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전민기 ( Jeon¸ Min-gi ),남원호 ( Nam¸ Won-ho ),양미혜 ( Yang¸ Mi-hye ),문영식 ( Mun¸ Young-sik ),홍은미 ( Hong¸ Eun-mi ),옥정훈 ( Ok¸ Jung-hun ),황선아 ( Hwang¸ Seonah ),허승오 ( Hur¸ Seung-oh ) 한국농공학회 2021 한국농공학회논문집 Vol.63 No.5
Soil moisture plays a critical role in hydrological processes, land-atmosphere interactions and climate variability. It can limit vegetation growth as well as infiltration of rainfall and therefore very important for agriculture sector and food protection. Recently, due to the increased damage from drought caused by climate change, there is a frequent occurrence of shortage of agricultural water, making it difficult to supply and manage stable agricultural water. Efficient water management is necessary to reduce drought damage, and soil moisture management is important in case of upland crops. In this study, soil moisture was calculated based on the water balance model, and the suitability of soil moisture data was verified through the application. The regional soil moisture was calculated based on the meteorological data collected by the meteorological station, and applied the Runs theory. We analyzed the spatiotemporal variability of soil moisture and drought impacts, and analyzed the correlation between actual drought impacts and drought damage through correlation analysis of Standardized Precipitation Index (SPI). The soil moisture steadily decreased and increased until the rainy season, while the drought size steadily increased and decreased until the rainy season. The regional magnitude of the drought was large in Gyeonggi-do and Gyeongsang-do, and in winter, severe drought occurred in areas of Gangwon-do. As a result of comparative analysis with actual drought events, it was confirmed that there is a high correlation with SPI by each time scale drought events with a correlation coefficient.
Investigation for Manufacture of the Portable Backscattering Mössbauer Spectrometer
Mingi Eom,Young Rang Uhm,Jaegi Lee,Gwang-Min Sun 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1
Mössbauer spectroscopy is one of the most powerful methods for the analysis of hyperfine interactions in materials. The most widely used target material is <sup>57</sup>Fe, of which the natural abundance is 2.12 % [1]. As the γ-ray emitted from the first excited state of <sup>57</sup>Fe has too low energy (14.4 keV) to penetrate a thick sample, the transmission Mössbauer spectrometer can analyze the only artificial thin samples. To analyze cultural heritages or relics, non-destructive (without sampling) and in situ inspection is required. The backscattering Mössbauer spectrometer detects the backscattered γ-rays from the surface of the materials, so the additional sampling is unnecessary. An example of this type of Mössbauer spectrometer is shown in Figure 1. For the in situ measurement, miniaturized devices, including a velocity drive and detectors, should be developed. The Miniaturized Mössbauer Spectrometer (MIMOS Ⅱ) was developed and sent to MARS by NASA, which was the type of backscattering Mössbauer spectrometer [2]. In the first step of developing the velocity transducer, the interested velocity range is from -10 to 10 mm/s with a triangular waveform. Then the time term per signal will be set constant so that the whole channel number becomes 1,024. As shown in Figure 1, detectors should be attached to the head of the spectrometer, and more than one detector is required to get a higher count rate. The previous detectors for the transmission Mössbauer spectrometer were gas detectors or scintillators, which are not suitable for portable devices. The first prototype is shown in Figure 2. The Si-PIN detectors, also used in the MIMOS Ⅱ, were equipped in the front line of the velocity transducer. Our new spectrometer will be equipped with cadmium telluride (CdTe) semiconductor detectors. The CdTe detectors can detect 6.3 and 14.4 keV photons from <sup>57</sup>Fe atoms with the full width at half maximum (FWHM) of 500 eV at 14.4 keV and have higher sensitivity than Si-PIN detectors at energies above 20 keV [3]. A newly developed Mössbauer spectrometer will be applied to the investigation of metal and ceramic relics.
Gait Programming of Quadruped Bionic Robot
Mingying Li,Chengbiao Jia,이응주,Yiran Feng 한국멀티미디어학회 2021 The journal of multimedia information system Vol.8 No.2
Foot bionic robot could be supported and towed through a series of discrete footholds and be adapted to rugged terrain through attitude adjustment. The vibration isolation of the robot could decouple the fuselage from foot-end trajectories, thus, the robot walked smoothly even if in a significant terrain. The gait programming and foot end trajectory algorithm were simulated. The quadruped robot of parallel five linkages with eight degrees of freedom were tested. The kinematics model of the robot was established by setting the corresponding coordinate system. The forward and inverse kinematics of both supporting and swinging legs were analyzed, and the angle function of single leg driving joint was obtained. The trajectory planning of both supporting and swinging phases was carried out, based on the control strategy of compound cycloid foot-end trajectory planning algorithm with zero impact. The single leg was simulated in Matlab with the established kinematic model. Finally, the walking mode of the robot was studied according to bionics principles. The diagonal gait was simulated and verified through the foot-end trajectory and the kinematics.