• Korean Journal of Optics and Photonics
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• v.26 no.3
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• pp.168-171
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• 2015

The heat flow characteristics of a high-power optical semiconductor source have been analyzed using a 3D CFD commercial tool, and the thermal resistance values for each of the layers revealed the places for thermal bottlenecks to be improved. As the heat source of a LD (Laser Diode) has a small volume and a narrow surface, the effective thermal cross-sectional area near it is also quite small. It was possible to expand the cross-sectional area effectively by using graphene layers on the TIM (Thermal Interface Material) layers of a LD chip. The effective values of heat resistance for the layers are compared to confirm the improvement effect of the graphene layers before and after, which can be considered to expand the thermal cross section of the heat transfer path.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.173-176
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• 2008

Use of concrete has undoubtedly become widespread in construction. Sensors are used to add functional characteristics to concrete. Self-diagnosing, smart concrete is also being developed. Development of these functional materials and structures will play an important role in protecting buildings and structures against external factors brought about by unusual weather among others. In this study, the innovative measurement system is presented where material damages and internal stress can simply be detected against the compressive and bending force of the structure using light-emitting diode and the resistance property of electric fuse.

• Smart Media Journal
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• v.13 no.5
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• pp.19-25
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• 2024

The biggest type of behavior that prevents people with developmental disabilities from entering society is aggressive behavior. Aggressive behavior can pose a threat not only to the personal safety of the person with a developmental disability, but also to the physical safety of others. In this study, we propose a wearable system using a low-power processor. The proposed system uses an IMU (Inertial Measurement Unit) to analyze user behavior, and when attack behavior is not detected for a certain period of time through an LED array attached to the developed system, an interesting LED is displayed. By expressing patterns, we provide behavioral intervention through compensation to people with developmental disabilities. In order to implement a system that must be worn for a long time in a power-limited environment, we present a method to optimize performance and energy consumption across all stages, from data preprocessing to AI model application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.5
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• pp.486-493
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• 2024

Lighting has been used for a long time as a medium to convey brightness from darkness, and through incandescent lamps and fluorescent lamps, LED light sources have now become the standard in the lighting industry. Recently, the lighting equipment industry has been undergoing rapid digital transformation, starting with smart lighting, and is evolving into smart lighting customized for individuals and spaces through the development of IoT technology, cloud-based services, and data analysis. However, the blue light emitted from digital devices (computers, smartphones, tablets, etc.) or LED lights stimulates the melanopsin in the optic ganglion cells in the retina of the eye, which in turn stimulates the secretion of melatonin through the pineal gland, which regulates the secretion of melatonin. This can reduce sleep quality or disrupt biological rhythms. This interaction between blue light and melatonin has such a significant impact on human sleep patterns and overall health that it is essential to reduce exposure to blue light, especially in the evening. Human-centered lighting refers to lighting that takes into account the effects of light on the physical and mental areas, such as human activity and awakening, improvement of sleep quality, and health management. Many research institutes study the effects in the visible area and the non-visible area. By studying the impact, it is expected to improve the quality of human life. In this study, we plan to study ways to implement human-centered lighting by collecting sunrise and sunset data and linking commercialized LED packages and control devices with open-source hardware.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.8-14
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• 2020

Recently, there was an increasing demand for an integrated access control system which is capable of user recognition, door control, and facility operations control for smart buildings automation. The market available door lock access control solutions need to be improved from the current level security of door locks operations where security is compromised when a password or digital keys are exposed to the strangers. At present, the access control system solution providers focusing on developing an automatic access control system using (RF) based technologies like bluetooth, WiFi, etc. All the existing automatic door access control technologies required an additional hardware interface and always vulnerable security threads. This paper proposes the user identification and authentication solution for automatic door lock control operations using camera based visible light communication (VLC) technology. This proposed approach use the cameras installed in building facility, user smart devices and IoT open source controller based LED light sensors installed in buildings infrastructure. The building facility installed IoT LED light sensors transmit the authorized user and facility information color grid code and the smart device camera decode the user informations and verify with stored user information then indicate the authentication status to the user and send authentication acknowledgement to facility door lock integrated camera to control the door lock operations. The camera based VLC receiver uses the artificial intelligence (AI) methods to decode VLC data to improve the VLC performance. This paper implements the testbed model using IoT open-source based LED light sensor with CCTV camera and user smartphone devices. The experiment results are verified with custom made convolutional neural network (CNN) based AI techniques for VLC deciding method on smart devices and PC based CCTV monitoring solutions. The archived experiment results confirm that proposed door access control solution is effective and robust for automatic door access control.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.48-54
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• 2020

Researchers recognized air pollution changes causing diseases and difficulties in living due to environmental pollution following various human activities, and have studied how to avoid fine dust harmful to the human respiratory system to be healthy. To this end, Arduino is used to equip fine dust level sensors in drones to measure the fine dust levels, visualize the measurements with LED indicator colors depending on the measurements to inform users of the danger of fine dust, and use the benefits of drones to specify dangerous fine dust zones and measure the fine dust levels. Users can see the changes depending on the fine dust levels in real time with the LED indicators. This will contributes to measuring fine dust levels easily in dangerous areas. Mission Planner (ArduPilot) is used to set up the GPS of drone, and store the data from the dust sensor as contents. This study aims to establish a method for improving the environment to measure fine dust levels with drones with LED indicators for fine dust, and reduce fine dust.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.74-79
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• 2014

Illumination is an effective technique that must be in the mankind today. These lights, there is artificial light that is created by using an artificial light source daylight illumination by sunlight, in this paper, it is created using the electrical energy it is a paper on the study of technology management scheme and efficient control technology of artificial light.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.533-535
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• 2018

In the 21st century, in which the accident rate is rapidly increasing in proportion to the development of automobiles, In order to reduce the number of accidents, this paper was written for the convenience of the elderly people with disabilities and the handicapped. When a driver's safety accidents and various signals are transmitted through a smart phone by voice, the voice signal is processed as a video signal through the rear LED pannel of the vehicle, so that an urgent situation or a current state can be clarified It is also possible to use the local area network as a billboard and I would like to propose a study to show the advertising effect and current traffic situation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2297-2304
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• 2016

In this study, we designed and developed the virtual reality Exergame using the smart mat and the camera sensor for exercises in indoor environments. For detecting the gestures of a upper body of users, the KINECT camera based the gesture recognition algorithm used angles between user's joint information system was adopted, and the smart mat system including a LED equipment and Bluetooth communication module was developed for user's stepping data during the exercises that requires the gestures and stepping of users. Finally, the integrated virtual reality Exergame system was implement along with the Unity 3D engine and different kinds of user' virtual avatar characters with entertainment game contents such as displaying gesture guideline and a scoring function. Therefore, the designed system will useful for elders who need to improve cognitive ability and sense of balance or general users want to improve exercise ability and the indoor circumstances such home or wellness centers.

• Korean Journal of Ecology and Environment
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• v.53 no.3
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• pp.304-310
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• 2020

Smart farm is a high-tech type of plant factory that artificially makes environmental conditions suitable for the growth of plants and manages them to automatically produce the desired plants regardless of seasons or space. This study was conducted by identifying the effects of Hertz and Duty ratio on the photosynthetic rate of ginseng, a medicinal crop, to find the optimal conditions for photosynthetic responses in smart farms. The light sources consisted of a total of 10 chambers using LED system, with 4 R+B(red+blue) mixed lights and 6 R+B+W (red+blue+white) mixed lights. In addition, the Hertz of the R+B mixed light was treated at 20, 60, 180, 540, 1620 and 4860 hz respectively. The R+B+W mixed light was treated with 60, 180, 540, and 1620 hz. Afterwards, experiments were conducted with the duty ratio of 30, 50, and 70%. As a result, the photosynthetic rate of ginseng according to duty ratio and Hertz was the highest at 60 hz when duty ratio was set to 50%. On the other hand, that was the lowest when the duty ratio was 30% at the same 60 hz. In addition, the photosynthetic rates were highest in the R+B mixed light and R+B+W mixed light at 60 hz. Therefore, the condition with the highest photosynthetic rate of ginseng in smart farms is 60 hz when the duty ratio in R+B mixed light is 50%.