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"Se-Yoon, Oh"
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ACTIVE: Towards Highly Transferable 3D Physical Camouflage for Universal and Robust Vehicle Evasion
2023
Adversarial camouflage has garnered attention for its ability to attack object detectors from any viewpoint by covering the entire object's surface. However, universality and robustness in existing methods often fall short as the transferability aspect is often overlooked, thus restricting their application only to a specific target with limited performance. To address these challenges, we present Adversarial Camouflage for Transferable and Intensive Vehicle Evasion (ACTIVE), a state-of-the-art physical camouflage attack framework designed to generate universal and robust adversarial camouflage capable of concealing any 3D vehicle from detectors. Our framework incorporates innovative techniques to enhance universality and robustness, including a refined texture rendering that enables common texture application to different vehicles without being constrained to a specific texture map, a novel stealth loss that renders the vehicle undetectable, and a smooth and camouflage loss to enhance the naturalness of the adversarial camouflage. Our extensive experiments on 15 different models show that ACTIVE consistently outperforms existing works on various public detectors, including the latest YOLOv7. Notably, our universality evaluations reveal promising transferability to other vehicle classes, tasks (segmentation models), and the real world, not just other vehicles.
Visualization of the effects of spiral angle on the enhancement of in-tube flow boiling in microfin tubes
by
Bergles, A E
,
Oh, S-Y
2002
A borescope was used to visualize the flow on the inside wall of both smooth and microfin tubes of 9.525 mm O.D. The purpose was to find out the effects of the grooves on the liquid flow in microfin tubes and to explain the mechanism of heat transfer enhancement. The behavior of the liquid film was observed on the inside wall of four test tubes: a smooth tube and three microfin tubes of 6DG, 18DG, and 44DG spiral angle, for mass fluxes 50,100, and 200 kg/m2s and heat fluxes 5,10, and 20 kW/m2, with test fluid refrigerant 134a. The visualization indicated that the grooves of 18DG spiral angle were the most effective in pulling the liquid upward, showing the maximum heat transfer coefficient at mass flux G = 50 kg/m2 s. At G = 200 kg/m2s, the microfin tube with 6DG spiral angle was found to be the most efficient geometry in enhancing heat transfer.
Journal Article
DTA: Physical Camouflage Attacks using Differentiable Transformation Network
by
Larasati, Harashta Tatimma
,
Kim, Howon
,
Se-Yoon, Oh
in
Camouflage
,
Environment models
,
Object recognition
2022
To perform adversarial attacks in the physical world, many studies have proposed adversarial camouflage, a method to hide a target object by applying camouflage patterns on 3D object surfaces. For obtaining optimal physical adversarial camouflage, previous studies have utilized the so-called neural renderer, as it supports differentiability. However, existing neural renderers cannot fully represent various real-world transformations due to a lack of control of scene parameters compared to the legacy photo-realistic renderers. In this paper, we propose the Differentiable Transformation Attack (DTA), a framework for generating a robust physical adversarial pattern on a target object to camouflage it against object detection models with a wide range of transformations. It utilizes our novel Differentiable Transformation Network (DTN), which learns the expected transformation of a rendered object when the texture is changed while preserving the original properties of the target object. Using our attack framework, an adversary can gain both the advantages of the legacy photo-realistic renderers including various physical-world transformations and the benefit of white-box access by offering differentiability. Our experiments show that our camouflaged 3D vehicles can successfully evade state-of-the-art object detection models in the photo-realistic environment (i.e., CARLA on Unreal Engine). Furthermore, our demonstration on a scaled Tesla Model 3 proves the applicability and transferability of our method to the real world.
An experimental investigation of the effects of spiral angle on the evaporation heat transfer coefficients in microfin tubes with visualization technique
1999
A smooth tube and five microfin tubes were tested, and evaporation heat transfer coefficients were measured and compared for mass fluxes, 50, 100 and 200 kg/m2 s, and heat fluxes, 5, 10 and 20 kW/m 2, with Refrigerant 134a as a working fluid. The evaporation heat transfer coefficients at quality 0.5 were compared among the smooth and five microfin tubes with spiral angles 6, 12, 18, 25 and 44 degrees. The effect of the spiral angle on the heat transfer coefficients was examined. It was found that the optimal spiral angle where the maximum heat transfer coefficient occurs, mainly depends on mass flux. The optimal spiral angle was 18 degrees for G=50 kg/m2 s, and 6 degrees for G=100 and 200 kg/m 2 s. A borescope was used to visualize the flow on the inside wall of test tubes. The purpose was to find out the effect of the grooves on the liquid flow in microfin tubes and to explain the mechanism of heat transfer enhancement. Temperatures on the tube wall were measured at the same axial location as the imaging sensor of the borescope, and were related to the behavior of the liquid flow on the inside wall of the tubes. The liquid flow in the grooves on the wall was found to be the most important factor in enhancing heat transfer coefficients. The liquid flowed upward along the grooves and covered the upper inside wall of the microfin tubes at G=50 kg/m2 s. When heat flux increases, the liquid flow was found at a higher position. Both liquid viscosity and surface tension decrease, when temperature increases. Thus, the lower viscosity at higher heat flux facilitated the upward motion of the liquid flow in the grooves, so that the momentum force as well as the capillary effect was found to push the liquid along the grooves.* *A CD is included with dissertation containing video clips in avi format which can be viewed with media player.
Dissertation
Experimental study of the effects of the spiral angle on evaporative heat transfer enhancement in microfin tubes
1998
The in-tube evaporative heat transfer of the hydrofluorocarbon R-134a was examined for a smooth tube and five microfin tubes. The heat transfer coefficient in the smooth tube was compared with four correlations. The Yoshida correlation was found to be the best in annular flow, and the Kandlikar correlation with F sub(K) identical with 2.33 was the best in stratified flow, but the latter needs clarification for its applicability to the low quality range because of the strong nucleate boiling effect caused by the large value of F sub(K). The effect of the spiral angle of microfin tubes was investigated to determine the optimal spiral angle. Spiral angles of 6, 12, 18, 25, and 44 degrees were tested at constant mean diameter, 8.71 mm (0.343 in.), and number of fins, 60. The optimal spiral angle was found to be mainly dependent on the mass flux, and it was 18 degrees for a mass flux of G identical with 50 kg/m super(2) times s (36.865 lbm /ft super(2) times h), 6 degrees for G identical with 100 kg/m super(2) times s (73,730 lbm/ft super(2) times h), and 6 to 18 degrees for G identical with 200 kg/m times s (147,460 lbm/ft super(2) times h).
Journal Article
Delayed blood pressure recovery after exercise stress test is associated with autonomic dysfunction and pulse pressure in a middle-aged healthy group
by
Park, Jong-Kwan
,
Oh, Seungjin
,
Lee, Hancheol
in
Analysis
,
Biology and Life Sciences
,
Blood pressure
2023
Delayed heart rate (HR) and blood pressure recovery after exercise test is known as the reliable indexes of autonomic dysfunction. Here we tried to evaluate the serial changes in various indicators during exercise test and correlations with recovery of HR and blood pressure in a normotensive healthy middle-aged group. A total of 122 patients without hypertension or diabetes was enrolled (mean age, 55.6 ± 11.0; male, 56.6%; mean blood pressure, 124.8 ± 16.6 / 81.5 ± 9.6 mmHg). Treadmill test was performed for evaluation of chest pain. Patients with coronary artery disease, positive treadmill test result, left ventricular dysfunction or renal failure were excluded. Heart rate recovery was calculated by subtracting the HR in the first or second minute of recovery period from the HR of peak exercise (HRR1 or HRR2). Systolic blood pressure in the 4.sup.th minute of recovery stage (SBPR4) was used to show delayed blood pressure recovery. Metabolic equivalents (METs) and HR in stage 2 to 4 were significantly correlated with both HRR1 and HRR2. Multiple regression analysis of HRR revealed significant correlation of METs and SBPR4. SBPR4 was significantly correlated with both HRR1 and HRR2 (HRR1, r = -0.376, p<0.001; HRR2, r = -0.244, p = 0.008) as well as SBP in the baseline to stage 3 and pulse pressure (r = 0.406, p<0.001). Delayed BP recovery after peak exercise test revealed significant association with autonomic dysfunction and increased pulse pressure in normotensive middle-aged healthy group. It can be a simple and useful marker of autonomic dysfunction and arterial stiffness.
Journal Article
Various Substitute Aggregate Materials for Sustainable Concrete
2022
Concrete is one of the most widely used structural construction materials and has significantly influenced industrial development [...].Concrete is one of the most widely used structural construction materials and has significantly influenced industrial development [...].
Journal Article
Oxidative stress caused by activation of NADPH oxidase 4 promotes contrast-induced acute kidney injury
2018
Contrast-induced acute kidney injury (CIAKI) is a leading cause of acute kidney injury following radiographic procedures. Intrarenal oxidative stress plays a critical role in CIAKI. Nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidases (Noxs) are important sources of reactive oxygen species (ROS). Among the various types of Noxs, Nox4 is expressed predominantly in the kidney in rodents. Here, we evaluated the role of Nox4 and benefit of Nox4 inhibition on CIAKI using in vivo and in vitro models. HK-2 cells were treated with iohexol, with or without Nox4 knockdown, or the most specific Nox1/4 inhibitor (GKT137831). Effects of Nox4 inhibition on CIAKI mice were examined. Expression of Nox4 in HK-2 cells was significantly increased following iohexol exposure. Silencing of Nox4 rescued the production of ROS, downregulated pro-inflammatory markers (particularly phospho-p38) implicated in CIAKI, and reduced Bax and caspase 3/7 activity, which resulted in increased cellular survival in iohexol-treated HK-2 cells. Pretreatment with GKT137831 replicated these effects by decreasing levels of phospho-p38. In a CIAKI mouse model, even though the improvement of plasma blood urea nitrogen was unclear, pretreatment with GKT137831 resulted in preserved structure, reduced expression of 8-hydroxy-2'-deoxyguanosine (8OHdG) and kidney injury molecule-1 (KIM-1), and reduced number of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling)-positive cells. These results suggest Nox4 as a key source of reactive oxygen species responsible for CIAKI and provide a novel potential option for prevention of CIAKI.
Journal Article
Viral and Immunologic Factors Associated with Fatal Outcome of Patients with Severe Fever with Thrombocytopenia Syndrome in Korea
2021
Significant progress has been made on the molecular biology of the severe fever with thrombopenia virus (SFTSV); however, many parts of the pathophysiological mechanisms of mortality in SFTS remain unclear. In this study, we investigated virologic and immunologic factors for fatal outcomes of patients with SFTS. We prospectively enrolled SFTS patients admitted from July 2015 to October 2020. Plasma samples were subjected to SFTSV RNA RT-PCR, multiplex microbead immunoassay for 17 cytokines, and IFA assay. A total of 44 SFTS patients were enrolled, including 37 (84.1%) survivors and 7 (15.9%) non-survivors. Non-survivors had a 2.5 times higher plasma SFTSV load than survivors at admission (p < 0.001), and the viral load in non-survivors increased progressively during hospitalization. In addition, non-survivors did not develop adequate anti-SFTSV IgG, whereas survivors exhibited anti-SFTSV IgG during hospitalization. IFN-α, IL-10, IP-10, IFN-γ, IL-6, IL-8, MCP-1, MIP-1α, and G-CSF were significantly elevated in non-survivors compared to survivors and did not revert to normal ranges during hospitalization (p < 0.05). Severe signs of inflammation such as a high plasma concentration of IFN-α, IL-10, IP-10, IFN-γ, IL-6, IL-8, MCP-1, MIP-1α, and G-CSF, poor viral control, and inadequate antibody response during the disease course were associated with mortality in SFTS patients.
Journal Article