• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.4
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• pp.320-329
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• 2007

Electrokinesis and dielectrophoresis are important transport phenomena produced by external electric field applied to a microchannel containing a conductive fluid. We developed a CFD code to predict electrokinetic and dielectrophoretic flows in a microchannel with a uniform circular post array. Using the code, we calculated particle velocities driven by electrokinesis and dielectrophoresis, and conducted Monte Carlo simulations to visualize the particle motions. The code was validated by comparing the results with those from previous studies in literature. At a low electric field, electrokinesis and diffusion is the dominant transport mechanism. At a moderate electric field, dielectrophoresis is balanced with electrokinesis and diffusion, resulting in flowing filaments of particles in the microchannels. However, dielectrophoresis overwhelms the flow at a high electric field and traps particles locally. These results provide useful insight for optimizing design parameters of a microfluidic chip for biochemical analysis, especially for development of on-chip sample pretreatment techniques using electrokinetic and dielectrophoretic effects.

• Journal of Dental Anesthesia and Pain Medicine
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• v.22 no.5
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• pp.377-385
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• 2022

Background: Postoperative endodontic pain is an enigma for the dentist. This study aimed to evaluate the analgesic effect of 300 mg gabapentin or 75 mg pregabalin in reducing postoperative endodontic pain compared with a placebo. Methods: Ninety patients who needed root canal treatment with an initial numerical rating scale (NRS) pain score of > 4 (T0) were randomly divided into three groups (n=30). Patients were then administered either 300 mg gabapentin (group A), 75 mg pregabalin (group B), or a placebo (group C) 30 min prior to the start of endodontic treatment. A single operator performed single-visit endodontics, and pain was evaluated immediately after endodontic treatment (T1) and at 4 h (T2), 8 h (T3), 12 h (T4), 24 h (T5), 48 h (T6), and 72 h (T7) using the NRS. Ibuprofen/paracetamol (400 mg/325 mg) was administered as a rescue dose if needed. Results: Pregabalin performed significantly better when compared with gabapentin at all time points except at 72 h after treatment (P=0.170). The placebo group showed significantly higher pain scores than the other two groups. The percentage of pain relief was maximum for pregabalin (92.1%), followed by gabapentin (87.6%) and placebo (69.1%) at 72 h after treatment completion. Conclusion: This study showed that pretreatment with a single dose of pregabalin and gabapentin both had greater analgesic effects than a placebo. They can be effectively used to reduce postoperative endodontic pain.

• Nuclear Engineering and Technology
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• v.45 no.4
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• pp.529-538
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• 2013

Scattered photons cause blurring and distortions in flash radiography, reducing the accuracy of image reconstruction significantly. The effect of the scattered photons is taken into account and an iterative deduction of the scattered photons is proposed to amend the scattering effect for image restoration. In order to deduct the scattering contribution, the flux of scattered photons is estimated as the sum of two components. The single scattered component is calculated accurately together with the uncollided flux along the characteristic ray, while the multiple scattered component is evaluated using correction coefficients pre-obtained from Monte Carlo simulations.The arbitrary geometry pretreatment and ray tracing are carried out based on the customization of AutoCAD. With the above model, an Iterative Procedure for image restORation code, IPOR, is developed. Numerical results demonstrate that the IPOR code is much more accurate than the direct reconstruction solution without scattering correction and it has a very high computational efficiency.

• Radiation Oncology Journal
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• v.13 no.1
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• pp.87-94
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• 1995

Since March 1992, total 200 patients who visited our hospital as functional or organic lesions of central nervous system were treated by gamma knife stereotactic radiosurgery for 27 months. Thirty-nine patients of total cases was diagnosed as cerebral arteriovenous malformation. The rate of magnification on X-ray film was reduced by cutting fixation adaptor from 1.0 to below 1.45 times. In order to treat the deep- and lateral-seated cerebral arteriovenous malformation, we slightly modified the angiographic indicator, the commercial Leksell system, by cutting each inner sides about 5mm, We performed the more distinction of the scales by adapting 0.5mm or 1mm copper filter to angiographic indicator. The center point of indicator(X=100mm, Y=100mm, Z=100mm) is corrected by adjusting scales of X-, Y-, Z-axis to each inner 100 and outer 100 point within 1-2mm by repeated exposure of X-ray on films in trial-and-errors. We have developed the 'GKANGIO' programed as the Fortran-77 in Microvax - 3100, which can save treatment planning time and perform accurate pretreatment planning using the theoretical target metrix center. The theoretical description of the simplified method is presented for the reduction of experimental and numerical errors in treatment planning of radiosurgery.

• Journal of Oral Medicine and Pain
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• v.39 no.3
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• pp.96-99
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• 2014

Purpose: The objective of this retrospective pilot study was to evaluate the effectiveness of Gabapentin in patients with primary burning mouth syndrome (BMS). Methods: Ten subjects were diagnosed with primary BMS (8 women and 2 men). The mean age was 60.1 years. They had clinical examination to exclude local factors such as the presence of Candida species, xerostomia, lichen planus, etc. They also underwent hematological examination to exclude secondary BMS due to systemic disorders. Pain was assessed by patients on an 11-point numerical rating score system (0 to 10). Gabapentin was administered at a starting dose of 300 mg/day, slowly titrated up to maximum of 1,800 mg/day. All patients were treated for 4 weeks. Results: One half of the patients (n=5) obtained reduction in pain over the treatment period. Four patients reported no reduction in pain symptoms. One patient reported that symptoms were worsening. The average pain score before the treatment was 6.3 and after the treatment was 5.25. No significant relationship was detected between pretreatment and posttreatment pain score. Only one patient noted mild side effect (dizziness). Conclusions: This retrospective pilot study provides no preliminary evidence that Gabapentin has effect in the management of BMS. However, further research (well-designed, randomized, and controlled trial with large sample) would be needed to investigate the efficacy of Gabapentin in treatment of BMS.

• The Korean Journal of Pain
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• v.36 no.2
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• pp.195-207
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• 2023

Background: This study aimed to compare the effectiveness of the pericapsular nerve group (PENG) block and intra-articular injection (IAI) of steroid-bupivacaine in the treatment of hip osteoarthritis (OA). Methods: After randomization, patients received either a PENG block or IAI under ultrasound-guidance. Clinical evaluations were recorded at baseline, day 1, and weeks 1, 4, and 8 post-intervention. The numerical rating scale (NRS), Western Ontario and McMaster Universities Arthritis Index (WOMAC), Harris Hip Scale (HHS) scores, pain medication use determined by a quantitative analgesic questionnaire, and patient satisfaction were evaluated. Results: Sixty patients were included in this study. NRS scores improved significantly for both groups during the follow-up compared to pretreatment (P < 0.001), with better pain scores for the PENG group (P < 0.001) at day 1 with larger effect size (Cohen's d = 4.62), and IAI group at 4 (Cohen's d = 5.15) and 8 (Cohen's d = 4.33) weeks (P < 0.001). There was no significant difference in pain medication consumption (P = 0.499) and patient satisfaction (P = 0.138) between groups. Patients in the IAI group experienced significant improvement in HHS (Cohen's d = 2.16, P = 0.007) and WOMAC (Cohen's d = 1.02, P = 0.036) scores at 8 weeks compared to the PENG group. Conclusions: The ultrasound-guided PENG block provides effective pain relief which improves functionality and quality of life in hip OA patients up to 2 months. The PENG block can be considered an easy, safe, and useful alternative treatment modality for hip OA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.95-101
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• 2017

In this paper, the sizing removal condition for the pretreatment of composite materials is obtained numerically by applying an image processing algorithm and nickel-plated carbon fiber is fabricated by a dry process method to enhance its electromagnetic shielding performance. Sizings that are wrapped in a polymer type material during the manufacturing of carbon fiber should be removed for dry coating. A numerical value, that is the correlation, can be obtained by determining the regular pattern of the carbon fiber in the image taken by a scanning electron microscope (SEM) after the sizing is removed. The application of the proposed numerical method to the SEM image of the fiber after the sizing is removed with solution, compressed air, solution and compressed air (hybrid), showed that this method of eliminating the sizing is superior to the hybrid method. Then, by spreading the carbon fiber roll with the sizing removed, we were able to produce nickel plated carbon fiber by the roll-to-roll sputtering method. The electromagnetic shielding performance of the fabricated 30, 40 and 100 nickel coated carbon fibers was measured. The Korea Advanced Institute of Science and Technology evaluated the electromagnetic shielding performance of the 100 nickel-coated carbon fiber to have a maximum value of 73.2 (dB) and a minimum value of 66.7 (dB). This is similar to the electromagnetic shielding rate of copper and shows that this material can be used as a cable for EV / HEV automobiles.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.526-531
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• 2010

For efficient use of wood, it is important to control moisture of wood in processing wood. Near-infrared (NIR) spectroscopy can be used to estimate the physical and chemical properties of materials quickly and nondestructively. In this study, it was intended to measure the moisture contents on the surface of wood using NIR spectroscopy coupled with multivariate analytic statistical techniques. Because NIR spectroscopy is affected by the chemical components of the specimens and contains signal noise, a regression model for detecting moisture content of wood was established after carrying out several numerical pretreatments such as Smoothing, Derivative and Normalization in this study. It shows that the regression model using NIR absorbance in the range of 750~2,500 nm predicts the actual surface moisture content very well. Near-infrared spectroscopy technique developed in this study is expected to improve a technology to control moisture content of wood in using and drying process.