• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.648-651
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• 2004

Biped robot has better mobility than other mobile robot, but it is hard to maintain balance during walking. In order to maintain balance, stability analysis is a key point for a biped robot. The zero moment point analysis has been used most in stability analysis. In this paper, we propose different method of stability analysis using wrench system. It is possible to generate a wrench system by applying a force along an axis in space and simultaneously applying a moment about the same axis. Wrench system is equivalent to a force and moment applied along the same axis. We compare the result of wrench system analysis with that of zero moment analysis in biped robot stability using simulation program.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.4
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• pp.64-72
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• 2004

In this paper, the dynamic stability of a hydraulic excavator using ZMP concept is considered. When a load is moved in an excavator based on automation, an excavator often loses the stability and falls over. This is because a dynamic element is not included in the moment equilibrium equation that is used in order to judge a reversal. Consequently, reversal distinction algorithm including all a static and a dynamic element along a load movement in crane work is necessary. Zero Moment Point(ZMP) is a point on the floor where the resultant moment of the gravity, the inertial force of the manipulator and the external force is zero. This study is going to interpret the reversal stability of the excavator to which is applied ZMP concept through simulation.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2812-2814
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• 2005

본 논문에서는 이족보행 로붓의 보행패턴의 한 가지 방법으로 무릎을 피고 걷는 stretch 보행 알고리즘을 제안한다. 이전의 보행 알고리즘은 무릎을 구부리고 걷는 것이 대부분이다. 일반적으로 사람들이 걸을 때는 무릎을 거의 피고 걷기 때문에 사람과 비슷한 보행을 위해서 자세보정 시 Zero Moment Point(ZMP)를 이용한 무릎관절을 피고 걷는 보행 알고리즘을 제안하고 이의 구현을 위한 실험 수행을 통해 그 성능을 평가한다. 로봇은 보행상태에서 몸이나 발의 위치, 각도 등에 대한 보정작업이 없다면, 이로 인해 로봇의 궤적에 오차가 발생하게 되고, 그 결과 불안정하고 부자연스러운 보행을 하게 된다. 이러한 불안정성을 ZMP를 이용하여 보정 할 수 있다.

• The Mathematical Education
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• v.25 no.3
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• pp.77-100
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• 1987

Let G : R$^n$${\times}$R\longrightarrowR$^n$ be defined by a Homotopy solving a system F($\chi$)=0 of nonlinear equations. For the vector v$\^$k/ with G'(u$\sub$k/)v$\^$k/=0, ∥v$\^$k/∥=1 where uk is one point in Zero Curve let u$\sub$0/$\^$k/=v$\^$k/＋$\tau$v$\^$k/ be the first prediction for the next point u$\^$k+1/, $\tau$$\in$(0, 1). When u$\sub$0/$\^$k/ approaching too losely to some unwanted point. to follow the Zero Curve may occur the returning or cycling. One lion for it is discussed and tile parametrizied Homotopy algorithm for solving F($\chi$)=0 with it been established. Also some theorems by means of the regular value have been discussed for Zero Curves of G(u)=0 and some theorems for algorithm have been obtained.

• Journal of The Korean Astronomical Society
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• v.50 no.1
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• pp.1-5
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• 2017

Like Hipparcos, Gaia is designed to give absolute parallaxes, independent of any astrophysical reference system. And indeed, Gaia's internal zero-point error for parallaxes is likely to be smaller than any individual parallax error. Nevertheless, due in part to mechanical issues of unknown origin, there are many astrophysical questions for which the parallax zero-point error ${\sigma}({\pi}_0)$ will be the fundamentally limiting constraint. These include the distance to the Large Magellanic Cloud and the Galactic Center. We show that by using the photometric parallax estimates for RR Lyrae stars (RRL) within 8kpc, via the ultra-precise infrared period-luminosity relation, one can independently determine a hyper-precise value for ${\pi}_0$. Despite their paucity relative to bright quasars, we show that RRL are competitive due to their order-of-magnitude improved parallax precision for each individual object relative to bright quasars. We show that this method is mathematically robust and well-approximated by analytic formulae over a wide range of relevant distances.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.3
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• pp.183-192
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• 2003

This paper presents the real-time implemented distance relay algorithm which the fault distance is estimated with only local terminal information. When a single-phase-to-earth fault on a two-parallel transmission line occurs, the reach accuracy of distance relay is considerably affected by the unknown variables which are fault resistance, fault current at the fault point and zero- sequence current of sound line The zero-sequence current of sound line is estimated by using the zero sequence voltage which is measured by relaying location Also. the fault resistance is removed at the Process of numerical formula expansion. Lastly, the fault current through a fault point is expressed as a function of the zero-sequence current of fault line, zero-sequence current of sound line, and line, and fault distance. Therefore, the fault phase voltage can be expressed as the quadratic equation of the fault distance. The solution of this Quadratic equation is obtained by using a coefficient of the modified quadratic equation instead of using the square root solution method. After tile accurate fault distance is estimated. the mote accurate impedance is measured by using such an information.

• Communications of the Korean Mathematical Society
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• v.20 no.4
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• pp.813-826
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• 2005

Regarding all particles at a fixed site as a cluster, the size of the largest cluster under the zero range invariant measures is well studied by Jeon et al.[5] for the case of density one. Here, the density of the finite zero-range process is given by the ratio between the number m of particles and the number n of sites. In this paper, we study the lower density case, i.e., the case m = o(n). Especially, when m ~ $n^{\beta}$,0 < ${\beta}$ < 1, we show that there is an interesting cutoff point around $\beta$ = 1/2.

• Communications for Statistical Applications and Methods
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• v.16 no.3
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• pp.487-493
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• 2009

We consider a multiple defaultable zero coupon bond. Assuming defaults occur according to a marked point process, we explain how to estimate the time-t discounted price of zero coupon bond by simulation. For the special case of a given specific random face value, we show that the real probability measure is the risk neutral probability measure. In this case the time-t discounted conditional price can be obtained by observing a single sample path upto the time t in the real world. Furthermore the time-t discounted price can be estimated by observing real situations or by simulation under the real probability measure.

• Environmental and Resource Economics Review
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• v.11 no.2
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• pp.321-333
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• 2002

Approximating bottled water consumption distribution is complicated by zero observations in the sample. To deal with the zero observations, a mixture model of bottled water consumption distributions is proposed and applied to allow a point mass at zero. The bottled water consumption distribution is specified as a mixture of two distributions, one with a point mass at zero and the other with full support on the positive half of the real line. The model is empirically verified for household bottled water consumption survey data. The mixture model can easily capture the common bimodality feature of the bottled water consumption distribution. In addition, when covariates were added to the model, it was found that the probability that a household has non-consumption significantly varies with some variables.

• Journal of the Korean Data and Information Science Society
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• v.14 no.4
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• pp.929-937
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• 2003

Kernel type estimations of discontinuity point at an unknown location in regression function or its derivatives have been developed. It is known that the discontinuity point estimator based on $Gasser-M\ddot{u}ller$ regression estimator with a one-sided kernel function which has a zero value at the point 0 makes a poor asymptotic behavior. Further, the asymptotic variance of $Gasser-M\ddot{u}ller$ regression estimator in the random design case is 1.5 times larger that the one in the corresponding fixed design case, while those two are identical for the local polynomial regression estimator. Although $Gasser-M\ddot{u}ller$ regression estimator with a one-sided kernel function which has a non-zero value at the point 0 for the modification is used, computer simulation show that this phenomenon is also appeared in the discontinuity point estimation.