• Wind and Structures
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• 제14권5호
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• pp.435-447
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• 2011

A Computational Fluid Dynamics model is presented in this study for the simulation of the complex fluid flows with free surfaces inside the Tuned Liquid Column Dampers in horizontal motion. The characteristics of the fluid model of the TLCD in horizontal motion include the free surface of the multiphase flow and the horizontal moving frame. In this study, the time depend unsteady Standard ${\kappa}-{\varepsilon}$ turbulent model based on Navier-Stokes equations is chosen. The volume of fluid (VOF) method and sliding mesh technique are adopted to track the free surface of water inside the vertical columns of TLCD and treat the moving boundary of the walls of TLCD in horizontal motion. Several model solution parameters comprising different time steps, mesh sizes, convergence criteria and discretization schemes are examined to establish model parametric independency results. The simulation results are compared with the experimental data in the dimensionless amplitude of the water column in four different configured groups of TLCDs with four different orifice areas. The predicted natural frequencies and the head loss coefficient of TLCDs from CFD model are also compared with the experimental data. The predicted numerical results agree well with the available experimental data.

• Journal of Advanced Marine Engineering and Technology
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• 제29권1호
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• pp.68-77
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• 2005

A transient liquid crystal technique has become one of the most effective ways in measuring the local heat transfer coefficients on the entire surface. The key Point of this technique is to convert the inlet flow temperature into an exponential temperature profile using a mesh heater. In order to verify the validity of this technique. the heat transfer characteristics on the wall surface by a pair of longitudinal vortices is investigated experimently and numerically. A standard ${\kappa}-{\varepsilon}$ is used for the numerical analysis of turbulent flow field. It is found from experiment and numerical analysis that two peak values exist over the whole domain. as the longitudinal vortices move to the farther downstream. these peak values decrease and the dimensionless averaged Nusselt number with the lapse of time is maintained nearly at constant values. The experiment results obtained from the present experiment in terms of the transient liquid crystal technique are in good agreement with the numerical results. Therefore, the transient liquid crystal technique developed for the measurement of heat transfer coefficient is proved to be a valid method.

• Imaging Science in Dentistry
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• 제30권1호
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• pp.49-54
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• 2000

Purpose : To compare the diagnostic performance of clinical and radiologic examination for the interproximal caries on intraoral periapical radiographs and to evaluate the value of periapical radiographs. Methods: One hundred seven dental patients were examined clinically, with a mouth mirror and an explorer, by a dentist at the department of oral medicine, and the presence or absence of interproximal caries lesion was recorded. The patients were prescribed one or more dental periapical radiographs. Radiographs were assessed for the presence of interproximal caries by three oral and maxillofacial radiologists independantly. Two thousand sixty interproximal surfaces were included in this study. The diagnostic accuracies of clinical and radiologic examinations for interproximal caries were calculated. To assess the degree of agreement between clinical and radiologic examinations, Cohen's coefficient of agreement was computed. Results: The specificity of clinical and radiologic examination was 0.991, 0.997 and the sensitivity was 0.279, 0.985 respectively. The diagnostic accuracy of radiologic examination was statistically significantly higher than that of clinical examination (P<0.05). Cohen's kappa value of clinical and radiologic examination was 0.335, 0.942 respectively. These results suggested that clinical examination show only fair agreement, whereas radiologic examination show perfect agreement. Conclusion: The diagnositic performance of the dental periapical radiographs on interproximal caries were higher than that of clinical examination, thus this study showed the validity of periapical radiographs for detecting interproximal caries lesion without bitewing radiograph.

• 한국전문물리치료학회지
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• 제18권3호
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• pp.85-93
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• 2011

The purpose of this study was to establish the reliability and validity of the passive lumbar extension (PLE) test and prone instability test (PIT). Thirty-three subjects (14 males, 19 females) with lower back pain enrolled in the study and the subjects were divided into 2 groups (positive and negative instability groups) on the basis of radiographies of flexion and extension. Reliability was determined by the kappa coefficient and validity was examined using calculated sensitivity, specificity, and the likelihood ratio. The results showed that the reliability of the PLE test was higher than the PIT (intra-rater reliability: k=.86 and k=.81, interrater reliability: k=.65 and k=.62) and the validity of the PLE test was also higher than the PIT (sensitivity: 91% and 62%, specificity: 95% and 85% positive likelihood ratio: 20.00 and 4.10, negative likelihood ratio: .10 and .45). In conclusion, we think that the PLE test was a more reliable and valid method for lumbar instability than the PIT.

• Clinics in Shoulder and Elbow
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• 제17권3호
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• pp.107-113
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• 2014

Background: Sonoelastography (SE) is a new technique that can assess differences in tissue stiffness, the purpose of this study was to evaluate the ability of SE to assess the long head of biceps tendon alteration. Methods: Forty shoulders of 36 consecutively registered patients with clinical symptoms and conventional ultrasonography findings of biceps tendinitis or tendinosis, and 40 asymptomatic shoulders of 20 healthy volunteers were assessed with SE. Transverse and longitudinal images of long head of biceps tendon were obtained using SE. SE images were performed by one orthopedic surgeon and evaluated by two orthopedic surgeons using an experimentally proven color grading system. Results: The transverse images of SE showed a sensitivity of 87.5%, a specificity of 95.0% and a accuracy of 91.3%, the longitudinal images of SE showed a sensitivity of 92.5%, a specificity of 90.0% and a accuracy of 91.3%. Inter-observer reliability of SE was in 'almost perfect agreement' with a weighted kappa coefficient of 0.83. Conclusions: SE is valuable in the detection of the intratendinous and peritendinous alterations of biceps tendon, and has excellent accuracy and excellent correlation with conventional ultrasound findings.

• Journal of Korean Neurosurgical Society
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• 제46권6호
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• pp.588-591
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• 2009

Radiologic findings of Bing-Neel syndrome, which is an extremely uncommon complication resulting from malignant lymphocyte infiltration into the central nervous system (CNS) in patients with Waldenstr$\ddot{o}$m's macroglobulinemia (WM), have been infrequently reported due to extreme rarity of the case. A 75-year-old man with WM presented at a neurology clinic with progressive gait and memory disturbances, and dysarthria of 2 months duration. Cerebrospinal fluid and serum protein electrophoresis and immunofixation electrophoresis showed IgM kappa-type monoclonal gammopathy. Brain magnetic resonance imaging revealed multifocal, hyperintense lesions on T2 weighted-images. Brain diffusion-weighted imaging (DWI) demonstrated hyperintensities in cerebral and cerebellar lesions that appeared isointense on apparent diffusion coefficient maps, which were compatible with vasogenic edema. Although histologic analysis is a confirmative study to prove direct cell infiltration into the brain, brain MRI with DWI may be a good supportive study to diagnose Bing-Neel syndrome.

• 보건의료산업학회지
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• 제9권2호
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• pp.81-88
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• 2015

The purpose of this study was to compare the risk-adjusted in-hospital mortality for craniotomies between logistic regression and multilevel analysis. By using patient sample data from the Health Insurance Review & Assessment Service, in-patients with a craniotomy were selected as the survey target. The sample data were collected from a total number of 2,335 patients from 90 hospitals. The sample data were analyzed with SAS 9.3. From the results of the existing logistic regression analysis and multilevel analysis, the values from the multilevel analysis represented a better model than that of logistic regression. The intra-class correlation (ICC) was 18.0%. It was found that risk-adjusted in-hospital mortality for craniotomies may vary in every hospital. The agreement by kappa coefficient between the two methods was good for the risk-adjusted in-hospital mortality for craniotomies, but the factors influencing the outcome for that were different.

• 한국지형공간정보학회:학술대회논문집
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• 한국지형공간정보학회 1993년도 학술발표회 개요집
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• pp.141-145
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• 1993

수치변화탐지에 있어서 종래의 단일 밴드 분석법에 대한 대안으로, 선정된 조합에 의한 복합 밴드의 정보를 활용하는 기하거리분석법이라는 새로운 앨고리듬을 개발하였으며, 분석된 두 앨고리듬 중 기하거리분석법이 변화탐지에 보다 좋은 결과를 나타냈다. 기하거리분석법은 식생 형 변화에 대한 복합 밴드의 정보를 활용할 수가 있고, 데이타의 양을 줄일 수 있는 장점이 있다. 하지만, 이 방법에 대해서는 여러 환경에서의 보다 세밀한 정량적 분석이 요구되어진다. 각 변화영상에 대한 최적영역수준은 여러가지 정확도지수를 분석하여 결정하였으며, (변화)구분도에 대한 표준정확도로는 카파일도계수를 적용하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권1호
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• pp.73-82
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• 2016

In order to extend the operational life of Underwater Moored Platforms (UMPs), a horizontal axis water turbine is designed to supply energy for the UMPs. The turbine, equipped with controllable blades, can be opened to generate power and charge the UMPs in moored state. Three-dimensional Computational Fluid Dynamics (CFD) simulations are performed to study the characteristics of power, thrust and the wake of the turbine. Particularly, the effect of the installation position of the turbine is considered. Simulations are based on the Reynolds Averaged Navier-Stokes (RANS) equations and the shear stress transport ${\kappa}-{\omega}$ turbulent model is utilized. The numerical method is validated using existing experimental data. The simulation results show that this turbine has a maximum power coefficient of 0.327 when the turbine is installed near the tail of the UMP. The flow structure near the blade and in the wake are also discussed.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.432-438
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• 2017

PURPOSE. The purpose of this study was to evaluate the in vitro validity of quantitative light-induced fluorescence-digital (QLF-D) and laser fluorescence (DIAGNOdent) for assessing proximal caries in extracted premolars, using digital radiography as reference method. MATERIALS AND METHODS. A total of 102 extracted premolars with similar lengths and shapes were used. A single operator conducted all the examinations using three different detection methods (bitewing radiography, QLF-D, and DIAGNOdent). The bitewing x-ray scale, QLF-D fluorescence loss (${\Delta}F$), and DIAGNOdent peak readings were compared and statistically analyzed. RESULTS. Each method showed an excellent reliability. The correlation coefficient between bitewing radiography and QLF-D, DIAGNOdent were -0.644 and 0.448, respectively, while the value between QLF-D and DIAGNOdent was -0.382. The kappa statistics for bitewing radiography and QLF-D had a higher diagnosis consensus than those for bitewing radiography and DIAGNOdent. The QLF-D was moderately to highly accurate (AUC = 0.753 - 0.908), while DIAGNOdent was moderately to less accurate (AUC = 0.622 - 0.784). All detection methods showed statistically significant correlation and high correlation between the bitewing radiography and QLF-D. CONCLUSION. QLF-D was found to be a valid and reliable alternative diagnostic method to digital bitewing radiography for in vitro detection of proximal caries.