• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1383-1386
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• 2005

Non-isolated OSAKA Converter, which removes a three-phase transformer, is described in this paper. The converter switches once in every half cycle of an AC commercial power source. Therefore, it can solve many problems caused by the high frequency operation. The proposed converter achieves the soft-switching operation and the EMI noise can be reduced. In this circuit, the resonant capacitor, which is used for the soft-switching operation, is utilized for the improvement of an input current waveform. To achieve low cost and compact structure, non-isolated OSAKA converter removes a three-phase transformer of the OSAKA converter. By removing the three-phase transformer, three phase currents occur the interferences each other. To avoid the interference, a new switching method for non-isolated OSAKA converter is preposed. The converter can be constructed by the low-speed large power devices. The converter generates the low distorted input current waveforms with high power factor.

• Journal of Power Electronics
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• v.19 no.2
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• pp.413-430
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• 2019

This paper presents an optimum hybrid SVPWM technique for three-level voltage source inverters (VSIs). The proposed hybrid SVPWM technique aims to minimize total harmonic distortion (THD). A new parameter is introduced to incorporate the heterogeneous nature of switching sequences of SVPWM technique. The proposed hybrid SVPWM technique is implemented on a low-cost PIC microcontroller (PIC18F452) and verified experimentally with a 2 KVA three-phase three-level insulated gate bipolar transistor-based VSI. Optimum switching sequence results in the three-level inverter configuration are demonstrated. The proposed hybrid SVPWM technique improves the THD performance by 17.3% compared with the best available three-level SVPWM technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8222-8227
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• 2015

The visibility range is defined from where one can see, which can be changed by the character sizes and illuminances and so on, which of one-hundred and twelve students are measured for three illuminances and three character sizes in this paper. In determining the character sizes and illuminances, the visibility range can be an important data. Functions are proposed whose independent variable is illuminance and whose dependent variable is visibility range in order to predict the visibility range of unmeasured illuminances. The fractional functions are used for three character sizes because the visibility range is invariant according to illuminance. There are three parameters to be determined - k, m, n, which are selected based on the measured visibility ranges. Because the visibility ranges of three character sizes are measured, three k's can be calculated. In this paper the case of minimum variance of three k's is selected, and three parameters - k,m,n- of that case is selected. The three functions according to three character sizes are proposed. The small differences between the measured data and the postulated functions verifies the accuracy of the functions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.6
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• pp.492-501
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• 2016

Three-Loop autopilot is generally used for the acceleration control of guided missiles. Because the acceleration command to the three-loop autopilot is given as values at the center of gravity, feedback information of IMU should be obtained at the same position. However, the position of IMU might not be located at the center of gravity due to the sub-system assignment. This paper presents the stability analysis of three-loop autopilot with respect to the arbitrary position of IMU and variation rate of center of gravity. Gain and phase margins are calculated for several trim points for general anti-tank missiles.

• Korean Institute of Interior Design Journal
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• v.16 no.4
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• pp.39-46
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• 2007

The aim of this study was to recognize the need of three generation family house that is traditional house type of Korea. First, the pre-research analysis method was used for this study. And then, there are three type's grouping like those are as follows; 1) Recognition of three generation family house. 2) Type of three generation family house. 3) Plans of three generation family house. The analysis results are as follows; If the conditions are better than now, recognition is positive. Type are living together and next doors type can direct access. Some standart plan is been about room's number, house's area, bath's number and so on. Second, try to compare plan - this plan already has been used building - with standard plan. The compare result are as follows; three generation family houses - be used by whom - do not apply to standard plan. Almost houses have a three room that is less than the standard plan. All houses have a number of two bath that is less than the standard plan too. Condition of consideration is suitable to ages in next door type, but in case of living together type that consider user whom is use the inner room. Separation of entrance distinguish between the living together type and the next doors type. In case of living together type Dining with Kitchen room's number is one, but the next doors type have the number of two.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.261-270
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• 2021

In this study, the design methodology of LCL filter for grid-connected three-phase inverter was studied. First, the advantages and disadvantages of applying typical filter structures as a filter for grid connection of a three-phase inverter were analyzed. Next, filter design methodologies for grid connection of a three-phase inverter were analyzed, and an effective filter design methodology was determined to satisfy the harmonic requirements in grid connection. In order to verify the effectiveness of the design methodology, EMTP models such as a three-phase inverter, a three-phase LCL filter, and a performance evaluation system to evaluate the performance of the designed filter were developed using EMTP-RV. Next, an LCL filter was designed for an application example of a three-phase inverter, and the waveforms of the output voltage and outage current of the three-phase inverter were checked through EMTP-RV simulation work. In particular, the validity of the design methodology was verified by confirming that the magnitude of the current ripple was reduced to a limited magnitude through waveform analysis of the output current.

• Journal of the Korean housing association
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• v.6 no.2
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• pp.163-170
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• 1995

The purpose of this study is to investigate the college students' attitudes towerd caregiving and three-generation coresidencd of the future family living. In order to use its analysed results as a basic for the housing for the aged in Korea and to improve quality of their living environment. the number of 321 college students' in Taegu were surveyed and percent. crosstabulations were used to analysis the data. The result showed firstly that there was no difference in those college students' attitude toward caregiving to the old parents between sexes. and secondly that they had a potential sense of responsbilty of the eldst son of daughter for caragiving to the parents when considering the order of brothers and sisters. Thirdly the respondents of the female students were far more nagative for three-generation coresidence that that of the male students. Fourthly, there was no relation to the three-generation coresidenct regardless of the family form or the order of brothers and sisters. Fifthly, housing type based on the three-generation coresidence showed that they preferred an independent house with the size of 31-40 pyong. It was also shown that the room for the parents should be arranged in the best position.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.131-135
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• 2006

Many alternatives on the residential open building have been researched for corresponding high flexibility and possibility of remodeling in Korea as well. However, existing researches only dealt with two-dimensional floor plan. All buildings as well as apartment housing must have been examined various spatial aspect, three-dimensional not two-dimensional. It will examine basic method of three-dimensional flexible unit system to add to three-dimensional usage method overcoming these limitations. The purpose of this study is to propose the system of three-dimensional residential open building in Korea after examining possibility of flexibility of residential open building in 1.5 times of existing floor height.

• Korean Journal of Mathematics
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• v.20 no.3
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• pp.361-369
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• 2012

We get a theorem which shows the existence of at least six solutions for the semilinear wave equation with nonlinearity crossing three eigenvalues. We obtain this result by the variational reduction method and the geometric mapping defined on the finite dimensional subspace. We use a contraction mapping principle to reduce the problem on the infinite dimensional space to that on the finite dimensional subspace. We construct a three-dimensional subspace with three axes spanned by three eigenvalues and a mapping from the finite dimensional subspace to the one-dimensional subspace.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.97-102
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• 2002

Two dimensional Analysis has been applied to most of tunnel lining design in these days. Two dimensional analysis uses beam or curved beam element for finite element method. But because the behaviors of tunnel concrete lining structure is near to shell, it is required to model the tunnel lining as shell structure for safety design of tunnel lining structure. In this paper, two dimensional analysis by beam element and the three dimensional analysis by shell element of tunnel concrete lining are studied, in which 3 type of tunnel lining and lateral pressure factors are considered. As results of the study, three dimensional analyses of the behavior of tunnel concrete lining structure considering lateral pressure factor shows that the moment of three dimensional analysis is greater than those of two dimensional analysis. The results shows that three dimensional analysis is necessary for safety design of tunnel lining.