• Economic and Environmental Geology
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• v.38 no.5 s.174
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• pp.535-545
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• 2005

Environmental survey from some abandoned metal mine areas was undertaken on to assess the risk of adverse health effects on human exposure to arsenic influenced by past Au-Ag mining activities. Elevated levels of As were found in tailings from the studied mine areas. This high concentration may have a impact on soils and waters around the tailing piles. In order to perform the human risk assessment, chemical analysis data of soils, rice grains and waters fur As have been used. The HQ values fer As via the rice grain and groundwater consumption were significantly higher compared with other exposure pathways in all metal mine areas. However, there were minimal soil and water dermal contact risks. The resulting Hl values of As from the Dongil, Okdong and Hwacheon mine areas were higher than 5.0, and their toxic risk due to drinking water and rice grain was strong in these mine areas. The cancer risk of being exposed to As by the rice grain route from the Dongil, Okdong and Hwacheon mine areas was $5.2\times10^{-4},\;6.0\times10^{-4}\;and\;8.1\times10^{-4}$, respectively. The As cancer risk via the exposure pathway of drinking water from these mine areas exceeded the acceptable risk of 1 in 10,000 fer regulatory purposes. Thus, the daily intakes of groundwater and rice grain by the local residents from the Dongil, Okdong and Hwacheon mine areas can pose a potential health threat if exposed by long-term arsenic exposure.

• Journal of Environmental Science International
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• v.9 no.3
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• pp.223-228
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• 2000

The purpose of this study is to evaluate the purification capacity of pollutants by column test with the tidal flat sediment. Sediment materials were taken from Chunjangdae tidal flat which located in Chungnam Seochungun. The column tests were conducted on four conditions(R1 : raw sewage filtered by G2 filter, R2 : sterilized sewage after filtered by GF/C filter, R3 : R2 /filtered(membrane) seawater (1:1), R4 : R2 /filtered(membrane) seawater(1:2)). The results of this study may be summarized as followed ; The removed COD by column tests were increased according to increasing the quantity of sewage. During the column tests of 580min, the total removed ammonia nitrogen were 90.1mg for R1, 81.0mg for R2, 27.6mg for R3 and 4.1mg for R4. The result was similar to COD experiment. During the 580min, the total removed total-phosphates were 3.4mg for R1, 4.2mg for R2, 5.6mg for R3 and 2.0mg for R4. The removal efficiency of Pb and Cd for R3 and R4 reactor were higher than R1 and R2 reactor. The remove of heavy metal by the column test was high in sample with seawater. But in the initial 20min, the adsorbed Pb and Cd showed about 3% of the total adsorbed Pb and Cd during 580min.

• Membrane Journal
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• v.21 no.1
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• pp.22-29
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• 2011

During the maintenance, repair and replacement process of circuit breaker, $SF_6$ reacted with input air in arc discharge, which led to the production of by-product gases (eg, $N_2$, $O_2$, $CF_4$, $SO_2$, $H_2O$, HF, $SOF_2$, $CuF_2$, $WO_3$). Among these various by-product gases, $N_2$, $O_2$, $CF_4$ is major component. Therefore, the effective separation process is necessary to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. In this study, the membrane separation process was applied to recycle the $SF_6$ gas from the mixture gas containing $N_2$, $O_2$, $CF_4$. The concentration of $SF_6$ gas in gas produced from the electric power industry is over than 90 vol%. Therefore, we made the simulated gas containing $N_2$, $O_2$, $CF_4$, $SF_6$ which the concentration of $SF_6$ gas is minimum 90 vol%. From the results of membrane separation process of $SF_6$ gas from $N_2$, $O_2$, $CF_4$ $SF_6$ mixture gases, PSF membrane shown the highest recovery efficiency 92.7%, in $25^{\circ}C$ and 150 cc/min of retentate flow rate. On the other hand, PC membrane shown the highest recovery efficiency 74.8%, in $45^{\circ}C$ and 150 cc/min of retentate flow rate. Also, the highest rejection rate of $N_2$, $O_2$, $CF_4$ is 80, 74 and 58.9% seperately in the same operation condition of highest recovery efficiency. From the results, we supposed the membrane separation process as the effective $SF_6$ separation and recycle process from the mixture gas containing $N_2$, $O_2$, $CF_4$, $SF_6$.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.53-65
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• 2014

In order to estimate the effect of nutrients addition for phytoplankton growth and community compositons in spring and summer season, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas in Gwangyang Bay, Korea. Nutrient additional experiments were also conducted to identify any additional nutrient effects on phytoplankton assemblage using the surface water for the assay. Bacillariophyceae occupied more than 90% of total phytoplankton assembleges. Of these, diatom Eucampia zodiacus and Skeletonema costatum-like species was mainly dominated in spring and summer, respectively. Here, we can offer the season why the two diatom population densities were maintained at high levels in both seasons. First, light transparency of spring season in the euphotic zone was greatly improved in the bay. This improvement is one of important factor as tigger of increase in E. zodiacus population. Second, low salinity and high nutrient sources supplied by Seomjin River discharge are a main cue for strong bottom-up effects on S. costatum-like species during the summer rainy season. Based on the algal bio-assays, although maximum growth rate of phytoplankton communities at inner bay (St.8) were similar to those of outer bay (St.20), half-saturation constant ($K_s$) for phosphate at outer bay was slightly lower than those of inner bay. This implied that adapted cells in low nutrient condition of outer bay may have enough grown even the low phosphate and they also have a competitive advantage against other algal species under low nutrient condition. In particular, efficiency of N (+) addition in summer season was higher compared to control and P added experiments. In the bay, silicon was not a major limiting factor for phytoplankton growth, whereas nitrogen (N) was considered as a limiting factor during spring and summer. Therefore, a sufficient silicate supply form water mixing Si recycled from diatom decomposition and river water is favorable form maintaining diatom ecosystems in Gwangyang Bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.129-139
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• 2002

We investigated the outbreak of red tides dominated by harmful dinoflagellates from August to November 1999 in the coastal waters off the southern Saemankeum areas where a huge red tide dominated by Cochlodinium polykrikoides had been first observed in 1998. We took water samples from 2~5 depths of 4 stations (with 3-4 additional stations during red tides) in this study period and then measured the abundance of phytoplankton, water temperature, salinity, and the concentrations of nutrients. In the study period harmful dinoflagellates Alexandrium tamarense, C. polykrikoides, Gymnodnium catenatum, Gyrodinium aureolum, Gymnodnium impudicum were present, and of these G. aureolum and C. polykrikoides formed red tide patches on September 16 and October 18, respectively. The date of the outbreak of red tide dominated by C. polykrikoides in the study area was approximately 50 days later than that off the Kohung areas in 1997 and the surface water temperature when the red tides outbroke in the former area was 6$^{\circ}C$ lower than that fur the latter area. The maximum abundance of C. polykrikoides on September 16, October 7 and 18 were 5, 14, and 463 cells $m\ell$$^{-1}$ , respectively. The growth rate of C. polykrikoides, isolated from the study area, was 0.3~0.4 d$^{-1}$ at 20~$25^{\circ}C$, which enable this species to reach the maximum concentration without being transported from the adjacent waters containing already made red tide patches. The outbreaks of red tides dominated by C. polykrikoides in the study area and off Kohung have occurred when and/or where the concentrations of diatoms were low. This evidence suggests that the outbreak of red tides dominated by C. polykrikoides is adversely affected by the high diatom concentrations or the conditions favorable for the growth of diatoms.

• Journal of Chest Surgery
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• v.38 no.2 s.247
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• pp.152-156
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• 2005

Background: Occlusive complications after arterial revascularization are difficult to treat and have high recurrence rate. This study was performed to establish an effective treatment modality and to evaluate the factors affecting the occlusive complications by analysis of clinical data. Material and Method: During the period of 5 years. 33 patients (55 reoperations) were studied at the Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital following 173 arterial revascularization surgeries. The clinical characteristics, operating methods, the time intervals of reoperation, used graft, and the results of treatment were evaluated retrospectively. Result: All the patients were men except one and the mean age was 63.5 years old. The mean time internal from first operation to reoperation was 11.9 months. The cause of arterial occlusive diseases were 28 atherosclerosis and 5 Burger's diseases, Associated diseases were Hypertension $(57.6\%)$, Diabetes mellitus $(33.3\%)$, heart failure $(18.2\%)$, and so on. The mean rate of reoperation was 1.67 times and the most common type of first operation was femoro-popliteal bypass grafting $(57.6\%)$. The graft that used revascularization surgery were 25 cases of PTFE and 6 case were Dacron. There was no statistical difference between two groups. The kinds of reoperations were thrombectomy in 20 cases, angioplasty 18 cases, re-bypass surgery in 13 cases, and lumbar sympathectomy in 4 cases. The results of reoperation were 15 cases of functional recovery, 7 cases of limb salvage, 5 cases of above-knee amputation. 3 cases of below-knee amputation and 3 deaths. Conclusion: The main cause of occlusive complications are occlusion of inflow or outflow artery. Treatments were different according to the first operation methods and graft used. The most frequent time of reoperation was within one year after the first operation. We believe that graft surveillance especially during the first year is very important factor in observing the patient. We can look forward to improving limb salvage rate to perform additional treatment such as radiological interventions and lumbar sympathectomy.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.639-650
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• 2022

Abeliophyllum distichum Nakai, a rare plant with distylous characteristics, is native to certain parts of the Korean Peninsula. It is registered on the IUCN Red List of Threatened Species as a globally endangered plant. This study was conducted to establish an appropriate local conservation management plan suitable for future A. distichum populations by comparing and analyzing the flowering characteristics and population size according to distyly based on the results of quantitative surveys in 14 regions, including 8 areas with native populations of A. distichum and 6 natural monument populations. The number of individuals appearing in each population group was surveyed, and the flowering individuals were identified by style as being either pin or thrum flower types as they were being examined and recorded on the site. In total, 13,130 individuals of A. distichum (7,003 flowering and 6,127 non-flowering individuals) were recorded, but the balance of the number of pin- and thrum-flowered individuals in each population was not significant (p<0.05), indicating an imbalanced state. In particular, the Yeongdong (YD) population was very disproportionate compared to other populations, suggesting that its genetic diversity was low and the possibility of inbreeding was high. The average flowering and fruiting rates by management unit were much higher in the natural monument populations (89.2% and 55.3%, respectively) than in the natural habitat populations (39.0% and 8.5%, respectively). It may be due to a difference in reproductive growth resulting from light inflow into the forest caused by the upper crown closure. The area of occupation (AOO) of A. distichum on the Korean Peninsula covered an area of 23,224.5 m². Although the natural monument population was smaller than the natural habitat population, its density was higher, likely as a result of the periodic management of natural monument populations, where the installation of protective facilities in certain areas restricts population spread. Conservation of A. distichum populations requires removing the natural monument populations suspected of anthropogenic and genetic disturbances and expanding the conservation priority population by designating new protected areas. Although the habitats of natural monument populations are managed by the Cultural Heritage Administration and local governments, there are no agencies that are responsible for managing natural habitat populations. Therefore, institutional improvement in the overall management of A. distichum should be prioritized.

• The Journal of Engineering Geology
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• v.29 no.1
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• pp.51-68
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• 2019

This study performs to evaluate adaptability of seashore filtering type seawater-intake which adapts dua1 filter well alternative for direct seawater-intake. This study varies filter condition of seashore free surface aquifer which is composed of sand layer then installs real size dual filter well and single filter well to evaluate water permeability and proper pumping amount according to filter condition. According to result of step aquifer test, it is analysed that 110.3% synergy effect of water permeability coefficient is happened compare to single filter since dual filter well has better improvement. dual filter has higher water permeability coefficient compare to same pumping amount, this means dual filter has more improved water permeability than single filter. According to analysis result of continuous aquifer test, it is evaluated that dual filter well (SD1200) has higher water permeability than single filter well (SS800) by analysis of water permeability coefficient using monitoring well and gauging well, it is also analysed dual filter has 110.7% synergy effect of water permeability coefficient. As a evaluation result of pumping amount according to analysis of water level dropping rate, it is analysed that dual filter well increased 122.8% pumping amount compare to single filter well when water level dropping is 2.0 m. As a result of calculating proper pumping amount using water level dropping rate, it is analysed that dual filter well shows 136.0% higher pumping amount compare to single filter well. It is evaluated that proper pumping amount has 122.8~160% improvement compare to single filter, pumping amount improvement rate is 139.6% compare to averaged single filter. In other words, about 40% water intake efficiency can be improved by just installation of dual filter compare to normal well. Proper pumping amount of dual filter well using inflection point is 2843.3 L/min and it is evaluated that daily seawater intake amount is about $4,100m^3/day$ (${\fallingdotseq}4094.3m^3/day$) in one hole of dual filter well. Since it is possible to intake plenty of water in one hole, higher adaptability is anticipated. In case of intaking seawater using dual filter well, no worries regarding damages on facilities caused by natural disaster such as severe weather or typhoon, improvement of pollution is anticipated due to seashore sand layer acts like filter. Therefore, It can be alternative of environmental issue for existing seawater intake technique, can save maintenance expenses related to installation fee or damages and has excellent adaptability in economic aspect. The result of this study will be utilized as a basic data of site demonstration test for adaptation of riverside filtered water of upcoming dual filter well and this study is also anticipated to present standard of well design and construction related to riverside filter and seashore filter technique.