• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.391-400
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• 2008

Multi-pulse topology of converters using elementary six-pulse GTO - VSC (gate turn off based voltage source converter) operated under fundamental frequency switching (FFS) control is widely adopted in high power rating static synchronous compensators (STATCOM). Practically, a 48-pulse ($6{\times}8$ pulse) configuration is used with the phase angle control algorithm employing proportional and integral (PI) control methodology. These kinds of controllers, for example the ${\pm}80MVAR$ compensator at Inuyama switching station, KEPCO, Japan, employs two stages of magnetics viz. intermediate transformers (as many as VSCs) and a main coupling transformer to minimize harmonics distortion in the line and to achieve a desired operational efficiency. The magnetic circuit needs altogether nine transformers of which eight are phase shifting transformers (PST) used in the intermediate stage, each rating equal to or more than one eighth of the compensator rating, and the other one is the main coupling transformer having a power rating equal to that of the compensator. In this paper, a two-level 48-pulse ${\pm}100MVAR$ STATCOM is proposed where eight, six-pulse GTO-VSC are employed and magnetics is simplified to single-stage using four transformers of which three are PSTs and the other is a normal transformer. Thus, it reduces the magnetics to half of the value needed in the commercially available compensator. By adopting the simple PI-controllers, the model is simulated in a MATLAB environment by SimPowerSystems toolbox for voltage regulation in the transmission system. The simulation results show that the THD levels in line voltage and current are well below the limiting values specified in the IEEE Std 519-1992 for harmonic control in electrical power systems. The controller performance is observed reasonably well during capacitive and inductive modes of operation.

• Journal of Yeungnam Medical Science
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• v.14 no.2
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• pp.459-466
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• 1997

Hyperparathyroidism due to parathyroid cancer is rare. It is difficult to diagnose preoperatively but there should be an increased index of suspicion in those parathyroid patients with palpable neck masses, profound hypercalcemia(greater than 14mg/dl), marked increase of the parathyroid hormone level to greater than twice normal, and significant metabolic complications. In parathyroid cancer, systemic calcinosis is an extremely rare manifestation. The most common metastatic calcification site is lung and the other involved site is stomach, liver, skin and heart. After resection of parathyroid tumor, this systemic calcinosis is self-limiting. We experienced a patient with primary hyperparathyroidsm, presented with metastatic calcification in the lung and stomach disappeared by successful parathyroidectomy.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.138-140
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• 2002

The spinal cord dose is the one of the limiting factor for the radiation treatment of the head & neck (H&N) or the thorax region. Due to the fact that the cord is the elongated shaped structure, it is not an easy task to maintain the cord dose within the clinically acceptable dose range. To overcome this problem, the spinal cord partial block technique (PBT) with the dynamic Multi-Leaf Collimator (dMLC) has been developed. Three dimension (3D) conformal beam directions, which minimize the coverage of the normal organs such as the lung and the parotid gland, were chosen. The PBT field shape for each field was designed to shield the spinal cord with the dMLC. The transmission factors were determined by the forward calculation method. The plan comparisons between the conventional 3D conformal therapy plan and the PTB plan were performed to evaluate the validity of this technique. The conformity index (CI) and the dose volume histogram (DVH) were used as the plan comparison indices. A series of quality assurance (QA) was performed to guarantee the reliable treatment. The QA consisted of the film dosimetry for the verification of the dose distribution and the point measurements. The PBT plan always generated better results than the conventional 3D conformal plan. The PBT was proved to be useful for the H&N and thorax region.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7371-7375
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• 2014

Background: Concurrent chemo-radiotherapy is the recommended standard treatment modality for patients with locally advanced lung cancer. The purpose of three-dimensional conformal radiotherapy (3DCRT) is to minimize normal tissue damage while a high dose can be delivered to the tumor. The most common dose limiting side effect of thoracic RT is radiation pneumonia (RP). In this study we evaluated the relationship between dose-volume histogram parameters and radiation pneumonitis. This study targeted prediction of the possible development of RP and evaluation of the relationship between dose-volume histogram (DVH) parameters and RP in patients undergoing 3DCRT. Materials and Methods: DVHs of 41 lung cancer patients treated with 3DCRT were evaluated with respect to the development of grade ${\geq}2$ RP by excluding gross tumor volume (GTV) and planned target volume (PTV) from total (TL) and ipsilateral (IPSI) lung volume. Results: Were admitted statistically significant for p<0.05. Conclusions: The cut-off values for V5, V13, V20, V30, V45 and the mean dose of TL-GTV; and V13, V20,V30 and the mean dose of TL-PTV were statistically significant for the development of Grade ${\geq}2$ RP. No statistically significant results related to the development of Grade ${\geq}2$ RP were observed for the ipsilateral lung and the evaluation of PTV volume. A controlled and careful evaluation of the dose-volume histograms is important to assess Grade ${\geq}2$ RP development of the lung cancer patients treated with concurrent chemo-radiotherapy. In the light of the obtained data it can be said that RP development may be avoided by the proper analysis of the dose volume histograms and the application of optimal treatment plans.

• Journal of the Korean Data and Information Science Society
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• v.24 no.3
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• pp.465-475
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• 2013

Higher quality level is generally perceived by customers as improved performance by assigning a correspondingly higher satisfaction score. Usually, the quality level is measured by process capability indices. The index is used to determine whether a production process is capable of producing items within a specified tolerance. Some useful process capability indices $C_p$, $C_{pk}$ and $C_{pm}$ have been widely used in six sigma industries to assess process performance. Most evaluations on process capability indices focus on point estimates, which may result in unreliable assessments of process performance. It is necessary to investigate their asymptotic correlationship among process capability indices $\hat{C}_p$, $\hat{C}_{pk}$ and $\hat{C}_{pm}$. In this paper, we study their asymptotic correlationship for some process capability indices $\hat{C}_p$, $\hat{C}_{pk}$ and $\hat{C}_{pm}$ under the normal process.

• Progress in Superconductivity and Cryogenics
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• v.14 no.2
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• pp.12-15
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• 2012

This paper presents simulation and small-scale experimental tests of a fault current controller. Smart fault controller as proposed and proven conceptually in our previous work is promising technology for the smart power grid where distributed and even stochastic generation sources are prevalent and grid operations are more dynamic. Existing protection schemes simply limiting the fault current to the pre-determined set values may not show best performance and even lead to coordination failures, potentially leading to catastrophic failure. Thus, this paper designs fault current controller with a full bridge thyristor rectifier, embedding a superconducting coil for which the controller is electrically invisible during normal operation because the loss due to the coil is near-zero. When a fault occurs and the resulting current through the superconducting coil exceeds a certain value set intelligently based on the current operating condition of the grid, the magnitude of the fault current is controlled to this desired value by adjusting the firing angles of thyristors such that the overall system integrity is successfully maintained. Detailed time-domain simulations are performed and lab-scale testing circuits are built to demonstrate the desired functionality and efficacy of the proposed fault current controller.

• Clinical and Experimental Pediatrics
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• v.58 no.3
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• pp.112-115
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• 2015

Hand, foot, and mouth disease (HFMD) is an acute, mostly self-limiting infection. Patients usually recover without any sequelae. However, a few cases are life threatening, especially those caused by enterovirus 71 (EV71). A 12-month-old boy was admitted to a primary hospital with high fever and vesicular lesions of the mouth, hands, and feet. After 3 days, he experienced 3 seizure episodes and was referred to our hospital. On admission, he was conscious and his chest radiograph was normal. However, 6 hours later, he suddenly lost consciousness and had developed a massive pulmonary hemorrhage that continued until his death. He experienced several more intermittent seizures, and diffuse infiltration of both lung fields was observed on chest radiography. Intravenous immunoglobulin, dexamethasone, cefotaxime, leukocyte-depleted red blood cells, fresh frozen plasma, inotropics, vitamin K, and endotracheal epinephrine were administered. The patient died 9 hours after intubation, within 3 days from fever onset. EV71 subgenotype C4a was isolated retrospectively from serum and nasopharyngeal swab by real-time reverse transcription-polymerase chain reaction. Here, we report a fatal case of EV71-associated HFMD with sudden-onset massive pulmonary hemorrhage and suspected encephalitis.

• Clinical and Experimental Pediatrics
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• v.45 no.12
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• pp.1546-1550
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• 2002

Purpose : The authors carried out this study to determine the relationship between vigabatrin (VGB) and visual field defect.. Methods : Seventy eight patients older than 8 years who had epilepsy which had developed and been diagnosed, and were receiving add-on therapy, were the subjects of this study. If suspicious results were obtained from the initial test with the Humphrey automatic perimeter, the patient was tested again with the Goldman perimeter. Follow-up examinations were performed on these patients after 6 months. Results : In this study, five of the 78 patients had suspicious primary test results, but upon the second examination they were all found to be normal. Thus there were no patients with visual field defects. Conclusion : VGB is a drug which may cause visual field defects, but in this study no patients presented with this symptom. Instead of limiting the use of VGB due to the adverse effect of visual field defect in the initial treatment of partial seizure and infantile spasm untreatable with other medication, if used with care it may not cause serious problems. Screening for visual defect is recommended, and in patients taking VGB regular examination is necessary.

• The Journal of Internal Korean Medicine
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• v.34 no.3
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• pp.298-311
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• 2013

Objectives : In this study, we aimed to investigate the effect of Eunhoebanchong-san (EBS) on caerulein-induced acute pancreatitis (AP) by detecting oxidative stress markers and performing histopathological examination. Methods : Thirty adult male Sprague-Dawley rats were divided into five groups as follows: normal (NOR), caerulein-induced (CON), caerulein+EBS (130 mg/kg, EA), caerulein+EBS (260 mg/kg, EB) and caerulein+EBS (520 mg/kg, EC) groups. Pancreatic tissues of rats from all groups were removed for apoptosis, and light, and electron microscopic examination. Blood of rats from all groups was obtained for oxidative stress markers and pathological examination. Pancreatic oxidative stress markers were evaluated by the measurements of serum amylase, and interleukin-6 (IL-6) levels were determined spectrophotometrically. Results : The ratio of pancreas/body weight increased significantly in the CON compared with the NOR, but decreased significantly in the EA, the EB, the EC groups compared with the CON. Caerulein administration resulted in a significant increase in amylase, but EBS reduced the levels of these enzymes. Interleukin-6 (IL-6) levels increased significantly in CON compared with NOR, but reduced in EA, EB, and EC group at 24 hrs. In the observations of optical microscopy and electron microscopy, the experimental groups showed significant decreases in pancreatic tissue inflammation, edema, vacuolization, necrosis compared to the control group. Altogether, this indicates EBS is potentially capable of limiting pancreatic damage produced during AP by restoring the fine structure of acinar cells and tissue. Conclusions : We concluded that EBS may have beneficial effects in the treatment of caerulein-induced AP.

• KSBB Journal
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• v.18 no.6
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• pp.517-521
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• 2003

Superoxide dismutase which is metalloenzyme that decomposes superoxide radicals into hydrogen peroxide and molecular oxygen. Vitreoscilla has FeSOD. Expression of FeSOD to paraquat was largely constitutive. This suggests that the basal level of FeSOD is sufficient to provide protection against superoxide generated during normal aerobic metabolism. Induction of SOD by iron supports that insertion of the active site metal into the corresponding apoprotein. The effect of paraquat on induction by iron seemed that iron brought the synergism effect in SOD activity with paraquat. It suggests that the relief of growth inhibition is due to protection against the lethality of O$_2$afforded by the elevated SOD. There may be control of FeSOD activity posttranslationally. Posttranslation control of enzyme function is particularly feasible for a metalloenzyme, for which conversion of apo- to holoenzyme may be the rate-limiting or regulatory step.