• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.498-502
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• 2011

The divergent synthesis of novel phosphorus-containing dendrimer with 4,4'-sulphonyldiphenol at the core has been accomplished involving simple condensation reactions using $P(O)Cl_3$, $P(S)Cl_3$, 3-amino-phenol, 3-hydroxy-benzaldehyde, and 2-butyn 1, 4-diol. The final compound was a Schiff's base macromolecule possessing 4 imine bonds, 8 acetylenic bonds and 8 OH groups at the periphery. The structures of intermediate compounds were confirmed by IR, NMR ($^1H$, $^{13}C$ and $^{31}P$), LC-Mass and C, H, N analysis. The structure of the final dendrimer (5) was confirmed by IR, NMR ($^1H$, $^{13}C$ and $^{31}P$), MALDI-TOF-MS, and C, H, N analysis. The surface morphological characteristics of the final dendrimer were understood by Scanning Electronic Microscopic study (SEM). The thermal stability of the final dendrimer was studied by TGA/DTA analysis.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1557-1563
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• 1991

Vendors and consultants struggle to draw attention to their proven experience in discrete CIM in order to convince process manufacturers to adopt CIM technology. The analogy works very well at the periphery where an invoice is an invoice, but disintegrates at the core where modeling of the manufacturing "process" is required. Until recently, it has not been possible to completely and rigorously model entire process plants in real-time, and this missing core element has been called the "CIM GAP" With the recent introduction of the concurrent resolution $^{sm}$ kernel, the CIM GAP now is being closed in the process industries.ntroduction of the concurrent resolution $^{sm}$ kernel, the CIM GAP now is being closed in the process industries.

• Restorative Dentistry and Endodontics
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• v.9 no.1
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• pp.115-119
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• 1983

The purpose of this study was to compare the solubility of enamel and dentin to an etchant after fluoride application. Specimens were collected from extracted anterior and bicuspid and each tooth was cut into several pieces. These specimen were allocated in 7 group; 1%, 2%, 3% NaF, 1%, 8%, 20% $SnF_2$, and control group. Five specimens in each group was exposed to pre-determined fluoride solution for 3 minutes, and washed with running water. These specimens were etched by Hipol (commercial label) etchant for 30 seconds. Following are the findings obtained through S.E.M. 1. All specimens with acid etching revealed preferential removal of prism periphery leaving prism core. 2. Specimens treated with 1%, 2% NaF solution showed that the shape of prism tip was thin and sharp like a needle. The case of 3% NaF showed rather round shape at prism end. 3.1% of $SnF_2$ case showed similar findings with the control group but 8% and 20% $SnF_2$ case revealed needle shape at the prism and was less clear than NaF case. Preferential removal of prism periphery was partialy observed and un decalcified area is fused to prism forming reidge. 4. Dentine treated by fluoride compound in low concentration showed the orifice of dentinal tubule was clearly enlarged whereas in high concentration the orifice was not widened.

• Journal of the Korean Regional Science Association
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• v.6 no.2
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• pp.123-147
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• 1990

This paper examines the changing geography of producer service industries in the 1980s. The foci of this study are to analyze the regional distribution of each producer services, and to reveal the spatial linkage of producer services. Further this paper asserts the potential role of producer services for reducing the potential endogenous development in the periphery. During the 1981-86 period, producer service industries grew more rapidly than other service sectors and manufacturing sector. The main reason of the raid growth of producer services is attributable to an increase in demand for intermediate services from manufacturing firms. In order to compete an increasingly complex business environment, firms have expanded the amount of effort devoted to activities such as planning, coordination and control, and consequently have increased their use of producer services. The most distinctive feature of the location of producer services is spatial concentration into Seoul and surrounding region. Especially the degree of the concentration o business services into the Capital Region has been accelerating during the 1990s. The pattern of employment growth and regional distribution of producer services show a clear core / periphery disparity. Much of the regional inequality in producer services is largely due to variation in demand associated with the pattern of corporation headquarters with the pattern of corporation headquarters and branch plants location with large manufacturing firms. The analysis of spatial division of labor reflects that producer services are related to the location of headquarters in manufacturing industry. Headquarters in manufacturing firms and business service firms tend to cluster each other. Most of the headquarters spatially separated from branch offices are clustered heavily in Seoul. Especially headquarters of business services and insurance services are overwhelmingly concentrated into Seoul. The firms whose headquarters are located in Seoul have a linkage pattern on a nationwide scale. It is viewed have little potential for generating local multiplier effects and regional development. In the light of the result of this study, producer services are not likely to disperse soon to peripheral regions. Consequently the absence of policies directed at enhancing producer sevice in the periphery, concentration tendency would continue to reinforce the core's dominance at the expense of peripheral regions. From a regional perspective, the quality of a region's producer service sector is a key determinant of economic growth, since manu industrial location decisions are influenced by the differential availability of producer services among regions. Poor performance of producer services in peripheral regions seemed to be linked to the region's manufacturing base. Low-wage, standardized branch plants are not likely to induce the growth in knowledge intensive services associated with high-technology corporate headquarters. Producer services may help to create and attract new business including manufacturing firms, and also to enhance the productivity and competitiveness of local firms. Therefore the provision of service producing activities would be lead not only to generate and retain endogenous development but also to attract external firms, especially small and medium sized firms which have a lower propensity of internalized services. Hence, it may be more efficient to create and expanse new locally owned producer services rather than to attract branch plants of mult-locational firms in order to make indigenous economic development.

• Information Systems Review
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• v.25 no.2
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• pp.77-101
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• 2023

Due to COVID-19, paid virtual live-stream concerts have emerged as an alternative format and a new revenue model for in-person live concerts. Despite the increasing scholarly and practical interest in how participants experience paid virtual live-stream concerts, few studies examined participants' consumption and participation experiences. Thus, this study aims to provide insights into consumers' virtual live-stream concert experience by employing social representations theory (SRT). We explore the features of paid virtual live-stream concerts based on the C-P-N-D (Content-Platform-Network-Device) framework and the consumers' cognitive and affective perception. To this end, an SRT-based core-periphery analysis was conducted based on 239 responses to the open-ended survey questions. The results show that network-and device-level features of virtual live concerts and participants' overall perception are presented as core elements of paid virtual live-stream concerts, whereas content- and platform-level features are peripheral elements. This finding provides an in-depth understanding of the emergence of paid virtual live-stream concerts as an alternative concert format, thereby providing an invaluable understanding of a virtual live concert experience and theoretical and practical insights.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.761-766
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• 2008

Photoresponsive arylether dendrimers Bis-azo-Gn(3,5) 1a-1c and Bis-azo-Gn(3,4,5) 2a-2c (n = 1-3) with an azobenzene unit at the core and several vinyl groups (3,5-bis(but-3-enyloxy)phenyl groups or 3,4,5-tris(but-3- enyloxy)phenyl groups) at the periphery have been prepared. Their structures and reversible trans-cis isomerization behaviors have been investigated by $^1H$-NMR, $^{13}C$-NMR, MALDI-TOF-Mass, and UV-vis spectra. All six azobenzene-cored dendrimers carried out very fast trans $\rightarrow$ cis photoisomerization on irradiation of 350 nm light and reached to the photostationary state within 180 s. During the dark incubation, slow thermal back reversion from cis to trans form is observed for all six dendrimers and is completed within 3 days for 1a-1c and 1 day for 2a-2c. Isomerization efficiency decreases with increasing generation. However, the initial reaction rates of both trans $\rightarrow$ cis photochemical isomerization and cis $\rightarrow$ trans thermal isomerization increases significantly with increasing generation for dendrimers for 1a-1c but only slightly for 2a-2c.

• Journal of the Korean Geographical Society
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• v.30 no.2
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• pp.169-187
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• 1995

Contemporary US metropolitan areas have undergone divergent economic transformation, and as a result labor markets have become the focus of concern in their role as determinants of earnings attainment. Explanations of individual earnings attainmnent as a lobor market outcome have been established in two diafferent stances one who emphasizes personal or group attributes in the human capital perspective and the other who emphasizes economic structure in the labor market segmentation perspective. While remaining at the conceptual level and yet relatively unexplored, the importance of place in labormarket operation is a significant advancement as it appears in labor market areas and local labor markets considering that labor market areas represent the intersection of labor market structure and individual labor market experiences at specific geographic places. The substantive inquiry of this study was to explore labor market characteristics and their differentiation across large metropolitan areas, and assess their effects on the individual earnings attainment. Integating individual attributes and labor market characteristics as major factors of labor market operation, this study intended to contextualize individual earnings attainment with geographic labor market areas. Using 1990 US population census 5% "Public-Use Microdata Samples, " the largest 65 metropolitan areas were first selected and employed male workers who are aged between 25 and 50 for whites, blacks, asians, and hispanics. As an initial step earnings differentials between racial/ethnic groups and selected 65 metropolitan areas were examined using analysis of variance, and then earnings differentials were attributed to the individual attributes such as education, age, and immigration status, and four dimensions of metropolitan labor market differentiation devised by principal component analysis of industrial and occupational segments: Public versus Blue Collar Core(CS1), Finance-Core Utility versus Blue Collar Local Monopoly (CS2), Oligopoly versus Blue Collar Periphery(CS3), and Self Employed-White Collar Periphery versus Low-Skill Core(CS4). As a final analysis, individual earnings were related to each individual attribute and its interaction with metropolitan labor market characteristics to examine how the differentiated metropolitan labor market characteristics alter the role of individual attributes on earnings attainment. The findings indicated that individual attributes, education in particular exert significant effects on earnings attainment, but their effects were significantly altered by metropolitan labor market characterristics. Particularly important dimensions were: Oligopoly differentiated from Blue Colla Periphery metropolitan areas enhancing earnings returns to individual attributes for all groups but minority groups (black, asians, hispanics) rely more on this, and Finance-Core Utility differentiated from Blue Collar Local Monopoly metropolitan areas provide higher earnings returns to whites exclusively. These findings suggest that individuals with identical individual attributes involving racial/ethnic categories would have different earnings atteinments depending on the metropolitan labor market characteristics where they reside. Referring back to the major traditions of the human capital and the labor market segmentation in labor market research, the interaction between individual attributes and metropolitan labor market haracteristics on earnings attainment highlights the complimentary nature of the two on earnings determination in particular geographic places, Hence, labor market characteristics differentiatcd across metropolitan areas are an integral part of labor market operation which should be considered for the explanation of individual earnings attainment and racial/ethnic group earnings differentials. Gcographic places are the important contexts for labor market segmentation and individual labor market experiences. In conclusion, this study brings geographic labor markets to the forefront in the examination of individuals' earnings attainments. The empirical vaidation of the role of metropolitan labor market charecteristics on earnings attainment, while exploratory contributes towards a broader perspective of geographic labor market research that recognizes that individuals' labor market experiences are intertwined with geographic contexts of labor market operatin. operatin.

• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.55-63
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• 2016

Calculation of the core neutronic parameters is one of the key components in all nuclear reactors. In this research, the energy spectrum and spatial distribution of the neutron flux in a uranium target have been calculated. In addition, sensitivity of the core neutronic parameters in accelerator-driven subcritical advanced liquid metal reactors, such as electron beam energy ($E_e$) and source multiplication coefficient ($k_s$), has been investigated. A Monte Carlo code (MCNPX_2.6) has been used to calculate neutronic parameters such as effective multiplication coefficient ($k_{eff}$), net neutron multiplication (M), neutron yield ($Y_{n/e}$), energy constant gain ($G_0$), energy gain (G), importance of neutron source (${\varphi}^*$), axial and radial distributions of neutron flux, and power peaking factor ($P_{max}/P_{ave}$) in two axial and radial directions of the reactor core for four fuel loading patterns. According to the results, safety margin and accelerator current ($I_e$) have been decreased in the highest case of $k_s$, but G and ${\varphi}^*$ have increased by 88.9% and 21.6%, respectively. In addition, for LP1 loading pattern, with increasing $E_e$ from 100 MeV up to 1 GeV, $Y_{n/e}$ and G improved by 91.09% and 10.21%, and $I_e$ and $P_{acc}$ decreased by 91.05% and 10.57%, respectively. The results indicate that placement of the Np-Pu assemblies on the periphery allows for a consistent $k_{eff}$ because the Np-Pu assemblies experience less burn-up.

• Korean Journal of Veterinary Research
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• v.33 no.4
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• pp.573-577
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• 1993

The pancreatic endocrine cells, glucagon and somatostation, of the Korean tree squirrel. Sciurus vulgais corea, were investigation by means of light and electron microscopic immunohistochemistry using the PAP and protein A-gold techniques. Glucagon-immunoreactive cells were distributed the periphery and occasinonaly central region of the pancreatic islets. Also, isolated cell was found between the pancreatic ancinar cells. The glucagon cells contraine granules with a diameter of 240~320nm and the electron dense core usually surrounded by a halo of less dense granular material. The core of granule was labelled strongly with gold particles. Somatostatin-immunoreactive cells were weakly stained in scattered along the peripheral pancreatic islets and were distributed as singly or small groups with in the pancreatic acinar cells. The somatostatin cells were spherical with a diameter of 250~275nm, moderately electron opaque (Gold particles were mostly demonstrated on the entire granule.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.977-983
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• 2007

Recently, the number of systems which utilize wireless power transmission to a receiving module in a short distance is increasing. For efficient use of receiving space, coils are wound around the ferrite core to produce electromotive force(emf) in suppling power by wireless transmission. This paper analyzed the magnetic flux density distribution in the ferrite core in magnetic field environment which is uniformly oriented along to a single axis at 125kHz. For numerical analysis, Ansoft Maxwell which is applying the FEM(Finite Element Method) method was used. We studied the variations of the gathered magnetic fluxes to the changes of the relative permeabilities of the ferrite cores. Also we calculated the magnetic flux variation by shaving the ferrite core off for the groove of coil winding. Results showed that using a small ferrite core in magnetic field at 100kHz band can increase the amount of magnetic flux $3{\sim}4 times$ than without the core. The magnetic flux decreased 23% by shaving the core 0.5 mm on the periphery of 4.75 mm radius core with the relative permeability 800.