• 한국언론정보학보
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• 제26권
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• pp.7-44
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• 2004

이 논문은 영화에서의 시간성 표현 과정에 대한 기호학적 모델을 구성하기 위해 작성된 것이다. 연구자는 영화의 시간성 표현과 관련된 기존 서사 이론의 한계를 지적하고 이에 대한 대안으로서 들뢰즈(Gille Deleuze) 영화 철학(philosophy of cinema)의 적절성을 논의했다. 들뢰즈 영화 철학은 퍼스(Charles S. Peirce)의 삼원론적 기호학을 영화에 가장 잘 적용시킨 것으로 평가될 수 있는데, 이에 따라 연구자는 우선 영화를 구성하는 기호학적 최소 단위로서의 "운동아미지" 개념을 논의한 다음 이를 기반으로 고전적 서사 영화(classic narrative cinema)와 현대 영화(modern cinema)에서 나타나는 두 가지 서로 다른 시간성 표현의 기호화 과정을 비교했다. 즉, 고전적 서사 영화에서는 "정상적인 운동이미지"가 "간접적 시간 표현"과 "이야기-서사"라는 해석체를 구성하는 기호화 과정을 거치는 반면, 현대 영화에서는 "비정상적 운동이미지"가 "직접적시간 표현"과 "시간-이미지"라는 해석차를 구성하는 또 다른 기호화 과정을 거치는 것으로 보았다. 현대 영화의 기호학 과정에서 출현하고 있는 이와 같은 "시간-이미지"는 영화와 현실 사이에 놓여진 "시간"이라는 철학적 대상을 통찰하게 만들고 기존의 가치관과 이데올로기의 상투성을 극복할 수 있게 만든다. 이러한 맥락에서 "비정상적인 운동이미지"룰 만들어 내는 현대적 영상 제작 작업은 단지 특이하고 새로운 영화적 표현을 구성하는 데에만 그치는 것이 아니라, 시간을 주요한 사유의 대상으로 취하고 새로운 철학적 사유를 하게 만드는 보다 근원적인 성격을 가질 수 있게 되는 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.533-536
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• 1999

We consider digital implementation problems of continuous-time controllers. In general, digital controllers use fixed point representation of number and of finite word length(FWL). Under these conditions, this paper investigates the closed-loop stability caused by three design constraints; (i) finite precision representation of the controller parameters, (ii) realization forms such as direct form, cascade form, and parallel form, and (iii) sampling time. We calculate the coefficient stability margins of both predesigned controllers and controller to be implemented. This method can be applied to determine the word length, realization structure, and sampling time so that remains the stability.

• 산업공학
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• 제14권1호
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• pp.95-105
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• 2001

Previous work measurement methods need much time and effort of time study analysts because they have to measure required time through direct observations. In this study, we propose a method which efficiently measures standard times without involvement of human analysts using digital image processing techniques. This method consists of two main steps: motion representation step and cycle segmentation step. In motion representation step, we first detect the motion of any object distinct from its background by differencing two consecutive images separated by a constant time interval. The images thus obtained then pass through an edge detector filter. Finally, the mean values of coordinates of significant pixels of the edge image are obtained. Through these processes, the motions of the observed worker are represented by two time series data of worker location in horizontal and vertical axes. In the second step, called the cycle segmentation step, we extract the frames which have maximum or minimum coordinates in one cycle and store them in a stack, and calculate each cycle time using these frames. In this step we also consider methods on how to detect work delays due to unexpected events such as operator's escapement from the work area, or interruptions. To condude, the experimental results show that the proposed method is very cost-effective and useful for measuring time standards for various work environment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.75-77
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• 1994

This paper presents a method of obtaining transmission network equivalents from the network's driving-point admittance characteristic. Proposed method is based on modal decomposition representation for the large-scale interconnected system. As a result, Norton-type of discrete-time filter model can be generated. It can reproduce the driving-point admittance characteristic of the network. Furthermore proposed model can be implemented into the EMTP in a direct manner. The simulation results with the full system representation and the developed equivalent system showed a good agreement.

• Wind and Structures
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• 제31권1호
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• pp.59-73
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• 2020

Wind fragility analysis (WFA) of concrete chimney is often executed disregarding temperature effects. But combined wind and temperature effect is the most critical limit state to define the safety of a chimney. Hence, in this study, WFA of a 70 m tall RC chimney for combined wind and temperature effects is explored. The wind force time-history is generated by spectral representation method. The safety of chimney is assessed considering limit states of stress failure in concrete and steel. A moving-least-squares method based dual response surface method (DRSM) procedure is proposed in WFA to alleviate huge computational time requirement by the conventional direct Monte Carlo simulation (MCS) approach. The DRSM captures the record-to-record variation of wind force time-histories and uncertainty in system parameters. The proposed DRSM approach yields fragility curves which are in close conformity with the most accurate direct MCS approach within substantially less computational time. In this regard, the error by the single-level RSM and least-squares method based DRSM can be easily noted. The WFA results indicate that over temperature difference of 150℃, the temperature stress is so pronounced that the probability of failure is very high even at 30 m/s wind speed. However, below 100℃, wind governs the design.

• 대한산업공학회지
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• 제31권4호
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• pp.303-315
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• 2005

In this paper we address a design problem for hub-and-spoke networks and then consider a capacitated hub locations problem with direct shipment (CHLPwD). We determine the location of hubs, the allocation of nodes to hubs, and direct shipment paths in the network, with the objective of minimizing the total cost in the network. In this paper, CHLPwD is formulated as 0-1 integer programming. We develop an evolutionary algorithm here to solve the large sized CHLPwD. To do this, we present the representation and the genetic operators suitable for the problem and propose a heuristic method for the allocation of nodes to hubs. To enhance the search capability, problem-specific information is used in our evolutionary algorithm. The proposed algorithm is compared with the heuristic method in terms of solution quality and computation time. The experimental results show that our algorithm can provide better solutions than the heuristic.

• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.26-32
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• 2006

This paper targets a direct and quantitative prediction of characteristics of unstable waves in a combustion chamber, which employs the governing equations derived in terms of amplification factors of flow variables. A freshly formulated nonlinear acoustic equation is obtained and the analysis of unsteady waves in a rocket engine is attempted. In the present formalism, perturbation method decomposes the variables into time-averaged part that can be obtained easily and accurately and time-varying part which is assumed to be harmonic. Excluding the use of conventional spatially sinusoidal eigenfunctions, a direct numerical solution of wave equation replaces the initial spatial distribution of standing waves and forms the nonlinear space-averaged terms. Amplification factor is also calculated independently by the time rate of changes of fluctuating variables, and is no longer an explicit function for compulsory representation. Employing only the numerical computation, major assumptions inevitably inherent, and in erroneous manner, in up to date analytical methods could be avoided. With two definitions of amplification factor, 1-D stable wave and 3-D unstable wave are examined, and clearly demonstrated the potentiality of a suggested theoretical-numerical method of combustion instability.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.59-71
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• 2005

In this paper we address a design problem for hub and spoke transportation networks and then consider a capacitated hub locations problem with direct shipment (CHLPwD). We determine the location of hubs, the allocation of nodes to hubs, and direct shipment paths in the network, with the objective of minimizing the total cost in the network. An evolutionary algorithm is developed here to solve the CHLPwD. To do this, we propose the representation and the genetic operators suitable for the problem and adopt a heuristic method for the allocation of nodes to hubs. To enhance the search capability, problem-specific information is used in our evolutionary algorithm. The proposed algorithm is compared with the heuristic method in terms of solution quality and computation time. The experimental results show that our algorithm can provide better solutions than the heuristic.

• 한국게임학회 논문지
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• 제10권1호
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• pp.135-146
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• 2010

방송과 영화 등에서의 영상 기술의 발전은 최근 3차원 입체 영상에 대한 관심을 증가시켜 왔다. 뿐만 아니라 2차원 영상의 한계로 인하여 3차원 콘텐츠에서의 입체 영상 표현 기술 개발이 시간이 지날수록 더욱 활발해지고 있다. 이는 단지 방송 분야에 국한되는 것이 아니라 의료, 교육 등 다양한 분야에서 폭넓게 접할 수 있도록 입체 영상 기술이 개발, 연구되고 있다. 하지만 입체감 표현에 있어 필요한 정교한 연출과 입체감 인지에 따른 피로감 발생 등의 이유로 예측 불허로 변화하는 게임과 같은 실시간 시스템에서 입체 영상 기술의 접목은 거의 이루어지지 않고 있다. 본 논문에서는 DirectX SDK 그래픽 파이프라인의 기하학적 구조를 바탕으로 입체감을 효율적으로 다룰 수 있고 상황에 따른 자동 시점 간격 조정을 통해 피로감을 해결하는 깊이감 조절 기법을 설계하였다. 이를 통해 입체 영상 기술이 접목된 게임 제작이 활발히 이루어질수 있는 새로운 대안을 제시해보고자 한다.

• Journal of Power Electronics
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• 제13권3호
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• pp.419-428
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• 2013

The modular multilevel cascade converter (MMCC) is a new family of multilevel power converters with modular realization and a cascaded pattern for submodules. The MMCC family can be classified by basic configurations and submodule types. One member of this family, the Hexverter, is configured as Double-Delta Full-Bridge (DDFB). It is a novel multilevel AC/AC converter with direct power conversion and comparatively fewer required components. It is appropriate for connecting two three-phase systems with different frequencies and driving an AC motor directly from a utility grid. This paper presents the dq model of a Hexverter with both of its AC systems by state-space representation, which then simplifies the continuous time-varying model into a periodic discrete time-invariant one. Then a generalized multivariable optimal control strategy for regulating the Hexverter's independent currents is developed. The resulting control structure can be adapted to other MMCCs and is flexible enough to include other control criterion while guaranteeing the original controller performance. The modeling method and control design are verified by simulation results.