• International Journal of Aeronautical and Space Sciences
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• 제1권2호
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• pp.9-16
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• 2000

For aerodynamic design of missile bodies of non-circular cross-section, the combination of the slender body theory and the cross-flow analogy can hardly be applied owing to the lack of experimental data. An alternative is to utilize the Euler solution in the design stage. For enhanced accuracy, however, an adequate viscous correction is necessary to the Euler solution. In this work, such a procedure is examined to compensate the viscous effect by utilizing the concept of proportionality factor in cross-flow analogy. Predictions of aerodynamic coefficients combining the Euler solution and the viscous correction via proportionality factor are made for a missile body of elliptic cross-section. Results indicate that the present approach can be adopted in designing missile bodies of non-circular cross-sections.

• Smart Structures and Systems
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• 제14권3호
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• pp.419-444
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• 2014

Within this paper a new approach for early damage detection in rotor blades of wind energy converters is presented, which is shown to have a more sensitive reaction to damage than eigenfrequency-based methods. The new approach is based on the extension of Gasch's proportionality method, according to which maximum oscillation velocity and maximum stress are proportional by a factor, which describes the dynamic behavior of the structure. A change in the proportionality factor can be used as damage indicator. In addition, a novel deflection sensor was developed, which was specifically designed for use in wind turbine rotor blades. This deflection sensor was used during the experimental tests conducted for the measurement of the blade deflection. The method was applied on numerical models for different damage cases and damage extents. Additionally, the method and the sensing concept were applied on a real 50.8 m blade during a fatigue test in the edgewise direction. During the test, a damage of 1.5 m length was induced on the upper trailing edge bondline. Both the initial damage and the increase of its length were successfully detected by the decrease of the proportionality factor. This decrease coincided significantly with the decrease of the factor calculated from the numerical analyses.

• Journal of Communications and Networks
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• 제17권3호
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• pp.213-220
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• 2015

In this paper, we present a reliability-based iterative proportionality-logic decoding algorithm for two classes of structured low-density parity-check (LDPC) codes. The main contributions of this paper include: 1) Syndrome messages instead of extrinsic messages are processed and exchanged between variable nodes and check nodes, which can reduce the decoding complexity; 2) a more flexible decision mechanism is developed in which the decision threshold can be self-adjusted during the iterative process. Such decision mechanism is particularly effective for decoding the majority-logic decodable codes; 3) only part of the variable nodes satisfying the pre-designed criterion are involved for the presented algorithm, which is in the proportionality-logic sense and can further reduce the computational complexity. Simulation results show that, when combined with factor correction techniques and appropriate proportionality parameter, the presented algorithm performs well and can achieve fast decoding convergence rate while maintaining relative low decoding complexity, especially for small quantized levels (3-4 bits). The presented algorithm provides a candidate for those application scenarios where the memory load and the energy consumption are extremely constrained.

• 전자공학회논문지D
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• 제35D권2호
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• pp.93-100
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• 1998

In this paper we analyze the effect of nonlinear gain on laser modulation characteristics applying a small-signal analysis to the rate equation which includes a nonlinear gain term. Also we analyze the resonance frequency and the damping factor which determine laser modulation characteristics, define K factor which is the proportionality factor between resonance frequency and damping factor, and conclude that the decrease in K factor is due to increases in differential gain and no correlation between K factor and nonlinear gain is identified.

• 대한조선학회논문집
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• 제53권3호
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• pp.237-248
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• 2016

As OPB and IPB moment-induced fatigue damage on mooring chain links were reported for a offloading buoy, verification of OPB and IPB fatigue has been a key engineering item in offshore structure mooring design. Mathematical and physical features of the conventional approach which was mainly explained in BV guideline are reviewed and disadvantages of the conventional approach are addressed in terms of stress proportionality and nonlinearity of OPB and IPB moments. In order to eradicate these disadvantages, a novel approach is newly proposed which is able to dispel apprehension on stress proportionality and is not dependent of nonlinearities of OPB and IPB moments. Significant differences between two approaches are suggested by comparing relations of OPB moment versus OPB interlink angle and IPB moment versus IPB interlink angle. For periodic OPB tension angle processes having three different OPB angle ranges with a simple irregular tension process, fatigue damage calculation reveals that OPB moment-induced fatigue damage has dominant portion to total fatigue damage. Comparative studies between two approaches also show that the conventional approach based on BV guideline predicts fatigue damage far conservatively since it assume unrealistic high stress concentration factor for tension load. Meanwhile IPB moment-induced fatigue damage is negligible compared to tension-induced fatigue damage.

• 한국과학교육학회지
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• 제24권5호
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• pp.987-995
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• 2004

이 연구에서는 초등학교 5학년을 대상으로 인지 수준 및 정보 처리 유형에 따른 비례, 보상 문제 해결 정도를 알아보고, 문제 해결 전략 및 해결 과정에서의 주요 오류를 분석하였다. 연구 결과 인지 수준이 구체적 조작 중기 이상이면 곤란도가 낮거나 높은 비례 문제와 곤란도가 낮은 보상 문제를 해결할 수 있었고, 곤란도가 높은 보상 문제는 대부분의 학생들이 문제 해결에 실패하였다. 정보 처리 능력이 높을수록 문제 해결 시간이 짧아지는 경향을 보였다. 비례, 보상 문제를 해결할 때는 변화 요인, building-up과 같은 직관적인 전략과 곱하기 연산과 같은 형식적인 전략을 주로 사용하였다. 비례, 보상 문제를 해결 과정에서 나타나는 주요 오류는 스키마 지식, 절차지식, 전략 지식에서 나타났으며, 스키마 지식의 결여로 기존에 사용했던 비례 전략을 적용하려는 Einstellung 현상이 뚜렷하였다. 특히 동일한 스키마 지식이 적용되는 문항에서 곤란도가 높아지면 스키마 지식의 오류로 인하여 문제 해결에 실패하는 경우가 많았다. 따라서, 비례, 보상 논리 문제 해결력의 향상을 위해서는 동일한 스키마 지식이 요구되는 구조와 곤란도가 다양한 문제 해결 경험의 제공이 필요할 것이다.

• 한국정밀공학회지
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• 제18권6호
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• pp.59-66
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• 2001

Fatigue strength of the welding structure is governed by the residual stress at the weldment toe and static tensile overloads were known as relieving the residual stresses. In this study, static tensile overloads were applied to the welding structures which caused the relief of residual stresses. The amount of residual stress relief was found as proportional to the change of fatigue limit at the given conditions. Based on the fact of the proportionality between the change of fatigue limit and that of residual stress, simple measurement technique is proposed. Modified stress-life curves base on proposed technique gave good agreement with test results.

• The Journal of the Acoustical Society of Korea
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• 제15권1E호
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• pp.59-64
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• 1996

When the input-output record is available, the identification of a bilinear system is considered. It is assumed that the input is noise free and the output is contaminated by an additive noise. It is further assumed that the covariance matrix of the noise is known up to a factor of proportionality. The extended generalized total least squares (e-GTLS) method is proposed as one of the consistent estimators of the bilinear system parameters. Considering that the input is noise-free and that bilinear system equation is linear with respect to the system parameters, we extend the GTLS problem. The extended GTLS problem is reduced to an unconstrained minimization problem, and is solved by the Newton-Raphson method. We compare the GTLS method and the e-GTLS method in the point of the accuracy of the estimated system parameters.

• 대한기계학회논문집B
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• 제29권1호
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• pp.131-138
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• 2005

Thermo-osmosis of liquids in a microscale channel is investigated by theoretical and simulation study. From the basic set of conservation equations, the temperature and velocity distributions are derived in the function of the given temperatures and pressure gradient. The pressure gradient for a given temperature gradient is then obtained by the molecular simulation. It is shown that the temperature gradient tangential to the surface induces the pressure gradient and thus the flow in the interfacial region between the liquid and channel surface. The thermo-osmotic flow is proportional to the applied temperature gradient, and the factor of proportionality depends on temperature and intermolecular potential. The origin and characteristics of the phenomenon are discussed in molecular details.

• 한국실내디자인학회논문집
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• 제38호
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• pp.233-240
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• 2003

The purpose of this study was to find the coordination trend of the Image of the color and object from the department show-window display locating in the kangnam area. The result of this study were summarized as following: 1) Show window display determinating the first image of department-store marketing service, playing the role of visual marketing provides the valuable impressions with shoppers in the times of sensibility, 2) In contemporary recognition of "Design is namely culture", show window display proceeds on the direction of concrete and practical presentation of merchandise as many customers are pursuing the high graded luxury brands while their life styles change. 3) Main concept is represented by the coordinated fashion goods on the mannequin or the body and the main theme is displayed variously in the circumferential area or on the articles with the abstract and concrete objects of diverse forms of dominant color and accent color conveying the seasonal theme precisely. 4) The compositive element of color Is the decisive factor of the visual sense of space In the coordination-trends of show window display specially representing the seasonal theme or the intentional messages and conduces to the psychological and mental desire in human and the circumstances, 5) Following the color, the compositive element of object presents the concrete image of theme or the abstract and geometrical sense of space besides the visual sense of space and shows the proportionality and the activity in displaying the show window space.dow space.