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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.

Recent development of optical compensation scheme for liquid crystal display (LCD) enables to realise a high quality display by eliminating the unnecessary birefringence at oblique viewing directio...

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.

In this study, we observed the color performance of an organic light-emitting diode (OLED) as functions of the optical lengths of the inorganic layers on the parameter space map in order to obtain the goal of increased color performance. To design the dominant wavelength and the bandwidth of the OLED, we employed the finite-difference time-domain method to calculate the optical characteristics of the light emitted from the emitting material layer. We only handled inorganic layers such as the cathode layer, the capping layer, and the indium-tin oxide layer in OLED layers to avoid changing the electro-optical characteristics of the light emerging from the organic layers. With this simple technique, we established the optimal conditions for the optical length of each layer without any intrusion into the organic layers. In this study, we demonstrated the parameter space map for a red OLED that exhibits a 24-nm bandwidth with a peak emission at wavelength λ = 618 nm. We verified the proposed parameter space method by experimentation and present the experimental results in this paper.

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.

Herein, an electrically switchable cholesteric liquid crystal (LC) shutter from visible to infrared light was prepared using a dual frequency LC (DFLC). The fabricated device is semitransparent to visible and IR light in the planar state and opaque in the focal conic state. Both visible and IR lights are transmitted in the homeotropic state. Interestingly, switching among these states is possible by just varying the voltage and frequency. In addition, it is possible to switch between the planar (homeotropic) and homeotropic (planar) states without going to the focal conic state. The proposed device can even regulate the ambient temperature by controlling the sunlight without losing transparency. Thus, the device is expected to have potential applications as smart windows of automobiles and buildings to control the interior temperature and save energy.

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.

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.

We propose a double frequency ultraviolet (UV) exposure process that can improve the surface anchoring energy of photopolyimide (PI) embedded with reactive mesogens (RMs) for the high speed liquid ...

This paper proposes a single image haze removal algorithm that shows a marked improvement on the color attenuation prior-based method. Through a vast number of experiments on a wide variety of images, it is discovered that there are problems in the color attenuation prior, such as color distortion and background noise, which arise due to the fact that the priors do not hold true in all circumstances. Successful resolution of these problems using the proposed algorithm shows its superior performance to other state-of-the-art methods in terms of both subjective visual quality and quantitative metrics, on both synthetic and natural hazy image datasets. The proposed algorithm also is computationally friendly, due to the use of an efficient quad-decomposition algorithm for atmospheric light estimation and a simple modified hybrid median filter for depth map refinement.

This paper presents a fast and compact hardware implementation using an efficient haze removal algorithm. The algorithm employs a modified hybrid median filter to estimate the hazy particle map, which is subsequently subtracted from the hazy image to recover the haze-free image. Adaptive tone remapping is also used to improve the narrow dynamic range due to haze removal. The computation error of the proposed hardware architecture is minimized compared with the floating-point algorithm. To ensure real-time hardware operation, the proposed architecture utilizes the modified hybrid median filter using the well-known Batcher&rsquo, s parallel sort. Hardware verification confirmed that high-resolution video standards were processed in real time for haze removal.

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

Vertical alignment liquid crystal (LC) cell driven by in-plane field with 3-D polymer network exhibited no pooling mura under an external mechanical pressure; however, the operating voltage of the device was increased, because the polymer network hinders field-induced reorientation of LC. In this paper, we adopted a modified cell structure in which a counter electrode on top substrate of the conventional mode is existed, to improve upon this drawback. The proposed device in which the polymer network is formed in bulk of vertically aligned LC layer shows a very fast response time of 2 ms (rise + decay), 57% reduction in operating voltage, and also keeps image quality although the cell is curved.

A polymer-stabilized vertical alignment (PS-VA) mode with fishbone-shaped pixel electrode structure is mainly used in large-sized liquid crystal displays (LCDs) owing to its advantages such as wide viewing angle, good transmittance and fast response time. One drawback of this mode is a main bone electrode, which crosses in the center of a pixel. It causes the transmittance to decrease badly because LCs cannot be reoriented in this region, and thus, it is particularly unfavorable in an ultra-high-definition LCD. Here, we propose an innovative structure with the main bone electrode relocated to the edge area in a pixel, and investigate how this reverse directed fishbone-shaped pixel electrode structure affects electro-optic characteristics. The proposed structure shows enhanced electro-optic performance, such as the higher transmittance and the faster response time than the conventional VA mode with fishbone-shaped pixel electrode structure.

Uniformly aligned liquid crystals (LCs) are of crucial importance in a practical application, such as displays, phase modulators and virtual reality devices. Although an alignment layer using polyimide-type polymers can almost perfectly align the LCs, polymer-stabilisation at the surface using pre-mixed monomers has been attempted to reduce the fabrication process, i.e. eliminating the alignment layer, thereby reducing the fabrication cost. Here, we propose an approach to achieve a homogeneous alignment of LCs by controlling the molecular structure of reactive monomers mixed in LCs without using conventional polyimide alignment layer. The result shows an excellent initial dark state and acceptable electro-optic performance which implies that the polymer stabilisation at the surface successfully anchors the homogenous orientation of LCs. We believe that the proposed fabrication method can contribute to cost-effective fabrication process by eliminating an alignment layer with no fabrication step of ...

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.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.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.Computed tomography confirmed that diaphragm thickness was reduced in critically ill patients who underwent MV.

We investigated how surface anchoring strength affects the electro-optic (EO) characteristics of a fringe-field switching (FFS) mode. Unlike IPS mode that only azimuthal anchoring mainly contributes to the EO performances, both azimuthal and polar anchoring energies play an important role such that the transmittance increases with decreasing magnitude of azimuthal energy but increasing polar anchoring energy in the FFS mode when using a LC with positive dielectric anisotropy. In addition, weak anchoring at the electrode edge may result in change in initial LC optic axis by applied voltage stress so local control of anchoring energy is proposed.

In general, surface anchoring energy is one of the most important parameters that strongly affect electrooptical performance, especially the optical response time of liquid crystal (LC) displays. In this paper, we proposed a photoalignment method for strong surface anchoring energy by applying double ultraviolet (UV) exposure with a separated bandwidth to a photosensitive polyimide layer with embedded reactive mesogens (RMs) that can increase the anchoring energy during polymerization. We first polymerized the embedded RM molecules using long wavelength UV rays (over 340 nm), and then achieved the ordered photosensitive alignment layer using short UV rays (between 254 and 340 nm). We compared the measured surface anchoring energy and the optical response time by the proposed method with the conventional UV exposure using the in-plane switching LC mode for verification. As a result, we confirmed that the anchoring energy increased two times and the optical response time improved by 22% compared with the conventional pure UV exposure method.

We investigated how the electro-optic characteristics of the fringe-field switching (FFS) liquid crystal (LC) mode are affected by elastic constants of LCs. Unlike conventional liquid crystal (LC) devices, in which mainly the dielectric torque determines reorientation of LC, the field-induced LC reorientation in the fringe-field switching (FFS) mode is controlled first by dielectric torque and then by pure elastic torque between LCs so that the transmittance oscillates along the electrode positions. We find that elastic constants of the LC play an important role on the field-induced dynamics of the LC molecules such that the higher the splay constant is, the higher the light efficiency becomes, which is a unique characteristic of the FFS mode. The results present an important design of physical properties of LC to enhance better transmittance in the FFS mode.

In this paper, we proposed the photo-alignment method with the strong surface anchoring energy by applying the two band UV exposure method on the photosensitive PI layer embedded with reactive mesogens (RMs) for achieving the fast response time properties of the in-plane switching (IPS) LC mode. We first enhanced the interconnection between a RM polymer and a photo-alignment layer through high band ultra-violet (UV) exposure on the long pass UV filter over 340 nm and then established the alignment of LCs through low band linear polarized UV exposure at 254 nm after eliminating the UV filter. As results, we measured the surface anchoring energy and response time of the proposed photo-alignment method and also confirmed that the optical response time was reduced by approximately 22.3 % compared to that of the IPS-LC cell of pure photo-alignment layer.

We proposed a fast response time in-plane swithcing (IPS) liquid cryatal (LC) mode in the photo-alignment layer. In order to achieve the fast response time, we first enhanced the anchoring energy of the photo-alignment layer by coating the reactive mesogens (RMs) which can modify the surface condition and also applied the low cell property in the LC cell by using the positive A-plate with same effective retardation as the LC layer. In the experiments, we demonstrated that the coated RM layer can make the strong surface anchoring energy because of its strong polymer chain by the UV exposure and also confirmed the improved response time in the low cell gap IPS cell. As measured results, the response time of the proposed IPS LC cell could be improved over 56.86% and 62.18% compared with that of a conventional photo-aligned IPS cell with/without RM coating, respectively because of the low cell gap property.

In this paper, we introduce the optical approach for the calculation of optical path in arbitrary aligned birefringence media for controlling the incident light, and also calculate the ray path in representative liquid crystal (LC) modes. In calculation, we multi-dimensionally calculated the Poynting vector S and wave vector k of ordinary and extra-ordinary rays, and considered both y-axis and z-axis interfaces by using the dielectric tensor rotation method. Finally, we could achieve the exact ray path in various LC modes, and confirmed the propagating direction of the light according to azimuth angles in LC layers.

The application of a single-wall carbon-nanotube (SWCNT) and polyimide (PI) composite thin film on an indium tin-oxide (ITO) glass substrate, working as the command surface in a twisted nematic liquid crystal display (LCD), is described. SWCNTs were chopped and oxidized in a strong acid medium to make them more miscible in a polyimide solution. A film of this newly-developed PISWCNT composite was rubbed to determine the director direction for the LC molecules. The newlyfabricated command surface was examined using a laser beam profiler and atomic force microscopy. Sizes of shortened SWCNTs were characterized by using field-emission scanning electron microscopy (FE-SEM). Finally, small-sized test panels were fabricated from this composite-coated ITO glass, and their electro-optic performances were measured. Although the operating voltage to switch a cell was increased by around 41%, the switching speed was improved remarkably. The rise time of the test cells was found to be improved by around 10.12% and the decay time by around 29.77%. Thus, an overall improvement of around 16.12% in the total switching time was achieved. The change in the surface morphology of the newly-developed composite materials was found to be one of the factors responsible for the faster switching of the device. Detailed discussions are given in this report to explain the faster switching of the newly-developed twisted nematic liquid crystal display (TN-LCD). The device can be useful for practical applications.

In general, the super in-plane switching (S-IPS) liquid crystal (LC) mode is widely used for LCD applications because of its wide-viewing properties. However, it can also diminish the aperture ratio in active areas due to the zigzag pattern. In this paper, we proposed an IPS LC mode that has wide-viewing properties even if the stripe-patterned electrodes, which can provide a high transmittance property, are applied using the double-exposed UV alignment method to the upper/lower domain of the active area. The initial alignment direction of the upper/lower domain was optimized with simple experiments and we achieved both the superior dark level in the initial mode and wide-viewing properties in the applied voltage mode. As a result, we obtained an increased aperture ratio of about 10% and a higher optical transmittance of 15% compared to the conventional S-IPS LC cell because of the high aperture ratio without any optical loss of the initial dark state and viewing angle property.

We introduce an optical approach, which can improve the γ-curve distortion using a pair of positive and negative A-type retardation films only for various liquid crystal display (LCD) modes. Optimization of a pair of A-plates was performed by calculating the polarization difference (Δp) between the normal and oblique incidence under a voltage applied state as functions of the retardation and the optical axis of the used A-plates. From the calculated results, LCD modes show an improvement of the γ-curve distortion over the 60% without any loss of optical performance in the dark state.

In general, light propagating an inhomogeneous liquid crystal (LC) cell can be modeled as ‘bundle rays’ because the LC cell consists of many birefringence layers. In order to calculate the optical path of the propagating light in the inhomogeneous LC cell, we multidimensionally calculated the wavevector, k, and the Poynting vector, S, of an ordinary and an extraordinary ray at LC grid interfaces, which are isotropic to a uniaxial medium and a uniaxial-to-uniaxial medium, by using the phase matching method. Furthermore, we also investigated the transmission coefficients and transmittance of the ordinary and the extraordinary rays as a function of difference of the optical axes of the facing birefringence medium at the interface to obtain the significant rays in the LC cell. Finally, we could calculate the exact path of the significant rays in the inhomogeneous LC cell, and compared the ray path in an electrically controlled birefringence (ECB) mode and a twisted nematic (TN) LC mode.

The γ-curve represents the viewing angle characteristics of a liquid crystal (LC) cell in all gray levels, including the dark state. In this paper, we propose a optical configuration of a four-domain (4-D) twisted nematic (TN) LC cell for improving the γ-curve distortion in the oblique direction, without any deterioration in the optical property of a conventional 4-D TN cell. A positive A-plate and a negative A-plate are applied at the top and the bottom of the 4-D TN LC layer, respectively. The two A-films applied can be optimized at all viewing angles by calculating the polarization difference (Δ p ) as functions of the retardation and the optical axis of the films, so that the transmittance distortion in the middle gray scale can be compensated for in all viewing directions. As a result of a calculation of the gamma distortion index (GDI), the γ-curve can be improved by more than 70% in the off-axis at 0° and 180°, and by more than 50% in the off-axis at 90° and 270°.

We propose a planar polymeric liquid crystal (LC) lens with a low cell gap (~ 4.6 μm) for a 2-D/3-D switchable auto-stereoscopic display. The proposed lens consists of two LC layers, one is a photopolymerized LC lens layer with a non-uniform refractive index with parabolic curve distribution, and the other is a half-wave LC switching layer of the vertical alignment type, which performs the 2-D/3-D image switching. The optimized refractive index of the LC lens layer was simply realized by polymerizing the LC molecules using a reactive mesogen. The proposed LC lens allow fast 2-D/3-D switching with low voltage and a simple fabrication process because of a low cell gap of the switching layer. We verified the electro-optical characteristics of the proposed LC lens by fabricating each layer after optimizing the cell structure. The measured focal length as a function of the applied voltage in the 3-D mode was compared with the calculated focal length and we confirmed that the measured results agreed with the calculated results.

In this paper, we improved the γ-curve distortion at off-axis direction in a 4-domain (4-D) patterned vertical alignment (PVA) liquid crystal (LC) cell by applying a pair of the film patterned retarder (FPR) system with the A-film property at the conventional wide-view (WV) PVA LC cell. In order to achieve the excellent γ-curve in the 4-domain LC cell, we optimized the parameter of the pair of the patterned A-film by using the twodimensional parameter space method, which calculates the polarization difference between the normal direction and the all viewing directions under voltage applied state. As a result, we confirmed that the gamma distortion index (GDI) of the proposed optical structure is reduced to over 80% without any loss of the optical luminance and the contrast ratio in the dark state. Author Keywords Vertical alignment; γ-curve distortion; film patterned retarder; wide viewing angle; transmittance

In order to improve the image crosstalk for a film patterned retarder (FPR) of a linear polarizer type in a stereoscopic three dimensional (3D) display, we propose an optical structure with wideband and wide viewing angle characteristics and using only two half-wave retarders. This proposed half-wave retarder of the FPR 3D cell consists of a λ/2 biaxial film and a patterned λ/2 A-film. We calculated the phase retardation and confirmed the polarization states of the light passing through each film on the Poincare over all visible wavelengths by using the Stokes vector and the Muller matrix method. Then, we optimized the optical parameters of the two retardation films in the oblique direction by using the parameter space method as a function of the optical axis and the NZ parameter of the biaxial λ/2 film. Consequently, we verified that the left 3D crosstalk of the proposed FPR 3D cell could be improved by about 91.87% in the horizontal viewing direction and 97.22% in the vertical viewing direction. The right 3D crosstalk could almost maintain the crosstalk value of the conventional structure.

Wide-view (WV) film, which was introduced by Fuji Co., has been commercialized to block light leakage of twisted nematic (TN)-liquid crystal (LC) cells in a dark state when the viewing angles are in the off-axis direction. In this investigation, we designed an optical compensation structure of a TN-LC cell with an improved γ-curve, as well as a viewing angle property in the dark state. Basically, we used a pair of optical films consisting of a positive and a negative A-plate in order to avoid affecting the viewing angle property in the dark state. Then, we optimized the positive and negative A-plate to improve the viewing angle property in the gray levels by calculating polarization variations as a function of the optical axis and the retardation of the pair of the A-plates. From this calculation, we were able to show that the proposed normally white (NW) WV-TN cell exhibits wide viewing angle performance, including good γ-curve stability.

A transflective liquid crystal display using polymer-stabilised vertical alignment mode with fishbone-shaped electrode structure is proposed. Using the polymer stabilisation technique and patterned direction of pixel electrode structure, initial surface tilt angle and azimuthal angle can be well defined such that the liquid crystal is almost vertically aligned in the transmissive part while it has a certain pretilt angle that satisfies effective retardation of λ/4 with azimuthal direction of 45o with respect to the analyser in the reflective part. With optimisation of cell structures and surface tilt angles in the transmissive and reflective parts, a high performance transflective display showing excellent readability in any environment light conditions and single-gamma characteristic without using any retardation film or in-cell retarder can be achieved.

In this paper, we proposed the novel hybrid guest-host liquid crystal display using the negative charged black particles in order to improve the low contrast ratio. We designed patterned electrode in order to switch the charged particle to the opposite electrode and improved the electro-optical characteristics by optimize the mixture of guest materials. In Comparison with the Heilmeier Guest-Host mode, proposed hybrid guest-host structure showed 80% reduction of transmittance in dark state, and the performance was examined by comparing contrast ratio.

Introduction: We evaluated the diagnostic yield of cytologic analysis of bronchial washing in addition to forceps biopsy on the basis of bronchoscopic appearance and histologic type in lung cancer. Methods: This retrospective study included 611 patients who had lung cancer and underwent bronchoscopic procedures between April 2003 and December 2008. Bronchoscopic appearance was classified into six types (tumor, infiltrative, necrotic, normal, compressive and aspecific) on the basis of endoscopic morphology. Results: The forceps biopsy were positive in 492 cases (80.5%), and the diagnostic yield of the combination of forceps biopsy with cytologic analysis of bronchial washing was 84.1% (514/611 cases), that is, a statistically significant increase of 3.6% (P 0.05). However, in the case of normal and compressive lesions, the addition of forceps biopsy to washing cytologic analysis significantly increased the diagnostic yield (P 0.05). Conclusions: The combination of forceps biopsy and washing cytologic analysis offers a better diagnostic yield than biopsy alone in diagnosing lung cancer. Both procedures should be performed during bronchoscopy even if no endobronchial lesion is present. Please cite this paper as: Lee GD, Kim HC, Kim YE, Lee SJ, Cho YJ, Jeong YY, Jeon K-N, Jang IS, Lee JD and Hwang YS. Value of cytologic analysis of bronchial washings in lung cancer on the basis of bronchoscopic appearance. Clin Respir J 2013; 7: 128–134.