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51.
Jung‐Min Moon Bong‐Soo Kim Hyun‐Jong Paik Jang‐Oo Lee Emiko Mouri Kohji Yoshinaga 《Polymer Engineering and Science》2010,50(6):1067-1074
Silica nanoparticles with well‐defined, highly grafted dense poly(methyl methacrylate) (MMA) were prepared by surface‐initiated activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) of methyl methacrylate with an initiator‐fixed silica particle in the presence of air. Two different polymerizations of MMA were carried out under the same conditions using tris[2‐(dimethylamino)ethyl]amine (Me6TREN) and N,N,N′,N′,N″‐pentamethyldiethylene‐triamine (PMDETA) as the ligand, respectively. In the CuCl2/PMDETA system, polymerization appeared to be more controlled with a lower polydisperisty compared with the CuCl2/Me6TREN system. The monolayer of these particles was formed at the air–water interface using Langmuir‐Blodgett (LB) technique. Multilayers of the particles were fabricated by repetition of LB depositing. A surface pressure–area (π–A) measurement and SEM observation were used to characterize the particle arrays. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers 相似文献
52.
Jong Hoo Paik Sahn Nahm Young Sik Kim Hyun Min Park Hwack Joo Lee Jae Dong Byun 《Journal of Materials Science》2003,38(3):621-628
The crystal structure of (Ba1–x
La
x
)[Mg(1 + x)/3Nb(2–x)/3]O3 (BLMN) ceramics with 0 x 1 was investigated using X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). When the La content, x, was above 0.1, the 1:2 ordered hexagonal structure found in Ba(Mg1/3Nb2/3)O3 (BMN) was transformed into the 1:1 ordered cubic structure. The 1:1 ordered cubic structure was maintained up to x = 0.7. When x exceeded 0.7, however, BLMN exhibited a 1:1 ordered monoclinic structure, rather than a 1:1 ordered cubic structure. La(Mg2/3Nb1/3)O3 (LMN) has a 1:1 ordered monoclinic P21/n structure with a = 5.6004 Å, b = 5.6414 Å, c = 7.9346 Å, and = 89.9819°. The monoclinic LMN has the in-phase and the anti-phase tilt of oxygen octahedra. The anti-parallel shift of A-site cations was also found in LMN. 相似文献
53.
AbstractThis study examines how R&D intensity and open innovation affect the technological capabilities of firms in newly-developed countries, such as South Korea. East Asian latecomers are transitioning from a catch-up phase toward becoming leaders, and they are engaging in open innovation activities to drive this transition. This research quantitatively analyzes three kinds of open innovation activities—outside-in, inside-out, and coupled—to investigate their influence upon technological capabilities, while also considering the effect of R&D intensity. Data from 75 South Korean medium-sized firms were analyzed, and two major findings are reported. First, technological capabilities are enhanced by some open innovation activities and by R&D intensity. Second, R&D intensity negatively moderates the impact of open innovation activities on technological capabilities. Therefore, it may be concluded that firms with relatively low R&D intensity will gain the most benefit from increasing their open innovation activities. 相似文献
54.
Synthesis of BaCu(B2 O5 ) Ceramics and their Effect on the Sintering Temperature and Microwave Dielectric Properties of Ba(Zn1/3 Nb2/3 )O3 Ceramics 总被引:1,自引:0,他引:1
Min-Han Kim Jong-Bong Lim Jae-Chul Kim Sahn Nahm Jong-Hoo Paik Jong-Hee Kim Kyeong-Soon Park 《Journal of the American Ceramic Society》2006,89(10):3124-3128
BaCu(B2 O5 ) ceramics were synthesized and their microwave dielectric properties were investigated. BaCu(B2 O5 ) phase was formed at 700°C and melted above 850°C. The BaCu(B2 O5 ) ceramic sintered at 810°C had a dielectric constant (ɛr ) of 7.4, a quality factor ( Q × f ) of 50 000 GHz and a temperature coefficient of resonance frequency (τf ) of −32 ppm/°C. As the BaCu(B2 O5 ) ceramic had a low melting temperature and good microwave dielectric properties, it can be used as a low-temperature sintering aid for microwave dielectric materials for low temperature co-fired ceramic application. When BaCu(B2 O5 ) was added to the Ba(Zn1/3 Nb2/3 )O3 (BZN) ceramic, BZN ceramics were well sintered even at 850°C. BaCu(B2 O5 ) existed as a liquid phase during the sintering and assisted the densification of the BZN ceramic. Good microwave dielectric properties of Q × f =16 000 GHz, ɛr =35, and τf =22.1 ppm/°C were obtained for the BZN+6.0 mol% BaCu(B2 O5 ) ceramic sintered at 875°C for 2 h. 相似文献
55.
The high molecular weight (MW) polypropylene with average particle size of 60 nm was synthesized by controlled growth mechanism using Ziegler–Natta catalyst. The atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies showed that PP nanoparticles were spherical in shape. Structure and crystallinity were concomitantly studied through Fourier transform infrared spectroscopy and X‐ray diffraction, respectively. It shows nanospherical PP particles with more crystallinity (~ 75%) compared with macrosized PP (~ 59%). In addition, differential scanning calorimetry studies revealed the finite particle size effect on Tg and the scale dependence Tg followed a first order exponential trend. As particle size goes down to nano‐ scale from macrosize, continuous elevation of Tg's were observed from ?25 to ?11°C. This phenomenon was directed to configuration entropy of single spherical nanoparticles of PP. The mechanical properties and surface roughness were also evaluated through AFM. At last, the properties of nanosized PP were compared with micron and macrosized particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
56.
Seasoned beef called Jangzorim in Korea is produced by boiling in soy sauce, and is a popular food in Korea. The aim of this study is to evaluate the microbial safety and physical qualities of sous vide processed seasoned beef, and the effect of nisin during storage. Sous vide processed packages with or without nisin (100 IU or 500 IU) were stored at 4 °C or 25 °C for 60 days, and samples measured for quality at regular intervals throughout this storage period. In the case of 25 °C storage, the number of mesophilic microorganisms in seasoned beef packages without nisin increased markedly, but with nisin there was no observed increase. Psychrotrophic microorganisms, anaerobic microorganisms, and B. cereus cells showed similar trends, although C. perfringens was not detected in all samples. At 25 °C storage, changes in the cutting force of packages containing nisin showed no significant change, packages without nisin decreased markedly. The colour of packages without nisin showed a drastic decrease in lightness (‘L’) while no changes were observed in packages with nisin. 相似文献
57.
Jeom Kee Paik 《钢结构》2008,(4)
众所周知,与其他因素相比焊接引起的初始挠曲会极大地影响被焊板的极限强度,这意味着在计算板的极限强度以前判别板的初始挠曲性状是极其重要的。本文旨在研究海洋工程中应用的铝板在焊接过程中产生的初始挠曲特性。研究中共有78个单跨和多跨加劲平板铝结构,其与80m长全铝制高速船的基础结构同尺寸,采用金属惰性气体焊接。然后计算出加劲肋之间的初始挠曲。通过对数据库进行统计分析,得到初始挠曲变化系数。研究结果有助于焊接铝板结构的可靠性分析、极限强度确定和制作工艺控制。 相似文献
58.
Jae?H.?KimEmail author Jung?M.?Lee Ho?C.?Shin Young?H.?Paik 《Metals and Materials International》2003,9(6):593-597
It is known that oxide inclusions in liquid metal carry mostly positive charges on their surfaces. In an electrostatic field,
therefore, such charged particles suspended in a liquid metal experience forces and accumulate in the region of the negatively
charged surface, resulting in the separation of oxide inclusions from the liquid metal. In this study, this principle was
experimentally demonstrated for the case of a capacitor cell by the imposition of a d.c. potential on electrodes. The capacitor
cell consisted of a dielectric container of Pyrex tube, a high voltage d.c. source, and two electrodes, which were symmetrically
attached onto the outer surface of the Pyrex. tube. Experiments were carried out for suspensions of liquid tin/metal oxides,
such as SnO2, WO3, and PbO under an applied potential of up to 12 kV. All experimental results were in good agreement with the theoretical
prediction and showed that the degree of separation was significantly increased with the applied potential. 相似文献
59.
Backseolgi is a Korean traditional rice cake, which is prepared by steaming the rice flour. After cook-chilling processing, backseolgi samples packaged by a modified atmosphere package (MAP), top sealing package (TSP), and linear low density-polyethylene package
(LDPA; control) were evaluated in regard to microbial safety and sensory characteristics during storage. During storage at
30°C, the cell numbers of aerobic, psychrophilic, and anaerobic bacteria for the MAP sample increased to below 2 log CFU/g
for 10 days, whereas the control and TSP samples increased more than 5.0 log CFU/g after 4 days. After 50 days of storage
at 3°C, the cell numbers in the MAP sample were below 1.0 log CFU/g, whereas they were approximately 3.0 log CFU/g in the
control and TSP samples. In the case of the sensory evaluation, the MAP sample score was above 5.0, whereas the scores of
the CON and TSP samples were 1.0. As a result, MAP was identified as the most effective packaging method for increasing microbial
safety while maintaining the sensory characteristics of the cook-chilled backseolgi. 相似文献
60.
Kyung-Woon Jang Kyung-Wook Paik 《Electronics Packaging Manufacturing, IEEE Transactions on》2009,32(2):74-80
In this paper, the effects of anisotropic conductive film (ACF) viscosity on ACF fillet formation and, ultimately, on the pressure cooker test (PCT) reliability of ACF flip chip assemblies were investigated. The ACF viscosity was controlled by varying the molecular weight of the epoxy materials. It was found that the ACF viscosity increased as the increase of molecular weight of the epoxy materials. However, there was little variation of the thermomechanical properties among the evaluated ACFs with different viscosites. Also, the results showed that the ACFs have no differences in moisture absorption rate, die adhesion strength, and degree-of-cure. In scanning electron microscopy images, the lower ACF viscosity resulted in the smoother ACF fillet shape and the higher fillet height. From the results of PCT, the ACF flip chip assembly with the smoother fillet shape showed better reliability in terms of contact resistance changes. After 130 h of PCT, the flip chip assembly with lower ACF viscosity also showed a lesser degree of delamination at the ACF/chip interface. 相似文献