• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.83-94
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• 1999

The purpose of this study was to evaluate the changes of cancellous and cortical bone and the effect of estrogen in ovariectomized rats. Fifty female rats, 250gm in body weight, were divided into three groups : ovariectomized group(OVE), ovariectomized and estrogen-injected group(OVE-EST), and sham operated and estrogen-injected group(EST). Bilateral ovariectomy was performed at the onset of the experiment. In OVE-EST group and EST group, estrogen was injected $50{\mu}g/kg$ B.W. every other days from 3 weeks after surgery to sacrifice. Each five rats were sacrificed after 5, 6, 7 weeks. One side of mandibular body was radiographed with a soft x-ray apparatus(Hitex Co., Ltd., Japan). Thereafter the obtained microradiographs were used for the morphometric analysis using a Image analyzer. The morphometric analysis was perforrmed for parameters such as total bone area, cortex bone area and medullary bone area. The other side of the mandibular bone was decalcified and embedded in paraffin as using a general method. The specimens were sectioned and stained with Mallory's anilline blue and observed light microscopically. The results were as follows. 1 In all groups, the proportion of cortex to total bone area was not significantly different. 2. In ovariectomized(OVE) group, the proportion of marrow cavity to medullary bone area increased significantly from 5 to 7 weeks(p<0.05). In ovariectomized and estrogen-injected(OVE-EST) group, it decreased significantly at 7 weeks, and in estrogen-injected(EST) group, it decreased significantly from 6 weeks(p<0.05). 3. Microradiogram and histopathologic findings revealed that marrow cavity was enlarged and osteoclasts were observed around irregular bone surface in OVE group. In OVE-EST group, the size of marrow cavity at 7 weeks was similar to that of control group. In EST group, as dense trabecular bone increased from 5 to 7 weeks, marrow cavity decreased.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.168-174
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• 2011

Various La-based perovskite catalysts were prepared by a Pechini method, and they were applied to the low-temperature oxidation of odor compounds exhausted from waste food treatment process for effective deodorization. Quantitative and qualitative analyses of exhausted gas were conducted to measure the amount of major odor compounds with respect to operation time. A standard odor sample composed of major odor compounds was then prepared for use as a feed for oxidation reaction system. Various transition metal(M)-substituted La-based perovskite catalysts ($LaMO_{3}$: M=Cr, Mn, Fe, Co, and Ni) were prepared and applied to the oxidation of odor compounds in order to investigate the $LaNiO_3$ catalyst showed the best catalytic performance. Pt-substituted perovskite catalysts ($LaNi_{1-x}Pt_{x}O_{3}$: x=0, 0.03, 0.1, and 0.3) were then prepared for enhancing the catalytic performance. It was found that $LaNi_{0.9}Pt_{0.1}O_{3}$ catalyst served as the most efficient catalyst. Supported perovskite catalysts ($XLaNi_{0.9}Pt_{0.1}O_{3}/Al_{2}O_{3}$: X=perovskite content(wt%), 0, 10, 20, 30, 40, 50, and 100) were finally applied for the purpose of maximizing the catalytic performance of perovskite catalyst in the low-temperature oxidation reaction. Catalytic performance of $XLaNi_{0.9}Pt_{0.1}O_{3}/Al_{2}O_{3}$ catalysts showed a volcano-shaped curve with respect to perovskite content. Among the catalysts tested, $20LaNi_{0.9}Pt_{0.1}O_{3}$/$Al_{2}O_{3}$ catalyst exhibited the highest conversion of odor compounds of 88.7% at $180^{\circ}C$.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.13 no.2
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• pp.173-179
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• 2002

Background and Objectives : Intracordal cysts may occur secondary to voice abuse and overuse or may be secondary to a remnant of epithelium trapped within the lamina propria. They nay occur spontaneously or may be associated with poor vocal hygiene. As the cyst enlarges it can start to significantly affect the vibratory region of the vocal fold. Recently, with the advancement of the microsurgical technique and the laryngeal stroboscopy, correct diagnosis of intracordal cyst have been increased. The aims of this study is to review the important clinical characteristics of the intracordal cyst. Materials and Method : In the present study, 121 cases of the intracordal cyst were treated by the microsurgical technique. These lesions were diagnosed before the operation with indirect laryngoscopy, laryngeal endoscopy, laryngeal stroboscopy and confirmed with the findings observed during operations and the results of the biopsies. Results : The intracordal cysts were 121 cases in the 2595 patients who underwent laryngeal micorosurgery(4.7%). Ductal cyst were 88 cases and epidermoid cyst were 33 cases. The lesions are more frequent in women and anterior third of true vocal cord is more frequently involved site. With the indirect laryngoscopic examination, the ductal cysts are more frequently misdiagnosed as other diseases of the vocal cord such as vocal polyps or nodules. The degree of postoperative voice satisfaction is similar to that of vocal polyps. Conclusion : Intracordal cysts are very similar to the other mucosal disorders of the vocal cord and it may be misdiagnosed as vocal polyps or nodules, frequently. Therefore careful preoperative examinations for the vocal cord lesions with stroboscopy and other endoscopic instruments are important part of the correct diagnosis. An ideal treatment is enucleation of the cysts without upture of the cystic wall or injury of the lamina propria.

• Journal of Chest Surgery
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• v.35 no.11
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• pp.779-784
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• 2002

Recently, the number of coronary artery bypass surgery(CABG) is increasing according to the increasing incidence of coronary artery disease. However, CABG is not a definite corrective surgery; therefore, in some patients, redo-CABG may be required. We retrospectively reviewed our redo-CABG experiences to help future redo-CABG. Material and Method: From January 1991 to April 2001, 14 cases of redo-CABG were performed in Yonsei Cardiovascular Center(M:F＝12:2) and mean age was 61,7 $\pm$ 7.1(47-72) years. Mean time from 1st. CABG to redo-CABG was 121.9 $\pm$ 50.5(6.1-179.6) months. Thirteen cases were conventional on-pump CABG and one case was off-pump CABG. In two patients, mitral valve re-replacement and mitral valve repair were performed each. All redo-CABG were performed through mid-sternotomy. During redo-CABG, left internal mammary artery and saphenous vein grafts were used in 6 patients, left internal mammary artery and left radial artery grafts were used in 2 patients, left internal mammary artery and gastroepiploic artery were used in one patient and only greater saphenous veins were used in 5 cases(In one case, cephalic vein was also used). The number of mean distal anastomosis was 2.1 $\pm$ 0.9(1-4). Result: There were no operative death and no perioperative myocardial infarctions and cerebrovascular accidents or other heart related complications. Mean follow up duration was 40.1 $\pm$ 38.6(1.1-118.5) months. During follow up period, angina was re-developed in one patient 13 months after operation. Two patients died of end-stage renal failure 14.8 months and 116.3 months after redo-CABG, respectively. During follow up period, coronary angiography was performed in 3 patients, and all grafts were patent. At last follow up, mean Canadian class was 1.3. Kaplan-Meier survival at 9 years was 90.0 $\pm$ 9.5% and event free survival at 9 years was 71.4 $\pm$ 6.9%. Conclusion: After redo-CABG, all patients improved their angina symptom and daily activity. And long-term survival after redo-CABG was excellent. Therefore, if patients have indications for redo-CABG, thenredo-CABG must be strongly recommended and performed.

• Journal of Chest Surgery
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• v.40 no.5 s.274
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• pp.362-368
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• 2007

Background: Spontaneous pneumothorax patients with blebs or bullae are considered to be good candidates for operation, and various objective diagnostic modalities have been performed for detection of blebs and bullae. This study was performed to compare the efficacy of thoracoscopic examination with using a minimally invasive 2 mm thoracoscope with high-resolution computed tomography (HRCT) for treating primary spontaneous pneumothorax. Material and Method: From June 2001 to March 2002, 34 patients with spontaneous pneumothorax undewent study with 2 mm video-thoracoscopic examination and HRCT. We regarded a blob larger than 5 mm in diameter as significant. Standard thoracoscopic wedge resection was performed in 18 patients with significant blob via a 2 mm video-thoracoscopic examination. 1 patient incurred bleeding, and the remaining 15 patients were treated with pleural drainage. Result: Multiple or single blob lesions were detected by 2 mm video-thoracoscope in 52.9% (18/34) of the patients with primary pneumothorax. For a total of 19 patients who were operated on, the diagnostic accuracy of the 2 mm video-thoracoscopic examination for bullae and blob was 94.7% (18/19), which was superior to that of HRCT (73.7%, 14/19). At a mean follow-up of $30{\pm}3$ months, no recurrence occurred in both the operative group and the non-operative group. Conclusion: 2 mm video-thoracoscopic examination under local anesthesia has higher diagnostic accuracy than HRCT, and it is a useful alternative for determining the operative indications for spontaneous pneumothorax.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.405-416
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• 2008

Background: Spinal cord ischemic injury during thoracic and thoracoabdominal aortic surgeries remains a potentially devastating outcome despite using various methods of protection. Neuronal voltage-dependent sodium channel antagonists are known to provide neuroprotection in cerebral ischemic models. This study was designed to compare the neuroprotective effects of phenytoin with those of hypothermia in a rabbit model of spinal cord ischemia. Material and Method: Spinal cord ischemia was induced in New Zealand white rabbits by means of infrarenal aortic cross clamping for 25 minutes. Four groups of 8 animals each were studied. The control group and the hypothermia group received retrograde infusion of saline only ($22^{\circ}C$, 2 mL/min); the normothermic phenytoin group and the hypothermicphenytoin group received retrograde infusion of 100 mg of phenytoin at different rectal temperatures ($39^{\circ}C$ and $37^{\circ}C$, respectively) during the ischemic period. The neurologic function was assessed at 24 and 72 hours after the operation with using the modified Tarlov criteria. The spinal cords were harvested after the final neurologic examination for histopathological examination to objectively quantify the amount of neuronal damage. Result: No major adverse effects were observed with the retrograde phenytoin infusion during the aortic ischemic period. All the control rabbits became severely paraplegic, Both the phenytoin group and the hypothermia group had a better neurological status than did the control group (p < 0.05). The typical morphological changes that are characteristic of neuronal necrosis in the gray matter of the control animals were demonstrated by means of the histopathological examination, whereas phenytoin or hypothermia prevented or attenuated these necrotic phenomena (p < 0.05). The number of motor neuron cells positive for TUNEL staining was significantly reduced, to a similar extent, in the rabbits treated with phenytoin or hypothermia. Phenytoin and hypothermia had some additive neuroprotective effect, but there was no statistical significance between the two on the neurological and histopathological analysis. Conclusion: The neurological and histopathological analysis consistently demonstrated that both phenytoin and hypothermia may afford significant spinal cord protection to a similar extent during spinal cord ischemia in rabbits, although no significant additive effects were noticed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.521-528
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• 1988

Into the telecommunications industry, which had been monopolistic, a few advanced countries introduced competition through 70's and 80's. And this trend is going on worldwide. The introduction of competition into the industry is made mainly in the long distance, international and enhanced market. This liberalisation results from the fundamental change of the cost function. Suggesting that the cost comprises of that of the facility sector and that of the operation sector there exists the economies of scale in the facility sector in general. The major ground for the monopolistic industrial structure in the past was the natural monopoly depending on the economies of scale. But the rapid advance of the technology by a large margin. This decrease has resulted in the change of the cost function. That is while there exists the economies of scale in the smaller production scale, the average cost increases beyond a certain scale. This means that the natural monopoly collapsed, and that the competitive structure is more efficient than the monopolistic structure. But, because there exists economies of scale in the smaller scale, the desirable number of players, which could result in efficient industry structure depends on the market size. Such correlation between technological level market size and the degree of regulation is found in the case of U.S.A., Japan and U.K., where deregulation policy of the telecommunications market has already been carried out. In U.S.A., which has the largest market and the highest technological level the degree of regulation is lowest. Also in the order of Japan and U.K. the regulation is severer. Japan and U.K. are likely to liberalize still more, as the technology advances and the market grows. This article is just the beginning of the research, and this hypothesis requires more detailed research.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.560-569
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• 2016

Purpose The purpose of this study was not only to explore the factors associated with the survival of OHCA(Out-of-hospital Cardiac Arrest), but to provide ideas for improving the operation of emergency medical system in Korea. Method 90,734 OHCAs(Out-of-hospital Cardiac Arrest) with a cardiac etiology, who had been transported by 119 EMS ambulances for seven years from 2006 to 2012 in Korea, were analyzed. The data had a multilevel structure in that patient's survival in the same region is interrelated, so two-level (patient-region) logistic regression analysis was applied to adjust this correlation. Results The adjusted OR in group who were given CPR(Cardiopulmonary Resuscitation) by a bystander were 1.40 for survival to discharge. In addition, the adjusted OR in the group with an implementation of AED (automated external defibrillator) before arriving in hospital was 2.98 for survival to discharge. we categorized some continuous variables (number of emergency physician, OHCAs volume fo hospital, area deprivation level) into five quintiles. The adjusted OR in the number of emergency physician compared with Q1(lowest) was 1.29(Q2), 2.89(Q3), 3.39(Q4), 4.07(Q5), respectively. the adjusted OR in OHCAs volume of each hospital compared with Q1(lowest) was 2.06(Q2), 3.06(Q3), 3.46(Q4), 4.36(Q5), respectively. Lastly, the adjusted OR in deprivation level compared with Q1(least deprived area) was 0.72(Q4), 0.64(Q5) so that the adjusted OR of survival to discharge tended to decrease in more deprived districts. Conclusion The survival to discharge was better significantly in group given CPR by a bystander and with the implementation of AED before arriving in hospital. The survival to discharge tended to be significantly better in hospitals with a larger number of emergency physicians and higher volume of OHCAs in less deprived districts.

• Journal of Chest Surgery
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• v.43 no.1
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• pp.33-38
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• 2010

Background: The use of video-assisted thoracic surgery (VATS) to perform major pulmonary resection with systematic node dissection (SND) for lung cancer by is commonly used in clinics. However, the feasibility of SND by VATS remains controversial. Video-assisted mediastinal lymphadenectomy (VAMLA) increases the quality of mediastinal lymph node staging in lung cancer. The video-mediastinoscope allows systematic lymphadenectomy by bimanual preparation. This study was conducted to assess safety and usefulness and clinical feasibility of VAMLA expanding Linder-Dahan mediastinoscope with VATS lobectomy for left sided lung cancer. Material and Method: Between February 2004 to April 2008, a total 50 patients who underwent VATS lobectomy for left sided lung cancer were analyzed retrospectively. Thirty patients (group A) underwent VAMLA followed by VATS lymphadenectomy and 20 patients (group B) underwent VATS lymphadenectomy for SND. Result: There were no statistical differences in operation times, chest tube indwelling times, or hospital days between the 2 groups. The number of dissected total nodes (p=0.001) and N2 nodes (p=0.013) were higher in group A than in group B, but there was no difference in N1 nodes. Postoperative complications included 2 prolonged air leakages (${\geq}$10 days) in each group, one pneumonia in group A, and one vocal cord palsy in group B. There were no early operative mortalities. Conclusion: Mediastinal staging of resectable lung cancer is performed by VAMLA. This new technique is the basis for VATS lobectomy particularly for left-sided lung cancer, because a higher percentage of mediastinal lymph nodes undergo complete resection using VAMLA.

• Journal of Chest Surgery
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• v.32 no.1
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• pp.43-48
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• 1999

Background: Although treatment of spontaneous pneumothorax by video-assisted thoracic surgery(VATS) has generally shown better clinical results than conventional thoracotomy, treatment of spontaneous pneumothorax by midaxillary thoracotomy(MAXT) has also shown good clinical results. The author studied to compare the clinical results of MAXT group I and VATS group II. Material and Method : Group I included 30 midaxillary thoracotomy among 83 operative cases of spontaneous pneumothorax from Jan. 1992 to Dec. 1993. Group II included 30 VATS among 101 operative cases of pneumothorax from Jan. 1994 to Aug. 1995. The author selected the 30 patients, age 18 to 25 years, with recurrent spontaneous pneumothorax in each group. The author analyzed the operative indication, gender, operating time, amounts of the used staplers, tube drainage, total amounts of analgesics used during postoperative 24hr, tube stay time, postoperative complications and mortality. Result: The follow-up periods of both procedures were from 6 to 43 months. The operating time from start of skin incision to end of skin closure was 84.79${\pm}$21.70(from 40 to 150) minutes in MAXT group I and 108.8${\pm}$42.02(from 58 to 120) minutes in VATS group II(P<0.001). The numbers of the used staples useo was 1.31${\pm}$0.6(from 0 to 3) in group I and 3.41${\pm}$2.37(from 0 to 11) in group II. The amounts of postoperative 24hour tube drainage were 220.76${\pm}$106.73(from 65 to 400) ml in group I and 260.63${\pm}$233.18(from 70 to 320) in group II(P>0.05). The amounts of postoperative 24 hourly used analgesics(Tarasyn ) was 1.38${\pm}$1.32(from 0 to 5) amples in group I and 0.72${\pm}$1.02(from 0 to 4) amples in group II (P<0.05). The postoperative tube stay is 5.45${\pm}$30.9 (from 3 to 7) days in group I and 4.75${\pm}$3.1(9 from 2 to 14) days in group II(P>0.05). The number of complications after operations was 2 cases of prolonged air leakage in group I, and in group II. (P is not significant). The number of recurrence after the operation was one in group I and also one in group II(P is not significant). In conclusion, there were no statistical differences in the postoperative 24 hour chest tube drainage, days of postoperative tube stay, postoperative complications and recurrence in the analysis between group I and group II. Conclusion: The author found that group II of VATS between 18 years and 25 years of age in recurrent spontaneous pneumothorax, statistically, requires longer operative time, more number of autosuture staples and less postoperative analgesic dosage than the midaxillary thoracotomy group I.