Publications by authors named "Byungjoo Choi"

Urban policies have recently been formulated, following the increasing interest in pedestrian-friendly cities, people-centered safety, and accessibility. Despite the research efforts on physical walking safety, safety evaluations centered on pedestrian perception have been under-reported. Investigating the factors affecting pedestrian subjective safety perception is critical to promoting walking intention because pedestrians forgo walking if they feel unsafe.

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Introduction: Safety participation has gained increasing attention as an important dimension of workers' safety behaviors. Although previous studies attempted to identify factors affecting workers' safety participation, only a few studies paid attention to the psychological mechanisms behind it. Therefore, this study aimed to develop and test a research model that explains how management factors are implicated in workers' safety participation.

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In recent times, the haptic actuators have been providing users with tactile feedback via vibration for a realistic experience. The vibration spring must be designed thin and small to use a haptic actuator in a smart device. Therefore, considerable interests have been exhibited with respect to the impact characteristics of these springs.

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Both immediate and delayed hypersensitivity reactions to iodinated contrast media (ICM) are relatively common. However, there are few data to determine the clinical utility of immunologic evaluation of ICM. To evaluate the utility of ICM skin testing in patients with ICM hypersensitivity, 23 patients (17 immediate and 6 delayed reactions) were enrolled from 3 university hospitals in Korea.

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Background: Arterial stiffening may affect regional myocardial function in hypertensive patients with normal ejection fraction (EF).

Methods: Brachial-ankle pulse wave velocity (PWV) was measured in 70 patients, of mean age 48 ± 14 years, with untreated hypertension and EF > 55%. Using two-dimensional-speckle tracking echocardiography, we measured longitudinal and circumferential strain (ε) and strain rate (SR).

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Background: Right ventricular apical (RVA) pacing induces left ventricular (LV) dyssynchrony, increases the risk of persistent atrial fibrillation in the long term. The aim was to investigate the effects of RVA pacing on left atrial (LA) function, which are unknown.

Methods: Echocardiographic evaluation including LV dyssynchrony based on conventional Doppler, tissue Doppler imaging and speckle tracking strain echocardiography was done before and after (12 months) single-chamber ventricular pacemaker implantation in 40 patients with sick sinus syndrome.

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Background: Left atrial appendage (LAA) anatomy and function have been well characterized both in healthy and diseased people, whereas relatively little attention has been focused on the right atrial appendage (RAA). We sought to evaluate RAA flow velocity and to compare these parameters with LAA indices and with a study of biomarkers, such as brain natriuretic peptide, among patients with sinus rhythm (SR) and atrial fibrillation (AF).

Methods: In a series of 79 consecutive patients referred for transesophageal echocardiography, 43 patients (23 with AF and 20 controls) were evaluated.

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A right atrial and inferior vena caval thrombus in a structurally normal heart is a very rare condition. We report a case of such a thrombus in a 66-year-old woman. She was admitted to our hospital with recent onset dyspnea.

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Background: We evaluated the myocardial contractile reserve related to exercise-induced changes in functional mitral regurgitation (MR) by tissue Doppler imaging (TDI).

Methods: Supine bicycle exercise was performed in 35 patients with nonischemic cardiomyopathy (age 51 +/- 12 years; EF < 40%) and resting, and peak exercise 2D echocardiographic parameters, and TDI data were obtained. V(avg) was defined as the average of peak systolic velocities of six basal LV segments by TDI.

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Background: Triplane tissue Doppler imaging (TDI) makes it possible to simultaneously obtain three apical view images and to measure the dyssynchrony index (DS) for 12 segments in patients with atrial fibrillation (AF). We evaluated the feasibility of using triplane TDI to assess intraventricular asynchrony in AF.

Methods: In 50 patients with AF, triplane TDI was used for the analysis of myocardial velocity curves of 12 (six basal and six mid) left ventricular (LV) segments by apical two-, three-, and four-chamber views.

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A well-developed collateral circulation is frequently observed in patients with total coronary occlusion. However, the fate of the collateral circulation after successful percutaneous transluminal coronary angioplasty (PTCA) has not been fully characterized. The purpose of this study was to compare the efficacy of coronary angiography and myocardial contrast echocardiography (MCE) in the evaluation of the collateral circulation after PTCA and to assess the temporal changes of the collateral circulation after successful PTCA of a totally occluded artery by using these 2 diagnostic methods.

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