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Orthogonal Waveform Space Projection Method for Adaptive Jammer Suppression
Kang-In Lee,Hojun Yoon,Jongmann Kim,Young-Seek Chung 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.2
In this paper, we propose a new jammer suppression algorithm that uses orthogonal waveform space projection (OWSP) processing for a multiple input multiple output (MIMO) radar system exposed to a jamming signal. Generally, a conventional suppression algorithm based on adaptive beamforming (ABF) needs a covariance matrix composed of the jammer and noise only. By exploiting the orthogonality of the transmitting waveforms of MIMO, we can construct a transmitting waveform space (TWS). Then, using the OWSP processing, we can build a space orthogonal to the TWS that contains no SOI. By excluding the SOI from the received signal, even in the case that contains the SOI and jamming signal, the proposed algorithm makes it possible to evaluate the covariance matrix for ABF. We applied the proposed OWSP processing to suppressing the jamming signal in bistatic MIMO radar. We verified the performance of the proposed algorithm by comparing the SINR loss to that of the ideal covariance matrix composed of the jammer and noise only. We also derived the computational complexity of the proposed algorithm and compared the estimation of the DOD and DOA using the SOI with those using the generalized likelihood ratio test (GLRT) algorithm.
Splenic Autotransplantation after Blunt Spleen Injury in Children
( Hojun Lee ),( Byung Hee Kang ),( Junsik Kwon ),( John Cook-jong Lee ) 대한외상학회 2018 대한외상학회지 Vol.31 No.2
Non-operative management has been preferred in blunt spleen injury. Moreover children are more susceptible to post-splenectomy infection, spleen should be preserved if possible. However, splenectomy is inevitable to patients with severe splenic injury. Therefore splenic autotransplantation could be the last chance for preserving splenic function in these patients although efficacy has not proven. Here we reported four cases of children who were underwent splenic autotransplantation successfully after blunt trauma.
Ridge-following control for agricultural tractors using deep learning and stereo camera
Hojun Kang,Dongoh Seo,Beomjin Lee,Jong-Gyu Han,Jun-Hee Jo,Mooncheol Won 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7
The furrow irrigation, which forms a ridge-furrow and grows several crops on the ridge, involves the seeding work using the tractor that follows the path of the ridge. This work requires long hours labor from human, and there is a possibility that the work efficiency may decrease. In this paper, we propose deep learning and stereo image-based algorithms for sowing tasks on ridges via autonomous path-following of the tractor. The collected stereo image is converted into a depth image through a matching algorithm, and the depth image is input to a MobileNetV2-based deep learning network model to obtain a center line of the ridge. In addition, the target value of steering angle control is calculated by waypoint preview control concept. so that the tractor can follow the estimated center line of the ridge. The proposed algorithm is verified by GPS-based path information of autonomous driving and comparing it with human-operated driving path.
양지훈,Kang Donggu,An SangHyun,Ryu Jeong Yeop,Lee KyoungHo,Kim Jun Sik,Song Moon-Yong,Kim Young-Sik,Kwon Sang-Mo,Jung Won-Kyo,Jeong Woonhyeok,Jeon Hojun 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
Until recent, there are no ideal small diameter vascular grafts available on the market. Most of the commercialized vascular grafts are used for medium to large-sized blood vessels. As a solution, vascular tissue engineering has been introduced and shown promising outcomes. Despite these optimistic results, there are limitations to commercialization. This review will cover the need for extrusion-based 3D cell-printing technique capable of mimicking the natural structure of the blood vessel. First, we will highlight the physiological structure of the blood vessel as well as the requirements for an ideal vascular graft. Then, the essential factors of 3D cell-printing including bioink, and cell-printing system will be discussed. Afterwards, we will mention their applications in the fabrication of tissue engineered vascular grafts. Finally, conclusions and future perspectives will be discussed.
ReRAM 소자의 비정질물질 Ag도핑에 따른 특성 향상에 대한 연구
김강(Kang Kim),이호준(Hojun Lee) 산업기술교육훈련학회 2021 산업기술연구논문지 (JITR) Vol.26 No.2
The most popular devices in next-generation computer memory technology are the phase change RAM (PRAM), nano-floating gate memory (NFGM), resistance RAM (ReRAM), polymer RAM (PoRAM), magnetic RAM (MRAM), and molecular electronic devices. Amongst these, ReRAM is the most-researched candidate for nonvolatile memory technologies due to its simple metal-insulator-metal (MIM) structure and excellent operational characteristics. However, it faces obstacles such as high production costs and insufficient uniformity. This study aims to tackle the latter problem by spin-coating Ag nanoparticles on the upper electrode to improve the uniformity characteristics.