• Advances in aircraft and spacecraft science
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• v.4 no.5
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• pp.543-553
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• 2017

Vibration is a source of performance degradation in all optical imaging systems. Performance of high resolution remote sensing payloads is often limited due to satellite platform vibrations. Effects of Linear and high frequency sinusoidal vibrations on the system MTF are known exactly in closed form but the low frequency vibration effects is a random process and must be considered statistically. Usually the vibration MTF budget is defined based on the mission requirements and the overall MTF limitations. For analyzing low frequency effects, designer must know all the systems specifications and parameters. With a good understanding of harmful vibration frequencies and amplitudes in the system preliminary design phase, their effects could be removed totally or partially. This procedure is cost effective and let the designer to eliminate just harmful vibrations and avoids over-designing. In this paper we have analyzed the effects of low-frequency platform vibrations on the payload's modulation transfer function. We have used a statistical analysis to find the probability of imaging with a MTF equal or greater than a pre-defined budget for different missions. The worst and average cases have been discussed and finally we have proposed "look-up figures". Using these look-up figures, designer can choose the electro-optical parameters in such a way that vibration effects be less than its pre-defined budget. Furthermore, using the results, we can propose a damping profile based on which vibration frequencies and amplitudes must be eliminated to stabilize the payload system.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.255-258
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• 1999

본 논문에서는 파동 방정식으로부터 클래식 기타의 Physical 모델을 유도해 낸 후 이를 구현하였다. 이러한 모델을 이용해 별도의 음원 데이터를 사용하지 않고 현재 전자 음악에서 일반적으로 사용되는 table look-Up 방식보다 효율적으로 악기 음을 함성 할 수 있도록 하였다. 파동 방정식은 현의 장력, 길이 및 질량 데이터를 이용해 현의 움직임을 표현한 것이며 이 식으로부터 Fourier Series를 유도하고 다시 Z 변환을 거쳐 현의 운동을 모델링하였다. 이 과정에서 현의 양끝에서 반사되는 신호의 크기를 모델링에 포함 시켰다. 이러한 현의 모델은 모든 종류의 현악기에 공통으로 적용될 수 있으며 현의 장력 길이, 질량 데이터를 변화해 다양한 현의 특성들을 모델링 할 수 있다. 또 음 합성을 위해 현의 초기 상태 및 연속되는 입력 데이터를 바꿔 클래식 기타의 다양한 음들을 합성 할 수 있다. 클래식 기타의 Physical 모델을 평가하기 위해, 실제 악기 음 및 table look-up 방식으로 합성된 음들을 녹음해 서로 비교하였다. 시간 및 주파수 도메인 상에서 비교가 이뤄 졌으며 table look-up 합성 방식에서 모든 주파수대가 동일하게 감소하고 비슷한 음역에서 음 높이에 적합한 배음 주파수 비율을 조절할 수 없는 등, 각 을의 특성들을 정확히 묘사할 수 없는 문제점을 극복할 수 있었다.

• Journal of IKEEE
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• v.3 no.2 s.5
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• pp.276-284
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• 1999

In this paper, we propose a new technique which allows to store the pre-scaling constants directly in a table thus eliminating the cycle for computing pre-scaling constants. Especially we analyzed the range of pre-scalingconstants and rearranged them in a carry-save form using two look-up tables so that the size of the tables can be reduced significantly. The resulting scheme is compared with the previously developed method and shown to be effective with respect to area and time to implement the high-radix divider.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.388-398
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• 1998

In constructing fuzzy control systems. there are many parameters such as rule base. membership functions. inference m method. defuzzification. and I/O scaling factors. To control the system in properly using fuzzy logic. we have to consider t the correlation with those parameters. This paper deals with self-tuning of fuzzy control systems. The fuzzy controller h has parameters that are input and output scaling factors to effect control output. And we propose the looklongleftarrowup table b based self-tuning fuzy controller. We propose the PMTM(Plus-Minus Tuning Method) for self tuning method, self-tuning the initial look-up table to the appropriate table by adding and subtracting the values.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.11a
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• pp.60-62
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• 2016

이동통신 시스템의 OFDM(Othogonal frequency division multiplexing) 신호는 큰 PAPR(Peak to Average Power Ratio)을 가지기 때문에 비선형 특성을 가지는 전력 증폭기의 효율 감소를 가져온다. 이러한 전력 증폭기의 비선형 특성을 개선하여 효율을 증가시키기 위해서 전력 증폭기의 역 특성을 가지는 디지털 전치 왜곡기가 이용된다. 본 논문에서는 제곱근 근사를 이용한 Look-up Table(LUT) 기반의 디지털 전치왜곡(Digital Pre-Distortion :DPD) 기법을 제안한다. 제안하는 방식은 복소 이득(Complex Gain) LUT 구조에서 입력신호의 크기를 구할 때, 기존의 테이블을 이용하여 제곱근 연산을 하는 방식보다 좋은 성능을 내면서 근사를 위한 테이블의 메모리를 필요로 하지 않는다. 또한 간단한 쉬프트 연산 등을 이용하므로 DSP 또는 MCU 기반의 DPD를 구현할 때 간단하게 구현 될 수 있다는 장점을 갖는다. 컴퓨터 모의실험을 통해 제안하는 제곱근 근사방식을 이용한 DPD와 기존의 방식을 사용한 DPD를 비교함으로써 제안하는 방식이 기존 방식보다 좋은 성능을 내면서도 보다 효율적으로 구현될 수 있음을 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.78-89
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• 2012

The generated torque of a switched reluctance(SR) motor is highly nonlinear, which makes it difficult to determine the reference current commands for minimum torque ripples. In this paper, we present a computationally simple and efficient method to minimize torque ripples of SR motors based on iterative learning control. The reference current command of each phase minimizing torque ripples is identified in 2-dimensional look-up table form. Our learning control algorithm does not require the torque model, so our method is not affected by model errors and hence is very accurate. In order to justify our work, we present some computer simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.379-385
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• 2004

Medical images are being managed more by PACS in general medical institutions. It is important to protect patients from being invaded their privacy related to the images. It is also necessary to confirm the ownership, the right of property of the medical images and notice whether the data are modified. In this paper, we propose a robust watermarking against RST attacks in medical images on the PACS. The proposed scheme modifies and improves Log-Polar Mapping and Fourier Mellin Transform in order to realize and recover serious image degradation and watermark data loss caused by the conversion between cartesian coordinate and log-polar coordinate. We used the radius and theta Look Up Table to solve the realization of the Fourier Mellin Transform, and inserted a watermark into 2D-DFT magnitudes using Spread Spectrum. Experimental results shows that this method are robust to rotation attack.

• Journal of Fashion Business
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• v.11 no.4
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• pp.52-68
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• 2007

[ $Courr{\grave{e}}ges$ ]Look style has been showing up continuously since 1980s in the fashion world. In response to that, this study aimed to look into the trend of design in 1960s and examine the formative artistic characteristics in $Courr{\grave{e}}ges$ Look in order to explore the $Courr{\grave{e}}ges$ Look of Andre Courregs. Following the flow of the times, the $Courr{\grave{e}}ges$'s design has transformed and developed through the styles of the pants suit look, the space age look, the mini look and the sporty look. His own style constructed by simple line like a mini skirts, accurate rates, geometric patterns, high tech materials, vivid color and etc, in 1960s. He has also innovated the fields of textile, garment cutting, details, and accessories. The $Courr{\grave{e}}ges$ Style was expressed by pure&avant-garde style, sporty&modern style, cheerful&reveal style and dynamic&funny style. Functionality with humor to $Courr{\grave{e}}ges$ was an important element that expresses both youth and casual. For the active, new woman, not only a funtional beauty but also a futuristic sensibility is expressed in the $Courr{\grave{e}}ges$ Style.

• Journal of the Korean Society of Costume
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• v.50
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• pp.97-118
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• 2000

The purposes of the present research were (1) to investigate the sociological factors influencing the increase of ambivalence and the relationship between, the ambivalence and fashion change(2) to categorize sets of the ambivalence expressed for contemporary fashion and (3) to examine the frequency and the patterns of ambivalence presented for contemporary fashion. This research was conducted through in depth literature review and content analysis. Data was collected from 806 colored pictures presented on 'Collections' from 1972 to 1988. Eight types of clothing cues were incluede: look color texture decorative motifs of clothing collar sleeve and wearer's headdress/hair style and make-up. The results of this study were as follows: 1 The popularization of culture has been accelerated by mass production mass consumption and mass media. Since the 1980s postmodernism and poststructuralism have resulted in the breakdown of dualistic distinction. As the ambiguity of meaning in appearance increases the meaning is negotiated constantly for identity. 2. The most frequenctly expressed ambivalence in clothing was feminity/masculinity and tradition/modernity and wealth/poverty was the least. The number of ambivalent expression were the highest during 1990s. The rapid growth in ambivalence of tradition/modernity was found in 1970s feminity/masculinity in 1980s and modesty/immodesty in 1990s. Within a clothing style ambivalence was manifested through feminine look in white for beauty/ugliness feminine look mainly in yellow/red for wealty/poverty sexy look dominantly in black for modesty/immodesty androgynous look in black for feminity/masculinity and through ecology look most frequently in black for tradition/modernity.

• Health Policy and Management
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• v.26 no.1
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• pp.71-78
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• 2016

The value of using health insurance claim database is continuously rising in healthcare research. In studies where comorbidities act as a confounder, comorbidity adjustment holds importance. Yet researchers are faced with a myriad of options without sufficient information on how to appropriately adjust comorbidity. The purpose of this study is to assist in selecting an appropriate index, look back period, and data range for comorbidity adjustment. No consensus has been formed regarding the appropriate index, look back period and data range in comorbidity adjustment. This study recommends the Charlson comorbidity index be selected when predicting the outcome such as mortality, and the Elixhauser's comorbidity measures be selected when analyzing the relations between various comorbidities and outcomes. A longer look back period and inclusion of all diagnoses of both inpatient and outpatient data led to increased prevalence of comorbidities, but contributed little to model performance. Limited data range, such as the inclusion of primary diagnoses only, may complement limitations of the health insurance claim database, but could miss important comorbidities. This study suggests that all diagnoses of both inpatients and outpatients data, excluding rule-out diagnosis, be observed for at least 1 year look back period prior to the index date. The comorbidity index, look back period, and data range must be considered for comorbidity adjustment. To provide better guidance to researchers, follow-up studies should be conducted using the three factors based on specific diseases and surgeries.