• Journal of Internet Computing and Services
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• v.20 no.5
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• pp.95-104
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• 2019

Various kinds of devices are used for the Internet of Things (IoT) service, and IoT devices mainly use communication technology that uses the frequency of the unlicensed band. There are several types of communication technology in the unlicensed band, but WiFi is most commonly used. Devices used for IoT services vary in computing resources from devices with limited capabilities to smartphones and provide services over wireless networks such as WiFi. Most IoT devices can't perform complex operations for network control, thus they choose a WiFi access point (AP) based on signal strength. This causes a decrease in IoT service efficiency. In this paper, an intelligent AP system that can efficiently control the WiFi connection of the IoT devices is implemented. Based on the network information measured by the IoT device, the access point learns using a feed forward neural network algorithm, and predicts a network connection state to control the WiFi connection. By controlling the WiFi connection at the AP, the service efficiency of the IoT device can be improved.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.69.4-70
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• 2018

KAOS30 is an automatic observing software for the wide-field 10-inch telescope as a piggyback system on the 30-inch telescope at the McDonald Observatory in Texas, US. The software has four packages in terms of functionality and is divided into communication with Telescope Control System (TCS), controlling of CCD camera and filter wheel, controlling of focuser, and script for automation observing. Each interconnect of those are based on exe-exe communication. The advantage of this distinction is that each package can be independently maintained for further updates. KAOS30 has an integrated control library that combines function library connecting each device and package. This ensures that the software can extensible interface because all packages are access to the control devices independently. Also, the library includes the ASCOM driver platform. ASCOM is a standard general purpose library that supports Application Programming Interface (API) of astronomical devices. We present the software architecture of KAOS30, and structure of interfacing between hardware and package or package and package.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1080-1088
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• 2018

General methods of controlling a drone are divided into manual control and automatic control, which means a drone moves along the route. In case of manual control, a man should be able to figure out the location and status of a drone and have a controller to control it remotely. When people control a drone, they collect information about the location and position of a drone with the eyes and have its internal information such as the battery voltage and atmospheric pressure delivered through telemetry. They make a decision about the movement of a drone based on the gathered information and control it with a radio device. The automatic control method of a drone finding its route itself is not much different from manual control by man. The information about the position of a drone is collected with the gyro and accelerator sensor, and the internal information is delivered to the CPU digitally. The location information of a drone is collected with GPS, atmospheric pressure sensors, camera sensors, and ultrasound sensors. This paper presents an investigation into drone control by a remote computer. Instead of using the automatic control function of a drone, this approach involves a computer observing a drone, determining its movement based on the observation results, and controlling it with a radio device. The computer with a Depth camera collects information, makes a decision, and controls a drone in a similar way to human beings, which makes it applicable to various fields. Its usability is enhanced further since it can control common commercial drones instead of specially manufactured drones for swarm flight. It can also be used to prevent drones clashing each other, control access to a drone, and control drones with no permit.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.58-66
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• 2006

Environmental Sensitivity Index Map(ESI Map) is useful information for efficient and prompt contolling of oil spill accident. Environmental sensitivity information relating to oil spill is very various, so efficient access and utilization for environmental sensitivity information at control field is required. In order to improve the efficiency of controlling accident at the field, it is necessary to building digital ESI Map and GIS program. In this study, GIS database was built to utilize environmental sensitivity information at Yeosu and Gyunggi bay. And the ESI Map program which is focused on the control job was developed. IMO/IPIECA's guide to make the ESI Map and Korea Coast Guard's guide to collect information for the control information map were referenced to capture environmental sensitivity data and build GIS database. The symbology of environmental sensitivity layers was defined and functions for supporting control job were implemented in ESI Map program. For the future works, the program in this study could be applied to ESI Map program for the whole coastal area of Korea and it could be the essential element technology in marine pollution control supporting system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1A
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• pp.65-71
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• 2006

In IEEE 802.11b wireless network, the access point(AP) sends beacons periodically to manage stations when they are running in low power mode. Stations contend for the transmission medium after they receive a beacon and continuously check its state until it becomes available. Thus the energy consumption of each station increases as the load of wireless network. In this paper, we propose a method to reduce energy consumption controlling virtual bitmap in wireless network with multiple stations. The problems of low power mode in IEEE 802.11b wireless interface are described and a new method to reduce energy consumption is proposed. The proposed method is simulated with the network simulator, ns2, and compared with the low power mode of the IEEE 802.11b. The result measured in terms of station's wakeup time shows some enhancement in energy consumption when multiple stations are communicating through the AP in wireless network.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.677-684
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• 2017

Smart devices are used in a variety of industries, because applications for them are easy to develop and portable. However, industrial equipment can cause security problems for information and accidents when controlling the actuator of the equipment at a remote location. In this paper, we studied methods of solving these problems and the advantages of applying smart control systems to industrial equipment. We propose a manual manipulation method using queries and a smart control access procedure for controlling equipment using a smart device. In addition, we propose a data transmission method employing multiple encryption protocols and a user authentication method using unique information from the smart device and Q & A as the communication data protection and user authentication methods, respectively. In order to evaluate its performance, an operation test of the smart control system and user authentication comparison experiment were performed. In order to understand the advantages of applying the smart control system to the equipment, we conducted a comparative experiment with a teach pendant and evaluated its reaction time in case of error.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.259-265
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• 2007

Systematic components for implementing ubiquitous computing, for example, electronic devices, electric home appliances, and controllers, etc, are consist of not only circuits but also softwares expected to do some special system-controlling functions, and these softwares used to be called like as embedded software. Because embedded software is a core component controlling systems, the codes or control flows should be protected from being opened to the public or modified. Embedded software security can be divided into 2 parts: first is the unauthorized access to development site and embedded software, second is the unauthorized disclosure or modification. And this research is related to the first aspect of them.This paper proposes some security check requirements related to embedded software development site by analyzing the ALC_DVS.1 of the ISO/IEC 15408 and Base Practices (BPs) of the ISO/IEC 21827. By applying this research, we expect to protect unauthorized modification of embedded software indirectly.

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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• pp.77-84
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• 2015

The purpose of this study is to interpret Landscape of Naeap Village which still preserves the Confucian culture and the traditional clans among the ideally settled villages mentioned in Joong Hwan Lee's "Taengniji" and "Joseon's Fengsui" from the time of Japanese Imperial Rule, from CPTED principles. The following are the findings of this study: First, in terms of access control and zoning, Naeap Village was controlling access from the outside with the natural environment of Banbyeoncheon River and the hills surrounding the village, the artificial environment of human-scale walls around the head house and the dead ends, and the reformation by the Confucian ideologies. Naeap Village, in particular, is prominently configured by the hierarchy of zones; the Gaehosong pine trees, Gyeongpodae, and Naeapssu by the entrance to the village are considered the village itself and the landscapes and valleys are managed by the head house. Second, the Confucian culture across the village, the traditional vegetation method that does not hide the visibility, and the workers in the farms allow natural monitoring. The surrounding visibility is also applied to the spirit of mutual cooperation in the farming society, the culture of commoners at the common well and laundry site, and the culture of ruling class at the towers and pavilions. Third, Traditional villages show the efforts to preserve and maintain the villages with the village rules, the organizational decrees of the clan, and active response to national disasters.

• International Journal of Railway
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• v.3 no.2
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• pp.39-45
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• 2010

The RF-CBTC (Radio Frequency-Communication Based Train Control) System is a communication system in railroad systems. The communication method of RF-CBTC system is the wireless between the wayside device and on-board device. The wayside device collects its location and speed from each train and transmits the distance from the forwarding train to the speed-limit position to it. The on-board device controlling device controls the speed optimum for the train. In the case of the RF-CBTC system used in Korea, transmission frequency is 2.4 [GHz]. It is the range of ISM(Industrial Scientific and Medical equipment) band and transmission of voice and data is performed by CDMA (Code Division Multiple Access) method. So noises are made in the AWGN (Additive White Gaussian Noise) and fading environment. Currently, the SNR (Signal to Noise Ratio) is about 20 [dB], so due to bit errors made by noises, transmission of reliable information to the train is not easy. Also, in the case that two tracks are put to a single direction, it is needed that two trains transmit reliable voice and data to a wayside device. But, by noises, it is not easy that just a train transmits reliable information. In this paper, we estimated the BER (Bit Error Rate) related to the SNR of voice and data transmission in the environment such as AWGN and fading from the RF-CBTC system using the CDMA method. Also, we supposed the SNR which is required to meet the BER standard for voice and data transmission. By increasing the processing gain that is a ratio of chip transmission to voice and data transmission, we made possible voice and data transmission from maximally two trains to a wayside device, and demonstrated it by using Matlab program.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.683-701
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• 2012

IEEE 802.11 standard has achieved huge success in the past decade and is still under development to provide higher physical data rate and better quality of service (QoS). An important problem for the development and optimization of IEEE 802.11 networks is the modeling of the MAC layer channel access protocol. Although there are already many theoretic analysis for the 802.11 MAC protocol in the literature, most of the models focus on the saturated traffic and assume infinite buffer at the MAC layer. In this paper we develop a unified analytical model for IEEE 802.11 MAC protocol in ad hoc networks. The impacts of channel access parameters, traffic rate and buffer size at the MAC layer are modeled with the assistance of a generalized Markov chain and an M/G/1/K queue model. The performance of throughput, packet delivery delay and dropping probability can be achieved. Extensive simulations show the analytical model is highly accurate. From the analytical model it is shown that for practical buffer configuration (e.g. buffer size larger than one), we can maximize the total throughput and reduce the packet blocking probability (due to limited buffer size) and the average queuing delay to zero by effectively controlling the offered load. The average MAC layer service delay as well as its standard deviation, is also much lower than that in saturated conditions and has an upper bound. It is also observed that the optimal load is very close to the maximum achievable throughput regardless of the number of stations or buffer size. Moreover, the model is scalable for performance analysis of 802.11e in unsaturated conditions and 802.11 ad hoc networks with heterogenous traffic flows.