• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1071-1079
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• 2007

In this paper, a novel space vector control method for isolated multi-level inverter using 3-phase low frequency transformers is proposed. This method is based on the simplification of the space-vector diagram of a five-level inverter using calculated table into fully programming method. The execution time of the proposed method is about same as that of the method using calculated table. Also, the proposed method is easily applied to other case level inverter. We applied this method into the 3-phase IHCML inverter using common arm. It makes possible to use a single DC power source due to employing low frequency transformers. In this inverter, the number of transformers could be reduced compare with an exiting 3-phase multi-level inverter using single phase transformer. In addition, this method generates very low harmonic distortion operation with nearly fundamental switching frequency. Finally, We tested multi-level inverter to clarify electric circuit and reasonableness through Matlab simulation and experiment by using prototype inverter.

• Journal of Astronomy and Space Sciences
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• v.12 no.1
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• pp.44-53
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• 1995

BVRI observatins of AW UMa were made from March to April during 13 nights in 1994 using the 35cm Schmidt-Cassegrain telescope of Department of Astronomy and Space Science, Chungbuk National University. A total of 1092 observations (273 in B, 273 in V, 273 in R, 273 in I) were obtained. We constructed the light curves of BVRI with these observations. The one time of primary minimum light of JD Hel 2449456.1502 and the two times of secondary minimum light of JD Hel 2449456.1502 and JD Hel 2449447.1567 were determined from our observations. Orbital period change of -0.d00000394 was determined from O-C diagram which was constructed with collected times of minimum lights. Mass transfer rate of $-6.4\times10^{-7}M_\odot/year$ was derived using the period changing ratio. It is suggested that the inhomogeneous distribution of transferred matter around the secondary component would produce the irregular light variation of the AW UMa system.

• Publications of The Korean Astronomical Society
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• v.31 no.3
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• pp.43-56
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• 2016

Through time-series BV CCD photometry of the open cluster NGC 225 region, we have detected 30 variable stars including 22 new ones. They are five ${\delta}$ Scuti-type variable stars, a slowly pulsating B star, six eclipsing binary stars and 18 semi-long periodic or slow irregular variables, respectively. We have performed multiple-frequency analysis to determine pulsation frequencies of the ${\delta}$ Scuti-type stars and a slowly pulsating B star, using the discrete Fourier transform and linear least-square fitting methods. We also have derived the periods and amplitudes of 6 eclipsing binaries and a long-period variable star from the phase fitting method, and presented the light curves of all variable stars. A slowly pulsating B star is a member of NGC 225, but ${\delta}$ Scuti-type stars are not members from the positions in the color-magnitude diagram and the radial distancies from the center of the cluster. From Dias et al. (2014, A&A, 564, 79), only three variable stars including the slowly pulsating B star are members of clusters: two are in NGC 225 and one is in Stock 24. But a variable star in Stock 24 is not a member of the cluster because of its position of color-magnitude diagarm.

• Korean Institute of Interior Design Journal
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• no.39
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• pp.83-91
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• 2003

The planning of circulation area and circulation path are very important elements for layout of interior space of housing. This study is, therefore, aimed at synthetical review of that area from a functional, structural and socio-cultural point of view as well as typological analysis of that area. In the interior space of housing the networking of spaces according to the circulation route imply divers aspects of independent or dependant significances. It is thus, closely related with to whether circulation area open or closed, whether circulation path concentrated or distributed, and whether it passes Individual rooms or not. With regard to relationship with public and private spaces, there are many grounds for combining each other. This study also tried to develope program for planning of circulation system, utilizing typological analysis of them. At the same time this study suggests examples for layout of housing spaces. It is expected that the results represented In the form of systematic diagram will deserve to be a tool for providing an appropriate solution to the problem of diversity of user's needs.

• Journal of The Korean Astronomical Society
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• v.38 no.4
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• pp.429-435
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• 2005

We present BV CCD photometry for the open clusters Czernik 24 and Czernik 27. These clusters have never been studied before, and we provide, for the first time, the cluster parameters; reddening, distance, metallicity and age. Czernik 24 is an old open cluster with age $1.8{\pm}0.2Gyr$, metallicity $[Fe/H]=-0.41{\pm}0.15dex$, distance modulus $(m-M)_0=13.1{\pm}0.3mag$ ($d=4.1{\pm}0.5kpc$), and reddening $E(B-V)=0.54{\pm}0.12mag$. The parameters for Czernik 27 are estimated to be $age=0.63{\pm}0.07Gyr$, $[Fe/H]=-0.02{\pm}0.10dex$, $(m-M)_0=13.8{\pm}0.2mag$ ($d=5.8{\pm}0.5kpc$), and $E(B-V)=0.15{\pm}0.05mag$. The metallicity and distance values for Czernik 24 are consistent with the relation between the metallicity and the Galactocentric distance of other old open clusters. We find the metallicity gradient of 51 old open clusters including Czernik 24 to be ${\Delta}[Fe/H]/{\Delta}R_{gc}=-0.064 {\pm}0.009dex\;kpc^{-1}$.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.37 no.3
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• pp.93-107
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• 2019

The purpose of this paper is to explore the application of Chinese traditional garden space construction principle studied by predecessors in modern park landscape, and to find more methods of traditional garden space construction inheritance and innovation through research. Tian Chaoyang's book "Fifteen Lectures on Chinese Classical Gardens and Modern Translation" mentions that Chinese traditional gardens are combining time and space, so he draws a brief pattern diagram containing the principle of the space construction. According to this principle of space construction, the researchers chose Qujiang Pool Heritage Park, which combines modern and traditional, then analyzed its spatial structure and and space elements. The results are as follows. The complex spatial structure of the park is composed of spatial boundary lines and spatial routes. The complex boundary space is composed of bridges, squares, plants, rows of buildings and other elements. The water space in the center of the park is designed in accordance with the traces of the historical water system, and its natural zigzag shoreline expands the water space. The central water space is divided into the big pool and the small pool, the Yanbo island and Bird island are created respectively. The building at the park boundary connects the park's interior and exterior. Most of the buildings in the park are located in the convex corner of the route or space. Through this research, it can be concluded that Qujiang park also applies the space construction principle combining time and space. And then, the garden elements of Qujiang park are recreating the history and culture of Qin, Han, Sui and Tang dynasties with modern methods, thus creating a park with Chinese regional characteristics. Since the Tang dynasty was the most prosperous period in Qujiang, the park was dominated by Tang culture. Through the research of this paper, we can see that the space construction principle of Qujiang Pool Heritage Park is the inheritance of the space construction principle of Chinese traditional garden. And the landscape element of Qujiang park is the landscape created by combining traditional history and culture, which is the innovative part of modern garden. Through this study, the creation of modern landscape with Chinese characteristics can provide some hints on the direction of inheritance and innovation.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.688-692
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• 2010

Wireless sensor network system collects and analyzes real-time data that have been requested by the many application nodes. This paper has constructed a sensor network cluster with various elements in the Gunsan City area of Jeollabuk-do, S.korea. The purpose of this paper is to utilize the constructed system in order to illustrate the real-time data in a diagram and analyze it to deduce the change ratio. The resulting analysis contents allow simple data interpretation by illustrating the data in change ratio by time, space, and motional directions. This analytical method will offer great benefit to those users using the wireless sensor network.

• Journal of The Korea Institute of Healthcare Architecture
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• v.25 no.3
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• pp.15-23
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• 2019

Purpose: As the medical laboratories in general hospitals have made an efforts on quality management and employee health, they recognized the need of design guideline for clinical laboratory. As laboratories are prohibited to patients, their environments are becoming more congested and deteriorated as time goes by. So, this study investigates the current status of facility and equipment of laboratory medicine focusing on less than three hundred patient bed hospitals, and searches the improving matters. Methods: Questionnaires to technologist captains and field surveys to medical laboratories in korean hospitals have been conducted for the data collection. 18 answers have been analysed statistically by MS Excel program. Results: The result of this study can be summarized into followings. Clinical laboratory functions are all hematology, clinical chemistry, immunology, transfusion and urine microscopy, and except for three including microbiology for infection and bio safety level. Average man power of lab are 12.3 man including lab director and captain. Patient bed number, space area and total specimen numbers are not correlated with each other, but specimen numbers and employee number are correlated with. Work space distances are usually good, but exit distances are not adequate for escape owing to obstacles. Specimen delivery system by courier, test method by automatic analyzer, access floor for exposed plumbing and electricities are more practical. Open lab layed out in the center and lab support layed peripheral in space diagram. Lab space configuration by SD method showed that lab support area and employee support area are dissatisfied. Implications: Specialized hospital and yearly total specimen numbers are related to the space area and organization for laboratory planning and design.

• Journal of the Korean association of regional geographers
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• v.12 no.5
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• pp.583-594
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• 2006

Relics are life traces of ancestors, and they are good data for giving an idea about space locations of that period. This study classifies relics according to their type, and for each classified group metrical analysis is carried out using GIS and triangle diagram. The criteria used for analysis of relics' locations are elevation, road accessibility and water accessibility. The analysis results show that every relic has its own distribution characteristics according to the time and the type. This means high possibility of approaching a geographical focus on relics distribution and location. While historical period was taking over prehistorical, relics locations moved from the points of great usage water supply possibility to the points of great traffic accessibility. Also, relics of the ruling class for each time period generally have good locations.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.60.1-60.1
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• 2015

High energy photons and mechanical energy produced by the process of star formation result in copious FIR molecular and atomic lines, which are important coolants of the system. Photons thermally or mechanically induced could dissociate water in the dense envelope to change relative abundances among the species of O, OH, and H2O. Here we analyze OH emission lines toward embedded young stellar objects (YSOs) observed as part of the Herschel open time key program, 'Dust, Ice, and Gas In Time (DIGIT)' in order to study the physical conditions of associated gas and the energy budget loaded on the OH line emission. According to our analysis of the Herschel/PACS spectra, OH emission peaks at the central spaxel in most of sources, but several sources show spatially extended emission structures. In the extended emission sources, the distribution of OH emission is correlated with that of [OI] emission and extended along the outflow directions. Considering the diversity of source properties, ratios between detected OH lines are relatively constant among sources. In addition, each OH line has strong correlation with bolometric luminosity. In order to determine the physical conditions of YSOs, we adopt several methods for the analysis of the OH lines: rotational diagram, non-LTE LVG analysis, and a 2-D PDR code. From the simple LVG analysis, we find that the thermal solution with the dense ( > $10^7cm^{-3}$) and warm ( ~ 100 K) OH gas reproduces the ratios of detected OH lines. However, our self-consistent PDR 2-D model, which can deal with the IR-pumping effect from the central protostar as well as the warm dust in situ, cannot fit the observational results, suggesting that an irradiated shock model is necessary for a better interpretation.