• Nuclear Engineering and Technology
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• 제47권4호
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• pp.407-415
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• 2015

A developing post-dryout region is characterized by significant heat transfer enhancements compared with the fully developed post-dryout region. The heat transfer enhancements are mainly due to upstream disturbance and entrained droplets in the region immediately downstream of the critical heat flux location. In this paper, an improved heat transfer correlation is developed for the developing post-dryout regions in vertical tubes over a wide range of flow conditions. The correlation represents a correction factor for the fully developed film-boiling look-up table to be applied to the developing post-dryout region. The new correlation significantly improves the heat transfer prediction in the developing post-dryout regions and provides very good agreement with the experimental data.

• 전자공학회논문지B
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• 제29B권9호
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• pp.76-87
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• 1992

A novel self-organizing fuzzy plus PD control algorithm is proposed, where the proposed controller consists of a typical fuzzy reasoning part and self organizing part in which both on-line and off-line algorithms are employed to modify the Look-Up Table(LUT) for the fuzzy control rules and to decide how much fuzzy rules are to be modifid after evaluating the control performance, respectively. And the fuzzy controller is replaced by a PD controller in a prespecified region nearby the set point for good settling actions, where gain parameters are determined by fuzzy rules based on the magnitude of error velocity at the instant when the output penetrates into the prespecified region. To show the effectiveness of the proposed controller, extensive computer simulation results as well as experimental results are illustrated for an inverted pendulum system.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 1999년도 가을 학술발표논문집 Vol.26 No.2 (3)
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• pp.3-5
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• 1999

나눗셈 알고리즘은 다른 덧셈이나 곱셈 알고리즘에 비해 복잡하고, 수행 빈도수가 적다는 이유로 그동안 고속 나눗셈의 하드웨어 연구는 활발하지 않았다. 그러나 멀티미디어의 발전 및 고성능의 그래픽 랜더링을 위한 보다 빠른 부동소수점연산기(FPU)가 필요하게 되었으며, 이에 따라서 고속의 나눗셈 연산기의 필요성이 증가하게 되었다. 특히, 전체의 수행 시간 향상을 위해서라도 고속 나눗셈 연산기의 중용성은 더욱 부각되고 있다. 그러나 고속 나눗셈 연산기는 연산 속도와 크기라는 서로 상반되는 요소를 가지고 있다. 즉, 연산 속도가 빠르면 크기는 늘어나고, 크기를 줄이면 연산 속도는 늦어지게 된다. 본 논문은 높은 자릿수(Very-High Radix) 나눗셈 알고리즘에서 영역변환상수를 구하는 방법으로 연산이 아닌 검색테이블(Look-up Table)을 이용한다. 그리고 검색테이블의 크기를 줄이는 방법으로 영역변환상수의 범위 분석 및 캐리 저장형을 이용한 검색테이블 분할 방법을 이용하였다. 전체적으로는 영역변환상수를 구하는 연산주기가 필요없게 되므로 나눗셈 연산기의 영역 크기의 변화가 적으면서 연산 속도는 빨라졌음을 알 수 있다.

• Smart Structures and Systems
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• 제20권1호
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• pp.61-74
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• 2017

One of the most reliable and simplest tools for structural vibration control in civil engineering is Tuned Mass Damper, TMD. Provided that the frequency and damping parameters of these dampers are tuned appropriately, they can reduce the vibrations of the structure through their generated inertia forces, as they vibrate continuously. To achieve the optimal parameters of TMD, many different methods have been provided so far. In old approaches, some formulas have been offered based on simplifying models and their applied loadings while novel procedures need to model structures completely in order to obtain TMD parameters. In this paper, with regard to the nonlinear decision-making of fuzzy systems and their enough ability to cope with different unreliability, a method is proposed. Furthermore, by taking advantage of both old and new methods a fuzzy system is designed to be operational and reduce uncertainties related to models and applied loads. To design fuzzy system, it is required to gain data on structures and optimum parameters of TMDs corresponding to these structures. This information is obtained through modeling MDOF systems with various numbers of stories subjected to far and near field earthquakes. The design of the fuzzy systems is performed by three methods: look-up table, the data space grid-partitioning, and clustering. After that, rule weights of Mamdani fuzzy system using the look-up table are optimized through genetic algorithm and rule weights of Sugeno fuzzy system designed based on grid-partitioning methods and clustering data are optimized through ANFIS (Adaptive Neuro-Fuzzy Inference System). By comparing these methods, it is observed that the fuzzy system technique based on data clustering has an efficient function to predict the optimal parameters of TMDs. In this method, average of errors in estimating frequency and damping ratio is close to zero. Also, standard deviation of frequency errors and damping ratio errors decrease by 78% and 4.1% respectively in comparison with the look-up table method. While, this reductions compared to the grid partitioning method are 2.2% and 1.8% respectively. In this research, TMD parameters are estimated for a 15-degree of freedom structure based on designed fuzzy system and are compared to parameters obtained from the genetic algorithm and empirical relations. The progress up to 1.9% and 2% under far-field earthquakes and 0.4% and 2.2% under near-field earthquakes is obtained in decreasing respectively roof maximum displacement and its RMS ratio through fuzzy system method compared to those obtained by empirical relations.

• 전자공학회논문지CI
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• 제38권5호
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• pp.44-57
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• 2001

문법적으로 정확한 한국어 음성을 합성하려면 표준어 규정의 '표준 발음법'을 준용해야 한다. 따라서 한국어 음가 합성 시스템에 사용되는 한글을 음성으로 변환하여 주는 규칙은 '표준 발음법'을 완전하게 반영하며 또한 무결해야 한다. 기존의 연구에서는 표준 발음법을 검증없이 적용하여 왔고, 표준 발음법 자체에 모순이 있는가의 여부에 대해서도 체계적인 분석을 위한 시도가 진부하였다. 본 논문에서는 한국어 음가 생성의 기본 규칙으로 준용할 표준 발음법을 페트리 넷으로 모델링하여 표준 발음법의 일관성을 검증하였다. 그리고, 음운 변동 현상을 여러 단계로 나누어 차례로 적용한다든지, 변동된 단어에 대하여 처음부터 다시 변환 작업을 재수행하는 기존의 음가 생성 방법의 문제점을 해결하기 위하여 한번의 테이블 탐색으로 모든 음운 변동이 완료되는 한국어 음성 합성을 위한 음가 변환 테이블을 구현하였다.

• 대한원격탐사학회지
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• 제3권1호
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• pp.41-54
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• 1987

극궤도 기상위성 NOAA-9호의 AVHRR Channel 4 영상 data로부터 해수면온도(SST)를 산출하는 과정을 기상연구소의 위성수신 시스템에 맞도록 개발하였다. 위성의 Ascending node를 기준으로 영상좌표와 SST용 Mercator 지도 좌표변환용 Table 을 만 들고 10 km $\times$ 10 km의 Sample로 SST용 영상을 제작하였다. 또, 위성측기의 복사보 정 (Radiometric Calibration) 과정과 적외선 CH 4 인 10.5 ~ 11.5 $\mu\textrm{m}$의 복사를 온도로 변환 (Radiance-To-Temperature Conversion)하는 LUT(Look Up Table)의 작성 및 SST 출력과정을 제작하였다.

• 조명전기설비학회논문지
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• 제28권11호
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• pp.112-122
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• 2014

This paper proposes a PMSM torque control method considering DC-link voltage variation and friction torque. In general EV/HEV application, two dimensions look-up table(2D-LUT) is used for reference current generation due to its stable and robust torque control performance. Conventionally, this 2D-LUT is established by flux-torque table to overcome the DC-link voltage variation. However, the flux table establishment is more complex than the speed table establishment. Moreover, one flux data reflects several speed conditions in variable DC-link voltage, friction torque cannot be considered by using the flux table. In this paper, speed-torque 2D-LUT is used for current reference generation. With this table, PMSM torque control is well achieved regardless of DC-link voltage variation by the proposed control method. Simulation and experimental results validate improvement of torque control error through friction torque compensation.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2006년도 추계학술대회 발표 논문집
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• pp.184-189
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• 2006

In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by rising experiment and simulation. Optimal design for a passive air spring can be obtained by fluting the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the act ive vibration isolation table wi th the bet ter isolation performance.

• 전자공학회논문지S
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• 제34S권1호
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• pp.26-35
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• 1997

In this paper, a VHDL implementation method for the internet protocol (IP) placed on top of ATM, so called IP over ATM, is presented. The proposed implementation method employs a parallel processing architecture to reduce the processing time and offers 155.52Mbps (STM-1) interface with the full-duplex mode for the ATM-based network. Furthermore, in order to minimize the search time for the table look-up, a LANCAM-based structure combining the routing table with the ATMARP table is proposed. The VHDL simulation results show that this proposed method can transmit (receive) at 155.52Mbps with delays of 48.5 clocks (29.5clocks).

• Journal of Power Electronics
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• 제15권1호
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• pp.160-176
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• 2015

This paper presents a method of designing optimal integer- and fractional-order proportional-integral-derivative (FOPID) controllers for a boost converter to gain a set of favorable characteristics at various operating points. A Pareto-based multi-objective optimization approach called strength Pareto evolutionary algorithm (SPEA) is used to obtain fast and low overshoot start-up and dynamic responses and switching stability. The optimization approach generates a set of optimal gains called Pareto set, which corresponds to a Pareto front. The Pareto front is a set of optimal results for objective functions. These results provide designers with a trade-off look-up table, in which they can easily choose any of the optimal gains based on design requirements. The SPEA also overcomes the difficulties of tuning the FOPID controller, which is an extension to the classic integer-order PID controllers and potentially promises better results. The proposed optimized FOPID controller provides an excellent start-up response and the desired dynamic response. This paper presents a detailed comparison of the optimum integer- and the fractional-order PID controllers. Extensive simulation and experimental results prove the superiority of the proposed design methodology to achieve a wide set of desired technical goals.