• Polymer(Korea)
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• v.25 no.2
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• pp.199-207
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• 2001

In the present study the cure behavior of diglycidyl ether of bisphenol-A(DGEBA) using an anhydride-based hardener in the presence of N,N-dimethyl benzyl amine (BDMA) or 1-cyanoethyl-2-ethyl-4-methyl imidazole (2E4MZ-CN) as an accelerator has been monitored and interpreted from the viewpoint of photophysical properties by means of fluorescence spectroscopy. To do this, 1,3-bis-(1-pyrene)propane (BPP) was well incorporated in the epoxy resin system by mechanical blending. The BPP probe, which is very sensitive to conformational change of the molecule influenced by the surrounding medium, successfully formed intramolecular excimer fluorescence. It is susceptible to the micro-viscosity or local viscosity and molecular mobility according to the epoxy cure. The cure behavior was explained with monomer fluorescence intensity ($I_{M}$ ), excimer fluorescence intensity ($I_{E}$ ) and $I_{M}$ /$I_{E}$ ratio as a function of cure time, cure temperature and accelerator. The present work agreed with the previous report on the cure behavior of an epoxy-anhydride system studied using DSC or torsion pendulum method. This study also suggests that the use of fluorescence technique may provide information on cure behavior of a thermosetting resin in a low temperature region, which has not been well interpreted by other analytical methods.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.550-556
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• 2005

Tooth impaction is defined as a cessation of the eruption of a tooth at the level of the oral mucosa or alveolar bone by any causes. Any tooth in the dental arch can be impacted, but the teeth frequently involved in a descending order are the mandibular and maxillary third molars, the maxillary canines, the mandibular and maxillary second premolars, and the maxillary central incisors. In these teeth, impaction of maxillary incisor occurs in about 0.1-0.5% and major causes are trauma, supernumerary teeth and periapical inflammation of primary maxillary incisor. Delayed eruption of a maxillary central incisor results in midline shift, the space's being occupied by an adjacent tooth and different levels of alveolar height. Treatment options are observation, surgical intervention, surgical exposure and orthodontic traction, transplantation and extraction. These cases were about the patients with delayed eruption of maxillary central incisor. We surgically exposed impacted tooth and guided it into normal position by the orthodontic traction. At the completion of traction, the maxillary central incisor was positoned fairly within the arch and complications such as root resorption were not observed.

• Polymer(Korea)
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• v.37 no.6
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• pp.669-676
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• 2013

Demineralized bone particle (DBP) is a biomaterial used widely in the field of tissue engineering. In this study, in order to study the effect of DBP/poly(lactic-co-glycolic acid) (PLGA) scaffold on disc regeneration in vivo environment, we prepared the porous DBP/PLGA hybrid scaffold. Disc defect was induced by removing the nucleus pulposus tissue after incision the annulus fibrosus tissue in half and scaffolds were transplanted. After 1, 2 and 3 months later, the extracted discs were confirmed by collagen synthesis and glycosaminoglycan (sGAG). We conducted histology (H&E, Safranin-O, Alcian blue, Type I Collagen, Type II Collagen). From the results, it was confirmed that collagen and sGAG content were high in DBP/PLGA scaffold, and the regeneration of intervertebral disc was possible.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.4
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• pp.269-274
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• 2021

In secret communication, steganography is the sending and receiving of secret messages without being recognized by a third party. In the spatial domain method bitwise information is inserted into the virtual bit plane of the decomposed pixel values of the image. That is, the bitwise secret message is sequentially inserted into the least significant bit(LSB) of the image, which is a cover medium. In terms of application, the LSB is simple, but has a drawback that can be easily detected by a third party. If the upper bit plane is used to increase security, the image quality may deteriorate. In this paper, I present a method for concealing Hangul secret messages in image steganography based on the lo-th bit plane and the decomposition of modified pixel intensity values. After decomposing the Hangeul message to be hidden into choseong, jungseong and jongseong, then a shuffling process is applied to increase confidentiality and robustness. PSNR was used to confirm the efficiency of the proposed method. It was confirmed that the proposed technique has a smaller effect in terms of image quality than the method applying BCD and Fibonacci when inserting a secret message in the upper bit plane. When compared with the reference value, it was confirmed that the PSNR value of the proposed method was appropriate.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.4
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• pp.1-14
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• 2021

This study examined the techniques of creating gardens overseas using native plants from the Korean peninsula, focusing on the case of 'Das Dritte Land', an art garden created in Berlin, Germany. While Korean garden artists are recognized worldwide and are planning to globalize Korean gardens, the purpose of this study is to share information so that Korean gardeners can expand their activities and rediscover the utilization and value of plants native to the Korean peninsula. The work began as part of a project to mark the 30th anniversary of the collapse of the Berlin Wall. To realize the landscape of Korea with the motif of Inwang Jesaekdo, the geographical shape of the Baekdu-Daegan trail was reproduced with black stone, and the naturalization of Korean peninsula species was utilized in the creation of a garden Berlin. It is a surreal bio-top utopia that blooms with the bio-groups of the Korean peninsula. This study examined the process of plant survey analysis, transportation and stabilization, planting planning, composition and monitoring, and targeting the self-growth of the Korean peninsula, which is a symbol of harmony between the South and the North. The planting of Korea's native plants in overseas gardens symbolizes the uniting of the ecosystems on the Korean peninsula. The process of the Korean peninsula's young plants taking root, flowering, and spreading along Germany's previously divided border metaphorically conveys the desire for the unification of the Korean peninsula. In addition, various art programs in the garden space suggest a foundation for cultural dialogue and communication between the two Koreas. Moreover, creating gardens overseas implies that the cooperation of plant research institutes plays an important role in the transfer of plants and the maintenance of life, while the advancement of Korean gardens overseas plays an essential role in the spread of garden culture in our country.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.583-589
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• 2021

This study is a study on the development of virtual reality to prepare for the increase in disasters of households living with companion animals due to the increase of companion animals. The increase in single-person households and DINKs(Double Income, No Kid) along with the low birth rate and aging population is raising the risk of disasters caused by companion animals in particular. Among these disasters, there is an increase in the occurrence of fires primarily due to the raising of companion animals. Electric stove fires caused by pets are the most common fires. In particular, the frequency of electric stove fires caused by cats is the highest. Careful precautions by the owner are necessary to reduce fires caused by pets. Parenting of companion animals causes pet loss syndrome due to emotional exchange. There are injuries to pets in escalators and injuries to owners in elevators due to disasters caused by the owner's negligence. In order to reduce injuries on escalators and elevators, basic etiquette for using escalators and elevators with pets is required as basic etiquette. It is necessary to utilize virtual reality to reduce disasters caused by such companion animals. Virtual reality can be experienced without a physical space in advance training to overcome disasters, so real disaster cases can be experienced immersively. Therefore, learning how to reduce fires caused by companion animals, disasters caused by owner's negligence, and petloss syndrome through virtual reality will greatly contribute to disaster prevention and reduction of social costs.

• Journal of Korean Library and Information Science Society
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• v.55 no.1
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• pp.193-214
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• 2024

This study aimed to propose a method for collecting and applying media platform based materials at the National Library of Korea. Firstly, we analyzed the current status and limitations of data collection based on domestic media platforms, including the National Library of Korea. Secondly, a literature review method was used to investigate the current status and types of digital content based on media platforms. Thirdly, we identified the types of materials based on media platforms that are not currently included in the National Central Library's online material collection guidelines through the examination of cases from major overseas libraries. Fourthly, after reviewing technical and legal elements such as the definition of collection targets and scope for each new media, and collection methods, we established collection criteria. Fifthly, based on the research results, the policies proposed in this study are as follows: 1) there is a need to establish a clear legal basis for the collection of media platform based materials; 2) the development and presentation of collection guidelines for media platform based materials is necessary; 3) the development of collection tools and infrastructure for media platform based materials is required; 4) for the collection of media platform based materials, it is necessary to obtain permission for collection from targeted social media organizations, and to cooperate in linkage with organizations that produce and service extended reality content; 5) for the service activation of media platform based materials, it is necessary to improve accessibility for the usage activation of these materials, to enhance the content extensibility and ease of use of the e-deposit system including extended reality content, and to advance and construct spaces for reproducing extended reality content.

• Phonetics and Speech Sciences
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• v.16 no.2
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• pp.99-109
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• 2024

Coarticulation is affected by the continuous movement of the articulator within a limited time and space through the neighboring segments and various overlaps. This study investigated the differences in coarticulation characteristics of children with reading disabilities and nondisabled children in CVC and VCV syllables consisted of stops, affricates, and vowels (a, i, u). The subjects were 13 children with reading disabilities and nondisabled children in the 2nd to 6th grades in elementary school. Two second formants were measured. One was measured at the point where the vowel began, and the other was measured at the mid point of the vowel stable section. Regression analysis was performed with F2 onset and F2 of the following vowel to obtain the locus equation (LE). 3-way ANOVA was conducted to the slope of the LE according to the groups (reading disabilities vs. nondisabled), places of articulation, and phonation types. In CVC syllable, dyslexic children showed a flatter slope than nondisabled children. With respect to the places of articulation, velar or bilabial sounds showed steeper LE slope than alveolar or palatal sounds. There were no main effects regarding group and phonation types variable for VCV syllable, and the significant differences in the places of articulation were also differed from the results for the CVC syllables. This study confirmed that dyslexic children showed a different pattern of coarticulation slope depending on the syllable structure. We also found that the higher pause rate of the dyslexic children had a stronger effect on the coarticulation in VCV structures.

• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.132-142
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• 2009

The Tamar rift valley runs through the City of Launceston, Tasmania. Damage has occurred to city buildings due to earthquake activity in Bass Strait. The presence of the ancient valley, the Tamar valley, in-filled with soft sediments that vary rapidly in thickness from 0 to 250mover a few hundreds metres, is thought to induce a 2D resonance pattern, amplifying the surface motions over the valley and in Launceston. Spatially averaged coherency (SPAC), frequency-wavenumber (FK) and horizontal to vertical spectrum ratio (HVSR) microtremor survey methods are combined to identify and characterise site effects over the Tamar valley. Passive seismic array measurements acquired at seven selected sites were analysed with SPAC to estimate shear wave velocity (slowness) depth profiles. SPAC was then combined with HVSR to improve the resolution of these profiles in the sediments to an approximate depth of 125 m. Results show that sediments thicknesses vary significantly throughout Launceston. The top layer is composed of as much as 20m of very soft Quaternary alluvial sediments with a velocity from 50 m/s to 125 m/s. Shear-wave velocities in the deeper Tertiary sediment fill of the Tamar valley, with thicknesses from 0 to 250m vary from 400 m/s to 750 m/s. Results obtained using SPAC are presented at two selected sites (GUN and KPK) that agree well with dispersion curves interpreted with FK analysis. FK interpretation is, however, limited to a narrower range of frequencies than SPAC and seems to overestimate the shear wave velocity at lower frequencies. Observed HVSR are also compared with the results obtained by SPAC, assuming a layered earth model, and provide additional constraints on the shear wave slowness profiles at these sites. The combined SPAC and HVSR analysis confirms the hypothesis of a layered geology at the GUN site and indicates the presence of a 2D resonance pattern across the Tamar valley at the KPK site.

• Journal of the Korean Geographical Society
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• v.28 no.3
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• pp.213-226
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• 1993

In Korea, the urban studies of geography have mainly dealt with such a series of research as system of urban place and internal structure of urban area. The existing studies have been carried out with ecological approach. Ecologists, now a days, regard organiation and transfor-mation of the urban space as the process of invasion, succession, and segregation. However it is more proper that cities should be considered not as fragmantary objects, as some ecologists insist, but as synthetic ones in social structure. This research, with adopting a case of the renewasl of central area in Seoul, tried to make it clear that the formation and transition of the city is a product of social structure and examined polical and economic logic which exists in variation of urban space in detail. The results of this study are as follows; Urban renewal of central area is closely related with production and reproduction in capitalist society. In urban center, as business activities had increased since 1973 due to decen-tralization of production process, the necessity of reorganizing the land use in existing central area accordingly increased. The urban renewal program of central area in Seoul was inrroduced under such situation. The urban renewal of central area reflecting the capital logic has changed the central area with six hundred year's tradition. From the urban renewal of central area, not only was the central area, which traditionally had been mixed with various fun-ctions, simplified into the unitary area of busi-ness, but also physical landscape changed. As the land lot in renewal area expanded into regular shape, buildings became larger and taller. The program tremendously raised the price of related area. Aiming at these profits caused by the raised price, a great number of capitalists participated in the program. And as the benefit ratio of the manufacture sector continuously dropped with the economic recession, the pro-gram was carried out much more vigorously. That was because the idle capital accumulated during the recession was invested in property sector and was self-proliferated. The urban renewal raised the land value of central area and drove out the people living in this area. The people moved into the whole parts of the city resulting diffused squatter settlements. And the urban changes in central area were results of the policy of municipal authorities, who supported and systematized the changes lawfully and administratively, as well as reali-zation of capital logic. Due to the renewal policies of central area in Seoul, much more renewals by the only capitalists were carried out than those by the people themselves living in that area. The integration of land ownership in the law of urban renewal shows the reason of that. Moreover, the law allows the third deve-loper to participate in the tasks and admits the land expropriation rights. The municipal autho-rities guaranteed the profitability of the tasks through finacial aid, tax benifit, and relaxation of regulations for construction. As examined above, the changes in the land use of urban space have been led not by the ecological process of development of the city itself, but by the restructuring of capitalism and the intervention of the government authorities.