• 한국정보처리학회논문지
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• 제4권12호
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• pp.3078-3087
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• 1997

컴퓨터 통신망을 통한 정보전송에 있어 정보보호의 문제는 매우 중요하며 이를 제공하기 위한 정보보호 시스템 개발이 여러 방면에서 이루어지고 있다. 이러한 정보보호 시스템 개발시 비밀키의 분배 및 상호 인중은 정보 보호의 필수 불가결한 요소이며, 이에 대한 많은 방법들이 제시되어 왔다. 그러나 이러한 많은 방법들은 통신 프로토콜을 고려하지 않은 경우가 많아 실제 통신 환경에 적용하기가 쉽지 않았다. 본 논문에서는 패킷 통신의 하나인 X.25 프로토콜을 중심으로 프로토콜이 갖는 특성을 유지하면서 키 분배 및 인증을 수행하는 방법을 제 안하였으며, 선택적으로 비밀 통신을 할 수 있는 방법을 함께 제안함으로써 정보보호 시스템이 범용성을 갖도록 하였다.

• Journal of information and communication convergence engineering
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• 제7권2호
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• pp.193-198
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• 2009

The H.264/ AVC video coding standard supports the intra prediction with various block sizes for luma component and a 8x8 block size for chroma components. This new feature of H.264/AVC offers a considerably higher improvement in coding efficiency compared to previous compression standards. In order to achieve this, H.264/AVC uses the Rate-distortion optimization (RDO) technique to select the best intra prediction mode for each block size, and it brings about the drastic increase of the computation complexity of H.264 encoder. In this paper, a fast block size decision algorithm is proposed to reduce the computation complexity of the intra prediction in H.264/AVC. The proposed algorithm computes the smoothness based on AC and DC coefficient energy for macroblocks and compares with the nonparametric criteria which is determined by considering information on neighbor blocks already reconstructed, so that deciding the best probable block size for the intra prediction. Also, the use of non-parametric criteria makes the performance of intra-coding not be dependent on types of video sequences. The experimental results show that the proposed algorithm is able to reduce up to 30% of the whole encoding time with a negligible loss in PSNR and bitrates and provides the stable performance regardless types of video sequences.

• 한국음향학회지
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• 제16권5호
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• pp.83-91
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• 1997

원자로의 구조적 건전성을 확보하고 사고를 미연에 방지하기 위해서 중성자 잡음 신호를 이용한 진동 감시에는 주기성 도표(periodogram), 평균주기성도표(averaged periodobram), Blackman-Tukey 스펙트럼 추정 등을 이용하고 있으나 본 논문에서는 통계적인 비편향성(unbaised), 일치성(consistency), 효율성(efficiency), 충족성(minimum lower bound)을 고려한 파라미터 모델링 방법 중 AR 모델을 이용하여 원자로 구조물의 최적의 파라미터를 추정하고 진동 감시에 필요한 스펙트럼 분석의 해상도를 높였다. 특히 논문에서는 차수 선정에서 AR 모델의 적절한 차수선정(order selection)을 위하여 자기상관의 lag value을 이용하였다. AR 방법중 Burg 방법이 원자로 구조물의 고유진동수를 추적하는데 가장 효과적이다.

• 전자공학회논문지 IE
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• 제45권3호
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• pp.42-49
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• 2008

본 논문은 CDMA2000, W-CDMA, W-LAN 채널의 다중경로 방식을 사용하는 스마트 안테나 시스템에서 빔포밍 이득과 다이버시티 이득을 신호 환경에 따라 선택하는 새로운 빔형성 알고리즘을 제안하였다. 본 논문에서는 정량화된 실험치를 근거로 하여 어느 시점에서 다이버시티 이득을 얻을 것인지에 대한 판단 기준을 제시하였다. 제안된 방법은 퍼짐각이 존재할 때 두 개의 고유벡터를 이용하는 기존의 방법보다 더 좋은 성능을 제시함을 알 수 있었다. 다양한 실험을 통해 성능분석 결과 제안 방법이 기존의 알고리즘보다 $3{\sim}4$배 정도 성능이 우수함을 확인할 수 있었다.

• 한국지열·수열에너지학회논문집
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• 제14권2호
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• pp.15-22
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• 2018

As heat pump application has been extending to residential, commercial, and industrial fields, the heat pump should have many operation modes. It is required to optimize refrigerant charge amount at all operation modes in order to enhance the annual performance of heat pumps. In this study, the performance analysis of the heat pump which has cooling, heating, cooling-hot water, heating-hot water, and hot water modes was executed with the variation of refrigerant charge amount. As the refrigerant charge amount changed, the maximum COPs of the heat pump at different operation modes were changed within ${\pm}10%$. Therefore, it is highly recommended to select optimum charge amount for the heat pump based on the analysis of annual load for each operation modes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.106-109
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• 2014

In order to obtain dynamic behaviors of complex structures, it demands large amounts computational cost and time to perform the numerical analysis. The model reduction method helps these problems by dividing the full model into primary and unnecessary parts. In this research, we perform the modal analysis using the dynamic substructuring method, which is one of the model reduction methods, in order to obtain the dynamic characteristics of the cylindrical structures efficiently. To select the master degrees of freedom (dofs), we consider the mode shapes of the cylindrical structures. And then, we identify the validity of the dynamic substructuring method by applying the method to the simple cylinder and core support barrel (CSB) which is one of the reactor internals with the cylindrical shape. The results demonstrate that the dynamic characteristics from the dynamic substructuring method are well matched with the original method.

• Journal of Biosystems Engineering
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• 제18권4호
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• pp.328-343
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• 1993

To control depth of tractor implement, an automatic depth control system based upon microcomputer was developed. This system consists of data aquisition system to measure and to record travel speed, draft and depth of the implement, hydraulic system to control the implement depth and 3-point hitch to attach the implement. Program, written in C language, was able to select position control, draft control and mixed control. To analyze parameters affecting this system, the performance of the system was evaluated through use of computer simulation and verified in soil bin experiments. 3-point hitch was lifted by hydraulic pressure and lowered by implement weight. Dead band was one of the important factors which affect the stability and the accuracy of the system. The system became unstable when the flow rate was increased or when the dead band was decreased. The position control mode with on-off control showed the great ability to control the implement at the given plowing depth. With the draft control, the tractor load could be reduced, however the plowing depth was changed unexpectedly when the soil was hard and inconsistent. The mixed control could improve the performance of the system to maintain the plowing depth without overload of the tractor.

• 한국작물학회지
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• 제46권4호
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• pp.261-265
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• 2001

This study was carried out to select randomly amplified polymorphic DNA (RAPD) markers associated with grain weight of a large-grain mutant, Hyacp 39-26-1, derived from anther culture of a rice cultivar, 'Hwayeongbyeo'. The segregation mode for grain weight in an F$_2$ population from a cross, 'Hwayeongbyeo/Hyacp 39-26-1', showed a nearly normal distribution. One hundred and ninety-one F$_2$plants ranged from 21.8 g to 34.7 g in 1,000-grain weight with a mean of 26.8 g. Five hundred and twenty primers were used to detect the RAPD markers associated with the grain weight of the large-grain mutant. Of these primers, 54 primers showed polymorphism between 'Hwayeongbyeo' and 'Hyacp 39-26-1'. Four RAPD markers (OPB18, OPH07, OPT20, and OPX20) were significantly related to the grain weight of twenty one F$_3$ lines derived from the cross, 'Hwayeongbyeo/Hyacp 39-26-1'. This RAPD marker could facilitate the early and efficient selection of high-yield lines through improvement of grain weight in rice.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.162-168
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• 2008

A design objective for variable stability flight control system is to develop a controller of in-flight simulation capability that forces the aircraft being flown to follow the dynamics of other aircraft. This paper presents a model-following variable stability control system (VSS) for in-flight simulation which consists of feedforward and feedback control laws, the aircraft dynamic model to be simulated, and switching and fader logics to reduce the transient effect between two aircraft dynamics. The separate design techniques for feedforward and feedback control law proposals are based on model matching and augmented linear quadratic (LQ) techniques. The system allows pilots to select and engage VSS mode, and when deselected, the aircraft reverts to the baseline flight control system. Both the baseline flight control laws and VSS control laws are computed continuously during flight. Initialization of the state values are necessary to prevent instability, since VSS control laws have integrators and filters in longitudinal, and lateral/directional axes. This paper demonstrates and validates the effectiveness and quality of VSS with F-16 models embedded in T-50 in-flight simulation aircraft.

• 한국게임학회 논문지
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• 제1권1호
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• pp.55-60
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• 2001

With rapid development of graphic hardware, researches on Virtual Reality and 3D Games have received more attention than before. For more realistic 3D graphic scene, objects were to be presented with lots of polygons and the number of objects shown in a scene was remarkably increased. Therefore, for effective visualization of large polygon models like this, view-frustum culling method, that visualizes only objects shown in the screen, has been widely used. In general, the bounding boxes that include objects are generated firstly, and the boxes are intersected with view-frustum to check whether object is in the visible area or not. Recently, an algorithm that can check in-out test of objects using OpenGL's selection mode, which is originally used to select the objects in the screen, is suggested. This algorithm is fast because it can use hardware acceleration. In this study, by implementing and applying this algorithm to large polygon models, we showed the efficiency of OpenGL assisted View-Frustum Culling algorithm. If this algorithm is applied to 3D games that have to process more complicated characters and landscapes, performance improvement can be expected.