• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.372-377
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• 2007

For more than 2,500 years, surgical teaching has been based on the so called "see one, do one, teach one" paradigm, in which the surgical trainee learns by operating on patients under close supervision of peers and superiors. However, higher demands on the quality of patient care and rising malpractice costs have made it increasingly risky to train on patients. Minimally invasive surgery, in particular, has made it more difficult for an instructor to demonstrate the required manual skills. It has been recognized that, similar to flight simulators for pilots, virtual reality (VR) based surgical simulators promise a safer and more comprehensive way to train manual skills of medical personnel in general and surgeons in particular. One of the major challenges in the development of VR-based surgical trainers is the real-time and realistic simulation of interactions between surgical instruments and biological tissues. It involves multi-disciplinary research areas including soft tissue mechanical behavior, tool-tissue contact mechanics, computer haptics, computer graphics and robotics integrated into VR-based training systems. The research described in this paper addresses the problem of characterizing soft tissue properties for medical virtual environments. A system to measure in vivo mechanical properties of soft tissues was designed, and eleven sets of animal experiments were performed to measure in vivo and in vitro biomechanical properties of porcine intra-abdominal organs. Viscoelastic tissue parameters were then extracted by matching finite element model predictions with the empirical data. Finally, the tissue parameters were combined with geometric organ models segmented from the Visible Human Dataset and integrated into a minimally invasive surgical simulation system consisting of haptic interface devices and a graphic display.

• Journal of Communications and Networks
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• 제18권6호
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• pp.892-901
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• 2016

In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.

• 대한물리치료과학회지
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• 제30권4호
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• pp.92-110
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• 2023

Background: Digital therapeutics are software medical devices that provide evidence-based treatments to prevent, manage, and treat disease. Digital therapies have recently been shown to be effective in motivating children with cerebral palsy as a tool in neuropsychological therapy. Digital therapies improve postural control, balance and gait in children with cerebral palsy. Therefore, this study aims to investigate the effects of digital therapies on balance and gait in children with cerebral palsy and to provide guidelines for prescribing digital therapies for children with cerebral palsy. Design: A Systematic Review Methods: This study searched for English-language articles published in medical journals from January 2000 to July 2023 using PubMed and MEDLINE based on the year of initiation of the digital therapy. The search terms used in the study were 'digital technology' OR 'digital therapeutic' OR 'mobile application' OR 'mobile health' OR 'virtual reality' OR 'game' AND 'cerebral palsy', 'balance' 'gait' as the main keywords. The final article was assigned an evidence level and a Physiotherapy Evidence Database (PEDro) score to assess the quality of clinical trials studies. Results: The digital therapies applied to improve balance and gait in children with cerebral palsy are game-based virtual reality training and the Nintendo Wii Fit program. Both digital therapy interventions had a significant effect on improving balance in children with cerebral palsy, and virtual reality training significantly improved balance and gait. However, there were no significant improvements in balance and gait within two weeks of treatment, regardless of the type of digital intervention. Conclusion: The study suggests that this data will be important in building the evidence base for the effectiveness of digital therapies on balance and gait in children with cerebral palsy and in advancing clinical protocols.

• 컴퓨터교육학회논문지
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• 제4권1호
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• pp.77-85
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• 2001

가상교육은 사회 전역에서 새로운 교육 수단으로서 그 위치를 넓혀 가고 있다. 가상 연수원, 가상 대학 등 많은 가상교육 기관들이 새롭게 생겨나고 있으며, 인터넷 관련 기술의 발달에 따라 원활한 가상교육을 지원하는 새로운 시스템들도 등장하고 있다. 그러나 처음에는 아무런 문제없던 시스템도 학습자와 컨텐츠가 증가할수록 점차 속도가 느려지게 되고 많은 문제점들이 발생하게 된다. 하드웨어 장비 업그레이드를 통해 이러한 문제점을 해결할 수 있지만 이는 매우 많은 비용이 소요되며 불필요한 시스템 자원의 낭비가 아닐 수 없다. 따라서 본 논문에서는 가상교육 지원 시스템의 성능을 향상시킬 수 있는 방안을 모색해 보고자 다양한 상황 아래에서 시뮬레이션을 통해 서버의 성능을 테스트하고 그 개선 방안을 찾아보았다. 비록 단편적인 시뮬레이션이긴 하지만 이러한 개선 방안을 기초로 하여 서버 프로그램을 수정 보완한다면 충분한 성능 향상을 기대할 수 있을 것이며 원활한 가상교육을 위한 자료로서도 충분한 가치가 있을 것이다.

• 대한통합의학회지
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• 제7권1호
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• pp.1-8
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• 2019

Purpose : The purpose of this study was to examine the correlation between static and dynamic balance according to the virtual reality-based squat and conventional squat exercise. Methods : Twenty four participants were randomly assigned to the virtual reality-based squat (VRS) group (n=12) or conventional squat (CS) group (n=12). The static balance (C90 area, C90 angle, trace length, sway average velocity) and dynamic balance (forward, rearward, leftward, rightward) were measured using a force plate by BT4. The VRS group used the virtual reality system during 4 weeks, while the CS group underwent classical squat training. Independent t-test was used to test the homogeneity of the general characteristics of the subjects. The collected data was analyzed using the paired t-test for static and dynamic balance comparisons before and after exercise in both groups and Pearson's test for the correlation between static and dynamic balance according to the measured time. The significance level was set to 0.05. Results : There was no significant correlation between group and static and dynamic balance related variables (p>.05). There was a significant correlation between measurement time and static and dynamic balance related variables (p<.05). According to the measurement time, the static balance parameter C90 area in the VRS group after exercise was significantly decreased (p<.05). The values of forward, leftward and rightward in the VRS group were significantly increased after exercise (p<.05). Conclusion : It is suggested that 20 normal healthy adult men and women who have normal balance ability can improve their ability to control their posture by improving the balance ability when applying virtual reality-based squat exercise.

• 사물인터넷융복합논문지
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• 제8권2호
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• pp.49-54
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• 2022

실감형 콘텐츠는 사용자의 오감을 극대화하여 실제와 유사한 경험을 제공하는 콘텐츠로 가상현실, 증강현실, 혼합현실 등이 이에 속한다. 실감형 콘텐츠에서 사용자에게 실재감을 제공하기 위해서는 실제와 같은 시각적 이미지와 청각, 촉감 등을 제공해야 한다. 그러나 실감형 콘텐츠를 개발하기 위한 급격한 환경 변화로 인해 인력 양성 교육 전문가는 교육 과정 설계에 어려움을 겪고 있다. 본 연구에서는 실감형 콘텐츠 인재 양성 전문가에게 도움을 주기 위해 드론을 활용하여 실세계 측정 데이터를 취득·가공하고, 도출된 데이터를 VR/AR/MR에 적용하는 일련의 교육 과정을 제안한다. 설계 과정은 기업과 학생, 지역 사회에 대한 수요조사와 분석을 통해 교과과정을 구성한다. 본 연구는 실감형 콘텐츠 인력 양성을 시도하려는 교육 전문가에게 유익한 자료가 될 수 있다.

• 인터넷정보학회논문지
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• 제7권4호
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• pp.45-55
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• 2006

본 논문에서는 현장감 있는 모의훈련을 위해 가상영상이 아닌 지상기반 CCD 카메라영상에 지정된 시나리오대로 가상표적을 전시하는 방법을 제안한다. 이를 위해 고해상도 GeoTIFF(Geonraphic Tag Image File Format) 위성영상과 DTED(Digital Terrain Elevation Data)를 이용하여 현실감 있는 3차원 모델을 생성(운용자용)하고 입력된 CCD 영상(운용자 훈련자용)으로부터 도로를 추출하였다. 그러나 위성영상과 지상기반 센서영상은 관측위치, 분해능, 스케일 등에 많은 차이가 있어 특징기반 정합이 어렵다. 따라서 본 논문에서는 영상 워핑함수인 TPS(Thin-Plate Spline) 보간 함수를 일치하는 두 개의 제어점 집합에 적용하여 3차원 모델에 표시된 이동경로를 따라 CCD 영상에도 표적을 전시하는 이동 동기화 방법을 제안하였다. 실험에서는 대전지역의 위성영상과 CCD 영상을 이용하여 제안한 알고리즘의 유효성을 입증하였다.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 1999년도 추계학술대회
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• pp.381-389
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• 1999

One of the objectives of any task design is to provide a safe and helpful workplace for the employees. The safety and health module may include means for confronting the design with safety and health regulations and standards as well as tools for obstacles and collisions detection (such as error models and simulators). Virtual Reality is a leading edge technology which has only very recently become available on platforms and at prices accessible to the majority of simulation engineers. The design of an automated manufacturing system is a complicated, multidisciplinary task that requires involvement of several specialists. In this paper, a design procedure that facilitates the safety and ergonomic considerations of an automated manufacturing system are described. The procedure consists of the following major steps: Data collection and analysis of the data, creation of a three-dimensional simulation model of the work environment, simulation for safety analysis and risk assessment, development of safety solutions, selection of the preferred solutions, implementation of the selected solutions, reporting, and training When improving the safety of an existing system the three-dimensional simulation model helps the designer to perceive the work from operators point of view objectively and safely without the exposure to hazards of the actual system.

• 품질경영학회지
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• 제48권1호
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• pp.13-27
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• 2020

Purpose: The purpose of this study is to present a recoil measurement and analysis of K2 rifle for the development of a virtual reality marksmanship training in the Republic of Korea Army. Methods: For the recoil measurement, a test-bed is built by a barrel that has exact dimensions of K2 rifle and three piezoelectric pressure sensors mounted on the barrel. Data of over 200 rounds of 5.56mm M193 and K100 bullets are collected and analyzed from live fire experiments. For the recoil analysis, both the free recoil method and the gas exhaust aftereffect method are used to calculate a recoil velocity, momentum and kinetic energy of K2 rifle by applying the law of conservation of momentum. In addition, a new method is proposed that uses the third law of motion and the chamber pressure model for the recoil measurement Results: The results show how different between the previous and proposed methods with respect to M193 and K100 bullets of K2 rifle. In M193, the free recoil method demonstrates 1.113, 4.197, and 2.335, the gas exhaust aftereffect method computes 1.698, 6.407, and 5.441, and the proposed method calculates 0.990, 3.734, and 1.848 in recoil velocity, momentum and kinetic energy, respectively. In K100, the free recoil method demonstrates 1.190, 4.487, and 2.669, the gas exhaust aftereffect method computes 1.776, 6.699, and 5.949, and the proposed method calculates 1.060, 3.998, and 2.119 in recoil velocity, momentum and kinetic energy, respectively. Conclusion: This study implements live fire experiments to provide recoil velocity, momentum, and kinetic energy of K2 rifle using both M193 and K100 bullets. For the development of the army virtual reality marksmanship, the results in this paper would be useful to design and produce a gun and/or a rifle of virtual reality.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제10권1호
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• pp.19-28
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• 2021

최근 교육 분야에서는 가상현실 기술을 교육현장에 접목하여 교육 매체로 사용을 하고자 하는 시도들이 다양하게 진행되고 있다. 이에 과학교과 방면에서도 가상현실 환경 구축 기술을 이용하여 공간 및 상황 등의 여러 제한에서 벗어나 보다 다양하고 활동적인 실험을 할 수 있는 과학 실험 시뮬레이션을 필요로 하고 있다. 본 연구에서는 과학교과 중 물리 과목을 선택하여 물리 현상 중 하나인 포물선 운동 공식을 활용한 실험 시뮬레이션을 가상현실 공간에 구현한 뒤, 융합인재교육(STEAM) 이론의 학습 준거를 기준으로 실제 물리 교육에 활용이 가능함을 증명하였다. 이를 통해 가상현실 공간을 활용한 구체적인 교육 모형을 설계할 수 있음을 확인하였고, 전통적인 교육 모형과 현대적 기술의 접목으로 여러 교과에서 보다 효과적인 학습 방법으로 교육을 진행할 수 있음을 보여준다. 연구 결과와 관련하여 향후 연구 방안 및 실제 교육현장에서의 활용 가능성을 시사한다.