• Journal of the Chungcheong Mathematical Society
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• v.21 no.3
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• pp.339-345
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• 2008

We prove the existence of the positive solution for the nonlinear system of suspension bridge equations with Dirichlet boundary condition and periodic condition $$\{u_{tt}+u_{xxxx}+av^+=1+{\epsilon}_1h_1(x,t)\text{ in }(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,\\v_{tt}+v_{xxxx}+bu^+=1+{\epsilon}_2h_2(x,t)\text{ in }(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,$$ where $u^+={\max}\{u,0\},\;{\epsilon}_1,\;{\epsilon}_2$ are small numbers and $h_1(x,t)$, $h_2(x,t)$ are bounded, ${\pi}$-periodic in t and even in x and t and ${\parallel}h_1{\parallel}={\parallel}h_2{\parallel}=1$.

• Korean Journal of Mathematics
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• v.16 no.1
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• pp.41-49
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• 2008

We show the existence of a negative solution for the system of the following nonlinear wave equations with critical growth, under Dirichlet boundary condition and periodic condition $$u_{tt}-u_{xx}=au+b{\upsilon}+\frac{2{\alpha}}{{\alpha}+{\beta}}u_+^{\alpha-1}{\upsilon}_+^{\beta}+s{\phi}_{00}+f,\\{\upsilon}_{tt}-{\upsilon}_{xx}=cu+d{\upsilon}+\frac{2{\alpha}}{{\alpha}+{\beta}}u_+^{\alpha}{\upsilon}_+^{{\beta}-1}+t{\phi}_{00}+g,$$ where ${\alpha},{\beta}>1$ are real constants, $u_+={\max}\{u,0\},\;s,\;t{\in}R,\;{\phi}_{00}$ is the eigenfunction corresponding to the positive eigenvalue ${\lambda}_{00}$ of the wave operator and f, g are ${\pi}$-periodic, even in x and t and bounded functions.

• Korean Journal of Mathematics
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• v.16 no.3
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• pp.355-362
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• 2008

We prove the existence of a unique positive solution for a class of systems of the following nonlinear suspension bridge equation with Dirichlet boundary conditions and periodic conditions $$\{{u_{tt}+u_{xxxx}+\frac{1}{4}u_{ttxx}+av^+={\phi}_{00}+{\epsilon}_1h_1(x,t)\;\;in\;(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,\\{v_{tt}+v_{xxxx}+\frac{1}{4}u_{ttxx}+bu^+={\phi}_{00}+{\epsilon}_2h_2(x,t)\;\;in\;(-\frac{\pi}{2},\frac{\pi}{2}){\times}R,$$ where $u^+={\max}\{u,0\},\;{\epsilon}_1,\;{\epsilon}_2$ are small number and $h_1(x,t)$, $h_2(x,t)$ are bounded, ${\pi}$-periodic in t and even in x and t and ${\parallel} h_1{\parallel}={\parallel} h_2{\parallel}=1$. We first show that the system has a positive solution, and then prove the uniqueness by the contraction mapping principle on a Banach space

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.914-923
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• 2009

Helix antennas have been widely applied to satellite TT&C, data communication and GPS receiver systems onboard military, remote sensing and communication purpose satellites. The helix antennas are known to be convenient to control impedance and radiation coverage characteristics with a maximum directivity in satellite z-axis. Waveguide horn is commonly used for radar system that needs ultra-wideband pulse for exploration ground radar and electromagnetic disability measurement etc. It has high efficiency and low reflection characteristics provided by the low-profile shape and suppressed radiation distortion. In this paper, a waveguide horn structure incorporated with helix antenna design is proposed for satellite applications that require ultra-wideband pulse radar and high rate RF data communication link to ground station over wide coverage area. The main design concern is to synthesize variable beam forming pattern based on modified horn-helix combination helicone structure such that multi-mission antenna is implemented applicable for TT&C, earth observation, high data rate transmission. Waveguide horn helps to reduce the overall antenna structure size by introduction fold type reflector connected to the tapered helix antenna. The next generation KOMPSAT satellite currently under development requires high-performance precision attitude control system. We present an initial design of a hybrid hern-helix antenna structure suitable for efficient RF communication module design of multi-purpose satellite systems.

• Electric Engineers Magazine
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• v.228 no.8
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• pp.52-57
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• 2001

Presently the Korean grounding system uses TN system, multi-grounding method with IT independent grounding method. Nevertheless TN system can't exist with TT system in the technological terms. If they coexist, it causes ground-fault circuit not to operate, and brings about different electrical potential rise by customer system. It brings about serious problems for safety. This paper aims for improving method of grounding system based on the technical analysis on instances in foreign countries and Korea. Almost standards and construction manner were apt to be internationalized after WTO/TBT agreement was concluded. The internal grounding systems should meet the international criteria and reliability for safety, and be provided with technologically impeccable standards.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.343-346
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• 2009

The grounding system of low voltage power systems is TT grounding system in Korea. In order to follow the international standard, TN grounding system is adopted. However, the performance of grounding systems has not been evaluated. This paper deals with the experimental results of protection ability of grounding system when lightning surge invades to the neutral line of low voltage power system. As a result, the TT grounding system is most frail for the lightning surge and it does not protect the electrical devices. On the other hand, the TN grounding system perfectly protects the electrical equipment and prevents the electric shock for human through the equipotential bonding. In case of TN system with supplement grounding, it is very important to lower the supplement grounding resistance to protect the electrical equipment and electric shock for human.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.467-470
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• 2004

In early 2004, KARI developed 5ft S-Band TT&C antenna for especially KOMPSAT-2 operation in LEOP phase. This paper shows system features of 5ft S-Band antenna and its test result with KOMPSAT-l. Tracking test, command uplink test and telemetry downlink test were performed. Through tests, 5ft antenna was verified to be operational in uplink and downlink with KOMPSAT series. Due to its inherent wide 3dB beam-width of about 7deg at S-Band, this antenna system can be used very effectively even though orbital information is less accurate like LEOP and spacecraft safe mode.

• Journal of the Korean Society of Radiology
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• v.10 no.8
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• pp.603-610
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• 2016

This study was performed to analyze the results of radiologic parameters compared both leg weight bearing position to single leg weight bearing position in ankle osteoarthritis. Between January 2016 and June 2016, 25 patients (50 ankles) who visited our Hospital to treat ankle pain. In radiographic assessment, We masured tibial anterior surface angle(TAS), tibial medial malleolar angle(TMM), talar tilting angle(TT), joint space width(JSW), tibiotalar joint space, fibulotalar joint space of ankle as radiologic parameters. On the right leg of the both leg weight bearing position, TAS was $87.24^{\circ}$, TT was $6.44^{\circ}$, TMM was $26.76^{\circ}$, fibulotalar joint space was 0.98mm. Right leg of the single leg weight bearing position, TAS was $88.93^{\circ}$, TT was $2.41^{\circ}$, TMM was $19.77^{\circ}$, fibulotalar joint space was 1.6mm. And then, on the left leg of the both leg weight bearing position, TAS was $87.25^{\circ}$, TT was $5.71^{\circ}$, TMM was $23.92^{\circ}$, fibulotalar joint space was 1.22 mm and left leg of the single weight bearing position, TAS was 88.75, TT was $3.19^{\circ}$, TMM $21.45^{\circ}$, fibulotalar joint space was 1.22 mm. There are unsimilarity between measure values of TAS and tibiotalar joint space. As the result of test of weight bearing ankle study, it would be more exact to examine to measure one side in the first time rather than both to conclude on accurate measurement.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.1
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• pp.1-6
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• 2007

Leptin is the hormone product of the obese gene and is synthesized and secreted predominantly by white adipocytes and relates to the feedback system that regulates long-term body fat weight and composition. Therefore, the leptin gene could be an excellent candidate gene controlling fat deposition, carcass traits and meat quality in beef cattle. The objective of this study was to evaluate the association of 3 SNPs (A1127T and C1180T in exon 2 and C3100T in exon 3) in the bovine leptin gene with carcass and meat quality traits in Korean cattle. The C1180T SNP was associated with backfat thickness (BF) and marbling score (MS) (p<0.05). Animals with the genotype CC had higher BF than animals with TT genotype and higher MS compared with CT and TT genotypes. No significant associations were observed between the C3100T SNP and any carcass and meat quality traits analyzed. The effect of the A1127T SNP was not analyzed because the TT genotype was not detected and the AT genotype showed only 1.0% frequency. These results suggest that the C1180T SNP of the leptin gene may be useful as a genetic marker for carcass and meat quality traits in Korean cattle.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.5
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• pp.36-41
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• 2009

In this paper an Investigation into the actual condition of electrical equipment installation for the inspection method development based on IEC 60364. The analysis objects are the difference between electrical equipments installation in korea & electrical equipments installation based on the IEC 60364. The measurement elements are loop impedance, operating characteristic of circuit breaker and protective conductor continuance. As a result, the korea electrical equipments installation was almost same the TT system but some different of protective conductor continuance. Electrical equipments installed TN-C-S has noting problem about installation but manager dose not understand about IEC 60364.