• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.7B
• /
• pp.586-594
• /
• 2012

The drastic growth of mobile communication and spreading of smart phone make the significant attention on Location Based Service. The one of most important things for vitalization of LBS is the accurate estimating position for mobile object. Focusing on AP's probabilistic position estimation, we develop an AP distribution map and new pattern matching algorithm for position estimation. The developed approaches can strengthen the advantages of Radio fingerprint based Wi-Fi Positioning System, especiall on the algorithms and data handling. Compared on the existing approaches of fingerprint pattern matching algorithm, we achieve the comparable higher performance on both of average error of estimation and deviation of errors. Furthermore all fingerprint data have been harvested from the actual measurement of radio fingerprint of Seoul, Kangnam area. This can approve the practical usefulness of proposed methodology.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.8
• /
• pp.900-908
• /
• 2012

Owing to the proliferation of smart phone users, a proactive spectrum policy is needed in order to deal with increasing data traffic. Therefore, the prediction of frequency requirements for future wireless local area network (WLAN) as well as a licensed cellular communication is necessary. In this paper, we proposed a new prediction method for WLAN spectrum requirements. This method includes both a traditional prediction method and an offloading percentage from cellular network, Also, it can consider a frequency interference between access points using a statistical approach. Based on these approaches, we can predict the spectrum requirements of future domestic WLAN services considering the frequency interference. Finally, we suggest the spectrum policy for WLAN which can prevent spectrum shortage of future WLAN services.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.5
• /
• pp.646-651
• /
• 2012

This paper is about the experiment which is throughput of WLANs based on 802.11 due to interference each other. Recently, WLAN has been increased due to generalization of smart-phone and potable notebook. Therefore, the decrease of throughput because of interference between WLANs is expected. In regard of this, the throughput of WLANs according to channelling is measured in order to figure out efficient channelling and the throughput of WLANs according to the number of AP was measured in order to get relation between number of AP and throughput. Then, more efficient channelling of 1, 5, 9, 13 is suggested and the throughput of WLAN is decreased as increasing of number of AP.

• Journal of the Korean Institute of Gas
• /
• v.22 no.1
• /
• pp.53-59
• /
• 2018

In Korea, The number of installed LPG Charging stations is about 2000, increasing by 26 every year. In these, about 500 charging stations are older above 15 year, accounting about 25% of total stations. About 86% of them are located in the city, which is causing serious damage if accident occurs. In this paper, we developed a duel gas sensor module and integrated control system software that can prevent and correspondence to gas leaks and fire accidents at LPG/CNG charging stations. The dual type sensor module has the function of collecting and transmitting the measured data to the sensors of methane, butane and hydrogen through RF433Mhz communication. In addition, each sensor is attached with two to improve stability and accuracy. The integrated control system software detects real-time data of the devices measured by the sensors and it send to the PC and smart phone of manager. Therefore, if accident occurs, the manager can check the status of the charging station regardless of time and place.

• 대한공업교육학회지
• /
• v.39 no.1
• /
• pp.66-84
• /
• 2014

The purpose of this study is to develop STEAM hand-on activity task for middle school manufacturing & automation unit. This study was conducted following three stages. First of all, I carried out documents research and requirements analysis. And the goals for STEAM hand-on activity were set at this stage. Second, topics for STEAM hand-on activity were selected, and the organized for designing hand-on activity related STEAM in the development step. Finally, pilot and field test were conducted in order to amend and/or complement in improvement step. The theme and/or title of the hand-on activities were 'Making the print using wood', 'Making the close up photography & telephoto lens for smart phone'. The STEAM hand-on activities were designed for ten hours for each subject respectively. Each hand-on activity consists of problem situation, objectives statement, materials and tools, an evaluating criteria, related knowledge, portfolio and so on.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.30 no.3
• /
• pp.481-491
• /
• 2020

The malicious URLs which can be used for sending malicious codes and illegally acquiring private information is one of the biggest threat of information security field. Particularly, recent prevalence of smart-phone increases the possibility of the user's exposing to malicious URLs. Since the way of hiding the URL from the user is getting more sophisticated, it is getting harder to detect it. In this paper, after conducting a survey of the user experiences related to malicious URLs, we are proposing the rule-based malicious URL detection method. In addition, we have developed java library which can be applied to any other applications which need to handle the malicious URL. Each class of the library is implementation of a rule for detecting a characteristics of a malicious URL and the library itself is the set of rule which can have the chain of rule for deteciing more complicated situation and enhancing the accuracy. This kinds of rule based approach can enhance the extensibility considering the diversity of malicious URLs.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.2
• /
• pp.443-449
• /
• 2017

Opened platform is called that anybody can be a producer and consumer in some platform. And many opened platforms are using in various area such as general goods, smart phone application and contents. In this paper, we will propose the opened platform system for the problems for evaluation the level of learners. Any user can register problems as public or private-type in this system and use them. So our proposed system has the advantage in selecting the high quality problems by continuous reviews about that even after they have been registered. Proposed system has three different modules such as submit, evaluate and produce problems modules. A user can submit various kind of problems in the submit module. The evaluation module is a module that allows the user who is not the problem registrant to evaluate the registered problem. The production module can use the registered problems for online and offline evaluation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7893-7901
• /
• 2015

It is important to the periodic collection and analysis of the maintenance and management information of bridges for a more safe and efficient management of the bridges. To enhance the reliability and ease of acquisition of the bridge inspection information that is the basis for a strategy for safe and economic management using the bridge management system (BMS), this study develops a smart phone application for bridge inspection and ensures the actual applicability of the application. The developed application that is linked with the BMS for life-cycle management of bridges is possible to real-time query, modify and transmit of the maintenance-related information, and the application is able to greatly relieve the time and cost for the bridge inspection through the automatic creation of site inspection reports. The proposed method using the application is directly or indirectly expected to be very high effects of value improvement, such as ease of use, improved accuracy, sustainability of information, and future utilization, compared to conventional inspection method.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.1
• /
• pp.42-50
• /
• 2016

Recently, researches about the communication between LED array and the camera (alias 'Visual-MIMO'), have been actively conducted, and the application to the vehicle and a smart phone is expected to be maximized. Since the bit error may occur if the ISI is severe in a LED array, it is necessary to switch from the multiplexing to the diversity mode. In this paper, according to the use or not of a reference array pattern, a method for determining the transition time to the diversity mode is suggested and verified. When using the reference pattern, it determines the transition time to the diversity mode from the multiplexing using the brightness information of the received image. If the reference array pattern is not used, the size of LED array compared to the entire image according to the distance is used and the size of the LED array at the distance of a severe ISI may be used for the determination of transition time to the diversity. Finally, the proposed method is verified through the simulation and hardware experiments as well as by analyzing the performance in accordance with the ISI level and the distance.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.2
• /
• pp.178-188
• /
• 2016

The traffic in the wired and wireless networks has increased exponentially because of increase of smart phone and improvement of PC performance. Multimedia services and file transmission such as Facebook, Youtube occupy a large part of the traffic. CDN is a technique that duplicates the contents on a remote web server of content provider to local CDN servers near clients and chooses the optimal CDN server for providing the content to the client in the event of a content request. In this paper, the content request message between CDN servers and the client used the SCRP algorithm utilizing the MST algorithm and the traffic throughput was optimized. The average response time for the content request is reduced by employing HC_LRU cache algorithm that improves the cache hit ratio. The proposed SCRP and HC_LRU algorithm may build a scalable content delivery network system that efficiently utilizes network resources, achieves traffic localization and prevents bottlenecks.