• Nuclear Engineering and Technology
• /
• v.47 no.4
• /
• pp.479-487
• /
• 2015

The thallium-doped sodium iodide [NaI(Tl)] scintillation detector is preferred as a gamma spectrometer in many fields because of its general advantages. A silicon photomultiplier (SiPM) has recently been developed and its application area has been expanded as an alternative to photomultiplier tubes (PMTs). It has merits such as a low operating voltage, compact size, cheap production cost, and magnetic resonance compatibility. In this study, an array of SiPMs is used to develop an NaI(Tl) gamma spectrometer. To maintain detection efficiency, a commercial NaI(Tl) $2^{\prime}{\times}2^{\prime}$ scintillator is used, and a light guide is used for the transport and collection of generated photons from the scintillator to the SiPMs without loss. The test light guides were fabricated with polymethyl methacrylate and reflective materials. The gamma spectrometer systems were set up and included light guides. Through a series of measurements, the characteristics of the light guides and the proposed gamma spectrometer were evaluated. Simulation of the light collection was accomplished using the DETECT 97 code (A. Levin, E. Hoskinson, and C. Moison, University of Michigan, USA) to analyze the measurement results. The system, which included SiPMs and the light guide, achieved 14.11% full width at half maximum energy resolution at 662 keV.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1173-1177
• /
• 2004

The high investment is necessary for the new high speed lines. So the KRRI was interested in the possibility of upgrading the existing line in order to speed up the train in the conventional lines. The tilting train system has been developed because the reconstruction of railway for the cant compensation costs very high. The purpose of the tilting system is to compensate the centrifugal acceleration in order to reduce the lateral acceleration of the passenger at high speed on the curves.The pantograph of the tilting train is indispensable in order to supply the electrification equipments with power in safe. The dynamic interaction between the pantograph and the overhead catenary system causes the variation of the contact force and the contact force variation can cause contact losses, arcing and sparking. If the spark happens between the pantograph and the overhead catenary system, the EMI(electro magnetic interface) and noises may occur. After all, the quality of current collection is deteriorated. This paper deals with the active control of pantograph and presents the LQ-servo controller to reduce the contact force variation.

• Journal of the Korean Society for Railway
• /
• v.8 no.4
• /
• pp.361-366
• /
• 2005

The high investment is necessary for the new high speed lines. So the KRRI has been interested in the possibility of upgrading the existing line in order to speed up the train in the conventional lines. The pantograph in train is indispensable in order to supply the electrification equipments with power in safe. The pantograph and the overhead wire form a dynamic coupled system and they affect each other through the contact force. Unfortunately, as the operational speed of a train increases, the vibration of the pantograph and the overhead wire also increases. This may lead to a zero contact force between the pantograph head and the overhead wire, which can results in the loss of contact, arching and abrasion. If the arching and spark happen between the pantograph and the overhead catenary system, the EMI(electro magnetic interface) and noises may occur. After all, the quality of current collection is deteriorated. This paper describes the dynamic response between the pantograph and catenary system by the numerical simulations and presents the LQ-servo controller to reduce the contact force variation

• Resources Recycling
• /
• v.9 no.2
• /
• pp.3-10
• /
• 2000

Used aluminum beverage can(UBC) is an important secondary resource. Domestic recycling rate of UBC should be increased from the standpoint of resource savings and environmental protection. Aluminum can to can recycling is divided into two steps. The first step was composed of the processes such as collection of used beverage cans, shredding, magnetic separation, de-lacquring, melting and casting. The second is remelting and casting, heat treatment, hot and cold rolling, annealing, and can making. With brief discussion about this recycling technology, this article covers aluminum can consumption, the present state of aluminum can recycling in Korea, Japan, USA, and Europe.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.535-544
• /
• 2008

Unlike MS(Magnetic Stripe), SMART CARD is equipped with COS(Chip Operating System) consisting of the Microprocessor and Memory where information can be stored and processed, and there are two types of cards according to the contact mode; the contact type that passes through a gold plated area and the contactless one that goes through the radio-frequency using an antenna embedded in the plastic card. the contactless IC card used for the transportation card was first introduced into local area buses in Seoul, and expanded throughout the country so that it has removed the inconvenience such as possession of cash, fare payment and collection. Focusing on the Seoul metropolitan area in 2004, prepaid and pay later cards were adopted and have been used interchangeably between a bus and subway. The card terminal compatible between a bus and subway is Proximity Integrated Circuit Card(PICC) as international standards(1443 Type A,B), communicates in the 13.56MHz dynamic frequency modulation-demodulation system, and adopts the Multi Secure Application Module(SAM). In the second half of 2009, the system avaliable nationwide will be built when the payment SAM standard is implemented.

• Journal of Korean Neurosurgical Society
• /
• v.44 no.5
• /
• pp.334-337
• /
• 2008

Spinal intradural extramedullary teratoma is a rare condition that develops more commonly in children than in adults and may be associated with spinal dysraphism. We report a rare case of adult-onset intradural extramedullary teratoma in the thoracolumbar spinal cord with no evidence of spinal dysraphism and without the history of prior spinal surgery. The patient was a 38-year-old male whose chief complaint was urinary incontinence. X-ray images of the thoracolumbar spine showed the widening of the interpedicular distance and posterior marginal erosion of the vertebral bodies and pedicles at the T11, T12, and L1 level. Magnetic resonance imagings of the lumbar spine showed a lobulated inhomogeneous high signal intradural mass ($87{\times}29{\times}20mm$) between T11 and L1 and a high signal fluid collection at the T11 level. Laminectomy of the T11- L1 region was performed, and the mass was subtotally excised. The resected tumor was histopathologically diagnosed as a mature cystic teratoma. The patient's symptom of urinary incontinence was improved following the surgery.

• Journal of Oral Medicine and Pain
• /
• v.44 no.3
• /
• pp.127-132
• /
• 2019

Septic arthritis of the temporomandibular joint (TMJ) is an uncommon disease caused by microbial pathogens through hematogenous infection, local spread, or iatrogenic infection. As the symptoms have an insidious onset, the early stage of septic arthritis is often confused with other diseases. A 49-year-old man was referred for increasing preauricular pain, swelling, and restricted mouth opening. He had been initially diagnosed as having a conventional temporomandibular joint disorder and trigeminal neuralgia and had been treated for the same. Imaging studies including panoramic view, lateral tomography, computed tomography with contrast enhancement, and magnetic resonance imaging were performed. Erosive bone change with displacement of the involved condyle, diffuse swelling of adjacent soft tissue, and fluid collection in the joint space were noted. Needle aspiration of the joint space and bacterial culture confirmed the diagnosis of septic arthritis of the TMJ and he was treated with antibiotic therapy and surgical drainage. Clinicians should always consider the diagnosis of septic arthritis of the TMJ in patients with preauricular pain or swelling.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.1
• /
• pp.103-109
• /
• 2021

Fine chips generated by machining have an impact on machine failure and quality of machined products, it is necessary to remove the chips, so the microchip collection and removal device by rotating conveyor belt with neodymium permanent magnets was developed. In this research, to solve the problem for reducing the existing microchips in the tank, a micro-chip removal device by rotating conveyor belt with neodymium permanent magnets developed. In the development of micro-chip removal device, 3D CATIA modeling was used, and the flow analysis and the electromagnetic force analysis were performed with COMSOL Multiphysics program. To evaluate the performance of the prototypes produced, design of experiments (DOE) is used to obtain the effect of neodymium conveyor movement speed on chip removal for the ANOVA analysis of recovered powders. An experiment was conducted to investigate the effect of the conveyor feed rate on the chip removal performance in detail. As a result of the experiment, it was confirmed that the slower the feeding speed of the fine chip removing device, the more efficient the chip removal.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.12
• /
• pp.4816-4834
• /
• 2020

This paper proposes transfer learning and fine-tuning techniques for a deep learning model to detect three distinct brain tumors from Magnetic Resonance Imaging (MRI) scans. In this work, the recent YOLOv4 model trained using a collection of 3064 T1-weighted Contrast-Enhanced (CE)-MRI scans that were pre-processed and labeled for the task. This work trained with the partial 29-layer YOLOv4-Tiny and fine-tuned to work optimally and run efficiently in most platforms with reliable performance. With the help of transfer learning, the model had initial leverage to train faster with pre-trained weights from the COCO dataset, generating a robust set of features required for brain tumor detection. The results yielded the highest mean average precision of 93.14%, a 90.34% precision, 88.58% recall, and 89.45% F1-Score outperforming other previous versions of the YOLO detection models and other studies that used bounding box detections for the same task like Faster R-CNN. As concluded, the YOLOv4-Tiny can work efficiently to detect brain tumors automatically at a rapid phase with the help of proper fine-tuning and transfer learning. This work contributes mainly to assist medical experts in the diagnostic process of brain tumors.

• Journal of Korean Neurosurgical Society
• /
• v.66 no.5
• /
• pp.552-561
• /
• 2023

Objective : A chronic subdural hematoma (CSDH) is a collection of bloody fluid located in the subdural space and encapsulated by neo-membranes. An inner subdural hygroma (ISH) is observed between the inner membrane of a CSDH and the brain surface. We present six cases of CSDH combined with ISH treated via endoscopy. Methods : Between 2011 and 2022, among the 107 patients diagnosed with CSDH in our institute, six patients were identified as presenting with CSDH combined with ISH and were included in this study. Preoperative computerized tomography (CT) and magnetic resonance imaging (MRI) were performed simultaneously, and endoscopic surgery for aspiration of the hematoma was performed in all cases of CSDH combined with ISH. Results : The mean age of patients was 71 years (range, 66 to 79). The patients were all male. In two cases, the ISH was not identified on CT, but was clearly seen on MRI in all patients. The inner membrane of the CSDH was tense and bulging after draining of the CSDH in endoscopic view due to the high pressure of the ISH. After fenestration of the inner membrane of the CSDH and aspiration of the ISH, the membrane was sunken down due to the decreasing pressure of the ISH. There was one recurrence in post-operative 2-month follow up. The symptoms improved in all patients after surgery, and there were no surgery-related complications. Conclusion : CSDH combined with ISH can be diagnosed on imaging, and endoscopic surgery facilitates safe and effective treatment.