• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.11
• /
• pp.1500-1506
• /
• 2020

In this paper, we study a scheduling problem based on reinforcement learning for overlay device-to-device (D2D) communication networks. Even though various technologies for D2D communication networks using Q-learning, which is one of reinforcement learning models, have been studied, Q-learning causes a tremendous complexity as the number of states and actions increases. In order to solve this problem, D2D communication technologies based on Deep Q Network (DQN) have been studied. In this paper, we thus design a DQN model by considering the characteristics of wireless communication systems, and propose a distributed scheduling scheme based on the DQN model that can reduce feedback and signaling overhead. The proposed model trains all parameters in a centralized manner, and transfers the final trained parameters to all mobiles. All mobiles individually determine their actions by using the transferred parameters. We analyze the performance of the proposed scheme by computer simulation and compare it with optimal scheme, opportunistic selection scheme and full transmission scheme.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.1
• /
• pp.1-8
• /
• 2014

This paper proposed a method that prevents data leakage and modulation and detects an unauthorized device by using AP and mobile device. Most of existing method for detecting and preventing an unauthorized device are similar to type of Evil Twin. However, in previous studies can not resolve many security accident and have the problem to cope with effectively security accident on various network. In order to solve these problem, companies prepare security accident through the varies policy and guideline. but It is hard to prevent all security accident because it is consistently increasing everyday. This paper suggests technique of detecting and preventing an unauthorized device using Context Awareness and Mobile Device Management. Firstly, when mobile device go into internal network, server distinguish access permission and authorization of mobile device using acquiring the conetxt information of mobile device. By using this result, server applies the appropriate management technique to the mobile device for leakage and accident of internal network.

• Journal of Korean Physical Therapy Science
• /
• v.29 no.1
• /
• pp.41-46
• /
• 2022

Background: The purpose of this study was to develop a sit-to-stand transfer assistive device, and to conduct a feasibility test. Design: A technical note. Methods and results: In this study, we developed a sit-to-stand transfer assistive device for the elderly and the disabled who have difficulty standing up independently from sitting positions. The sit-to-stand transfer assistive device allows the user to transfer the weight from a sitting position to a standing position while shifting the weight forward by grabbing and pulling a support stand. Ten healthy adults participated in the feasibility test of the device. Each participant used the developed sit-to-stand transfer assistive device and investigated supplementation through a brief interview. As a result of the feasibility test, the opinion was that the device could assist the sit-to-stand transfer to some extent. There were opinions that it needed a function to adjust the height of the knee protective plate in the sitting position according to the user's physical characteristics. Because of the inconvenience of operating the lock device for fixing the position and adjusting inclination, there was an opinion that the improvement for a locking device is needed. There were opinions that it would be better to reduce the size of the device due to its inconvenience of portability. Conclusion: In this study, we developed the sit-to-stand transfer assistive device for the elderly and the disabled who have difficulty standing up independently from sitting positions. In addition, it is considered that the upgrade of the device is necessary for the future since there are supplementary opinions on some points.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3150-3155
• /
• 2007

This paper describes an experimental work to investigate the effect of mesh screen device on the jet structure and acoustic characteristics of over-expanded supersonic jet. The mesh screen device is placed into the supersonic jet stream. In order to perturb mainly the initial jet shear layer, the hole is perforated in the central part of the mesh screen. The diameter of the perforated hole and the location of mesh screen device are varied. A Schlieren optical system is used to visualize the flow fields of supersonic jet without and with the mesh screen device. Pitot pressure measurement is carried out to obtain the pressure distribution in the jet flow. Acoustic measurement also is performed to obtain the OASPL and noise spectra. The results obtained show that the jet structure and the jet noise control effectiveness is strongly dependent upon the diameter of the perforated hole and the location of the mesh screen device in the jet stream. Provided that the mesh screen device is placed at the location to perturb effectively the initial shear layer, the present control method is effective in suppressing the supersonic jet noise.

• The Journal of Korean Physical Therapy
• /
• v.30 no.4
• /
• pp.123-128
• /
• 2018

Purpose: This study examined the effects of neuromuscular electrical stimulation (NMES) and horseback riding using a robotic device on the trunk muscle activity and gross motor function in children with spastic diplegia. Methods: Children with spastic diplegia were divided into two groups: an experimental group (NMES and horseback riding using a robotic device [n=10]) and a control group (placebo NMES and horseback riding using a robotic device [n=10]). Each group received general physical therapy and occupational therapy. Each intervention involved the administration of NMES for 15 minutes and horseback riding using robotic device therapy for 15 minutes three times a week for 4 weeks. The evaluation included both the rectus abdominis muscles (RA), external oblique muscles (EO), thoracic paraspinal muscles (TP), and lumbar paraspinal muscles (LP) activity and GMFM. Results: The RA, EO, TP, and LP muscle activity, GMFM C, D, and E were increased significantly in the experimental and control groups. A significant increase in both the TP muscle activity and GMFM D was observed in the experimental group compared to the control group. Conclusion: This study showed that horseback riding using a robotic device is an effective intervention for trunk muscle activity and GMFM in children with spastic diplegia. However, if NMES is added to the back muscles, it is possible to further increase the thoracic paraspinal muscle activity and standing ability.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.684-687
• /
• 2004

We have developed multi-layer passivation films of UV-polymerized film/inorganic composite film to improve the long lifetime of passivated OLEDs for very thin flat panel applications. Preliminary lifetime to half initial luminance ($L_{o}{\sim}\;3,000\;cd/m^2$) of order 300 Hr is achieved on the conventional encapsulated test pixel using a passive matrix drive at room temperature; 570 Hr lifetime is achieved on a de tested multi-layer passivated 9$mm^2$ test pixel.

• The Korean Journal of Health Service Management
• /
• v.2 no.1
• /
• pp.28-36
• /
• 2008

The purpose of this study was effect that get to purchase decision-making factor of medical device decision making. A survey of 262 hospitals to 480 hospitals was conducted from December 3, 2007 to January 4, 2008 in the Busan area. The data generated in the survey was analyzed with SPSS/Win version 10.0 and appropriate tests and statistics including t-tests, ANOVA analyses were used. A summary of the actual results of this analysis are as follows : Of the 262 hospitals surveyed 249(95.1%) were male and 13(4.9%) were female, which shows an absolute higher ration of the male respondents. On a question of Medical device purchase sanction rise 50% occupy. CEO of a hospital($4.58{\pm}.80$) is highest at medical device purchase. The highest factor of medical device purchasing is picture quality($4.86{\pm}.37$), after service($4.84{\pm}.40$), cost($4.36{\pm}.75$). Through the results of the above study, Principle and department influence are put than human relations in the medical device purchase decision making.

• Journal of Electrical Engineering and Technology
• /
• v.7 no.5
• /
• pp.784-788
• /
• 2012

In this paper, a high-performance optical gating in a junction device based on a vanadium dioxide dioxide ($VO_2$) thin film grown by a sol-gel method was experimentally demonstrated by directly illuminating the $VO_2$ film of the device with an infrared light at ~1554.6 nm. The threshold voltage of the fabricated device could be tuned by ~76.8 % at an illumination power of ~39.8 mW resulting in a tuning efficiency of ~1.930 %/mW, which was ~4.9 times as large as that obtained in the previous device fabricated using the $VO_2$ thin film deposited by a pulsed laser deposition method. The rising and falling times of the optical gating operation were measured as ~50 ms and ~200 ms, respectively, which were ~20 times as rapid as those obtained in the previous device.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.3
• /
• pp.573-579
• /
• 2001

The technology for characteristic analysis of device for high integration is changing rapidly. Therefore to understand characteristics of high -integrated device by computer simulation and fabricate the device having such characteristics became one of very important subjects. As devices become smaller from submicron to nanometer, we have investigated MOSFET built on an epitaxial layer(EPI) of a heavily-doped ground plane by TCAD(Technology Computer Aided Design) to develop optimum device structure. We analyzed and compared the EPI device characteristics such as impact ionization, electric field and I-V curve with those of lightly doped drain(LDD) MOSFET. Also, we presented that TCAD simulator is suitable for device simulation and the scaling theory is suitable at nano structure device.

• Journal of Computing Science and Engineering
• /
• v.10 no.1
• /
• pp.32-38
• /
• 2016

Navigating a large 3D virtual environment using a generic haptic device can be challenging since the haptic device is usually bounded by its own physical workspace. On the other hand, mouse interaction easily handles the situation with a clutching mechanism-simply lifting the mouse and repositioning its location in the physical space. Since the haptic device is used for both input and output at the same time, in many cases, its freedom needs to be limited in order to accommodate such a situation. In this paper, we propose a new mechanism called Z-Clutching for 3D navigation of a virtual environment by using only the haptic device without any interruption or sacrifice in the given degrees of freedom of the device's handle. We define the clutching state which is set by pulling the haptic handle back into space. It acts similarly to lifting the mouse off the desk. In this way, the user naturally feels the haptic feedback based on the depth (z-direction), while manipulating the haptic device and moving the view as desired. We conducted a user study to evaluate the proposed interaction technique, and the results are promising in terms of the usefulness of the proposed mechanism.