• Journal of the Korean Chemical Society
• /
• v.52 no.6
• /
• pp.657-662
• /
• 2008

• Journal of Astronomy and Space Sciences
• /
• v.5 no.2
• /
• pp.97-109
• /
• 1988

The photometric behaviour of XY U Ma, an eclipsing binary showing photospheric and chromospheric activity, has been described by spot hypothesis. They are based on the all the available UBV light curves, which were carried out by Geyer since 1955. A "spherical rectangular" spot model shows very pronounced spot activities during the last 30 years. On the average, the spot covered about 16% of the visible hemisphere. Observational evidence for photospheric and chromospheric activities on the XY UMa and related systems are also discussed.

• East Asian mathematical journal
• /
• v.24 no.3
• /
• pp.213-221
• /
• 2008

In this paper, a new class of fuzzy topological spaces called ordered fuzzy pre-extremally disconnected spaces is introduced. Tietze extension theorem for ordered fuzzy pre-extremally disconnected spaces has been discussed as in [9] besides proving several other propositions and lemmas.

• Journal of the Korean earth science society
• /
• v.27 no.6
• /
• pp.695-700
• /
• 2006

We present B, V, I time series CCD photometry for the variable star TU UMi to classify its variable type. The observations were performed using 61cm telescope equipped with 2K CCD camera at Sobaeksan Optical Astronomy Observatory (SOAO). Judging from the amplitude ratio $({\Delta}i/{\Delta}v)$ and color variation $({\Delta}(b-v),\;{\Delta}(v-i))$. TU UMi should be a W UMa type eclipsing binary. We obtained two primary times of minimum lights (HJD 2453848.0446, HJD 2453848.2309) from our observations and determined new orbital elements (Min I=HJD 2452500.1344+0.37708907${\times}$E) for TU UMi.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.1 s.45
• /
• pp.253-260
• /
• 2007

A multimedia converter is used to create media suitable for own environment. If the data complying with own demands can not be created, it may accompany with a problem that has to convert the data with another transcoder. In addition, conventional converters do not consider source QoS and target QoS sufficiently, meaning that users should have a significant knowledge base about various media in order to obtain desired results. These problems become limits on the UMA(Universal Multimedia Access) environment. In this paper, we create a suitable transcoding path before performing the Digital Item conversion in consideration of source QoS and target QoS. The created transcoding path performs the adaptive transcoding using unit exchanges featuring connectivity. The consideration of QoS allows users to use the multimedia easily. Since the proposed model, in addition, use the unit transcoder, it provides a excellent adaptive capability for new QoS.

• Smart Structures and Systems
• /
• v.16 no.4
• /
• pp.623-640
• /
• 2015

This paper presents techniques to harvest higher voltage from piezoelectric cantilever energy harvester by structural alteration. Three different energy harvesting structures are considered namely, stepped cantilever beam, stepped cantilever beam with rectangular and trapezoidal cavity. The analytical model of three energy harvesting structures are developed using Euler-Bernoulli beam theory. The thickness, position of the rectangular cavity and the taper angle of the trapezoidal cavity is found to shift the neutral axis away from the surface of the piezoelectric element which in turn increases the generated voltage. The performance of the energy harvesters is evaluated experimentally and is compared with regular piezoelectric cantilever energy harvester. The analytical and experimental investigations reveal that, the proposed energy harvesting structures generate higher output voltage as compared to the regular piezoelectric cantilever energy harvesting structure. This work suggests that through simple structural modifications higher energy can be harvested from the widely reported piezoelectric cantilever energy harvester.

• Journal of The Korean Astronomical Society
• /
• v.25 no.1
• /
• pp.47-64
• /
• 1992

Cores of globular clusters are an ideal place for close encounters between stars. The outcome of tidal capture can be stellar mergers, close binaries between normal stars (W UMa type), cataclysmic variables composed of white dwarf and normal star pairs, or low-mass X-ray binaries consisting of a neutron star and a normal star pairs. Stellar mergers can be the origin of blue stragglers in dense globular clusters although they are hard to observe. Low mass X-ray binaries would eventually become binary pulsars with short pulse periods after the neutron stars accrete sufficient amount of matter from the companion. However, large number of recently discovered, isolated millisecond pulsars (as opposed to binary pulsars) in globular clusters may imply that they do not have to gain angular speeds during the X-ray binary phase. We propose that these isolated millisecond pulsars may have formed through the disruptive encounters, which lead to the formation of accretion disk without Roche lobe filling companion, between a neutron star and a main-sequence star. Based on recently developed multicomponent models for the dynamical evolution of globular clusters, we compute the expected numbers of various systems formed by tidal capture as a function of time.

• Publications of The Korean Astronomical Society
• /
• v.22 no.2
• /
• pp.35-41
• /
• 2007

We present the result of radial velocity observation of a W UMa type binary star EX Leo. We observed the star on February 16, 2003, using Long-Slit spectrograph of BOAO(Bohyunsan Optical Astronomical Observatory). Since the spectral lines are broad due to its fast rotation, it is difficult to distinguish two radial velocities from cross correlation function. Instead of cross correlation function, we used broadening function to develop our own code which estimate the radial velocity of the broadened line spectra. With our own code, radial velocities of primary and secondary stars are derived simultaneously. From the radial velocity curve fit, we obtained $K_1=50.24{\pm}8.29km/s$ and $K_2=254.05{\pm}20.984km/s$ respectively.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2004.10a
• /
• pp.259-279
• /
• 2004

[ $\box$ ] 방송통신 융합의 가속화 $\box$ 통방융합의 Business Models $\box$ 이종망을 통한 다양한 단말에서의 콘텐츠 서비스 $\blacksquare$ Ubiquitous Content Access - Anytime, Anywhere, Any Contene $\box$ 멀티미디어 프레임워크 필수적 - 상호연도 가능한 콘텐츠 생성/보호, 전달, 적응/소비 제공 $\box$ 통방융합 멀티미디어 프레임워크 기술 개발 추진 $\box$ MPEG-21 Multimedia Framework에 기반한 핵심기술 개발 $\blacksquare$ Content Adaptation & Personalization - MPEG-21(DIA), MPEG-7, TV-Anytime Forum $\blacksquare$ End-to-end Qos $\blacksquare$ Scalable Video Coding & Delivery, etc $\box$ UMA 기술 $\box$ EU Project : ENTHRONE

• Journal of Astronomy and Space Sciences
• /
• v.5 no.1
• /
• pp.73-79
• /
• 1988

New differential photoelectric observations in UBV system of the W UMa-type eclipsing binary SW Lac presented. The data were obtained on 4 nights from October in 1987 using the 61cm reflector at Sobaeksan Astronomical Observatory. These light curves are compared with recent published light curves in order to check the light curve variations and magnitude difference of minimum light phases. Four times of minimum light are deduced and the orbital period variation of SW Lac has been discussed.