Spin Circuit Model for Materials with Spin-Momentum Locking

Seokmin Hong 한국자기학회 2017 한국자기학회 학술연구발표회 논문개요집 Vol.2017 No.11

Improving Wind Speed Forecasts Using Deep Neural Network

Seokmin Hong,SungKwan Ku 국제문화기술진흥원 2019 International Journal of Advanced Culture Technolo Vol.7 No.4

Wind speed data constitute important weather information for aircrafts flying at low altitudes, such as drones. Currently, the accuracy of low altitude wind predictions is much lower than that of high-altitude wind predictions. Deep neural networks are proposed in this study as a method to improve wind speed forecast information. Deep neural networks mimic the learning process of the interactions among neurons in the brain, and it is used in various fields, such as recognition of image, sound, and texts, image and natural language processing, and pattern recognition in time-series. In this study, the deep neural network model is constructed using the wind prediction values generated by the numerical model as an input to improve the wind speed forecasts. Using the ground wind speed forecast data collected at the Boseong Meteorological Observation Tower, wind speed forecast values obtained by the numerical model are compared with those obtained by the model proposed in this study for the verification of the validity and compatibility of the proposed model.

Improving Wind Speed Forecasts Using Deep Neural Network

Hong, Seokmin,Ku, SungKwan The International Promotion Agency of Culture Tech 2019 International Journal of Advanced Culture Technolo Vol.7 No.4

Wind speed data constitute important weather information for aircrafts flying at low altitudes, such as drones. Currently, the accuracy of low altitude wind predictions is much lower than that of high-altitude wind predictions. Deep neural networks are proposed in this study as a method to improve wind speed forecast information. Deep neural networks mimic the learning process of the interactions among neurons in the brain, and it is used in various fields, such as recognition of image, sound, and texts, image and natural language processing, and pattern recognition in time-series. In this study, the deep neural network model is constructed using the wind prediction values generated by the numerical model as an input to improve the wind speed forecasts. Using the ground wind speed forecast data collected at the Boseong Meteorological Observation Tower, wind speed forecast values obtained by the numerical model are compared with those obtained by the model proposed in this study for the verification of the validity and compatibility of the proposed model.

Viewing Angle-Improved 3D Integral Imaging Display with Eye Tracking Sensor

Hong, Seokmin,Shin, Donghak,Lee, Joon-Jae,Lee, Byung-Gook The Korea Institute of Information and Commucation 2014 Journal of information and communication convergen Vol.12 No.4

In this paper, in order to solve the problems of a narrow viewing angle and the flip effect in a three-dimensional (3D) integral imaging display, we propose an improved system by using an eye tracking method based on the Kinect sensor. In the proposed method, we introduce two types of calibration processes. First process is to perform the calibration between two cameras within Kinect sensor to collect specific 3D information. Second process is to use a space calibration for the coordinate conversion between the Kinect sensor and the coordinate system of the display panel. Our calibration processes can provide the improved performance of estimation for 3D position of the observer's eyes and generate elemental images in real-time speed based on the estimated position. To show the usefulness of the proposed method, we implement an integral imaging display system using the eye tracking process based on our calibration processes and carry out the preliminary experiments by measuring the viewing angle and flipping effect for the reconstructed 3D images. The experimental results reveal that the proposed method extended the viewing angles and removed the flipping images compared with the conventional system.

Fusion of point cloud and integral-imaging concept for focal plane variable 3D display

Seokmin Hong(홍석민),Hyunmin Kang(강현민),Hyunju Oh(오현주),Jiyong Park(박지용) 한국컴퓨터그래픽스학회 2022 한국컴퓨터그래픽스학회 학술대회 Vol.2022 No.7

Effects of the Alloy Design and Fabrication Process on Mechanical Properties of Mo + V-Added SA508 Gr.1A Steel for Main Steam Line Piping in Nuclear Power Plants

Seokmin Hong,Se‑Mi Hyun,Jongmin Kim,Yo‑Seob Lee,Maan‑Won Kim,Min‑Chul Kim 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3

To apply the leak-before-break (LBB) design to main steam line (MSL) piping in nuclear power plants, higher strength andrelatively tough SA508 Gr.1A steel were developed by changing the alloy design and fabrication process. Two actual-sizeprototype types of MSL piping (M1 and M2) with different contents of C, Mo, and V were fabricated and their mechanicalproperties were evaluated and compared with those of commercial SA508 Gr.1A steel. In the alloy design, the content ofC was decreased to reduce the degree to which cementite deteriorated the toughness, and Mo and V were added to increasethe strength by forming bainite and VC precipitates. During the fabrication process, the thickness of the MSL piping wasminimized by rough machining before a heat treatment to increase the strength by increasing the cooling rate during quenching. Both prototype steels had better strength and toughness than commercial steel. In particular, the mechanical propertiesof M2 with lower alloy contents had a good combination of strength and toughness. The yield strength, USE, and JIcof M2were 407 MPa, 393 J and 680 kJ/m2 at 286 °C, respectively, which were increased by 167 MPa, 90 J, and 98 kJ/m2 comparedto the correspondingly parameters of commercial steel. The LBB margin of MSL piping using M2 steels was 1.49, whichwas a 30% higher than those using commercial steels.

High Temperature Sliding Wear Behaviour of Ti6Al4V Thermal Oxidised for Different Oxidation Durations

Seokmin Hong,Se‑Mi Hyun,Jongmin Kim,Jongmin Kim,Yo‑Seob Lee,Maan‑Won Kim,Min‑Chul Kim 대한금속ᆞ재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

To apply the leak-before-break (LBB) design to main steam line (MSL) piping in nuclear power plants, higher strength andrelatively tough SA508 Gr.1A steel were developed by changing the alloy design and fabrication process. Two actual-sizeprototype types of MSL piping (M1 and M2) with different contents of C, Mo, and V were fabricated and their mechanicalproperties were evaluated and compared with those of commercial SA508 Gr.1A steel. In the alloy design, the content ofC was decreased to reduce the degree to which cementite deteriorated the toughness, and Mo and V were added to increasethe strength by forming bainite and VC precipitates. During the fabrication process, the thickness of the MSL piping wasminimized by rough machining before a heat treatment to increase the strength by increasing the cooling rate during quenching. Both prototype steels had better strength and toughness than commercial steel. In particular, the mechanical propertiesof M2 with lower alloy contents had a good combination of strength and toughness. The yield strength, USE, and JIcof M2were 407 MPa, 393 J and 680 kJ/m2 at 286 °C, respectively, which were increased by 167 MPa, 90 J, and 98 kJ/m2 comparedto the correspondingly parameters of commercial steel. The LBB margin of MSL piping using M2 steels was 1.49, whichwas a 30% higher than those using commercial steels.

Real-Time Walking Pattern Generation Method for Humanoid Robots by Combining Feedback and Feedforward Controller

Seokmin Hong,Yonghwan Oh,Doik Kim,Bum-Jae You Institute of Electrical and Electronics Engineers 2014 IEEE transactions on industrial electronics Vol. No.

<P>This paper focuses on real-time walking pattern generation for humanoid robots with linear inverted pendulum model (LIPM). In general, there are many issues in generating proper walking patterns of center of mass and zero moment point (ZMP) with the LIPM since the LIPM has two drawbacks such as instability and non-minimum phase property. For resolving these difficulties, the paper proposes a new real-time approach by combining a feedback and a feedforward controller. The feedback controller employs a pole placement method which shifts the poles of the LIPM in order to improve system stability. The feedforward controller utilizes advanced pole-zero cancelation by series approximation method (APZCSA) for reducing non-minimum phase property which occurs by an unstable zero and is not able to be dealt with by the feedback controller. In addition, the APZCSA improves the tracking error induced by finite series approximation. Using the two controllers, the proposed method makes the transfer function of overall walking pattern generation system approximately unity and consequently generates a stable walking pattern which follows a desired ZMP according to walking path. The efficiency of the proposed method is verified by walking pattern planning examples and experiments with the humanoid robot MAHRU-R.</P>

GPU-accelerated integral imaging and full-parallax 3D display using stereo–plenoptic camera system

Hong, Seokmin,Incardona, Nicolò,Inoue, Kotaro,Cho, Myungjin,Saavedra, Genaro,Martinez-Corral, Manuel Elsevier 2019 Optics and lasers in engineering Vol.115 No.-

<P><B>Abstract</B></P> <P>In this paper, we propose a novel approach to produce integral images ready to be displayed onto an integral-imaging monitor. Our main contribution is the use of commercial plenoptic camera, which is arranged in a stereo configuration. Our proposed set-up is able to record the radiance, spatial and angular, information simultaneously in each different stereo position. We illustrate our contribution by composing the point cloud from a pair of captured plenoptic images, and generate an integral image from the properly registered 3D information. We have exploited the graphics processing unit (GPU) acceleration in order to enhance the integral-image computation speed and efficiency. We present our approach with imaging experiments that demonstrate the improved quality of integral image. After the projection of such integral image onto the proposed monitor, 3D scenes are displayed with full-parallax.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The use of a stereo–plenoptic camera system. </LI> <LI> Novel for the composing sub-aperture image array from captured plenoptic image and calculate dense depth map. </LI> <LI> Compose a point cloud and registration between a pair of 3D data. </LI> <LI> Generate 3D image (integral image) from composed voxel in virtual 3D space. </LI> <LI> Display 3D images into integral imaging monitor with great parallax and viewing angle. </LI> </UL> </P>

Effects of Microstructural Variation on Charpy Impact Properties in Heavy-Section Mn-Mo-Ni Low Alloy Steel for Reactor Pressure Vessel

Seokmin Hong,Jaemin Song,김민철,Kwon-Jae Choi,Bong-Sang Lee 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.2

The effects of microstructural changes in heavy-section Mn-Mo-Ni low alloy steel on Charpy impact properties were investigated using a 210 mm thick reactor pressure vessel. Specimens were sampled from 5 different positions at intervals of 1/4 thickness from the inner surface to the outer surface. A detailed microstructural analysis of impact-fractured specimens showed that coarse carbides along the lath boundaries acted as fracture initiation sites, and cleavage cracks deviated at prior-austenite grain boundaries and bainite lath boundaries. Upper shelf energy was higher and energy transition temperature was lower at the surface positon, where fine bainitic microstructure with homogeneously distributed fine carbides were present. Toward the center, coarse upper bainite and precipitation of coarse inter-lath carbides were observed, which deteriorated impact properties. At the 1/4T position, the Charpy impact properties were worse than those at other positions owing to the combination of elongated-coarse inter-lath carbides and large effective grain size.