• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2002.02a
• /
• pp.3-4
• /
• 2002

The stainless steel sheathed MgB$_2$ tapes with Cu addition were fabricated by PIT method without heat treatment. The $J_{c}$ value of 5,600 A/ $cm^{2}$and 16,000 A/$cm^{2}$ at 4.2 K and 5 T were obtained for the $MgB_{2}$ tape and 10 vol % of Cu added $MgB_{2}$ tape respectively. The $J_{c}$-B curve shows enhancement in J$_{c}$ under magnetic field, which suggests enhancement in flux pinning property with Cu addition.n.

• Journal of Radiation Industry
• /
• v.5 no.3
• /
• pp.191-196
• /
• 2011

The economic scale of nuclear application is a good indicator to show how the radiation technology is useful and contribute to improve public welfare and living standard. Recent research in Japan shows that the economic scale of nuclear field was 4,112 B¥ for radiation application(46%) and 4,741 B¥ for nuclear energy (54%) playing a role of "two wheels of one cart" in nuclear field and the total 8,853 B¥ constitutes 1.8% of gross domestic products (GDP). The radiation application consisted of 2,295 B¥ (56%) in industry (semiconductor, sterilization, nondestructive testing, radiation processing of tires, etc.), 1,538 B¥ (37%) in medicine (therapy and diagnosis such as X-ray, nuclear medicine, computed tomography, etc.) and 279 B¥ (7%) in agriculture (mutation breeding, food irradiation, sterile insect technique, etc.). Radiation application by ${\gamma}$-ray, electron beam and ion beam is steadily increasing in Japan.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.849-851
• /
• 2000

The value of $I_c$(critical current) in HTS (High Temperature Superconductor) tape has a great influence on $B{\bot}$ (vertical field). Therefore, in shape design of field coil for the HTSG(High Temperature Superconducting Generator), a method to reduce the $B{\bot}$ should be considered in order to maintain the stability and substantial improvement on the performance. On the basis of the magnetic field analysis, this paper deals with various field coil shape to obtain small $B{\bot}$ by using Biot-Savart's law and image method. Moreover the analysis is verified by comparison with experimental results. And also this paper presents the advanced model by using 3D FEM(3 Dimensional Finite Element Method), in which flux density at armature is calculated in 5kVA class HTSG.

• Journal of the Korean Magnetics Society
• /
• v.21 no.1
• /
• pp.10-14
• /
• 2011

We have measured the ferromagnetic resonance (FMR) signal in as deposited and $400^{\circ}C$ annealed CoFeB/MgO thin film to investigate the annealing effect on magnetic anisotropies and FMR linewidth (${\Delta}H_{PP}$). The uniaxial anisotropy field ($H_{K1}$) was only observed in the as deposited sample. Whereas, in the $400^{\circ}C$ annealed sample, the biaxial anisotropy field ($H_{K2}$) was additionally observed in accompany with uniaxial anisotropy field ($H_{K1}$). The appearance of biaxial anisotropy fields was originated from the crystalline growth of bcc CoFeB(001) from the MgO(001) interface and by the B diffusion during thermal annealing. Also, the ${\Delta}H_{PP}$ of $400^{\circ}C$ annealed sample was increased compared with that of as deposited sample, which was due to the broad distribution of the magnetization axis by the biaxial anisotropy.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.1
• /
• pp.91-96
• /
• 2008

In this paper, a monopulse fled for three mode $2{\times}2$ array feed horn antenna was designed. Gain of single feed was 8.25dB. Increasing property of gain and rectangular waveguide and reflection of free space is decreased because it has structure extending to electric plane at connected part from transformation to free space. When fled port1 and port2 is placed vertically and thickness of aperture hem is reduced, isolation is satisfied with property of lower -25dB. Also, at higher frequency, it is confirmed that isolation is improved. Combination of electric field occurs less influence because port1 and port3 is placed horizontally and distribution of electric field is connected to parallel. However, because of combination of electric field, it is more improved from 2dB to 6dB than isolation of port1 and port2. Direct combination occult less effect at port1 and port4 than effect of port2 and port3, it is lower -35dB.

• Journal of the Korean Magnetics Society
• /
• v.23 no.5
• /
• pp.154-158
• /
• 2013

We have analyzed the magnetization curves measures by using VSM and MOKE in synthetic antiferromagnetic coupled CoB/Ru/CoB thin film. The measured results were compared with calculated ones by Stoner-Wohlfarth model based on the magnetization behavior of two ferromagnetic layers ($M_1$, $M_2$). The calculated total magnetization ($M_{tot}=M_1+M_2$) and single layer magnetization($M_1$) behaviors were compared with measured results by using VSM and MOKE, respectively. The total magnetization curve ($M_{tot}=M_1+M_2$) showed reversible magnetization behavior with flopping field of about 50 Oe. While single layer magnetization ($M_1$) behaviors showed irreversible magnetization behavior in the field range of $H_F$ < H < $H_F$. These magnetization behaviors were explained by the angle difference between magnetization directions of two ferromagnetic layers in SAF sample.

• Journal of the Korean Ceramic Society
• /
• v.40 no.10
• /
• pp.925-930
• /
• 2003

The dielectric polarizability-related factors contributing to the $\tau$$_{\varepsilon}$ have been analysed in terms of dielectric permittivity $\varepsilon$, Tolerance Factor (TF), and octahedron tilt angles in (1-x)CaTi $O_3$-x[A(B', B″) $O_3$] (A=Ca, La, Li, B'=Al, Fe, Mg, B″=Nb, Ta) and (S $r_{0.2}$C $a_{0.8}$)( $Ti_{1-x}$ Z $r_{x}$) $O_3$. All the compounds have the orthorhombic Pbnm structure except the end members A(B', B″) $O_3$ and the solid solutions of x$\geq$0.8. The additional dipole field effect is suggested as a dominant factor contributing to $\tau$$_{\varepsilon}$ in CaTi $O_3$-based ceramics having relatively large $\varepsilon$, which has not been generally considered in the previous reports dealing with the $\tau$$_{\varepsilon}$. This study has been focussed on delineating the dipole field effect on the $\tau$$_{\varepsilon}$ in comparison to the octahedron tilt effect in CaTi $O_3$-based ceramics.cs..cs.

• Journal of Ecology and Environment
• /
• v.29 no.3
• /
• pp.237-245
• /
• 2006

Changes of the biomass, net primary productivity and P/B ratio during abandoned field succession after shifting cultivation were investigated in Pyoungchang, Gangwon-Do, Korea. Aboveground standing biomass of herb species showed the maximum value (3.8 ton/ha) in the 5 year old-field, and decreased thereafter. Litter dry weight was depicted as a parabola form showing the gradual increment during the first 50 years and slight decrease thereafter. Basal area tended to increase logarithmically during abandoned field succession. Tree density showed the gradual increment during the first 15 years and decreased thereafter by the self-thinning process. In the later successional stage (80 years old-field), the shoot density distribution of the tree species by DBH class showed the reverse J shaped curve and Quercus mongolica dominated. Total standing biomass increased slowly in the earlier successional stages and later successional stages, and increased rapidly during the mid-successional stages ($10{\sim}50$ years old-field). Total standing biomass in the 5, 10, 20, 50 and 80 years old-fields were estimated 5, 14, 75, 251 and 373 ton/ha, respectively. Annual net primary productivity were depicted as a parabola form showing the gradual increment during the first 35 years and declined thereafter. The increment rates of the annual net primary productivity in the earlier successional stages showed the higher value than mid-successional stages. The annual net primary productivities in the 5, 10, 20, 35, 50 and 80 years old-field were estimated 8.6, 9.3, 12.9, 15.1, 13.7 and 3.6 ton/ha/yr, respectively. The estimated P/B ratio tended to decrease exponentially during abandoned field succession. The estimated P/B ratio in the 5, 10, 20, 50 and 80 years old-field were 0.60, 0.39, 0.19, 0.06 and 0.01, respectively. These results were fairly in accordance with the bioenergetics model during the forest succession projected by Odum(1969).

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.9
• /
• pp.6-12
• /
• 2011

In this paper, we propose a design method for a reliable and improved field-installable optical connectors(FIOC) which are needed for long-distance and low loss FTTH configuration. To this end, we optimize the angle of splicing between the inner fiber and the field fiber of the FIOC, so that the low loss connection of optical fibers is possible without using any angle alignment tools as well as angled cleavers. More precisely, we set the cutting angle of the inner filber and the field fiber to be $2^{\circ}$ by using an angled cleaver and $0^{\circ}{\sim}1^{\circ}$ by using a general fiber cutter, respectively. Splicing these two optical fibers without any further adjustment, we can keep the insertion loss within 0.3dB and the reflection loss within -60dB.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.1C
• /
• pp.131-139
• /
• 2008

This paper presents a scalable dual-field Montgomery multiplier based on a new multi-precision carry save adder(MP-CSA), which operates in both types of finite fields GF(p) and GF($2^m$). The new MP-CSA consists of two carry save adders(CSA). Each CSA is composed of n = [w/b] carry propagation adders(CPA) for a modular multiplication with w-bit words, where b is the number of dual field adders(DFA) in a CPA. The proposed Montgomery multiplier has roughly the same timing complexity compared with the previous result, however, it has the advantage of reduced chip area requirements. In addition, the proposed circuit produces the exact modular multiplication result at the end of operation unlike the previous architecture. Furthermore, the proposed Montgomery multiplier has a high scalability in terms of w and m. Therefore, it can be used to multiplier over GF(p) and GF($2^m$) for cryptographic applications.