• 한국재료학회지
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• 제33권11호
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• pp.447-457
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• 2023

Single-atom Pd clusters anchored on t-BaTiO₃ material was synthesized using hydrothermal and ultrasonic methods for the effective piezoelectric catalytic degradation of pollutants using vibration energy. XRD patterns of BaTiO₃ loaded with monoatomic Pd were obtained before and after calcining, and showed typical cubic-phase BTO. TEM and HAADF-STEM images indicated single-atom Pd clusters were successfully introduced into the BaTiO₃. The piezoelectric current density of the prepared Pd-BaTiO₃ binary composite was significantly higher than that of the pristine BaTiO₃. Under mechanical vibration, the nanomaterial exhibited a tetracycline decomposition rate of ~95 % within 7 h, which is much higher than the degradation rate of 56.7 % observed with pure BaTiO₃. Many of the piezo-induced electrons escaped to the Pd-doped BaTiO₃ interface because of Pd's excellent conductivity. Single-atom Pd clusters help promote the separation of the piezo-induced electrons, thereby achieving synergistic catalysis. This work demonstrates the feasibility of combining ultrasonic technology with the piezoelectric effect and provides a promising strategy for the development of ultrasonic and piezoelectric materials.

• Journal of the Optical Society of Korea
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• 제18권3호
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• pp.274-282
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• 2014

In this study, closely spaced Au nanoparticles which are arranged in nanocluster (heptamer) configurations have been employed to design efficient plasmonic subwavelength devices to function at the telecommunication spectrum (${\lambda}$~1550 nm). Utilizing two kinds of nanoparticles, the optical properties of heptamer clusters composed of Au rod and shell particles that are oriented in triphenylene molecular fashion have been investigated numerically, and the cross-sectional profiles of the scattering and absorption of the optical power have been calculated based on a finite-difference time-domain (FDTD) method. Plasmon hybridization theory has been utilized as a theoretical approach to characterize the features and properties of the adjacent and mutual heptamer clusters. Using these given nanostructures, we designed a complex four-branch ($1{\times}4$) Y-shape splitter that is able to work at the near infrared region (NIR). This splitter divides and transmits the magnetic plasmon mode along the mutual heptamers arrays. Besides, as an important and crucial parameter, we studied the impact of arm spacing (offset distance) on the guiding and dividing of the magnetic plasmon resonance propagation and by calculating the ratio of transported power in both nanorod and nanoshell-based structures. Finally, we have presented the optimal structure, that is the four-branch Y-splitter based on shell heptamers which yields the power ratio of 23.9% at each branch, 4.4 ${\mu}m$ decaying length, and 1450 nm offset distance. These results pave the way toward the use of nanoparticles clusters in molecular fashions in designing various efficient devices that are able to be efficient at NIR.

• 대한치과의사협회지
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• 제55권5호
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• pp.339-350
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• 2017

The aim of the study was to analyze the distribution of dental filling materials for carious permanent teeth of school children in a city. The study was designed as time-serial study, using the data of the dental survey for children aged 8-, 10- and 12-year children living in Gimhae city. The samples were selected by stratified clusters sampling. The number of surveyed samples in depth-analysis for types of dental filling materials were 567 in 2009 and 331 in 2013, respectively. They had dental restorations on one or more teeth. The changing pattern of used dental filling materials was analyzed between 2009 and 2013. Statistical analysis was conducted according to variables related to dental filling material type; DMFT and DMFS index, number of fissure sealed teeth and surface and surveyed year. Amalgam filling rate decreased from 27.9% in 2009 to 18.8% in 2013, while filling rate of tooth-colored materials increased from 56.1% in 2009 and 68.9% in 2013. Amalgam filling rate was a negative correlation with filling rate of tooth-colored materials or gold and number of fissure sealed teeth and a positive correlation with DMFT index. Filling rate of tooth-colored materials was a negative correlation with filling rate of amalgam or gold and DMFT index and a positive correlation with number of fissure sealed teeth. The light-curing composite resin should be included in the reimbursement range of National Health Insurance to solve an inequity of dental health care services.

• Applied Microscopy
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• 제42권3호
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• pp.124-128
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• 2012

Leaf surface structures were investigated in the Chinese juniper Juniperus chinensis by scanning electron microscopy. Adult scale leaves were collected from the tree, air-dried at room temperature, and sputter-coated with gold without further specimen preparation. Approximately fi ve stomata were locally distributed and arranged in clusters on the leaf surface. Stomata were ovoid and ca. 40 ${\mu}m$ long. The epicuticular wax structures of J. chinensis leaves were tubules and platelets. Numerous tubules were evident on the leaf regions where stomata were found. The tubules were cylindrical, straight, and ca. 1 ${\mu}m$ in length. They almost clothed the stomatal guard cells, and occluded the slit-shaped stomatal apertures. Moreover, the wax ridges were flat crystalloids that were connected to the surface by their narrow side. They did not have distinct edges, and their width/height ratio varied. In particular, the wax ridges could be discerned on the leaf regions where stomata were not present nearby. Since the wax ridges did not have distinct edges on their margin, they were identified as platelets. Instances were noted where platelets were oriented either parallel to each other or perpendicular to the cuticle surface. These results can be used in biomimetics to design the hierarchical structures for mimicking the plant innate properties such as hydrophobicity and self-cleaning effects of the leaf surface.

• 복식
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• 제53권4호
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• pp.1-16
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• 2003

The purpose of this study is to investigate the sensibility images of Korean Traditional Chumoni. The detailed methodology of this study is as follows. Selections of stimuli to analyse the sensibility images of Korean Traditional Chumoni were made up of 15 stimuli. The survey has been done for the 15 slide stimuli with semantic differential hi-polar scales which are consist of 23 couples of sensibility words. The subjects were 150 female students majoring in clothing and textile. 150 male students majoring in other department and 150 female students majoring in other department in the twenties between 2001. 3. 30 and 2001. 4. 4. The obtained data were analyzed by factor analysis, cluster analysis. ANOVA. The major finds were as follows. 1. To explain the hierarchy of the sensibility of Korean Traditional Chumoni, two image groups were classified, one is noble and characteristic image the other is splendid and intensive image. Finally it represented noble and splendid image. 2. As result of the factor analysis. 3 factors which are Attraction, Decorativeness, Gravity were found to be constructing factors for the sensibility images of Korean Traditional Chumoni. 3. By cluster analysis, 4 clusters were determined according to Korean Traditional Chumoni. Cluster 1 is splendid. multi-colored and realistic in patteren. Cluster 2 is consist of 'true chumonis' and one-colored. Cluster 3 is modal in pattern. Cluster 4 is simple without any decorations. As to the difference of image of Korean Traditional Chumoni, there were significant differences amang 3 factors by cluster Cluster 1 was found most attractive and grave. Cluster 2 was found most decorative. 4. As to the difference of image of Korean Traditional Chumoni, there were significant differences amang 3 factors by decoration. Gold foil was found most attractive and grave. Embroidery was found most decorative. 5. As to the difference of image of Korean traditional chumoni, there were differences in Decorativeness and Gravity by sex and there were differences in Attraction by major.

• Applied Microscopy
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• 제37권4호
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• pp.249-258
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• 2007

이자섬은 이자를 구성하는 외분비조직에 둘러싸여 존재하는 내분비세포의 집단으로, 이자섬에서 분비되는 인슐린은 $\beta$세포에서 분비되는 호르몬이며, 세포질의 리보좀에서 합성되고 골지체를 경유하여 세포질로 방출되는 기작을 가지고 있다. 충분한 양의 이자섬 이식은 인슐린 의존형 당뇨병인 제1형 당뇨병에서 정상혈당을 회복시키고, 당뇨 합병증을 방지할 수 있는 치료방법으로 사용되고 있다. 하지만 당뇨병 환자에게 이식을 위한 이자섬의 양에 비해 공여자로부터 증여된 이자섬의 양은 제한적이다. 이러한 문제점은 이자섬의 증식으로 연구되고 있으나, 배양된 이자섬이 정상 조직내의 이자섬과 형태적 기능적으로 동일한 것인지에 관한 연구는 미비하였다. 따라서 본 연구에서는 분리된 이자섬과 배양된 이자섬을 구성하는 세포들의 내부구조의 변화를 주사전자현미경, 투과전자현미경을 이용하여 세포의 미세구조를 확인하고, 인슐린 항체를 이용한 $\beta$세포 내의 인슐린 분포양상을 확인하여 다음과 같은 결과를 얻었다. 분리된 이자섬의 $\beta$세포는 일반적인 핵 미토콘드리아, 세포질세망 그리고 인슐린 과립이 분포하고, 배양된 이자섬 $\beta$세포의 경우 분리된 이자섬에 비하여 일반적인 핵의 모습과 부피가 증가한 세포질과 미토콘드리아, 세포질세망 그리고 골지체의 발달이 이루어지는 것으로 관찰되었다. 인슐린 과립의 경우 분리된 이자섬에 비해 감소하며, 세포막 주위에 분포하는 것으로 관찰되었다. 배양된 이자섬에서 관찰되는 인슐린 과립 분포의 변화, 세포질세망의 증가, 골지체의 발달은 배양된 이자섬 $\beta$세포의 인슐린 생성 분비 기능의 향상과 부피의 증가가 이루어지기 위한 세포 내부의 형태적 변화가 이루어지는 것으로 추측된다.