• Journal of Magnetics
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• v.8 no.4
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• pp.129-132
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• 2003

We investigated the crystallographic and magnetic properties of double perovskite $Sr_2Fe_{l-x}Cr_{x}MoO_{6}$ (x=0.0, 0.01, 0.03, 0.05, and 0.10). Mossbauer spectra of the $Sr_2Fe_{l-x}Cr_{x}MoO_{6}$ have been taken at various temperatures ranging from 15 to 415 K. As the temperature increased towards $T_{c}$(415 K), the Mossbauer spectra showed line broadening and 1, 6 and 3, 4 line-width differences because of anisotropic hyperfine field fluctuation. The Mossbauer spectra indicated that an anisotropic field fluctuation of +H ( $P_{+}$=0.85) was greater than that of -H ($P_{-}$=0.15). We also calculated the field fluctuation frequency factors and the temperature dependence of anisotropy energies from its relaxation rate. We interpreted the effect of Cr ($t^3$$_{2g}$) doping as a decrease in the anisotropy energy.

• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.213-217
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• 1997

We have measured photoluminescence (PL) and time-resolved PL in doped-GaAs. As increasing doping concentration, the PL spectra of n-type GaAs shift to higher energies while the PL spectra of p-type GaAs shift to lower energies than the bandgap of the undoped GaAs. The contribution of the Burstein-Moss effect overrules the band-gap narrowing in n-type GaAs, contrary to p-type GaAs. The PL rise time and decay time become shorter as increasing doping concentration. The PL rise and decay time in doped-GaAs depend on the type of majority carriers and their concentrations, which imply that the carrier-carrier interaction plays an important role in the energy relaxation processes.

• Journal of Fashion Business
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• v.22 no.1
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• pp.71-81
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• 2018

This study aims at exploring how the existing stereotypes of needlework, which has long been regarded as a tribute to domestic labor and hobbies which are the purview of women, have come into play in the current trend of convergence among various fields, techniques and materials. This research examines these trends based on cases in two categories applied to the fields of art and space use products. In the field of art, it can be seen that needlework is applied in a variety of ways in the overall diffusion of craftivism, which is a way of asserting opinions about politics and societies. In yarn bombing and performance art, not only do needlework experts, but also, artists of other genres, underscore their propensity of carrying out projects that take advantage of the basic principles of needlework and various physical properties. Various needlework projects applied to the space use products showed the tendency to interact with the spectator or the user as a basic element through examples of playscape, which has the function of being used for relaxation and play. The study was able to confirm the tendency of interior products, which are made from needlework to furniture and tableware directly, and the tendency of materials' expansion. Based on this research, we are going to explore the possibilities for diverse new fusion attempts in fashion and textiles, as well as art, craft and design fields, in the future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.73-76
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• 2001

We deposited epitaxial $Ba_{0.6}$S $r_{0.4}$Ti $O_3$(BST) films having thickness of 400 nm on MgO(001) substrates, where a 10 nm thick $Ba_{1-x}$S $r_{x}$Ti $O_3$(x=0.1-0.7) interlayer was inserted between BST and MgO to manipulate the stress of the BST films. Since the main difference of those epitaxial BST films was the lattice constant of the interlayers, we were very successful in controlling the stress of the BST films. BST films under small tensile stress showed larger dielectric constant than that without stress as well as those under compressive stress. Stress relaxation was investigated using epitaxial BST films with various thicknesses grown on different interlayers. For BST films grown on $Ba_{0.7}$S $r_{0.3}$Ti $O_3$ interlayers, the critical thickness was about 600 nm. On the other hand, the critical thickness of single-layer BST film was less than 100 nm.00 nm.m.m.m.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.9
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• pp.587-592
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• 2015

In this study, the electrification voltage of electrostatics for silicone rubber sample($4cm{\times}4cm{\times}0.103cm$) following immersion with contaminants of 2 ml, 5 ml, 10 ml for six hours has been measured in through the applied voltage of 10 kV DC at temperature of $80^{\circ}C{\sim}110^{\circ}C$, humidity of 50%~90%. The results of this study are as follows. In case the contaminants is constant, it found that the electrification voltage of electrostatic decreased with increasing temperature and humidity to $35^{\circ}C$, 90%. In case of 2 ml of contaminants concentration, it found that the electrification voltage of electrostatic decreased with increasing temperature and humidity to $35^{\circ}C$, 50%. In case of the sample at temperature of $15^{\circ}C$ and humidity of 50%, it found that the electrification voltage of electrostatic decreased with increasing contaminants to 10 ml.

• Applied Biological Chemistry
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• v.40 no.5
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• pp.427-432
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• 1997

감자전분의 수분함량에 따라 가열하는 동안 전분의 점탄성 성질의 변화를 조사한 결과 전분의 농도가 증가할수록 더 높은 storage modulus (G#)와 loss modulus (G@) 값을 보여주었으며, 호화개시온도 및 호화최대값을 나타내는 온도는 전분농도에 따라 낮은 온도로의 이전을 보여주었다. 20%의 감자전분과 옥수수전분을 비교한 결과, 옥수수전분은 $68^{\circ}C$, 감자전분은 $60^{\circ}C$에서의 호화개시온도를 나타내었으나, G#와 G@값은 옥수수전분이 높게 나타났고 이와 같이 서로 다른 호화개시온도, 호화정도 및 그 최대값을 나타내는 온도변화는 아밀로즈/아밀로팩틴의 함량과 전분 입자의 크기에 따른 것으로 여겨진다. 감자와 옥수수 전분을 각각 3%씩 첨가하여 만든 생선단백질 젤의 파손강도를 측정한 결과 전분들을 첨가한 단백질 젤이 무첨가한 젤보다 더 강하게 나타났으며, 옥수수 전분의 첨가가 감자전분 첨가보다 더 강한 젤의 강도를 나타내었다 혼합비를 달리 첨가하여 만든 겔을 응력완화현상을 측정한 결과 감자 및 옥수수 전분을 첨가한 경우는 초기순간응력, 평형응력 뿐만 아니라 전체적인 응력의 증가현상이 일어났으나 3요소 일반화된 Maxwell 모형으로 분석한 결과는 감자 전분과 옥수수전분에 의한 탄성을 (elastic modulus) 상승효과는 첨가농도의 의존성을 보여 주었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.70-73
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• 2004

The packaging of the integrated circuits requires knowledge of ceramics and metals to accommodate the fabrication of modules that are used to construct subsystems and entire systems from extremely small components. Composite ceramics (Al$_2$O$_3$-SiO$_2$) were tested for substrates. A stress analysis was conducted for a linear work-hardening metal cylinder embedded in an infinite ceramic matrix. The bond between the metal and ceramic was established at high temperature and stresses developed during cooling to room temperature. The calculations showed that the stresses depend on the mismatch in thermal expansion, the elastic properties, and the yield strength and work hardening rate of the metal. Experimental measurements of the surface stresses have also been made on a Cu/Al$_2$O$_3$-SiO$_2$ceramic system, using an indentation technique. A comparison revealed that the calculated stresses were appreciably larger than the measured surface stresses, indicating an important difference between the bulk and surface residual stresses. However, it was also shown that porosity in the metal could plastically expand and permit substantial dilatational relaxation of the residual stresses. Conversely it was noted that pore clusters were capable of initiating ductile rupture, by means of a plastic instability, in the presence of appreciable tri-axiality. The role of ceramics for packaging of microelectronics will continue to be extremely challenging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.308-312
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• 2003

The packaging of the integrated circuits requires knowledge of ceramics and metals to accommodate the fabrication of modules that are used to construct subsystems and entire systems from extremely small components. Composite ceramics ($Al_2O_3-SiO_2$) were tested for substrates. A stress analysis was conducted for a linear work-hardening metal cylinder embedded in an infinite ceramic matrix. The bond between the metal and ceramic was established at high temperature and stresses developed during cooling to room temperature. The calculations showed that the stresses depend on the mismatch in thermal expansion, the elastic properties, and the yield strength and work hardening rate of the metal. Experimental measurements of the surface stresses have also been made on a $Cu/Al_2O_3-SiO_2$ ceramic system, using an indentation technique. A comparison revealed that the calculated stresses were appreciably larger than the measured surface stresses, indicating an important difference between the bulk and surface residual stresses. However, it was also shown that porosity in the metal could plastically expand and permit substantial dilatational relaxation of the residual stresses. Conversely it was noted that pore clusters were capable of initiating ductile rupture, by means of a plastic instability, in the presence of appreciable tri-axiality. The role of ceramics for packaging of microelectronics will continue to be extremely challenging.

• Korean Journal of Optics and Photonics
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• v.9 no.4
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• pp.215-220
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• 1998

We proposed an in situ measurement set-up and technique to measure the various electro-optic(E-O) properties of the E-O polymer. Using the proposed measurement set-up, the electro-optic effect and birefringence of unpoled side-chain E-O polymer induced by the strong dc and ac electric field were observed. The dependence of the E-O coefficients on the various poling conditions were measured with real time. To evaluate the thermal stability of the poled polymer the relaxation of the E-O effect was measured and the result was compared with well known polymer materials. The proposed measurement reduces the number of experimental steps and saves measurement time.

• Korea-Australia Rheology Journal
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• v.17 no.4
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• pp.165-170
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• 2005

In this study, high intensity ultrasound was employed to induce mechano-chemical degradation during melt mixing of polycarbonate (PC) and a series of styrene-acrylonitrile (SAN) copolymers. It was confirmed that generation of macroradicals of constituent polymers can lead to in-situ copolymer formation by their mutual combination, which should be an efficient path to compatibilize immiscible polymer blends and stabilize their phase morphology in the absence of other chemical agents. Based on the effectiveness of the compatibilization by ultrasound assisted mixing process, we investigated the effects of viscosity ratio of PC and SAN and AN content in SAN on the compatibilization of PC/SAN blends. It was found that effectiveness of compatibilization is optimal when the AN content is in the range of favorable interaction with PC and the viscosity of the matrix is higher than that of the dispersed phase. In addition, changes in the interfacial tension between PC and SAN were assessed by examining relaxation spectra which were obtained from measuring rheological properties of ultrasonically treated blends.