• Journal of Applied Reliability
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• v.17 no.2
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• pp.112-121
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• 2017

Purpose: The most previous works on designing accelerated life tests (ALTs) are focused on the application of a single stress. Because of the difficulty to obtain the sufficient information in a reasonable duration using single stress only, there is needed in practice to use multiple-stress ALTs frequently. This paper presents new practical plans with two stresses for Weibull distribution. Methods: The four-level practical plans based on rectangle test region are proposed and compared with the corresponding three-level statistically optimal plans. Sensitivity analyses for assumed design parameters and life-stress relationship are conducted. Results: A procedure to choose practical ALT plans is illustrated with a numerical example and guidelines for planning two-stress ALTs are provided. Conclusion: The proposed two-stress ALT plans on practical constraints to assess a quantile of Weibull lifetime distribution at the use condition are efficient and robust.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.7
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• pp.78-88
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• 1997

A three dimensional-two spatical dimensions plus time-image segmentation is widely used in a very low bit rate image sequence coding because it can solve the region correspondence problem. Mathematical morphology is a very efficient tool for the segmentation because it deals well with geometric features such as size, shape, contrast and connectivity. But if the motion in the image sequence is large in time axis, the conventional 3D morphological segmentation algorithm have difficulty in solving region correspondence problem. To alleviate this problem, we propose the hierarchical image sequence segmentation algorithm that uses the region motion information. Since the motion of a region in previous level affects that in current level uses the previous motion information to increase region correspondence. Simulation result shows improved performance for sequence frames with large motion.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.303-303
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• 2000

It is difficult to determine the static axle weight of a vehicle with weigh-in-motion systems which in absence measure instantaneous axle impact forces. The difficulty in determining a static axle weight results from dynamic effects induced by vehicle/road interactions. One method to improve the problem is to quantify a statistical confidence level for measured axle weight. The quarter-car model is used to simulate vehicle motion, Also, the road input to vehicle model can be characterized in statistical terms by PSD (power spectral density) of appropriate amplitude and frequency contents other than an exact spatial distribution. The confidence levels for the measured axle weight can be obtained by the random process analysis using both vehicle model and road input.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.165-172
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• 2010

In Web-based learning systems, the techniques, as self-regulated learning, self-directed learning, are used to improve the effect of learner's study. These techniques are methods considering learner's study level but to consider the learner's study ability properly, the tailored course for learner should be applied. In this research, the learning system considering learner's study ability was proposed. To decide a learner's study ability, IRT(Item Response Theory) was applied and learning contents and question items were developed and applied by the degree of difficulty.

• Journal of Korea Game Society
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• v.6 no.1
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• pp.3-10
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• 2006

In computer games, the level design and balance of characters are the key features for developing interesting games. Level designers make decision to change the parameters and opponent behaviors in order to avoid the player getting extremely frustrated with the improper level. Generally, opponent behavior is defined by static script, this causes the games to have static difficulty level and static environment. Therefore, it is difficult to keep track of the user playing interest, because a player can easily adapt to changeless repetition. In this paper, we propose a dynamic scripting method that able to maintain the level designers' intention where user enjoys the game by adjusting the opponent behavior while playing the game. The player's countermeasure pattern for dynamic level design is modeled using a Gaussian Mixture Model (GMM). The proposed method is applied to a shooting game, and the experimental results maintain the degree of interest intended by the level designer.

• 재활복지
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• v.21 no.2
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• pp.169-190
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• 2017

The purpose of this study was to investigate item goodness-of-fit of Scale, Rasch rating scale model was applied to 5 dimensions 24 items of the Test of Performance Strategies (TOPS) in a sample of athletes with physical disabilities (n=215). An assumption to test Rasch Model, which is satisfaction of unidimensionality, is regarded through PCAR test, and WINSTEPS 3.65 program is used to test the goodness-of-fit of items. The results of this study were: First, 3-point rating category was appropriate for the TOPS instead of the existing 5-point rating category. Second, as a result of analyzing the goodness-of-fit of the items, 21 items of the TOPS were suitable, but 3 items were not. Third, the item reliability of person separation of the TOPS was acceptable, but the person reliability of item separation was not suitable and it was necessary to adjust the item order considering the difficulty level of the items. Fourth, as a result of comparing the individual attribute score and the difficulty level through the Item-Person Map, the distribution of the item difficulty distribution was shown to be biased in some factors compared to the personal attribute score distribution.

• 재활복지
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• v.18 no.4
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• pp.315-330
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• 2014

The purpose of this study was to verify the construct validity of the Sensory Profile for children with congenital cerebral palsy. Parents of 87 children(the ages of 3 to 10) with congenital cerebral palsy participated in this study. The data were analyzed through Winstep version 3.81 using the Rasch model to examine the uni-dimensionality of the fit of each item, the distribution of difficulty of each item, and the reliability and appropriateness of the rating scale. Based on a Rasch analysis, four out of the 87 children were considered to be inappropriate participants, and 15 item of the Sensory Profile was determined to be an inappropriate item. The items of high-level difficulty are needed as new items of the Korean Sensory Profile. The rating scale of three categories were appropriate than those of the five categories. The person and item separation reliability of three categories was above 0.90, which is a relatively excellent value. Finally, it will be need to verify of validity for Korean version of Sensory Profile, to develop new item of a high level of difficulty and convert into three point rating scale.

• Therapeutic Science for Rehabilitation
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• v.11 no.3
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• pp.65-80
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• 2022

Objective : This study examined the psychometric properties of the 12-item Coping Orientation to Problems Experienced Scale (COPE) using Rasch analysis. COPE is one of the instruments used to measure stress-coping skills. Methods : The study participants were 480 community-dwelling older adults. We tested the instrument's unidimensionality assumption using principal component analysis (PCA). Item fit was examined using infit-and-outfit mean-square (MnSq) and standardized fit statistics (ZSTD). The precision and item difficulty hierarchies of the instrument were examined. The item-difficulty hierarchy was investigated to identify the easy and difficult items. We tested differential item functioning (DIF) for sex and age groups. Results : PCA revealed that the instrument met the unidimensionality assumption (eigenvalue = 1.78). Among the 12 items, item 2 was removed because of misfit (Infit MnSq = 1.33, Infit ZSTD = 5.05, Outfit MnSq = 1.56, Outfit ZSTD = 7.15). The remaining 11 items demonstrated a conceptual item-difficulty hierarchy. The person strata value was 3.10, which is equivalent to a reliability index value of 0.81. There was no DIF for the sex and age groups (DIF contrast <0.27). Conclusion : The findings indicated that the revised COPE-11 has adequate item-level psychometric properties and can accurately measure stress coping skills.

• Science of Emotion and Sensibility
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• v.12 no.3
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• pp.279-288
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• 2009

The purpose of this study was to verify the impact of cognitive factors and GSR on the task performance. For this study 64 students participated. Multiple regression and repeated measures were applied to analyze the data. The result for the survey indicated that previous knowledge, physical efforts, and task difficulty had significant impacts on task performance. Particularly, task difficulty has a negative impact. This can be interpreted as someone who has high prior knowledge inputs higher physical efforts with low task difficulty perception will show high performance. On the other hand, the low arousal level of GSR in the evaluation stage is a prediction variable of task performance. This result shows that high prior knowledge and low arousal level of GSR produces high performance. However, the analysis of difference in GSR between learning and evaluation stages does not show significant difference. It suggests that physiological measure such as GSR is reliable index of cognitive load; however, it partially represents cognitive load. Other crucial factors should be added for comprehensive measures.

• Korea Journal of Hospital Management
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• v.7 no.1
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• pp.64-87
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• 2002

The purpose of this study is aimed to grasp the factors, which may influence the harmonized organizational efficiency of the objects of hospital structure as well as its structural constituents of each departments of administration, nursing, and para-medical personnels, in order to provide basic data enable to contribute in the development of hospital. The survey data involved in the study was derived from 385 personnels working in 5 medium and small sized hospitals in Seoul area. The main finding of the study can be summarized as follows; 1. The organizational efficiency in accordance with the general characteristics of subjects in order of male, over 30 years of age, university graduates, long-term tenure and high position is higher, whereas, in as much as wage and well trained personnels in administration departments are higher, its organizational efficiency is higher in comparison with those of nursing and para-medical departments. 2. The organizational efficiency in accordance with satisfaction and the motive contributional factors is higher as much as the high satisfactory level in every departments in general. 3. The organizational efficiency in accordance with the factors of job characteristics is higher in as much as difficulty of the jobs is lesser, however there was not statically significance between administration and para-medical departments. In as much as the job circulation is intact, job standard level is higher and the more job responsibility the higher organizational efficiency, while the more workload and the more work feud resulted lower organizational efficiency. It was obvious that the higher professional expertise as well as the training and application level are improving the organizational efficiency. 4. The organizational efficiency in accordance with the factors of structural characteristics was higher in as much as the intercommunication was smooth and the structural formalization level are higher, however there was not statically significance between the participation level of decision making and the organizational efficiency. 5. In as much as higher educational level of over university graduates, management of organization and the job level are satisfied, the psychological motive contributional level is higher, while the lesser job difficulty, the smooth job performance, the higher level of professional expertise, the higher structural formalization level, the smooth intercommunication, have affected as major influence factors of the structural characteristics of organizational efficiency. 6. As the management of hospital organization, the job level and personal relation are satisfied or psychological motive is provided, especially when there are no difficult jobs or smooth job circulation and no job feud are prevailing, it was apparent that the organizational efficiency is improving accordingly. The nursing departments has high educational standard and is satisfied in the management and job level of hospital organization as there are no difficult jobs while the level of hospital's organizational formality is high and the intercommunication is smooth, which are improving the organizational efficiency. The para-medical departments is also satisfied the management and job level of hospital organization and it was apparent that the organizational efficiency is higher in as much as the level of job standardization is high and the intercommunication is smooth. As a result of this study, in order for improving the organizational efficiency of the medium and small sized hospitals, the management and job level as well as personal relation are preferably satisfied, whereas the level of job circulation, job responsibility, the expertise and formalization of organization, intercommunication and etc. should be satisfied, and, therefore, it is advisable to buildup discriminated organizational management and environment for different division on the basis above factors. Since this study is carried on several hospitals in Seoul area, there is a certain limit to generalize its result to all domestic hospitals, nevertheless the gallop poll was made by developing the questionnaires with reasonability and reliability. Especially, as the study was carried by analyzing the comparison of influence factors' difference of organizational efficiency in accordance with the divisional characteristics of the medium and small sized hospitals.