18 results on '"Dong Woo Park"'
Search Results
2. Microbleeds in the Corpus Callosum in Anoxic Brain Injury
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Chang Su Kim, Dong Woo Park, Tae Yoon Kim, Young-Jun Lee, and Ji Young Lee
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anoxic brain damage ,brain hemorrhage ,corpus callosum ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
Purpose This study was performed to evaluate the relationship between callosal microbleeds and anoxic brain injury. Materials and Methods Twenty-seven patients with anoxic brain injuries were analyzed and retrospectively compared to the control group of patients without a history of anoxic brain injury using Fisher’s exact test regarding comorbidities and cerebral microbleeds. The patient group was subdivided according to the presence of callosal microbleeds. Fisher’s exact test was used to compare the presence of typical MRI findings of anoxic brain injury, use of cardiopulmonary resuscitation, and prognosis. The Mann-Whitney U test was used to compare the interval between the occurrence of anoxic brain injury to MRI acquisition. Results The prevalence of cerebral microbleeds in the patient group was 29.6%, which was significantly higher than that in the control group at 3.7% (p = 0.012). All cerebral microbleeds in the patient group were in the corpus callosum. Compared with the callosal microbleed-absent group, the callosal microbleed-present group showed a tendency of good prognosis (6/8 vs. 11/19), fewer typical MRI findings of anoxic brain injury (2/8 vs. 10/19), and more cardiopulmonary resuscitation (6/8 vs. 12/19), although these differences did not reach statistical significance (p = 0.35, p = 0.19, and p = 0.45, respectively). Conclusion Callosal microbleeds may be an adjunctive MRI marker for anoxic brain injury.
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- 2020
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3. Design of Novel Tricaprylin-Incorporated Multi-Layered Liposomal System for Skin Delivery of Ascorbic Acid with Improved Chemical Stability
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Myoung Jin Ho, Dong Woo Park, and Myung Joo Kang
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ascorbic acid ,lipo-oil-some ,skin delivery ,tricaprylin ,photostability ,topical application ,Medicine ,Pharmacy and materia medica ,RS1-441 - Abstract
L-ascorbic acid (Vit C) possesses a variety of dermatological functions in maintaining skin health and anti-aging properties. However, its topical application is challenging owing to its liability to light, oxygen, or heat. Therefore, in this study, a novel liposomal system, including a lipophilic neutral oil named a lipo-oil-some (LOS), was designed to improve the chemical stability and aid the skin absorption of Vit C. The vesicular systems were prepared using the ethanol injection method, employing phosphatidylcholine, cholesterol, dipalmitoyl-sn-glycerol-3-phosphoglycerol, and tricaprylin as neutral oil. The optimized LOS was characterized as follows: shape, multi-layered sphere; size, 981 nm; zeta potential, −58 mV; and Vit C encapsulation efficiency, 35%. The encapsulation of the labile compound into the novel system markedly enhanced photostability, providing over 10% higher Vit C remaining compared to Vit C solution or Vit C-loaded conventional liposome under a light intensity of 20,000 lx. On the other hand, the ex vivo skin permeation and accumulation of Vit C with the LOS system were comparable to those of smaller conventional liposomes (198 nm) in a Franz diffusion cell model mounted with porcine skin. Based on these findings, we concluded that the novel liposomal system could be utilized for skin delivery of Vit C with enhanced chemical stability.
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- 2023
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4. Respiratory syncytial virus-associated seizures in Korean children, 2011–2016
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Teahyen Cha, Young Jin Choi, Jae-Won Oh, Chang-Ryul Kim, Dong Woo Park, In Joon Seol, and Jin-Hwa Moon
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Respiratory syncytial virus ,Child ,Seizure ,Magnetic resonance imaging ,Pediatrics ,RJ1-570 - Abstract
Purpose Respiratory syncytial virus (RSV) infection can cause various neurological complications. This study aimed to investigate the RSV-associated neurologic manifestations that present with seizures. Methods We retrospectively reviewed the medical records of patients aged less than 15 years with laboratory-confirmed RSV infections and seizures between January 2011 and December 2016 in a regional hospital in South Korea. Results During this period, 1,193 patients with laboratory-confirmed RSV infection were identified. Of these, 35 (35 of 1,193, 2.93%; boys, 19; girls, 16; mean age: 20.8±16.6 months) presented with seizures. Febrile seizure was the most common diagnosis (27 of 35, 77.1%); simple febrile seizures in 13 patients (13 of 27, 48.1%) and complex febrile seizures in 14 (14 of 27, 51.9%). Afebrile seizures without meningitis or encephalopathy were observed in 5 patients (5 of 35, 14.3%), seizures with meningitis in 2 (2 of 35, 5.7%), and seizure with encephalopathy in 1 (1 of 35, 2.9%) patient. Lower respiratory symptoms were not observed in 8 patients. In a patient with encephalopathy, brain diffusion-weighted magnetic resonance imaging revealed transient changes in white matter, suggesting cytotoxic edema as the mechanism underlying encephalopathy. Most patients recovered with general management, and progression to epilepsy was noted in only 1 patient. Conclusion Although febrile seizure are the most common type of seizure associated with RSV infection, the proportion of patients with complex febrile seizures was higher than that of those with general febrile seizures. Transient cytotoxic edema may be a pathogenic mechanism in RSV-related encephalopathy with seizures.
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- 2019
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5. Diffusion Tensor Imaging and Quantitative Magnetic Resonance Volumetric Assessment in the Diagnosis of Hemimegalencephaly: A Case Report
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Seung-Jin Yoo, Ji Young Lee, Young-Jun Lee, Dong Woo Park, Tae-Yoon Kim, and Hee-Jin Kim
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diffusion tensor imaging ,hemimegalencephaly ,magnetic resonance imaging ,seizure ,image processing ,computer-assisted ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
A 27-year-old female presented with repeated seizures. As the left frontal lobe volume was enlarged in comparison with the right frontal lobe, hemimegalencephaly was suggested. Abnormal white matter fiber tracts running from the left frontal lobe to the fornix and hippocampus were found on diffusion tensor imaging (DTI). We performed quantitative measurements of brain volume and confirmed hemimegalencephaly. DTI and MRI-based volumetry techniques could be useful to objectively diagnose hemimegalencephaly.
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- 2019
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6. CT texture analysis of tonsil cancer: Discrimination from normal palatine tonsils
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Tae-Yoon Kim, Ji Young Lee, Young-Jun Lee, Dong Woo Park, Kyung Tae, and Yun Young Choi
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Medicine ,Science - Abstract
The purposes of the study were to determine whether there are differences in texture analysis parameters between tonsil cancers and normal tonsils, and to correlate texture analysis with 18F-FDG PET/CT to investigate the relationship between texture analysis and metabolic parameters. Sixty-four patients with squamous cell carcinoma of the palatine tonsil were included. A ROI was drawn, including all slices, to involve the entire tumor. The contralateral normal tonsil was used for comparison with the tumors. Texture analysis parameters, mean, standard deviation (SD), entropy, mean positive pixels, skewness, and kurtosis were obtained using commercially available software. Parameters were compared between the tumor and the normal palatine tonsils. Comparisons were also performed among early tonsil cancer, advanced tonsil cancer, and normal tonsils. An ROC curve analysis was performed to assess discrimination of tumor from normal tonsils. Correlation between texture analysis and 18F-FDG PET/CT was performed. Compared to normal tonsils, the tumors showed a significantly lower mean, higher SD, higher entropy, lower skewness, and higher kurtosis on most filters (p
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- 2021
7. CT texture analysis of tonsil cancer: Discrimination from normal palatine tonsils.
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Tae-Yoon Kim, Ji Young Lee, Young-Jun Lee, Dong Woo Park, Kyung Tae, and Yun Young Choi
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Medicine ,Science - Abstract
The purposes of the study were to determine whether there are differences in texture analysis parameters between tonsil cancers and normal tonsils, and to correlate texture analysis with 18F-FDG PET/CT to investigate the relationship between texture analysis and metabolic parameters. Sixty-four patients with squamous cell carcinoma of the palatine tonsil were included. A ROI was drawn, including all slices, to involve the entire tumor. The contralateral normal tonsil was used for comparison with the tumors. Texture analysis parameters, mean, standard deviation (SD), entropy, mean positive pixels, skewness, and kurtosis were obtained using commercially available software. Parameters were compared between the tumor and the normal palatine tonsils. Comparisons were also performed among early tonsil cancer, advanced tonsil cancer, and normal tonsils. An ROC curve analysis was performed to assess discrimination of tumor from normal tonsils. Correlation between texture analysis and 18F-FDG PET/CT was performed. Compared to normal tonsils, the tumors showed a significantly lower mean, higher SD, higher entropy, lower skewness, and higher kurtosis on most filters (p
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- 2021
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8. A novel visual ranking system based on arterial spin labeling perfusion imaging for evaluating perfusion disturbance in patients with ischemic stroke.
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Sangjoon Lee, Dong Woo Park, Tae Yoon Kim, Dong Sun Kim, Ji Young Lee, Young-Jun Lee, and Chun Ki Kim
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Medicine ,Science - Abstract
We developed a visual ranking system by combining the parenchymal perfusion deficits (PPD) and hyperintense vessel signals (HVS) on arterial spin labeling (ASL) imaging. This study aimed to assess the performance of this ranking system by correlating with subtypes classified based on dynamic susceptibility contrast (DSC) imaging for evaluating the perfusion disturbance observed in patients with ischemic stroke. 32 patients with acute or subacute infarcts detected by DSC imaging were reviewed. Each patient's brain was divided into 12 areas. ASL ranks were defined by the presence (+) or absence (-) of PPD/HVS as follows; I:-/-, II:-/+, III: +/+, and IV: +/-. DSC imaging findings were categorized based on cerebral blood flow (CBF) and time to peak (TTP) as normal (normal CBF/TTP), mismatched (normal CBF/delayed TTP), and matched (decreased CBF/delayed TTP). Two reviewers rated perfusion abnormalities in the total of 384 areas. The four ASL ranks correlated well with the DSC subtypes (Spearman's r = 0.82). The performance of ASL ranking system was excellent as indicated by the area under the curve value of 0.94 using either matched or mismatched DSC subtype as the gold standard and 0.97 using only the matched DSC subtype as the gold standard. The two methods were in good-to-excellent agreement (maximum κ-values, 0.86). Inter-observer agreement was excellent (κ-value, 0.98). Although the number of patients was small and the number of dropouts was high, our proposed, ASL-based visual ranking system represented by PPD and HVS provides good, graded estimates of perfusion disturbance that agree well with those obtained by DSC perfusion imaging.
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- 2020
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9. The sensitivity of ship resistance to wall-adjacent grids and near-wall treatments
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Dong Woo Park and Sang Bong Lee
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Ocean engineering ,TC1501-1800 ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
Numerical simulations of turbulent flows around KCS have been performed to study the sensitivity of ship resistance to wall-adjacent grids and disclose the influence of near-wall treatment on the sensitivity of ship resistance. The resistance coefficients of viscous and pressure forces were compared when using realizable k-ε and SST k-ω turbulence models in structured and unstructured grids, respectively. The calculation of friction velocity was found to be mainly responsible for the reduction of viscous and total resistances when the height of wall-adjacent cells increased. Since the assumption of equilibrium state between turbulent production and dissipation was not met in a bulbous bow, it was more reasonable to iteratively calculate the friction velocity from empirical laws of the wall for near-wall treatment rather than explicitly estimate it from the turbulent kinetic energy.
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- 2018
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10. Clinicoradiological Features and Outcomes of Patients with Atherosclerotic Basilar Artery Steno-Occlusion: A Single-Center Experience
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Ga Hye Shin, Young-Jun Lee, Dong Woo Park, Ji Young Lee, Young Seo Kim, Hyun Young Kim, and Hyeong-Joong Yi
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basilar artery ,atherosclerosis ,stenosis ,cerebral infarction ,medicine ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
Purpose: There is a relatively higher risk of peri-procedural stroke following elective stenting of patients with basilar artery (BA) occlusion compared with stenting of intracranial arteries. We sought to diagnose stroke risks in patients with BA steno-occlusive disease by describing their clinicoradiological features and by demonstrating that appropriate treatment would lead to favorable outcomes. Materials and Methods: A total of 92 patients who were treated from 2004 to 2016 for severe stenosis or occlusion of BA based on MR or CT angiography were enrolled in the study. We assessed clinical features, radiologic findings, and other clinical outcomes such as the degree of disability as determined by the modified Rankin Scale. Results: A total of 49 of the 92 patients (53.3%) had no relevant symptoms. The risk of a recurrent or new infarct in the relevant area was 4.59%/year. Following treatment, more than 50% of the 92 patients had favorable outcomes. A recurrent or new infarct was found in 9 (20.5%) of the 44 patients who had a poor prognosis. There was no significant difference between the two groups with respect to compromised circulation; however, the initial infarct (16 of 48 and 29 of 44, p = 0.002) was statistically significant between the two groups. Conclusion: Atherosclerotic BA steno-occlusion disease is associated with a relatively low risk of a recurrent or new infarct and with favorable clinical outcomes following appropriate medical treatment.
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- 2017
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11. Hemorrhagic Listerial Encephalitis in a Patient with Systemic Lupus Erythematosus: A Case Report
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Hyun Gyu Lee, Ji Young Lee, Young-Jun Lee, Young Seo Kim, Hyun Young Kim, Wonjae Sung, and Dong Woo Park
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encephalitis ,listeria monocytogenes ,magnetic resonance imaging ,systemic lupus erythematosus ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
A 31-year-old female with systemic lupus erythematosus (SLE) presented with fever, headache, seizures and mental status changes. Brain MRI showed T2 hyperintense lesions in the cerebellum and frontal white matter and a lesion in the cerebellum exhibited hemorrhagic changes and peripheral ring enhancement. The MRI features of listerial encephalitis are difficult to differentiate from those of neuropsychiatric SLE and various other diseases. Here, we report a case of hemorrhagic listerial encephalitis in a patient with SLE.
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- 2017
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12. Size Reduction of an Intracranial Aneurysm after Resolution of Vasospasm: A Case Report
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Ga Hye Shin, Ji Young Lee, Young-Jun Lee, Dong Woo Park, Young Seo Kim, Hyun Young Kim, and Hyeong-Joong Yi
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cerebral aneurysm ,subarachnoid hemorrhage ,intracranial vasospasm ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
Vasospasm after subarachnoid hemorrhage may alter intracranial hemodynamics. We report a case which showed significant size reduction of an unruptured intracranial aneurysm after resolution of vasospasm. This case may suggest that aneurysm size can be affected by vasospasm, which is presumably related to changes in hemodynamics or spontaneous thrombosis.
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- 2018
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13. Effect of Penetration Enhancers on Toenail Delivery of Efinaconazole from Hydroalcoholic Preparations
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Jun Soo Park, Jeong Soo Kim, Myoung Jin Ho, Dong Woo Park, Eun A. Kim, Yong Seok Choi, Sun Woo Jang, and Myung Joo Kang
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efinaconazole ,transungual drug delivery ,hydroalcoholic solution ,permeation enhancer ,bovine hoof ,onychomycosis ,Organic chemistry ,QD241-441 - Abstract
The incorporation of permeation enhancers in topical preparations has been recognized as a simple and valuable approach to improve the penetration of antifungal agents into toenails. In this study, to improve the toenail delivery of efinaconazole (EFN), a triazole derivative for onychomycosis treatment, topical solutions containing different penetration enhancers were designed, and the permeation profiles were evaluated using bovine hoof models. In an in vitro permeation study in a Franz diffusion cell, hydroalcoholic solutions (HSs) containing lipophilic enhancers, particularly prepared with propylene glycol dicaprylocaprate (Labrafac PG), had 41% higher penetration than the HS base. Moreover, the combination of hydroxypropyl-β-cyclodextrin with Labrafac PG further facilitated the penetration of EFN across the hoof membrane. In addition, this novel topical solution prepared with both lipophilic and hydrophilic enhancers was physicochemically stable, with no drug degradation under ambient conditions (25 °C, for 10 months). Therefore, this HS system can be a promising tool for enhancing the toenail permeability and therapeutic efficacy of EFN.
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- 2021
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14. Anterior Atlantodental and Posterior Atlantodental Intervals on Plain Radiography, Multidetector CT, and MRI
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Kibo Yoon, Seung Woo Cha, Jeong Ah Ryu, Dong Woo Park, Seunghun Lee, and Kyung Bin Joo
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atlantoaxial joint ,cervical vertebrae ,plain radiography ,multidetector computed tomography ,magnetic resonance imaging ,Medical physics. Medical radiology. Nuclear medicine ,R895-920 - Abstract
Purpose To determine the normal values of the anterior atlantodental interval (AADI) and posterior atlantodental interval (PADI) on plain radiography, multidetector CT (MDCT) and MRI, as well as the dural sac width and spinal cord diameter at the atlantoaxial joint level on MRI. Materials and Methods In total, 60 subjects underwent plain radiography, MRI and MDCT. We obtained values for AADI and PADI on plain radiography, MDCT, and MRI, and for dural sac width and spinal cord diameter on MRI. Two radiologists independently measured each value and a consensus was reached. Results The average AADI was 1.5 ± 0.5 mm on plain radiography, 1.4 ± 0.3 mm on MDCT, and 1.6 ± 0.5 mm on MRI. The average PADI was 20.6 ± 2.4 mm on plain radiography, 18.0 ± 2.1 mm on MDCT, and 17.7 ± 1.9 mm on MRI. The dural sac width was 13.7 ± 1.8 mm, and the spinal cord diameter was 7.8 ± 0.7 mm. Interobserver agreement was 0.701-0.927 and intraobserver agreement was 0.681-0.937. Conclusion AADI values obtained on MDCT are significantly lower than those obtained on plain radiography or MRI. PADI values obtained on plain radiography are significantly higher than those obtained on MDCT or MRI. The dural sac width is most closely correlated with PADI values on MDCT. PADI seems to be easier to measure, more relevant, and clinically useful than AADI.
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- 2015
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15. Hydrodynamic characteristics for flow around wavy wings with different wave lengths
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Mi Jeong Kim, Hyun Sik Yoon, Jae Hwan Jung, Ho Hwan Chun, and Dong Woo Park
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Wavy leading edge ,Wave length ,Low aspect ratio wing ,Lift ,Stall ,Ocean engineering ,TC1501-1800 ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
The present study numerically investigates the effect of the wavy leading edge on hydrodynamic characteristics for the flow of rectangular wings with the low aspect ratio of 1.5. Five different wave lengths at fixed wavy amplitude have been considered. Numerical simulations are performed at a wide range of the angle of attack (0° ≤α ≤ 40°) at one Reynolds number of 106. The wavy wings considered in this study did not experience enough lift drop to be defined as the stall, comparing with the smooth wing. However, in the pre-stall region, the wavy wings reveal the considerable loss of the lift, compared to the smooth wing. In the post-stall, the lift coefficients of the smooth wing and the wavy wings are not much different. The pressure coefficient, limiting streamlines and the iso-surface of the spanwise vorticity are also highlighted to examine the effect of the wave length on the flow structures.
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- 2012
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16. Endplate effect on aerodynamic characteristics of three-dimensional wings in close free surface proximity
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Jae Hwan Jung, Mi Jeong Kim, Hyun Sik Yoon, Pham Anh Hung, Ho Hwan Chun, and Dong Woo Park
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Wing in ground ,Endplate ,Tip vortex ,Lift ,Drag ,Ocean engineering ,TC1501-1800 ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
We investigated the aerodynamic characteristics of a three-dimensional (3D) wing with an endplate in the vicinity of the free surface by solving incompressible Navier-Stokes equations with the turbulence closure model. The endplate causes a blockage effect on the flow, and an additional viscous effect especially near the endplate. These combined effects of the endplate significantly reduce the magnitudes of the velocities under the lower surface of the wing, thereby enhancing aerodynamic performance in terms of the force coefficients. The maximum lift-to-drag ratio of a wing with an endplate is increased 46% compared to that of wing without an endplate at the lowest clearance. The tip vortex of a wing-with-endplate (WWE) moved laterally to a greater extent than that of a wing-without-endplate (WOE). This causes a decrease in the induced drag, resulting in a reduction in the total drag.
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- 2012
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17. DOOMRED: A New Optimization Technique for Boosted Cascade Detectors on Enforced Training Set
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Kyoung Mu Lee and Dong Woo Park
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Telecommunication ,TK5101-6720 ,Electronics ,TK7800-8360 - Abstract
We propose a new method to optimize the completely-trained boosted cascade detector on an enforced training set. Recently, due to the accuracy and real-time characteristics of boosted cascade detectors like the Adaboost, a lot of variant algorithms have been proposed to enhance the performance given a fixed number of training data. And, most of algorithms assume that a given training set well exhibits the real world distributions of the target and non-target instances. However, this is seldom true in real situations, and thus often causes higher false-classification ratio. In this paper, to solve the optimization problem of completely trained boosted cascade detector on false-classified instances, we propose a new base hypothesis weight optimization algorithm called DOOMRED (Direct Optimization Of Margin for Rare Event Detection) using a mathematically derived error upper bound of boosting algorithms. We apply the proposed algorithm to a cascade structured frontal face detector trained by AdaBoost algorithm. Experimental results demonstrate that the proposed algorithm has competitive ability to maintain accuracy and real-time characteristic of the boosted cascade detector compared to those of other heuristic approaches while requiring reasonably small amount of optimization time.
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- 2008
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18. A study on the effect of flat plate friction resistance on speed performance prediction of full scale
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Dong-Woo Park
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Flat plate friction ,Form factor Scale effect ,Friction resistance curve ,ITTC-1957 ,Ocean engineering ,TC1501-1800 ,Naval architecture. Shipbuilding. Marine engineering ,VM1-989 - Abstract
Flat plate friction lines have been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996), and the curve developed by Katsui et al. (2005). In the second part, change in the form factor by three kinds of friction resistance curves was investtigated based on model tests, and then the brake power and the revolution that were finally determined by expansion processes of full-scale ships. When three kinds of friction resistance curves were applied to each kind of ships, these were investigated: differences between resistance and self-propulsion components induced in the expansion processes of full-scale ships, correlation of effects between these components, and tendency of each kind of ships. Finally, what friction resistance curve was well consistent with results of test operation was examined per each kind of ships.
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- 2015
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