• 한국전산유체공학회지
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• 제20권4호
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• pp.14-20
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• 2015

Without electirc power to cool down the hot reactor core, passive systems utilizing natural circulation are becoming a big specialty of recent neculear systems after the severe accident in Fukusima. When we consider the natural circulation in a pool, thermal mixing phenomena may start from single phase circulation and can continue to two phase condition. Since the CUPID code, which has been developed for two-phase flow analysis, can deal with the phase transition phenomena, the CUPID would be pertinent to natural convection problems in single- and two-phase conditions. Thus, the CUPID should be validated against single- and two-phase natural circulation phenomena. For the first step of the validation process, this study is focused on the validation of single-phase natural circulation. Moreover, the CUPID code solves the fluid properties by the relationship to pressure and temperature from the steam table considering non-condensable gas effects, so that the effects from variable properties are included. Simple square thermal cavity problems are tested for laminar and turbulent conditions against numerical and experimental data. Throughout the investigation, it is found that the variable properties can affect the flow field in laminar condition, but the effect becomes weak in turbulence condition, and the CUPID code implementing steam table is capable of analyzing single phase natural circualtion phenomena.

• 한국정보통신학회논문지
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• 제21권2호
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• pp.245-251
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• 2017

제안된 가변 전력 분배기는 입력된 신호를 동일한 신호 전력으로 분배하는 2-way 윌킨슨 전력 분배기, 90도 위상변화가 가능한 두 개의 가변 위상 변환기, 두 개의 경로 신호를 결합하는 브랜치라인 커플러로 구성된다. 제안된 가변전력 분배기는 이론적으로 가변 위상 변환기의 90도 위상 변화에 의해 브랜치라인 커플러의 두 개 출력 단자에 ${\infty}:1$에서 ${\infty}:1$까지 전력 분배 비율로 출력할 수 있다. 제안된 가변 전력 분배기는 중심주파수 1.7 GHz에서 Taconic사의 TLX-9 20mil을 이용하여 제작해 동작 특성을 확인하였다. 제작된 회로는 1.7 GHz에서 두 개 출력 단자에 1:100에서부터 200:1까지 전력 분배 비율의 변화가 가능하였으며, 1.65-1.75 GHz 주파수 대역에서 다양한 전력 분배 비율에 대하여 입력 반사계수 약 -16 dB 이하, 삽입 손실 약 -1.0 dB, 두 출력 단자의 격리 특성 약 -17 dB 이하의 안정적인 특성을 보였다.

• 대한전기학회논문지
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• 제41권7호
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• pp.773-783
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• 1992

There have been several control schemes for the single input systems with unmeasurable state variables using variable structure control(VSC) theory. However, each of them is a study on the systems which can be represented in the phase canonical form or non-phase canonical form dynamic equation separately. As these control algorithms have difficulties in practical application by its theoretical limitations, in this paper we propose a new VSC theory which overcomes those limitations, in this paper we propose a new VSC theory which overcomes those limitations of proposed schemes. This new control scheme can be realized for the general linear systems which have unmeasurable state variables. And the switching function of this VSS algorithm consists of measurable state variable function(reduced-order switching function) and its derivatives. Also in the construction of control imput only measurable state variables are used.

• 한국운동역학회지
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• 제13권1호
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• pp.73-94
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• 2003

The purpose of this investigation was to analyze A kinematic analysis of the Kuzushi-arm motion when performing Morote-Seoinage in judo who was 5 females university representative judokas of light weight category in judo, and filmed on video cameras(60field/s). The data of this study digitizied by KWON3D 2.1 program computed the average and standard deviation calculated individual 5 trials with Programing Lab view 6i. From the data analysis & discussion, the following conclusions were drawn : 1) distance variable of attacking hand arm in kuzushi motion Left right(X direction) displacement variable was all of A, B, C pattern with moving left to right and leaning. Strip of displacement variable was ordo. to C(55.6cm), A(53.3cm), B(43.9cm) pattern, C pattern largely leaned to left Front Rear(Y direction) displacement variable was different A($131.3cm{\pm}3.1cm$), B($128.7{\pm}4.0cm$) and C(111.0cm) on ready position, 3 pattern leaned to rear direction. Strip of displacement was order to B(43.4cm), A(41.1cm) and C pattern(28.3cm). Up down(Z direction) displacement variable was all of A, B, C pattern leaned to up in the Kuzushi-phase and leaned to down in the Kake-phase. Strip of displacement was order to A(83.9cm), B(80.4cm), C pattern(71.9cm). 2) Shoulder joint angle variable Flexion and extension Ready position' angle was A($138.3{\pm}4.9^{\circ}$), B($142.9{\pm}3.7^{\circ}$) and C($164.5^{\circ}$) pattern, strip of flexion extension was order to C($80.9^{\circ}$), A($79.9^{\circ}$) and B($39.0^{\circ}$) pattern, greatly C pattern had largely angle change. Adduction and abduction : B and C pattern's angle change were adduction and abduction in the Kuzushi-phase after adduction in the Kake phase, A pattern's angle change was abduction in the Kuzushi-phase after adduction in the Kake phase. internal and external rotation : 3 pattern were internal rotation in the Tsukuri phase and external rotation in the Kake phase. After B and C pattern were external rotation and A pattern was internal rotation. 3) Elbow joint angle variable Flexion and extension 3 pattern's ready position angle were A($142.0{\pm}4.4^{\circ}$), B($123.5{\pm}5.5^{\circ}$) and C($105.5^{\circ}$) and flexion. Strip of flexion extension were order to A($57.9^{\circ}$), C($34.6^{\circ}$) and B($25.2^{\circ}$) pattern.

• Journal of applied mathematics & informatics
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• 제7권1호
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• pp.237-245
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• 2000

In this paper, we consider to the adjustment weighting procedure in the two phase sampling scheme. In general, the unit nonresponses may be occured in the final survey operation. When the unit nonresponse be generated in survey, it is able to use the auxiliary variable for estimating of interest variable. In this viewpoint, we use the two kinds level of auxiliary variable, $X_{1k}$ and $X_{2k}$ for the calibration procedure. We proprose the two-step Newton's method in the calibration estimation procedure for the two phase sampling.

• Journal of Advanced Marine Engineering and Technology
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• 제22권4호
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• pp.538-550
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• 1998

The variable frequency and variable voltage AC source made by a conventional inverter which is composed of power semi-conductors includes much noises in sine wave due to high frequency switching of DC source. In this paper the 3rd low pass LC filter for a variable speed 3 phase induction motor driven by a full bridge inverter is introduced to solve the EMI problem by serious noise current. The utility of a modified 3rd order Butterworth LC filter is confirmed through FFT analysis of sine waves and noiseless ACsource can be obtained by the proposed LC filter. The speed of a 3 phase induction motor driven by a full bridge inverter with a LC filter is satisfactorily controlled by a digital PID controller under the condition of stepwise load and setpoint changes.

• Journal of Power Electronics
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• 제11권3호
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• pp.285-293
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• 2011

This paper proposes two SRM driving systems using a variable dc-link voltage controlled by a single-phase inverter. Two SRM converter topologies of a half bridge type and a full bridge type are proposed according to the power circuits of an inverter. The phase current can be controlled by means of a PWM controller at the inverter, and the turn-on/off angle at the phase switches can be controlled by a position sensor at the converter in the drive system. The inverter acts as a peak-current limiter if the transient current exceeds its maximum value. SRMs using the proposed topologies maintain high efficiency due to energy regeneration after the turn-off of power switches. The operational modes of the proposed topologies are verified by simulation and experimental results.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.75-76
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• 2016

Because of variable factors in construction phase, measurement of carbon emission in construction industry is more difficult than in other industries. To enhance accuracy of the measurement, the impact of variable factors must be considered. In this paper, to understand the influence of variable factors in steel erection work, a carbon emission casual map was developed. The map demonstrates that the considerations of variable factors in measurement of carbon emission improves the accuracy. The results of this paper are expected to contribute to development of carbon emission casual map and carbon emission measurement model for the entire construction phase.

• 대한전기학회논문지
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• 제33권4호
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• pp.127-133
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• 1984

In this paper the performance of a variable-phase thyristor motor combined with a phase splitter and a single-phase tapped induction motor is investigated. The phase splitter consists of a bridge type thyristor switching circuit. The regulating power flow of the phase splitter is obtained from the switching phase difference of thyristor switching sequences. The proper switching performance improves the torque-speed-characteristics of the motor and its operation efficiency. We simplify the motor system th using the tapped windng reactances of the motor as the complementary element of the thyristor phase splitter. We discussed the practicality of this motor system through the analysis of simulation result and the voltage and the current wave forms obtained froms obtained from the experiment.

• Journal of information and communication convergence engineering
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• 제6권3호
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• pp.285-288
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• 2008

Most of multimedia processors for 2D/3D graphics acceleration use a lot of integer/floating point arithmetic units. We present a new architecture with an efficient ALU, built in a smaller chip size. It reduces instruction cycles significantly based on a foundation of multi-thread operation, variable length instruction words, dual phase operation, and phase instruction's coordination. We can decrease the number of instruction cycles up to 50%, and can achieve twice better performance.