Hybrid-Type Transparent Organic Light Emitting Diode with High Contrast Using Switchable Windows.

Transparent organic light emitting diode (OLED) display is one of the most promising devices among next-generation information displays because of beneficial characteristics, such as self-emissive and optically clear properties. Nevertheless, in conventional transparent OLED display devices, there are serious intrinsic problems in terms of the transmittance in the dark state because of empty windows in the cell, so the contrast ratio of the transparent OLED display would be deteriorated even though it can exhibit excellent bright state. In general, the transparent mode using the OLED device applies an empty area in each pixel because an emitting device could never reveal the background image, so the transparent OLED should contain the empty area in the pixel for transparent images. This may cause the optical degradation in the dark state. To solve this problem, we propose hybrid-type transparent OLED display modes that apply a liquid crystal (LC) to the transparent window part of the empty space. In this paper, we applied two dichroic LC modes- which use an electrically controlled birefringence (ECB) mode (Heilmeier type) for the polarized mode and a cholesteric LC mode (Guest-Host mode) for the non-polarized mode-to the empty area. In each hybrid mode, we have observed optical performance, including the transmittance in the dark/bright state, contrast ratio and response time as a function of cell parameters. As a result, we confirmed that the dark state and the contrast ratio could be improved by applying the proposed modes without serious decay of the transmittance in the bright state.

Adapting a Dehazing System to Haze Conditions by Piece-Wisely Linearizing a Depth Estimator.

Haze is the most frequently encountered weather condition on the road, and it accounts for a considerable number of car crashes occurring every year. Accordingly, image dehazing has garnered strong interest in recent decades. However, although various algorithms have been developed, a robust dehazing method that can operate reliably in different haze conditions is still in great demand. Therefore, this paper presents a method to adapt a dehazing system to various haze conditions. Under this approach, the proposed method discriminates haze conditions based on the haze density estimate. The discrimination result is then leveraged to form a piece-wise linear weight to modify the depth estimator. Consequently, the proposed method can effectively handle arbitrary input images regardless of their haze condition. This paper also presents a corresponding real-time hardware implementation to facilitate the integration into existing embedded systems. Finally, a comparative assessment against benchmark designs demonstrates the efficacy of the proposed dehazing method and its hardware counterpart.

Design of a Structure for Optimized Optical Performance of a Full Colored Organic Light-Emitting Diode on a Parameter Space Map.

In general, optical properties of a top-emitting organic light-emitting diode (OLED) are dependent on the cavity effect of the OLED structure. Therefore, the optical path length of the many thin solid films in the OLED, which is strongly affected by the refractive index and thickness of each material, controls the cavity effect of the cell. In previous research, a parameter space method for optimizing the inorganic layer thickness of a red OLED structure was introduced to achieve the required bandwidth and peak wavelength. This is a simple method with high accuracy and can also be applied to red, green, and blue OLED structures. To design an OLED cell with a practical approach, however, the RGB OLED device requires the thickness of each inorganic layer and organic layer in all three R, G, and B OLED structures to be same. In this study, we applied the parameter space method to an RGB OLED device to find out and optimize the thickness of three inorganic parameters: Indium Tin Oxide (ITO), cathode, and capping layer (CPL) using the finite-difference time-domain (FDTD) method. The parameters ITO, cathode, and CPL were scanned from 18 to 21 nm, 5 to 100 nm, and 10 to 200 nm, respectively. The peak wavelength and bandwidth lines of the three spectral colors were placed on a map of the three inorganic layer thickness parameters to find the optimized points that can provide the desired optical characteristics with the same film thickness in the cell.

Automating a Dehazing System by Self-Calibrating on Haze Conditions.

Existing image dehazing algorithms typically rely on a two-stage procedure. The medium transmittance and lightness are estimated in the first stage, and the scene radiance is recovered in the second by applying the simplified Koschmieder model. However, this type of unconstrained dehazing is only applicable to hazy images, and leads to untoward artifacts in haze-free images. Moreover, no algorithm that can automatically detect the haze density and perform dehazing on an arbitrary image has been reported in the literature to date. Therefore, this paper presents an automated dehazing system capable of producing satisfactory results regardless of the presence of haze. In the proposed system, the input image simultaneously undergoes multiscale fusion-based dehazing and haze-density-estimating processes. A subsequent image blending step then judiciously combines the dehazed result with the original input based on the estimated haze density. Finally, tone remapping post-processes the blended result to satisfactorily restore the scene radiance quality. The self-calibration capability on haze conditions lies in using haze density estimate to jointly guide image blending and tone remapping processes. We performed extensive experiments to demonstrate the superiority of the proposed system over state-of-the-art benchmark methods.

Haziness Degree Evaluator: A Knowledge-Driven Approach for Haze Density Estimation.

Haze is a term that is widely used in image processing to refer to natural and human-activity-emitted aerosols. It causes light scattering and absorption, which reduce the visibility of captured images. This reduction hinders the proper operation of many photographic and computer-vision applications, such as object recognition/localization. Accordingly, haze removal, which is also known as image dehazing or defogging, is an apposite solution. However, existing dehazing algorithms unconditionally remove haze, even when haze occurs occasionally. Therefore, an approach for haze density estimation is highly demanded. This paper then proposes a model that is known as the haziness degree evaluator to predict haze density from a single image without reference to a corresponding haze-free image, an existing georeferenced digital terrain model, or training on a significant amount of data. The proposed model quantifies haze density by optimizing an objective function comprising three haze-relevant features that result from correlation and computation analysis. This objective function is formulated to maximize the image's saturation, brightness, and sharpness while minimizing the dark channel. Additionally, this study describes three applications of the proposed model in hazy/haze-free image classification, dehazing performance assessment, and single image dehazing. Extensive experiments on both real and synthetic datasets demonstrate its efficacy in these applications.

Visibility Restoration: A Systematic Review and Meta-Analysis.

Image acquisition is a complex process that is affected by a wide variety of internal and environmental factors. Hence, visibility restoration is crucial for many high-level applications in photography and computer vision. This paper provides a systematic review and meta-analysis of visibility restoration algorithms with a focus on those that are pertinent to poor weather conditions. This paper starts with an introduction to optical image formation and then provides a comprehensive description of existing algorithms as well as a comparative evaluation. Subsequently, there is a thorough discussion on current difficulties that are worthy of a scientific effort. Moreover, this paper proposes a general framework for visibility restoration in hazy weather conditions while using haze-relevant features and maximum likelihood estimates. Finally, a discussion on the findings and future developments concludes this paper.

Single-Image Visibility Restoration: A Machine Learning Approach and Its 4K-Capable Hardware Accelerator.

In recent years, machine vision algorithms have played an influential role as core technologies in several practical applications, such as surveillance, autonomous driving, and object recognition/localization. However, as almost all such algorithms are applicable to clear weather conditions, their performance is severely affected by any atmospheric turbidity. Several image visibility restoration algorithms have been proposed to address this issue, and they have proven to be a highly efficient solution. This paper proposes a novel method to recover clear images from degraded ones. To this end, the proposed algorithm uses a supervised machine learning-based technique to estimate the pixel-wise extinction coefficients of the transmission medium and a novel compensation scheme to rectify the post-dehazing false enlargement of white objects. Also, a corresponding hardware accelerator implemented on a Field Programmable Gate Array chip is in order for facilitating real-time processing, a critical requirement of practical camera-based systems. Experimental results on both synthetic and real image datasets verified the proposed method's superiority over existing benchmark approaches. Furthermore, the hardware synthesis results revealed that the accelerator exhibits a processing rate of nearly 271.67 Mpixel/s, enabling it to process 4K videos at 30.7 frames per second in real time.

Single Image Haze Removal from Image Enhancement Perspective for Real-Time Vision-Based Systems.

Vision-based systems operating outdoors are significantly affected by weather conditions, notably those related to atmospheric turbidity. Accordingly, haze removal algorithms, actively being researched over the last decade, have come into use as a pre-processing step. Although numerous approaches have existed previously, an efficient method coupled with fast implementation is still in great demand. This paper proposes a single image haze removal algorithm with a corresponding hardware implementation for facilitating real-time processing. Contrary to methods that invert the physical model describing the formation of hazy images, the proposed approach mainly exploits computationally efficient image processing techniques such as detail enhancement, multiple-exposure image fusion, and adaptive tone remapping. Therefore, it possesses low computational complexity while achieving good performance compared to other state-of-the-art methods. Moreover, the low computational cost also brings about a compact hardware implementation capable of handling high-quality videos at an acceptable rate, that is, greater than 25 frames per second, as verified with a Field Programmable Gate Array chip. The software source code and datasets are available online for public use.

Risk Factor and Mortality in Patients with Pulmonary Embolism Combined with Infectious Disease.

BACKGROUND: Infectious conditions may increase the risk of venous thromboembolism. The purpose of this study was to evaluate the risk factor for combined infectious disease and its influence on mortality in patients with pulmonary embolism (PE). METHODS: Patients with PE diagnosed based on spiral computed tomography findings of the chest were retrospectively analyzed. They were classified into two groups: patients who developed PE in the setting of infectious disease or those with PE without infection based on review of their medical charts. RESULTS: Of 258 patients with PE, 67 (25.9%) were considered as having PE combined with infectious disease. The sites of infections were the respiratory tract in 52 patients (77.6%), genitourinary tract in three patients (4.5%), and hepatobiliary tract in three patients (4.5%). Underlying lung disease (odds ratio [OR], 3.69; 95% confidence interval [CI], 1.926-7.081; p<0.001), bed-ridden state (OR, 2.84; 95% CI, 1.390-5.811; p=0.004), and malignant disease (OR, 1.867; 95% CI, 1.017-3.425; p=0.044) were associated with combined infectious disease in patients with PE. In-hospital mortality was higher in patients with PE combined with infectious disease than in those with PE without infection (24.6% vs. 11.0%, p=0.006). In the multivariate analysis, combined infectious disease (OR, 4.189; 95% CI, 1.692-10.372; p=0.002) were associated with non-survivors in patients with PE. CONCLUSION: A substantial portion of patients with PE has concomitant infectious disease and it may contribute a mortality in patients with PE.

Body Mass Index as a Predictor of Acute Kidney Injury in Critically Ill Patients: A Retrospective Single-Center Study.

BACKGROUND: The aim of this study was to examine the influence of body mass index (BMI) on the development of acute kidney injury (AKI) in critically ill patients in intensive care unit (ICU). METHODS: Data of patients admitted to medical ICU from December 2011 to May 2014 were retrospectively analyzed. Patients were classified into three groups according to their BMI: underweight (<18.5 kg/m²), normal (18.5-24.9 kg/m²), and overweight (≥25 kg/m²). The incidence of AKI was compared among these groups and factors associated with the development of AKI were analyzed. AKI was defined according to the Risk, Injury, Failure, Loss of kidney function, and End-stage (RIFLE) kidney disease criteria. RESULTS: A total of 468 patients were analyzed. Their mean BMI was 21.5±3.9 kg/m², including 102 (21.8%) underweight, 286 (61.1%) normal-weight, and 80 (17.1%) overweight patients. Overall, AKI occurred in 82 (17.5%) patients. The overweight group had significantly (p<0.001) higher incidence of AKI (36.3%) than the underweight (9.8%) or normal group (15.0%). In addition, BMI was significantly higher in patients with AKI than that in those without AKI (23.4±4.2 vs. 21.1±3.7, p<0.001). Multivariate analysis showed that BMI was significantly associated with the development of AKI (odds ratio, 1.893; 95% confidence interval, 1.224-2.927). CONCLUSION: BMI may be associated with the development of AKI in critically ill patients.

Altered Thoracic Cage Dimensions in Patients with Chronic Obstructive Pulmonary Disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) may cause changes in the shape of the thoracic cage by increasing lung volume and hyperinflation. This study investigated changes in thoracic cage dimensions and related factors in patients with COPD. METHODS: We enrolled 85 patients with COPD (76 males, 9 females; mean age, 70.6±7.1 years) and 30 normal controls. Thoracic cage dimensions were measured using chest computed tomography at levels 3, 6, and 9 of the thoracic spine. We measured the maximal transverse diameter, mid-sagittal anteroposterior (AP) diameter, and maximal AP diameter of the right and left hemithorax. RESULTS: The average AP diameter was significantly greater in patients with COPD compared with normal controls (13.1±2.8 cm vs. 12.2±1.13 cm, respectively; p=0.001). The ratio of AP/transverse diameter of the thoracic cage was also significantly greater in patients with COPD compared with normal controls (0.66±0.061 vs. 0.61±0.86; p=0.002). In COPD patients, the AP diameter of the thoracic cage was positively correlated with body mass index (BMI) and 6-minute walk test distance (r=0.395, p<0.001 and r=0.238, p=0.028) and negatively correlated with increasing age (r=-0.231, p=0.034). Multiple regression analysis revealed independent correlation only between BMI and increased ratio of AP/transverse diameter of the thoracic cage (p<0.001). CONCLUSION: Patients with COPD exhibited an increased AP diameter of the thoracic cage compared with normal controls. BMI was associated with increased AP diameter in these patients.

Tuberculosis presenting as isolated bronchonodal fistula in a patient with systemic lupus erythematosus: Case report.

RATIONALE: Lymph node is a preferred site for extrapulmonary tuberculosis (TB). In the thorax, mediastinal tuberculous lymph nodes can erode adjacent structures such as heart, aorta, and esophagus, forming fistula, and causing fatal consequences. However, tuberculous bronchonodal fistula as a complication of lymph node TB in adults is rarely known in terms of imaging or clinical findings. Here, a case of isolated tuberculous bronchonodal fistula appearing as the first presentation of TB in a 74-year-old male with systemic lupus erythematosus (SLE) is reported. PATIENT CONCERN: A 74-year-old male with SLE visited the hospital with dry cough. In family history, his son was treated for pulmonary TB 9 years previously. Laboratory test revealed increased C-reactive protein level and erythrocyte sedimentation rate. Chest computed tomography (CT) scan revealed a necrotic lymph node in the right hilar area connected to the inferior wall of the right upper lobe bronchus and the lateral wall of bronchus intermedius. DIAGNOSES: On bronchoscopy performed under guidance of 3-dimensionally reconstructed CT image, fistula formation between the right hilar lymph node and 2 bronchi (the right upper lobe and intermediate bronchus) was confirmed. Sputum culture revealed growth of Mycobacterium tuberculosis. INTERVENTION: Anti-TB medication with isoniazid, ethambutol, pyrazinamide, and moxifloxacin for 9 months. OUTCOME: The patient's symptom was gradually improved. Follow-up bronchoscopy performed at 3 months after starting the medication revealed decreased size of the fistula. LESSONS: This is a rare case of bronchonodal fistula appearing as the first presentation of TB in a 74-year-old male patient with SLE. CT provided useful information regarding the origin and progress of the disease.

Serum Albumin and Disease Severity of Non-Cystic Fibrosis Bronchiectasis.

BACKGROUND: A clinical classification system has been developed to define the severity and predict the prognosis of subjects with non-cystic fibrosis (CF) bronchiectasis. We aimed to identify laboratory parameters that are correlated with the bronchiectasis severity index (BSI) and FACED score. METHODS: The medical records of 107 subjects with non-CF bronchiectasis for whom BSI and FACED scores could be calculated were retrospectively reviewed. The correlations between the laboratory parameters and BSI or FACED score were assessed, and multiple-linear regression analysis was performed to identify variables independently associated with BSI and FACED score. An additional subgroup analysis was performed according to sex. RESULTS: Among all of the enrolled subjects, 49 (45.8%) were male and 58 (54.2%) were female. The mean BSI and FACED scores were 9.43 ± 3.81 and 1.92 ± 1.59, respectively. The serum albumin level (r = -0.49), bilirubin level (r = -0.31), C-reactive protein level (r = 0.22), hemoglobin level (r = -0.2), and platelet/lymphocyte ratio (r = 0.31) were significantly correlated with BSI. Meanwhile, serum albumin (r = -0.37) and bilirubin level (r = -0.25) showed a significant correlation with the FACED score. Multiple-linear regression analysis showed that the serum bilirubin level was independently associated with BSI, and the serum albumin level was independently associated with both scoring systems. Subgroup analysis revealed that the level of uric acid was also a significant variable independently associated with the BSI in male bronchiectasis subjects. CONCLUSIONS: Several laboratory variables were identified as possible prognostic factors for non-CF bronchiectasis. Among them, the serum albumin level exhibited the strongest correlation and was identified as an independent variable associated with the BSI and FACED scores.

Computed tomography confirms a reduction in diaphragm thickness in mechanically ventilated patients.

PURPOSE: Patients who require mechanical ventilation (MV) may experience diaphragm atrophy, which may delay the discontinuation of MV. Here, we used computed tomographic (CT) scans to confirm this phenomenon. METHOD AND MATERIALS: Patients who underwent two chest CT scans while on MV were retrospectively evaluated. Diaphragm thickness was measured using a three-dimensional CT image processing program. RESULTS: Thirteen patients, including 8 men, who underwent 26 CT scans were assessed. The mean age was 67.8 ± 7.5 years. The interval between CT scans was 18.4 ± 14.9 days. The first CT scans revealed that the mean thicknesses of the left and right sides of the diaphragm were 3.8 ± 0.6 and 3.9 ± 0.8 mm, respectively (total: 7.7 ± 1.4 mm). These values were significantly reduced to 3.4 ± 0.6 and 3.5 ± 0.9 mm, respectively, (total: 6.9 ± 1.5 mm) after the second scan (P < .01). No significant change in body weight (57.3 ± 12.6 vs. 56.7 ± 11.6 kg) or body mass index (21.8 ± 5.1 vs. 21.6 ± 4.8 kg/m(2)) was observed. CONCLUSION: Computed tomography confirmed that diaphragm thickness was reduced in critically ill patients who underwent MV.

Film patterned retarder for stereoscopic three-dimensional display using ink-jet printing method.

We propose a film patterned retarder (FPR) for stereoscopic three-dimensional display with polarization glasses using ink-jet printing method. Conventional FPR process requires coating of photo-alignment and then UV exposure using wire-grid mask, which is very expensive and difficult. The proposed novel fabrication method utilizes a plastic substrate made of polyether sulfone and an alignment layer, poly (4, 4' - (9, 9 -fluorenyl) diphenylene cyclobutanyltetracarboximide) (9FDA/CBDA) in which the former and the latter aligns reactive mesogen along and perpendicular to the rubbing direction, respectively. The ink-jet printing of 9FDA/CBDA line by line allows fabricating the cost effective FPR which can be widely applied for 3D display applications.

A high transmittance color liquid crystal display mode with controllable color gamut and transparency.

In this paper, we propose a color transparent liquid crystal (LC) mode that can control the properties of the color gamut and transparency in a single panel. To achieve high transmittance in the transparent LC mode, a reactive mesogen (RM) with embedded color dichroic dyes was applied instead of a color filter. Basically, the LC mode applied a 3-terminal electrode structure to switch between the transparent LC mode and the conventional color LC mode. Depending on the direction of the applied voltage, we can operate both the color mode and the transparent mode in a single panel, and modulate the transparency and color purity of the cell through appropriate voltage control. In the experiments, we confirmed that the transmittance and the color gamut of the cell were 39.4% and 2% in the transparent LC mode and 14.9% and 34% in the color LC mode, respectively. Modulation of the color gamut and transparency between each LC mode are also demonstrated in the paper.

Effects of three-dimensional polymer networks in vertical alignment liquid crystal display controlled by in-plane field.

Polymer network in vertical alignment liquid crystal cell driven by in-plane field (VA-IPS) is formed in three dimensions to achieve fast response time and to keep the liquid crystal alignment even when an external pressure is applied to the cell. The network formed by UV irradiation to vertically aligned liquid crystal cell with reactive mesogen does not disturb a dark state while exhibiting very fast decaying response time less than 2ms in all grey scales and almost zero pooling mura. The proposed device has a strong potential to be applicable to field sequential display owing to super-fast response time and flexible display owing to polymer network in bulk which supports a gap between two substrates.

Wideband antireflective circular polarizer exhibiting a perfect dark state in organic light-emitting-diode display.

We proposed wideband antireflective circular polarizer for realizing a true black state in all viewing directions in organic light-emitting-diode displays (OLEDs). Present commercialized wideband circular polarizer consisted of a half wave and a quarter wave plates having the refractive index parameter (Nz) of 1.5 in both films exhibits light leakage in the oblique viewing directions, deteriorating image quality of a black state. We evaluated Nzs of both films and proposed a new wideband antireflective circular polarizer with a perfect dark state in all viewing directions with Nz = 0.5 in both plates, which will greatly improve image quality of OLEDs.

Is daily headache related to asthma? Results from a population-based survey.

OBJECTIVE: Despite the high worldwide prevalence of asthma and headache, little is known about the association between these conditions. The objective of our study was to evaluate the association between asthma and daily headache in a representative sample of the general population of South Korea. METHODS: We retrospectively analyzed 7984 individuals included in the Second Korean National Health and Nutrition Examination Survey (KNHANES II), a prospectively administered survey performed in 2001 by a government organization within the Ministry of Health and Welfare. After adjustment of risk factors for daily headache, multivariate logistic regression analysis was performed to evaluate the association between asthma and daily headache. RESULTS: Of 7984 individuals, 69 (0.9%) had daily headache and 429 (5.4%) had asthma symptoms. Daily headache was significantly more prevalent in subjects with asthma symptoms (14/429, 3.3%) than in those without (55/7555, 0.7%; p < 0.001). Of the 4833 nonsmokers, 46 (1.0%) had daily headache and 287 (5.9%) had asthma symptoms, with daily headache being significantly more prevalent in subjects with asthma symptoms (11/231, 4.8%) than in those without (35/4602, 0.8%; p < 0.001). Multivariate logistic regression showed that the odds ratios for daily headache were 2.3 (95% CI: 1.21-4.33, p = 0.01) in all individuals with asthma symptoms and 3.4 (95% CI: 1.65-7.12, p = 0.001) in nonsmokers with asthma symptoms. CONCLUSION: Individuals with asthma symptoms are at higher risk of daily headache than those without the symptoms, suggesting a link between these conditions.

Optical approach to improve the γ curve in a vertical-alignment liquid-crystal cell.

In this Letter, we propose an optical configuration of a four-domain vertical-alignment (VA) liquid-crystal (LC) cell, which can improve the γ-curve distortion by using a pair of patterned A plates, without any change in cell structure. In order to find the optimal parameter value of the patterned A film, we calculated the polarization difference between the normal direction and the all-viewing direction as functions of the optical axes and the retardation (Δnd) under the voltage applied state. Based on the calculated results, the proposed LC cell showed an improvement in γ-curve distortion of more than 80% in each oblique viewing angle compared to a conventional wide-view VA LC cell, without any loss of optical performance in the dark state.