• Journal of the Korean Ceramic Society
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• v.39 no.4
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• pp.367-376
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• 2002

Electrical conduction in $SrZr_{1-x}Y_xO_{3-\delta}$((x=0.05, 0.10)-metal electrode system was investigated by impedance spectroscopy and two-probe d.c. conductivity measurement. Electrode conductivity in anodic direction varies with $P_W^{1/2}$( and that in cathodic direction with $P_{O2}^{1/4}$ in oxidizing atmosphere. In hydrogen atmosphere, the addition of water vapor increased the electrode conductivity both in anodic and cathodic direction. Increasing dopant concentration from 5 to 10% showed a more than four times increase in anodic conduction as well as bulk conduction of the solid electrolyte. This observation implies that unfilled oxygen vacancy concentration increases rapidly as the dopant content increases in humid atmosphere. The activation energy of cathodic conduction in Pt and Ag electrode was nearly same below $800^{\circ}C$ which means the rate of cathodic reaction is determined by the reaction in the electrolyte surface rather than on the metal electrodes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.2
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• pp.17-25
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• 2006

In the present study, a 2-D chimera technique for overlapped bodies in relative motion is developed using unstructured triangular meshes. The solid boundary nodes located next to the intersecting point between bodies are merged to the intersecting point to assure accurate representation of the intersecting region. In order to assign proper value of flow variables at the nodes located out of the computational field, interpolation is conducted for non-active nodes. For validation, the motions of a NACA64A006 airfoil and a NACA0012 airfoil with a plane flap are computed and the results are compared with other simulations. The motion of a launching missile ejected from a NACA0012 airfoil is also simulated.

• Clean Technology
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• v.28 no.2
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• pp.97-102
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• 2022

Lithium sulfur (Li-S) batteries have attracted considerable attention as a promising candidate for next-generation power sources due to their high theoretical energy density, low cost, and eco-friendliness. However, the poor electrical conductivity of sulfur and its insoluble discharging products (Li₂S₂/Li₂S), large volume changes, severe self-discharge, and dissolution of lithium polysulfide intermediates result in rapid capacity fading, low Coulombic efficiency, and safety risks, hindering Li-S battery commercial development. In this study, a three-dimensionally (3D) connected hierarchical porous carbon framework (HPCF) derived from waste sunflower seed shells was synthesized as a sulfur host for Li-S batteries via a chemical activation method. The natural 3D connected structure of the HPCF, originating from the raw material, can effectively enhance the conductivity and accessibility of the electrolyte, accelerating the Li⁺/electron transfer. Additionally, the generated micropores of the HPCF, originated from the chemical activation process, can prevent polysulfide dissolution due to the limited space, thereby improving the electrochemical performance and cycling stability. The HPCF/S cell shows a superior capacity retention of 540 mA h g^-1 after 70 cycles at 0.1 C, and an excellent cycling stability at 2 C for 700 cycles. This study provides a potential biomass-derived material for low-cost long-life Li-S batteries.

• Korean Journal of Head & Neck Oncology
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• v.7 no.2
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• pp.104-113
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• 1991

선양낭암은 타액선종양중 비교적 드문 악성종양으로 병리조직학적 및 임상적으로 독특한 양상을 보인다. 병리조직학상 종양세포가 신경주변으로 침범하여 수술당시 적절한 수술연을 얻기 어렵고 이에 따른 국소재발이 거듭되고 임파선전이 및 예측치 않는 원격전이가 생기기도 한다. 지금까지 선양낭암환자의 예후에 영향을 미치는 여러 요인들에 대한 연구들이 이루워지고 있는데 그중 조직학적 분화도, 원발부위, 종양의 크기, 수술연의 상태와 임상적 병기들이 중요시되고 있다. 이에 저자들은 1960년부터 1980년 까지 텍사스대학 M.D. Anderson 암센터에서 치료받은 이하선 및 악하선 선양낭암 각각 13례와 26례를 대상으로 원발부위가 환자의 생존 및 치료에 미치는 영향을 알고자 다른 예후인자로 알려진 조직병리학적 소견들과 함께 통계학적 분석을 실시하였다. 이하선과 악하선에 생긴 선양낭암을 비교한 결과 이하선에 생긴 경우 조직학적 분화도가 더 낮았고 악하선 종양에서 수술연에 종양침범율이 더 적었다. 경부 임파절 전이는 악하선 종양에서 많았으나 반면 원격전이는 이하선 종양에서 더 많이 발생하였다. 그러나 종양의 크기, 선경주위침범 유무, 국소재발과 환자의 생존율사이에는 의의있는 상관 관계는 없었다. 이하선과 악하선에 생긴 선양낭암의 여러 특성들과 생존률간의 univariate 분석결과 악하선에 생긴 선양낭암 환자에서 종양이 크거나 조직학상 분화가 나쁘거나(solid pattern), 경부임파절 전이와 원격전이가 생기면 예후에 나쁜 영향을 끼침이 밝혀졌다. 그러나 이하선에 생긴 경우 분석례가 너무 적어 결론을 내리기에 불충분하였다. 원발부위에 따른 선양낭암 환자들의 특성을 chi-square 검정법을 이용하여 통계학적으로 분석한 결과 이 두군간에는 의의있는 통계학적 차이는 발견할 수 없었다.

• Biomedical Science Letters
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• v.20 no.2
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• pp.85-95
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• 2014

Activation of the epidermal growth factor receptor (EGFR) and downstream signaling pathways have been implicated in causing resistance to EGFR-targeted therapy in solid tumors, including the head and neck tumors. To investigate the mechanism of antiproliferation to EGFR inhibition in oral cancer, we compared EGFR tyrosine kinase inhibitor (Gefitinib, Iressa, ZD1839) with respect to its inhibitory effects on three kinases situated downstream of EGFR: MAPK, Akt, and glycogen synthase kinase-$3{\beta}$ (GSK-$3{\beta}$). We have demonstrated that ZD1839 induces growth arrest and apotosis in oral cancer cell lines by independent of EGFR-mediated signaling. An exposure of oral cancer cells to ZD1839 resulted in a dose dependent up-regulation of the cyclin-dependent kinase inhibitor p21 and p27, down regulation of cyclin D1, inactivation of GSK-$3{\beta}$ and of active MAPK. In resistant cells, GSK-$3{\beta}$ is constitutively active and its activity is negatively regulated primarily through Ser 9 phosphorylation and further enhanced by Tyr216 phosphorylation. These results showed that the resistance to the antiproliferative effects of ZD1839, in vitro was associated with uncoupling between EGFR and MAPK inhibition, and that GSK-$3{\beta}$ activation and degradation of its target cyclin D1 were indicators of high cell sensitivity to ZD1839. In conclusion, our data show that the uncoupling of EGFR with mitogenic pathways can cause resistance to EGFR inhibition in oral cancer.

• Journal of the Korean Society of Costume
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• v.33
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• pp.41-54
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• 1997

The objectives of this study were to find out the relationships between clothing style pre-ferences and self-image and to examine the differences in clothing style preferences ac-cording to marital status educational level and social stratification of women. The drawings of clothing style were designed referring to the catalogues for spring/summer of 1996 and printed by computer 6 styles of suit corresponding to clothing image were selected. Style A is a brown suit decorated with scarf style B a grey suit with stripes C a yellow suit with printed pattern D a grey and beige suit E a chanel suit decorated with corsage and F a blue suit with pleated skirt. The self-image was separated to the actual self-image and the ideal self-image. Samples were 226 women(ages 18 to 37) in Seoul Korea. The results of the study were the followings. 1. Clothing images of 6 styles were estimated; Style A was plain conservative formal and gentle image ; B masculine solid actual dark and plain image; C feminine romantic bright and splendid image; D actual ordinary un-fashionable and plain image; E feminine ten-der romantic and non-active image ; F indi-vidual fshionable open casual sprightly and active image. 2. There were significant relationships be-tween clothing style preferences and realistic self-image. The women who considered them-selves as masculine preferred style B mascu-line and plain image. The women feminine and conservative preferred style E feminine and tender image. The women not to follow the fshion preferred style D ordinary and plain image. The women informal and open pre-ferred the style F casual and active image. 3. There were significant relationships be-tween clothing style preferences and ideal self-image. The women who wanted to be-tween clothing style preferences and ideal self-image. The women who wanted to be con-sidered themselves as feminine and conserva-tive preferred style E feminine and tender im-age. The women who wanted gentle and con-servative preferred style D ordinary and plain image. The women who wanted sprightly pre-ferred the style F casual and active image. 4. There were significant differences in clothing style preferences according to marital status educational level and social stratifi-cation. The women with more eduacation pre-ferred the splendid and the plain image at the same time. The upper class preferred feminine image and lower class casual and active image.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.2
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• pp.497-501
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• 2008

3D facial scanner for an accurate analysis is measured precisely a distance in straight, a distance in curved line, an angle in 3D data, the area of surface. We can easy acquire 3D data by the method of 0.8sec in each scan with easy handling, simple merge to whole face, harmless and fast process. In the HyungSang medicine, the inspection of the facial shape includes the Dam(gall bladder) - Bang Kwang(urinary bladder) body, the Jung${\cdot}$Gi${\cdot}$Shin${\cdot}$Hyul, the six merdian types etc. And we will collect the evidence based date verifing in the HyungSang clinical medicine. As we will analyze the facial whole form and the size${\cdot}$length${\cdot}$angle of the facial part, put the facial form's standardization on a solid foundation.

• Transactions on Electrical and Electronic Materials
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• v.13 no.6
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• pp.283-286
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• 2012

(1-X)$(Na_{0.5}K_{0.5})NbO_3-XK_{5.4}Cu_{1.3}Ta_{10}O_{29}$ (NKN-KCT) lead-free piezoelectric ceramics have been synthesized by the conventional solid state sintering method, and their sinterability and piezoelectric properties were investigated. Typically, this material is sintered between 1,025 and $1,100^{\circ}C$ for 2 hours to achieve the required densification. Crystalline structures and Microstructures were analyzed by X-ray diffraction and scanning electron microscope. The density, dielectric constant (${\varepsilon}_r$), piezoelectric constant $d_{33}$, electromechanical coupling factor $k_p$ and mechanical quality factor $Q_m$ value of the NKN ceramics depended upon the KCT content and the sintering temperature. In particular, the KCT addition to NKN greatly improved the mechanical quality factor $Q_m$ value. The ceramic with X = 1.0 mol% sintered at $1,050^{\circ}C$ exhibited optimum properties (${\varepsilon}_r$=246, $d_{33}$=95, $k_p$=0.38 and $Q_m$=1,826). These results indicate that the ceramic is a promising candidate material for applications in lead free piezoelectric transformer and filter materials.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.3
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• pp.348-363
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• 2013

The use of I-Core sandwich panel has increased in cruise ship deck structure since it can provide similar bending strength with conventional stiffened plate while keeping lighter weight and lower web height. However, due to its thin plate thickness, i.e. about 4~6 mm at most, it is assembled by high power $CO_2$ laser welding to minimize the welding deformation. This research proposes a volumetric heat source model for T-joint of the I-Core sandwich panel and a method to use shell element model for a thermal elasto-plastic analysis to predict welding deformation. This paper, Part I, focuses on the heat source model. A circular cone type heat source model is newly suggested in heat transfer analysis to realize similar melting zone with that observed in experiment. An additional suggestion is made to consider negative defocus, which is commonly applied in T-joint laser welding since it can provide deeper penetration than zero defocus. The proposed heat source is also verified through 3D thermal elasto-plastic analysis to compare welding deformation with experimental results. A parametric study for different welding speeds, defocus values, and welding powers is performed to investigate the effect on the melting zone and welding deformation. In Part II, focuses on the proposed method to employ shell element model to predict welding deformation in thermal elasto-plastic analysis instead of solid element model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.365-373
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• 2015

In this paper, a planar antenna with monopole-like radiation pattern for on-body communications is proposed. The proposed antenna consists of three split-rings(SR) to generate a monopole-like radiation characteristic. To account for the on-body application, the proposed antenna is designed to have a low-profile. The antenna has an overall dimensions of $0.29{\lambda}_0{\times}0.29{\lambda}_0{\times}0.008{\lambda}_0$ at 5.8 GHz industrial, scientific, and medical(ISM) band(5.725~5.875 GHz). To verify the body effect, a two-thirds muscle equivalent semi solid phantom is fabricated and used to measure the antenna performance. The 10-dB return loss bandwidth is 280 MHz(5.68~5.96 GHz) and the measured peak gain is 1.91 dBi.