• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.1256-1263
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• 2022

With the advent of the Fourth Industrial Revolution, the amount of energy used in buildings has been increasing due to changes in the energy use structure caused by the massive spread of information-oriented equipment, climate change and greenhouse gas emissions. For the efficient use of energy, it is necessary to have a plan that can predict and reduce the amount of energy use according to the type of energy source and the use of buildings. To address such issues, this study presents a model embedded in a digital twin that predicts energy use in buildings. The digital twin is a system that can support a solution of urban problems through the process of simulations and analyses based on the data collected via sensors in real-time. To develop the energy use prediction model, energy-related data such as actual room use, power use and gas use were collected. Factors that significantly affect energy use were identified through a correlation analysis and multiple regression analysis based on the collected data. The proof-of-concept prototype was developed with an exhibition facility for performance evaluation and validation. The test results confirm that the error rate of the energy consumption prediction model decreases, and the prediction performance improves as the data is accumulated by comparing the error rates of the model. The energy use prediction model thus predicts future energy use and supports formulating a systematic energy management plan in consideration of characteristics of building spaces such as the purpose and the occupancy time of each room. It is suggested to collect and analyze data from other facilities in the future to develop a general-purpose energy use prediction model.

• Journal of Power Electronics
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• 제4권1호
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• pp.1-11
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• 2004

A stable adaptive sensorless speed controller for three-level inverter fed induction motor direct torque control (DTC) system using the radial-basis function network (RBFN) is presented in this paper. Torque ripple in the DTC system for high power induction motor could be drastically reduced with the foregoing researches of switching voltage selection and torque ripple reduction algorithms. However, speed control performance is still influenced by the inherent uncertainty of the system such as parametric uncertainty, external load disturbances and unmodeled dynamics, and its exact mathematical model is much difficult to be obtained due to their strong nonlinearity. In this paper, the inherent uncertainty is approximated on-line by the RBFN, and an additional robust control term is introduced to compensate for the reconstruction error of the RBFN instead of the rich number of rules and additional updated parameters. Control law for stabilizing the system and adaptive laws for updating both of weights in the RBFN and a bounding constant are established so that the whole closed-loop system is stable in the sense of Lyapunov, and the stability proof of the whole control system is presented. Computer simulations as well as experimental results are presented to show the validity and effectiveness of the proposed system.

• International Journal of Control, Automation, and Systems
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• 제3권3호
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• pp.387-396
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• 2005

The Rotational/Translational Actuator (RTAC) benchmark problem considers a fourth-order dynamical system involving the nonlinear interaction of a translational oscillator and an eccentric rotational proof mass. This problem has been posed to investigate the utility of a rotational actuator for stabilizing translational motion. In order to experimentally implement any of the model-based controllers proposed in the literature, the values of model parameters are required which are generally difficult to determine rigorously. In this paper, an approach to the least-squares estimation of the parameters of a system is formulated and practically applied to the RTAC system. On the other hand, this paper shows how to model a nonlinear system as a linear uncertain system via nonparametric system identification, in order to provide the information required for linear robust $H_\infty$ control design. This method is also applied to the RTAC system, which demonstrates severe nonlinearities, due to the coupling from the rotational motion to the translational motion. Experimental results confirm that this approach can effectively condense the whole nonlinearities, uncertainties, and disturbances within the system into a favorable perturbation block.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제5권2호
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• pp.123-132
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• 1998

Let F and G denote the distribution functions of the failure times and the censoring variables in a random censorship model. Susarla and Van Ryzin(1978) verified consistency of $F_{\alpha}$, he NPBE of F with respect to the Dirichlet process prior D($\alpha$), in which they assumed F and G are continuous. Assuming that A, the cumulative hazard function, is distributed according to a beta process with parameters c, $\alpha$, Hjort(1990) obtained the Bayes estimator $A_{c,\alpha}$ of A under a squared error loss function. By the theory of product-integral developed by Gill and Johansen(1990), the Bayes estimator $F_{c,\alpha}$ is recovered from $A_{c,\alpha}$. Continuity assumption on F and G is removed in our proof of the consistency of $A_{c,\alpha}$ and $F_{c,\alpha}$. Our result extends Susarla and Van Ryzin(1978) since a particular transform of a beta process is a Dirichlet process and the class of beta processes forms a much larger class than the class of Dirichlet processes.

• 천문학회지
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• 제36권2호
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• pp.73-73
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• 2003

Proof correction to the equation in the third paragraph of the DISCUSSION AND CONCLUSION has not been carried faithfully to the published version of the paper. The corrected equation should read ${\approx}10^{-3}\;M_8^4/^3(N_{\ast}/10^6\;pc^{-3})({\sigma}/300 km\;s^{-l})^{-l}(r/r_t)\;yr^{-1}$, where Ms is the mass of the SMBH in units of $10^8\;M_{\bigodot}$, $\sigma$ is the virial velocity of the stars, $r_t$ is the tidal radius of the SMBH. This estimates the frequency that a star would pass within a sphere with the radius r from the SMBH, rather than the frequency of the tidal disruption event. Therefore, it increases with the mass of the SMBH. However, the loss cone effect should also be taken into account, which reduces the actual event rate. Here, we adopted a factor of one hundred to consider the deficiency from the isotrophic rate. The authors sincerely regret this error.

• 한국소음진동공학회논문집
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• 제14권10호
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• pp.945-954
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• 2004

Recently, specifications of flat display module is going to be higher definition, brightness and more wide viewing angle. On the other hand, physical thickness of those modules is forced to be slimmer and lighter. The flat display modules such as plasma or TFT-LCD employ thin crystallized panels that are normally weak to high level transient mechanical energy inputs. As a result, anti-shock performance is one of the most important design specifications of TFT-LCD modules. TFT-LCD module manufacturers and their customers like PC or TV makers perform a series of strict impact/drop test for the modules. However most of the large display module designs are generated based on engineer's own trial-error experiences. Those designs may result in disqualification from the drop/impact test during final product evaluation. A rigorous study on the impact failure of the displays is of course necessitated in order to avoid the problems. In this article, a systematic design evaluation is presented with combinations of FEM modeling and testing to support the optimal shock proof display design procedure.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.395-400
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• 2017

연소 중 고압의 환경에 노출되는 밸브의 구조적 강도를 평가하기 위해 수압시험을 수행하였다. 수압 시험에서의 보증압력은 MEOP의 1.05배를 적용하였다. 총 2조의 밸브로 수압시험을 수행하였으며, 시험 시 가압조건에 따른 밸브의 변형률 계측결과를 유한요소해석 결과와 비교 검증하였다. 유한요소해석과 수압시험 결과의 오차는 약 20%이내이며, 소성변형은 발생하지 않았다.

• 조명전기설비학회논문지
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• 제15권3호
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• pp.74-82
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• 2001

유지·보수를 위한 비용과 선로의 안정성과 신뢰성을 저해하는 정전 등의 사고를 감소시키기 위해서는 오손정도에 대한 정확한 측정이 선행되어야만 한다. 그러나, IEC 60815 등을 통해 추천되어 많은 연구에 있어 사용되어 온 수동 필세법은 인력, 비용, 측정오차 등의 측면에 있어 많은 문제점을 지니고 있다. 이에 본 연구에서는 옥외 환경에서 사용되는 애자표면의 오손정도를 측정할 수 있는 새로운 형태의 자동측정장치의 개발을 목적으로 한 일련의 연구를 수행하고자 한다. 장비의 설계 및 평가를 위해 FLUX 2D를 이용한 시뮬레이션과 인공오손과 관련한 다양한 실험을 수행하였다. 이와 같은 노력의 결과, 새로운 형태의 오손도 자동측정장치의 개발에 있어 중요한 것으로 사려되는 몇몇 결론을 얻을 수 있었다.

• 한국정밀공학회지
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• 제21권3호
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• pp.38-43
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• 2004

This paper describes the construction of a circular polariscope. Generally, a circular polariscope contains four optical elements and a light source. The first element following the light source is called the linear polarizer. It converts the ordinary light into plane-polarized light. The second element is a quarter wave plate which converts the plane-polarized light into circularly polarized light. Following the quarter wave plate, a specimen made of transparent photoelastic material is located in a loading device. The second quarter wave plate is set and the last element is the analyzer. These polarizing elements, two quarter wave plates and two linear polarizing filters, were purchased from the USA. Frames and other structures for holding polarizing filters were machined and assembled to be rotated. Light box, which includes four incandescent lamps and two sodium-vapor lamps, was made. In order to proof the function of the newly built polariscope, Tardy compensation test was applied to a rectangular shaped specimen made of poly-carbonate material (PSM 1). The error of the fringe constant, which was measured by the newly built polariscope, was within 4.4 percent compared to the standard value of this material. It is possible to make a good quality of polariscope if accurate polarizing filters will be used.

• 한국광학회지
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• 제12권2호
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• pp.71-76
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• 2001

자연의 법칙이 보장해 주는 완벽한 보안이 가능한 양자암호화 통신을 위해서는 아주 약한 빛을 사용해 한 펄스에서 두 개 이상의 광자가 발견될 확률을 아주 작게 해야한다. 그러나 잡음과 검출기의 양자효율 등을 고려하면 현실적으로는 실험적 상황에서 발생되는 신호왜곡과 도청에 의한 신호왜곡을 구별해 낼수 있는 조건을 찾아내야 한다. 검출기에 걸어주는 전압의 크기와 신호검출시의 문턱전압을 변화시켜가며 여러 세기의 빛에 대한 양자암호화 키 전송가능성을 실험적으로 확인하였다. 암호화 키전송 방식은 잘 알려진 두 가지 선형편광과 두가지 원형편광 상태를 이용한 4-state 암호화 키 전송방식을 사용하였다.