• 전기학회논문지
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• 제59권7호
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• pp.1295-1301
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• 2010

In this note, a systematic general design of a new robust nonlinear variable structure controller based on state dependent nonlinear form is presented for the control of uncertain affine nonlinear systems with mismatched uncertainties and mismatched disturbance. After an affine uncertain nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a new robust nonlinear variable structure controller is presented. To be linear in the closed loop resultant dynamics, the nonlinear integral-type sliding surface is applied. A corresponding control input is proposed to satisfy the closed loop exponential stability and the existence condition of the sliding mode on the nonlinear integral-type sliding surface, which will be investigated in Theorem 1. Through a design example and simulation studies, the usefulness of the proposed controller is verified.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
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• pp.206-211
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• 2005

The LC filter design procedure of the inverter output filter is described. The transfer function of the filter output voltage to the load current is described with the capacitor value and the system time constant considering the system controller. By using the closed form of the relation between the filter capacitor value and the system time constant, the capacitor value can be calculated with the given system time constant and vice versa. It is more practical for the implementation of power and control circuit of inverter. And as the effect of the load current to the voltage distortion can be calculated from the closed form, it is possible to analyze the system how much the voltage waveform is distorted in case of the nonlinear load. All the proposed design procedure is verified with the simulation and experimental results.

• 복합신소재구조학회 논문집
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• 제5권2호
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• pp.1-8
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• 2014

Fiber reinforced polymeric plastic (FRP) materials have many advantages over conventional structural materials, i.e., high specific strength and stiffness, high corrosion resistance, right weight, etc. Among the various manufacturing methods, pultrusion process is one of the best choices for the mass production of structural plastic members. Since the major reinforcing fibers are placed along the axial direction of the member, this material is usually considered as an orthotropic material. However, pultruded FRP (PFRP) structural members have low modulus of elasticity and are composed of orthotropic thin plate components the members are prone to buckle. Therefore, stability is an important issue in the design of the pultruded FRP structural members. Many researchers have conducted related studies to publish the design method of FRP structures and recently, referred to the previous researches, pre-standard for LRFD of pultruded FRP structures is presented. In this paper, the accuracy and suitability of design equation for the local buckling strength of pultruded FRP I-shape compression members presented by ASCE are estimated. In the estimation, we compared the results obtained by design equation, closed-form solution, and experiments conducted by previous researches.

• 한국의류학회지
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• 제29권12호
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• pp.1582-1594
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• 2005

이 연구의 목적은 패션디자인에서의 형태의 중요성을 이해하는 새로운 시각을 제시하는데 있다. 뵐플린과 드롱의 이론을 바탕으로 Flat St Rounded, Closed & Opened 과 Part & Whole의 세 가지 형태를 보는 시각을 가지고 Vionnet와 Dior 작품에서의 형태미를 분석하는데 적용시켜 고찰해 보았다. Vonnet와 Dior은 그들의 디자인에서 형태와 구조를 디자인의 기본원리로 하여 기하학적인 형태를 그들의 디자인에 적용시킨 디자이너들이다. Vionnet의 10작품과 Dior의 11작품을 선정해 Belong의 visual priorities diagram을 적용시켜 각 디자이너 작품의 형태미를 고찰하고 비교해 보았다. Vionnet는 의복과 인간의 신체 사이의 관계를 통해 새로운 형태미학을 창조해 냈으며 그녀의 작품은 2차원 또는 3차원이라는 공간의 차이에 따라 형태의 전위를 보여주는 독특한 형태학적 특성을 보여주고 있다 그녀의 작품은 2차원의 공간에서는 평면적이고 닫힌 형태인 삼각형, 사각형, 원으로 구성되어 있으나 바이어스 재단에 의한 입체재단 방법을 통해 3차원의 공간에서는 입체적이고 열린 형태로의 형태변형을 한다는 특징을 나타낸다. Dior의 작품은 인체의 자연스러운 형태보다는 인위적인 형태미를 보여주고 있으며 이는 Vionnet작품과의 커다란 차이점이다. Dior은 3차원의 공간에서 구, 각기둥, 원기둥, 각뿔, 입방체와 같은 입체 기하학의 형태를 사용하여 의복의 형태를 만들어 냈고 이는 다아트 변형, 보닝, 개더, 턱, 플리츠, 셔링과 같은 구조주의적인 기술을 통해 실현되고 있다. Dior의 작품은 3차원의 공간에서 인체의 형태와는 무관한 의복 자체만의 형태를 가지고 있으며 이는 입체적이고 닫힌 형태적 특성을 가진다.

• 한국정밀공학회지
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• 제26권2호
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• pp.35-44
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• 2009

Long stroke Fast Tool Servo (LFTS) with maximum stroke of $432{\mu}m$ is designed, manufactured and tested for fabrication of optical free-form surfaces. The large amount of stroke in LFTS has been realized by utilizing the hinge and lever mechanisms which enable the displacement amplification ratio of 4.3. In this mechanism the peculiar shape was devised for maximizing the displacement of end tip in LFTS and special mechanical spring has been mounted to provide the sufficient preload to the piezoelectric actuator. Also, its longitudinal motion of tool tip can be measured by capacitive type displacement sensor and closed-loop controlled to overcome the nonlinear hysteresis. In order to verify the static and dynamic characteristics of designed LFTS, several features including step response, frequency response and cut-off frequency in closed-loop mode were experimentally examined. Also, basic machining result shows that the proposed LFTS is capable of generating the optical free-form surface as an additional axis in diamond turning machine.

• 대한전기학회논문지:전력기술부문A
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• 제48권5호
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• pp.586-592
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• 1999

We investigate the characteristic of 소데 responses of the Manabe standard form which is used recently for design of the controller. We obtain some theorems and these theorems have the properties of the relationship between the roots of the polynomial and the stability indices which are used for the Manabe standard form. The Manabe standard form has the following properties: The sum of the squal to zero, the sum of the reciprocal of the squared roots is greater than zero and the parameter $\tau$ is the negative value of the sum of the reciprocal of the roots. We compare the step responses of the Manabe standard form with those of the ITAE form, the dead beat response and Bessel forms. We choose the 6th order closed loop polynomial and keep the same settling time for the four forms. Under these conditions we find that the Manabe standard form have faster 90% rising time than the Bessel and dead beat response. We see that the ITAE, bessel and dead beat responses have some overshoot, whereas the Manabe standard form has none. We also compare the Manabe form with the other three forms for the controller design using the pole assignment technique. If the open loop transfer function is a type-1 system (transfer functions having one integrator), then, for the closed loop system associated with the open loop transfer function, the steady state error of the unit ramp input is obtained in terms of the parameter $\tau$ of the Manabe standard form.

• 복식
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• 제58권7호
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• pp.76-91
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• 2008

The purpose of this study is to prescribe formative perspectives as a framework where the aesthetic taste and demands of a certain period are embodied and to develop new analytical tools to examine the beauty of dress in terms of form. First, the theoretical tools selected for this study are Heinrich Wolfflin's formative perspective theory derived from art and Marilyn R. DeLong's framework for visual analysis of dress. Second, several issues that limited the development of a new framework for analyzing the form of dress were identified and addressed. Third, the selected aspects of dress form to be analyzed are specified. They are: silhouette, inner form, structure form, materials and patterns based upon the relationship between the body, dress and space in order to develop new formative perspectives. Based upon these theories a new framework for analyzing dress aesthetics in terms of form is developed. This reconstructed framework consists of three sets of antagonistic representational styles: closed form/open form, linear form/painterly form and multiplicity/unity. Closed form/open form represented in dress can be classified by the clear or obscure silhouette shown not only in the relationship between the dress and space around the dress, but also from changeability or invariability of dress in relation to the body. The material, pattern and various design elements are used as the central criteria to determine the linear/painterly characteristics in dress representations. Finally, the multiplicity/unity can be found in the relationship between the whole and the parts. Multiplicity is represented in dress when the parts have a visual priority over the whole, whereas unity is represented when a dress as a whole has visual priority over the parts. A dress represented with closed form, linear characteristic and multiplicity is perceived as a clear form. In contrast, a dress with open form, painterly characteristic and unity is understood to be an obscure form. It can be said that this study is the first attempt to establish the formative perspectives for analyzing the form of dress in various periods, cultures and races for the future studies.

• 전기학회논문지
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• 제59권8호
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• pp.1406-1415
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• 2010

As process technology for semiconductor goes beyond the ultra-deep submicrometer regime, interconnect reliability on a chip has become a serious design concern. As process parameters scale, interconnect widths are reduced rapidly while the current flowing through the interconnect does not decrease in a proportional manner. This trend increases current densities in metal interconnects which may lead to poor reliability for electromigration. Hence, it is critical to estimate the current amount passing through the interconnects earlier in semiconductor design stages. The purpose of this paper is to propose a fast yet accurate current estimation technique that can offer not only analysis time equivalent to those offered by the previous approximation methods but also a relatively precise estimation by using closed-form equations. The accuracy of the proposed technique was confirmed to be about 8 times better on average when compared to the previous work.

• International Journal of Control, Automation, and Systems
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• 제5권2호
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• pp.138-146
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• 2007

The analysis and design method for achieving robust stabilization of Decentralized Dynamic Surface Control (DDSC) is presented for a class of interconnected nonlinear systems. While a centralized design approach of DSC was developed in [1], the decentralized approach to deal with large-scale interconnected systems is proposed under the assumption that interconnected functions among subsystems are unknown but bounded. To provide a closed-loop form with provable stability properties, augmented error dynamics for N nonlinear subsystems with DDSC are derived. Then, the reachable set for errors of the closed-loop systems will be approximated numerically in the form of an ellipsoid in the framework of convex optimization. Finally, a numerical algorithm to calculate the $L_2$ gain of the augmented error dynamics is presented.

• 한국조경학회지
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• 제25권2호
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• pp.104.1-104.1
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• 1997

The purpose of this study is to grasp the characteristics of user''''s response to perceived safety and visual preferences for outdoor green spaces by the types of campus layouts. This research was investigated by color slide ratings and questionnaire survey to the students who are majoring in Landscape architecture in three universities locating at Taegu area. Two research sites have similarities in many ways but have differences in campus land form and design type such as ''''Closed'''' and ''''Open'''' types. Major results were summarised as follows ; 1. As a result of the slide test, the high degree of visual preference was shown in the campus that is ''''Closed'''' type. However the degree of perceived safety was lower than that of in Youngnam Univ. campus. 2. According to the result of the comparative analysis between user''''s perceived safety and visual preferences in each campus, the degree of perceived safety at ''''Closed'''' type was lower than that of ''''Open'''' type, but the degree of visual satisfactioni was higher at ''''Closed'''' type. 3. The factors affecting visual preference in campus were shown as density of wood, land form, and diverse type of the spaces. On the other hand, the factors affecting perceived safety were ''''enclosed space by wood'''' at the day time, and ''''the condition of lighting'''' at night. 4. Regarding gender differences in sensation of each space variables, female users showed higher satisfactio on the scenic beauty. 5. Regression analysis showed that general satisfation was determined by the variables such as ''''arrangement'''', familiarity'''', ''''cleanness'''', and ''''closed feeling'''', in Kyungbook Univ. And in Youngnam Univ. , the variables were ''''texture'''', ''''perceived beauty'''', ''''cleanness'''', and ''''complexity'''' respectively. 6. In conclusion, campus users wanted the outdoor spaces that have various land form and somewhat ''''open-closed'''' mixture type, which has a good ''''Edge Effect'''' to satisfy both aspects in safety and visual preferneces.