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Ko, Ok Hyun,Hong, Joon Hee Informa UK (TaylorFrancis) 2009 Nucleosides, nucleotides & nucleic acids Vol.28 No.8
<P>The first synthetic route of novel 2'(beta),3'(beta)-C-dimethyl carbodine analogues is described. The key intermediate cyclopentenyl alcohol 11(beta) prepared from Weinreb amide 4 via ring-closing metathesis (RCM) and vicinal dihydroxylation. Coupling of 12 with nucleosidic bases via the Pd(0) catalyzed reaction followed by stereoselective dihydoxylation and deprotection afforded the target carbocyclic nucleoside analogues. The synthesized compounds were evaluated as inhibitors of the hepatitis C virus (HCV) in Huh-7 cell line in vitro. However, the nucleosides failed to inhibit HCV RNA replication in the cell-based replicon assay (EC(50) > muM).</P>
Kookhyun Kim,Sungju Park,Sangjoong Lee,Seongjun Hwang,Sumin Kim,Yonghee Lee 한국해양공학회 2020 韓國海洋工學會誌 Vol.34 No.6
Composite materialsuch as glass-fiber reinforced plastic and carbon-fiber reinforced plastic (CFRP) shows anisotropic property and have been widely used for structural members and outfitings of ships. The structural safety of composite structures has been generally evaluated via finite element analysis. This paper presents a technique for updating the finite element model of anisotropic beams or plates via natural frequencies. The finite element model updates involved a compensation process of anisotropic material properties, such as the elastic and shear moduli of orthotropic structural members. The technique adopted was based on a discrete genetic algorithm, which is an optimization technique. The cost function was adopted to assess the optimization problem, which consisted of the calculated and referenced low-order natural frequencies for the target structure. The optimization process was implemented with MATLAB, which includes the finite element updates and the corresponding natural frequency calculations with MSC/NASTRAN. Material properties of a virtual cantilevered orthotropic beam were estimated to verify the presented method and the results obtained were compared with the reference values. Furthermore, the technique was applied to a cantilevered CFRP beam to successfully estimate the unknown material properties.
Kookhyun Kim 한국해양공학회 2021 韓國海洋工學會誌 Vol.35 No.3
The survivability of a naval ship is the ability of the ship and its onboard systems to remain functional and continue a designated mission in man-made hostile environments. A passive decoy system is primarily used as a weapon system for improving the survivability of a naval ship. In this study, an engagement scenario-based simulation program was developed for decoy effectiveness assessments against an anti-ship missile (ASM), which tracks a target with sea-skimming and active radar homing. The program can explain the characteristics of a target ship, such as the radar cross section and evasive maneuvers, as well as the operational performance of the onboard decoy system, the guidance method of the ASM, and the engagement environment’s wind speed and direction. This paper describes the theory and formulations, configuration, and user interface of the developed program. Numerical examples of a decoy effect assessment of a virtual naval ship against an ASM are presented.
김국현(Kookhyun Kim) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.4
The independent component analysis (ICA) technique is a source identification method that uses statistical independence to separate source signals from measured signals. It has been succesfully applied to various fields such as medical care and communication. In this study, the ICA technique was adopted to analyze the vibration source contribution of plate structures. The theory of the ICA technique is introduced and the procedure of the vibration source contribution analysis based on the ICA technique is proposed. To investigate the applicability of the proposed method to plate structures, numerical examples are presented for a rectar gular plate under harmonic force excitations. The results show that the proposed method could become an effective tool for the vibration source contribution analysis of a plate structure.
골재채취해역의 복원을 위한 굴패각 투하공법별 확산에 관한 연구
이국현(Kookhyun Lee),윤진형(Jinhyeong Yun),이황기(Hwangki Lee) 전남대학교 수산과학연구소 2022 수산과학연구소논문집 Vol.31 No.1
The total amount of oyster shells produced annually in South Korea is estimated to be about 280,000 tons. Of them, 180,000 tons are being recycled as materials for oyster or Porphyra seed collection, shell fertilizers, and treated by contracted waste management companies. The rest, 100,000 tons, are illegally disposed of at farm sites or near the business facilities, causing severe environmental problems such as pollution of coastal fishing grounds, destruction of the landscape, and disturbance in the management of public waters. Multiple dumping methods of oyster shells comprise restoration measures that utilize unprocessed oyster shells to restore the sand mining zone within the South Sea of the Korean peninsula’s exclusive economic zone (EEZ). On that note, this study aims to conduct primary research to calculate the range of diffusion effects of each dumping method of oyster shells. Accordingly, the researchers collected unprocessed oyster shells from five oyster shucking fields near the South coast three in Tongyeong, one in Geoje, and one in Goseong, and measured the settling velocity by the respective size of the oyster shells in a hydraulic experiment. In addition, the diffusion distance of each dumping method was calculated by using a Computational Fluid Dynamics (CFD).