• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.369-376
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• 2000

Change of magnetic properties in CoCrPt/Ti perpendicular media with varying CoCrPt films thickness has been studied. As CoCrPt films thickness increase, the Ms(magnetization saturation) drastically increases at thinner thickness and gradually increases with further increase in thickness from 25nm. This Ms behaviour is associated with primarily the formation of "amorphous-like" reacted layer by intermixing of CoCrPt and Ti at CoCrPt/Ti interface and secondarily change of Cr segregation mode with varying the CoCrPt films thickness. Magnetic domain structure distinctively changes with increasing CoCrPt magnetic layer(ML) thickness. Also the strength of exchange coupling measured from the slope in demagnetizing region in M-H loop changes with ML thickness. Details of the above magnetic properties will be discussed. The expansion of lattice parameters a and c at thinner thickness suggests that Cr segregation mode may be connected with the residual stress of the films. Finally, negative nucleation field(Hn) behaviour with the exchange slope will be reported.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2001.06a
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• pp.149-153
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• 2001

To investigate the mode of bactericidal action for antimicrobial peptide, pediocin, synthetic and mutant pediocins were prepared by direct chemical synthesis. Native pediocin was purified from Pedio-coccus acidilactici M and its conformational structure and bactericidal functions were analyzed and compared to synthetic pediocin. Schematic mode of pediocin actions, how pediocin binds on the target cell membrane, penetrates and makes tunnel are proposed. For these purposes, primary and secondary structures of pediocin was analyzed and disulfide bond assignment was also done. The pediocin purified from P. acidilactici M had high effective bactericidal ability against gram positive bacteria, especially Listeria monocytogenes and was very stable at extreme pHs and even at high temperatures such as autoclaving temperature (121$^{\circ}C$). Pediocin was consisted of 44 amino acids with four cysteines. Novel synthetic peptides were achieved by solid phase peptide synthesis(SPPS) method. To explain the function of cysteine in C-terminal region, mutant pediocin, Ped[C24A＋C44A], was synthesized and their structural and biological functions were analyzed. Second mutant pediocin, Ped[KllE], was prepared to explain the function of lysine at 11 of N-terminal part of pediocin, especially loop of $\beta$-sheet, and to predict the initial binding site of pediocin. The native and synthetic pediocins was showed random coil conformation by spectropolarimetry in moderate conditions. This conformation was observed in extreme conditions such as high temperature and low and high pHs, also. Circular dichroism(CD) data also showed the existence of $\beta$-turn structure in N-terminal part both native and synthetic pediocins. A structural model for pediocin predicts that 18 amino acids in the N-terminal part of the peptide assume a three-strand $\beta$-sheet conformation. This random coil in C-terminal part of pediocin was converted to folding structure, helix structure, in nonpolar solvents such as alcohol and TFE. The disulfide bond between $^{9}$ Cys and $^{14}$ Cys was concrete and inevitable, however, evidences of disulfide bond between $^{24}$ Cys and $^{44}$ Cys was not. Data of Ped[C24A＋C44A], pediocin mutant showed that $^{44}$ Cys was required during killing the target cells but not inevitable, since Ped[C24A＋C44A] still have bactericidal activity but much less than native pediocin. Another pediocin mutant, Ped[KllE], had still bactericidal activity, was controversial to propose that positive charge like as $^{11}$ Lys in loop or hinge in bacteriocin bound or helped to binding to microorganism with electrostatic interaction between cell membrane especially teichoic acid and positive amino acid nonspecifically. The conformation of pediocin among native, synthetic and mutant pediocins did not show big difference. The conformations between oxidized and reduced pediocin were almost similar regardless of native or synthetic.

• Journal of Veterinary Clinics
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• v.40 no.3
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• pp.215-220
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• 2023

A 3-month-old Korean native cattle (Hanwoo) calf with difficulty taking normal posture and an inability to rise was referred for a definite diagnosis and active treatment, including surgery. The calf had a history of an accident in which both hind limbs were trapped in a barn structure. After admission, a "rabbit leg" posture was observed, a typical sign of gastrocnemius muscle rupture, and both digits were knuckled downward like they were trying to grip the ground. This was considered to be a result of the superficial digital flexor not rupturing but only the gastrocnemius muscle rupturing. Physical examination revealed laceration of the metatarsus and firmness behind both stifle joints which were presumed to be the sites of gastrocnemius muscle rupture. Skeletal abnormalities, including fractures, were ruled out by radiography. Based on these findings, the patient was diagnosed with bilateral gastrocnemius muscle rupture, and surgery was performed to reconnect the head of the ruptured muscle. Because the rupture occurred perpendicular to the muscle direction, the locking loop technique, a method of suturing severed tendons, was used to reduce the tension. After surgery, the cast was used to prevent further injuries and promote voluntary rehabilitation. Follow-up was completed, with the calf showing normal posture and gait 112 days after surgery. This is the first case report in the Republic of Korea describing the successful diagnosis and treatment of bilateral gastrocnemius muscle rupture in a calf.

• Journal of Fashion Business
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• v.23 no.1
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• pp.37-48
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• 2019

WKSF (Warp-knitted spacer fabrics) knitted using a double Raschel machine is the three-dimensional knit that has vertically connected separate layers in loop structures. Because of its unique structure, the fabric is light, compressible and breathable. Owing to the high production speed, the use of the fabric is increasing in various areas. The purpose of this study is to establish the design process in the utilization of WKSF program and analyze the difference between WKSF and Neoprene as garment materials.. The study on the design related to WKSF has rarely been carried out because of the complexity of WKSF structure and the difficulties encountered in analyzing the structure and thread. Therefore, checking beforehand the simulation results similar to a final knit using the CAD program for WKSF can only enhance the efficiency of the design for the light knits. The conclusion drawn after designing the light knits using the CAD program and analyzing the pros and cons of WKSF through the various property evaluation techniques is as follows. The tension characteristic analysis results indicated that Neoprene specimen has the elastic transformation and resilience, thus behaving like an elastic product such as rubber. By contrast, in the event that clothing and fashion accessories are designed with WKSF, these products are kept in a boxy style fit so that the fabric can be applied flexibly to a curvy body line. In addition, WKSF is good in forming noticeably around a curvy body, because its resistance shear deformation is lower than that of Neoprene.

• Journal of Industrial Convergence
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• v.22 no.5
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• pp.39-48
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• 2024

Due to COVID-19, much research has been conducted on learning loss and educational gaps due to the postponement of the start of school and prolonged online distance learning, and most of the research has focused on the phenomenon of educational gaps. If a pandemic situation like this occurs in the future, fundamental policies are needed to resolve the educational gap. A fundamental solution requires not only an understanding of the educational gap phenomenon, but also the structure behind the phenomenon. Therefore, from a structuralist perspective, this study sought to model the educational gap caused by COVID-19 as a prototype of systems thinking and identify its structure. In addition, we looked at the unintended consequences resulting from policies aimed at resolving existing educational gaps. In order to respond to similar disaster situations in the future, policies for resolving the digital gap, support for basic academic skills, quality improvement for distance learning, and self-directed learning were discussed based on the structure of this study.

• Journal of the Korean Society of Costume
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• v.54 no.1
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• pp.23-36
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• 2004

The knitting, which has developed from the onset of human civilization, has a close relation to dwelling as well as to clothing itself. Its progress has taken shape in a variety of forms according to nature-friendly tools and its knit texture in the past is different from that of modern times. With this basic idea, the work aims at the further study of various knitting structure which triggered the origin of modern techniques, the establishment of those methods, and the finding of what means was utilized earlier based on these. By doing that, this study will provide the foundation in the Korean historical timeframe in knitting field and give definition to knit wear in a historical sense. As to definition, the outcome in the research boils down to two categories. broad meaning and narrow meaning. The former can be the hook-formed textile, referring to making, twisting, or binding the knots. On the other hands, the latter, that is, narrow type, can be the loop-linked fabric which can be defined as modern knitting. The knitting dates back to the ancient way of binding structure, combining structure in other words, and braiding structure and this kept dividing into subgroups like Netting. Nalbinding, Sprang and Crochet as the usage of hands and tools by mankind has got improved. And it changed into knitting and crochet which means a bamboo needle-hook knitting (larger needle type) and a crochet-hook knitting (smaller needle type), respectively through middle ages and modern times and settled down to the production of fabric. In this work, Netting, Nalbinding, Sprang and Crochet are classified as ancient category in which these originate the modern knitting method. Though the modern type of knitting is not found in the Joseon Dynasty, some various methods from the ancient twisting skill and binding skill where the materials with easy access to acquisition in the nature such as rattan, straw, horsehair, hemp, rush, cotton, silk and the like to Netting, Nalbinding and Sprang except Crochet were handed down and used in costume for diverse application. This work can provide the basic frame in terms of Korean history of knitting which has been excluded in the relevant researches until now. When applying the study, it would trigger the initiation of more versatile design with which the previous unique techniques along with modern techniques can be adopted in the clothing market as knit designs gain in public favor more and more.

• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.255-270
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• 2006

In this paper, a design method of nonlinear autopilot for ship-to-ship missiles is proposed. Ship-to-ship missiles have strongly coupled dynamics through roll, yaw, and pitch channel in comparison with general STT type missiles. Thus it becomes difficult to employ previous control design method directly since we should find three different solutions for each control fin deflection and should verify the stability for more complicated dynamics. In this study, we first propose a control loop structure for roll, yaw, and pitch autopilot which can determine the required angles of all three control fins. For yaw and pitch autopilot design, missile model is reduced to a minimum phase model by applying a singular perturbation like technique to the yaw and pitch dynamics. Based on this model, a multi-input multi-output (MIMO) nonlinear autopilot is designed. And the stability is analyzed considering roll influences on dynamic couplings of yaw and pitch channel as well as the aerodynamic couplings. Some additional issues on the autopilot implementation for these coupled missile dynamics are discussed. Lastly, 6-DOF (degree of freedom) numerical simulation results are presented to verify the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.8
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• pp.457-466
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• 2002

The speed and position control of SRM(Switched Reluctance Motor) needs the encoder or resolver to obtain the rotor position information. These position sensors can be affected by the EMI, dusty, and high temperature surroundings. Therefore the speed and position sensorless control has been studied widely In this paper, the binary observer of the SRM which has two feedback compensation loops to control the speed of SRM is proposed. One loop reduces the estimation error like the sliding mode observer, and the other removes the estimation error chattering occurred in the sliding mode observer. This observer is constructed on the basis of variable structure control theory and has the inertial term to exclude the chattering. This method has a good estimation performance in spite of nonlinear modeling of SRM. The advantages of the proposed method are verified experimentally.

• Steel and Composite Structures
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• v.19 no.2
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• pp.309-325
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• 2015

A convenient procedure for seismic retrofit of existing buildings is to use passive control methods, like using friction dampers in steel frames with bracing systems. In this method, reduction of seismic demand and increase of ductility generally improve seismic performance of the structures. Some of its advantages are development of a stable rectangular hysteresis loop and independence on environmental conditions such as temperature and loading rate. In addition to friction dampers, masonry-infill panels improve the seismic resistance of steel structures by increasing lateral strength and stiffness and reducing story drifts. In this study, the effect of masonry-infill panels on seismic performance of a three-span four-story steel frame with Pall friction dampers is investigated. The results show that friction dampers in the steel frame increase the ductility and decrease the drift (to less than 1%). The infill panels fulfill their function during the imposed drift and increase structural strength. It can be concluded that infill panels together with friction dampers, reduced structural dynamic response. These infill panels dissipated input earthquake energy from 4% to 10%, depending on their thickness.

• Composites Research
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• v.22 no.3
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• pp.9-17
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• 2009

Nanoindentation behaviours on the films of softer Ag film/harder Cu substrate structure were studied by the molecular dynamics method. As a result, it was shown that the stiffness and hardness of films were strongly dependent on the thickness of films. The stiffness and hardness increased with the thickness of film within a critical range as an inverse Hall-Petch relation. The stiffness and hardness of Cu substrate with Ag film less than 5 nm were observed to be lower than those of bulk silver. In particular, the flower-like dislocation loop was created on the interface by the interaction between dislocation pile-up and misfit dislocation during the indentation of Ag film/Cu substrate with film thickness less than 4 nm, which seemed to be associated with the drop of load in the indentation load versus displacement curve.