• Tunnel and Underground Space
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• v.28 no.5
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• pp.400-425
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• 2018

This study presents the research results and current status of the DECOVALEX-2019 project Task B. Task B named 'Fault slip modelling' is aiming at developing a numerical method to simulate the coupled hydro-mechanical behavior of fault, including slip or reactivation, induced by water injection. The first research step of Task B is a benchmark simulation which is designed for the modelling teams to familiarize themselves with the problem and to set up their own codes to reproduce the hydro-mechanical coupling between the fault hydraulic transmissivity and the mechanically-induced displacement. We reproduced the coupled hydro-mechanical process of fault slip using TOUGH-FLAC simulator. The fluid flow along a fault was modelled with solid elements and governed by Darcy's law with the cubic law in TOUGH2, whereas the mechanical behavior of a single fault was represented by creating interface elements between two separating rock blocks in FLAC3D. A methodology to formulate the hydro-mechanical coupling relations of two different hydraulic aperture models and link the solid element of TOUGH2 and the interface element of FLAC3D was suggested. In addition, we developed a coupling module to update the changes in geometric features (mesh) and hydrological properties of fault caused by water injection at every calculation step for TOUGH-FLAC simulator. Then, the transient responses of the fault, including elastic deformation, reactivation, progressive evolutions of pathway, pressure distribution and water injection rate, to stepwise pressurization were examined during the simulations. The results of the simulations suggest that the developed model can provide a reasonable prediction of the hydro-mechanical behavior related to fault reactivation. The numerical model will be enhanced by continuing collaboration and interaction with other research teams of DECOLVAEX-2019 Task B and validated using the field data from fault activation experiments in a further study.

• The Korean Journal of Nuclear Medicine
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• v.20 no.2
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• pp.85-100
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• 1986

To evaluate the clinical and pathogenetic roles of TSH receptor antibodies in autoimmune thyroid diseases, TBII were measured by TSH-radioreceptor assay methods in 352 patients with Graves' disease, 108 patients with other thyroid diseases and 69 normal persons. The normal range of TBII activity was less than 15%. The frequencies of detectable TBII in 169 patients with untreated Graves' disease, 31 patients with hyperthyroidism under treatment and 70 patients with euthyrodism under treatment were 92.4%, 87.1% and 54.3% respectively. However 12 (21.8%) out of 55 patients who have been in remission more than one year after discontinuation of antithyroid drugs treatment had detectable TBII activities in their sera. In 196 patients with untreated Graves' disease, the frequency of TBII increased by increasing size of goiter and the frequency of proptosis was significantly high in patients whose TBII activities were more than 60%. TBII activities were roughly correlated with total $T_3,\;T_4$ and free $T_4$ index but low $\gamma^2$ value(less than 0.1). In 67 patients with Graves' disease who were positive TBII before antithyroid drugs treatment, TBII activities began to decrease from the third months and it was converted to negative in 35.8% of patients at 12 months after treatment. There were no significant differences of the declining and disappearing rates of TBII activities between high dose and conventional dose groups. TBII activities were significantly increased initially (2-4 months) and then began to decrease from 5-9 months after $^{131}I$ treatment. There were two groups, one whose TBII activities decreased gradually and the other did not change untill 12 months after subtotal thyroidectomy. Although preoperative clinical and laboratory findings of both groups were not different, TBII activities of non-decreasing group were significantly higher than those of decreasing group$(74.6{\pm}18.6%\;vs\;39.2{\pm}15.2%;\;P<0.01)$. Thirty three(55.9%) out of 59 patients with Graves' disease relapsed within 1 year after discontinuation of antithyroid drugs. The positive rate of TBII at the end of antithyroid drug treatment in relapse group(n=33) was significantly higher than those in remission group (n=26) (63.6% vs 23.1%; P < 0.05). The mean value of TBII activities at the end of antithyroid drug treatment in relapse group was significantly elevated $(29.7{\pm}21.4%\;vs\;14.7{\pm}11.1%,\;P<0.05)$. Positive predictive value of TBII for relapse was 77.8%, which was not different from those of TRH nonresponsiveness(78.6%). The frequencies of detectable TBII in 68 patients with Hashimoto's thyroiditis, 10 patients with painless thyroiditis and 5 patients subacute thyroiditis were 14.7%, 20% and 0%, respectively. However in 25 patients with primary nongoitrous myxedema, 11 patients(44%) showed TBII activities in their sera. 9 out of 11 patients who had TBII activities in their sera showed high TBII activities(more than 70% binding inhibition) and their IgG concentrations showing 50% binding inhibition of $^{125}I-bTSH$ to the TSH receptor were ranges of 0.1-2.6 mg/dl. One patient who had high titer of TBII in her serum delivered a hypothyroid baby due to transplacental transfer of maternal TBII. These findings suggested that 1) TSH receptor antibodies are closely related to a pathogenetic factor of Graves' hyperthyroidism and of some patients with primary non-goitrous myxedema, 2) measurement of TSH receptor antibodies is helpful in evaluating the clinical outcome of patients with Graves' disease during antithyroid drug treatment and in predicting the neonatal transient hypothyroidism of baby delivered from primary myxedema patients. 3) there are 2 or more different types of TSH receptor antibodies in autoimmune thyroid diseases including one which stimulates thyroid by binding to the TSH receptor and another which blocks adenylate cyclase stimulation by TSH.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.13 no.2
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• pp.128-133
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• 2010

Purpose: Intussusception is one of the most common causes of an acute abdomen in infancy. The majority of pediatric cases of intussusception are of the ileocolic type and usually idiopathic. Small bowel intussusception is rarely diagnosed in children, and few cases have been reported. The purpose of this study was to determine the clinical features and causes of small bowel intussusception in children. Methods: We retrospectively reviewed the clinical and radiologic findings of 21 children with small bowel intussusception who were admitted to Seoul National University Children's Hospital between March 2005 and January 2010. Results: The clinical presentation of small bowel intussusception included abdominal pain or irritability (85%), vomiting (23%), fever (14%), bloody stools (14%), and abdominal masses (4%). Six patients required surgical management. Ultrasonography showed that the mean diameter of the lesions and mean thickness of the outer rims were 1.6${\pm}$0.7 and 1.7${\pm}$1.8 mm, respectively. Eleven lesions were located in the left abdominal or paraumbilical regions. Children who underwent surgical management were older than children with transient small bowel intussusception (mean age, 51 vs. 109 months). The mean diameter of the lesions and mean thickness of the outer rims were greater in the surgically-managed group. The location of intussusception was not significantly different between the two groups. Conclusion: Small bowel intussusception was spontaneously reduced in a large number of pediatric patients. However, sonographic demonstration of larger size, older age, and pathologic lead point warrant surgical intervention.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.11 no.1
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• pp.21-27
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• 2008

Purpose: The aim of this survey was to analyze the choice of sedative drugs and their side effects during pediatric endoscopic sedation in Korea. We also evaluated doctors, caretakers and patient satisfaction with the procedures. Methods: Between June 2006 and July 2006, a 16-item survey regarding current sedation practices, during one month, was mailed to 28 hospitals in Korea. The results of the survey responses were then analyzed. Results: Endoscopy performed under conscious sedation was reported in 89.0% of the responders and endoscopy under general anesthesia in 0.9% of 465 endoscopic procedures. Endoscopy under conscious sedation was performed in 89.1% for upper gastrointestinal endoscopy (GFS) and 88.1% for lower GFS. Midazolam was used for conscious sedation during the endoscopy in 84.5% of cases and propofol was used in two cases (0.5%). In addition, a bezodiazepine/opioid combination was used iin 84.6% (44 cases) for lower GFS. Patients were monitored with pulse oxymetry, EKG (91.4%) as well as automatic BP (5.1%). Transient hypoxia was the only side effect noted and was treated with supplemental oxygen (4.6%). Flumazenil was used in 2.71% of cases. The choice of sedation was made by the endoscopist (84%). The satisfaction rate for endoscopists was 68%, and for the patients and caretakers was 84% (as reported by the endoscopists). Conclusion: Midazolam was used only for the upper GFS and benzodiazepine/opioid combination was used for the lower GFS in Korea. The rate of satisfaction was relatively high and there were no significant side effects noted during the endoscopy under conscious sedation.

• Journal of Chest Surgery
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• v.30 no.3
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• pp.275-281
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• 1997

The radial artery as a graft for myocardial revascularization was introduced by Carpentier in the early 1970s. Mid-term results were unfortunately discoura ing, and the clinical experience with this graft was interrupted. At the end of the 1980s, these authors reproposed the same arterial conduit with more satisfying results, because of improved technique and pharmacological management of the graft. Between October 1994 and July 1995, 36 patients underwent myocardial revascularization with a radial artery graft in Seiong General Hospital. Left internal mammary artery was concomitantly used as a pedicled Vift in 34 patients. Fifteen patients (42%) had a complete arterial waft revascularization. A total of 12) distal anastomoses were performed (average 3.4 per patient), including 36 left internal mammary artery wafts (two sequential in 2 patients), and 23 saphenous vein grafts. The remaining 64 distal anastomoses were perFormed with radial artery grafts (mean 1.8 per patient). The radial arteries were anastomosed to the circumflex (n=38), diagonal (n= 18), right coronary(n=G), and left anterior descending coronary artery(n=2). The percent ge of radial artery graft anastomoses (64) to the total anastomoses(123) was 52%. The radial artery was used as a single graft in 10 patients, as a sequential graft in 25 patients, and two grafts in 1 patient. Twenty patients underwent associated procedures coronary endarterectomy (14), coronary artery patch angioplasty (4), mitral valve repair (1), and repair of ventricular septal rupture (1). One patient died of low cardiac output syndrome and the others had no perioperative myocardial infarction. There are no ischemic and functional complications in the arm or hand aftcr removal of the radial artery. Only 1 patient required reexploration of the am, for the hematoma evacuation, and 2 patients complained transient thumb dysesthesia of the side of the havested arm. This dysesthesia improved within one month. Postoperative angiovaphic controls were obtained in 11 patients(31%) postoperative 79 to 210 days (mean 126 days). The patency rate were as follows : left internal mammary artery (100%), saphcnous vein (100%), and radial artery(95%). We concluded that the radial artery is useful alternative graft, but long term clinical and angiographic studies are required to derterminc whether wider application is warranted.

• Journal of Chest Surgery
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• v.39 no.5 s.262
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• pp.387-393
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• 2006

Background: Esophageal perforation is an uncommon problem, but it is associated with high mortality. We performed a retrospective review of patients with instrumental esophageal perforation to assess the outcome of current management techniques. Material and Method: We retrospectively analyzed all cases of instrumental esophageal perforation diagnosed at our hospital from January 1999 through to March 2005. The study group consisted of 12 patients (8 women and 4 men) with a mean age of 48.8 years (range, $21{\sim}83$ years). We reviewed the effects of the surgical or medical treatments in various conditions of patients, such as of various sites of perforation and time delayed after injury. Result: Perforations were due to diagnostic endoscopy (50.0%, 6/12), esophageal bougination for benign stricture (33.3%, 4/12), endoscopic port insertion (8.3%, 1/12), and tracheal intubation (8.3%, 1/12). The perforated sites were thoracic in 7 patients and cervical in 5. The treatment included resection and reconstruction (5 cases), incision and drainage (4 cases), medical treatment (2 cases), and closed thoracostomy drainage only (1 case). Post-operative complications of transient pneumonia and wound infection were developed in 1 patient respectively. Both occurred in two patients with diffuse mediastinal abscess formation. The overall mortality was 8.3% (1/12) in one old patient who was managed medically for cervical esophageal perforation. Conclusion: We concluded that surgical treatment for esophageal perforations was safe and effective whether diagnosed early or lately.

• Journal of Chest Surgery
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• v.31 no.8
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• pp.739-748
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• 1998

Background: It has been well documented that transient occlusion of the coronary artery causes myocardial ischemia and finally cell death when ischemia is sustained for more than 20 minutes. Extensive studies have revealed that ischemic myocardium cannot recover without reperfusion by adequate restoration of blood flow, however, reperfusion can cause long-lasting cardiac dysfunction and aggravation of structural damage. The author therefore attempted to examine the effect of postischemic reperfusion on myocardial ultrastructure and to determine the rationales for recanalization therapy to salvage ischemic myocardium. Materials and methods: Young Holstein-Friesian cows(130∼140 Kg body weight; n=40) of both sexes, maintained with nutritionally balanced diet and under constant conditions, were used. The left anterior descending coronary artery(LAD) was occluded by ligation with 4-0 silk snare for 20 minutes and recanalized by release of the ligation under continuous intravenous drip anesthesia with sodium pentobarbital(0.15 mg/Kg/min). Drill biopsies of the risk area (antero-lateral wall) were performed at just on reperfusion(5 minutes), 1-, 2-, 3-, 6-, 12-hours after recanalization, and at 1-hour assist(only with mechanical respiration and fluid replacement) after 12-hour recanalization. The materials were subdivided into subepicardial and subendocardial tissues. Tissue samples were examined with a transmission electron microscope (Philips EM 300) at the accelerating voltage of 60 KeV. Results: After a 20-minute ligation of the LAD, myocytes showed slight to moderate degree of ultrastructural changes including subsarcolemmal bleb formation, loss of nuclear matrix, clumping of chromatin and margination, mitochondrial destruction, and contracture of sarcomeres. However, microvascular structures were relatively well preserved. After 1-hour reperfusion, nuclear and mitochondrial matrices reappeared and intravascular plugging by polymorphonuclear leukocytes or platelets was observed. However, nucleoli and intramitochondrial granules reappeared within 3 hours of reperfusion and a large number of myocytes were recovered progressively within 6 hours of reperfusion. Recovery was apparent in the subepicardial myocytes and there were no distinct changes in the ultrastructure except narrowed lumen of the microvessels in the later period of reperfusion. Conclusions: It is likely that the ischemic myocardium could not be salvaged without adequate restoration of coronary flow and that the microvasculature is more resistant to reversible period of ischemia than subendocardium and subepicardium. Therefore, thrombolysis and/or angioplasty may be a rational method of therapy for coronarogenic myocardial ischemia. However, it may take a relatively longer period of time to recover from ischemic insult and reperfusion injury should be considered.

• Journal of Chest Surgery
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• v.42 no.1
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• pp.14-21
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• 2009

Background: Postoperative atrial fibrillation (AF) is a common complication after coronary artery bypass graft (CABG) surgery. Although postoperative AF is regarded as benign, transient and self-limited, it has been associated with increased morbidity, thromboembolic events and an increased duration and cost of hospitalization. Material and Method: From January 1994 to December 2007, 190 patients that had isolated CABG surgery were divided into two groups. Group 1 (n=139) involved those who had postoperative atrial fibrillation, and group 2 (n=51) did not have any such events. We reviewed the medical records retrospectively including the incidence of postoperative AF, patient characteristics, surgery related factors and the outcome of the patients with postoperative AF. Result: The frequency of postoperative AF was 26.8%, the conversion rate to regular sinus rhythm before discharge was 82.4%; 82.4% of the AF developed within the first three postoperative days. Although the postoperative AF group was significantly older and had a prolonged postoperative Intensive care unit (ICU) stay, there was no difference in the aortic crossclamp time or duration of hospitalization. No spontaneous defibrillation at declamping, and longer duration of cardiopulmonary bypass were significantly related to the development of postoperative AF. However, postoperative treatment with a beta blocker was associated with a decreased incidence of postoperative AF. The multivariate analysis showed that age and ICU stay were significantly associated with the development of POAF. Spontaneous defibrillation and postoperative beta blocker treatment were significantly associated with a decreased frequency of POAF. Conclusion: AF after CABG surgery is a common complication associated with increased morbidity and a longer ICU stay. Therefore, various strategies aimed at reducing AF, and its complications, such as postoperative treatment with a beta blocker should be considered.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.483-488
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• 2007

Current feeder system (CFS) for Korea superconducting tokamak advanced research(KSTAR) project plays a role to interconnect magnet power supply (MPS) and superconducting (SC) magnets through the normal bus-bar at the room temperature(300 K) environment and the SC bus-line at the low temperature (4.5 K) environment. It is divided by two systems, i.e., toroidal field system which operates at 35 kA DC currents and poloidal field system wherein 20$\sim$26 kA pulsed currents are applied during 350 s transient time. Aside from the vacuum system of main cryostat, an independent vacuum system was constructed for the CFS in which a roughing system is consisted by a rotary and a mechanical booster pump and a high vacuum system is developed by four cryo-pumps with one dry pump as a backing pump. A self interlock and its control system, and a supervisory interlock and its control system are also established for the operational reliability as well. The entire CFS was completely tested including the reliability of local/supervisory control/interlock, helium gas leakage, vacuum pressure, and so on.

• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.335-345
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• 1996

A critical role of oxygen-derived free radicals has been implicated in ischemia/reperfusion (I/R)-induced brain damage. In this study, we have produced experimental I/R to the brains of Mongolian gerbil (Meriones unguiculatus) by a transient occlusion and release of the common carotid arteries. We have attempted to determine whether the oxidative stress is generated upon I/R and whether this oxidative stress is linked to the cell damage. Since hippocampus has been suggested as one of the most vulnerable regions of the brain to the oxidative stress, we analyzed samples from hippocampus in comparison with those from cortex. In addition, we have examined the expression of heat shock protein 70kD species (HSP70) in these regions in order to evaluate a possible role of this protein in I/R-induced brain damage. To determine whether the oxidative stress is produced upon I/R, we measured the glutathione oxidation, GSSG/ (GSH + 2xGSSG), as an index of oxidative stress. We found an increase of the glutathione oxidation primarily in hippocampus upon I/R. To determine whether this oxidative stress is linked to the cell damage, we measured the degree of lipid peroxidation upon I/R. We found an increase of lipid peroxidation in both regions. However, the magnitude of increases was greater in hippocampus than in cortex. In addition, we found that changes in both the magnitude and the temporal patterns of glutathione oxidation closely correlated with those of lipid peroxidation. Our study provides biochemical evidences that the oxidative stress is generated upon I/R and this oxidative stress is linked to the oxidative cell damage. Our study also provides evidences that the degree of oxidative stress as well as oxidative cell damage is greater in hippocampus than in cortex. We could not find difference in the basal level of HSP70 expression between hippocampus and cortex, indicating that the intrinsic vulnerability of hippocampus cannot be explained by the lower level of HSP70 expression. We did find, however, that the induction of HSP70 expression upon I/R was impaired in the hippocampus. This impairment appeared to be at the transcriptional level. These results suggest that the measurement of HSP70 induction may be employed as a useful predictor of differential cellular susceptibilities to the I/R-induced brain damage.