• Journal of Chest Surgery
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• v.36 no.4
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• pp.242-254
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• 2003

Most of the studies conducted have investigated the beneficial effects of ischemic preconditioning on normothermic myocardial ischemia. However, the effect of preconditioning could be attenuated through the use of multidose cold cardioplegia as practiced in contemporary clinical heart surgical procedures. The purpose of this study was to investigate whether preconditioning improves postischemic cardiac function in a model of 25℃ moderate hypothermic ischemic heart induced by cold cardioplegia in isolated rat hearts. Material and Method: The isolated Sprague-Dawley rat hearts were randomly assigned to four groups. All hearts were perfused at 37℃ for 20 minutes with Krebs-Henseleit solution before the baseline hemodynamic data were obtained. Group 1 consisted of preconditioned hearts that received 3 minutes of global ischemic preconditioning at 37℃, followed by 5 minutes of reperfusion before 120 minutes of cardioplegic arrest (n=6). Cold (4℃) St. Thomas Hospital cardioplegia solution was infused to induce cardioplegic arrest. Maintaining the heart at 25℃, infusion of the cardioplegia solution was repeated every 20 minutes throughout the 120 minutes of ischemic period. Group 2 consisted of control hearts that underwent no manipulations between the periods of equilibrium and 120 minutes of cardioplegic arrest (n=6). After 2 hours of cardioplegic arrest, Krebs solution was infused and hemodynamic data were obtained for 30 minutes (group 1, 2: cold cardioplegia group). Group 3 received two episodes of ischemic preconditioning before 30 min of 37℃ normothermic ischemia and 30 minutes of reperfusion (n=6). Group 4 served as ischemic controls for group 3 (group 3, 4: warm ischemia group). Result: Preconditioning did not influence parameters such as left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), rate-pressure product (RPP) and left ventricular dp/dt (LV dp/dt) in the cold cardioplegia group. (p=NS) However, preconditioning before warm ischemia attenuated the ischemia induced cardiac dysfunction, improving the LVSP, LVEDP, RPP, and LVdp/dt. Less leakage of CPK and LDH were observed in the ischemic preconditioning group compared to the control group (p<0.05). Conclusion: Ischemic preconditioning improved postischemic cardiac function after warm ischemia, but did not protect cold cardioplegic hearts.

• The Korean Journal of Nuclear Medicine
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• v.26 no.2
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• pp.299-306
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• 1992

Gastic emptying scan in diabetic patients is widely used to assess the degree of motility disturbance and the symtoms such as nausea, vomiting, bloating, abdominal pain and early gastric fullness which we can't find anatomic lesion by fiberoscopic or barium study In order to determine the relationship among diabetic gastropathy, neropathy, retinopathy and disease duration, gastric emptying scan using $^{99m}Tc-tin$ colloid labeled scramble egg in hamburger was performed in 10 healty male controls and 50 diabetic patients which were subdivided to no neuropathy, peripheral neuropathy and autonomic neuropathy groups according to the degree of diabetic neuropathy and no retinopathy, background retinopathy and proliferative retinopathy groups according to the degree of diabetic retinopathy. After medication of cisapride for 2 weeks, we observed the presence of improvement of gastric motility in diabetics. The results were as following: 1) In controls, gastric emptying time (GET1/2) was $75{\pm}13.6$ min and 2 hour gastric retension rate (GRR2) was $32{\pm}11.1%$. 2) In diabetics, GET/2 was prolonged more than 2 hours and GRR2 was $58{\pm}23.1%$. According to degree of neuropathy, GET1/2 was prolonged more than 2 hours in all three groups and GRR2 was $54{\pm}24.1%$ in no neuropathy group, $57{\pm}24.3%$ in peripheral neuropathy group and $69{\pm}24.6%$ in autonomic neuropathy group. According to degree of retinopathy, GET1/2 was $110{\pm}23.4$ min in no retinopathy group and prolonged more than 2 hours in other two groups and GRR2 was $45{\pm}21.6%$ in no retinopathy group, $71{\pm}19.7%$ in background retinopathy group and $73{\pm}21.5%$ in proliferative retinopathy group. 3) After cisapride medication for 2 weeks, GET1/2 and GRR2 were improved as $90{\pm}14.6$ min and $40{\pm}13.8%$ (initial GET1/2 and GRR2 were above 2 hours and $61{\pm}15.4%$). We can conclude from above findings that gastropathy in diabetic neuropathy suggesting main underlying factor in motility disorder The degree of retinopathy and disease duration were correlated with severity of gastropathy in diabetics. From the results of gastric emptying scan, we can conclude that cisapride was useful drug for improving diabetic gastropathy and gastric emptying scan was valuable for assessing severity of diabetic gastropathy as non-invasive method.

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.282-287
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• 2004

Purpose: Since preoperative staging in esophageal cancer is important in both therapy and prognosis, there had been many efforts to improve its accuracy. Recent studies indicate that whole body FDG-PET has high sensitivity in detection of metastasis in esophageal cancer. Therefore, we added FDG-PET to other conventional methods in staging esophageal cancer to evaluate the usefulness of this method. Materials & Methods: Subjects were 142 esophageal cancer patients (average $62.3{\pm}8.3$ yrs) who received CT and PET just before operation. First, we compared N stage and M stage of the CT or PET with those of the post-operative results. Then we compared the stage according to the EUS (T stage) and CT (N and M stage) or SUS (T stage) and CT & PET (N and M stage) to that according to the post-operative results. Results: Among 142 patients, surgical staging of 69 were N0 and 73 were N1. In M staging, 128 were M0 and 14 were M1. Sensitivity, specificity, and accuracy of N staging were 35.6%, 89.9%, 62.0% with CT and 58.9%, 71.0%, 64.7% with PET, respectively. In M staging, 14.3%, 96.9%, 88.7% with CT and 50.0%, 94.5%, 90.1%, with PET, respectively. The concordances of [EUS+CT] and [EUS+CT+PET] with post-operative results were 41.2% and 54.6%, respectively and there was significant improvement of staging with additional PET scan (p<0.005). Conclusion: The concordance of [EUS+CT+PET] with post-operative result was significantly increased compared to that of [EUS+CT]. Thus, the addition of FDG-PET with other conventional methods may enable more accurate preoperative staging.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.91-98
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• 2008

Purpose: Radio-isotopes (RI) use has been steadily developing due to industrial and technical development in the modern medical society. Particularly, popularization of domestic cyclotrons dramatically enable hospitals to produce and use diagnostic radio-isotopes. Generally, only specific facilities such as hospitals, research institutes, nuclear power plants and universities can use radio-isotopes, they are also responsible for ventilation system. The strength of radioactivity in the air is strongly regulated and controlled by korea atomic energy law in Korea Institue of Nuclear Safety (KINS), so that air radioactivity exposure can lead to environmental pollution surrounding places. In this study, we'd like to find out the investigation and the present condition of the controlled ventilation system in domestic hospitals by an emission standard from KINS, and try to reach an agreement about how to use the ventilation system. Result: Definition of filters, features and structures of pre-filters, hepa-filters, charcol filters, filter exchange procedures and precautions are explained. RI deflation concentration and filter exchange cycle have been presented as a standard prescribed in the rules of KINS. The Radiation Control Management System (RCMS) introduced by Seoul National University Bundang Hospital linking to digital pressure gauge with computer controller in another medical facilities were described in details. Conclusions: The system of medical facilities using RI has been remarkably developing in 21 century. Especially, radiation safety control system has also been grown rapidly into the subdivision, specialization, advanced technology along with international technical improvement. However, As far as current RI ventilation system is concerned, it has nothing better than doing in the past. Preferentially, to reinforce this, more sophisticated system with strict periodic filter exchange and exhaust air control guidance should be introduced by applying brilliant domestic information technology for RCMS and digital gauge method. From personal point of view as a radiation safety manager, I have provide with present problems and improvements. Futhermore, more improved guidance should be conducted.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1598-1603
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• 1969

A field expeperiment has been conducted in order to explore possibilities of efficient and economical irrigation methods for the rice cultivation through which irrigation water may be saved and rice paddies may keep water for longer period of time, resulting in an increased yield of rice. Some of the major findings from the experimentation are summarized in the following. 1. There is slightly significant difference among experimental plots in the weight of rice straw. 2. The 9cm-lined plot proves to be the best in terms of the thickness. In this connection, however, it seems to by 3cm. 3. The wheat straw-lined plot is found superior in yield. However, this may be resulted in by the application of more fertilizer, and how long the plot could be durable may be problematic. Since every two or three years the straw-lining work has to be done, more labour may be required of the plot. 4. It would be inappropriate to expect any meaningful experimental results for the first year, since surface soil and deep soil are mixed up in the course of work. There is not observed any meaningful difference in the number of ears per stalk and in the number of grains per ear. However, in the lined plots, the number of tillers is slightly increased. 5. Irrigation has been applied by means of ordinary method after lining. When irrigation is applied at the interval of five to six days, irrigation water is saved by 44.9 per cent in the case of 9cm-lined plot, 39.7 per cent in the case of 6 cm-lined plot, and 36.3 percent in the case of 3 cm-lined plot. 6. An increased yields arenoted in the wheat straw-lined plot by 23.8 per cent, in the 9 cm-lined plot by 20.1 per cent, in the 3 cm-lined plot by 12 per cent. and in the case of vinyl-lined plot by 12.5 per cent. 7. The rate of maturity of grains is proved better, and the husking rate also found better(75%), that is, the quality of rice grains is improved.

• Journal of Korean Society of Transportation
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• v.36 no.2
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• pp.155-168
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• 2018

In this study, we studied the directional pattern of entering the intersection from the intersection upstream link prior to predicting short future (such as 5 or 10 minutes) intersection direction traffic volume on the interrupted flow, and examined the possibility of traffic volume prediction using traffic assignment model. The analysis method of this study is to investigate the similarity of patterns by performing cluster analysis with the ratio of traffic volume by intersection direction divided by 2 hours using taxi DTG (Digital Tachograph) data (1 week). Also, for linking with the result of the traffic assignment model, this study compares the impact area of 5 minutes or 10 minutes from the center of the intersection with the analysis result of taxi DTG data. To do this, we have developed an algorithm to set the impact area of intersection, using the taxi DTG data and traffic assignment model. As a result of the analysis, the intersection entry pattern of the taxi is grouped into 12, and the Cubic Clustering Criterion indicating the confidence level of clustering is 6.92. As a result of correlation analysis with the impact area of the traffic assignment model, the correlation coefficient for the impact area of 5 minutes was analyzed as 0.86, and significant results were obtained. However, it was analyzed that the correlation coefficient is slightly lowered to 0.69 in the impact area of 10 minutes from the center of the intersection, but this was due to insufficient accuracy of O/D (Origin/Destination) travel and network data. In future, if accuracy of traffic network and accuracy of O/D traffic by time are improved, it is expected that it will be able to utilize traffic volume data calculated from traffic assignment model when controlling traffic signals at intersections.

• Journal of Chest Surgery
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• v.36 no.5
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• pp.242-254
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• 2003

Background: Most of the studies conducted have investigated the beneficial effects of ischemic preconditioning on normothermic myocardial ischemia. However, the effect of preconditioning could be attenuated through the use of multidose cold cardioplegia as practiced in contemporary clinical heart surgical procedures. The purpose of this study was to investigate whether preconditioning improves postischemic cardiac function in a model of $25^{\circ}C$ moderate hypothermic ischemic heart induced by cold cardioplegia in isolated rat hearts. Material and Method: The isolated Sprague-Dawley rat hearts were randomly assigned to four groups All hearts were perfused at 37$^{\circ}C$ for 20 minutes with Krebs-Henseleit solution before the baseline hemodynamic data were obtained, Group 1 consisted of preconditioned hearts that received 3 minutes of global ischemic preconditioning at 37$^{\circ}C$, followed by 5 minutes of reperfusion before 120 minutes of cardioplegic arrest (n=6). Cold (4$^{\circ}C$) St. Thomas Hospital cardioplegia solution was infused to induce cardioplegic arrest. Maintaining the heart at $25^{\circ}C$, infusion of the cardioplegia solution was repeated every 20 minutes throughout the 120 minutes of ischemic period. Group 2 consisted of control hearts that underwent no manipulations between the periods of equilibrium and 120 minutes of cardioplegic arrest (n=6). After 2 hours of cardioplegic arrest, Krebs solution was infused and hemodynamic data were obtained for 30 minuts (group 1, 2: cold cardioplegia group). Group 3 received two episodes of ischemic preconditioning before 30 min of 37$^{\circ}C$ normothermic ischemia and 30 minutes of reperfusion (n=6) Group 4 soloed as ischemic controls for group 3 (group 3, 4: warm ischemia group). Result: Preconditioning did not influence parameters such as left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), rate-pressure product (RPP) and left ventricular dp/dt (LV dp/dt) in the cold cardioplegia group. (p=NS) However, preconditioning before warm ischemia attenuated the ischemia induced cardiac dysfunction, Improving the LVSP, LVEDP, RPP, and LV dp/dt. Less leakage of CPK and LDH were observed in the ischemic preconditioning group compared to the control group (p<0.05). Conclusion: Ischemic preconditioning improved postischemic cardiac function after warm ischemia, but did not protect cold cardioplegic hearts.

• Journal of Chest Surgery
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• v.35 no.3
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• pp.177-181
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• 2002

Background: Follow-up studies have shown that although outcomes have improved substantially over time, results of the Fontan operation and its modifications remain suboptimal. In this study, we reviewed our experience with the extracardiac conduit Fontan operation, with a focus early and midterm change of internal diameter of PTFE conduit. Material and Method: Between April 1997 and July 2000 were reviewed. Twelve patients (M:6, F:6, mean age 42.04 $\pm$ 12.43months, mean body weight 13.80$\pm$ 1.94kg) underwent extracardiac conduit Fontan operation with expanded PTFE graft. Mean cardiopulmonary bypass time was 109.7$\pm$26.99minute and mean operation time was 455$\pm$89.51minute. Intraoperative fenestration was performed in 10 patients. The aortic cross clamping was not performed in all patients. Result: There was no early deaths and no postoperative dysrhythmia. Postoperative protein losing enteropathy and prolonged pleural effusion occurred in 1(8.3%) and 4 patients(33.3%). Conduit patency was evaluated by magnetic resonance imaging studies. A 9.84$\pm$3.84% mean reduction in conduit internal diameter and there was no statistical correlation between the change of internal diameter of conduit and the postoperative duration after partial correlation analysis(r=0.019, p=0.955). Conclusion: These results demonstrate that the extracardiac conduit Fontan operation provies good early and midterm results and may reduce the prevalence of late arrhythmia. And there is no correlation between the change of internal diameter of conduit and the postoperative duration after extracardiac conduit Fontan operation with the expanded PTFE graft conduit.

• The Korean Journal of Nuclear Medicine
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• v.32 no.4
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• pp.382-390
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• 1998

Purpose: The purpose of this study was to evaluate the accuracy of radioactivity quantitation in Tc-99m SPECT by using combined scatter and attenuation correction. Materials and Methods: A cylindrical phantom which simulates tumors (T) and normal tissue (B) was filled with varying activity ratios of Tc-99m. We acquired emission scans of the phantom using a three-headed SPECT system (Trionix, Inc.) with two energy windows (photopeak window: $126{\sim}154keV$ and scatter window: $101{\sim}123keV$). We performed the scatter correction with dual-energy window subtraction method (k=0.4) and Chang attenuation correction. Three sets of SPECT images were reconstructed using combined scatter and attenuation correction (SC+AC), attenuation correction (AC) and without any correction (NONE). We compared T/B ratio, image contrast [(T-B)/(T+B)] and absolute radioactivity with true values. Results: SC+AC images had the highest mean values of T/B ratios. Image contrast was 0.92 in SC+AC, which was close to the true value of 1, and higher than AC (0.77) or NONE (0.80). Errors of true activity by SPECT images ranged from 1 to 11% for SC+AC, $22{\sim}47%$ for AC, and $2{\sim}16%$ for NONE in a phantom which was located 2.4cm from the phantom surface. In a phantom located 10.0cm from the surface, SC+AC underestimated by 24%, NONE 40%. However, AC overestimated by 10%. Conclusion: We conclude that accurate SPECT activity quantitation of Tc-99m distribution can be achieved by dual window scatter correction combind with attenuation correction.

• Journal of Chest Surgery
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• v.41 no.2
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• pp.177-188
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• 2008

Background: To evaluate the effects of inhaled nitric oxide (NO) and sphingosine 1-phosphate (S1P) as potential therapeutic agents of acute lung injury, we analyzed the morphology in vivo of the pulmonary microstructure using intravital videomicroscopy in a rat model of acute lung injury. Material and Method: Sprague Dawley rats were divided into five groups: a control group that underwent normal saline aspiration, an acute lung injury (ALI) group that underwent hydrochloric acid aspiration, and three treatment groups that underwent hydrochloric acid aspiration and were administered therapeutic agents- the S1P group, the NO group, and the S1P+NO group (n=7 per group). To quantify alveolar compliance and interstitial edema, the diameters of all measurable alveoli and interalveolar septa were averaged at one and two hours after aspiration. Alveolar compliance was determined according to diameter changes during the respiratory cycle and the change in tidal volume. Result: At two hours after aspiration, the mean alveolar compliance (% change) in the All group decreased significantly versus the control group of rats (respiratory cycle: 1.9% for the ALI group vs 6.5% for the control group, p=0.03; tidal volume: 3.2% for the ALI group vs 9.1% for the control group, p=0.003) and versus the NO group (tidal volume: 3.2% for the ALI group vs 16.9% for the NO group, p=0.001). At two hours after aspiration, the mean interalveolar septal thickness in the NO group tended to be smaller as compared to that in the All group ($15.2{\mu}m$ for the ALI group vs $12.3{\mu}m$ for the NO group, p=0.06). S1P did not exert a significant effect on the pulmonary microstructure of the injured rat lung. Conclusion: Improved alveolar compliance and reduced interstitial edema, observed by intravital videomicroscopy, suggest that inhaled NO ameliorates lung injury.