• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.647-652
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• 2008

This paper focused on the application of finite element model updating technique to evaluate the structural properties of the reinforced concrete specimen using the data collected from shaking table tests. The specimen was subjected to six El Centro(NS, 1942) ground motion histories with different Peak Ground Acceleration(PGA) ranging from 0.06g to 0.50g. For model updating, flexural stiffness values of structural members(walls and slabs) were chosen as the updating parameters so that the converged results have direct physical interpretations. Initial values for finite element model were determined from the member dimensions and material properties. Frequency response functions(i.e. transfer functions), natural frequencies and mode shapes were obtained using the acceleration measurement at each floor and given ground acceleration history. The weighting factors were used to account for the relative confidence in different types of inputs for updating(i.e. transfer function and natural frequencies). The constraints based on upper/lower bound of parameters and sensitivity-based constraints were implemented to the updating procedure in this study using standard bounded variable least-squares(BVLS) method. The veracity of the updated finite element model was investigated by comparing the predicted and measured responses. The results indicated that the updated model replicates the dynamic behavior of the specimens reasonably well. At each stage of shaking, severity of damage that results from cracking of the reinforced concrete member was quantified from the updated parameters(i.e. flexural stiffness values).

• 한국소음진동공학회논문집
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• 제18권7호
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• pp.725-731
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• 2008

This paper focused on the application of finite element model updating technique to evaluate the structural properties of the reinforced concrete specimen using the data collected from shaking table tests. The specimen was subjected to six El Centre (NS, 1942) ground motion histories with different peak ground acceleration (PGA) ranging from 0.06 g to 0.50 g. For model updating, flexural stiffness values of structural members (walls and slabs) were chosen as the updating parameters so that the converged results have direct physical interpretations. Initial values for finite element model were determined from the member dimensions and material properties. Frequency response functions (i.e. transfer functions), natural frequencies and mode shapes were obtained using the acceleration measurement at each floor and given ground acceleration history. The weighting factors were used to account for the relative confidence in different types of Inputs for updating (j.e. transfer function and natural frequencies) The constraints based on upper/lower bound of parameters and sensitivity-based constraints were implemented to the updating procedure in this study using standard bounded variable least-squares(BVLS) method. The veracity of the updated finite element model was investigated by comparing the predicted and measured responses. The results indicated that the updated model replicates the dynamic behavior of the specimens reasonably well. At each stage of shaking, severity of damage that results from cracking of the reinforced concrete member was quantified from the updated parameters (i.e. flexural stiffness values).

• Journal of Radiation Protection and Research
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• 제25권1호
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• pp.11-19
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• 2000

동적섭식경로모델 DYNACON에 대한 입력변수의 민감도 분석을 장반감기 핵종 $(^{137}Cs,\;^{90}Sr)$에 대해 침적시점의 함수로 평가하였다. 또한 장, 단기간 음식물 (곡류, 엽채류, 우유) 오염에 대한 입력변수의 영향이 고찰되었다. 입력변수는 LHS 기법으로 표본 추출되었으며, 민감도 지수는 PRCC로 나타냈다. 핵종과 음식물의 종류에 따른 민감도 지수는 침적시점 뿐 아니라 장, 단기간 오염에 있어서도 뚜렷이 다르게 나타났다. 작물의 성장기 침적의 경우 장, 단기간 오염 모두 잎흡수에 의한 오염 관련변수가 중요하였다. 또한 작물의 비성장기 침적의 경우 단기간 오염에 있어서도 잎흡수에 의한 오염 관련변수가 중요하였다. 장기간 오염의 경우 잎흡수에 의한 오염 관련변수의 영향은 줄고 뿌리흡수에 의한 오염 관련변수의 영향이 증가하였다. 특히 이러한 현상은 작물의 성장기 침적에 비해 비성장기 침적의 경우에, $^{l37}Cs$ 침적에 비해 $^{90}Sr$ 침적의 경우에 보다 뚜렷하였다. 목초의 성장기 침적의 경우 우유로의 핵종 전달계수, 젖소의 일일 목초 섭취량과 같은 가축 특성 관련변수가 상대적으로 우유의 오염에 중요한 입력변수로 나타났다.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2007년도 춘계학술대회 논문집
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• pp.231-236
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• 2007

The aspects of contemporary society change have been changed rapidly running for function value on the part of part industrialization and information-oriented. The transfer to the society focused on a human being emphasis and symbol value is in progress rising with natural desire of recurrence of human nature accordingly and desires of a human being inborn of sensitivity-oriented and pluralism-oriented are being expressed. Answering these social and cultural demands, concerns about an arbitrary mind world of a human being and pursuit dispositions about impractical and transcendental world are coincided with to the purpose and so various kinds of expressions except for art sphere are being experimented and applied. Here upon also in the field of the contemporary interior design, answering sensual desire of users, various arts and cultural tendency, the concept of surrealism is being applied in design introducing the concept of surrealism positive. And fantastical and unreasonable expression features of surrealism are being used as subjective essential elements to make new spaces. Especially amoung various kinds of the interiors designs, the features like surrealistic expressions in Food & Beverage Space which proper identity and strong symbolism will be expressed can be recognized as appropriate expression patterns to give still more sensitivity stimuli to customers. Thus this research disclosed conceptual and ideological background of surrealism and also analyzed and studied surrealistic expression features applied to the interiors designs of Contemporary Food & Beverage Space through expression disposition, study and classification of techniques. And standing on the result of analyzing surrealistic expression features of Contemporary Food & Beverage Space with a key word of expression features derived we groped for estatescape trend demanded in Food & Beverage Space and direction coming.

• 대한전자공학회논문지
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• 제26권7호
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• pp.112-124
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• 1989

최근 본 연구팀에서 기존의 선 조사방식 디지탈 X-선 촬영시스템의 단점을 보완하여 촬영시간을 0.7초로 단축시키고 환자에의 X-선 조사량을 3mR 정도로 감소시킨 디지탈 X-선 촬영시스템을 개발한 바, 이 논문에서는 이 시스템의 감도 특성, 산란 성분 구성률, 양자검출 효율, 변조전달함수, 그리고 콘트라스트 상세도 등과 같은 물리적 및 영상특성들을 조사함으로써 그 촬영성능을 평가하였다. 조사 결과 이 시스템의 감도특성은 입사에너지에 비례하며, 기존의 필름-스크린 보다 적은 X-선 조사량으로도 더 우수한 콘트라스트 해상도를 지녔음이 나타났다. 그 이유는 뛰어난 산란선 제거능력과 양자검출 효율 때문인 것으로 생각된다.

• 대한기계학회논문집A
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• 제21권5호
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• pp.819-827
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• 1997

In this paper, a new modeling of a fine actuator for an optical pick-up has been proposed and multiobjective optimization of the actuator has been performed. The fine actuator is constituted of the bobbin which is supported by wire suspension, the coils which wind around the bobbin, and the magnets which cause the magnetic flux. If current flows in the coils, magnetic force is so produced as to be balanced with spring force of wire, so the bobbin is pisitioned. In this model the transfer function from input voltage to output displacementof bobbin has been obtained so that we can describe this integrated system with electromagnetic and mechanical parts. Wire suspension is regarded as a continuous Euler beam, damper as distributed viscous damping, and bobbin as a rigid body which can move up- and down- ward motion only. According to the model, the high frequency dynamic characteristics of the fine actuator can be known and the effect of damping can be investigated while the conventional second order model cannot. In multiobjective optimization, two objective functions have been chosen to maximize the fundamental frequency and the sensitivity with respect to the input voltage of the actuator so that Pareto's optimal solutions have been obtained using .epsilon.-constraint method. These objective functions will satisfy the trends which will enhance the access speed and reduce the tracking error in the optical pick-up technology of next generation. In the result of optimization, we obtain the designs of the optical pick-up fine actuator which has high speed, high sensitivity and low resonant peak. Furthermore, we offer the relation between two object functions so that the designer can make easy choice.

• 비파괴검사학회지
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• 제34권1호
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• pp.38-43
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• 2014

굽힘파 전파 특성을 이용하여 지지강성을 도출하고 이를 이용한 레일체결장치의 결함 검출 시험법을 제안하였다. 점탄성 패드로 지지되고 체결장치로 고정된 레일의 진동 응답은 주파수에 따라 지지단 동특성에 크게 영향을 받는다. 체결장치에 결함이 발생할 경우에는 구조적인 불연속성으로 인해 굽힘 파동의 전파 특성이 변화하게 된다. 이러한 변화를 감지하기 위해서 전달함수법을 이용해 주파수에 따라 변화하는 레일 지지단 동특성을 측정하였다. 연속 스프링으로 지지된 레일 응답으로부터 예측한 레일의 보존에너지를 이용해 결함에 대한 파동 전파의 민감도를 해석하였다. 민감도 해석 결과와 동적지지강성 변화를 측정하여 손상지수를 계산하고 결함 위치를 추정하였다.

• Journal of the Optical Society of Korea
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• 제18권3호
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• pp.256-260
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• 2014

Columnar-structured cesium iodide (CsI) scintillators doped with thallium (Tl) are frequently used as x-ray converters in medical and industrial imaging. In this study we investigated the imaging characteristics of CsI:Tl films with various reflective layers-aluminum (Al), chromium (Cr), and titanium dioxide ($TiO_2$) powder-coated on glass substrates. We used two effusion-cell sources in a thermal evaporator system to fabricate CsI:Tl films on substrates. The scintillators were observed via scanning electron microscopy (SEM), and scintillation characteristics were evaluated on the basis of the emission spectrum, light output, light response to x-ray dose, modulation transfer function (MTF), and x-ray images. Compared to control films without a reflective layer, CsI:Tl films with reflective layers showed better sensitivity and light collection efficiency, and the film with a $TiO_2$ reflective layer showed the best properties.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.433-437
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• 2003

Quantitative Feedback Theory (QFT) is one of effective methods of robust controller design. In QFT design we can considers the phase information of the perturbed plant so it is less conservative than $H_{\infty}$ and ${\mu}$-synthesis methods and as be shown, it is more transparent than the sensitivity reduction methods mentioned . In this paper we want to overcome the major drawback of QFT method which is lack of an automatic method for loop-shaping step of the method so we focus on the following problem: Given a nominal plant and QFT bounds, synthesize a controller that achieves closed-loop stability and satisfies the QFT boundaries. The usual approach to this problem involves loop-shaping in the frequency domain by manipulating the poles and zeros of the nominal loop transfer function. This process now aided by recently developed computer aided design tools proceeds by trial and error and its success often depends heavily on the experience of the loop-shaper. Thus for the novice and First time QFT user, there is a genuine need for an automatic loop-shaping tool to generate a first-cut solution. Clearly such an automatic process must involve some sort of optimization, and while recent results on convex optimization have found fruitful applications in other areas of control theory we have tried to use LMI theory for automating the loop-shaping step of QFT design.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.452-457
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• 2003

An add-on type output regulator is proposed in this paper. By an add-on controller we mean an additional controller which operates harmonically with a pre-designed one. The role of the add-on controller is to reject a sinusoidal disturbance of unknown magnitude and phase but with known frequency. Advantages of the proposed controller include that (1) it can be used only when the performance of disturbance rejection needs to be enhanced, (2) when it is turned on or off, unwanted transient can be avoided (i.e., bumpless transfer), (3) it is designed for perfect disturbance rejection not just for disturbance reduction, (4) ability for perfect rejection is preserved even with uncertain plant model. This design may be promising for optical disc drive (ODD) systems in which disc eccentricity results in a sinusoidal disturbance. For ODD systems, the sensitivity function obtained by the pre-designed controller, which may have been designed by the lead-lag, $H_{\infty}$, or DOB (disturbance observer) technique, does not change much with the add-on controller except at the frequency of the disturbance. Since the add-on controller does the job of rejecting major eccentricity disturbance, the gain of the pre-designed controller does not have to be too high.