• Economic and Environmental Geology
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• v.34 no.3
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• pp.271-281
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• 2001

The characteristics of the heavy metal contamination in the soils affected by the tailings of the Palbong mine have been studied. The soils in the studied area consist mostly of loam by the particle size analysis, but a little of it, located near the stream, consist of loamy sand to sandy loam, finally to loam downward. The organic contents of soils are significantly low aoom 2 percent and the pH is in acidic ranging 6.0 $\pm$ 0.1. The samples of the parent rocks, the normal soils, the tailings and the channel deposits from the studied area were chemically analysed. From the result, the heavy metal concenlration of the soils is a little Jow compared with that of the parent rocks, shows the hydrologic process of the surface and the groundwater. The contamination of the tailings from the ore mining are high in lead, copper and arsenic. In the channel deposits the concenlrations of lead and copper are abnormally high but that of arsenic is uniquely low. And most of heavy metal contamination are decreased with the distance from the mine. It is caused by the properties of the surface and the ground water during the process of the heavy metal migration. The correlation-coefficient between sand and silt contents and the concentrations of Cd, Cu and Pb are significant but the amounts of As and Hg are increased with the clay contents. The dispersion of the heavy metals with the distance shows that the concentrations of them in the soils sampled at distance of 100 m to 200 m along the stream started near the Palbong mine are extremely high compared with those from other distances. These discrepancies are significant in Cd, Cu, Pb and Hg, but low in As. All the samples contain below detection limit of Cr+6 In the present stream water the concentrations of the heavy metals are not detected. So, it is interpreted that the concentrations in the soils are caused by the activities of the mining during the operation and have been continued by the dispersion from the tailings since after the closure of the mining, especially by the surface and ground water. The concentrations are diminished with the distance from the mining site, but in the interval of 800-2000 m increases abruptly. In the soil samples counted on the dispersion direction by wind, the lowering of the concentration is relatively uniform with the distance from the mining site. So, the rapid increase of the heavy metal concentrations is presumed to have been caused by the ground-water movement. In the migration of the heavy metals, the groundwater conditions, such as pH, Eh, the contents of colloidal particles, and Mn and Fe oxides are closely involveo. Integrating with these factors, it is interpreted that the groundwater conditions which have caused the heavy metal contamination of the studied area are those that the pH is about 3 in oxidized conditions, the contents of the colloidal particles are low, and Mn and Fe oxides are not involved in the migration of the heavy metals. Meanwhile, the vegetables growing on the soils in the studied area are not affected by the contamination of the heavy metals.

• Korean Journal of Ecology and Environment
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• v.44 no.3
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• pp.264-271
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• 2011

At the Jangheung multipurpose dam, which is on the Tamjin River, a trapping and trucking operation was established to maintain continuous upstream migration of fish,. To facilitate fish gathering, installation of an effective fishing trap was required. In this study, we evaluated the fish trap, established at the Jangheung dam, using PIT (Passive Integrated Transponder) telemetry. A total of 254 individuals from 15 species were monitored. Among these tagged species, 36 individuals from 6 species (Carassius auratus, C. cuvieri, Zacco temminckii, Z. platypus, Pungtungia herzi, and Pseudobagrus koreanus) were detected; a 14.2% detection rate. C. auratus recorded the highest detection rate of 44.2% while P. herzi was 14.3%. Z. temminckii and Z. platypus showed relatively low detection, 5% and 7.7% respectively. Some of individuals from C. auratus and Z. platypus did not pass through the antenna at the first attempt but were continuously detected on multiple days. There were no statistical differences in body size (total length, standard length and body weight) of individuals that did or did not swim into the trap (Mann-Whitney U test, p>0.05). Fish mainly swam into the trap during outflow of water from the dam (Mann-Whitney U test, p<0.001) and showed a higher detection frequency in daytime than nighttime (Mann-Whitney U test, p<0.001). Thus, for fish movement into the trap, external factors such as outflow from dam and time of day have important roles. Based on detection rate, not all fishes showed upstream migration but represented selective migration. Consequently, the establishment of flexible outflow strategies that take into consideration ecological characteristics of fishes should required for improving the efficiency of fishway.

• Journal of Chest Surgery
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• v.35 no.1
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• pp.27-35
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• 2002

Background: A perioperative myocardial infarction(PMI) is one of the major complications after CABG. Among diagnostic methods of PMI, CK-MB activity assays have been increasingly replaced by CK-MB mass assays, which have more sensitive, simple measurement. Also, new cardiac-specific and -sensitive marker, cardiac troponin I(cTnl), has been shown to be a marker of myocardial infarction. We report our evaluation of clinical significance of CK-MB mass and cTnl as a marker of PMI after CABG. Material and Method: We studied 32 patients who underwent CABG at Kangdong Sacred Hospital between April 2000 and April 2001. Postoperative serum CK-MB activity level, serum CK-MB mass, cTnl, electrocardiogram, echocardiogram, and clinical data were recorded prospectively The diagnosis of PMI was defined as positive 2 among 3 or all of the following , by a new Q wave on the electrocardiogram, by serum CK-MB activity higher than 200 lU/L within 72 hours after operation, and by new regional wall motion abnormality on the echocardiogram. Result: After CABG, 3 patients had sustained a PMI according to current diagnostic criteria. As serum CK-MB activity time course, a level of CK-MB activity 12 hours after CABG had very linear correlated significance with serum CK-MB mass 24hours(R=0.946) and cTnl 48 hours(R=0.933) after CABG(p=0.000). As we used a receiver operating characteristics curve(ROC curve) for a diagnostic cutoff value in patients with PMI, serum CK-MB mass levels higher than 30.05 ug/L 24 hours after CABG detected the presence of PMI with an area under the ROC curve of 1.0, a sensitivity of 100%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 100%. Also serum cTnl levels higher than 17.15 ug/L 48 hours after CABG detected the presence of PMI with an area under the ROC curve of 0.98, a sensitivity of 100%, a specificity of 96.6%, a positive preclictive value of 75%, and a negative predictive value of 100% Conclusion: We concluded that both the measurement of CK-MB mass and cTnl are the easier, accurate methods as a diagnostic marker of PMT after CABG, also as a proposal of diagnostic cutoff value enables to an early detection of PMI. However, a 1arger number of patient will be needed because of statistic limitation that a small number of participating patients, a small number of PMI.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.97-104
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• 2016

In Korea, the number of crash accident victims per 100,000 population is three times higher than the average of OECD. In particular, 60% of it occurs on the community road. Thus, this study intends to analyze the causes of such accidents through a pedestrian and vehicle traffic survey. The purpose is to establish practical safety enhancement measures for community roads. In recent years, lots of changes have occurred in the pedestrian environment. A traffic survey shows that 65% of pedestrians walk on the right and 17% of people use smart-phones while walking. An eye camera experiment shows that the operation load of drivers on the community roads is more than 4 times higher than those in urban roads. According to a speed survey, 62% of vehicles drive at 30km/h or above. The characteristics of accidents on community roads are as follows. First, the ratio of accidents on the edge of the road is 2.3 times as high as those on other roads. Second, when people walk on the right, the ratio of accidents is 2.5 times as high as that of walking on the left. Third, it becomes more dangerous when people cross the road from the right to the left. The majority of accidents is caused by unsafe driving (84.4%). When a vehicle makes a left turn, the likelihood of accidents is 2.3 times as high as those caused by a right turn. The ratio of accidents caused by vehicles going backwards is 14% among all accidents. In community roads, the focus of drivers should be at least 4 times higher than those on urban roads. Thus, walking in the opposite direction of vehicles and careless behaviors are highly likely lead to accidents.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.322-331
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• 2016

Oil budget calculator identifies the removal pathways of spilled oil by both natural and response methods, and estimates the remaining oil required response activities. A oil budget calculator was newly developed as a response tool for Deepwater Horizon oil spill incident in Gulf of Mexico in 2010 to inform clean up decisions for Incident Comment System, which was also successfully utilized to media and general public promotion of oil spill response activities. This study analyzed the theoretical background of the oil budget calculator and explored its future application to Korea. The oil budge calculation of four catastrophic marine pollution incidents indicates that 3~8% of spilled oil was removed mechanically by skimmers, 1~5% by in-situ burning, 4.8~16% by chemical dispersion due to dispersant operation, and 37~56% by weathering processes such as evaporation, dissolution, and natural dispersion. The results show that in-situ burning and chemical dispersion effectively remove spilled oil more than the mechanical removal by skimming, and natural weathering processes are also very effective to remove spilled oil. To apply the oil budget calculator in Korea, its parameters need to be optimized in response to the seasonal characteristics of marine environment, the characteristics of spilled oil and response technologies. A new algorithm also needs to be developed to estimate the oil budget due to shoreline cleanup activities. An oil budget calculator optimized in Korea can play a critical role in informing decisions for oil spill response activities and communicating spill prevention and response activities with the media and general public.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.467-474
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• 2014

Preliminary design in chemical process furnishes economic feasibility through calculation of both mass balance and energy balance and makes it possible to produce a desired product under the given conditions. Through this design stage, the process possesses unchangeable characteristics, since the materials, reactions, unit configuration, and operating conditions were determined. Unique characteristics could be very economic, but it also implies various potential risk factors as well. Therefore, it becomes extremely important to design process considering both economics and safety by integrating process simulation and quantitative risk analysis during preliminary design stage. The target of this study is LNG liquefaction process. By the simulation using Aspen HYSYS and quantitative risk analysis, the design variables of the process were determined in the way to minimize the inherent explosion risks and operating cost. Instead of the optimization tool of Aspen HYSYS, the optimization was performed by using stochastic optimization algorithm (Covariance Matrix Adaptation-Evolution Strategy, CMA-ES) which was implemented through automation between Aspen HYSYS and Matlab. The research obtained that the important variable to enhance inherent safety was the operation pressure of mixed refrigerant. The inherent risk was able to be reduced about 4~18% by increasing the operating cost about 0.5~10%. As the operating cost increases, the absolute value of risk was decreased as expected, but cost-effectiveness of risk reduction had decreased. Integration of process simulation and quantitative risk analysis made it possible to design inherently safe process, and it is expected to be useful in designing the less risky process since risk factors in the process can be numerically monitored during preliminary process design stage.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.31-38
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• 2020

The characteristics of ship traffic routes and the long term fluctuation in marine traf ic volume of the incoming and outgoing routes of the Yeosu Gwangyang Port were analyzed using vessel traffic data from the past 22 years and a real-time vessel traffic volume survey performed for 72 hours per year, for three years, between 2015 and 2017. As of 2017, the number of vessels passing through Yeosu Gwangyang Port was about 66,000 and the total tonnage of these ships was about 804,564 thousand tons, which is a 400 % increase from the 189,906 thousand tons shipped in 1996. Specifically, the dangerous cargo volume was 140,000 thousand tons, which is a 250 % increase compared to 1996. According to the real-time vessel traffic volume survey, the average daily number of vessels was 357, and traf ic route utilization rates were 28.1 % in the Nakpo sea area, 43.8 % in the specified sea area, and the coastal area traf ic route, Dolsan coastal area, and Kumhodo sea area showed the same rate of 6.8 %. Many routes meet in the Nakpo sea area and, parallel and cross passing were frequent. Many small work vessels entered the specific sea area from the neighboring coastal area traffic route and frequently intersected the path of larger vessels. The anchorage waiting rate for cargo ships was about 24 %, and the nightly passing rate for dangerous cargo ships such as chemical vessels and tankers was about 20 %. Although the vessel traffic volume of Yeosu Gwangyang Port increases every year, the vessel traffic routes remain the same. Therefore, the risk of accidents is constantly increasing. The route conditions must be improved by dredging and expanding the available routes to reduce the high risk of ship accidents due to overlapping routes, by removing reefs, and by reinforcing navigational aids. In addition, the entry and exit time for dangerous cargo ships at high-risk ports must be strictly regulated. Advancements in the VTS system can help to actively manage the traffic of small vessels using the coastal area traffic route.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.419-425
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• 2017

In this study, the performance characteristics of the K-based sorbents (KEP-CO2P2, KEPCO RI, Korea) has been studied in relation with the heat exchanger structure and shape in a mixing zone of the carbonator in the bench-scale dry $CO_2$ capture process. Two types of heat exchangers (different structure and shape) were used in the carbonator as CASE 1 and CASE 2, in which the experiment has been continuously performed under the same operating conditions. During the continuous operation, working temperature of carbonator was 75 to $80^{\circ}C$, that of regenerator was 190 to $200^{\circ}C$, and $CO_2$ inlet concentration of the feed gas was 12 to 14 vol%. Especially, to compare the dynamic sorption capacity of sorbents, the differential pressure of the mixing zone in the carbonator was maintained around 400 to 500 mm $H_2O$. Also, solid samples from the carbonator and the regenerator were collected and weight variation of those samples was evaluated by TGA. The $CO_2$ removal efficiency and the dynamic sorption capacity were 64.3% and 2.40 wt%, respectively for CASE 1 while they were 81.0% and 4.66 wt%, respectively for CASE 2. Also, the dynamic sorption capacity of the sorbent in CASE 1 and CASE 2 was 2.51 wt% and 4.89 wt%, respectively, based on the weight loss of the TGA measurement results. Therefore, It was concluded that there could be a difference in the performance characteristics of the same sorbents according to the structure and type of heat exchanger inserted in the carbonator under the same operating conditions.

• Progress in Medical Physics
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• v.15 no.1
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• pp.1-8
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• 2004

Patient dose verification is one of the most Important responsibilities of the physician in the treatment delivery of radiation therapy. For the task, it is necessary to use an accurate dosimeter that can verify the patient dose profile, and it is also necessary to determine the physical characteristics of beams used in intensity modulated radiation therapy (IMRT) The Beam Intensity Scanner (BInS) System is presented for the dosimetric verification of the two dimensional photon beam. The BInS has a scintillator, made of phosphor Terbium-doped Gadolinium Oxysulphide (Gd$_2$O$_2$S:Tb), to produce fluorescence from the irradiation of photon and electron beams. These fluoroscopic signals are collected and digitized by a digital video camera (DVC) and then processed by custom made software to express the relative dose profile in a 3 dimensional (3D) plot. As an application of the BInS, measurements related to IWRT are made and presented in this work. Using a static multileaf collimator (SMLC) technique, the intensity modulated beam (IMB) is delivered via a sequence of static portals made by controlled leaves. Thus, when static subfields are generated by a sequence of abutting portals, the penumbras and scattered photons of the delivered beams overlap in abutting field regions and this results in the creation of “hot spots”. Using the BInS, inter-step “hot spots” inherent in SMLC are measured and an empirical method to remove them is proposed. Another major MLC technique in IMRT, the dynamic multileaf collimator (DMLC) technique, has different characteristics from SMLC due to a different leaf operation mechanism during the irradiation of photon and electron beams. By using the BInS, the actual delivered doses by SMLC and DMLC techniques are measured and compared. Even if the planned dose to a target volume is equal in our experimental setting, the actual delivered dose by DMLC technique is measured to be larger by 14.8% than that by SMLC, and this is due to scattered photons and contaminant electrons at d$_{max}$.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.870-874
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• 2006

Purpose : Popular use of fetal ultrasonography has increased to detect congenital hydronephrosis(CH) which is the most common anomaly prenatally detected. We'd like to determine the frequency and clinical characteristics of prenatally diagnosed CH and outcome of ureteropelvic junction stenosis(UPJS). Methods : The records of births between January 1994 and June 2003 in Chonnam National University Hospital(CNUH), and the records of children who were diagnosed with CH in the Department of Pediatrics of CNUH during the above period, were retrospectively analyzed. In the patients with UPJS, the initial anterior posterior diameters of renal pelvis(APD) were compared between the spontaneous regression (SR) and operation group(OP). In the SR group, sequential regression rates of APD were estimated. Results : Among a total 9,076 births, 231(2.54 percent) patients with 293 renal units were diagnosed as CH and 19(6.78 percent) renal units spontaneously regressed 3 days after birth. In 228 children(56 bilateral; 172 unilateral; total 284 renal units) diagnosed with CH in the department of pediatrics of CNUH, male(71.9 percent) and left kidney(69.2 percent) predilection were found and 78.1 percent of CH were caused by UPJS. The initial APD of the SR group(121 units) in UPJS was $7.8{\pm}6.28mm$, which was significantly smaller than the APD($26.8{\pm}12.14mm$) of the OP group(25 unit)(P<0.05). In the SR group, 81 percent spontaneously regressed within one year. Conclusions : In CH, male and left kidney predilection were found. UPJS was the most common cause of CH and initial APD in UPJS at 3 days of age was a good prognostic indicator. Close monitoring should be done for at least one year because most SR in UPJS regressed spontaneously within one year.