• 한국지능시스템학회논문지
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• 제10권4호
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• pp.330-337
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• 2000

본 논문은 10개 교차로를 연동제어를 할 수 있는 새로운 교통체제 개념을 제안한다. 예를 들어서 오늘 야구경기가 8시경에 열린다고 하면 야구경기가 시작하기 전 1 시간 혹은 1시간 혹은 1시간 30분전에 교통량이 증가할 것이다. 이럴 때에는 아무리 우수한 전자 신호등 시스템도 최적녹색시간을 예측할 수 없다. 그러므로, 본 논문에서는 평균 승용차 대기시간을 최소화하고 평균 주행속도를 향상하기 위해서 퍼지규칙 및 신경망을 이용한다. 모의실험결과 제안된 연동 녹색시간이 연동 녹색 시간을 고려하지 않은 전자신호등보다 평균 승용차 대기시간을 줄일 수 있음을 입증했다.

• Journal of Biosystems Engineering
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• 제26권4호
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• pp.355-362
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• 2001

Uniform application of agri-chemicals will improve orchard pest management. An air-blast(orchard) sprayer designed for vineyards has been used: however, few research on the uniformity and coverage of the sprays has been reported. Distributions of spray coverage were measured with artificial targets and analyzed to enhance the efficiency of spray application. A structure was built to place water sensitive papers, sampling spray droplets blasted from the orchard sprayer. The sampling cards were collected from five directions at three distances (2.5, 3.0 and 3.5m) for two fan speeds (2,075 and 3,031 rpm), and analyzed using an image analysis system. The distribution of the coverage percent area did not follow the wind velocity pattern. The coverage by the low fan speed was more uniform and higher than that by the higher fan speed. The coverage percent area decreased with an increase of distance. The distribution of droplet density was similar to that of coverage. However, the coverage contribution by smaller droplets became more significant as the distance increased. The upward blasting distance was limited within 3m, but the limit to the ground level was expanded the distance more than 3.5m because of the concentrated droplets.

• Journal of Biosystems Engineering
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• 제22권2호
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• pp.137-150
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• 1997

To investigate the feasibility of a boom sprayer in the paddy field, an experimental boom sprayer for both broadcast and directed spraying to the lower part of rice plants was developed. The droplet deposition characteristics of the boom sprayers were experimentally compared to those of power sprayer. Water sensitive papers(WSP) and a machine vision system were used to evaluate the coverage rate and droplet density. It was shown that the broadcast application by the boom sprayer was the best coverage among the tested sprayers. Coverage tate and droplet density were affected by the distance between nozzles and the sprayer ground speed, The best result was obtained when the distance of 30cm and the speed of 1.7km/hr. The directed application showed inconsistency in overall droplet distribution. The inconsistency was judged to be caused by conflict between plants and boom extenders. The power sprayer showed a very wide range of droplet size distribution, relatively larger droplets and inconsistency in cove The power sprayer was judged to be inadequate for the low-volume precision application because of inconsistency in performance and difficulty in adjusting the spraying rate. Based on the droplet coverage characteristics, it was concluded that the self-propelled boom sprayer for the broadcast application was feasible for an alternative to the power sprayer in case of low volume, precision application in paddy condition.

• 대한기계학회논문집B
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• 제32권6호
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• pp.454-462
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• 2008

Since operating conditions are significantly different for heating and cooling mode operations in a $CO_2$ heat pump system, it is difficult to optimize the performance of the $CO_2$ cycle. In addition, the performance of a $CO_2$ heat pump is very sensitive to outdoor temperature and gascooler pressure. In this study, the cooling and heating performances of a variable speed $CO_2$ heat pump with a twin-rotary compressor were measured and analyzed with the variations of EEV opening and compressor frequency. As a result, the cooling and heating COPs were 2.3 and 3.0, respectively, when the EEV opening was 22%. When the optimal EEV openings for heating and cooling were 28% and 16%, the cooling and heating COPs increased by 3.3% and 3.9%, respectively, over the COPs at the EEV opening of 22%. Beside, the heating performance was more sensitive to EEV opening than the cooling performance. As the compressor speed decreased by 5 Hz, the cooling COP increased by 2%, while the heating COP decreased by 8%.

• 전자통신동향분석
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• 제36권6호
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• pp.1-12
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• 2021

As the demand for big data and big data-based artificial intelligence (AI) technology increases, the need for privacy preservations for sensitive information contained in big data and for high-speed encryption-based AI computation systems also increases. Fully homomorphic encryption (FHE) is a representative encryption technology that preserves the privacy of sensitive data. Therefore, FHE technology is being actively investigated primarily because, with FHE, decryption of the encrypted data is not required in the entire data flow. Data can be stored, transmitted, combined, and processed in an encrypted state. Moreover, FHE is based on an NP-hard problem (Lattice problem) that cannot be broken, even by a quantum computer, because of its high computational complexity and difficulty. FHE boasts a high-security level and therefore is receiving considerable attention as next-generation encryption technology. However, despite being able to process computations on encrypted data, the slow computation speed due to the high computational complexity of FHE technology is an obstacle to practical use. To address this problem, hardware technology that accelerates FHE operations is receiving extensive research attention. This article examines research trends associated with developments in hardware technology focused on accelerating the operations of representative FHE schemes. In addition, the detailed structures of hardware that accelerate the FHE operation are described.

• 전력전자학회논문지
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• 제9권5호
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• pp.467-477
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• 2004

본 논문에서는 극저속 영역에서 서보 전동기 구동 장치의 관성을 추정하는 기법을 제안한다. 대개의 서보 시스템에서 저속 영역의 성능 향상을 위해 사용되는 순시 속도 관측기는 관성계수와 같은 기계계 파라미터의 변동에 민감하다. 이와 같은 문제를 해결하기 위해 방사형 기저 함수망(Radial Basis Function Networks)을 이용하는 전동기관성을 추정기법을 제안한다. 실험을 통하여 제안한 추정기법의 타당성을 검증한다.

• 한국컴퓨터정보학회논문지
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• 제3권1호
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• pp.81-94
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• 1998

영상에서 관심있는 물체의 윤곽선을 추출하기 위해서 Kass등은 Snakes라고 불리우는 능동적 윤곽선 모델(active contour model)을 제안하였다. Snakes 모델은 내부 에너지,영상 에너지, 외부 에너지라는 에너지 함수를 사용하여 물체의 윤곽선을 정의하는 모델로 이 에너지 함수를 최소화함으로써 물체의 윤곽선을 찾을 수 있다 이 모델은 속도가 느리며초기화에 민감하다. 이 문제를 개선하기 위해 Gunn은 두 개의 초기화를 이용하여 정확한 윤곽선을 추출하고 초기화에 덜 민감하도록 하였다. 이 방법은 기존의 다른 방법에 비해 정확한 윤곽선을 추출할 수 있었으나, 속도면 에서는 상당히 효율적이지 못하고 잡음에 민감하였다. 본 논문에서는 이 문제를 해결하기 위하여 snakes을 이루는 각 윤곽점에 8$\times$8크기의 윈도우를 적용하여 윈도우내의 화소에 대해서만 에너지 최소화 알고리즘을 적용하였다.본 논문에서 제안한 방법은 원 영상과 컵 영상의 윤곽선 추출에 적용하였다. 제안한 방법을사용하여 얼굴을 추적하므로써 가상현실등에 응용되고 물체의 움직임 추적에도 응용될 수 있다.

• 감성과학
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• 제17권1호
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• pp.29-38
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• 2014

In recent days, according as ergonomics and aesthetic engineering are important factors in the product market, there is a demand to develop automobile seat and interior designs which are focused on sensitive elements such as aesthetic and comfort features in order to satisfy the sensitive needs of consumers. To meet such demands, car seats are turning into functional and sensitive products that reflect elements of function and entertainment. According to such trends, this research is aimed to develop the illuminating car seat fabric that serve such functions as recognizing and reacting to car environments, which includes sensing over-speed, open doors, and unfastened safety belts through the illuminating car seat fabrics by optical fiber. For this purpose, basic physical properties of optical fiber are analyzed, appropriate weaving and etching technologies are applied, and the woven fabric of optical fiber for car seats are illuminating depend upon car environments. Moreover, the applicable woven fabric of optical fiber is deduced after evaluating the physical properties (such as tensile strength, heatproof, anti-fouling, washable and combustible traits) for the appropriateness of applying the woven fabric of optical fiber to car seats. For this purpose, the woven fabric of optical fiber is covered according to car seat processes; the optical fiber applied to seats is composed that it may be connected to one end of the connector linked to a LED so that it may perform functions like sensing over-speed, open doors, and unfastened safety belts; the sensed signals are transmitted to the control part, and luminescent signals are transmitted to LED.

• 한국멀티미디어학회논문지
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• 제12권10호
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• pp.1374-1385
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• 2009

최근 CPU의 속도는 메모리의 속도에 비해 훨씬 빠르게 향상되었다. 따라서 주기억 장치의 접근이 주기억장치 데이터베이스 시스템의 성능에서 병목현상으로 나타나고 있다. 기억장치 접근 속도를 줄이기 위해 캐시메모리를 이용하지만, 캐시메모리는 요구되는 데이터가 캐시에서 찾을 수 있는 경우에만 기억장치 접근속도를 줄일 수 있다. 본 논문에서는 $CST^*$-트리라는 범위질의를 위한 새로운 캐시 적응 T-트리 색인구조를 제안한다. $CST^*$-트리는 색인 엔트리를 저장하지 않는 축소된 내부노드들을 캐시메모리에 올려 사용함으로써 캐시메모리의 활용도를 높인다. 그리고 인접한 단말노드들과 내부 색인노드들을 링크포인터를 통해 서로 연결함으로써 색인 엔트리들의 순차적 접근을 가능하도록 한다. 본 논문에서는 성능평가를 위한 비용 모델을 개발하고, 이를 이용하여 캐시미스 발생 횟수를 평가하였다. 그 결과 단일키 값 검색에서는 기존의 캐시만을 고려한 CST-트리에 비해 약 20~30%의 캐시미스 발생 횟수가 감소하였고, 범위질의에서는 기존의 범위질의만을 고려한 색인구조인 $T^*$-트리에 비해 약 10~20%의 캐시미스 발생 횟수가 감소하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1074-1079
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• 2011

This paper describes the influence on the nonlinear critical speed results of a specific railway vehicle depending on various constraint conditions. In the roller-rig tests, proper constraints are inevitable to safely hold the test vehicles. Particularly, the test results using KRRI roller-rig are more sensitive to constraint conditions because it is a kind of semi-full car type. In this study, nonlinear critical speed of specific vehicle with regards to several constraint cases were predicted by computational analysis and these results were compared to find the suitable constraint conditions. And also the deviation of semi-full car model from actual full car model was investigated. According to the bifurcation analysis, the nonlinear critical speed are dependent with the constraint condition and car-body yaw motion should be free to achieve more accurate results. And the difference between semi-full and full car model was so small that KRRI's semi-full car model are valid as long as the stability is concerned.