• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.51-56
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• 2019

Biofilms facilitate communication among microorganisms for nutrients and protect them from predators and harmful chemicals such as antibiotics and detergents. Biofilms can also act as cores for the development of clogs in many agricultural irrigation systems and in porous media. In this study, we deployed glass units at a depth of 20 m below the ground surface in the groundwater-surface water mixing zone, and retrieved them after 4 months to investigate the potential colonization of indigenous microbial community and possible mineral-microbe assemblages. We observed the periodic formation of microbial colonies by fluorescence dye staining and microscopy, and analyzed the composition of the microbial community in both the mineral-microbe aggregates and groundwater, by next generation sequencing of the 16S rRNA gene amplicons using MiSeq platform. During the course of incubation, we observed an increase in both the mineral-microbe aggregates and content of extracellular polymeric substances. Interestingly, the microbial community from the aggregates featured a high abundance of iron redox-related microorganisms such as Geobacter sp., Comamonadaceae sp., and Burkholderiales incertae sedis. Therefore, these microorganisms can potentially produce iron-minerals within the sediment-microbe-associated aggregates, and induce biofilm formation within the groundwater borehole and porous media.

• Computers and Concrete
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• v.23 no.5
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• pp.361-376
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• 2019

In this research, bending analysis of a micro sandwich skew plate with isotropic core and piezoelectric composite face sheets reinforced by carbon nanotube on the elastic foundations are studied. The classical plate theory (CPT) are used to model micro sandwich skew plate and to apply size dependent effects based on modified strain gradient theory. Eshelby-Mori-Tanaka approach is considered for the effective mechanical properties of the nanocomposite face sheets. The governing equations of equilibrium are derived using minimum principle of total potential energy and then solved by extended Kantorovich method (EKM). The effects of width to thickness ratio and length to width of the sandwich plate, core-to-face sheet thickness ratio, the material length scale parameters, volume fraction of CNT, the angle of skew plate, different boundary conditions and types of cores on the deflection of micro sandwich skew plate are investigated. One of the most important results is the reduction of the deflection by increasing the angle of the micro sandwich skew plate and decreasing the deflection by decreasing the thickness of the structural core. The results of this research can be used in modern construction in the form of reinforced slabs or stiffened plates and also used in construction of bridges, the wing of airplane.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.45.3-46
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• 2018

Oscillations in a sunspot are easily detected through the Doppler velocity observation. Although the sunspot oscillations look erratic, the wavelet analysis show that they consist of successive wave packets which have strong power near three or five minutes. Previous studies found that 3-min oscillation at the chromosphere is a visual pattern of upward propagating acoustic waves along the magnetic field lines. Resent multi-height observations help this like vertical study, however, we also focus on horizontal facet to extend three dimensional understand of sunspot waves. So, we investigate a fragmented sunspot expected to have complex wave profiles according to the positions in the sunspot observed by the Fast Imaging Solar Spectrograph. We choose 4 points at different umbral cores as sampling positions to determine coherence of oscillations. The sets of cross-correlation with three and five minutes bandpass filters during a single wave packet reveal interesting results. Na I line show weak correlations with some lags, but Fe I and Ni I have strong correlations with no phase difference over the sunspots. It is more remarkable at Ni I line with 3-min bandpass that all sets of cross-correlation look like the autocorrelation. We can interpret this as sunspot oscillations occur spontaneously over a sunspot at photosphere but not at chromosphere. It implies a larger or deeper origin of 3-min sunspot oscillation.

• Design & Manufacturing
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• v.15 no.3
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• pp.39-44
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• 2021

In molding of continuous fiber-reinforced thermoplastic composites, it is very difficult to impregnate between the reinforcements and the matrix since the matrix has a high melting temperature and high viscosity. Therefore, most of composite molding processes are divided in the manufacturing processes of intermediate materials called prepreg and the forming of products from intermediate materials. The divided process requires additional facilities and thermoforming, and they increase the cycle time and cost of composite products. These problems can be resolved by combining the continuous fiber-reinforced composite molding process with injection molding. However, when a composite material is manufactured by inserting woven fabric into the injection mold, poor impregnation occurs on the surface of the molded product. It affects the properties of the composites. In this paper, through an impregnation experiment using cores with different heat transfer rates and pore densities, the reason for the poor impregnation was confirmed, and molding experiments were conducted to produce composite with improved surface impregnation by inserting the mesh. And also, the surface impregnation and deformation of composites molded using different types of mesh were compared with each other.

• Korean Journal of Head & Neck Oncology
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• v.35 no.1
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• pp.41-44
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• 2019

Intraductal papilloma is an extremely rare benign tumor especially when it arises from major salivary gland. Recently, we experienced a case of an intraductal papilloma arising from the parotid gland in a 51-year-old woman. The radiologic finding showed lobulated enhancing and cystic solid mass in the left parotid superficial lobe. Superficial parotidectomy was performed. Pathological findings showed papillary proliferations with fibrovascular cores lined with bland cuboidal or columnar epithelial cells, and immunohistochemical stain results were consistent with intraductal papilloma. We report a case of intraductal papilloma in parotid gland with a review of literature.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.5
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• pp.3-10
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• 2019

This study is purposed to analyze of House Vision exhibition and projects in Japan. The contemporary residence has been planned and designed with fixed territory and boundary of rooms. According to the symposium of House Vision, the spatial boundary can be studied in the aspect of territory that molds the experience of residents. So, this study reviews Aldo van Eyck's concept of 'in-between'. Through the analysis, House Vision exhibition is revealed that the housing models present architectural characteristics of middleware and third place. The cognition of internal and external boundary stems from movements and activities of residents. That is the dwelling and residential space determined by users and residents. In this regard, 'in-between' of House Vision has structures(multilayer) causing various relationships to be perceived, so as to connect with the dwelling and activities of residents. As a result, it has relational meanings of sharing, as well as makes possible other community life to be done. According to the projects of House Vision, the units and cores have created the new connections and relationships between privacy and publicity. In conclusion, this research shows a new direction of the spatial strategies on House Vision exhibition in Japan.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.9
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• pp.11-18
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• 2018

As the height of the modular buildings increases, their stability becomes more and more dependent on the core. All traditional construction methods in structural concrete and steel can be utilized for cores in modular buildings but a core system with dry connection is more desirable to complete a greater degree of factory finish and faster erection of modular buildings. In order to do that, the hybrid PC(precast concrete) panel, which has a pair of C-shaped steel beams combined at the top and bottom of a concrete wall, was developed, In this study the cyclic lateral loading test on the hybrid PC panel is carried out and the panel configurations are examined to enhance the structural performance in comparison with the RC wall. Experimental results show that the strength of hybrid PC panel is about 70% of thar ot RC wall and the anchorage of vertical reinforcing bar welded to C-shaped steel beam needs to be improved.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.9
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• pp.151-158
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• 2019

A concrete core is used widely as lateral stability systems in high-rise modular buildings. As an alternative to traditional cast in-situ core, the precast concrete(PC) method can accelerate the construction of reinforced concrete cores. A core composed of precast elements differs from a in-situ core in having connections between the precast elements. The typical vertical connection between PC panels is consisted of shear keys, loop bars, lacer bars and grout. In this study, the effect of vertical connection components on shear strength is investigated experimentally. The test results show that the contribution to the shear strength is greater in order of grout strength, shear keys, lacer bars and loop bars. In addition, the numerical models to estimate the shear strength according to two crack patterns in the vertical joint of the PC panels are derived. The feasibility of the numerical models is evaluated by comparing the estimated shear strength and the test results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.3
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• pp.121-128
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• 2021

Piloti-type buildings in Korea are usually composed of lower frames and upper shear wall structures. Piloti-type buildings have been seriously damaged during earthquakes because of the construction of soft and weak stories. Piloti-type buildings with edge cores are two-way unsymmetric planes. This paper analyzed and obtained the dynamic response for structures modeled using a multistory two-way asymmetric system. The numerical results, obtained using the Newmark-β method, show the time-history responses and trends of maximum displacements and shear forces. The purpose of this study is to evaluate the effect of reinforcement on dynamic response when a shear wall or brace is reinforced in the corner opposite the piloti.

• Bulletin of the Korean Chemical Society
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• v.12 no.2
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• pp.199-206
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• 1991

A statistical thermodynamic theory of thermotropic main-chain polymeric liquid crystalline melts is developed within the framework of the lattice model by a generalization of the well-known procedure of Flory and DiMarzio. According to the results of Vasilenko et al., the theory of orientational ordering in melts of polymers containing rigid and flexible segments in the main chain is taken into account. When the ordering of flexible segments in the nematic melt is correlated with that of rigid mesogenic groups, the former is assumed to be given as a function of the ordering of rigid mesogenic cores. A free energy density that includes short-range packing contributions is formulated. The properties of the liquid-crystalline transiton are investigated for various cases of the system. The results calculated in this paper show not only the order-parameter values but also the first-order phase transition phenomena that are similar to those observed experimentally for the thermotropic liquid-crystalline polymers and show the transitional entropy terms which actually increase upon orientational ordering. In the orientational ordering values, it is shown that mesogenic groups, flexible segments, and gauche energy (temperature) may be quite substantial. Finally, by using the flexibility term, we predict the highly anisotropic mesophase which was shown by Vasilenko et al.