• Journal of the Korea Society of Computer and Information
• /
• v.10 no.5 s.37
• /
• pp.77-86
• /
• 2005

In this paper, we designed a learning algorithm of LVQ that extracts classification errors and learns ones and improves classification performance. The proposed LVQ learning algorithm is the learning Networks which is use SOM to learn initial reference vectors and out-star learning algorithm to determine the class of the output neurons of LVQ. To extract pattern vectors which cause classification errors, we proposed the error-cause condition, which uses that condition and constructed the pattern vector space which consists of the input pattern vectors that cause the classification errors and learned these pattern vectors , and improved performance of the pattern classification. To prove the performance of the proposed learning algorithm, the simulation is performed by using training vectors and test vectors that are Fisher' Iris data and EMG data, and classification performance of the proposed learning method is compared with ones of the conventional LVQ, and it was a confirmation that the proposed learning method is more successful classification than the conventional classification.

• Journal of Broadcast Engineering
• /
• v.18 no.4
• /
• pp.589-598
• /
• 2013

In order to understand 3D visual fatigue, it is necessary to examine the visual fatigue induced by camera parameters as well as that induced by a pre-existing 3D content. In the present study, we examined the effects of camera parameters, such as roll misalignment error, shooting distance and vergence condition on 3D visual fatigue and we modelled it. The results indicate that roll misalignment error, shooting distance and vergence condition affect 3D visual fatigue and the effect of roll misalignment error on 3D visual fatigue is evident specifically when screen disparity is relatively small.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 1997.11a
• /
• pp.183-188
• /
• 1997

안구의 운동은 시각 환경에서의 진행중인 정보처리와 관련된 지각적, 인지적 과정을 밀접히 반영하는 중요한 지표로서, 특히 공간 지각과의 상관은 비교적 명확히 확립되어 있다. 본 연구는 공간지각에 관여하는 안구운동의 특성을 파악하여, 공간지각을 반영하는 안구운동 지표를 개발한다는 목표 아래, 피험자가 느끼는 공간의 확장과 축소의 특성을 이중도약과제(double-step paraeigm)를 사용하여 관찰한 것이다. 이중도약과제는 도약(saccadic)안구운동의 오차를 유발시키는 실험기법으로, 두개의 시각자극을 하나씩 연속적으로 보여주되, 두번째 자극은 안구운동이 일어나는 도중에 제시하는 것으로서, 인위적으로 왜곡된 공간에 대한 피험자의 공간적응을 관찰하는데 사용되었다. 이 과제는 다시 자극의 이차도약 방향에 따라 축소감 조건과 확장감 조건으로 나뉘었고, 머리운동의 역할을 판별하기 위해 머리를 고정한 조건과 머리를 자유롭게한 조건으로 분류되었다. 그 결과 머리가 고정된 상태에서는 축소감 조건에 대한 적응이 확장감 조건에서보다 더 빨리 일어나고, 그 적응후의 시선이동의 변화량에서도 축소감 조건이 더 크게 나타났다. 또한 머리를 자유롭게 할 공간 지각의 정확성이 증가하며, 축소감과 확장감 경험속도의 차이가 약 49.2%까지 해소되었으나, 여전히 축소감의 경험이 더 잘 일어났다.

• Journal of the Korean Vacuum Society
• /
• v.20 no.6
• /
• pp.387-394
• /
• 2011

Standard devices and procedures for measuring the pumping speed, one of the most important parameters indicating the operation performance of the vacuum pump, have been developed and widely utilized. Though the standard system has a firm theoretical basis, it is, sometimes, inevitable to alter something in the system for a practical purpose compared with ideal conditions, which may lead to a large measurement error. In this paper, characteristics and systematic errors of various ideal or practical schemes for measuring the pumping speed are analyzed, and compensation terms are proposed.

• Journal of Advanced Navigation Technology
• /
• v.20 no.5
• /
• pp.425-432
• /
• 2016

When user estimates user's position, GPS positions can be obtained from the navigation message transmitted from the GPS. However, the broadcast ephemeris cannot be used in the applications required high-level accuracies because it can cause errors of several meters. To correct satellite positions and clocks, user can use RTS corrections provided by IGS. In this paper, the accuracy of broadcast and RTS corrections are analyzed by comparing with the IGS final for 3-months. The RTS errors are analyzed for each user's locations and satellite blocks. The correlations between errors and shadow condition, and solar and geomagnetic activities are analyzed. The latency is applied to the RTS corrections, and these are extrapolated by polynomial. Then, the extrapolated RTS are compared with true RTS. The single-day performances of the PPP by broadcast ephemeris and RTS corrected ephemeris are analyzed. As a result, RTS 3D orbit and clock errors are 1/20 and 1/3 less than broadcast ephemeris errors. 3D positioning error of the RTS is 1/5 less than that of broadcast ephemeris.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05c
• /
• pp.245-248
• /
• 2003

저온동시소성 세라믹으로 제작된 모듈을 고주파 대역에 적용할 경우 dimension의 오차는 모듈 특성의 오차를 유발시킨다. Constrained sintering 기술은 XY 방향의 수축을 억제시킴으로써 세라믹 소결체의 dimensional tolerance를 향상시키기 위하여 개발된 기술이다. LTCC의 소성온도에서는 수축하지 않는 비소성층을 LTCC 적층체의 위 아래에 함께 적층시킴으로써 XY 방향의 수축은 기계적으로 억제되며, 두께 방향으로만 수축이 일어난다. 본 연구에서는 LTCC 기판을 constrained sintering 방법으로 소성하고, 그 특성값을 일반적인 소성방법으로 제작하였을 때와 비교하였다. 알루미나 테잎의 제조조건 빛 적층조건을 변화시켜 이에 따른 면수축 제어 특성의 변화를 고찰하였다. 실험결과 알루미나 테잎의 고형분 용량과 부착층의 두께가 면수축 제어를 위하여 고려되어야할 주요 인자임을 확인할 수 있었다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.19 no.2
• /
• pp.445-452
• /
• 2024

This paper analyzes the navigation error for each rotational motion in order to design an optimal rotation sequence, which is a key technology in the rotational inertial navigation. Rotational inertial navigation system is designed to cancel out navigation errors caused by inertial sensor errors by periodically rotating the inertial measurement unit. A properly sequenced rotational motion cancels out the maximum amount of navigation error and is known as an optimal rotation sequence. To design such an optimal turning procedure, this paper identifies the feasible rotational motions that can be implemented in a rotational inertial navigation system and analyzes the navigation error introduced by each rotational motion. In addition, by analyzing the characteristics of the navigation error generated during a rotation sequence in combination, this paper presents the conditions for designing an optimal rotation sequence.

• Journal of Aerospace System Engineering
• /
• v.12 no.3
• /
• pp.9-17
• /
• 2018

For Earth observation, a small satellite camera has relatively weak structural stability compared to medium-sized satellite, resulting in misalignment of optical components due to severe launching and space environments. These alignment errors can deteriorate the optical performance of satellite cameras. In this study, we proposed a 3-axis focus mechanism to compensate misalignment in a small satellite camera. This mechanism consists of three piezo-electric actuators to perform x-axis and y-axis tilt with de-space compensation. Design requirements for the focus mechanism were derived from the design of the Schmidt-Cassegrain target optical system. To compensate the misalignment of the secondary mirror (M2), the focus mechanism was installed just behind the M2 to control the 3-axis movement of M2. In this case, flexure design with Box-Behnken test plan was used to minimize optical degradation due to wave front error. The wave front error was analyzed using ANSYS. The fabricated focus mechanism demonstrated excellent servo performance in experiments with PID servo control.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1987.05a
• /
• pp.7.3-8
• /
• 1987

청성뇌간 유발반응이 Juwett 및 Sohmer와 Feinmesser에 의하여 보고된 이래 타각적 청력검사로서 임상적응용에까지 이르렀다. 타각적 청력검사는 반응역치와 청각역치의 오차가 적어야 하며 주파수별로 역치측정이 가능하여야 하며 개인차가 적고 반응의 재현성이 높아야 되며 반응의 판정이 용이해야 함이 필요조건으로서 이러한 조건이 피검자의 수면상태하에서도 충족되어야 한다. 저자들은 정상 성인 청력자를 대상으로 sedation전후의 ABR에 대한 latency 및 amplitude를 중심으로 관찰하여 다음과 같은 결과를 얻었다. 1) Sedative의 사용에 있어서 amplitude및 latency의 차이는 없었다. 2) Sedative의 사용에는 무관하게 low frequency filter에서 high frequency filter보다 voltage의 유의한 차가 있었다.

• Journal of the Society of Naval Architects of Korea
• /
• v.34 no.1
• /
• pp.41-49
• /
• 1997

Computational results from Navier-Stokes equations are presented for the Stokes-wave/flat-plate boundary-layer and wake for small wave steepness(Ak=0.01), including exact and approximate treatments of the viscous free-surface boundary conditions. The macro-scale flow indicate that the variations of the external-flow pressure gradients cause acceleration or deceleration of the streamwise velocity component and alternating direction of the cross flow. Remarkably, the wake displays a greater response, i.e., a bias with regard to favorable as compared to adverse pressure gradients. The micro-scale flow indicates that the free-surface boundary conditions have a profound influence over the boundary layer and near/intermediate wake. Order-of-magnitude estimates are conformed to the computational results. And appreciable errors are introduced through approximations to the free-surface boundary conditions.