• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.129-133
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• 2014

In this paper, we propose a simple Double random phase encryption (DRPE)-based orthogonal encoding technique for color image encryption. In the proposed orthogonal encoding technique, a color image is decomposed into red, green, and blue components before encryption, and the three components are independently encrypted with DRPE using the same key in order to decrease the complexity of encryption and decryption. Then, the encrypted data are encoded with a Hadamard matrix that has the orthogonal property. The purpose of the proposed orthogonal encoding technique is to improve the security of DRPE using the same key at the cost of a little complexity. The proposed orthogonal encoder consists of simple linear operations, so that it is easy to implement. We also provide the simulation results in order to show the effects of the proposed orthogonal encoding technique.

• 대한전기학회논문지
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• 제39권6호
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• pp.638-648
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• 1990

An effective resolved motion control method of redundant manipulators is proposed to minimize the energy consumption and to increase the dexterity while satisfying the physical actuator constraints. The method employs the neural optimization networks, where the computation of Jacobian matrix is not required. Specifically, end effector movement resulting from each joint differential motion is first separated into orthogonal and tangential components with respect to a given desired trajectory. Then the resolved motion is obtained by neural optimization networks in such a way that 1) linear combination of the orthogonal components should be null 2) linear combination of the tangential components should be the differential length of the desired trajectory, 3) differential joint motion limit is not violated, and 4) weighted sum of the square of each differential joint motion is minimized. Here the weighting factors are controlled by a newly defined joint dexterity measure as the ratio of the tangential and orthogonal components.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.156-159
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• 2008

Proper orthogonal decomposition is a statistical pattern analysis technique for finding the dominant components, called the proper orthogonal modes, in ensembles of spatially distributed data. We present recent ideas based on proper orthogonal decomposition (POD) and detailed experiments that yield new perspectives into the microscale structures. The linearized modeling technique based on POD is very useful to show the principal characteristics of the complex dynamic responses.

• Communications for Statistical Applications and Methods
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• 제27권5호
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• pp.523-533
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• 2020

This paper suggests three available methods for finding nonnegative estimates of variance components of the random effects in mixed models. The three proposed methods based on the concepts of projections are called projection method I, II, and III. Each method derives sums of squares uniquely based on its own method of projections. All the sums of squares in quadratic forms are calculated as the squared lengths of projections of an observation vector; therefore, there is discussion on the decomposition of the observation vector into the sum of orthogonal projections for establishing a projection model. The projection model in matrix form is constructed by ascertaining the orthogonal projections defined on vector subspaces. Nonnegative estimates are then obtained by the projection model where all the coefficient matrices of the effects in the model are orthogonal to each other. Each method provides its own system of linear equations in a different way for the estimation of variance components; however, the estimates are given as the same regardless of the methods, whichever is used. Hartley's synthesis is used as a method for finding the coefficients of variance components.

• 응용통계연구
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• 제19권3호
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• pp.587-598
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• 2006

본 논문에서는 마이크로어레이 (microarray) 자료에 판별분석을 적용 시 나타나는 고차원 및 소표본 문제의 해결방법으로서 직교요인을 새로운 특징변수로 사용한 비모수적 국소선형 로지스틱 판별분석을 제안한다. 제안된 방법은 국소우도에 기반한 것으로서 다범주 판별분석에 적용될 수 있으며, 고려된 직교인자는 주성분 요인, 부분최소제곱 요인, 인자분석 요인 등이다. 대표적인 두 가지 실제 마이크로어레이 자료에 적용한 결과 직교요인들 중에서 부분최소제곱 요인을 특징변수로 사용한 경우 고전적인 통계적 판별분석보다 향상된 분류 능력을 나타내고 있음을 확인하였다.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.144-155
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• 1999

An occupant analysis code SAFE (Safety Analysis For occupant crash Environment) is utilized to simulate and improve the crash performance of an energy absorbing steering system. The safety standard FMVSS 203 is simulated and used for design evaluations . Segments and contact elliposids are utilized to model the bod blocks and the components of the steering system with SAFE. Spring-damper elements and force-deflection characteristics are utilized to model the energy absorbing components such as the plate and the polyacetal molding. The plate absorbs the impact energy through tensile deformation . Whereas, the polyacetal molding absorbs the impact energy through compression. the body block test is carried out to validate tie simulation model, and real component tests are performed to extract the force-deflection curves . After the model is validated , the parameter study is carried out to evaluate the crash performance of the energy absorbing components. A performance measure is defined for the parameter study. Using the results of the parameter study and managing the orthogonal arrays, optimum design values of energy absorbing components are determined to minize the occupant injury.

• Wind and Structures
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• 제38권4호
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• pp.277-293
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• 2024

The recorded thunderstorm winds at a point contain tri-directional components. The probabilistic characteristics of such recorded winds in terms of instantaneous mean wind speed and direction, and the probability distribution and the time-frequency dependent crossed and non-crossed power spectral density functions for the high-frequency fluctuating wind components are unclear. In the present study, we analyze the recorded tri-directional thunderstorm wind components by separating the recorded winds in terms of low-frequency time-varying mean wind speed and high-frequency fluctuating wind components in the alongwind direction and two orthogonal crosswind directions. We determine the time-varying mean wind speed and direction defined by azimuth and elevation angles, and analyze the spectra of high-frequency wind components in three orthogonal directions using continuous wavelet transforms. Additionally, we evaluate the coherence between each pair of fluctuating winds. Based on the analysis results, we develop empirical spectral models and lagged coherence models for the tri-directional fluctuating wind components, and we indicate that the fluctuating wind components can be treated as Gaussian. We show how they can be used to generate time histories of the tri-directional thunderstorm winds.

• 대한기계학회논문집A
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• 제29권9호
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• pp.1161-1168
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• 2005

As a result of vehicle maintenance of rocker arm shaft for 4-cylinder SOHC engine, failure analysis of rocker arm shaft is needed. Because more than $30\%$ of vehicles investigated have been fractured. Failure analysis is classified into an naked eyes, microscope and X-ray fractography etc. It can predict applied load as well as load type. These methods are applicable to components with simple boundary condition but aren't applicable to components with complex boundary condition. The existing fractography don't catch hold of failure boundary condition quantitatively. Especially, in case that the components isn't fractured at same position. We must determine the most dangerous failure boundary condition to evaluate their operation mechanism. The effect of various factors on response should be estimated to solve this statical problem. This study presents the most dangerous failure boundary condition of rocker arm shaft using orthogonal array and ANOVA in order to assure its robustness.

• 한국생산제조학회지
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• 제19권1호
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• pp.42-49
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• 2010

In general, the direct experimental approach to study machining processes is expensive and time consuming, especially when a wide range of parameters are included: tool, geometry, materials, cutting conditions, etc. The aim of this study is to verify the effectiveness of finite element method for orthogonal cutting process by comparing the simulated cutting forces with measured results. Two commercialized finite element codes $AdvantEdge^{TM}$ and Deform-$2D^{TM}$ have been used to simulate the cutting forces in orthogonal cutting process. In this paper, estimated cutting and feed force components are compared with experimental results for different two materials. As a result, it has been found that FEM simulation is effective for understanding and predicting the orthogonal cutting process although some improvements on friction model and remeshing process are needed.

• Communications for Statistical Applications and Methods
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• 제26권4호
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• pp.337-346
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• 2019

This paper discusses a method for obtaining nonnegative estimates for variance components in a random effects model. A variance component should be positive by definition. Nevertheless, estimates of variance components are sometimes given as negative values, which is not desirable. The proposed method is based on two basic ideas. One is the identification of the orthogonal vector subspaces according to factors and the other is to ascertain the projection in each orthogonal vector subspace. Hence, an observation vector can be denoted by the sum of projections. The method suggested here always produces nonnegative estimates using projections. Hartley's synthesis is used for the calculation of expected values of quadratic forms. It also discusses how to set up a residual model for each projection.