• Transactions on Electrical and Electronic Materials
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• v.17 no.5
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• pp.257-260
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• 2016

In this paper, two configurations (T-type and Y-type) of dual band Wilkinson Power Divider based upon Hilbert curves are presented. Formerly, the concept of Hilbert Curves was implemented in only designing microstrip antennas. In power dividers, this is the very first attempt of incorporating them for size reduction. In addition to this, an effect of inculcation of high-dielectric constant layer (Hafnium-oxide, HfO₂, ε_r= 25) between a substrate and top metallization in both configurations was investigated. The proposed configurations are designed on a high resistive silicon substrate (HRS) for L and S bands with resonating frequencies of 1.575 and 3.4 GHz. Both configurations have return loss that is better than 20 dB and an insertion loss of around 6 dB; isolation better than 30 dB was achieved for both models.

• The KIPS Transactions:PartB
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• v.17B no.2
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• pp.177-182
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• 2010

This paper proposes a new document clustering method using PCA and fuzzy association. The proposed method can represent an inherent structure of document clusters better since it select the cluster label and terms of representing cluster by semantic features based on PCA. Also it can improve the quality of document clustering because the clustered documents by using fuzzy association values distinguish well dissimilar documents in clusters. The experimental results demonstrate that the proposed method achieves better performance than other document clustering methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6B
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• pp.1068-1073
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• 2000

In this paper, we propose a serially concatenated turbo bode/turbo equalizer scheme for optical storage systems. Without modulation coding, a random data sequence is directly passed through the optical channel. In simulation, the channel includes jitter of 15% and AWGN. The densities of the channel are S=4.6 and S=7.0. The code rates of turbo code are 4/5, 8/9 and 16/17. All code rates, the bit error probability is less than 10-5 at 24dB when we and jitter of 15%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.47-54
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• 2018

These days, the aerospace industry uses larger machining parts and assembly parts than those in the past. The assembly machines also show the same trend. This study is concerned with the alignment measuring apparatus for the B-axis of a separated multi-axis machine. The alignment measuring apparatus is widely installed for assembly machines in the aircraft assembly process. The alignment measuring apparatus consists of a swivel part and a measuring part. This is a new conceptual idea under patent. All elements of the alignment measuring apparatus are analyzed with the FEM. The analyzed result shows that the alignment measuring apparatus is high in accuracy with stability and steady deformation.

• Korean Journal of Crystallography
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• v.11 no.2
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• pp.84-88
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• 2000

The crystal of cholesteryl crotylcarbonate was investigated by X-ray diffraction method. Crystallographic data for the title compound: P21, a=13.510(2)Å, b=11.843(2)Å, c=19.882(2)Å, β=106.88(1)°, Z=4. Reflections were collected with an Enraf-Nonius CAD-4 diffractometer equipped with a graphite monochromator. The structure was solved by direct methods and refined by least-squares analyses. The final R value was 0.125 for 2607 reflections. The cholesterol fragment of the title compound were in good agreement with those for related cholesterol derivatives. The molecules were stacked in clearly separated layers. At the center of the layers, there were cholesteryl-cholesteryl interactions between the symmetry-related B molecules and the cholesteryl-C(17) side chain of A molecules. There were also interactions between the C(17) side chain of B molecules and the crotylcarbonate chain in the interface region between layers. The crystal structure of the title compound turned out to be isostructural with those of cholesteryl ethylcarbonate and cholesteryl propylcarbonate.

• Journal of Life Science
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• v.17 no.6 s.86
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• pp.873-875
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• 2007

Effects of hot-water extract from Sasa quelpaertensis leaf (HWES) on melanogenesis were investigated in B16/F10 mouse melanoma cells. HWES inhibited cellular tyrosinase activity and melanin biosynthesis in a dose-dependent manner. Western blotting analysis showed that HWES dose-dependently inhibited tyrosinase and tyrosinase related protein-1 expression. Also, HWES suppressed sustained ERK activation in a concentration-dependent manner, suggesting that HWES inhibits the melanin biosynthesis through the suppressive effect against pathway involving sustained ERK activation.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.7-12
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• 2016

This paper proposes a metal contact RF MEMS switch which utilizes a see-saw mechanism to acquire a switching action. The switch was built on a quartz substrate and involves vertical deflection of the beam under an applied actuation voltage of 5.46 volts over a signal line. The see-saw mechanism relieves much of the operation voltage required to actuate the switch. The switch has a stiff beam eliminating any stray mechanical forces. The switch has an excellent isolation of −90.9 dB (compared to − 58 dB in conventional designs ), the insertion of −0.2 dB, and a wide bandwidth of 88 GHz (compared to 40 GHz in conventional design ) making the switch suitable for wide band applications.

• The Pure and Applied Mathematics
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• v.17 no.1
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• pp.65-80
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• 2010

In [17, 18], the fuzzy stability problems for the Cauchy additive functional equation and the Jensen additive functional equation in fuzzy Banach spaces have been investigated. In this paper, we prove the generalized Hyers-Ulam stability of the following quadratic functional equations in fuzzy Banach spaces: (0.1) f(x + y) + f(x - y) = 2f(x) + 2f(y), (0.2) f(ax + by) + f(ax - by) = $2a^2 f(x)\;+\;2b^2f(y)$ for nonzero real numbers a, b with $a\;{\neq}\;{\pm}1$.

• Bulletin of the Korean Chemical Society
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• v.17 no.5
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• pp.447-452
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• 1996

Three conformational isomers of calix[4]arene butanoate were isolated from the reaction of calix[4]arene and butanoyl chloride in the presence of NaH and their structures were determined by NMR spectra as 1,2-alternate 2a, partial cone 2b and 1,3-alternate conformer 2c, respectively. The crystal structure of 2a has been determined by X-ray diffraction method. The crystals are monoclinic, space group C2/c, a=18.435 (4), b=13.774 (2), c=16.941 (3) Å, β=116.23 (1)°, Z=4, V=3858.8 (12)Å3, Dc=1.21 g cm-3, Dm=1.21 g cm-3. The molecule is in the 1,2-alternate conformation. It has two-fold symmetry axis along the line connecting between C (7AA') and C (7BB') parallel to the b axis of crystal lattice.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.483-487
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• 1991

The tetraaza macrocyclic ligand 3,14-dimethyl-2,6,13,17-tetraazatricyclo $[14,4,0^{1.18} ,0^{7.12}]$docosa-2,12-diene(B), that contains two cyclohexane rings, has been prepared as its dihydroperchlorate salt by the nontemplate condensation of methyl vinyl ketone with 1,2-diaminocyclohexane and perchloric acid. Reduction of B with sodium borohydride produces 3,14-dimethyl-2,6,13,17-tetraazatricyclo$[14,4,0^{1.18},0^{7.12}]$docosane(C). Square planar Ni(Ⅱ) and Cu(Ⅱ) complexes of B and C have been prepared by the reaction of the metal ions and the ligands. Synthesis, characterization, and the properties of the ligands and their metal complexes are reported.