• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.625-630
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• 2011

In this paper, spiral meander monopole printed antenna for dual band operation in GPS(1.57~1.577 GHz) and WiBro(2.3~2.4 GHz), WLAN(2.4~2.48 GHz) is proposed. Spiral(positive coupling) mounted end of monopole(small current) and meander mounted fed of monopole(big current) for reduce frequency ratio. Bandwidth(-10 dB) of the antenna is measured 130 MHz(1.49~1.62 GHz) in basic resonance frequency and 330 MHz(2.29~2.62 GHz) in harmonic resonance frequency($3{\lambda}_H/4$). The peak antenna gains are measured 2.86 dBi in GPS(1.57 GHz), and 3.49 dBi in WiBro(2.35 GHz), and 3.71 dBi in WLAN(2.44 GHz).

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.257-266
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• 2009

Now a days, as increased the use of mobile units like a laptop computer and PDA, the demand for high speed internet service is increasing. On the other hand, PKMv2 which is provided from IEEE 802.16e cannot support fully on the security of high speed internet service. This paper proposes light-weight mutual authentication protocol which solved security problem of PKMv2 related to integrity of mobile node for transmission of safe high speed data of mobile node operating in mobile WiMAX environment. Proposed mutual authentication protocol increases the efficiency as the user in network can move in network safely without additional procedure of authentication between subscriber and base station after user's initial authentication. Also, the proposed mutual authentication protocol is safe from the security attack (the man-in-the-middle attack and reply attack) between subscriber and base station by generating a key adopt to PRF() function using random number and secret value in order to secure certification.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.782-791
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• 2021

Objective: To evaluate the signal intensity of the periosteum using ultrashort echo time pulse sequence with three-dimensional cone trajectory (3D UTE) with or without fat suppression (FS) to distinguish from artifacts in porcine tibias. Materials and Methods: The periosteum and overlying soft tissue of three porcine lower legs were partially peeled away from the tibial cortex. Another porcine tibia was prepared as three segments: with an intact periosteum outer and inner layer, with an intact periosteum inner layer, and without periosteum. Axial T1 weighted sequence (T1 WI) and 3D UTE (FS) were performed. Another porcine tibia without periosteum was prepared and subjected to 3D UTE (FS) and T1 WI twice, with positional changes. Two radiologists analyzed images to reach a consensus. Results: The three periosteal tissues that were partially peeled away from the cortex showed a high signal in 3D UTE (FS) and low signal on T1 WI. 3D UTE (FS) showed a high signal around the cortical surface with an intact outer and inner periosteum, and subtle high signals, mainly around the upper cortical surfaces with the inner layer of the periosteum and without periosteum. T1 WI showed no signal around the cortical surfaces, regardless of the periosteum state. The porcine tibia without periosteum showed changes in the high signal area around the cortical surface as the position changed in 3D UTE (FS). No signal was detected around the cortical surface in T1 WI, regardless of the position change. Conclusion: The periosteum showed a high signal in 3D UTE and 3D UTE FS that overlapped with artifacts around the cortical bone.

• Journal of the Korean Institute of Gas
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• v.25 no.3
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• pp.46-52
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• 2021

In this study, the on-site location identification and response system was proposed by accurately checking the location information of rescue requesters in the buildings using the smartphone Wi-Fi AP. The location server was requested to measure the strength of the Wi-Fi AP at least 25 times at 8 different building location points. And the accuracy of the position and the error range were checked by analyzing the coordinate values of the received positions. In addition, the response time was measured by changing the conditions of location information in three groups to compare the response time for saving lives with and without location information. The minimum and maximum error values for the eight cases were found to be at least 4.137 m and up to 14.037 m, respectively, with an average error of 9.525 m. Compared to the base transceiver station (BTS) based position error value of 263m, the range could be reduced by up to 93%. When the location information was given, it took 10 minutes and 50 seconds to save lives; however, when there was no location information at all, rescue process took more than 45 minutes. From this research effort, it was analyzed that the acquisition of the location information of rescuees in the building using the smartphone Wi-Fi AP approach is effective in reducing the life-saving time for on-site responses.

• Journal of Information Technology Applications and Management
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• v.26 no.5
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• pp.41-56
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• 2019

Recently great loss of life and property is occurring because of fire, natural disaster, earth quake, tsunami and so on. People spend 80~90% of their time indoor environment like office, supermarket, campus. Therefore Indoor navigation and guidelines system became so essential for most of all. Incase of emergency we must be careful earlier, in such a cases 5G kind of new technology may also cannot work. So immediate action and quick routing notification for guidelines and protection is the most. Considering this issue We proposed indoor evacuating guidance system based on microcontroller Wi-Fi board for Indoor APP using mobile. Focusing various kind of technology like, ok google, voice search APP we purposed node architecture based system. When we listen fire alarm while living inside the room. Then to be safe we connect with server and start Arduino UNO+IoT ESP8266 Wi-Fi shield version1-IoT module to store data in MySQL DB server. We make application to escape out from the building up-to the three exits giving information from source point to destination. Our program can send information to the users emergency location and situations. For this when the user get sound or vibration in their mobile device it indicate fire out near by. At that time we update message from Arduino to DB server for the fixed current position inside the building which give routing signal for that fire out location by changing values from 0 to 1. We have user in point 10 where user is near by. Later we detect Wi-Fi signal form Nodemcu as room of each floor and try to connect with user. Main purpose of this paper is to save life of people in short time and find out the shortest path up to nearest exits in the time of emergencies and rescue them.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.129-134
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• 2018

Research on the technique for estimating the indoor position has been actively carried out. In particular, the WiFi fingerprint method, which does not require any additional infrastructure, is being partially used because of its high economic efficiency. The KNN method which estimates similar points to the corresponding points by comparing intensity information of the WLAN reception signal measured at various points in advance with intensity information measured at a specific point in the future is simple but has a good performance. However, in the conventional KNN scheme, since the number K of average candidate positions is constant, there is a problem that the position estimation error is not optimized according to a specific point. In this paper, we proposed an algorithm that adaptively changes the K value for each point and applied it to experimental data and evaluated its performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.645-647
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• 2015

IoT (Internet of Things) technology has immense potential in our modern society. Generally when used in a consumer electronics environment, the IoT can continue to work more efficiently than the conventional method of home appliances. In order to use the IOT device's effectively in the environment, we need to determine the relationship between all device's based on their state and priority and compare it to find the suitable device based on the state and priority. In this paper I have done research on Wi-Fi devices in a network environment and I have observed relationships between them. Also I have proposed an algorithm to determine the device status and priority. This determines high-priority devices and they are identified on the basis of the state of the device associated with a particular operation and proceeds further.

• Korean Journal of Food Science and Technology
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• v.51 no.4
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• pp.343-347
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• 2019

This study was performed to develop an economical culture method of lactic acid bacteria (LAB) for kimchi fermentation. Leuconostoc mesenteroides WiKim32 was grown to $1{\times}10^9CFU/mL$ and maintained at 8.88 log CFU/mL for four days by culturing in kimchi cabbage juice (KCJ) without supplements and sterilization. Leuconostoc mesenteroides WiKim32 was cultured in 100 mL of KCJ by inoculating with 0.1% starter culture and adding 100 mL of KCJ everyday by adjusting pH to 5.5 using 1 M NaOH at $20^{\circ}C$ for four days. KCJ was prepared by extraction of kimchi cabbage leaves after washing them with citric acid and ethanol. Adjusting pH over 6.0 was favorable for the growth of LAB in the initial stage, but LAB growth was retarded in the later stage. In contrast, adjusting pH below 5.0 was not beneficial for the growth of LAB; therefore, pH was adjusted to 5.5.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1583-1588
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• 2022

In this study, we investigated the effect of lactic acid bacteria (LAB) strains used as starters for kimchi fermentation, namely Lactococcus lactis WiKim0124, Companilactobacillus allii WiKim39, Leuconostoc mesenteroides WiKim0121Leuconostoc mesenteroides WiKim33, and Leuconostoc mesenteroides WiKim32, on the intestinal epithelial tight junctions (TJs). These LAB strains were not cytotoxic to Caco-2 cells at 500 ㎍/ml concentration. In addition, hydrogen peroxide (H₂O₂) decreased Caco-2 viability, but the LAB strains protected the cells against H₂O₂-induced cytotoxicity. We also found that lipopolysaccharide (LPS) promoted Caco-2 proliferation; however, no specific changes were observed upon treatment with LAB strains and LPS. Our evaluation of the permeability in the Caco-2 monolayer model confirmed its increase by both LPS and H₂O₂. The LAB strains inhibited the increase in permeability by protecting TJs, which we evaluated by measuring TJ proteins such as zonula occludens-1 and occludin, and analyzing them by western blotting and immunofluorescence staining. Our findings show that LAB strains used for kimchi fermentation can suppress the increase in intestinal permeability due to LPS and H₂O₂ by protecting TJs. Therefore, these results suggest the possibility of enhancing the functionality of kimchi through its fermentation using functional LAB strains.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1138-1143
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• 2013

In this paper, we propose a smartphone application based on a wireless fidelity(WiFi) in order to control the charging of electric vehicle(EV) and monitor the charging status together with the vehicle history information. The driver obtains much information on vehicle status through a smartphone application which communicates with the electric vehicle supply equipment(EVSE) management server while the EV also communicates with the EVSE for the authentification through controller area network(CAN). We also implement the simulator for the EV charging control system to verify the functions of the proposed application where the simulator consists of an EV model, an EVSE, and a smartphone. It is shown by the simulator that the proposed smartphone application allows the driver to control and to monitor the charging process of an EV conveniently and, moreover, it can provide the driver with vehicle information stored in the EVSE management server.