• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권3호
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• pp.167-173
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• 2002

In this paper, we propose an interactive genetic algorithm (IGA) to implement an automated 2D avatar synthesis. The IGA technique is capable of expressing user's personality in the avatar synthesis by using the user's response as a candidate for the fitness value. Our suggested IGA method is applied to creating avatars automatically. Unlike the previous works, we introduce the concepts of 'hidden population', as well as 'primitive avatar' and 'simplified genotype', which are used to overcome the shortcomings of IGA such as human fatigue or reliability, and reasonable rates of convergence with a less number of iterations. The procedure of designing avatar models consists of two steps. The first step is to detect the facial feature points and the second step is to create the subjectively optimal avatars with diversity by embedding user's preference, intuition, emotion, psychological aspects, or a more general term, KANSEI. Finally, the combined processes result in human-friendly avatars in terms of both genetic optimality and interactive GUI with reliability.

• 한국항공우주학회지
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• 제34권6호
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• pp.35-41
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• 2006

본 논문에서는 무밸브 마이크로펌프에 사용되는 압전 다이아프램의 성능을 향상시키는 방법이 연구되었다. 큰 작동 변위와 작동력을 가지는 원형 형태의 경량 압전 복합재료 작동기(LIPCA)를 마이크로 펌프용으로 제작하였다. 유한요소 해석과 실험을 통하여 원형 LIPCA의 성능을 예측하여 최적의 적층 형태를 설계하였다. 최적의 원형 LIPCA를 기반으로 포토리소그라피법과 PDMS 몰딩법을 사용하여 무밸브 마이크로 펌프를 제작하였다. 압전 다이아프램의 작동 변위 및 마이크로 펌프의 유량과 배압을 실험적으로 계측하였고, 반경험식을 사용하여 예측한 유량과 비교하였다. 이상의 연구에서 원형 LIPCA가 마이크로 펌프용으로 사용되는 보통의 압전 작동 다이아프램을 대체할 수 있는 우수한 작동기임을 확인할 수 있었다.

• 한국산학기술학회논문지
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• 제5권1호
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• pp.69-72
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• 2004

상품 정보를 저장하기 위해 현재 널리 사용되고 있는 바코드에 비해, 칼라코드는 미관상 수려하고 더 많은 조합을 수용할 수 있기 때문에, 용도가 더 다양하다. 그러나, 실제 사용에 있어서 수집된 이미지에서의 칼라코드는 환경 또는 장비에 의해 색깔이 심하게 왜곡될 수 있다. 이 논문에서는 이러한 왜곡에 의한 영향을 줄이고, 미로 찾기에 사용되는 우선법(Right hand on wall) 알고리즘을 이용하여 효율적으로 칼라코드를 검출하는 방법을 제시한다. 이 논문에서 사용하는 칼라코드는 Hue 값과 Saturation값이 높은 색들을 사용하는 동심원형이며, 프리프로세싱에 의해 전체 이미지에서 칼라코드의 후보 영역을 검출한 견과 이미지에 우선법 알고리즘을 적용하여 각 후보 영역을 포함하는 최적 직각사각형의 좌표를 도출한다. 실험결과, 우선법을 적용하여 칼라코드 영역의 정확한 좌표를 도출할 수 있었다.

• Journal of Communications and Networks
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• 제17권5호
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• pp.499-505
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• 2015

We analyze the performance of multistage cooperation in decode-and-forward relay networks where the transmission between source and destination takes place in $T{\geq}2$ equal duration and orthogonal time phases with the help of relays. The source transmits only in the first time phase. All relays that can decode the source's transmission forward the source's message to the destination in the second time phase, using a space-time code. During subsequent time phases, the relays that have successfully decoded the source message using information from all previous transmitting relays, transmit the space-time coded symbols for the source's message. The non-decoding relays keep accumulating information and transmit in the later stages when they are able to decode. This process continues for T cooperation phases. We develop and analyze the outage probability of multistage cooperation protocol under orthogonal relaying. Through analytical results, we obtain the near-optimal placement strategy for relays that gives the best performance when compared with most other candidate relay location strategies of interest. For different relay network topologies, we also investigate an interesting tradeoff between an increased SNR and decreased spectral efficiency as the number of cooperation stages is increased. It is also shown that the largest multistage cooperation gain is obtained in the low and moderate SNR regime.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.979-988
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• 2009

Tensioned metastable fluids provide a powerful means for low-cost, efficient detection of a wide range of nuclear particles with spectroscopic capabilities. Past work in this field has relied on one-component liquids. Pure liquids may provide very good detection capability in some aspects, such as low thresholds or large radiation interaction cross sections, but it is rare to find a liquid that is a perfect candidate on both counts. It was hypothesized that liquid mixtures could offer optimal benefits and present more options for advancement. However, not much is known about radiation-induced thermal-hydraulics involving destabilization of mixtures of tensioned metastable fluids. This paper presents results of experiments that assess key thermophysical properties of liquid mixtures governing fast neutron radiation-induced cavitation in liquid mixtures. Experiments were conducted by placing liquid mixtures of various proportions in tension metastable states using Purdue's centrifugally-tensioned metastable fluid detector (CTMFD) apparatus. Liquids chosen for this study covered a good representation of both thermal and fast neutron interaction cross sections, a range of cavitation onset thresholds and a range of thermophysical properties. Experiments were devised to measure the effective liquid mixture viscosity and surface tension. Neutron-induced tension metastability thresholds were found to vary non-linearly with mixture concentration; these thresholds varied linearly with surface tension and inversely with mixture vapor pressure (on a semi-log scale), and no visible trend with mixture viscosity nor with latent heat of vaporization.

• International Journal of Contents
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• 제5권1호
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• pp.51-55
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• 2009

In this paper, we present a structure of personalized e-Learning system to study for a test formalized by uniform multiple-choice using on/off line mixed estimations as is the case of Driver :s License Test in Korea. Using the system a candidate can study toward the license through the Internet (and/or mobile instruments) within the personalized concept based on IRT(item response theory). The system accurately estimates user's ability parameter and dynamically offers optimal evaluation problems and learning contents according to the estimated ability so that the user can take possession of the license in shorter time. In order to establish the personalized e-Learning concepts, we build up 3 databases and 2 agents in this system. Content DB maintains learning contents for studying toward the license as the shape of objects separated by concept-unit. Item-bank DB manages items with their parameters such as difficulties, discriminations, and guessing factors, which are firmly related to the learning contents in Content DB through the concept of object parameters. User profile DB maintains users' status information, item responses, and ability parameters. With these DB formations, Interface agent processes user ID, password, status information, and various queries generated by learners. In addition, it hooks up user's item response with Selection & Feedback agent. On the other hand, Selection & Feedback agent offers problems and content objects according to the corresponding user's ability parameter, and re-estimates the ability parameter to activate dynamic personalized learning situation and so forth.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제9권6호
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• pp.131-136
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• 2020

차량 환경의 통신에서 콘텐츠의 사전 캐싱은 사용자로부터 콘텐츠 서버까지의 지연시간을 감소시킬 수 있다. 하지만 어디에, 어느 량 만큼의 사전 캐싱을 해야하는 지에 대한 문제점은 아직도 해결되지 않고 있다. 본 논문에서는 차량의 이동 확률을 토대로 차량이 다음으로 이동하게 될 기지국 후보들에게 각각 최적화된 량만큼의 콘텐츠를 분산시켜 사전 캐싱하는 방안을 제시한다. 우선, 각 차량의 이동 확률은 Markov Chain을 이용하여 학습되었다. 그리고 분산하여 사전 캐싱할 콘텐츠의 량은 무선 환경을 기반으로 최적화되었다. NS-3를 기반으로 진행된 실험에서 제안방안은 기존 방안에 비하여 최소의 지연시간을 유지하며 트래픽을 가장 많이 절약한 결과가 도출되었다.

• Journal of information and communication convergence engineering
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• 제11권4호
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• pp.288-292
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• 2013

In this paper, a carbon implant is investigated in detail from the perspectives of performance advantages and side effects for the thick n-type metal-oxide-semiconductor field-effect transistor (n-MOSFET). Threshold voltage ($V_{th}$) adjustment using a carbon implant significantly improves the $V_{th}$ mismatch performance in a thick (3.3-V) n-MOS transistor. It has been reported that a bad mismatch occurs particularly in the case of 0.11-${\mu}m$ $V_{th}$ node technology. This paper investigates a carbon implant process as a promising candidate for the optimal $V_{th}$ roll-off curve. The carbon implant makes the $V_{th}$ roll-off curve perfectly flat, which is explained in detail. Further, the mechanism of hot carrier injection lifetime degradation by the carbon implant is investigated, and new process integration involving the addition of a nitrogen implant in the lightly doped drain process is offered as its solution. This paper presents the critical side effects, such as Isub increases and device performance shifts caused by the carbon implant and suggests an efficient method to avoid these issues.

• 디지털콘텐츠학회 논문지
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• 제18권5호
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• pp.969-976
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• 2017

본 논문에서는 최적화 알고리즘으로 개발된 WFSO(Water Flowing and Shaking Optimization) 알고리즘을 사용한 인공신경망 과합성공 신경망의 학습 방법을 제안한다. 최적화 알고리즘은 다수의 후보 해를 기반으로 탐색해 나가기 때문에 일반적으로 속도가 느린 단점이 있으나 지역 최소값에 거의 빠지지 않고 병렬화가 용이하며 미분 불가능한 활성화함수를 갖는 인공신경망 학습도 가능하고 구조와 가중치를 동시에 최적화 할 수 있는 장점이 있다. 본 논문에서는 WFSO 알고리즘을 인공신경망 학습에 적용하는 방법을 설명하고 다층 인공신경망과 합성곱 신경망에서 오류역전파 알고리즘과 성능을 비교한다.

• 대한기계학회논문집B
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• 제32권9호
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• pp.669-675
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• 2008

The objectives of this paper are to examine the effect of nano-particles on the pool type absorption heat transfer enhancement and to find the optimal conditions to design a highly effective compact absorber for ammonia/water absorption system. The effect of $Al_2O_3$ nano-particles and carbon nanotube(CNT) on the absorption performance is studied experimentally. The experimental ranges of the key parameters are 20% of ammonia concentration, $0{\sim}0.08\;vol%$ (volume fraction) of CNT particles, and $0{\sim}0.06 \;vol%$ of $Al_2O_3$ nano-particles. For the ammonia/water nanofluids, the heat transfer rate and absorption rate with 0.02 vol% $Al_2O_3$ nano-particles were found to be 29% and 18% higher than those without nano-particles, respectively. It is recommended that the concentration of 0.02 vol% of $Al_2O_3$ nano-particles be the best candidate for ammonia/water absorption performance enhancement.