• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.2
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• pp.76-90
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• 2018

To determine the distribution of mercury (Hg) in the coastal surface sediments around the Korean peninsula, the baseline concentration of Hg was estimated, the extent of contamination was assessed, and the factors controlling the distribution were discussed. The concentrations of Hg in surface sediments were significantly high in Jinhae-Masan Bay in the South Sea, Ulsan-Onsan Bay and Yeongil Bay in the East Sea, but Hg in other sediments showed a similar distribution to Cs and relatively very low concentration between 0.21 and $39.5{\mu}g/kg$ ($13.6{\pm}7.80{\mu}g/kg$). Compared to the sediment quality guidelines in Korea, 8 % of the surface sediments (n=282) analyzed in this study exceeded the values of the threshold effects level (TEL), and six sediments collected around Onsan Port were higher than the value of the probable effects level (PEL). The contamination levels of Hg were assessed by the enrichment factors using the baseline concentration (2.06Cs+1.75) based on the residual analysis from the linear regression line for Cs, and further, factors controlling the distribution of Hg were discussed by the comparison with geochemical substances depending upon the Hg enrichment level. Hg concentrations were correlated well with Cs concentration in the range of less than 1.69 of EF implying grain size control, while in the range of 1.69 and 4.03 Hg concentrations were correlated well with Fe oxyhyroxide and organic carbon contents, which indicates Hg was enriched by superior sorption capability. On the meanwhile, samples with higher EFs (4.03 to 74.9) showed fairly positive correlations with other metals (Cu, Zn, Pb) rather than geochemical substances. For samples in Youngil Bay and Ulsan-Onsan Bay (n=30), Hg concentrations were correlated only with other metals rather than geochemical substances implying simultaneous supply of metal particles from metal refineries. But samples at Gosung, Sokcho and Uljin coast were correlated well with organic carbon even though they had high EFs. In addition, samples in Jinhae-Masan Bay with high contents of S were enriched by relatively high sulfide formation.

• Clean Technology
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• v.27 no.4
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• pp.350-358
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• 2021

The results of this study shows that the combustor temperature ranged from 848.27 to 1,026.80 ℃, averaging about 976.61 ℃, and the NOx concentration increased as the temperature increased. The urea usage ranged from 291.00 to 693.00 kg d^-1, averaging about 542.34 kg d^-1, and the NOx concentration decreased as the urea usage increased. Residence time was about 3.38 to 9.17 s, averaging about 5.22 s, about 2.61 times larger than the 2 s of the design details. This is 1,086 kg h^-1, averaging about 55.71%, compared to the 1,950 kg h^-1 SRF input permission standard. The combustion chamber area is constant, but the residence time is shown to increase with the decrease of exhaust gas. The O₂/CO ratio was 847.05 to 14,877.34, averaging about 3,111.30, and the NOx concentration slightly increased as the O₂/CO ratio increased. As the combustor temperature and O₂/CO ratio increased, the combustion reaction with nitrogen in the air increased and the NOx concentration slightly increased. As the urea usage and residence time increased, the NOx concentration decreased slightly with an increase in reactivity with NOx. The NOx concentration at the stack ranged from 7.88 to 34.02 ppm with an average of 19.92 ppm, and was discharged within the 60 ppm emission limit value. The NOhx emission factor was 1.058 to 1.795 kg ton^-1, averaging about 1.450 kg ton^-1. This value was about 24.87% of the maximum emission factor of 5.830 kg ton^-1 of other solid fuels. Other synthetic resins and industrial wastes were 79.80% and 43.65% compared to 1.817 kg ton^-1 and 3.322 kg ton^-1, respectively. This value was similar to 1.400 kg ton^-1 of RDF in the NIER notice (2005-9), 10.98% compared to the maximum SRF of 13.210 kg ton^-1. Therefore, the NOx emission factor had a large deviation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.572-580
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• 2019

In view of the numerous discussions on global environmental issues, policies have been implemented to limit emissions in the field of marine transport, which accounts for a major part of international trade. In this study, a ship's emissions were calculated by applying the engine load factor to determine the total quantity of emissions based on the ship's speed reduction. For ships entering and leaving the Busan North Port from 1 January to 31 December 2017, emissions were calculated and analyzed based on the ship's type and its speed in the reduced speed zone (RSZ), which was set to 20 nautical miles. The comparison of the total amount of emissions under all situations, such as cruising, maneuvering, and hotelling modes revealed that the vessels that generated the most emissions were container ships at 76.1 %, general cargo ships at 7.2 %, and passenger ships at 6.8 %. In the cruising and maneuvering modes, general cargo ships discharged a lesser amount of emission in comparison with passenger ships; however, in the hotelling mode, the general cargo ships discharged a larger amount of emission than passenger ships. The total emissions of nitrogen oxides (NOx), sulphur oxides (SOx), particulate matter (PM), and volatile organic compounds (VOC), were 49.4 %, 45 %, 4 %, and 1.6 %, respectively. Furthermore, the amounts of emission were compared when ships navigated at their average service speed, 12, 10, and 8 knots in the RSZ, respectively. At 12 knots, the reduction in emissions was more than that of the ships navigating at their average service speed by 39 % in NOx, 40 % in VOC, 42 % in PM, and 38 % in Sox. At 10 knots, the emission reductions were 52 %, 54 %, 56 %, and 50 % in NOx, VOC, PM, and Sox, respectively. At 8 knots, the emission reductions were 62 %, 64 %, 67 %, and 59 % in NOx, VOC, PM, and Sox, respectively. As a result, the emissions were ef ectively reduced when there was a reduction in the ship's speed. Therefore, it is necessary to consider limiting the speed of ships entering and leaving the port to decrease the total quantity of emissions.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.2
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• pp.92-96
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• 2018

Purpose In case of nuclear medical hepatobiliary scan, To quantitatively evaluate contractility of a gallbladder, gallbladder ejection fraction (GBEF%) is calculated from anterior images using fatty meal. However, when a gallbladder and other organs overlap on an anterior image, the gallbladder ejection fraction is not accurately evaluated. In order to reduce this error, the objective of our study was to figure out whether there is a significant difference in GBEF% calculated from the anterior and right lateral images. Materials and Methods After intravenous injection of 99mTc-Mebrofenin 370 MBq to randomly 50 patients who visited our hospital, we started to examine nuclear hepatobiliary scan. Using skylight(Philips, United States), we acquired anterior and right lateral image at 10 minutes, 20 minutes, 30 minutes, 60 minutes, 90minutes after injection. Using images at 60 and 90 minutes, gallbladder ejection fraction (GBEF%) was calculated from the anterior and right lateral images using JETstream workspace. For drawing more accurate ROI, CT images were referenced and 4 radiologists calculated the GBEF% in the same image and calculated the average value. We assessed whether there was a significant difference in GBEF% calculated from the anterior and right lateral images using SPSS program(Statistical Package for the Social Science, SPSS Ver.18 Inc. USA). Results About randomly 50 patients, the average value of the GBEF% calculated from the anterior image was 63.212 and the average value of the GBEF% calculated from the right lateral image was 62.666. GBEF% decreased 0.433% on the right lateral image compared with anterior image. Result of paired sample t-test, p value is over 0.05. So, there was no significant difference in GBEF% calculated from the anterior and right lateral images. Conclusion In the case that a gallbladder and other organs are not separated on an anteior image, Right lateral image would be better to acquire more accurate GBEF% than using anterior image.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.275-285
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• 2021

COVID-19 is threatening the safety of ships and seafarers by delaying seafarer rotation. Shipping companies and governments have a blindspot in case of the onboard environment of seafarers. An effective, alternative plan should be devised to eliminate the possibility of human accidents in an emergency that threatens the safety of seafarers. According to the survey of former and current seafarers, the most important factor in boarding life was safety, and the most necessary thing during emergencies was to secure smooth seafarer rotation rather than improve wages and welfare. By analyzing the major routes of national shipping companies by continent, ports with a large number of calls and a high Air Connectivity Index were selected as the base port. In addition, the route was designed for effective, domestic seafarer rotation during international shipping. Other countries must be consulted to establish a travel route linking ships, ports, and airports for the safe return of sailors to their home countries during an emergency. In addition, it is necessary to work together for the seafarers who are in trouble of seafarer rotation through cooperation with the International Maritime Organization(IMO). Starting with this, the government should have a monitoring system for the return and non-return routes as well as the number of seafarers on board. If such a system is established, it will be able to determine the response direction of our country's policy in case of an emergency. Along with the shipping company's ef orts to improve the treatment of seafarers, national and social attention will be needed to review domestic laws and improve awareness about seafarers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1092-1099
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• 2022

Research on exhaust aftertreatment devices to reduce air pollutants and greenhouse gas emissions is being actively conducted. However, in the case of the particulate matters/nitrogen oxides (PM/NOx) simultaneous reduction device for ships, the problem of back pressure on the diesel engine and replacement of the filter carrier is occurring. In this study, for the optimal design of the integrated device that can simultaneously reduce PM/NOx, an appropriate standard was presented by studying the flow inside the device and change in back pressure through the inlet/outlet pressure. Ansys Fluent was used to apply porous media conditions to a diesel particulate filter (DPF) and selective catalytic reduction (SCR) by setting porosity to 30%, 40%, 50%, 60%, and 70%. In addition, the ef ect on back pressure was analyzed by applying the inlet velocity according to the engine load to 7.4 m/s, 10.3 m/s, 13.1 m/s, and 26.2 m/s as boundary conditions. As a result of a computational fluid dynamics analysis, the rate of change for back pressure by changing the inlet velocity was greater than when inlet temperature was changed, and the maximum rate of change was 27.4 mbar. This was evaluated as a suitable device for ships of 1800kW because the back pressure in all boundary conditions did not exceed the classification standard of 68mbar.

• Journal of Chest Surgery
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• v.41 no.3
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• pp.320-328
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• 2008

Background: Numerous surgical devices for mitral repair have been used in the past with good results. In this study we describe a simple annuloplasty technique with using a new device ($Mitracon^{(R)}$). The aim of this study was to assess its efficacy and surgical results with using $Mitracon^{(R)}$. Material and Method: From May 2003 to October 2005, 46 patients (21 women and 25 men (mean age of $51.4{\pm}17.8$ years) with mitral regurgitation from various causes were treated with either the $Mitracon^{(R)}$ (the $Mitracon^{(R)}$ group) or the Capentier Edward rigid ring (the CE group). The median follow-up duration was 18.9 months. Result: The mean grade of mitral regurgitation before and immediately after surgery in the $Mitracon^{(R)}$ group and the CE group decreased from $3.2{\pm}0.8$ to $0.6{\pm}0.7$ and $3.4{\pm}0.7$ to $0.3{\pm}0.5$, respectively. There were no significant changes in the ejection fraction either between the two groups or before and immediately after surgery. No deaths were seen in either group. Early postoperative echocardiography of all 46 patients showed only trivial mitral regurgitation or none at all. Echocardiography at a median of 18.9 months also showed no progression in mitral regurgitation. The mean grade of mitral regurgitation in the $Mitracon^{(R)}$ group at this time point decreased from $3.2{\pm}0.8$ to $0.8{\pm}0.7$ (p<0.05). The CE group also showed a similar degree of decrease from $3.4{\pm}0.7$ to $0.3{\pm}0.6$ (p<0.05). The mitral valve area in the $Mitracon^{(R)}$ group at 1 year follow-up was $3.3{\pm}0.9cm^2$. The mitral valve area in the CE group was $2.7{\pm}0.6cm^2$. The mean mitral pressure gradient in the $Mitracon^{(R)}$ group at 1 year follow-up was $3.1{\pm}1.3$ mmHg. The mean pressure gradient in the CE group was $4.5{\pm}2.1$ mmHg, although any statistical significant difference for this between the groups was not reached. Conclusion: The present study showed the described technique to be safe and effective in the intermediate term. Because long term results are unavailable, a more extensive prospective randomized multicenter trial may be warranted to determine whether this procedure should be generally applied for repair of mitral valve disease.

• Journal of Chest Surgery
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• v.35 no.9
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• pp.643-652
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• 2002

As the prevalence of coronay artery disease is increasing, the surgical treatment has been universalized and operative outcome has been improved. We analyzed the short and mid-term results of 292 CABGs performed in Kangdong Sacred Heart Hospital. Material and Method: From June 1994 to December 2001, 292 patients underwent coronary artery bypass grafting. There were 173 men and 119 women and their ages ranged from 39 to 84 years with a mean of $61.8{\pm}9.1$ years. We analyzed the preoperative risk factors, operative procedures and operative outcome. In addition, we analyzed the recurrence of symptoms, long-term mortality and complications via out-patient follow-up for discharged patients. Result: Preoperative clinical diagnoses were unstable angina in 137(46.9%), stable angina in 34(11.6%), acute myocardial infarction in 40(13.7%), non-Q myocardial infarction in 25(8.6%), postinfarction angina in 22(7.5%), cardiogenic shock in 30(10.3%) and PTCA failure in 4(1.4%) patients. Preoperative angiographic diagnoses were three-vessel disease in 157(53.8%), two-vessel disease in 35 (12.0%), one-vessel disease in 11(3.8%) and left main disease in 89(30.5%) patients. We used saphenous veins in 630, internal thoracic arteries in 257, radial arteries in 50, and right gastoepiploic arteries in 2 distal anastomoses. The mean number of distal anastomoses per patient was $3.2{\pm}1.0$ There were 18 concomitant procedures ; valve replacement in 8(2.7%), left main coronary artery angioplasty in 6(2.1%), patch closure of postinfarction ventricular septal defect(PMI-VSD) in 2(0.7%), replacement of ascending aorta in 1(0.3%) and coronary endarterectomy in 1(0.3%) patient. The mean ACC time was $96.6{\pm}35.3 $ minutes and the mean CPB time was $179.2{\pm}94.6$ minutes. Total early mortality was 8.6%, but it was 3.1% in elective operations. The most common cause of early mortality was low cardiac output syndrome in 6(2.1%) patients. The stastistically significant risk factors for early mortality were hypertension, old age($\geq$ 70 years), poor LV function(EF＜40%), congestive heart failure, preoperative intraaortic balloon pump, emergency operation and chronic renal failure. The most common complication was arrhythmia in 52(17.8%) patients. The mean follow-up period was $39.0{\pm}27.0$ months. Most patients were free of symptoms during follow-up. Fourteen patients(5.8 %) had recurrent symptoms and 7 patients(2.9%) died during follow-up period. Follow-up coronary angiography was performed in 13 patients with recurrent symptoms and they were managed by surgical and medical treatment according to the coronary angiographic result. Conclusion: The operative and late results of CABG in our hospital, was acceptable. However, There should be more refinement in operative technique and postoperative management to improve the results.