• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.63-76
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• 2006

For a private toll road project, deciding optimal toll is an important element of economic analysis for the project and a challengeable work. In this study, the optimal toll of a private toll bridge, Geoga Bridge which connects Geoje Island of Gyeongnam Province and Gaduk Island of Busan was estimated using Stated Preference (SP) data. The SP data were collected by interviewing the passenger car drivers travelling on the National Road 14. They are latent users of the bridge. A fuzzy approximate reasoning model to estimate the optimal toll was built using the SP data. For the input variable of the model, the saved travel time and toll level were employed and the diversion rate to the bridge was employed for the output variable. The diversion rates for each toll level and saved travel time were estimated and the toll level which had maximized the toll revenue was decided as optimal toll. The optimal toll was tested by comparing with the average pay rate of passenger car drivers. Since the optimal toll for passenger cars at one hour saving, the 6,250 won is about 50 % of the average pay rate of passenger car divers, the toll was evaluated not to be high. The technique employed in this study may be used for the estimation of the optimal tolls for other kinds of vehicles.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.1
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• pp.52-65
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• 2016

The electronic toll collection system(ETCS), is globally used in about 40 countries. In Korea, the Korea Expressway Corporation led the nationwide introduction of the ETC system in 2007 under the brand name of the Hi-pass. Since then, Hi-pass, with its rate of average daily use reaching about 70%, has become an essential facility in Korean expressways. To identify users' perception on Hi-pass (satisfaction, preference, etc.), this study conducted a Modified Importance-Performance Analysis (M-IPA). With this, this study attempted to identify the kind of efforts necessary to enhance current Hi-pass users' convenience and satisfaction. According to the result of M-IPA, the items including "non-stop payment" and "toll discount" are identified as key items that require further improvement. For improvement in the "non-stop payment" item, operations of Hi-pass toll booths appropriate for the demand for Hi-pass use and the selection of Hi-pass booths' locations in consideration of entry and exit lanes need to be improved. In addition, with regard to the "toll discount" item, although toll discount is currently provided to Hi-pass users, thus, PR thereof will have to be strengthened. It is expected that this study will be used as basic data to devise methods of enhancing Hi-pass usage through improvement of Hi-pass users' satisfaction.

• Journal of Chest Surgery
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• v.42 no.4
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• pp.456-463
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• 2009

Background: Although the reports on re-operative coronary revascularization (redo-CABG) have increased, there are only limited reports on redo-CABG using arterial grafts. The aim of this study was to analyze the safety and feasibility of using various arterial grafts for redo-CABG. Material and Method: A consecutive series of patients who underwent 33 redo-CABGs from March 2001 to July 2008 were retrospectively reviewed. We performed conventional CABG in 17 patients, on-pump beating CABG in 7, off-pump CABG in 7 and minimally invasive direct coronary artery bypass in 2. The grafted that were used included 34 internal thoracic arteries (ITA), 14 radial arteries, 14 right gastroepiploic arteries and others. Arterial composite grafts were constructed in 26 patients. Of these, a previously patent in-situ left ITA was re-used as the in-flow of a composite graft in 10 patients. Result: No hospital deaths or major wound problems occurred. The post-operative complications included 2 myocardial infarctions (6%), 1 intra-aortic balloon pump insertion (3%), 5 cases of atrial fibrillation (15.1 %) and 3 neurologic complications (9.1%). The meanfollow-up duration was 31.1$\pm$22.7 months and the 3 year survival rate was 86.4%. There were 4 late deaths (2 cardiac deaths) and no recurrent angina during the follow-up period. Conclusion: Redo-CABG with using various arterial grafts is currently a safe, feasible procedure, but further investigation and long term follow-up are needed.

• The Korean Journal of Ecology
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• v.24 no.3
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• pp.157-168
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• 2001

Herbicides have been used to control weeds for decades. If detoxification upon exposure to herbicides requires considerable amounts of energy, it could affect the pattern of resource allocation to growth and reproduction of crops. We examined the effects of three levels of a herbicide (Control, Low, and High) on germination, growth and reproductive characters of Glycine max treated twice, i.e., before and after seed germination. Since flowering time of G. max was separated into two groups, flowering time was also considered as a variable in this study. The rate of seed germination tended to be higher at the low level of herbicide compared to other levels. Chlorosis and shape variation of leaves were apparent after the second herbicide treatment, but completely disappeared after six weeks of treatment. The herbicide effects on growth characters were somewhat different between early and late flowering plants, but plants treated with both low and high levels of herbicide reduced their growth compared to those in the control group regardless of flowering time. Plants at the high level of herbicide exhibited the highest growth rate later in the season, suggesting that plants compensated to some extent for reduced growth. However, growth reduction among plants at the high level of herbicide was persistent until the end of growing season. Among plants flowered late in the season, plants in the control level bore a higher number of nodules per plant than those in other levels; such a pattern did not exist among plants flowered early in the season. Plants treated with low and high levels of herbicide produced a lower number of flowers than those in the control. Thus, the herbicide examined affected not only the growth and reproductive characters of non-target crops but also the development and growth of root nodules.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.613-622
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• 2009

The modal spilt of highway has been increased and the one of railway has been decreased from 17.2%(1990) to 6.3%(2006). In this context, it is meaningful to examine the competitiveness of the railroad of Korea. The objective of this study is to analyze the competitiveness of railroad with the highway so that countermeasures improving the competitiveness of railroad could be suggested. For this, firs of all, indicators representing the competitiveness of the railroad transport are determined. The main influencing factors for mode choice include transport time, transport cost and level of service. Three types of commodity, container, cement and steel are the target for the analysis. It was found that the overall competitiveness of railroad transport is weaker compared with highway even for the main freight origin-destination pairs. It means that the freight transport system is focused on road rather than railroad. Therefore, we need to remeasure the competitiveness of railroad transport related to methods for freight railroad competitiveness improvement.

• Journal of Chest Surgery
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• v.42 no.3
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• pp.331-336
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• 2009

Background: Open surgical repair of abdominal aortic aneurysms was initiated by Dubost in 1952. Despite the rapid expansion of percutaneous endovascular repair, open surgical repair is still recognized for curative intent. We retrospectively analyzed surgical outcome, complications, and mortality-related factors for patients with abdominal aortic aneurysms over a 6 year period. Material and Method: We analyzed 18 patients who underwent surgery for abdominal aortic aneurysms between March 2002 and March 2008. The indications for surgery were rupture, a maximal aortic diameter >60 mm, medically intractable hypertension, or pain. Result: The mean age was $66.6{\pm}9.3$ years (range, $49\sim81$ years). Twelve patients (66.7%) were males a 6 patients were females. Extension of the aneurysm superior to the renal artery existed in 6 patients (33.3%), and extension to the iliac artery existed in 13 patients (72.2%). Five patients (27.8%) had ruptured aortic aneurysms. The mean maximal diameter of the aorta was $72.2{\pm}12.9$ mm (range, $58\sim109$ mm). Surgery was performed by a midline laparotomy, and 6 patients underwent emergency surgery. The mean total ischemic time from aorta clamping to revascularization was $82{\pm}42$ minutes (range, $35\sim180$ minutes). The mortality rate was 16.7%; the mortality rate for patients with ruptured aneurysms was 60%, and the mortality rate for patients with unruptured aneurysms was 0%. The postoperative complications included one each of renal failure, femoral artery and vein occlusion, and wound infection. The patients who were discharged had a long-term survival of $34{\pm}26$ months (range, $4\sim90$ months). Rupture and emergency surgery had a statistically significant mortality-related factor (p < 0.05). Conclusion: Emergency surgery for ruptured aortic aneurysms continues to have a high mortality, but unruptured cases are repaired with relative safety. Successfully operated patients had long-term survival. Even though endovascular aortic repair is the trend for abdominal aortic aneurysms, aggressive application should be determined with care. Experience and systemic support of each center is important in the treatment plan.

• Journal of Ginseng Research
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• v.27 no.3
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• pp.103-109
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• 2003

We investigated the effect of ginseng total saponin (GTS) on the regeneration process of experimentally crush injured rat sciatic nerves. The bilateral sciatic nerves of fifty adult male Sprague-Dawley rats were compressed surgically with a straight hemostat for 30 seconds with 1 mm width. Twenty rats were divided into four groups to test the dose-dependent effect of GTS (0, 50, 100, or 150 mg/kg, i.p.). Saline for vehicle control group or GTS dissolved in saline was administerd for three weeks. After that period of time, the numbers of total myelinated axon and degenerated myelin in the sciatic nerves of bilateral legs were examined and analyzed using image analysis system to confirm a morphological effect of GTS. We found that the most effective concentration of GTS for the regeneration of damaged sciatic nerve was 150 mg/kg. In another set of experiment, thirty rats were divided into two groups as saline-treated vehicle group and GTS-treated group (150 mg/kg, i.p.) for three weeks. Every week we examined the numbers of total myelinated axon and degenerated myelin in the sciatic nerves of bilateral legs using image analysis system to evaluate the effect of GTS on injured nerves. We found that the regeneration of damaged sciatic nerves was facilitated in GTS-treated group compared to saline-treated group until two weeks. However, after that period of time we could not observe the significant difference between saline-treated group and GTS-treated group. These results suggest that GTS is a useful adjuvant therapy for the regeneration of the peripheral nerve injury in short period of treatment.

• Journal of Chest Surgery
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• v.36 no.3
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• pp.142-149
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• 2003

To know the feasibility of the coronary artery bypass graft (CABG) for multivessel coronary artery disease with purely bilateral internal thoracic arteries (ITAs), we analyzed the short-term clinical results and the coronary angiography of the patients. Material and Method: From March 2001 to June 2002, four hundred and five patients underwent CABG. Purely bilateral ITAs were used in 159 patients (39.3%). We analyzed these patients retrospectively The mean age of these patients was $61.2{\pm}8.5$ (range: 30 ~80) years and there were 123 male patients. The preoperative risk factors were as follows: diabetes in 54 patients (34.0%), history of acute myocardiac infarction within 4 weeks in 29 (18.2%), and emergency operation in 6 (3.8%). Off-pump CABG was carried out in 128 patients (80.5%). Associated procedures were mitral valvuloplasty (5), aortic valve replacement (3), Dor procedure (1), and so on. Result: The mean number of distal anastomoses was $3.1{\pm}0.9$ (range: 2~6), the mean duration of hospital stay was $8.4{\pm}4.5$ days. There was one (0.6%) operative death. Except for one early death, no other patients suffered from low cardiac output. The other postoperative complications were occurred as follows: reoperation due to bleeding in 3 patients, perioperative myocardiac infarction in 1, transient cardiac arrest in 2, transient cognitive dysfunction in 7, and transient ischemic attack in 1, and deep sternal wound infection in 1 patient. Recently, early postoperative angiography was performed in 19 patients who had triple vessel disease. The total number of distal anastomosis was 78 (mean $4.1{\pm}0.8$/patient). All distal anastomosis sites were patent, but competition flow was observed at the bypass sites where the native coronary artery stenosis was not significant. Conclusion: The CABG with purely bilateral ITAs for triple vessel disease was performed safely. The early patency rate was relatively good in small number of patients. However the long-term patency rate and the functional study to evaluate the sites where competition flow was observed should be followed.

• Journal of Chest Surgery
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• v.36 no.10
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• pp.728-733
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• 2003

Background: The aim of the current study was to assess the effects of total arterial myocardial revascularization (TAMR) with bilateral internal mammary arteries. Material and Method: 139 consecutive patients who underwent off pump coronary artery bypass surgery from January 2000 to December 2001 were included in the current retrospective study. Patients were divided into those receiving bilateral internal mammary artery, BITA (n=85) and those receiving single internal mammary artery, SITA (n=54). Result: There was only one death in each group. No significant differences were noted in the total ICU and hospital stay; 2.4$\pm$1.7 and 11.2$\pm$17.7 days, in the BITA group, respectively and 2.8$\pm$2.7 and 9.7$\pm$7.1 days in the SITA group, respectively (P>0.05). The mean number of distal anastomosis of 3.9$\pm$0.7 was slightly higher in the SITA group compared to the SITA group, which was 3.1$\pm$0.8. Myocardial infarction occurred in 7 patients (BITA group: 2, SITA group: 5) and deep sternal infection necessitating reoperation occurred in 4 patients (BITA group: 3, SITA group: 1). Coronary angiogram was performed in the immediate postoperative period in 104 patients (BITA group: 64/85, SITA group: 40/54). Of these patients, stenosis in the LAD anastomosis site occurred in 4 patients (BITA group: 2, SITA group: 2). A total of 8 anastomotic sites were stenotic in the entire series of which percutaneous intervention was performed in 3 patients and none required reoperative coronary artery bypass. Conclusion: The results of the current data did not show a significant difference in patiency rate with bilateral internal mammary artery use for CABG supporting the feasibility of its use as a viable alternative method for TAMR.

• Journal of Chest Surgery
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• v.37 no.10
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• pp.827-832
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• 2004

Background: The significance of MIDCAB is emerging topics recently as OPCAB is going to be universalized, and long-term outcome of bypass graft surgery was proved to be more excellent than balloon dilation or stent insertion. We report our MIDCAB results in 73 patients in the last three years. Material and Method: Retrospective analysis of medical records was done from November 1, 2000 through November 31, 2003. There were 47 males and 26 females ranging in age from 31 years to 79 years (average $61.3\pm9.8$ years). Observation periods after operative procedures were 10 to 1238 days (average $763\pm319.8$ days). Left longitudinal parasternal incision as a standard procedure was done to approach the heart after dissection of the left internal thoracic artery by partial or total resection of 3rd to 5th ribs. Result: Of those patients, 46 patients were transferred to ICU after extubation at operation room and 58 patients were extubated within 3 hours after operation. Average ICU staying periods was $26.8\pm11.5$ hours. Follow-up angiography during admission was done in 36 patients and showed 100% patency. Only one patient died on the 10$^{th}$ post operative day because of sudden CVA. Complications included wound problems in 4 patients, and constructing pericardial window using thoracoscopy due to continuous pericardial effusion in 1. Permanent pacemaker was inserted in one patient owing to sick sinus syndrome. In one patient with recurrence of angina 8 months after operation, stenosis at anastomic site was found and improved with balloon dilatation. Conclusion: We were satisfied with our results of MIDCAB in single and multi-vessel coronary artery disease. These results have made the cardiologists tried to operate positively and we expect widening operative indications including hybrid revascularization.