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- 검색키워드
- 저자 : 李相卨 (검색결과 376 건)
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이상설,안도만,강희정 한국산업경영시스템학회 1999 한국산업경영시스템학회지 Vol.22 No.49
The objective of this study is to develop an improved algorithm for layout problems. Computerized facility layout program was also applied to solve the layout problem in locomotive maintenance workshop. The current facility layout is structured in the large space without considerations of many variable factors. For this reason, effectiveness of layout results in loss on effective space utility. This study is to develop an algorithm in the consideration of importance weight and desirable shape of specific department in the computerized layout planning and quantitative relationship rating between each department was used. Standard process duration of locomotive maintenance workshop was used to select the main activities of locomotive maintenance work. This study could generate more efficient facility layout design to reduce the number of movement frequency and travel distance in maintenance workshop.
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이상설 光云大學校 1974 論文集 Vol.3 No.-
Recently, the snaked-line antenna is used widely for the X-band radar systems. The radiation characteristics of the linear antennas are well known and can be predicted from the magnetic vector potential for an assumed current distribution. However, little is known about the behavior of the arbitary-shaped bent antennas, except for the U-shaped antenna developed by Montgomery. The radiation characteristics of bent-wire antennas have been shown by experimental measurements. This work is carried to find the current distribution of a bent-wire element by the moment method and then to derive the general expressions of the retarded vector potential, the resulting complex field and Poynting vectors in the far zone. Since the snaked-line antenna is composed of several bent-wire elements of the same form, this work is a part of the analysis of the snaked-line antenna. For the antenna which is bent-y-z plane of rectangular coordinates, its current vector can be expressed by the function representing its wire shape, and the Poynting vector from the current can be obtained. In equation L(f)=g, when L is a linear operator, its solution f can be expanded by the basic functions f₁,f₂......If scalar product is taken to the equation by the weighting functions ω₁, ω₂.....it can be transformed to the matrix relation and its solution is found. The matrix dimension of the equation and the accuracy of its solution depend on the choice of basic functions and weighting functions. By the properties of linear space, basic functions and weighting functions must be linearly independent. The bent-wire antenna is considered as N shout sigments connected together. The end points of each segment define a pair of terminals. These terminals can be thought of as forming an N-port network, and the wire antenna is obtained by short-circuiting all ports of the network. One can determine the impedance matrix for the N-port network. The impedance matrix elements can be determined by the current and the voltage relations, when applying the current to one segment, the voltage induced by the current to the other port which is open circuited is measured. If the admittance matrix which is the inverse of the impedance matrix is known, by applying voltage to any port the port current matrix (current distribution on the wire) can be found by the voltage and admittance matrix multiplication. From the solution of an integral equation for the charge and current induced on a conducting body by the impressed field, elements of the impedance matrix is obtained. Integrals are approximated by the sum of integrals over N small segments, obtained by treating its current and charges as constants over each segment. Derivatives are approximated by finite differences over the same intervals used for integration. Since in antennas, the voltage source is applied only on the feeding point, the voltage matrix is transformed to a column matrix which has zero elements except the feeding point element. Since the current is computed by the relation (I)=(Y)(V), for the unit voltage source, the current matrix is the column of admittance matrix which has the same column number as the feeding point number. And nth diagonal element of the admittance matrix is the input admittance of the antenna which is fed at nth element. By the above method, the input impedance and radiation patterns of sinusoidal-shaped dipole antenna were computed by an IBM 360/40 computer which had a core memory capacity of 63K. When an image pane which is large compared with the antenna length is placed behind the antenna, by the image theory, the resultant radiation patterns are identical to be 2-element array pattern. The antenna; the diameter of its conductor 1.0mm, the length of end to end 10cm, the undulation amplitude 4cm, was used for measurements, and an alminium plate; its size 92 × 92cm², its thickness 1.5mm, was used as the image plane. The antenna impedance was measured by the parallel-plate slotted section coaxial standing wave detector and its radiation patterns were measured by the fixed detecting antenna which detected the radiation power radiated form the antenna rotating on the pattern measuring table. The results of the measurements is inconsistent with the theoretical results. For the sinusoidal-shaped dipole antenna, its radiation pattern for ø=0 plane is broader than the linear dipole antenna, but for θ=π/2 plane directivity is higher than dipole. Its impedance characteristics show that the resonance frequency of he sinusoidal-shaped dipole antenna is different from that of the linear dipole antenna with the same length. Since in this method, the antenna is considered of the sets of small segments, this method can be applicable to the antenna of which shape not represented by the continuous function, for example, the rectangular form, triangular form. etc. In this work, the radiation properties of a part of the snaked-line antenna is analysed. This method of analysis is can be extended to snaked-line antenna if its travelingwave terms are considered.
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