• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.5
• /
• pp.496-501
• /
• 2012

An equilibrium point of a WIP (Wheeled Inverted Pendulum) with changing its center of gravity is derived and validated by various numerical simulations. Generally, the WIP has two equilibrium points which are unstable and stable one. The unstable one is interested in this study. To keep the WIP over the unstable equilibrium point, the WIP is consistently being adjusted. A state feedback controller for the WIP needs a control reference for the equilibrium point. The control reference can be obtained by studying an equilibrium point of the WIP based on statics. By using Lagrange method, this study is deriving dynamic equations of the WIP both with and without changing its center of gravity. Various numerical simulations are carried out to show the validation of the equilibrium point.

• Proceedings of the KIEE Conference
• /
• 1998.11a
• /
• pp.220-222
• /
• 1998

This paper presents a method, which develops an ability of Zero-phase Overcurrent Relay. Zero-phase current is very useful factor of Fault decision in Protect Relaying system. Actually, the setting-point value of Designed Relay, using Zero-phase current, is fixed. So in the case of deciding fault, Fixed setting-point value is not suitable for changing Load. and cause errors in Distributions system. For solving this problem, This paper proposes the Changed setting point value Algorithm, which can be adaptive for changing Distributions system using Zero-phase current r.m.s. indexes. The results of simulation under Load changing and High impedance fault show that proposed algorithm is useful for changing Distributions system and decreasing errors.

• Journal of Korean society of Dental Hygiene
• /
• v.7 no.4
• /
• pp.395-403
• /
• 2007

The purpose of this study is to investigate the main factors that affect turnover of Dental Hygienists so that it leads to preventing high turnover and long-term service in their position. Data were obtained from 112 dental hygienists who are currently working for dental clinics from September 17th 2007 to October 16th 2007 via questionnaires. For this study, the demographic factors and unique characteristics of Dental Hygienists are considered as well as all the variables of statistic. The results derived from using SPSS 11.0 are as follows: 1. The average of job related factors is 2.55 point, the average of job satisfaction is 2.59 point, the average of salary related factor is 2.24 point and the average of changing their occupation is 2.85 point. 2. The difference between the factors related to age and changing their occupation shows the highest level on job related factors.(pM0.033) in the age between 26 and 30. 3. Dental Hygienists who are in their occupation for 6years to 9 years answer that salary would be the main reason to change their jobs. 4. For married dental hygienists, salary related factor is the main reason to make them change their occupation.(pM0.002)

• Journal of Acupuncture Research
• /
• v.21 no.3
• /
• pp.43-59
• /
• 2004

Objective : In Modern society, patients with facial nerve paralysis are increasing because of many factors - irregular life, cold, overwork and stress etc. We have troubles in presuming the prognosis, though how to diagnosis and examine facial nerve paralysis are many. Methods : A clinical study was done on 89 patients who were diagnosed and treated as facial nerve paralysis(Bell's palsy) from January 2001 to May 2003 at the Dep. of Acupuncture and Moxibustion, college of Oriental Medicine, Woo-suk University. We classified 89 patients as the Sasang(四象) constitution, contributing factor, season, age and existence of diabetes items and analyzed, as we would research differences of changing point-Period from on set of Bell's palsy to the day which the change begins to be seen at the face- and improvement -Period which Bell's palsy is improved from on set to H-B grade II. Results : 1. Among the Sasang constitution, Soeumin($10.67{\pm}3.77days$) were faster than other constitutions, but Soyangin($16.25{\pm}6.75days$) were slower than other constitutions in changing point. Taeumin($4.12{\pm}1.49weeks$) were shorter than other constitutions, but Soyangin($4.88{\pm}2.11weeks$) were longer than other constitutions in improvement. 2. Among contributing factors, overwork and stress group were slower than other contributing factors in changing point($13.95{\pm}6.52days$), and longer than others in improvement($4.67{\pm}1.87weeks$). 3. Changing point and improvement of season, age, and existence of diabetes had the difference of the average according to an each item, but they were not statistically significant. 4. In 89 patients with Bell's palsy, average changing-point was $13.11{\pm}5.99$(days) and average improvement was $4.47{\pm}1.82$(weeks). Their correlation was 0.687 and statistically significance(P<0.01), therefore we could decide that their relation is highly correlation.

• Proceedings of the KIPE Conference
• /
• 2003.11a
• /
• pp.234-237
• /
• 2003

As the maximum power operating point (MPOP) of photovoltaic (PV) power systems changes with changing atmospheric conditions, the efficiency of maximum power point tracking (MPPT) is important in PV power systems. Many MPPT techniques have been considered in the past, but techniques using microprocessors with appropriate MPPT algorithms are favored because of their flexibility and compatibility with different PV arrays. Although the efficiency of these MPPT algorithms is usually high, it drops noticeably in case of rapidly changing atmospheric conditions. In this paper, we proposed a new MPPT control method called improved perturb and observe method (ImP&O), anda simple voltage and current characteristic equation of a PV array for PV array simulator. Experimental results verify the accuracy and excellent performance of the proposed MPPT method. ImP&O algorithm is very simple, and has successful tracked the MPOP, even in case of rapidly changing atmospheric conditions.

• Journal of Korea Water Resources Association
• /
• v.43 no.7
• /
• pp.645-655
• /
• 2010

In this study, occurrences of relative probabilistic changing points between Chukwooki rainfall data (CWK) and modern rain gage data (MRG) were analyzed using Barry and Hartigan (BH) Bayesian changing points estimation method which estimated the changing points by calculation of change probabilities at each point. Since any natural phenomenon cannot be simulated identically and perfectly, a statistical method which can not consider the sequential order has its limitation on prediction of a specific time of occurrence. In this respect, Homogeneity analysis between CWK and MRG was performed through the occurrence investigation of relative probabilistic changing points for four rainfall characteristics of data sets using BH bayesian model which estimate the change point by calculating the relative probabilities in each data points. The results show that statistical characteristics of CWK are not different significantly from MRG, even though considered that there may be little quantitative difference CWK and MRG caused from limitation of measurement accuracy of CWK.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.5
• /
• pp.525-529
• /
• 2009

Most of FLC received input data from error e and change-of-error e' with no relation with system complexity. Basic scheme follows typical PD and PI or PID Controller and that has been developed through fixed ME In this paper, We studied the relationship between MF and system response and system response through changing Fuzzy variable of consequence MF and propose the simple FLC using this relationship. The response of FLC is changed according to the width of Fuzzy variable of consequence MF. As changing the Fuzzy variable of consequence MF shows various nonlinear characteristic, we studied the relation between response and MF using analytical method. We designed the effective FLC using three-variable MF and nine rules and took simulation for verification. In this study, we propose the method to design system with FLC in stability point which is an impotent characteristic of designing system. The circle criterion which is adapted to analysis the nonlinear system is put to use for proposed method. Since SISO FLC has a time-invariant and odd characteristic we can use the critical point not disk which is generally used to determine the stability in the circle criterion, to determine the stability. Using this, we can get the maximum critical point plot of SISO FLC with changing the consequence fuzzy variables. The predetermined critical point plot of FLC can be used to decide the region of the system to be stable. This method is effectively used to design the SISO FLC.

• Bulletin of the Korean Mathematical Society
• /
• v.47 no.2
• /
• pp.411-422
• /
• 2010

By using the fixed point index theory, we investigate the existence of at least two positive solutions for p-Laplace equation with sign-changing nonlinear terms $(\varphi_p(u'))'+a(t)f(t,u(t),u'(t))=0$, subject to some boundary conditions. As an application, we also give an example to illustrate our results.

• Journal of Power Electronics
• /
• v.10 no.5
• /
• pp.528-537
• /
• 2010

A novel decision reference based method for the maximum power point tracking (MPPT) of PV arrays is presented in this paper. The proposed decision reference was derived from a simplified solar cell model. This method solves the problems of conventional MPPT algorithms, such as oscillation of the operating point at the steady state and confusion under rapidly changing insolation. It is shown by simulation and experimental results that the method properly tracks a rapidly changing insolation profile. The signal to noise ratio (SNR) of the new decision reference is also higher than those of conventional P&O and INC methods. An updating subroutine was included in the proposed MPPT algorithm to compensate for temperature and aging effects.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.3
• /
• pp.133-141
• /
• 2002

Most maximum power point tracking(MPPT) control algorithm is based on Perturb and Observe(P&O) and Incremental Conductance(IncCond). In comparison with P&O and IncCond algorithm, the dynamic and tracking characteristic of IncCond algorithm is better than P&O algorithm in condition of rapidly changing solar radiation. But in the case of digital implementation, the InCond algorithm has error en decision of maximum power operation point(MPOP). To solve this problem, this paper proposes a improved IncCond algorithm, which can determine the MPOP correctly by inserting the test signal in control input. This paper proposes a novel MPPT control algorithm for the digitally implemented photovoltaic system in condition of rapidly changing solar radiation. To verify the validity of the proposed control algorithm. the computer simulation and experiment are carried out.