• Journal of Korea Society of Industrial Information Systems
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• v.26 no.4
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• pp.11-18
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• 2021

We propose a method that combines learning in a virtual environment and a real environment for indoor autonomous driving through reinforcement learning. In case of learning only in the real environment, it takes about 80 hours, but in case of learning in both the real and virtual environments, it takes 40 hours. There is an advantage in that it is possible to obtain optimized parameters through various experiments through fast learning while learning in a virtual environment and a real environment in parallel. After configuring a virtual environment using indoor hallway images, prior learning was carried out on the desktop, and learning in the real environment was conducted by connecting various sensors based on Jetson Xavier. In addition, in order to solve the accuracy problem according to the repeated texture of the indoor corridor environment, it was possible to determine the corridor wall object and increase the accuracy by learning the feature point detection that emphasizes the lower line of the corridor wall. As the learning progresses, the experimental vehicle drives based on the center of the corridor in an indoor corridor environment and moves through an average of 70 steering commands.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.1
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• pp.7-21
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• 2017

Multiple antenna techniques employed in fourth generation mobile communication systems are affected on their performance mostly by transmission environments and antenna configurations. The performance of the indoor LTE(Long-term Evolution) MIMO(multiple input multiple output) has been rigorously evaluated with considering various diversity transmission schemes and propagation conditions in the paper. Specifically, MAC TP(medium access control throughput) and LTE system parameters related to the MIMO technique are analyzed for several indoor propagation conditions. The performance comparison between multiple antenna diversity mode and single antenna mode has been derived as well. The results performed in the paper give the guideline on antenna configurations of polarization diversity in LTE 2×2 MIMO for various indoor channel environments, and possibly are exploited by network operators and antenna manufacturers.

• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.627-636
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• 2023

Due to the COVID-19 pandemic, the global population has experienced drastic changes, one of which is the increase in remote work. Given the ongoing possibility of exposure to infectious diseases and various other circumstances, the expansion of remote work is anticipated. To enhance the efficiency of remote work and address its existing limitations, this study surveyed the perceptions of indoor environments among individuals who worked from home during the COVID-19 pandemic. The study examined how the characteristics of individuals influenced their perceptions of indoor environments. It was found that the number of occupants and rooms, size of the house, and noise sensitivity affected the perceptions of outdoor noise, neighbor noise, and indoor noise caused by cohabitants. The findings can be used as foundational data for designing multipurpose housing that can be utilized not only for residential purposes but also for work and educational settings in the future.

• Journal of the Korea Computer Industry Society
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• v.3 no.5
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• pp.547-556
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• 2002

This paper was proposed a wave path loss prediction algorithm using multilayer perceptron (MLP) model and wave propagation characteristic parameters for Wireless LAN in indoor radio environments. Receiving power was predicted by calculating indoor path loss in a Wireless LAN that has transmission power of 100mW and frequency of 2.4GHz, and was compared with measured. In the result of measurement shows that there is a difference between predicted and measured receiving power which can be reduced by an accurate analysis of the various path loss factors. In order to fix the access point(AP) positions was used the proposed a wave path loss prediction algorithm, and designed the optimum cell for Wireless LAN.

• The KIPS Transactions:PartB
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• v.19B no.3
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• pp.177-182
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• 2012

We propose effective motion and observation models for the position of a WiFi-equipped smartphone user in large indoor environments. Three component motion models provide better proposal distribution of the pedestrian's motion. Our Gaussian interpolation-based observation model can generate likelihoods at locations for which no calibration data is available. These models being incorporated into the particle filter framework, our WiFi fingerprint-based localization algorithm can track the position of a smartphone user accurately in large indoor environments. Experiments carried with an Android smartphone in a multi-story building illustrate the performance of our WiFi localization algorithm.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.1
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• pp.122-131
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• 1999

Indoor environments are usually less than optimal for the growth of ferns, especially in regards to the water condition. These studies were performed to investigate responses involved in causing growth of ferns and presume management plan against the water deficit under indoor conditions. The effect of air humidity and soil moisture on the ferns was examined in Adiantume raddianum and Selaginella kraussiana. Results of experiments are as follows; 1. Under a low humidity condition, having a 25-50% RH. ornamental value of ferns decreased much more than under a 90% RH. Under a low soil moisture, such as sand treatment, ornamental value of ferns also decreased. 2. Leaf chlorophyll content, water content and stomata situations increased as air humidity and soil moisture went up. 3. Even if air humidity and soil water were not enough for ferns growth, the extending of irrigation cycle was helpful. 4. Under extremely low air humidity conditions, some water management, namely, using water holding soil or extending of irrigation cycle was desirable. Other methods of increasing air humidity, including water instruments such as ornamental pools, waterfalls, or fountains, grouping plants together were also helpful. But spraying water on leaves increased injury to ferns growth because of excess evaporation from the leaves. Though these studies, we learn that ferns are susceptible to water condition such as air humidity, soil water and water management. If other environmental factos are maintained with optimal conditions, water condition plays an important role in ferns growth in indoor environments.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.5
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• pp.281-296
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• 2015

This paper describes a novel disaster evacuation system using embedded systems such as smart devices for crisis and emergency management. In indoor environments deployed with the Bluetooth Low Energy(BLE) beacons, smart devices detect their indoor positions from beacon messages and interact with Map Server(MS) and Route Server(RS) in the Internet over the LTE and/or Wi-Fi functions. The MS and RS generate an optimal path to the nearest emergency exit based on a novel graph generation method for less route computation, called the Disaster Evacuation Graph(DEG), for each smart device. The DEG also enables efficient processing of some constraints in the computation of route, such as load balancing in situation of different capacities of paths or exits. All data interfaces among three system components, the MS, RS, smart devices, have been defined for modular implementation of our disaster evacuation system. Our experimental system has been deployed and tested in our building thoroughly and gives a good evidence that the modular design of the system and a novel approach to compute emergency route based on the DEG is competitive and viable.

• The Journal of Korea Robotics Society
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• v.18 no.4
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• pp.487-495
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• 2023

This paper presents a method for autonomous exploration of indoor environments using a 2-dimensional Light Detection And Ranging (LiDAR) scanner. The proposed frontier-based exploration method considers navigability from the current robot position to extracted frontier targets. An approach to constructing the point cloud grid map that accurately reflects the occupancy probability of glass obstacles is proposed, enabling identification of safe frontier grids on the safety grid map calculated from the point cloud grid map. Navigability, indicating whether the robot can successfully navigate to each frontier target, is calculated by applying the skeletonization-informed rapidly exploring random tree algorithm to the safety grid map. While conventional exploration approaches have focused on frontier detection and target position/direction decision, the proposed method discusses a safe navigation approach for the overall exploration process until the completion of mapping. Real-world experiments have been conducted to verify that the proposed method leads the robot to avoid glass obstacles and safely navigate the entire environment, constructing the point cloud map and calculating the navigability with low computing time deviation.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.05a
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• pp.259-263
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• 2006

The purpose of this study is to assess the characteristics of self-reported symptoms of workers in office building with HVAC system, and also to provide better workplaces in terms of comfort and health. The methods employed in this study include literature review, field observations, and survey. The self-reported symptoms of workers such as headache, fatigue, itching and dryness regarded as SBS symptoms commonly occur after around 3:00 pm and are relieved after leaving their office buildings. according to results in previous studies, above are possibly related to CO2 concentrations. It is also found work environment factors and the satisfaction on indoor environment are all associated with worker's health. Hopefully, this overview of current work environments concerning the level of satisfaction and health problems of workers would help create healthier indoor environment.

• Journal of Korean society of Dental Hygiene
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• v.14 no.2
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• pp.197-204
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• 2014

Objectives : The purpose of the study is to examine the effect of the indoor environmental factors of dental hygienists on physical symptoms. Methods : The subjects were 210 dental hygienists in dental hospitals and clinics in Seoul, Gyeonggi Province, Incheon and South Chungnam Province from May 1 to June 20, 2013. Results : There were significant differences between the presence or absence of windows in respiratory symptoms and eye symptoms. Room temperature, bad smell, and dry humidity had significant influences on physical and respiratory symptoms. Dermatological and ophthalmological symptoms were affected by dryness, smell and dusts. Dusts and bad smell also had influences on a variety of subjective symptoms. Conclusions : The indoor environments of dental hospitals and clinics affect the respiratory, dermatological, and ophthalmological symptoms because various hazardous materials are generated by the dental treatment. Therefore dental hygienists should have a correct understanding of bacteria, dusts and bio-aerosol in order to ensure the successful environmental control.