• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.66.2-66.2
• /
• 2010

We have studied the properties of interstellar turbulence as observed by Boston University-Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS). This observation uses 13CO J=$1{\rightarrow}0$ emission with high spectral resolution of 0.21 kms-1 and covers wide galactic plane regions ($18^{\circ}$ < 1 < $55.7^{\circ}$ and -1 < b < $1^{\circ}$). Firstly, we measured the one dimensional power spectrum of 13CO intensity along the galactic longitude and along the galactic latitude. We found the slope of the power spectrum changes around the molecular ring structure and the center of the galactic plane. Secondly, we explored how the power spectral slope is related with the velocity dispersion of supersonic giant molecular clouds in the GRS. Finally, we suggest the turbulent nature of the interstellar medium is connected with star formation activities in spiral arms.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.33 no.11
• /
• pp.425-432
• /
• 1984

This paper is to propse a new self-excitation method of synchronous generator. Instead of conventional exciter of synchronous generator, the additional winding which is arranged in addition to the armature winding, is used in this generator. The output terminal of the additional winding is connected to a capacitor and to a full wave rectifier in series. In this configuration, one source double excitation which is composed of capacitor-self-excitation by lead urrent and direct current excitation by rectifier, is induced. The result is that` The excetation efficency is improved greatly and output waveform is improved also. In three-phase synchronous generator using the new method of the one source double excitation, voltage element (shunt characteristics) and current element (series characteristics)are compounded in scalar by adapting star-point-open-rectifier system. The result is as following` The effect of load power factor angle on voltage regulation is reduced greatly, compound characteristics is become manifold by controlling capacity of capacitor, and transient response is improved.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1523-1525
• /
• 1994

This paper describes a proposed very fast transient overvoltages(VFTO) measurement system suited for established gas insulated switchgear(GIS). The detecting system consists of a shield electrode connected to a buffer amplifier, and the transmission of the detected signal to an oscilloscope is made through an optical fiber. The bandwidth of the measurement system is 5 Hz to 30MHz. When determining the voltage dividing ratio by use of the commercial frequency voltage, the error is less than 0.5 %. Also, the data were obtained by the electric field probe and the high voltage probe, and their deviation for voltage dividing ratio were less than 1 %.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.599-601
• /
• 2015

The short time scale X-ray variability associated with the accretion disk around compact objects is complex and is vaguely understood. The study of the cross correlation function gives an insight into the energy dependent behavior of the variations and hence connected processes. Using high resolution RXTE data, we investigate the dynamical cross correlation function of an observation of a black hole source XTE J1550-564 in the steep power law state. The cross correlation between soft and hard X- ray energy bands revealed both correlated and anti-correlated delays (${\leq}{\pm}15s$) on a correlation time scale of 50 s. It was noticed that the observed delays were similar to the delays between X-ray and optical/IR bands in other black hole and neutron star sources. We discuss the possible mechanisms/processes to explain the observed delays in the dynamical CCF.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.810-812
• /
• 2003

The dynamic characteristics of a three phase induction motor which is applied by various unbalanced voltages are simulated and analyzed in this paper. The voltage equations and torque equation in the dq stationary reference frame for the three phase star connected induction motor are used in this analysis. MATLAB and SIMULINK are employed as a simulation tool. The dynamic characteristics of speed and torque are simulated for various unbalanced voltages, that is, (1) cases with the same unbalance voltage factor but different unbalanced voltages, (2) cases with only one unbalanced voltages but different degree of unbalance, and (3) cases with the same positive sequence voltage but different negative sequence voltages. The simulated results are compared and analyzed with each other, and also with the results of balanced voltage.

• International journal of advanced smart convergence
• /
• v.10 no.1
• /
• pp.89-96
• /
• 2021

The goal of this study is to develop experiment monitoring system of agriculture fields using ZigBee wireless modules. Soil moisture, ambient temperature, atmospheric pressure and intensity of sunlight are the most important factorsto grow a wheat crop and other vegetables. In orderto monitorthe factorssoil moisture (YL69), air pressure (BMP180), temperature (DS18B20), photoresistor were used for sensing environment data. The TI CC2530 RF SoC chip was used in the system. ZigBee modules were connected to star topology. ZigBee modules send data wirelessly to a data center. This data can be displayed and analyzed on the main monitoring program as needed also sent to the client mobile. Characteristics of the sensors were determined by experiment results.

• Journal of the Korean Society for Railway
• /
• v.12 no.4
• /
• pp.457-464
• /
• 2009

The now velocity distribution at inlet of diesel Particulate filter (DPF) which is connected to each curved duct was simulated using $STAR-CD^{(R)}$. Three kinds of models which describe the shapes of the curved duct ware used for the CFD simulation. The simulation results were compared with the experimental data of velocity distribution which was obtained using a Pitot tube and 2-D positioning machine. At the $90^{\circ}$ curved connecting condition, the CFD simulation results of flow velocity distribution at inlet of the DPF showed a horse hoop shape shifted from the axial center line of the DPF. The CFD simulation results agree reasonably with those of the experiments.

• Journal of Korean Association for Spatial Structures
• /
• v.12 no.1
• /
• pp.59-68
• /
• 2012

The space frame structure is one of the large span structural system consisting of longitudinal and latitudinal members. The members are connected in three dimension. A space frame structure has high stiffness with a structure resisting external forces in steric conformation. According to many structural conditions, structural stability problems in the space frame are determined and considered very important. This study seeks to understand the space frame collapse mechanism using the 2-free nodes truss model in order to examine static structural instability characteristics of the latticed dome. According to geometrical shape, the star dome, parallel lamella dome and three way grid dome were selected as models. The models were examined for characteristics of instability under STEP Excitations behavior according to rise-span ratio(${\mu}$) and shape imperfection.

• The Research Journal of the Costume Culture
• /
• v.16 no.2
• /
• pp.382-396
• /
• 2008

The purpose of this study is to analyze the transition of glamour style expressed in modern fashion throughout the history. The glamour style in modern fashion was categorized into five periods which are Hollywood glamour(H), Feminine glamour(F), Rich glamour(R), Decadent glamour(D), and Trash glamour(T). These categories were analyzed and compared in the viewpoint of aesthetic values deduced on the previous study. As a method of analysis, literature study and case study through the publications in aesthetics, history and preceding theses were used. The results of analysis are: Ostentatious luxury was suggested by extravagance of the movie star in H, the splendid American lifestyle in F, conspicuous consumption in R, fin de siecle bad taste in D and self-assured exposure in T. Mysterious idolatry was studied as exaggerated goddesshood of the movie star in H. It was expanded to celebrities including fashion models, television actresses, pop singers and young couture designers in the other periods. Artificial sensuality was originated from the femme fatale image of the courtesan as well as the traditional femininity of Victorian era in H. It was developed through exaggerated hourglass silhouette of the wife dressing in F. But an aggressiveness in R, a hyper-sexual femme fatale in D, an independent and defiant image of the showgirl in T were observed. Playful queerness stood out clearly by the fin de siecle phenomena. Though it was embodied in sexual perversive subculture, it emerged as hi fashion by young designers in the late R and became a crucial aesthetic value throughout D and T. It is more connected with the origins of glamour which arouses sexual ambiguity, crudity, aggressiveness and death. The continuity and discontinuity of the glamour style based on the theory of 'linked solution' were also analyzed.

• Journal of the Korea Society of Computer and Information
• /
• v.13 no.2
• /
• pp.221-233
• /
• 2008

In general, we use a Parallel processing computer manufactured specially for the purpose of parallel processing to do high performance computings. But we can depoly and use a PC cluster composed of several common PCs instead of the very expensive parallel processing computer. A common way to get a PC cluster is to adopt the star topology network connected by a switch hub. But in this paper, we grope efficient implementations of hypercube networks based on TCP/IP to connect 8 PCs directly for more useful parallel processing environment, and make evaluations on functionality and efficiency of them using ping, netperf, MPICH. The two proposed methods of implementation are IP configuration based on link and IP configuration based on node. The results of comparison between them show that there is not obvious difference in performance but the latter is more efficient in simplicity of routing table. For verification of functionality, we compare the parallel processing results of an application in them with the same in a star network based PC cluster. These results also show that the proposed hypercube networks support a perfect parallel processing environment respectively.