• 산업공학
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• 제15권3호
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• pp.286-296
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• 2002

Products which are sold with warranty, preventive maintenance actions by manufacturers and/or buyers have an impact on the total costs for both parties. In this paper, we develop the models to study the expected warranty cost for products with free repairable warranty with three types of discrete preventive maintenance. We deal with by utilizing the concept that preventive maintenance reduces the virtual age of the system. We assume that the maintenance planning horizon can be segmented into k discrete and equally sized periods. In such a scenario, numerical examples are presented.

• Architectural research
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• 제15권4호
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• pp.175-182
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• 2013

This study aims to explore age-related differences with the assessment tools in the web-based 3D virtual model house and to propose the 3D model house criteria which everyone can use easily. The participants came from three age groups, ranging from their 20s to their over 40. Presence, Usability and Space perception and cognition in the experiment for navigating and evaluating the web-based 3D model house were measured and compared through one-way ANOVA and two-way ANOVA. The results and conclusions are as follows. (1) The younger the participants were, the more positive they evaluated the experiment on Presence. However, 20s needed higher presence than other two groups. (2) 30s and over 40 groups evaluated that the 3D virtual model house was more efficient than an actual model house on Usability. When the participants were younger, the values of 'expressivity' factor were higher. (3) The younger the participants were, the more positive they perceived the virtual environment (VE) on Space perception and cognition scale. There were no significant differences in the selection of dwelling size and the floor plan type. There were no significant differences of interaction effects between age and online gaming experience on Presence and Usability. The results of the current study demonstrate that there are differences among age groups and older groups have difficulty navigating and assessing in a VE. Although older groups take longer to adapt in the VE, they regard the 3D model house as an effective tool for purchase of house.

• 한국의류산업학회지
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• 제17권2호
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• pp.265-277
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• 2015

The aim of this study was to successfully reflect human body changes on the transformation of the virtual body within 3D virtual fitting spaces. For this purpose, existing problems of shape transformation of the virtual body were analyzed and regression equations which provides useful basic data for transformation of the virtual body that can be applied usefully to the 3D virtual fitting system was developed. Necessary data for the analyses were body measurement and 3D scan data of women with average physical form between the ages of 40 through 49. The reason that we used human body changes of the female subjects in their forties was based on the recognition that fundamental female body changes start to occur from age of forty. Body shapes were largely divided into 3 groups according to obesity which was found to be the biggest factor of shape change. Seven factors were extracted based on factor analysis of 47 body measurement categories and regression equations were created to extract specific measurements for each BMI group based on these seven factors. The major contribution of this paper can be summarized as follows. First, the regression equations to extract specific measurements based on the 7 representative variables remediated existing problem of virtual bodies as it increased the number of body shape transformation areas. Second, the regression equations helped to overcome the problem of current failing to reflecting changes in body cross-section shape based on simple girth measurements based on analysis of cross-section distances.

• 한국의류산업학회지
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• 제14권1호
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• pp.1-12
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• 2012

This research was analyzed regarding comparing features of expressions between clothes in movie, , and cyber clothes that were made by Marvelous Designer2 which is a design CAD. This research was studied to experiment an expressing possibility of clothes simulation software which was developed currently. Therefore, we picked clothes that are good at movement and detail in the movie. The dress theory of the renaissance which is the period background of movie, was considered and studied as pattern, silhouette, material, color, detail and animation. The movie's dresses are made with 3D virtual and compared so 3D virtual clothes's benefits and weaknesses can be analyzed. As a result, we found that 3D virtual dress can show the real movie's feature accordingly with current developed IT standard. This will assist a development in fashion industry and become a new indicator for 3D movie clothing.

• 대한통합의학회지
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• 제9권1호
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• pp.13-22
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• 2021

Purpose : The purpose of this study was to investigate the effects of a virtual reality-based occupational therapy program on the physical function and learning ability of intellectually disabled school-aged children. Methods : In this study, 20 intellectually disabled children of school age were randomly and evenly divided into experimental and control groups with children in the experimental group receiving a virtual reality-based occupational therapy intervention. The study adopted a pretest-posttest design. The intervention was conducted for a total of 12 sessions for six weeks, twice a week, and 50 minutes per session. As measurement tools, BOT-2 and grooved pegboard tests were used to compare physical function before and after the intervention program, and K-ABC was used to check changes in learning ability. Results : The occupational therapy program produced a significant improvement in both physical function and learning ability of the experimental group. A significant difference was observed between the experimental and control groups. Conclusion : This study confirmed the value and usefulness of virtual reality-based occupational therapy as a tool for enhancing the physical function and learning ability of intellectually disabled school-aged children. Based on the results, a variety of future studies are encouraged that would further test the effects of the occupational therapy program used here.

• 한국실내디자인학회논문집
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• 제15권6호
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• pp.101-110
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• 2006

Many architects in the second machine age experiment on the movement in architectural design. They consider a movement as a flow of information and vector as well as the real motion. They express the movement in architectural design as nomad architecture, network city, rhizome, mutual transformation among building, environment and visitors, and form generation as the actualization of the virtual. It is partly the result of the philosophy of Deleuze and Bergson that a movement is just a duration as a difference of quality. It is because Deleuze explains that the realization of the virtual as a becoming is also the kind of movement. This study analyzes the method of expression of movement in architectural design in the second machine age. As a result, the movement in architectural design in the second machine age was expressed in two ways. One method is a territorialized movement that moves in the fixed trajectory and the other is a deterritorialized movement that moves in the random indeterminate trajectory.

• Journal of Periodontal and Implant Science
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• 제48권2호
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• pp.124-134
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• 2018

Purpose: Clinicians must examine tooth wear to make a proper diagnosis. However, qualitative methosds of measuring tooth wear have many disadvantages. Therefore, this study aimed to develop and evaluate quantitative parameters using the cusp area and volume of virtual dental models. Methods: The subjects of this study were the same virtual models that were used in our former study. The same age group classification and new tooth wear index (NTWI) scoring system were also reused. A virtual occlusal plane was generated with the highest cusp points and lowered vertically from 0.2 to 0.8 mm to create offset planes. The area and volume of each cusp was then measured and added together. In addition to the former analysis, the differential features of each cusp were analyzed. Results: The scores of the new parameters differentiated the age and NTWI groups better than those analyzed in the former study. The Spearman ${\rho}$ coefficients between the total area and the area of each cusp also showed higher scores at the levels of 0.6 mm (0.6A) and 0.8A. The mesiolingual cusp (MLC) showed a statistically significant difference (P<0.01) from the other cusps in the paired t-test. Additionally, the MLC exhibited the highest percentage of change at 0.6A in some age and NTWI groups. Regarding the age groups, the MLC showed the highest score in groups 1 and 2. For the NTWI groups, the MLC was not significantly different in groups 3 and 4. These results support the proposal that the lingual cusp exhibits rapid wear because it serves as a functional cusp. Conclusions: Although this study has limitations due to its cross-sectional nature, it suggests better quantitative parameters and analytical tools for the characteristics of cusp wear.

• 전자통신동향분석
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• 제34권2호
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• pp.19-28
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• 2019

In recent years, medical and health care fields have attracted attention for virtual reality (VR) applications. VR technology is emerging as a healthcare specialist and psychotherapy alternative to cope with the increase in the demand for the treatment of conditions such as psychological diseases caused by old age and stress. Using VR, virtual patients or organs can be trained, and the medical staff can plan and pre-test before surgeries. The use of VR technology for psychotherapy and rehabilitation of one-to-one, face-to-face treatment allows a single physician to respond to multiple health care needs.

• 대한통합의학회지
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• 제10권3호
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• pp.233-246
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• 2022

Purpose : The study aims to determine the effects of virtual and non-virtual realities in a normal person's mirror walk on gait characteristics. Methods : Twenty male adults (Age: 27.8 ± 5.8 years) participated in the study. Reflection markers were attached to the subjects for motion analysis, and they walked in virtual reality environments with mirrors by wearing goggles that showed them the virtual environments. After walking in virtual environments, the subjects walked in non-virtual environments with mirrors a certain distance away after taking a 5 min break. To prevent the order effect caused by the experiential difference of gait order, the subjects were randomly classified into groups of 10 and the order was differentiated. During each walk, an infrared camera was used to detect motion and the marker positions were saved in real time. Results : Comparison between the virtual and non-virtual reality mirror walks showed that the movable range of the leg joints (ankle, knee, and hip joints), body joints (sacroiliac and atlantoaxial joints), and arm joints (shoulder and wrist joints) significantly differed. Temporal characteristics showed that compared to non-virtual gaits, the virtual gaits were slower and the cycle time and double limb support time of virtual gaits were longer. Furthermore, spacial characteristics showed that compared to non-virtual gaits, virtual gaits had shorter steps and stride lengths and longer stride width and horizontally longer center of movement. Conclusion : The reduction in the joint movement in virtual reality compared to that in non-virtual reality is due to adverse effects on balance and efficiency during walking. Moreover, the spatiotemporal characteristics change based on the gait mechanisms for balance, exhibiting that virtual walks are more demanding than non-virtual walks. However, note that the subject group is a normal group with no abnormalities in gait and balance and it is unclear whether the decrease in performance is due to the environment or fear. Therefore, the effects of the subject group's improvement and fear on the results need to be analyzed in future studies.

• PNF and Movement
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• 제16권2호
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• pp.207-216
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• 2018

Purpose: This study aimed to investigate the fully immersive virtual reality (FIVR) program changes in the autonomic nervous system (ANS) by age according to heart rate variability (HRV). Methods: A total of 44 subjects were classified into group 1(aged 20-30), group 2(aged 40-60), and group 3(aged 70 and above). The study analyzed the HRV using a pulse wave analyzer and compared the ANS changes before and after applying the FIVR of the group. The LF, HF, RMSSD, and SDNN were measured. Fifteen minutes of virtual reality applications were applied to all subjects, and 1 min of rest was given in the middle of the session. A was used for anteroposterior comparisons of the ANS. Results: The HF, LF, RMSSD, and SDNN values were not statistically significant in all groups, but they all increased. The RMSSD value was statistically significant because it increased in group 3 (p<0.05). Those of the other two groups were not statistically significant (p<0.05). Conclusion: An FIVR program does not have a negative effect on the ANS response.