• Korean Journal of Materials Research
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• v.22 no.2
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• pp.91-96
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• 2012

AC and ZnS modified $TiO_2$ composites (AC/ZnS/$TiO_2$) were prepared using a sol-gel method. The composite obtained was characterized by Brunauer-Emmett-Teller (BET) surface area measurements, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, scanning electron microscope (SEM) analysis, and according to the UV-vis absorption spectra (UV-vis). XRD patterns of the composites showed that the AC/ZnS/$TiO_2$ composites contain a typical single and clear anatase phase. The surface properties as observed by SEM present the characterization of the texture of the AC/ZnS/$TiO_2$ composites, showing a homogenous composition in the particles showing the micro-surface structures and morphology of the composites. The EDX spectra of the elemental identification showed the presence of C and Ti with Zn and S peaks for the AC/ZnS/$TiO_2$ composite. UV-vis patterns of the composites showed that these composites had greater photocatalytic activity under visible light irradiation. A rhodamine B (Rh.B) solution under visible light irradiation was used to determine the photocatalytic activity. The degradation of Rh.B was determined using UV/Vis spectrophotometry. An increase in the photocatalytic activity was observed. From the photocatalytic results, the excellent activity of the Y-fullerene/$TiO_2$ composites for the degradation of methylene blue under visible irradiation could be attributed to an increase in the photo-absorption effect caused by the ZnS and to the cooperative effect of the AC.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.11 no.2
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• pp.203-212
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• 2004

Purpose: This study was done to determine whether providing auditory and vestibular stimulation to preform infants would have an effect on stress hormones. Methods: The design was a nonequivalent control group protest-posttest design in a quasi-experimental study Seventy-nine preform infants were assigned either one of two experimental groups or to a control group: 27 in the auditory stimulation group, 25 in the vestibular stimulation group and 27 in the control group. The criteria for inclusion in this study were 1) gestational age of less than 37 weeks, 2) birth weight of less than 2,500g, 3) the absence of congenital anomalies or specific diseases, 4) recovering physiological weight loss, and 5) weaned from ventilatory assistance or oxygen. The data were collected from March 2002 to May 2003. The auditory stimulation, a music audiotape, was provided 20 minutes twice a day for 10 days and the vestibular stimulation, an infant waterbed, was provided for 10 days. On day 1 and day 10 of the study, 24 hour urine sample was collected for norepinephrine, epinephrine, and cortisol assays. In the data analysis SPSSWIN 10.0 program was utilized for descriptive statistics, ANOVA and t-test. Results: General characteristics of the three groups showed no significant differences, thus three groups were found to be homogenous. The 24 hour urine cortisol for the auditory (t=3.489, p=.001) and for the vestibular (t=2.638, p=.013) stimulation group were significantly reduced compared to the control group after 10 days. Conclusions: The results suggest that auditory and vestibular stimulation can be used to reduce 24 hour urine cortisol in preform infants. Therefore, music audiotapes and waterbeds provided in incubator are be recommended for reduction of the stress in preform infants who are hospitalized in neonatal intensive care units.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1423-1428
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• 2006

In this study, we have prepared pitch binded AC (activated carbon)/$AC/TiO_2$ composites photocatalysts through carbon tetrachloride solvent method. The developed samples were characterized with surface properties, structural crystallinity between AC and $AC/TiO_2$, elemental identification and photocatalytic activity. The results of the textural surface properties demonstrate that there are slight increases in the BET surface area and adsorbed volume from adsorption isotherm of composite samples with increasing of the amount of AC. The SEM results present to the characterization of porous texture on the pitch/AC/$AC/TiO_2$ composites and homogenous compositions in the particle for all the materials used. From XRD data, a weak and broad carbon peak of graphene remained rutile peaks kept with anatase structure were observed in the X-ray diffraction patterns for the pitch/AC/$AC/TiO_2$ composites. The EDX spectra show the presence of C, O and S with strong Ti peaks. Most of these samples are richer in carbon and major Ti metal than any other elements. Finally, the excellent photocatalytic activity of the pitch/AC/$AC/TiO_2$ composites between relative concentration ($c/c_o$) of MB and UV irradiation time could be attributed to the both effects between photocatalysis of the supported $AC/TiO_2$ and adsorptivity of the two kinds of carbons.

• Steel and Composite Structures
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• v.21 no.1
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• pp.1-36
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• 2016

In the present study, the nonlinear magneto-electro-mechanical free vibration behavior of rectangular double-bonded sandwich microbeams based on the modified strain gradient theory (MSGT) is investigated. It is noted that the top and bottom sandwich microbeams are considered with boron nitride nanotube reinforced composite face sheets (BNNTRC-SB) with electrical properties and carbon nanotube reinforced composite face sheets (CNTRC-SB) with magnetic fields, respectively, and also the homogenous core is used for both sandwich beams. The connections of every sandwich beam with its surrounding medium and also between them have been carried out by considering Pasternak foundations. To take size effect into account, the MSGT is introduced into the classical Timoshenko beam theory (CT) to develop a size-dependent beam model containing three additional material length scale parameters. For the CNTRC and BNNTRC face sheets of sandwich microbeams, uniform distribution (UD) and functionally graded (FG) distribution patterns of CNTs or BNNTs in four cases FG-X, FG-O, FG-A, and FG-V are employed. It is assumed that the material properties of face sheets for both sandwich beams are varied in the thickness direction and estimated through the extended rule of mixture. On the basis of the Hamilton's principle, the size-dependent nonlinear governing differential equations of motion and associated boundary conditions are derived and then discretized by using generalized differential quadrature method (GDQM). A detailed parametric study is presented to indicate the influences of electric and magnetic fields, slenderness ratio, thickness ratio of both sandwich microbeams, thickness ratio of every sandwich microbeam, dimensionless three material length scale parameters, Winkler spring modulus and various distribution types of face sheets on the first two natural frequencies of double-bonded sandwich microbeams. Furthermore, a comparison between the various beam models on the basis of the CT, modified couple stress theory (MCST), and MSGT is performed. It is illustrated that the thickness ratio of sandwich microbeams plays an important role in the vibrational behavior of the double-bonded sandwich microstructures. Meanwhile, it is concluded that by increasing H/lm, the values of first two natural frequencies tend to decrease for all amounts of the Winkler spring modulus.

• International Journal of Industrial Entomology and Biomaterials
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• v.33 no.2
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• pp.85-91
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• 2016

Exosomes are homogenous vesicles of 40-100 nm diameter produced endogenously. Exosomes are generated by inward budding into multi-vesicular bodies (MVB) and then released to extracellular space. Exosomes contain various nucleic acid and protein cargoes from their cells of origin and this endosomal cellular molecules are used for intracellular communication and for both promotion and suppression of immune responses. Recently, they are also considered as delivery vehicle for therapeutic proteins due to their characteristics of stability in body fluids and ability for target uptake. Also, they show less immune reactivity because the isolated exosome harboring therapeutic proteins can be from the same host. White-spotted flower chafer, Protaetia brevitarsis is one of the major insect commercially reared in Korea. There are bacterial and fungal pathogens causing diseases in the beetle, and these diseases incur economic loss to the larva-rearing farms. Due to their endosomal cargoes, exosomes are good candidates in use of disease diagnosis. In this study, we isolated insect exosome from the hemolymph of P. brevitarsis, and verified it by analysis of the exosome-specific surface proteins and RNA.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.31.1-31.1
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• 2009

In an approach to acclimate ourselves torecent ecological consciousness trend, a lead-free piezoelectric material, bismuth sodium titanate (abbreviated as BNT) based bismuth sodium barium titanate (abbreviated as BNT-BT), was considered as an environment-friendly alternative for a lead based piezoelectric system. Ceramic specimens of0.94[(BixNa0.5)TiO3]-0.06[BaTiO3] (x = 0.500~0.515) compositions were prepared by a modified mixed oxide method. To increase the chemical homogeneity andre action activity, high energy mechanical milling machine and pre-milled nanosized powder has been used. In this method (BixNa0.5)TiO3 (x=0.500~0.515) andBaTiO3 were prepared separately from pre-milled constituent materials at low calcination temperature and then separately prepared BNTX (X=1, 2, 3 and 4) and BT were mixed by high energy mechanical milling machine. Without further calcination step the mixed powders were pressed into disk shape and sintered at $1110^{\circ}C$. Microstructures, phase structures and electrical properties of the ceramic specimens were systematically investigated. Highly dense ceramic specimens with homogenous grains were prepared in spite of relatively low sintering temperature. Phase structures were not significantly influenced by the excess amount Bi. Large variation on the piezoelectric and dielectric properties was detected at relative high excess Bi amounts. When $x{\leq}0.505$, the specimens exhibit insignificant variation in piezoelectric and dielectric constant though depolarization temperature is found to be decreased. Considerable amount of decrease in piezoelectric and dielectric properties are observed with higher excess of Bi amounts ($x{\geq}0.505$). This research indicates the advantages of high energy mechanical milling and importance of proper maintenance of Bi stoichiometry.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.1-12
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• 2005

A Mobile manipulator - a serial connection of a mobile robot and a task robot - is a very useful system to achieve various tasks in dangerous environment. because it has the higher performance than a fixed base manipulator in regard to the size of it's operational workspace. Unfortunately the use of a mobile robot introduces non-holonomic constraints, and the combination of a mobile robot and a manipulator generally introduces kinematic redundancy. In this paper, first a method for estimating the position of object at the cartesian coordinate system acquired by using the geometrical relationship between the image captured by 2-DOF active camera mounted on mobile robot and real object is proposed. Second, we propose a method to determine a optimal path between current the position of mobile manipulator whose mobile robot is non-holonomic and the position of object estimated by image information through the global displacement of the system in a symbolic way, using homogenous matrices. Then, we compute the corresponding joint parameters to make the desired displacement coincide with the computed symbolic displacement and object is captured through the control of a manipulator. The effectiveness of proposed method is demonstrated by the simulation and real experiment using the mobile manipulator.

• The Journal of the Korean dental association
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• v.53 no.2
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• pp.143-152
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• 2015

Ultrasonography is relatively inexpensive, non-invasive imaging tool and provides real-time imaging. In addition, the images can be obtained repeatedly. But it is not widely used by dentists because it is hard to interpret and technique sensitive. Above all, ultrasonography cannot be used for hard tissue diagnosis. However, ultrasonography can be applied for diagnosis of infection, soft tissue tumor and inflammatory muscle diseases which are commonly found in dental outpatients. Generally, it shows well-defined border, hypoechoic and homogenous structure in case of benign tumor. Malignant tumor appears relatively irregular margin and heterogenous structure. Cyst represents relatively echo-free features compared with benign tumor. Although the general characteristics of abscess are similar with benign tumor, we can observe an increased vascularity and different clinical features. The purpose of this report is to present 3 cases of US images using office-based ultrasonography with their features and discuss the role of office-based ultrasound in dentistry for diagnosis of soft tissue lesions with literature review.

• Korean Journal of Biological Psychiatry
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• v.12 no.2
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• pp.216-220
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• 2005

Background:Brain-derived neurotrophic factor(BDNF) genes are thought to be important factors in some personality traits. The goal of this study was to determine the role of these genes in personality traits. Method:The participants included 170 healthy adults with no history of psychiatric disorders and other physical illnesses for the last 6 months. All participants were tested by the Temperament and Character Inventory (TCI). BDNF Val64Met gene polymorphisms were analyzed with PCR(Polymerase Chain Reaction). Differences on TCI dimensions and sub-scales among groups were examined with ANOVA. Result:There was a significant correlation between BDNF Val64Met and Persistence(PS)(p=0.036) in female subjects, but none with the other TCI dimensions. A post-hoc comparison revealed significant a difference between Val/Val and Met/Met (p=0.031). Conclusion:Our study suggests that the BDNF Val64Met gene polymorphism is associated with persistence in Korean female subjects, but the small number of subjects limits generalization of our results. Further studies with a larger number of homogenous subjects are needed to confirm whether the BDNF gene is related to personality traits.

• Composites Research
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• v.24 no.4
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• pp.41-47
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• 2011

This paper deals with anisotropic property and structural analysis for short fiber reinforced plastic composites manufactured by the injection molding process. The common approach for modeling this type of material is the consideration of the material as homogenous and isotropic. However, the common isotropy approach often results in unexpected failure. To overcome this, new structure analysis methodology was developed in order to consider fiber orientation effect using injection mold flow analysis and Halpin-Tsai equations for unidirectional composites and taking an orientation average. The numerical predictions are compared to experimental data for tensile specimen. The predicted mechanical properties agree well with experimental data for fiber orientation and weld line effect. The analysis system was also applied to an automobile part. The proposed anisotropic model predicted different mechanical properties by position of the part and different mechanical performance of the part was changed according to injection gate position.