• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.448-456
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• 2003

The prime objective of many facial wrinkle-reduction treatments is to achieve visible improvement. Thus the visibility of before/after treatment differences is often part of an efficacy assessment. This paper investigates whether the background knowledge of the people acting as observers in such assessments is of impact on the results: e.g. the subjects themselves are familiar with their faces, skin professionals have much experience in judging skin quality, and thus both might be more sensitive to small changes. In a clinical study 44 Female subjects were regularly treated during a period of 12 weeks with one of three wrinkle-reduction methods: K, Land M (placebo). Photographs were taken before treatment and at 6 and 12 weeks. The photographs were judged by 3 types of observers:ㆍ24 Lay observers were given the 0＆6-week and the 0＆12-week photo pairs of all subjects to indicate the one with the least wrinkles in a two-alternative forced-choice (TAFC) procedure.ㆍThe subjects themselves were given the 0＆6-weel and the 0＆12-week pair of their own photos (8 replications) to indicate the photo with the least wrinkles (TAFC).ㆍA trained panel of skin professionals (N=3) each gave 9-point Fitzpatrick wrinkle-severity scores for all individual 0-week and 12-week photos. We found that the lay observers perceived the same differences as the subjects themselves: significant improvements after 12 weeks for treatment K (p<0.0005 and p=0.005, respectively), no visible effects for treatments Land M, and, most importantly, a significant difference between treatments K and M/placebo (p=0.02 and p=0.04, respectively). Also the trained panel found this difference between K and M (p=0.013), but here it was due to a significant deterioration over time of the 'placebo-treated' wrinkles (M, p=0.03). Thus in conclusion we have found no indications that extra knowledge - in the form of familiarity with the own face or in the form of professional training - results in the identification of more treatments that show significantly visible wrinkle-reduction.

• Journal of Periodontal and Implant Science
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• v.40 no.4
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• pp.188-193
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• 2010

Purpose: The aim of this study is to assess the influence exerted by the observer's dental specialization and compare patients' opinion with observers' opinion of the esthetics of maxillary single-tooth implants in the esthetic zone. Methods: Forty-one adult patients, who were treated with a single implant in the esthetic zone, were enrolled in this study. Eight observers (2 periodontists, 2 prosthodontists, 2 orthodontists and 2 senior dental students) applied the pink esthetic score (PES)/white esthetic score (WES) to 41 implant-supported single restorations twice with an interval of 4 weeks. We used a visual analog scale (VAS) to assess the patient's satisfaction with the treatment outcome from an esthetic point of view. Results: In the PES/WES, very good and moderate intraobserver agreements were noted between the first and second rating. The mean total PES/WES was $11.19{\pm}3.59$. The mean PES was $5.17{\pm}2.29$ and mean WES was $6.02{\pm}1.96$. In the total PES/WES, the difference between the groups was not significant. However, in the WES, the difference between the groups was significant and prosthodontists were found to have assigned poorer ratings than the other groups. Periodontists gave higher ratings than prosthodontists and senior dental students. Orthodontists were clearly more critical than the other observers. The statistical analysis revealed statistically significant correlation between patients' esthetic perception and dentists' perception of the anterior tooth. However, the correlation between the total PES/WES and the VAS score for the first premolar was not statistically significant. Conclusions: The PES/WES is an objective tool in rating the esthetics of implant supported single crowns and adjacent soft tissues. Orthodontists were the most critical observers, while periodontists were more generous than other observers. The statistical analysis revealed a statistically significant correlation between patients' esthetic perception and dentists' perception of the anterior tooth.

• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.83-90
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• 2011

It has been very important to have an exact evaluation for risk factors in order to prevent WMSDs(Work-related Musculoskeletal Disorders). However, most WMSDs evaluation methods have always been some problems of possibilities associated with subjective evaluation. Therefore, this study tried to conduct a sort of usability analysis on three major evaluation methods(OWAS, RULA, REBA). Specifically, major subjects in the study consisted of three parts as follows; comparison of the results between experienced and inexperienced observers, analysis for the consistency of the results in terms of different evaluation times, and analysis for the consistency of the results in terms of different job characteristics(based on the part of the automobile). The results of the study were summarized as follows; 1) There was statistically significant difference of the results by RULA and by REBA between experienced and inexperienced observers. This might be due to the fact that experienced observers have had better ability to detect the important working posture during evaluation. However, the results by OWAS did not give any significantly different results between experienced and inexperienced observers, 2) All three checklists applied by experienced subjects did not show any single result significantly different in terms of different evaluation times. This might have to do with high intra-observer reliability from some of previous studies, 3) The five parts of an automobile were selected as five major jobs with different job characteristics in the automobile industry. Specifically, they were door part, front part(hood, etc.), inside part(dash board, seats, etc.), rear part(trunk etc.), and bottom part. All three methods did not show any significant differences for the results from each observers. Further study on this subject would eventually provide a sophisticated evaluating guidelines for WMSDs regarding determination of observer-specific evaluation, identification of repetitive number of evaluations for stable results for each checklist, determination of job-specific evaluation methods, and so on.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.2
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• pp.125-135
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• 2008

Backlash in the actuator is one of the most important nonlinearities that limit the performance of speed and position control of mechanical systems. In this paper, we propose disturbance observers in order to estimate the effect of nonlinearities and cancel them subsequently. As a result the disturbance observers make the nonlinear system behave linearly. And finally we show that the disturbance observers guarantee the system robustness and the performance to reject the effect of backlash in the face of parameter uncertainties.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.6
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• pp.573-580
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• 2009

In this paper, we develop a functional test model for magnetic bearing wheels. The functional test model is an electromagnetic levitation system that has three degree of freedom, which consists of one axial suspension from gravity and two axes gimbaling capability to small angels. A nonlinear controller with high-gain observers is proposed and the real-time experiment results show that the rotor is accurately levitated at the desired position and well-balanced, which is a suitable result for the potential use an magnetic bearing wheels. Also, the proposed scheme exhibits better performance when it is compared with the conventional PID control method.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.418-422
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• 2001

To achieve a high performance in direct vector control of induction motor, it is essential to correct estimation of rotor flux. The accuracy of flux observers for induction machines inherently depends on parameter sensitivity. This paper presents an analysis method for conventional flux observers using Parameter Sensitivity. The Parameter sensitivity is defined as the ratio of the percentage change in the system transfer function to the percentage change of the parameter variation. We define the ratio between real flux and estimated flux as the transfer function, and analyzed a parameter sensitivity of this transfer function by simulation.

• Current Optics and Photonics
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• v.2 no.1
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• pp.101-106
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• 2018

Color-normal observers (CNOs) and color-deficient observers (CDOs) have different preferences and emotions for color images. A color-image quality-enhancement algorithm for a CDO is developed to easily adjust images according to each observer's preference or image quality factors. The color-perception differences between CDO and CNO are analyzed and modeled in terms of the YCbCr chroma ratio and hue difference; then the color-shift method is designed to control the degree of color difference.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.250-255
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• 1993

In this paper, for detection and isolation of instrument and process faults related with steam generator(S/G) in nuclear power plant, two types of observers are designed based on the linearized dynamic model of S/G : a bank of Dedicated Observers (DOS) for instrument faults detection and a bank of Unknown Input Observers(UIO) for process faults detection. And then, they are combined to decide which one between the above two faults occurs. In principle, the failure in ith instrument(process) can be isolated by monitoring the error between the ith output and its estimation obtained from the ith DOS(UIO). It is shown via computer simulations that the present scheme is feasible in finding out the source of a fault.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1249-1254
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• 2006

Existing adaptive observers may cause the parameter drifts due to disturbances even if state estimation errors remain small. To avoid the drift phenomena in the presence of bounded disturbances, several robust adaptive observers have been introduced addressing bounds in state and parameter estimates. However, it is not easy for these observers to manipulate the size of the bounds with the selection of the observer gain. In order to reduce estimation errors, this paper introduces the (equation omitted) gain minimization problem in the adaptive observer structure, which minimizes the (equation omitted) gain between disturbances and estimation errors. The stability condition of the adaptive observer is reformulated as a linear matrix inequality, and the observer gain is optimally chosen by solving the convex optimization problem. The estimation performance is demonstrated through a numerical example.

• Journal of the Korean Home Economics Association
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• v.29 no.1
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• pp.37-49
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• 1991

The purpose of this study was to investigate the visual effects of clothing design. The specific objectives were: 1) to develop a clothing design evaluation instrument using semantic differential scales for the purpose of measuring visual responses with clothing design: 2) to identify the factor structure of the clothing design evaluation instrument: 3) to test the differences of perception to the clothing design depending on sex and knowledge about clothing design. The major findings were: 1. 37 pairs of descriptors of clothing form were found to include five factor dimensions (total variance:62.1%). Five major factors were found: attractiveness, practicability, elegance, comfort, hardness and softness. 2. for the visual evaluation of silhouettes, there were significant differences. H-line was explained by the simple image. A-line was explained by the comfortable image. V-line was explained by the mature and refined image. X-line was explained by the attractive and femine image and evaluated positively. 3. For the visual evaluation of observers, there were partly significant differences depending on sex and knowledge about clothing design in the observers' responses. But there were greater differences depending on sex than knowledge about clothing design in the observers' responses.