• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1995년도 하계학술대회 논문집 B
• /
• pp.695-698
• /
• 1995

The shape and width of fuzzy membership function has an effect on performance of fuzzy controller. In this paper, fuzzy controller is proposed to improve the control performance of fuzzy controller. It has two fuzzy inference engine. The one is typical fuzzy inference engine, the other is proposed to infer optimal width of membership function in fuzzy controller from plant constant (K,T,L). To show the effectiveness of this fuzzy controller with double fuzzy inference engine, it is applied to plant (dead time + 1st order delay) with various plant constant.

• 물과 미래
• /
• 제23권1호
• /
• pp.89-98
• /
• 1990

유역 수문학에 있어서 하도망의 지형학적 특성을 하천유출해석에 적용시키는 방법을 지형학적 순간단위도를 이용해서 검토하였다. 유역의 지형학적 특성은 Shreve link분류법과 Kirkby가 제안한 거리함수를 이용하여 정량적으로 표현 하였다. 거리함수는 해석적으로 유도된 확률모델로서 Weibull분포를 사용하였으며, 분석대상유역에 대한 거리함수의 확률모델과 하도망으 구조적 특성 및 기타 지형인자등을 분석하였다.

• 대한전기학회논문지
• /
• 제40권12호
• /
• pp.1230-1241
• /
• 1991

Asymmetrical pulse width modulated(APWM) control technique for AC chopper is proposed which can improve the input power factor. The ideal switching function for the proposed technique is derived and its optimal slope to maintain the input power factor to unity is calculated. By digital simulation several characteristics are investigated theoretically and then compared with those of the conventional PWM and the phase angle control technique. In order to maintain the input power factor to unity the optimal slope and the average value of the ideal switching function are calculated. The experimental results show a good agreement with the calculated ones, which proves the feasibility of the proposed technique.

• 전력전자학회논문지
• /
• 제16권5호
• /
• pp.484-493
• /
• 2011

본 논문은 뉴로-퍼지 제어기를 이용한 최적의 퍼지 소속함수에 동조하는 다층 신경회로망을 사용한 성능이 개선된 MPPT 알고리즘을 제안한다. 퍼지 제어기의 성능은 퍼지규칙과 퍼지 소속함수의 폭의 영향을 받는다. 뉴로-퍼지 제어기는 신경망 학습을 통해 퍼지 소속함수의 최적 폭을 이용하기 때문에 기존 퍼지 제어기보다 우수한 응답특성을 갖는다. 실험과 시뮬레이션 결과를 통해 제안된 알고리즘의 우수한 제어특성을 확인한다.

• Nuclear Engineering and Technology
• /
• 제49권7호
• /
• pp.1423-1430
• /
• 2017

Detonation cell width is an important parameter in hydrogen explosion assessments. The experimental data on gas detonation are statistically analyzed to establish a universal method to numerically predict detonation cell widths. It is commonly understood that detonation cell width, ${\lambda}$, is highly correlated with the characteristic reaction zone width, ${\delta}$. Classical parametric regression methods were widely applied in earlier research to build an explicit semiempirical correlation for the ratio of ${\lambda}/{\delta}$. The obtained correlations formulate the dependency of the ratio ${\lambda}/{\delta}$ on a dimensionless effective chemical activation energy and a dimensionless temperature of the gas mixture. In this paper, support vector regression (SVR), which is based on nonparametric machine learning, is applied to achieve functions with better fitness to experimental data and more accurate predictions. Furthermore, a third parameter, dimensionless pressure, is considered as an additional independent variable. It is found that three-parameter SVR can significantly improve the performance of the fitting function. Meanwhile, SVR also provides better adaptability and the model functions can be easily renewed when experimental database is updated or new regression parameters are considered.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.204-204
• /
• 2012

Peierls instability and spin ordering of zigzag graphene nanoribbons (GNR) created on a fully hydrogenated graphene (graphane) are investigated as a function of their width using first-principles density-functional calculations within the generalized-gradient approximation. For the width containing a single zigzag C chain (N=1), we find the presence of a Peierls instability with a bond alternated structure. However, for width greater than N=1, the Peierls distortion is weakened or disappears because of the incommensurate feature of Fermi surface nesting due to the interaction of C chains. Instead, there exists the antiferromagnetic (AFM) spin ordering in which the edge states are ferromagnetically ordered but the two ferromagnetic (FM) edges are antiferromagnetically coupled with each other, showing that electron-lattice coupling and spin ordering in GNR are delicately competing at an extremely thin width of N=2. It is found that, as the width of GNR increases, the energy gain arising from spin ordering is enhanced, but the energy difference between the AFM and FM (where two edge states are ferromagnetically coupled with each other) orderings decreases.

• Current Research on Agriculture and Life Sciences
• /
• 제27권
• /
• pp.69-75
• /
• 2009

This research regard it as most meaningful to realize the importance of the hedgerow in cultivated areas functioning as a residual landscape element in rural landscape and set improvement guidelines through landscape character and value analysis to cope with landscape malfunction. The results of summary are as follows. 1) First of all, as a result of landscape character analysis of edge stripe in cultivated land in total of 7 case areas, for example, the edge stripe in cultivated land in case area 4 and 8 maintain the width of 10m and are assessed satisfactory in terms of vegetation development condition, appearance of living species, connectivity, buffer capacity and so on. Also, as a result of structural character of correlation analysis among items, the correlation coefficient between width and appearance of living species showed 0.941, the highest. Following are connectivity and appearance of living species and width and buffer capacity respectively: 0.841 and 0.740. 2) As a result of landscape character analysis of uncultivated stripe in total of 6 case areas, it is analyzed that case area 4 maintains the widest width as almost 4.5m average width and considered valuable as I degree in vegetation development condition, filtering, and connectivity. 3) As a result of problem analysis of uncultivated stripe, for example, case 3, 9, and 10 was analyzed that the width was below 1.25m which is too small to carry out the function of buffer and habitat for living creature, so minimum standard width was set between 4~5m through comprehensive analysis of character of each case area. Based on the result above landscape character, value and problem analysis, main improvement guidelines are set in terms of width, connectivity, filtering, and vegetation development, restrictive practices and so on.

• 천문학회지
• /
• 제48권6호
• /
• pp.325-331
• /
• 2015

We study an association between the duration of solar activity and characteristics of the latitude distribution of sunspots by means of center-of-latitude (COL) of sunspots observed during the period from 1878 to 2008 spanning solar cycles 12 to 23. We first calculate COL by taking the area-weighted mean latitude of sunspots for each calendar month to determine the latitudinal distribution of COL of sunspots appearing in the long and short cycles separately. The data set for the long solar cycles consists of the solar cycles 12, 13, 14, 20, and 23. The short solar cycles include the solar cycles 15, 16, 17, 18, 19, 21, and 22. We then fit a double Gaussian function to compare properties of the latitudinal distribution resulting from the two data sets. Our main findings are as follows: (1) The main component of the double Gaussian function does not show any significant change in the central position and in the full-width-at-half-maximum (FWHM), except in the amplitude. They are all centered at ~ 11° with FWHM of ~ 5°. (2) The secondary component of the double Gaussian function at higher latitudes seems to differ in that even though their width remains fixed at ~ 4°, their central position peaks at ~ 22.1° for the short cycles and at ~ 20.7° for the long cycles with quite small errors. (3) No significant correlation could be established between the duration of an individual cycle and the parameters of the double Gaussian. Finally, we conclude by briefly discussing the implications of these findings on the issue of the cycle 4 concerning a lost cycle.

• 전기의세계
• /
• 제23권2호
• /
• pp.55-61
• /
• 1974

Nature of magnetic creep phenomena in low coercive force films(Ni 80%-Fe 20%) in form of narrow channels imbedded in high coercive force films is studied in this work. Aluminium is evaporated on the hot glass substrate and eched free in the shape of narrow channels by photoetoetching method. then, Permalloy(Ni 80%, Fe 20%) is deposited on these Aluminium substrate under the uniform field of 30(Oe) to introduce anisotropy. Permalloy film on Al has a high coercive force and one on the substrate devoid of Al has how coercive force. Magnetic revers domain which is introduced at the end of channel grows under the a.c field in hard axis direction, in spite of very weak d.c field in easy axis direction. This creeping is investigated as a function of external fields and channel widths. Permalloy film thickness is 500.angs.-900.angs. and channel widths are 40, 51, 65, 81, 115.mu. respectively. Creeping increases as external field increases while it decreases with channel width decrease. Creep velocity in channels depends on the a.c field along hard axis, d.c field along easy axis and channel widths and its range is 1-10cm/sec in this experiment. From study of dependence of creep velocity on channel width, it can be concluded that creep velocity is expressed in form of v=v$_{0}$ exp .alpha.(H-H$_{0}$) where .alpha. is a function of a.c field along hard axis and H is driving d.c field along easy axis, H$_{0}$ is not a coercive force of film as usuall expected but the d.c threshold field along easy axis which is a function of channel width. This characteristic is also confirmed by the study of dependence of creep velocity upon easy axis field strength. Value of .alpha. obtained is 1.3-2.3cm/sec We depending upon film charactor, hard axis field strength and frequency.uency.

• 한국수산과학회지
• /
• 제36권5호
• /
• pp.528-534
• /
• 2003

The 2-D hydraulic experimental results for the submerged rubble-mound structure, we have been concerned with the slability/function characteristics of the structures by the effects of wave force, scour/deposition at the toe and the wave transmission ratio at the lee-side sea. So, to investigate the variation characteristics of the wave transmission ratio which depended on a geometrical structure of the submerged breakwater profiles, the critical conditions for the depth of submergence and crest width were obviously presented. In summary, the results lead us to the conclusion that the wave control capabilities of submerged breakwaters by the variation of the submergence depth is higher than about 4 times the degree at the efficiency than the that of crest width. The destruction of the covering block at the crest generated at the region which was located between the maximum and minimum damage curve, and it's maximum damage/failure station from the toe of the structure was $0.2\;L_s.$ As the wave transmission coefficient and the slope of the structure increase, the damage/failure ratio and the maximum scour depth at the toe was extended, respectively. When the maximum scour depth happened, the destruction of the covering block which was located at the toe generated at the front of the submerged rubble-mound breakwater. Finally, it was found from the results that the optimization of the structure may be obtained by the efficient decision of the submergence depth and crest width in the permissible range of the wave transmission ratio.