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Combined Sensor–Sensorless Control of PMDC Motor for HD Camera of Unmanned Monitoring System
Dong‑Hee Lee 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1
This paper presents a position control scheme for a high-defnition serial digital interface (HD-SDI) camera of an unmanned monitoring system. A combination of both sensor and sensorless algorithms of a permanent magnet (PM) DC motor is proposed to create smooth camera movements, stop it at desired positions, and obtain high-quality images without shaking. The back EMF of the motor can be estimated and its actual speed can be calculated accurately by using a model reference adaptive sensorless (MRAS) method. A low-resolution hall sensor is used to approximate the speed instead of measuring the actual value. The moving position can be estimated from the speed approximation and it can be used together with a sliding mode observer to modify the back EMF constant. In the advanced position control of the camera, both instantaneous speed and moving position references are determined by the acceleration and deceleration speed patterns to satisfy the dynamic response during operation. Furthermore, the instantaneous position error can be compensated by incorporating a speed reference. The efectiveness of the proposed control scheme was verifed through experiments.
Phylogenetic Analysis of the HIV-1 nef Gene from Korean Isolates
Dong-HunLee,YeupYoon,Chan-HeeLee 한국미생물학회 2003 The journal of microbiology Vol.41 No.3
Previous phylogenetic studies on human immunodeficiency virus type 1 (HIV-1) isolated from Korean patients suggest that the major subtype of Korean isolate is subtype B. In this subtype, some of the Korean isolates seem to be clustered exclusively of foreign isolates. Presence of this so-called “Korean clade” among Korean isolates is unique but needs verification since the number of Korean isolates used in previous studies was limited. This study aimed to identify the presence of the “Korean clade” by molecular phylogenetic analysis using all the Korean nef gene sequences registered in the NCBI GenBank (N=243) together with 32 reference strains and 77 foreign isolates. Extensive analysis of the nef gene nucleotide sequences by neighbor-joining method revealed the following. Most (83.1%) of the Korean isolates belonged to subtype B, and 81.2% of subtype B were clustered together and excluded foreign isolates (bootstrap value=91.9%). Within Korean subtype B cluster, no characteristic subcluster formation was evident since the bootstrap values for the subcluster were very low. Due to limited information, the phylogenetic analysis failed to identify the epidemiological linkage among specific groups such as homosexuals and hemophiliacs within the Korean subtype B cluster. Detailed analysis and epidemiological information are needed to clarify the origin and significance of the Korean subtype B cluster.
조동규,우상현,Jungil Yang,Dong-HeeLee,임유성,Daekuk Kim,Sungmin Park,이문석 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.4
In this work, we investigated the enhanced performance of IZO-based TFTs with HfSiOx gate insulators. Four types of HfSiOx gate insulators with different deposition powers were deposited by co-sputtering HfO2and Si. To simplify the processing sequences, all of the layers of the TFTs were deposited by an RF-magnetron sputtering method using patterned shadow-masks without any intentional heating of the substrate or subsequent thermal annealing. The four different HfSiOx structural properties were investigated by x-ray Diffraction (XRD),Atomic Force Microscopy (AFM), and the electrical characteristics were also analyzed. There were some noticeable differences depending on the composition of the HfO2 and Si combination. The TFT based on the HfSiOx gate insulator comprised of HfO2 (100 W)-Si (100 W) showed the best results with a field effect mobility of 2.0 cm2/V·s, a threshold voltage of 0.6 V, an Ion/off ratio of 3.18 × 105, and an insulator surface roughness of 0.16 nm RMS. This confirms that the composition of the HfO2 and Si is an important factor in an HfSiOx insulator. In addition, the effective bonding of the HfO2 and Si reduced the defects in the insulator bulk and also improved the interface quality between the channel and the gate insulator