• Journal of Magnetics
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• v.18 no.3
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• pp.326-330
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• 2013

Magnetic treatment of surface vessels and submarines (Deperm) is required to camouflage them against magnetic detection from enemy marine force. So far, deperm has been accomplished by applying an alternating magnetic field of which amplitude decreases linearly. However, the reduction of the residual flux density in the direction of magnetic field is not linear in the case of the linear protocol, since the ferromagnetic material used to construct a surface vessel, mainly Fe-C, shows a nonlinear behavior in an alternating magnetic field. This is one of main reasons to make an ordinary deperm protocol inefficient. In this paper, we propose the exponential deperming protocol and compare the exponential protocol to conventional linear protocol within the framework of deperm performance. We found out that step number could be reduced in the exponential protocol compare with in the linear protocol, because the larger numbers of deperm steps are dedicated in the irreversible domain process region on the magnetic hysteresis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1693-1699
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• 2011

In this paper, for magnetic silence technology of naval vessel, is to make lab deperm system and to evaluate the deperm capacity of naval vessel regarding deperm protocol. Initial permanent magnetic field of naval vessel is magnetized before deperm, having the magnetic field of the same size, to evaluate the deperm capacity regarding a variety of deperm protocol for experimental reliability growth. Current dead time effect of deperm protocol is measured at the different initial current, which are 8A, 6A and 4A respectively. Furthermore, the experiment under the same condition except changing duty cycle into 50% is carried out. As a result, it is possible to compare the six different experiment outcomes. The result shows that the experiment with dead time improve the deperm capacity more than 48.51 percent comparing to the case without dead time.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.2
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• pp.136-142
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• 2006

Temporomandibular joint(TMJ) disorders have characteristic clinical findings such as pain, joint sound, and abnormal jaw function. With the rapid progress in TMJ imaging techniques, magnetic resonance imaging(MRI) especially provides the clinician and researcher with the ability to evaluate TMJ disorders(effusion, anterior disk displacement) and the hard and soft tissue of the TMJ. In order to manage the internal derangement of TMJ such as anterior disk displacement, the so-called appliance therapy is commonly used. This technique became the treatment of choice before surgical intervention by many practitioners. The purpose of the present study was to evaluate and determine the efficacy of anterior repositioning splint by means of the change of the position of the disk through pre- and post-treatment MRI. MRI and clinical symptom were carefully recorded in TMJ disorder patients. The relationship between TMJ symptoms such as pain, clicking sound, and disk displacement and effusion in MRI were analyzed. Then, splint therapy was applied for 3 months according to our protocol; at day 1, patients should wear 24 hours, in order to accomodate the splint and then, wearing time is reduced to 12 hours per day for one month. During next 2 months, it is tapered to 8 hours per day according to the evaluation of the clinical symptoms. Post-treatment MRI was obtained after 3 month protocol. This treatment strategy improved the clinical symptoms of TMJ disorder, and effusion and articular disk position showed a significant change. In conclusion, a treatment modality using an anterior repositioning splint therapy is an appropriate method for temporomandibular disorder patients.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.98-98
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• 2003

We will present various MR findings of hyperacute ischemic stroke with our own experiences in the management of the patients according to the findings. 대상 및 방법： A total of 441 patients were underwent 'acute stroke MR' imaging protocol between Mar. 2001 and Jun. 2003. The protocol included initial T2-weighted image (WI), diffusion WI (DWI, b=2000), time-of-flight (TOF) MR angiography (MRA), and pefusion WI(PWI), and follow-up T2WI, DWI, TOF MRA, and neck vessel contrast-enhanced MRA obtained three to five days after the insult. Among them, we retrospectively reviewed the MR findings and clinical courses of 193 patients with anterior circulation territorial infarction. Those ICA and MCA lesions were divided into six and five groups respectively according to the level and mechanism of the occlusion. PWI findings can be another factor in the management planning.

• Journal of Korean Neurosurgical Society
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• v.47 no.1
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• pp.51-54
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• 2010

Surgery has a key role in the treatment of malignant peripheral nerve sheath tumors (MPNSTs), but the resectability of paraspinal MPNSTs is only 20%. Therefore, spinal MPNSTs show frequent recurrence and poor prognosis. Local recurrence is much more common than metastasis for MPNSTs, and surgery still has a key role in the treatment of local recurrence. Therefore, it is important that recurrence must be detected before resectability is lost. However, no evidence-based follow-up protocol has been established for MPNST. The authors performed gross total resection in a 34-year-old woman presented with thoracic MPNST. Adjuvant radiotherapy and chemotherapy were not administered since these adjuvant therapies generally do not improve survival in MPNST and may cause additional neurovascular damage. Instead, the authors monitored the primary site every 3 months using magnetic resonance imaging to detect local recurrence at the earliest opportunity. The tumor recurred locally on two occasions without overt symptoms at 21 and 24 months postoperatively. These recurrences were treated successfully by gross total removal.

• Archives of Craniofacial Surgery
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• v.20 no.6
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• pp.354-360
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• 2019

Background: Keloids are benign fibro-proliferative lesion, related to excessive inflammatory reactions in certain anatomical areas, including the auricles. Their specific etiology remains unclear; nonetheless they exhibit tumor-like characteristics of significant recurrence and cause emotional distress, even with various treatment strategies. We applied intermittent magnetic pressure therapy on ear keloids in combination with surgical excision, and present its effectiveness herein. Methods: Ear keloid patients were treated with surgical excision followed by magnetic pressure therapy. The keloid tissues underwent excision and keloid marginal flaps were utilized for wound closure. Intermittent magnetic pressure therapy was applied 2 weeks after the surgical procedure. The pressure therapy consisted of a 3-hour application and 2-hour resting protocol (9 hr/day), and lasted for 6 months. The results were analyzed 6 months after the therapeutic procedures, using the scar assessment scale. Results: Twenty-two ear keloids from 20 patients were finally reviewed. Among the keloids that completed the therapeutic course, 20 ear keloids out of 22 in total (90.9%) were successfully eradicated. Two patients (2 keloids) exhibited slight under-correction. Postoperative complications such as wound dehiscence or surgical site infection were not noted. The scar assessment scale demonstrated a significant improvement in each index. The intermittent pressure therapy led to patient compliance, and avoided pressure-related pain and discomfort. Conclusion: Excision followed by intermittent pressure application using a magnet successfully reduced the burden of fibro-proliferative keloids, and had good patient compliance. The role of intermittent pressure application and resting should be studied with regard to keloid tissue remodeling.

• Korean Journal of Radiology
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• v.25 no.8
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• pp.726-741
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• 2024

Recent advancements in Alzheimer's disease treatment have focused on the elimination of amyloid-beta (Aβ) plaque, a hallmark of the disease. Monoclonal antibodies such as lecanemab and donanemab can alter disease progression by binding to different forms of Aβ aggregates. However, these treatments raise concerns about adverse effects, particularly amyloid-related imaging abnormalities (ARIA). Careful assessment of safety, especially regarding ARIA, is crucial. ARIA results from treatment-related disruption of vascular integrity and increased vascular permeability, leading to the leakage of proteinaceous fluid (ARIA-E) and heme products (ARIA-H). ARIA-E indicates treatment-induced edema or sulcal effusion, while ARIA-H indicates treatment-induced microhemorrhage or superficial siderosis. The minimum recommended magnetic resonance imaging sequences for ARIA assessment are T2-FLAIR, T2^* gradient echo (GRE), and diffusion-weighted imaging (DWI). T2-FLAIR and T2^* GRE are necessary to detect ARIA-E and ARIA-H, respectively. DWI plays a role in differentiating ARIA-E from acute to subacute infarcts. Physicians, including radiologists, must be familiar with the imaging features of ARIA, the appropriate imaging protocol for the ARIA workup, and the reporting of findings in clinical practice. This review aims to describe the clinical and imaging features of ARIA and suggest points for the timely detection and monitoring of ARIA in clinical practice.

• The Journal of Internal Korean Medicine
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• v.44 no.3
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• pp.562-577
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• 2023

Objectives: This is a five-year survival and complete response (CR) report on pancreatic cancer treated with western medicine and Korean traditional medicine. Method: A 59-year-old woman diagnosed with pancreatic cancer visited ○○ Korean traditional medicine hospital after neoadjuvant chemotherapy and pylorus-preserving pancreaticoduodenectomy. She was treated with Korean traditional medicine, including acupuncture, abdominal moxibustion, wild ginseng pharmacopuncture, and herbal medicine, which was based on integrated medicine therapy (IMT), from March 2018 to September 2022. The tumor size was measured by scanning with computed tomography (CT), magnetic resonance imaging, and positron-emission tomography/CT. Adverse events were evaluated using laboratory conclusion and National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. Result: During four years and three months of treatment, IMT maintained safety. The patient finally reached five-year survival without any recurrence or complication (CR) on October 26, 2022. Conclusion: We suggest that an integrative approach including Korean traditional medicine can be a meaningful treatment option for pancreatic cancer. Further studies should be performed to establish the proper treatment protocol of integrative medicine for pancreatic cancer.

• Progress in Medical Physics
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• v.28 no.4
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• pp.190-196
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• 2017

For the $ViewRay^{(R)}$ system (ViewRay Inc., Cleveland, OH, USA) which is representative of magnetic resonance (MR) guided radiotherapy machine, it is important to evaluate effectiveness of AAPM's TG-51 protocol and the effect of the magnetic field on absolute dosimetry. In order to measure the absolute dose, MR-compatible chamber and water phantom system manufactured in this study were used. The materials of the water phantom system were plastic of polymethyl methacrylate (PMMA) and non-ferrous materials. Due to the inherent feature of the $ViewRay^{(R)}$, all Co-60 sources are not located at gantry angle of $0^{\circ}$ while being located at gantry angle of $90^{\circ}$. For this reason, absolute dosimetry was performed based on the measurements in solid water phantom (SWP) and water which determine the SWP to water correction factor. For evaluation of output constancy with gantry angle, measurements were made with ionization chamber inserted in cylindrical water-equivalent phantom. For measured doses in water, the values of dose deviation according to a reference dose of 200 cGy for Head 1, Head 2 and Head 3 were -0.27%, -0.45% and -0.22%, respectively. For measured doses in SWP, the values of dose deviation according to a reference dose of 200 cGy for Head 1, Head 2 and Head 3 were -1.91%, -2.07% and -1.84%, respectively. All values of dose measured in SWP tended to be less than those measured in water by -1.63%. With the reference gantry angles of $0^{\circ}$ and $90^{\circ}$, the maximum values of deviation for Head 1, Head 2 and Head 3 were 0.48%, 1.06% and 0.40%, respectively. The measurement agreement is within the range of results obtainable for conventional treatment machines. The low strength of the magnetic field does not affect dose measurements. Using the SWP to water correction factor, absolute doses for $ViewRay^{(R)}$ system can be measured.

• Journal of Korean Neurosurgical Society
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• v.45 no.1
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• pp.39-42
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• 2009

We report a supratentorial primitive neuroectodermal tumor (sPNET) in 17-year-old primipara in the second trimester her pregnancy. Magnetic resonance imaging revealed a left frontoparietal mass with solid and cystic component. Gross-total resection was achieved via a left frontoparietal craniotomy. It was decided to suspend the radiotherapy and chemotherapy until the 30 weeks of gestation. But, a sudden uncal herniation was developed due to the reccurrence of the tumor and bleeding into the tumor at the 25 weeks of gestation and the patient died after urgent decompressive surgery. sPNETs is an extremely rare brain tumor in pregnancy and only two cases were reported in the literature to date. There is no universally agreed treatment protocol for sPNETs during pregnancy and a multidisciplinary approach is required in treatment. In the present study, the clinical, histopathological features and therapeutical difficulties of sPNETs diagnosed during pregnancy was discussed with the literature review.