• International Journal of Reliability and Applications
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• 제15권1호
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• pp.23-50
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• 2014

This paper deals with formulation of optimum multi-objective modified step-stress accelerated life test (ALT) plan for Burr type-XII distribution under type-I censoring. Since it is impractical to estimate only one objective parameter after conducting costly ALT tests; also, it is not desirable to assume instantaneous changes in stress levels because of limited capacity of test equipments and the presence of undesirable failure modes, therefore, an optimum multi-objective modified step-stress ALT plan has been designed. The optimal test plan consists in determining the optimum low stress level and optimal time at which stress starts linearly increasing from low stress by minimizing the weighted sum of the asymptotic variances of the maximum likelihood estimator of quantile lifetimes at design constant stress. The method developed has been illustrated using an example. Sensitivity analysis has been carried out. Comparative study has also been done to highlight the merits of the proposed model.

• 한국군사과학기술학회지
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• 제21권5호
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• pp.614-622
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• 2018

Based on army operating road profile, the endurance test of military vehicle aims to reproduce the similar loading conditions with mixture of proving ground tracks. It is so called as endurance test mode and its optimal generation is important to meet high reliability of endurance test. In this paper, proving ground optimization is proposed to achieve a close match to the target profile. Several performance measures such as torque-revolution counts or transmission ratio for the powertrain system can be considered as one of the objective functions. However, the one-side optimal endurance test mode may give the poor solution in the whole system point of view. To incorporate several goals simultaneously, this paper employs multi-objective optimization technique to generate endurance test mode. One of the most widely used method, weighted-sum method is applied here and the case study is discussed.

• 펄프종이기술
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• 제48권1호
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• pp.19-26
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• 2016

In the consumer products industry, it has been highly desirable to develop objective test methods to replace subjective evaluation methods. In developing an objective test method, subjective evaluation data should be on a linear scale. According to Thurstone's theory of comparative judgment, a%-preference from a paired-comparison test can be converted to a linear-scale value. The required number (N) of paired-comparison tests increases dramatically as the number of products increases. This problem should be solved by classifying the total products into several subgroups consisting of 3-4 products in each group. By doing so, it can not only significantly reduce the number of required paired-comparison tests, but it can also obtain more reliable, reproducible data.

• 한국전문물리치료학회지
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• 제14권4호
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• pp.7-13
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• 2007

The purpose of this study was to investigate correlations among objective measurements of spasticity in patients with brain lesions. Thirty-two stroke and traumatic brain injury subjects participated in the study. Spasticity was quantified using the knee first flexion angle, relaxation index obtained from a pendulum drop test, and the amplitude of a knee tendon reflex test. Pearson's product correlation coefficient was used to examine relationships among these measurements of spasticity. There was a significant positive correlation between the relaxation index and knee first flexion angle in patients with brain lesions (r=.895, p<.01). There was also significant negative correlation between the amplitude of knee tendon reflex and relaxation index (r=-.612, p<.01), and between amplitude and knee first flexion angle (r=-.537, p<.01). Thus, it is possible to use the knee first flexion angle as an objective measure of spasticity, rather than relaxation index, which is more complicated to obtain. Further studies are needed to explore the effects of functional improvement and long-lasting carryover effects of spasticity using a simple objective measure such as the knee first flexion angle from a pendulum test.

• 한국산학기술학회논문지
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• 제17권5호
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• pp.548-556
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• 2016

노년기의 인지-언어적 변화는 일상생활의 불편함을 초래할 뿐 아니라 신경학적 질환의 주요 지표가 될 수 있다. 본 연구에서는 정상 노년층의 인지-언어 능력에 대한 주관적 및 객관적 평가 간의 상관성을 분석하고 인지-언어 능력의 예측 변인을 알아보았다. 이를 위해 2015년 7월부터 2016년 2월까지 만 65세 이상 정상 노인 63명과 이들의 정보제공자 63명을 대상으로 인지-언어 능력에 대한 자기 보고형 및 정보제공자 보고형 주관적 평가(ISCOLE)와 객관적 평가(CAPTBI)를 시행하였다. 그 결과, 첫째, 노인 및 정보제공자 집단 간에 주관적 평가의 차이는 유의하지 않았다. 둘째, 노인 집단은 8개, 정보제공자 집단은 15개 영역에서 주-객관적 평가 간에 유의한 상관성을 보였다. 셋째, 문제해결력 등은 정보제공자 보고형의 언어능력이, 그리고 집행기능과 언어능력은 정보제공자 보고형의 기억력이 주요 예측 변인이었다. 본 연구를 통해 인지-언어 능력에 대한 주-객관적 평가 간 상관성에 있어 노인 및 정보제공자 집단이 하위 영역별로 차이를 보이며, 정보제공자 집단의 주관적 평가가 더 많은 영역에서 객관적 평가와 상관성이 있음을 알 수 있었다. 이는 정상 노년층을 대상으로 한 인지-언어 능력의 평가 및 예방적 중재 시 적극 활용될 수 있을 것이다.

• 전자공학회논문지B
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• 제30B권10호
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• pp.42-49
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• 1993

In this paper, we evaluate the quality of synthesized speech by rule using the LPC CD as a objective measure, and then compare the test result with the subjective one. Speech used for the test consists of 108 words which are selected by word construction method using Korean attribute and frequency distribution, synthesized by demi-syllable rule. By evaluating the quality of synthesized speech by reule objectively, we have tried to resolve the problems such as lots of evaluation time, expansion of test scale, and variables of analysis result arised by subjective measure. We have, also, proved the validity of the objective test using the LPC CD, by comparing intelligibility which is the index for the subjective quality evaluation of synthesized speech by rule with MOS. From this results, we can provide a guide for quality assessment that would be useful in the R&D of synthesis method and the commercial products using synthesized speech.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.367-374
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• 2005

This paper proposes a sound quality index to evaluate the vehicle interior noise. The index was developed using a correlation analysis of an objective measurement and a subjective evaluation data. First, the objective set of measurements was obtained at two specified driving conditions. One is from a wide-open test condition and the other is from a constant-speed test condition. At the same time, subjective evaluation was carried out using a score of ten scale where 17 test engineers participated in the experiment. The correlation analysis between the psycho-acoustic parameters derived from the objective measurement and the subjective evaluation was performed. The most critical factors at both test conditions were determined, and the corresponding equations for the sound quality were obtained from the multiple factor regression method. Finally, a comparative work between previous index and present index was performed to validate the effectiveness of the proposed index.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1736-1740
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• 2003

There have been various studies to find out the correlation between subjective and objective evaluation ride comfort in vehicle. To be proper, subjective evaluation considers the signal pattern of vibration generated by vehicle. In this study, driving test is carried out to extract the correlation between subjective evaluation by subjects and vibration signals measured on the seat when a test vehicle is passing over test bumpers, which have two sorts of width change and height change respectively. A unique reference bumper is used to be compared with the relative comfort of test bumpers.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.611-616
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• 2003

The headphone is regarded as the most effective means for reproducing 3-dimentional virtual sound due to its channel separation property. However, there still exist several serious problems in headphone reproduction, such as, 'front-back confusion' and in-head localization'. These well-known problems are in general assessed by the subjective test that is based on human judgment. In this paper, an objective test is conducted in parallel with the subject test in order to validate the objective reproduction performance. Such a combined approach may be a more scientific and systematic approach to the reproduction performance.

• 대한원격탐사학회지
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• 제37권1호
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• pp.97-110
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• 2021

Fog can cause large-scale human and economic damages, including traffic systems and agriculture. So, Korea Meteorological Administration is operating about 290 visibility meters to improve the observation level of fog. However, it is still insufficient to detect very localized fog. In this study, high-resolution grid-type visibility data were retrieved from irregularly distributed visibility data across the country. To this end, three objective analysis techniques (Inverse Distance Weighting (IDW), Ordinary Kriging (OK) and Universal Kriging (UK)) were used. To find the best method and parameters, sensitivity test was performed for the effective radius, power parameter and variogram model that affect the level of objective analysis. Also, the effect of data distribution characteristics (level of normality) on the performance level of objective analysis was evaluated. IDW showed a relatively high level of objective analysis in terms of bias, RMSE and correlation, and the performance is inversely proportional to the effective radius and power parameter. However, the two Krigings showed relatively low level of objective analysis, in particular, greatly weakened the variability of the variables, although the level of output was different depending on the variogram model used. As the level of objective analysis is greatly influenced by the distribution characteristics of data, power, and models used, care should be taken when selecting objective analysis techniques and parameters.