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A Study on Ship Path Following System Utilizing a Small Model Boat
Wonjin CHOI(최원진),Serng Bae MOON(문성배) 한국수산해양교육학회 2024 水産海洋敎育硏究 Vol.36 No.1
This study introduces a ship path following system achieved through the design of a course controller based on the ships maneuvering model. Both simulations and experiments were conducted to validate the systems effectiveness. The ships maneuvering model was identified by applying an ARX (Auto-Regression with eXtra input) model, representing the system model based on input-output data. The course controller employed PD (Proportional-Derivative) controller, recognized for its simplicity and excellent control performance. Prior to sea experiments, the effectiveness of the ships maneuvering model and course controller was verified through simulation. Subsequently, sea experiments were conducted using a small model boat. The path following results in real sea conditions revealed a maximum cross track distance (XTD) of approximately 3.4 m (3.7 L) for the experimental boat, indicating successful path following along the predefined route.
A Basic Study on Connected Ship Navigation System
Wonjin Choi,Seung-Hwan Jun 한국항해항만학회 2020 한국항해항만학회지 Vol.44 No.2
Maritime autonomous surface ships (MASS) has been developed over the years. But, there are many unresolved problems. To overcome these problems, this study proposes connected ship navigation system. The system comprises a slave ship and a master ship that leads the slave ship. To implement this system, communication network, route planning algorithms, and controllers are designed. The communication network is built using the transmission control protocol/Internet protocol (TCP/ IP) socket communication method to exchange data between ships. The route planning algorithms calculate the course and distance of the slave ship using the middle latitude sailing method. Nomoto model is used as the mathematical model of the slave ship maneuvering motion. Then, the autoregressive with exogenous variables (ARX) model is used to estimate the parameters of Nomoto model. Based on the above model, the automatic steering controller is designed using a proportional-derivative (PD) control. Also, the speed controller is designed for the slave ship to maintain constant distance from the master ship. Sea experiments are conducted to verify the proposed system with two remodeled boats.
Choi, Wonjin,Lee, Ingeun,Choi, EunMi Institute of Electrical and Electronics Engineers 2017 IEEE transactions on electron devices Vol.64 No.7
<P>The sine waveguide slow-wave structure is a promising interaction circuit for traveling-wave tubes in the terahertz region because it possesses advantageous properties such as high transmission, easy fabrication, and elimination of the electron beam tunnel. These waveguides could be fabricated by nanocomputer numerical control (CNC) machining, a fabrication method capable of fabricating microscale components. In our study, we evaluate the practical feasibility of manufacturing 300-GHz sine waveguides with the ideal design, using nano-CNC machining. It is found that the ideal sine waveguide circuit must be modified, because of the limitations imposed by the actual tool size of the nano-CNC machine. Simulations of cold-and hot-tests of the circuit-including the electron beam effect-were conducted for both the ideal and the modified sine waveguide circuits. A modified sine waveguide was successfully machined using a nano-CNC machine with a 0.12-mm diameter tool tip. The S-parameters of the fabricated circuit were measured and compared to simulation data. A detailed analysis of the measured transmission loss was performed, and this loss was found to be attributable to a gap left by the assembly process between the two copper plates.</P>
Two-terminal mechanical perovskite/silicon tandem solar cells with transparent conductive adhesives
Choi, In Young,Kim, Chan Ul,Park, Wonjin,Lee, Hyungmin,Song, Myoung Hoon,Hong, Kuen Kee,Seok, Sang Il,Choi, Kyoung Jin Elsevier 2019 Nano energy Vol.65 No.-
<P><B>Abstract</B></P> <P>Herein, we demonstrate a novel two-terminal perovskite/silicon mechanical tandem solar cell, fabricated by bonding a silicon cell upside down on a perovskite cell using a transparent conductive adhesive (TCA). The TCA consists of Ag-coated poly(methyl 2-methylpropenoate) microparticles embedded in a polymer adhesive. The Ag microparticles serve as an electrical current path, and the polymer adhesive mechanically bonds two sub-cells. The specific contact resistance and transmittance of the TCA layer were determined to be 5.46 × 10<SUP>−2</SUP> Ω∙cm<SUP>2</SUP> and >97.0%, respectively. Through an optical simulation, the current of the perovskite top cell was predicted to match the current of the p-type Si bottom cell with an Al back-surface field (BSF) layer when the thickness of MAPbI3 was 150 nm. The tandem cell fabricated under the optimal current matching conditions exhibited a current density of 15.43 mA cm-2, an open-circuit voltage of 1.59 V, and a fill factor of 79%, resulting in a steady-state efficiency of 19.4%. To the best of our knowledge, our result is the highest efficiency among two-terminal mechanical perovskite/silicon tandem cells. The unique structure of this tandem cell facilitates an excellent long-term stability without encapsulation in humid environment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel idea to fabricate a two-terminal mechanical tandem solar cell by using a transparent conductive adhesives. </LI> <LI> Transparent conductive adhesives make the commercial textured silicon cells easily be tandemized with perovskite cells. </LI> <LI> Optical simulation for current matching of two sub-cells. </LI> <LI> We propose strategies to achieve a higher efficiency (>24%) through PERC silicon cells and band-gap-tuned perovskite cells. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Choi, Seunghwan,Kim, Joohwan,Kim, Ji-Hee,Lee, Dong-Keon,Park, Wonjin,Park, Minsik,Kim, Suji,Hwang, Jong Yun,Won, Moo-Ho,Choi, Yoon Kyung,Ryoo, Sungwoo,Ha, Kwon-Soo,Kwon, Young-Guen,Kim, Young-Myeong Nature Publishing Group 2017 Experimental and molecular medicine Vol.49 No.11
<P>Heme oxygenase-1-derived carbon monoxide prevents inflammatory vascular disorders. To date, there is no clear evidence that HO-1/CO prevents endothelial dysfunction associated with the downregulation of endothelial NO synthesis in human endothelial cells stimulated with TNF-α. Here, we found that the CO-releasing compound CORM-2 prevented TNF-α-mediated decreases in eNOS expression and NO/cGMP production, without affecting eNOS promoter activity, by maintaining the functional activity of the <I>eNOS</I> mRNA 3′-untranslated region. By contrast, CORM-2 inhibited MIR155HG expression and miR-155-5p biogenesis in TNF-α-stimulated endothelial cells, resulting in recovery of the 3′-UTR activity of <I>eNOS</I> mRNA, a target of miR-155-5p. The beneficial effect of CORM-2 was blocked by an NF-κB inhibitor, a miR-155-5p mimic, a HO-1 inhibitor and siRNA against HO-1, indicating that CO rescues TNF-α-induced eNOS downregulation through NF-κB-responsive miR-155-5p expression via HO-1 induction; similar protective effects of ectopic HO-1 expression and bilirubin were observed in endothelial cells treated with TNF-α. Moreover, heme degradation products, except iron and <I>N</I>-acetylcysteine prevented H<SUB>2</SUB>O<SUB>2</SUB>-mediated miR-155-5p biogenesis and eNOS downregulation. These data demonstrate that CO prevents TNF-α-mediated eNOS downregulation by inhibiting redox-sensitive miR-155-5p biogenesis through a positive forward circuit between CO and HO-1 induction. This circuit may play an important preventive role in inflammatory endothelial dysfunction associated with human vascular diseases.</P>
인공어초 형상과 재질 및 수온에 따른 전복(Haliotis discus hannai, abalone)의 선호도
최원진(WonJin CHOI),이석형(Sukhyung LEE),권인영(Inyeong KWON),김태호(Taeho KIM) 전남대학교 어업기술연구소 2020 어업기술연구소보고지 Vol.13 No.1
This study was conducted to examine preference of abalone according to artificial reef shapes, materials and change of water temperatures for seeking artificial reef shape and characteristics of abalone movement. Physical factors were restricted to artificial reef shapes (rectangle, circle and triangle), materials (porus cement mortar, cement mortar), water temperatures (10, 15 and 20℃) and focused on the characteristics of abalone movement when they seek the suitable artificial reef shapes and materials. A series of experiments were conducted in a recirculation aquaculture system with dimensions of 2100×1000×1100 mm. 30 abalones (sizes: 3.3 ± 5.1 g) were used for each experiment. The experiments were replicated 3 times at (10, 15 and 20℃) The preference artificial reef shapes, materials and characteristics of abalone movement were observed using video (24 hours) and naked eye (12 hours three times Am09:00, Pm13:30, Pm18:00) a day) The data were evaluated by an analysis of variance (ANOVA). Behavior analysis was analyzed through observation log and video. It was observed that The numbers of abalones attracted porus cement mortar than cement mortar. At 10°C, they clustered in cement by a margin of 0.8 times, but at 15°C they clustered in porous cement by a margin of 2.8 times and a difference of 4.2 times at 20°C. also attracted triangle hole shape than circle and rectangle hole shape. The moving distance (avg. 1.35 m) and speed (avg. 0.033 10<SUP>-3</SUP> m/s) of abalone showed highest activity at water temperature at 15℃.