• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.171-176
• /
• 2008

As one way of design optimization of two-stage two-cylinder rotary compressor used for R410A heat pump application, displacement volume ratio, being defined by the ratio of the second stage cylinder volume to that of the first stage, has been varied and its effect on the compressor performance has been investigated by a computer simulation program. For simplicity, only the cylinder height of the second stage was varied to change the volume ratio. With increasing the volume ratio in the range of VR=$0.55{\sim}0.9$, volumetric efficiency increased monotonically, but adiabatic efficiency showed a maximum at around VR=0.6. Mechanical efficiency was little influenced by the volumetric ratio. As a consequence, maximum improvement of the compressor performance was found at around VR=0.7. Compared to a one-stage two-cylinder rotary compressor with about the same cooling capacity, COP improvement was about 6.96%.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2010.04a
• /
• pp.141-144
• /
• 2010

건설공사 프로젝트는 기획, 설계, 시공, 운영 및 유지관리 등 각 단계의 다양한 참여 주제에 의해 프로젝트가 진행되고 각 분야 간 원활한 의사소통을 통한 협업으로 일을 진행해 나간다. 그러나 각 단계별 커뮤니케이션이 원활히 이뤄지기가 힘들며, 이러한 단계별 분절의 가장 큰 이유 중 하나가 실제적 결과물은 3차원 기반인 것에 비해, 그 과정이 2차원 CAD 시스템에 의존하는 결과와 과정의 격차 때문이다. 그로 인해 각 관련 분야에서 발생되는 정보의 불확실성, 부정확성, 표현의 애매모함 등으로 인해 재작업 및 불필요한 작업이 빈번히 발생하여 전체적인 공정의 지연 및 비용의 문제, 결과물의 품질에 대한 문제가 발생하고 있다. 또한 도면에서의 한계점인 거리감, 공간감 등 실제 사람이 느끼는 Scale감을 알 수 없어 공간에 대한 이해도가 떨어지는 한계점을 극복하지 못하고 있으며 1인칭 작업운영 방식으로 인하여 협업 설계과정에서 원활한 팀워크를 유도 할 수 없다. 따라서 본 연구에서는 협업설계 과정에서 기본설계 단계를 지원하는 설계 도구로서 건축모델의 단순 시각화에서 벗어나 가상공간에서 몰입형 VR 시뮬레이션을 구현하기 위하여 프로토타입 응용을 개발 하였고, 이것을 "Digital Studio"에 구현하여 즉각적인 공간 시뮬레이션을 통하여 실제 시공 전에 문제점들을 검토 및 보완하고 전체적으로는 생산성 향상과 설계 과정 중 오류를 최소화하기 위한 VR시뮬레이션 시스템의 제안 및 Viewer 모듈을 개발 하였다.

• Physical Therapy Rehabilitation Science
• /
• v.2 no.1
• /
• pp.7-11
• /
• 2013

Objective: Final goal of nerve advancement therapy is to provide maximum ability to function independently in life to patients. This paper appraises and describes basic concepts of the virtual reality (VR) based exercise program to improve functional movement for neurologically impaired patients. Design: Review article. Methods: Stroke patients from the physical therapy department while wearing comfortable clothing receive therapy and also VR based motion therapy administered by the therapist in charge. After evaluation of stroke patients, therapy includes an exercise program that is suitable for use with stroke patients; stroke patients wear head-mounted display while in front of the computer, where the camera is located; they follow the action on the screen and the computer perceives the operation of the stroke patients according to subject accomplishment. Results: According to obstacle condition of stroke patients using the method, which is various environments after setting, in stroke patients, there is a possibility of presenting suitable therapeutic environments. The display presentation of the method, which is identical, causes difficulty for all stroke patients. According to subject accomplishment; stroke patients result in execution of repetition training and deepening study, which leads to mobility. Conclusions: The VR based rehabilitation training programs is a difference of the existing video training program, is immediate feedback and compensation method. It will provide rehabilitation training services for the family of the patient whose condition could be improved with rehabilitative therapy where it is a continuous circumstance as a matter of the social welfare facility therapy.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.1
• /
• pp.291-304
• /
• 2019

This paper proposes a dynamic-tiling-based bandwidth-efficient (DTBE) virtual reality (VR) streaming scheme. We consider 360-degree VR contents with multiple view points such as the front, back, upper, and bottom sides. At a given time, the focus of a client is always bound to a certain view among multiple view points. By utilizing this perspective, under our proposed scheme, tiles with high encoding rates are selectively assigned to the focused view where multiple view points consist of multiple tiles with different encoding rates. The other tiles with low encoding rates are assigned to the remaining view points. Furthermore, for reducing view adaptation delay, we design a novel rapid view adaptation mechanism that selectively delivers an I-frame during view point updates by using frame indexing. We implement the proposed scheme on a commercial VR test bed where we adopt the MPEG media transport (MMT) standard with high-efficiency video coding (HEVC) tile modes. The measurement-based experiments show that the proposed scheme achieves an average data usage reduction of almost 65.2% as well as average view adaptation delay reduction of almost 57.7%.

• International Journal of Internet, Broadcasting and Communication
• /
• v.13 no.1
• /
• pp.116-122
• /
• 2021

This study evaluated the effect of simulation training on cardiac arrest in hospitals for inactive nurses with 360 VR content, and attempted to prepare basic data for simulation training for inactiv nurses in the future. The design of this study is an experiment study before and after a single group. The study period was from October 13, 2020 to December 17, 2020. The subjects of the study were a total of 21 nurses who participated in the education program for inactive nurses. For simulation training for inactive nurses, Microsoft Powerpoint, hybrid simulation, high-fidelity simulation, and 360 VR content were applied for theories education and practical education. As a result of the study, the satisfaction level of the curriculum for the cardiac arrest situation in the hospital for inactive nurses was 4.78±0.36 points out of 5 points. Understanding of education was 4.71±0.46 points out of 5 points. Usefulness of education was 4.80±0.40 points out of 5 points. Confidence in airway maintenance before and after training, BLS review, manual defibrillator, emergency medication administration, airway maintenance, emergency situation simulation, and debriefing were all significant. According to the results of this study, simulation training of the situation of cardiac arrest in the hospitals for inactive nurses was effective. In future studies, it will be necessary to develope and verify specific teaching and learning methods by applying various cases of cardiac arrest situations in consideration of the type of hospitals.

• Journal of Distribution Science
• /
• v.19 no.9
• /
• pp.41-52
• /
• 2021

Purpose: Virtual reality is a unique technology to distribute data and demonstrates user's understanding towards complex products. The objective of this research is to investigate the impact of virtual reality on real world purchase intention of automotive cutting tools in Thailand's exhibitions. Hence, the research framework was constructed by telepresence, perception narrative, authenticity, trustworthiness, functional value, aesthetics, and purchase intention. Research design, data and methodology: Samples were collected from 500 visitors who participated in the selected top two metalworking exhibitions. Mix sampling approach is applied by using non-probability sampling methods of purposive or judgmental sampling, quota sampling, and convenience sampling method, respectively to reach target samples. Confirmatory Factor Analysis (CFA) and Structural Equation Model (SEM) were used to analyze and confirm goodness-of-fit of the model and hypothesis testing. Results: The results indicate that authenticity, functional value, and trustworthiness induced higher experiential value towards purchase intention. Those variables are stimulated by telepresence and perception narrative towards VR experience. Conclusions: Consumer's purchase intention towards VR experience on engineering cutting tools rely on consumer's sense of authenticity, trustworthiness, and functional value. Hence, marketing practitioners in automotive companies are encouraged to develop VR which focusing on significant factors to enhance consumers purchase intention.

• International Journal of Advanced Culture Technology
• /
• v.11 no.1
• /
• pp.270-275
• /
• 2023

The government has defined domestic violence as one of the four major social evils and tried to prepare laws and systems to prevent it. Nevertheless, domestic violence has emerged as a serious social issue, and compare to the number of domestic violence cases that are constantly increasing, the report rate of domestic violence is significantly lower. This suggests the need to improve citizens' perception of domestic violence as the issue to solve it together in society, not as a private matter at home. Most of existing contents for preventing domestic violence and improving awareness are simple viewing forms of video contents, which have little effect on recognition. We aim to confirm the possibility of improving social awareness about domestic violence by producing Virtual Reality (VR) contents that have great features of user's immersion and empathy. In this VR content, the user can interact with various objects in the virtual reality of domestic violence and directly or indirectly experience the victim's position. Users who view the violent environment from the victim's point of view can have a subjective empathy for the problem, which is expected to induce more active awareness about domestic violence.

• Journal of information and communication convergence engineering
• /
• v.21 no.4
• /
• pp.300-305
• /
• 2023

Audience reactions in response to remote virtual performances must be compressed before being transmitted to the server. The server, which aggregates these data for group insights, requires a distribution code for the transfer. Recently, distributed learning algorithms such as federated learning have gained attention as alternatives that satisfy both the information security and efficiency requirements. In distributed learning, no individual user has access to complete information, and the objective is to achieve a learning effect similar to that achieved with the entire information. It is therefore important to distribute interdependent information among users and subsequently aggregate this information following training. In this paper, we present a new extension technique for minimal code that allows a new minimal code with a different length and Hamming weight to be generated through the product of any vector and a given minimal code. Thus, the proposed technique can generate minimal codes with previously unknown parameters. We also present a scenario wherein these combined methods can be applied.

• Journal of East-West Nursing Research
• /
• v.29 no.2
• /
• pp.141-149
• /
• 2023

Purpose: The purpose of this study was to verify the effects of virtual reality (VR) based anatomy education program on nursing students' learning presence, technology acceptance, learning motivation, and knowledge. Methods: A nonequivalent control group pre-test and post-test design was employed. The study participants included 113 nursing students (56 in the experimental group and 57 in the control group) from Ansan City. Data collection was conducted from June 1 through 23. Data were analyzed using χ²-test, Fisher's exact test, and t-test using SPSS 23.0 program. Results: The experimental group had a significant increase in learning presence, technology acceptance, and knowledge before and after the intervention compared to the control group. Conclusion: Virtual reality based anatomy education is an effective learner-centered educational program. From an educational perspective, VR anatomy education programs can improve anatomy knowledge by increasing students' acceptance of VR technology and increase their motivation to learn by increasing their sense of presence.

• Journal of Distribution Science
• /
• v.22 no.6
• /
• pp.33-44
• /
• 2024

Purpose: This study aims to measure how information quality, system quality, security, usefulness, and ease of use of Augmented Reality (VR) and Virtual Reality (AR) influence user satisfaction, motivating intelligent travel technology developers to improve VR/AR quality to meet customer requirements. Research design, data and methodology: This study investigates users interested in travelling in Ho Chi Minh City and Nha Trang City, Vietnam. The research model was implemented using an online questionnaire and face-to-face from 405 valid samples. To evaluate the scale's reliability, the study used the software SPSS 20. Test research hypotheses and evaluate measurement and structural models. This research uses AMOS 20 software. The proposed model is firmly grounded in the Information System Success model (ISS) and the Technology Acceptance Model (TAM), providing a solid theoretical foundation for our research. Results: Results show that consumer perceptions of information quality, system quality, security, usefulness, and ease of use have a positive impact on the perceived quality of VR/AR, thereby influencing tourists' travel intention. Conclusions: The results of this research enrich the theoretical understanding of consumer behaviour toward intelligent technology products in tourism, providing management implications for manufacturers to improve the quality of tourism products and satisfy user requirements in experience before considering choosing a destination.