• Journal of Advanced Information Technology and Convergence
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• v.8 no.2
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• pp.59-67
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• 2018

The minimum power supply voltage of a typical bandgap current reference (BGCR) is limited by operating temperature and input common mode range (ICMR) of a feedback amplifier. A new BGCR using a bandgap voltage generator (BGVG) is proposed to minimize the effect of temperature, supply voltage, and process variation. The BGVG is designed with proportional to absolute temperature (PTAT) characteristic, and a feedback amplifier is designed with weak-inversion transistors for low voltage operation. It is verified with a $0.18-{\mu}m$ CMOS process with five corners for MOS transistors and three corners for BJTs. The proposed circuit is superior to other reported current references under temperature variation from $-40^{\circ}C$ to $120^{\circ}C$ and power supply variation from 1.2 V to 1.8 V. The total power consumption is $126{\mu}W$ under the conditions that the power supply voltage is 1.2 V, the output current is $10{\mu}A$, and the operating temperature is $20^{\circ}C$.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.85-92
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• 2020

Ground hot-firing tests were conducted to analyze the combustion performance according to the characteristic lengths 1.37 m, 1.71 m, and 2.06 m of the combustion chamber in 200 N-class GCH4-LOx small rocket engine. Thrust, specific impulse, and characteristic velocity at the steady-state could be obtained as the key performance parameters of the rocket engine. The performance characteristics acquired through the test were compared and analyzed with the theoretical performance calculated from CEA analysis. Observation of the influence of characteristic length on the combustion performance indicates that an optimal characteristic length shall remain between 1.71 m and 2.06 m.

• Journal of Korea Water Resources Association
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• v.36 no.4
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• pp.533-545
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• 2003

This study analyzed several storm events observed in the Seolma-chun basin to derive the characteristic velocity of GIUH (Geomophological Instantaneous Unit Hydrograph) as well as its variability. Especially, this study focused on the variation of characteristic velocity due to the change of rainfall characteristics. The IUH of the Seolma-chun basin was derived using the HEC-1, whose peak discharge and time were then compared with those of the GIUH to derive the characteristic velocities. The characteristics velocities were analyzed by comparing with the GcIUH (Geomorphoclimatic IUH) as well as the characteristics of rainfall. Results are summarized as follows. (1) The characteristic velocity of GIUH was estimated higher with higher variability than the GcIUH, but their trends were found similar (2) Total amount of effective rainfall (or, mean effective rainfall) well explains the characteristic velocity of GIUH. This could be assured by the regression analysis, whose coefficient of determination was estimated about 0.6. (3) The duration and the maximum intensity of rainfall were found not to affect significantly on the characteristic velocity of GIUH. The coefficients of determination were estimated less than 0.3 for all cases considered. (4) For the rainfall events used in this study, the characteristic velocities of GIUH were found to follow the Gaussian distribution with its mean and the standard deviation 0.402 m/s and 0.173 m/s, respectively. Most of the values are within the range of 0.4∼0.5 m/s, and its coefficient of variation was estimated to be 0.43, much less than that of the runoff itself (about 1.0).

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.117-122
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• 2008

Generally, water is taken through channels and rivers, in which there are many weirs and structures, which cross rivers and temporally hold up water. But this way has its own shortcomings. It is main reason that the water flows through structures, and backwater come into being. So it causes many water quality problems and some flood side-effects and so on. In this study, among the various movable weirs, we installed bottom-discharged and air pressure movable weir in the experimental channel. And we analyzed flowing influence, which is followed by the angle variation of movable weir. We also make further study the flow characteristic variation followed by installing entrance at the bottom to discharge the bottom water. The analysis result was that installed weir angle was increased, and the discharge also gradually increased. The installed weir angle depended on the water quantity, which can be excluded in the bottom. In case of velocity, there was increased as maximum 21.9 times, according to there is entrance or not at the bottom. And in case of water level, it showed the water level of locally above the average decrease in the upper river of weir.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.523-532
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• 1994

A knowledge of the accurate characteristic impedance of a GTEM cell is very useful to design it. This paper discusses the characteristic impedance of a GTEM cell applicable to both susceptibility and emission measurements, considering opening angle of it. The over-RGM for analysis is described : this numerical method is operated with respect to the spherical coordinate system. Some results are compared with others and the validity of this analysis is estabished. The characteristic impedances of a GTEM cell with the variation of geometrical constructions on cross section are presented ; the effect of the opening angle on the characteristic impedance is show. Finally, the electirc field uniformities on a cross section of a GTEM cell are considered for various opening angles.

• Journal of Korean Society of Rural Planning
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• v.14 no.1
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• pp.1-7
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• 2008

Recently, brick pavement were widely introduced on the pavement in rural area. A variety of vision effects can be created from patterns of brick pavement. However, in most of brick pavement works, human psychological characteristics were not concerned. The purpose of this research was to discover psychological effect on brick pavement pattern. The results of the research can be summarized as follows: 1)Psychological impression on brick pavement pattern is similar among man and woman groups. 2)Stack bond and running bond pattern have a simple, relaxed, organized, and comfortable psychological characteristics. Basket weave & stack bond pattern has a simple and organized psychological characteristic. Herringbone bond pattern has a complex, dislike and uncomfortable psychological characteristic. Pinwheel bond pattern has a highly complex psychological characteristic. Basket weave and Basket weave variation bond pattern have a common psychological characteristic. 3)Employment of brick pavement pattern on this research is not highly preferred, hence it is necessary to develop a brick pavement patterns that have human psychological characteristics be concerned.

• Journal of the Korean Institute of Educational Facilities
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• v.16 no.4
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• pp.71-78
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• 2009

After the introduction of the 7th revision of curriculum, educational facilities have been requested to change to face new curriculums and have been planned. But, it is actual condition that researches of curriculum and facilities seem to be insufficient. This research will re-establish in an angle of space-syntax based on existed research for home-base area of variation type in high school according to the 7th curriculum. And the each specific character of home-base area representing each type and strong / weak points of area structure of each home-base will be analyzed. And analysis result with the model of variation type in high school visit the on-the-spot inspection result which leads and comparison and with his interview back it leads and currently there is the objective to the evaluation the variation type in high school home-base which is planned regarding the suitable in real use. Each case to the school I visited the scene, not all high schools applied the 7th curriculum courses. Therefore, it is also home-base space capabilities were not being properly utilize. According to 7th curriculum, one of Hall-type home-base and Room-type home-base can be suitable when integration is higher. However, the way the current operational training, it is the best that Distributed-type home-base needs to be included in each curriculum block.

• Journal of the Korean Society of Costume
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• v.59 no.4
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• pp.67-81
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• 2009

This study aims to characterize the effect of different combinations of chromatic-achromatic colors and 1:2:3 area-ratio variation of stripe necktie, and gender on the image of male wearer. The experimental materials developed for this study are a set of stimuli and response scales. The stimuli consist of 84 color pictures manipulated with every combination of 12 different colors and 7 different area-ratio. The 7-point scale designed for visual evaluation of image formation included 26 bipolar adjectives. The subjects were 2016 undergraduate students in Gyeongnam, Seoul, Busan, and Daegu areas. The results of this study were as follows. The analyses of images of male wearer in terms of combinations of chromatic-achromatic colors and I :2:3 area-ratio variation of oblique stripe necktie reveal that the concerned factors are of five characteristic dimensions of youth-activity, ability, attractiveness, appeal, and warmness. In addition, it has been found that individual images of male wearer are affected by observer's gender as well as combinations of chromatic-achromatic colors and 1:2:3 area-ratio variation of stripe neckties and that those images vary with every combination of each factor. The study results are highly expected to be used as useful sources in developing necktie designs.

• Journal of Industrial Technology
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• v.36
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• pp.17-22
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• 2016

A circular pin fin (CPF) and a half circular pin fin (HCPF) are by using the one-dimensional analytic method. For these two fins, 90% of the maximum heat loss, Corresponding fin length for 90% of the maximum heat loss, fin effectiveness and fin efficiency are compared as functions of convection characteristic number and fin radius. Also, the ratio of heat loss from the HCPF to that from CPF listed with variation of fin length when the fin volumes are the same. One of the results shows that the efficiency of a CPF is larger than that of a HCPF while the effectiveness of a CPF is smaller than that of a HCPF when convection characteristic number, fin length and fin radius are the same.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.244-246
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• 1996

In an controlled electric machine, the variations of motor parameters such as stator and rotor time constant are caused by the temperature rise, thus it is needed to calculate the accurate parameter through the dynamic characteristic analysis considering the temperature variation. In this paper, the dynamic characteristic analysis method of vector controlled LIM is proposed using coupled magnetic & thermal 2D FEM taking into account the movement.