radiation from water surface decreased due to increased air temperature.

• Journal of the Society of Disaster Information
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• v.11 no.3
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• pp.356-364
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• 2015

As the modern society becoms industry acceleration and urbanization. Disaster is noticed that loss of life and a huge property loss. In sprit of continuous experience misfortune that reality have nonhigh national consciousness. But government is on the brink of various disaster. Various disaster are becoming larger and larger through industrialization and abnormal climate. The researchers of the study suggest as followers: the selection of a key risk factors throuh vulnerability analysis and risk assessment of disaster. As well suggest as policy direction throuh plan of personalized safety management.

• Journal of Navigation and Port Research
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• v.41 no.5
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• pp.259-268
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• 2017

Formal Safety Assessment (FSA) has been mostly implemented on the hardware aspects of vessels. Although there are guidelines regarding human error FSAs, there have not been many assessments in such areas. To this end, this study seeks to use precedent studies for the safe operation of DP vessels, conducting an FSA regarding human error of DP LOP (Loss of Position) incidents. For this, the study referred to precedent studies for the frequency of DP LOP incidents caused by human errors, adding the severity of LOP incidents, and then applying them to the Bayesian network. As a result, the study was able to confirm that among DP LOP incidents caused by human errors, the drive-off from skill-based errors was 74.3% and the drive-off from unsafe supervision was 50.5%. Based on such results, RCOs (Risk Control Options) were devised through a brainstorming session with experts coming up with proposals including providing mandatory DPO training, installing DP simulator on the vessels, drawing up measures to understanding the procedures for safe operation of DP vessels. Moreover, it was found that mandatory DPO training is reasonable in terms of cost benefits and that while installing a DP simulator is not suitable in terms of cost benefits, it can significantly reduce risks when operating DP vessels.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.873-879
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• 2024

A sodium-cooled fast reactor (SFR) core has a potential of prompt criticality due to a change of core material distribution during a severe accident, and the resultant energy release has been one of the safety issues of SFRs. In this study, the safety assessment of an unprotected loss-of-flow (ULOF) in a small SFR (SSFR) has been performed using the SIMMER-IV computer code, which couples the models of space- and time-dependent neutronics and multi-component, multi-field thermal hydraulics in three dimensions. The code, therefore, is applicable to the simulations of transient behaviors of extended disrupted core material motion and its reactivity effects during the transition phase (TP) of ULOF, including a potential of prompt-criticality power excursions driven by fuel compaction. Several conservative assumptions are used in the TP analysis by SIMMER-IV. It was found out that one of the important mechanisms that drives the reactivity-inserting fuel motion was sodium vapor pressure resulted from a fuel-coolant interaction (FCI), which itself was non-energetic local phenomenon. The uncertainties relating to FCI is also evaluated in much conservative way in the sensitivity analysis. From this study, the ULOF characteristics in an SSFR have been understood. Occurrence of recriticality events under conservative assumptions are plausible, but their energy releases are limited.