• Publications of The Korean Astronomical Society
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• v.22 no.1
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• pp.1-20
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• 2007

Quasars at cosmological distances can be gravitationally lensed by galaxies into two or more images. The probability of this lensing and the angular separation between the images depend on the geometry and the expansion history of the universe as well as the lensing galaxies. The time delay between lensed images is also a direct indicator of the size of the universe. I review these cosmological applications of multiple-image gravitationally lensed quasars to determine or constrain the cosmological parameters.

• Journal of the Korea Society for Simulation
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• v.10 no.1
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• pp.73-82
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• 2001

The main idea behind the Intelligent Networks (IN) concept is the separation of switching functionality from the service control, in order to meet various service requirements of subscribers and development of new services in time. On the increase of subscriber and for high quality of service, the IN upgrades its service systems, and there are a number of ways depending on the system architecture and the characteristics of services. This paper compares two alternatives, traces the performance of them by means of the simulation technique, and finally puts a rule to select one of them.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.203-208
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• 1987

Design problem of output feedback controllers for discrete large scale systems using simplified model is investigated. It is shown that neglecting fast modes does not generally guarantee the stability of the closed loop system. In this paper, the design procedure is proposed to stabilize the system by minimizing a quadratic cost function for the simplified model and a measure of stability for the neglected fast model.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.125-128
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• 1999

A systematic study of the aleocharine tribe Falagriini in Korea is presented. Three species are recognized, all of which are recorded for the first time in Korea [Falagria sulcata (Paykull), Myrmecopora (Lamproxenusa) rufescens (Sharp), and Myrmecocephalus sapida (Sharp)］. A key is provided for separation of the known species of the Falagriini and photo-graphs of habitus are presented.

• YAKHAK HOEJI
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• v.54 no.3
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• pp.164-167
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• 2010

Column chromatographic separation of the MeOH extract from the aerial parts of Hibiscus manihot led to the isolation of four compounds. Their structures were characterized to be hentriacontane (1), palmitic acid (2), daucosterol (3) and 3-dihydrocaffeonyl-5-p-coumaroylquinic acid (4) by spectroscopic methods. The compounds (1~4) were for the first time reported from this plant. The solvent fractions were tested for their antioxidant activities by free radical scavenging and superoxide dismutase (SOD).

• 한국디지털정책학회:학술대회논문집
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• 2003.12a
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• pp.403-415
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• 2003

This study is performed to examine the relationships between trust and antecedents in cyberspace. Trust is the major control system in cyberspace. Different time, different spaces, different cultures, indistinct boundaries, flexible structure, separation of information from matters, cybernetics, difficulty of control are differential characteristics between cyberspace and physical space. Providing fit information, use of effective electronic channels, previous trust management, feedback system about output, flexible culture, self-regulation, off-line meeting, providing information about tasks and roles, ability, and justice are supposed to have effects on trust in cyberspace. By electronic mediated systems, the company will have more business opportunity. But trust will be conditional factors of expanding business in cyberspace.

• YAKHAK HOEJI
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• v.23 no.1
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• pp.7-10
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• 1979

A gas chromatographic determination of dienestrol in dienestrol cream has been studied. Dienestrol cream was dissolved in pyridine and silylation was done by using N, O-bis (trimethylsilyl) trifluoroacetamide. The derivative was injected into 3% silicone OV-17 column for chromatographic estimation. The dienestrol peak was found to be well separated from the other components of the cream. The detection limit was obtained to be $5.6{\times}10^{11}$ mol of dienestrol for this method. As there is no need for prior separation procedure, this experiment is extremely simple and less time consuming as compared to the conventional methods for estimation of dienestrol in cream.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.257-261
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• 1970

Some factors such as the weight ratio, reaction time and temperature for the separation of rare earth elements from monazite are studied. The influence of the inorganic phosphate for the leaching is also studied.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.655-656
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• 2009

Here we report a nano-sized polymer-dispersed liquid crystal (NPDLC) with an excellent scattering effect due to the maximized Mie scattering. We used a modified emulsification method combined with a limited coalescence mechanism. The fabrication process is simpler to obtain uniform nano-sized droplets rather than the conventional polymerizationinduced phase separation method.

• Structural Engineering and Mechanics
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• v.29 no.5
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• pp.551-565
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• 2008

Transient solution of asymmetric mechanical and thermal stresses for hollow cylinders made of functionally graded material is presented. Temperature distribution, as function of radial and circumferential directions and time, is analytically obtained, using the method of separation of variables and generalized Bessel function. A direct method is used to solve the Navier equations, using the Euler equation and complex Fourier series.