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Synthesis of Cobalt Containing Block Copolymers Via Ring Opening Metathesis Polymerizastion (ROMP)

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Journal of Rare Earths 2004年第z2期22卷 145-152页

作者： Bongjin moon Minhyuk kang Departmen of Chemistry Sogang UniversityShinsoo-Dong 1-1Mapo-GuSeoul121-742Korea Departmen of ChemistrySogang UniversityShinsoo-Dong 1-1Mapo-GuSeoul121-742Korea

In order to realize a metal containing nano-structure, a block-copolymer containing alkynyl groups in one block was designed and synthesized by living ring opening metathesis polymerization (ROMP) technique. The newly developed bis-3-bromopyridine complex of Grubbs catalyst was employed in the series of polymerization and it yielded the desired polymers with great molecular weight control and narrow polydispersities. The characteristics of the block copolymers were investigated by gel permeation chromatography, H- and 13H- NMR spectroscopy. Complexation of the alkynyl group containing block copolymers by treatment with dicobalt octacarbonyl occurred smoothly in 5 min at room temperature. GPC analysis before and after cobalt complexation indicated a significant increase of the hydrodynamic volume. AFM images of the films before and after the complexation also showed a noticeable change in its morphology where grain sizes become smaller and more regular upon complexation.

关键词： ring opening metathesis polymerization (ROMP) metal containing block copolymer polynorbornene derivative

Suggestion of advanced regression model on friction angle of fault gouge in South Korea

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第6期13卷 1368-1379页

作者： seong-Woo moon Hyun-seok Yun Yong-seok seo Department of Earth and Environmental Sciences Chungbuk National University1 Chungdae-roCheongju-siChungcheongbuk-do28644South Korea

Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than those of soils or rocks due to its high heterogeneity and low ***,to improve the accuracy of analysis results,we conducted simple regression analysis and structural equation model analysis and selected major influential factors of friction characteristics among many factors,and then we deduced advanced regression model with the highest coefficient of determination(R^(2)) via multiple regression *** most coefficients of determination in simple regression analysis are below0.3-0.4,coefficient of determination in multiple regression analysis is remarkably large as 0.657.

关键词： Fault gouge Friction angle Simple regression analysis Structural equation model analysis Multiple regression analysis

Grain Size Control of Semisolid A356 Alloy Manufactured by Electromagnetic Stirring

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Journal of Materials Science & Technology 2005年第2期21卷 219-225页

作者： P.K.seo C.G.kang National Research Lab of Thixo-Rheo FormingSchool of Mechanical Engineering Pusan National University Pusan 609-735 KoreaNational Research Lab of Thixo-Rheo FormingSchool of Mechanical Engineering Pusan National University Pusan 609-735 Korea

To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carried out. It was found that in the early period of solidification, the dendrite breakages led to a fine primary phase. When dendrites grew coarsely, the effect of ripening on grain size overwhelmed that of dendrite breakage. It was also found that the high cooling rate favored large nucleation rate, and led to a fine primary phase. But high cooling rate also made the growth rate of the dendrite arm, which prevented the dendrite arm from being sheared off. Therefore there were a suitable stirring time and suitable cooling rate to obtain the best rheo die-casting structure. Qualified semisolid A356 aluminum alloy was successfully manufactured with short time EMS.

关键词： Semisolid metal process Electromagnetic stirring Rheo die-casting Grain size control

Diel vertical migration of the copepod Calanus sinicus before and during formation of the Yellow Sea Cold Bottom Water in the Yellow Sea

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Acta Oceanologica Sinica 2013年第9期32卷 99-106页

作者： kang Jung-Hoon seo MinHo KWON Oh Youn KIM Woong-seo South Sea Environment Research Division Korea Institute of Ocean Science&Technology (KIOST) Deep-sea and Seabed Resources Research Division

To understand the effects of the Yellow Sea Cold Bottom Water （YSCBW） on the diel vertical migration （D- VM） of the copepod Calanus sinicus, we surveyed vertical distribution of C. sinicus at a fixed station in the Yellow Sea before （spring） and during （summer） formation of the YSCBW. Cold water （〈10℃） was observed in the bottom layer when the water column was thermally stratified in summer, but the water column was thermally well-mixed in spring 2010. Samples were collected from five different layers at 3-h intervals using an opening-closing net. Adult females （1-155 ind./m3） showed a clear normal DVM pattern throughout the entire water column in spring, whereas adult males did not migrate. DVM of copepodite V （CV） individuals was not clear, but the maximum abundance of CI-CIV occurred consistently in the upper 10-20 m layer, where there was a high concentration of chlorophyll-a （Chl-a）（0.49-1.19μg/L）. In summer, weak DVM was limited to cold waters beneath the thermocline for adult females （〈30 ind./m3）, but not for adult males. The maximum abundance of CI-CIV also occurred consistently in the subsurface layer （20-40 m） together with high concentrations of Chl-a （0.81-2.36 μg/L）. CV individuals （1-272 ind./m3） moved slightly upward noc- turnally to the near-surface layer （10-20 m）, where the average temperature was 25.74℃, but they were not found in the surface layer （0-10 m; 28.31℃）. These results indicate that the existence of the YSBCW affected food availability at depth and the vertical temperature distribution, leading to variation in the amplitude and shape of stage-specific vertical distributions （CI to adults） in C. sinicus before and during the formation of cold waters in the Yellow Sea during the study period.

关键词： Yellow Sea Cold Bottom Water (YSCBW) copepod Calanus sinicus developmental stages,diel vertical migration (DVM)

Application of signal processing techniques to the detection of tip vortex cavitation noise in marine propeller

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Journal of Hydrodynamics 2013年第3期25卷 440-449页

作者： LEE Jeung-Hoon HAN Jae-moon PARK Hyung-Gil seo Jong-Soo Samsung Ship Model Basin (SSMB) Marine Research Institute Samsung Heavy Industries Science TownDaejeon 305-380 Korea

The tip vortex cavitation and its relevant noise has been the subject of extensive researches up to now. In most cases of experimental approaches, the accurate and objective decision of cavitation inception is primary, which is the main topic of this paper. Although the conventional power spectrum is normally adopted as a signal processing tool for the analysis of cavitation noise, a faithful exploration cannot be made especially for the cavitation inception. Alternatively, the periodic occurrence of bursting noise induced from tip vortex cavitation gives a diagnostic proof that the repeating frequency of the bursting contents can be exploited as an indication of the inception. This study, hence, employed the Short-Time Fourier Transform （STFT） analysis and the Detection of Envelope Modulation On Noise （DEMON） specmma analysis, both which are appropriate for finding such a repeating frequency. Through the acoustical measurement in a water tunnel, the two signal processing techniques show a satisfactory result in detecting the inception of tip vortex cavitation.

关键词： tip vortex cavitation inception Short-Time Fourier Transform (STFT) Detection of Envelope Modulation On Noise(DEMON)

Improvements of model-test method for cavitation-induced pressure fluctuation in marine propeller

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Journal of Hydrodynamics 2013年第4期25卷 599-605页

作者： LEE Jeung-Hoon HAN Jae-moon PARK Hyung-Gil seo Jong-Soo Samsung Ship Model Basin (SSMB) Marine Research Institute Samsung Heavy Industries Science Town

Although the prediction of propeller cavitation-induced pressure fluctuation strongly depends on the model-scalemeasure- ment in a cavitation tunnel, there is still a lack of correlation with full-scale data. This paper deals with the enhancement of such a correlation deficiency by improving the conventional model-test technique, two majors of which are in the following. One is to take into account the boundary layer effect of wooden fairing plate at the ceiling of water cavitation tunnel. The other is to avoid the reso- nance frequency range of model-ship via adjusting the revolution speed of model propeller. Through a case study, for which both model and full-scale test data are available, the improved method in this study shows its validness, and furthermore a close correla- tion with full scale measurement.

关键词： cavitation boundary layer resonance

Degradable and Tunable Keratin-fibrinogen Hydrogel as Controlled Release System for Skin Tissue Regeneration

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Journal of Bionic Engineering 2023年第3期20卷 1049-1059页

作者： Sung Jun Min Jae seo Lee Haram Nah Ho-Jin moon Sang Jin Lee Hyeon Jeong kang Yu-Shik Hwang Il Keun Kwon Dong Nyoung Heo Department of Dentistry Graduate SchoolKyung Hee University26 Kyungheedae-RoDongdaemun-GuSeoul02447Republic of Korea Biofriends Inc 26 Kyungheedae-RoDongdaemun-GuSeoul02447Republic of Korea Department of Dental Materials School of DentistryKyung Hee University26 Kyungheedae-RoDongdaemun-GuSeoul02447Republic of Korea Department of Maxillofacial Biomedical Engineering and Institute of Oral Biology School of DentistryKyung Hee UniversitySeoul02447Korea Kyung Hee University Medical Science Research Institute Kyung Hee University23 Kyungheedae-RoDongdaemun-GuSeoul02447Republic of Korea

Biodegradable hydrogels are promising biomaterials for use in controlled-release systems for skin tissue regeneration. Controlled delivery systems constitute an important aspect of tissue engineering because they can modulate various physiological responses, including early immune response, tissue remodeling, and cell proliferation and maturation in the wound-healing process. Hydrogels composed of various biomaterials have been developed to overcome the limitations of conventional drug- or protein-delivery systems, such as limited targeting ability, low stability, and the induction of drug resistance. Hydrogels based on keratin, a natural polymer extracted from human hair, can provide adequate cell support and control homeostasis. Consequently, they can be applied for skin tissue engineering. In this study, we prepared degradable, tunable, and biocompatible hydrogels for controllable protein delivery. We synthesized keratin-fibrinogen (KER-FBG) by the chemical coupling reaction and prepared hydrogels through polymerization with thrombin. The structures and morphologies of the KER-FBG hydrogels were confirmed. Furthermore, the mechanical properties, swelling ratio, degradation, release behavior, and biocompatibility were investigated. The KER-FBG hydrogels presented promising biological performance, indicating that the material is suitable as a controlled protein delivery carrier.

关键词： Keratin Fibrinogen Hydrogel Drug delivery Degradable

Fluorine doping for improved thermoelectric properties of spark plasma sintered bismuth telluride

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Journal of Materials Science & Technology 2021年第31期90卷 225-235页

作者： Jinseo Kim Le Thai Duy Hyunwoo kang Byungmin Ahn Hyungtak seo Department of Energy Systems Research Ajou UniversitySuwon 16499South Korea Department of Materials Science and Engineering Ajou UniversitySuwon 16499South Korea

Bismuth-telluride(Bi_(2)Te_(3))is considered to have the best thermoelectric properties at room temperature(ca.300 K).Thus,synthesis and improvement of Bi_(2)Te_(3)and its derivatives quickly and cost-effectively at favorite temperatures are of ***,doping fluorine(F)into electronic materials(e.g.,FTO)has gained attention;however,it is not applied to Bi_(2)Te_(3)till ***,our synthesis of F-doped Bi_(2)Te_(3)for thermoelectric application is introduced using spark plasma sintering(SPS)for Bi_(2)Te_(3)preparation and reactive ion etching(RIE,with SF_6 gas)for *** exposure time of SF_6 plasma is adjusted to evaluate F-doping effect on the thermoelectric properties of the *** characterizations,the increased electrical conductivity and the improved Seebeck coefficient of F-doped Bi_(2)Te_(3)are *** spectroscopic studies and DFT calculations,the main mechanism behind that improvement is *** also emphasizes the essential role of the F-doping(optimum treatment time of 40 s)in increasing the carrier concentrations as well as electrical *** increasing measurement temperature(300-510 K),F-doping raises the figure of merit of electron rich Bi_(2)Te_(3)from 1.0 to 1.11(peaked at 390 K).

关键词： Bismuth-telluride Fluorine Doping Thermoelectric Spark plasma sintering

Evaluation of vibration and sound quality according to battery voltage change while moving a power seat in an automobile forward or backward

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Journal of Central South University 2014年第10期21卷 3844-3849页

作者： kang-seok seo Doo-seuk Choi Key-sun Kim Department of Mechanical Engineering Graduate School Kongju National University Division of Automotive and Mechanical Engineering Kongju National University

The changes in vibration, sound, and sound quality with changes in the driving voltage of a power seat motor from 12.5 to 14.5 V were measured and analyzed, which was used in real vehicles. BSR(buzz, squeak, rattle), which occurs for the power seat mechanism during sliding operation, was also evaluated. In addition, the results were expressed in terms of sound quality metrics, which measure the RPM change and sound level versus voltage to analyze their statistical correlation. Furthermore, vibration measurement and analysis were conducted simultaneously to determine the noisiest conditions and the source of the noise. The changes in RPM and voltage of a motor, in addition to vibration and noise, were measured at the same time to determine how noise, RPM, and voltage are interrelated.

关键词： seat vibration seat noise sound quality voltage buzz squeak and rattle(BSR)