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Temperature-dependent Differences in Heading Response at Different Growth Stages of Rice
Lee, HyeonSeok,Choi, MyoungGoo,Lee, YunHo,Hwang, WoonHa,Jeong, JaeHyeok,Yang, SeoYeong,Lim, YeonHwa,Lee, ChungGen,Choi, KyungJin The Korean Society of Crop Science 2019 한국작물학회지 Vol.64 No.3
There is an increasing frequency in the occurrence of abnormal weather phenomena such as sharp increases and decreases in temperature. Under these weather conditions, the heading time of rice changes unexpectedly, which poses problems in agriculture. Therefore, we investigated the effect of temperature on the heading response at different growth stages in rice. During the period from transplanting to heading, the plants were subjected to different temperature treatments, each for a 9-day period, to observe the heading response. For the heading date analysis, "heading date" was defined as the number of days from transplanting to the appearance of the first spikelet. We found that the influence of temperature increased in the order of rooting stage, followed by meiosis, early tillering, spikelet differentiation, and panicle initiation stage in all ecological types and cultivars. In particular, unlike the results reported previously, the effect of temperature on heading during the photo-sensitive period was very small. Meanwhile, the influence of temperature on vegetative growth response at different growth stages was not consistent with heading response. These results can be used as basic data for predicting the variation in heading date owing to temperature variation at each growth stage. In addition, we propose that the concept of day length should be included in determining the influence of temperature on the photo-sensitive period.
Lee, Hyeonseok,Lee, Jong Ik,Park, Hee-Jin,Nam, Su-Yong,Kang, Moon Sung,Chun, Young Tea,Lee, Jiyoul The Electrochemical Society 2019 ECS journal of solid state science and technology Vol.8 No.11
<P>Electrochemiluminescence (ECL) based on a series of electrochemical processes of luminophores has attracted interests as a new light-emitting device platform referred to as the ECL device (ECLD). Here, we investigate the electrical and luminescence properties of ECLD with silver (Ag) electrodes. It is found that ECLD with screen-printed Ag electrodes prepared from carefully selected Ag paste ink could yield higher luminescence than that with thermally-evaporated Ag thin-film electrode. The results indicate that the low-cost large-areal printed ECLD potentially has comparable or surpassing performance to conventional vacuum-processed ECLDs.</P>
Integrated guided wave generation and sensing using a single laser source and optical fibers
Lee, Hyeonseok,Park, Hyun-Jun,Sohn, Hoon,Kwon, Il-Bum IOP Pub 2010 Measurement Science and Technology Vol.21 No.10
<P>This study proposes an integrated lead zirconate titanate/fiber Bragg grating (PZT/FBG) system that can generate and measure guided waves for structural health monitoring (SHM) using a common laser source and optical cables. Among various SHM devices used for guided wave generation and sensing, PZT transducers and FBG sensors have been widely used because of their light weight, non-intrusive nature and compactness. To take the best advantage of the merits of these SHM devices, a combination of PZT-based guided wave generation and FBG-based sensing has been attempted by some researchers. However, the existing hybrid approaches have two independent systems: a wave generation system using electrical devices and a sensing system with optical devices. We have developed a fully integrated PZT/FBG system that uses a single laser source and optical cables. This system can alleviate problems associated with conventional electrical cables, such as electromagnetic interference, signal attenuation and vulnerability to noise. A tunable laser, the common power source for guided wave generation and sensing, is modulated and amplified to excite PZT. This laser is also used with FBG sensors for measuring high-speed strain changes induced by guided waves. The feasibility of this system has been experimentally demonstrated using an aluminum plate.</P>
Design Considerations of Real-time Radar Sensor Modeling for Unmanned Surface Vehicle (USV)
Hyeonseok Lee,Hyeonhee Yi,Jung-Dong Park 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
We present a design of the real-time radar sensor model for unmanned surface vehicles (USV). To construct an efficient learning environment of an unmanned surface vehicle (USV) for the swarm operation, accurate virtual modeling of the radar sensor with a light processing load is necessary. To achieve real-time modeling of the marine radar operations with a high level of modeling accuracy under a limited computational power, our work is to extract the signal-to-clutter noise ratio (SCNR) by considering physical radar specifications with pre-extracted target radar cross-section (RCS) using a 3D-EM simulator (HFSS). Modeling of various clutters such as rain, snow, fog as well as sea clutter has been carried out for each range bin with the generated clutter matrix with Rayleigh distribution. The standard deviations of the modeled clutter were calculated with widely adopted RCS estimation formulae. Also, the signal processing unit was modeled by implementing a cell average constant false alarm rate (CA-CFAR) engine to virtualize the signal processing effects of the physical radar on filtering backscattering clutters. The presented approach on maritime radar modeling can be useful in implementing a virtual environment with less computational complexity in developing various unmanned vehicles.
Mechanical impedance measurement and damage detection using noncontact laser ultrasound.
Lee, Hyeonseok,Lim, Hyeong Uk,Hong, Jung-Wuk,Sohn, Hoon Optical Society of America 2014 Optics letters Vol.39 No.11
<P>This Letter proposes a mechanical impedance (MI) measurement technique using noncontact laser ultrasound. The ultrasound is generated by shooting a pulse laser beam onto a target structure, and its response is measured using a laser vibrometer. Once ultrasound propagation converges to structural vibration, MI is formed over the entire structure. Because noncontact lasers are utilized, this technique is applicable in harsh environments, free of electromagnetic interference, and able to perform wide-range scanning. The formation of MI and its feasibility for damage detection are verified through thermo-mechanical finite element analysis and lab-scale experiments.</P>
Lee, Habeom,Hong, Sukjoon,Lee, Jinhwan,Suh, Young Duk,Kwon, Jinhyeong,Moon, Hyunjin,Kim, Hyeonseok,Yeo, Junyeob,Ko, Seung Hwan American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.24
<P>Stretchable and transparent electronics have steadily attracted huge attention in wearable devices. Although Ag nanowire is the one of the most promising candidates for transparent and stretchable electronics, its electrochemical instability has forbidden its application to the development of electrochemical energy devices such as supercapacitors. Here, we introduce a highly stretchable and transparent super capacitor based on electrochemically stable Ag Au core shell nanowire percolation network electrode. We developed a simple solution process to synthesize the Ag Au core shell nanowire with excellent electrical conductivity as well as greatly enhanced chemical and electrochemical stabilities compared to pristine Ag nanowire. The proposed core shell nanowirebased supercapacitor still possesses fine optical transmittance and outstanding mechanical stability up to 60% strain. The Ag Au core shell nanowire can be a strong candidate for future wearable electrochemical energy devices.</P>
( Hyeonseok Kim ),( Jeong Ha Mok ),( Bohyoung Kang ),( Taehoon Lee ),( Hyun-kyung Lee ),( Hang Jea Jang ),( Yu Ji Cho ),( Doosoo Jeon ) 대한내과학회 2019 The Korean Journal of Internal Medicine Vol.34 No.2
Background/Aims: This study was conducted to evaluate the recent prevalence and trend of anti-tuberculosis (TB) drug resistance with a focus on multidrug-resistance (MDR) and fluoroquinolone resistance in South Korea. Methods: We retrospectively reviewed the drug susceptibility testing results of culture-confirmed Mycobacterium tuberculosis isolates collected from 2010 to 2014 at seven tertiary hospitals in South Korea. Results: A total of 5,599 cases were included: 4,927 (88.0%) were new cases and 672 (12.0%) were previously treated cases. The MDR rate has significantly decreased from 6.0% in 2010 to 3.0% in 2014 among new cases, and from 28.6% in 2010 to 18.4% in 2014 among previously treated cases (p < 0.001 and p = 0.027, respectively). The resistance rate to any f luoroquinolone was 0.8% (43/5,221) in non-MDR-TB patients, as compared to 26.2% (99/378) in MDR-TB patients (p < 0.001). There was no significant change in the trend of fluoroquinolone resistance among both non- MDR-TB and MDR-TB patients. Among the 43 non-MDR-TB patients with fluoroquinolone resistance, 38 (88.4%) had fluoroquinolone mono-resistant isolates. Conclusions: The prevalence of MDR-TB has significantly decreased from 2010 to 2014. The prevalence of fluoroquinolone resistance among non-MDR-TB patients was low, but the existence of fluoroquinolone mono-resistant TB may be a warning on the widespread use of fluoroquinolone in the community.
Damage detection for pipeline structures using optic-based active sensing
Lee, Hyeonseok,Sohn, Hoon Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.5
This study proposes an optics-based active sensing system for continuous monitoring of underground pipelines in nuclear power plants (NPPs). The proposed system generates and measures guided waves using a single laser source and optical cables. First, a tunable laser is used as a common power source for guided wave generation and sensing. This source laser beam is transmitted through an optical fiber, and the fiber is split into two. One of them is used to actuate macro fiber composite (MFC) transducers for guided wave generation, and the other optical fiber is used with fiber Bragg grating (FBG) sensors to measure guided wave responses. The MFC transducers placed along a circumferential direction of a pipe at one end generate longitudinal and flexural modes, and the corresponding responses are measured using FBG sensors instrumented in the same configuration at the other end. The generated guided waves interact with a defect, and this interaction causes changes in response signals. Then, a damage-sensitive feature is extracted from the response signals using the axi-symmetry nature of the measured pitch-catch signals. The feasibility of the proposed system has been examined through a laboratory experiment.