• Journal of Korean Society for Atmospheric Environment
• /
• v.18 no.3
• /
• pp.193-204
• /
• 2002

To investigate the relationships between the atmospheric concentrations of PCBs and temperature, quantity of both parameters was performed at an urban site in Korea from July 1999 to January 2000. The strength of correlations between total PCB and temperature was found to be significant (r = 0.752, p < 0.001). It hence indicates that total PCB contents were affected sensitively by temperature change during the sampling period. The ratio of PCB homologs and Deca-CB(PCB 209) also behaved quite similarly to the change of temperature (r>0.60, p<0.05). This may be inferable with the progress of the gas/particle partitioning to the gas phase, especially for fri-and tetra-CBs. Because they have high vapor pressure, they generally exist in the gas phase. The Clausius-Clapeyron equation was applied to the atmospheric PCB data, relating PCB partial vapor pressure to inverse temperature. This may essentially represent the temperature-controlled transition between condensed phase and atmospheric gas phase. The slopes of the resulting plot with International Council for the Explanation of the Seas (ICES) congener ranged from -2810 to -5887, with significantly steep slope and $R^2$(p< 0.005) It was inferred that the PCB atmospheric concentration was also affected by change in the surrounding conditions such as soil, lakes and trees.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.12
• /
• pp.1151-1160
• /
• 2009

Perfluorinated compounds (PFCs) have been recognized as emerging environmental pollutants and are widely distributed all over the world. These compounds are hardly degradable and cause bioaccumulation and biomagnification during present for a long time in the environment: thereby after adversely biota and human bodies. It is difficult to remove PFCs using conventional water/wastewater treatment because of resistant property to photodecomposition, biodegradation and chemical decomposition. Moreover, domestic literature data on the pollution of PFCs in rivers and lakes are limited. In this paper, species, sources and risk of PFCs as well as behavior properties in drinking water/wastewater and treatment processes are demonstrated to encourage the domestic concern about PFCs.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.7
• /
• pp.38-48
• /
• 2003

Lake water quality assessment information is useful to anyone involved in lake management, from lake owners to lake associations. It provides lake water quality criteria, which can improve the ways how to manage out lake resources and how to measure current conditions. It also provides a knowledge base so that the lakes can be protected and restored. Here, the Freshwater Lake Water Quality Management System(FLAQUM) was developed. The results of FLAQUM application by scenario proved that pollutant load at rainfall by the nonpoint sources was much more than normal times at rainfall. From the result of Scenario I (pollutant source increase case), the concentrations of Boryeong freshwater lake were BOD 9.43mg/L, T-N 4.53 mg/L and T-P 0.21 mg/L, respectively, and those values exceed the standard of agricultural water. And in case of Scenario I and II(the present case) excluding Scenario III (pollutant source decrease case), all of T-N and T-P are either mesotrophication or eutrophication, on the other hand when 60% of pollution source is removed, the concentrations of Scenario III were BOD 3.21 mg/L, T-N 0.95 mg/L, T-P 0.11 mg/L, respectively, and which satisfies the standard of agricultural water quality.

• The Korean Journal of Quaternary Research
• /
• v.17 no.2
• /
• pp.75-78
• /
• 2003

This study is conducted to examine the solar radiation features of landscape in Eastern Mongolia and their space and time distribution characteristics. To many foreigners, the name Mongolia conjures up images of the vast steppes of Central Asia. And, indeed, the extensive grasslands of the steppe make up the heart of Mongolia-geographically and economically. Steppe covers nearly the entire far eastern part of Mongolia, extending west in a narrowing band just south of the Khangai and Khan Khokhii mountains all the way to the Depression of the Great lakes. Eastern Mongolia is recognized as one of the last remaining untouched grassland steppes in the world. Landscape of Eastern Mongolia divided by 19 types that belongs to High Mountain, Middle Mountain and low mountain steppe. Only 5.6% of the total land area is covered by forest. Eastern Mongolian steppe is homeland of migratory rare and endangered birds and about 2.0million freely migrating gazelles. According to Mongolian scientists, there is growing evidence of fundamental changes in the Eastern steppe ecosystems in terms of increasing aridity during the last 70 years. As estimated average annual temperature has increased by approximately 0.7oC, soil moisture, energy supply has been changing. These processes closely interrelated into water and energy cycle of steppe ecosystem.

• Journal of the Korean Institute of Rural Architecture
• /
• v.20 no.3
• /
• pp.1-9
• /
• 2018

This research aimed to identify walking trails' purpose of its use and the factors that influence the selection. For this, a survey targeting the walking trail users was conducted in 2016 to question the research aim stated above. The mean number of walking trail usage in a month was 2.51 times and the duration of use ranged from one to ten hours, with the average of 2.5 hours. The main reason for the usage was to maintain physical health and the following was for mental relaxation, thus showing more than 90% of the people concerned with physical and mental health. Walking trails near the residences had the greatest percentage and trails that include mountains, rivers, seas and lakes were the following. Trails near historical locations or countryside showed a lower percentage. The choices showed relevance to the proximity as a standard of selection. The next highest percentage was the convenience of transportation. Additionally, people that access the trails three or more times were inclined to be influenced by the installation of exercising equipment. The aspect of facilities showed that the place for relaxation was a significant selection factor such as bathrooms for 20s to 30s and exercising equipments for people older than 50. To access the walking trails, people reach it by automobiles, public transport, walking and bicycles and out of these, automobiles had the highest percentage.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.5
• /
• pp.970-976
• /
• 2004

In this paper, we analyze channel estimation algorithms in a RAKE receiver with MRC. There are 3 popular channel estimation algorithms, which are WMSA(Weighted Multi-Slot Averaging) algorithm, EGE(Equal Gain Estimation) algorithm, SSE(Symbol-to-Symbol Estimation) algorithm. We analyze asynchronous IMT-2000(3GPP) which employ 3 different channel estimation algorithms by HP-ADS(Advanced Design System) simulation tool. We used lakes fading channel model for the analysis. from simulation results, we could observe that the performance of WMSA algorithm is better than others in low Doppler effect(3Km/h). However, in the case of high Doppler effect(120km1h), the EGE algorithm is more efficient. In this case the simple estimator with EGE algorithm seems to be more useful.

• Journal of environmental and Sanitary engineering
• /
• v.14 no.4
• /
• pp.77-84
• /
• 1999

Most river quality problems are generated by pollutants which are discharged into the river as a consequence of human activities. And eutrophication occurs when water is over enriched with nutrients, principally nitrate and phosphate. Both these nutrients are found in many waste products, especially sewage even when the waste is treated. Eutrophication is concerned in lakes, but it also causes problems in river. Wide growth of Phytoplankton in rivers, leads to blockage of channels, but the main concern is deoxygenation because of the increase in plant life's demand for oxygen in revers. Fish, plant and animals die due to lack of oxygen. The increase of algae floating on the tops of water looks ugly and has attracted public attention and concern in recent years. One way of controlling eutrophication is to restrict the amount of waste carrying nitrate or phosphate from entering the water in the first place. another way is to remove it from the water after it has been entered. This study was carried out to investigate on the trophic state, nutrients and Chlorophyll-a concentration in the Han River. The results were as follows:1. Concentrations of total nitrogen were 2.208~9.221(5.133)mg/$\ell$2. Concentrations of total phosphate were 0.045~0.614(0.195)mg/$\ell$3. Chlorophyll-a concentration were $0.0-25.3(9.6)mg/m^3$.4. The correlation coefficient between T-P and Chlorophyll-a concentration was r=-0.856 at Sungsan sampling site.5. The correlation coefficient was r=-0.578~-0.767, between Paldang Dam outflow and Chlorophyll-a concentration at all sampling sites.

• Journal of Korean Society on Water Environment
• /
• v.28 no.2
• /
• pp.178-184
• /
• 2012

BOD decay rate is a key parameter of BOD-DO models in streams and lakes. In the calibration of water quality modeling appropriate range of coefficient is required for guidance of parameter selection. In this study BOD decay rate was measured at 48 stream sites and 10 reservoir sites in 8 different river systems. The decay rate ranged from 0.09 to 0.25 $day^{-1}$ with a mean of 0.16 $day^{-1}$. Among river systems the decay rates showed significantly different ranges, with the Han River system showing higher values than other river systems. In comparing different types of water bodies, the decay rate was slightly higher in tributaries than in reservoirs and mainstreams. Our results can provide guidance to the selection of proper coefficient for various water bodies in the calibration of water quality models.

• Water for future
• /
• v.29 no.5
• /
• pp.235-244
• /
• 1996

A one-dimensional eddy diffusion model and a mixed-layer model are developed and applied to simulate the vertical temperature profiles in lakes. Also the running results of each method are compared and analyzed. In an eddy diffusion model, molecular diffusivity is neglected and eddy diffusivity which does not need lake-specific fitting parameter and constant lake's level are applied. The heat exchanges at the water surface and the bottom are formulated by the energy balance and zero energy gradient, respectively. In a mixed-layer model, two layers approach which has a constant thickness is adopted. Application of these models which use explicit finite difference an Runge-Kutta methods respectively demonstrates that the models efficiently simulate water temperatures.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2018.10a
• /
• pp.42-42
• /
• 2018

Two unrecognized species of Sparganium of Korea were found during the our field expeditions and phylogenetic analyses of specimens deposited in the Herbarium of Korea National Arboretum (KH). S. coreanum H. $L{\acute{e}}v$. was first reported as a new species based on the specimen (Taquet, 2150) collected from Jeju Island. It has been recognized as synonym or infraspecific taxa of S. stoloniferum and S. eurycarpum or even never recognized recently. However, phylogenetic tree showed that S. coreanum is monophyletic and has sister relationship with S. eurycarpum. Furthermore, additional distribution localities were also found by herbarium survey. Morphological characteristics and distribution information of S. coreanum will be discussed. Another Sparganium species found from Mt. Daeam is occurring either as floating or emergent. Although we could not identify this species since lack of any flowers or fruits for two year surveys, phylogenetic analyses results showed that this species belong to the clade of S. glomeratum, which is distributed in high elevation lakes and marshes of Europe, Asia, and North America. Additional survey of morphology and report will be needed.