• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.37-43
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• 2009

Temperature and injection current dependence of electroluminescence(EL) spectral intensity of the $In_xGa_{1-x}N$/GaN multi-quantum wells(MQW) have been studied over a wide temperature range and as a function of injection current level. It is found that a temperature-dependent variation pattern of the EL efficiency under very low and high injection currents shows a drastic difference. This unique EL efficiency variation pattern with temperature and current can be explained field effects due to the driving forward bias in presence of internal(piezo and spontaneous polarization) fields. Increase of the indium content in $In_xGa_{1-x}N$/GaN multiple quantum wells gives rise to a redshift of 80 meV and 22 meV for green and blue MQW, respectively. It can be explained by carrier localization by potential fluctuation of multiple quantum well and MQW structures also shows a keen difference owing to the different indium content in InGaN/GaN MQW.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.348-372
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• 2023

In relation to the high-level radioactive waste disposal project in deep fractured rock aquifer environments, it is essential to evaluate hydrogeological characteristics for evaluating the suitability of the site and operational stability. Such subsurface hydrogeological data is obtained through in-situ tests using boreholes excavated at the target site. The accuracy and reliability of the investigation results are directly related to the selection of appropriate test methods, the performance of the investigation system, standardization of the investigation procedure. In this report, we introduce the detailed procedures for the representative test method, the constant pressure injection test (CPIT), which is used to determine the key hydrogeological parameters of the subsurface fractured rock aquifer, namely hydraulic conductivity and storativity. This report further refines the standard test method suggested by the KSRM in 2022 and includes practical field application case conducted in volcanic rock aquifers where this investigation procedure has been applied.

• Smart Structures and Systems
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• v.3 no.1
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• pp.1-22
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• 2007

The energy efficiency of a self-powered wireless sensing system for pressure monitoring in injection molding is analyzed using Bond graph models. The sensing system, located within the mold cavity, consists of an energy converter, an energy modulator, and a ultrasonic signal transmitter. Pressure variation in the mold cavity is extracted by the energy converter and transmitted through the mold steel to a signal receiver located outside of the mold, in the form of ultrasound pulse trains. Through Bond graph models, the energy efficiency of the sensing system is characterized as a function of the configuration of a piezoceramic stack within the energy converter, the pulsing cycle of the energy modulator, and the thicknesses of the various layers that make up the ultrasonic signal transmitter. The obtained energy models are subsequently utilized to identify the minimum level of signal intensity required to ensure successful detection of the ultrasound pulse trains by the signal receiver. The Bond graph models established have shown to be useful in optimizing the design of the various constituent components within the sensing system to achieve high energy conversion efficiency under a compact size, which are critical to successful embedment within the mold structure.

• Journal of Information Display
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• v.7 no.2
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• pp.26-30
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• 2006

Insertion of a thin lithium fluoride (TLF) layer between an emitting layer (EML) and an electron transporting layer has resumed in the developement of a highly efficient and bright organic light-emitting diode (OLED). Comparing with the performance of the device as a function of position with the TLF layer in tris-(8-hydroxyquinoline) aluminum $(Alq_{3})$, we propose the optimal position for the TLF layer in the stacked structure. The fabricated OLED shows a luminance efficiency of more than 20 cd/A, a power efficiency of 12 Im/W (at 20 mA/$cm^{2}$), and a luminance of more than 22 000 cd/$m^{2}$ (at 100 mA/$cm^{2}$), respectively. We suggest that the enhanced performance of the OLED is probably attributed to the improvement of carrier balance to achieve a high level of recombination efficiency in an EML.

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.466-476
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• 1998

We investigated the in vivo effect of an aqueous extract (referred to as EF) from Eriobotryae folium on glucokinase and hexokinase activities of diabetes mellitus induced by $interleukin-1{\beta}\;(IL-1{\beta})$. After 1 week of $IL-1{\beta}$ injection, the levels of serum glucose concentration and insulin secretion were dramatically increased. However, the insulin secretion was decreased with administration of EF. The level of glucose concentration was decreased by EF administration. Furthermore, it was observed that EF was effective in recovering the levels of insulin secretion. Enzyme activities of the glucokinase and hexokinase, which are key enzymes of glucose phosphorylastion, were decreased by $IL-1{\beta}$. EF administration to the mice allowed proportional increasing by stimulation of induction of enzyme activities as high as normal group. These results suggested that EF is highly effective in treatment of diabetes mellitus induce by $IL-1{\beta}$.

• Journal of Korean Neurosurgical Society
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• v.56 no.1
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• pp.71-74
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• 2014

Cancer-related facial pain refractory to pharmacologic management or nondestructive means is a major indication for destructive pain surgery. Stereotactic mesencephalotomy can be a valuable procedure in the management of cancer pain involving the upper extremities or the face, with the assistance of magnetic resonance imaging (MRI) and electrophysiologic mapping. A 72-year-old man presented with a 3-year history of intractable left-sided facial pain. When pharmacologic and nondestructive measures failed to provide pain alleviation, he was reexamined and diagnosed with inoperable hard palate cancer with intracranial extension. During the concurrent chemoradiation treatment, his cancer-related facial pain was aggravated and became medically intractable. After careful consideration, MRI-based stereotactic mesencephalotomy was performed at a point 5 mm behind the posterior commissure, 6 mm lateral to and 5 mm below the intercommissural plane using a 2-mm electrode, with the temperature of the electrode raised to $80^{\circ}C$ for 60 seconds. Up until now, the pain has been relatively well-controlled by intermittent intraventricular morphine injection and oral opioids, with the pain level remaining at visual analogue scale 4 or 5. Stereotactic mesencephalotomy with the use of high-resolution MRI and electrophysiologic localization is a valuable procedure in patients with cancer-related facial pain.

• Journal of Yeungnam Medical Science
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• v.32 no.1
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• pp.17-21
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• 2015

Amlodipine, a calcium channel blocker of the dihydropyridine group, is commonly used in management of hypertension, angina, and myocardial infarction. Amlodipine overdose, characterized by severe hypotension, arrythmias, and pulmonary edema, has seldom been reported in Korean literature. We report on a fatal case of amlodipine intoxication with complications including rhabdomyolysis and oliguric acute kidney injury. A 70-year-old woman with a medical history of hypertension was presented at the author's hospital 6 hours after ingestion of 50 amlodipine (norvasc) tablets (total dosage 250 mg) in an attempted suicide. Her laboratory tests showed a serum creatinine level of 2.5 mg/dL, with elevated serum creatine phosphokinase and myoglobin. The patient was initially treated with fluids, alkali, calcium gluconate, glucagon, and vasopressors without a hemodynamic effect. High-dose insulin therapy was also started with a bolus injection of regular insulin (RI), followed by continuous infusion of RI and 50% dextrose with water. Despite intensive treatment including insulin therapy, inotropics, mechanical ventilation, and continuous venovenous hemodiafiltration, the patient died of refractory shock and cardiac arrest with no signs of renal recovery 116 hours after her hospital admission.

• Environmental Analysis Health and Toxicology
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• v.19 no.3
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• pp.287-294
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• 2004

Diabetic complication is one of major risk factors leading to vascular disease such as atherosclerosis, stroke, coronary heart disease and etc. Several factors affecting the acceleration of diabetic vascular complication have been known such as hypertension, hyperlipidemia, immune complex and genetic factors. To screen and develop new therapeutics agents for diabetic vascular complication, it is strongly needed to develop animal models for diabetic complications. However in rodents models, diabetic complications is not well developed. Furthermore to assess the possibility of new therapeutics for diabetic vascular complications, diabetic animal models which have the risk factors of diabetic complications is needed. We aim to develop and establish an diabetic animal model which have diabetic complications with hyperlipidemia which is one of risk factors for diabetic complications. We induced insulin -dependent diabetes by intra. venous injection of streptozotocin (35 mg/kg/day) in RICO rats which is a spontaneous animal model for hyperlipidemia. Our models (STZ RICO) showed hyperglycemia, persistent high level of plasma cholesterol and triglyceridemia with severe diabetic renal changes until 28 weeks after induction of diabetes. STZ-RICO rats could be used for the evaluations of newly developed diabetic drugs.

• Molecular & Cellular Toxicology
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• v.3 no.2
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• pp.119-126
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• 2007

1, 1-dichloroethylene (DCE) is well known hepatotoxicant as a model acute hepatotoxicity and selectively injure the bile canalicular membrane of centrilobular hepatocytes. In this study, we investigated hepatic gene expression and histopathological changes in response to DCE treatment. DCE was administered once daily at 20 mg/kg up to 14 days via intraperitoneal injection. Five mice were used in each test group and were sacrificed at 1, 7, and 14 days. Serum biochemical and histopathological analysis were performed for evaluation of hepatotoxicity level. Direct bilirubin and total bilirubin activities were slightly elevated in treated group at 7 days. DCE treatment for 7 days resulted in centrilobular hepatocyte hypertrophy and hepatocyte vacuolation, and mild hepatocyte vacuolation and high hepatocyte basophilia were observed in 14 days treated group. One hundred twenty three up-regulated genes and 445 down-regulated genes with over 2-fold changes between treated and control group at each time point were used for pathway analysis. These data may contribute in understanding the molecular mechanism DCE-induced hepatotoxicity.

• YAKHAK HOEJI
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• v.45 no.1
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• pp.55-63
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• 2001

In order to investigate the effects of bisphenol A (BPA) on immune system in mice we examined the various immunological parameters. After single oral administration of BPA to female ICR mice, the weights of bodies and lymphoid organs, splenic cellularity and hematological parameters were examined on day 2 and 7. Among them WBC and splenic cellularity were slightly decreased on day 2. To assess the effects of BPA on humoral immune responses, splenic IgM plaque forming cell (PFC) and serum IgM were assayed. When BPA was administered after immunization with SRBC, but not before immunization, IgM PFC against SRBC was significantly lowered in a dose dependent manner. Serum IgM level was also decreased on day 4 when high dose (2000 mg/kg) of BPA was administrated after injection of OVA-antigen. The indexes of splenocyte proliferation (SP) to concanavalin A (Con A) and bacterial lipopolysaccharide (LPS) were measured in vitro by MTT assay. At low concentration BPA slightly increased splenocyte proliferation but at higher concentration it showed significant inhibitory effects on cell proliferation. Mitogen-stimulated SP was also determined with spleen cells from BPA treated mice. Con A-induced SP was slightly decreased and LPS-induced SP was especially inhibited at 1000 mg/kg and 2000 mg/kg of BPA. These results indicate that BPA is able to acutly evoke humoral and cell mediated immune suppression in mice.