• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.138-144
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• 2006

In this paper, dual mode FET mixer for WiBro and wireless LAN(WLAN) applications has been designed in the form of dual gate FET mixer by using the cascode structure of two single gate pHEMTs. The designed dual gate mixer has been optimized to have variable conversion gain for WiBro and WLAN applications in order to save dc power consumption. The LO to RF isolation of the designed mixer is more than 20dB from 2.3GHz to 2.5GHz band. With the LO power of 0dBm and RF power of -50dBm, the mixer shows 15dB conversion gain. When RF power increases from -50dBm to -20dBm, the conversion gain decreases to -2dB from 15dB with bias change. The variable conversion gain has several advantages. It can reduce the high dynamic range requirement of AGC burden at IF stage. Also, it can save the dc power dissipation of mixer up to 90%.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.141-147
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• 2016

NHPP software reliability models for failure analysis can have, in the literature, exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, infinite failures NHPP models that repairing software failure point in time reflects the situation, was presented for comparing property. Commonly used in the field of software reliability based on Flexible Weibull extension distribution software reliability of infinite failures was presented for comparison problem. The result is that a relatively small shaping parameter was effectively. The parameters estimation using maximum likelihood estimation was conducted and model selection was performed using the mean square error and the coefficient of determination.. In this research, software developers to identify software failure property follows shape parameter, some extent be able to help is considered.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.3
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• pp.465-470
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• 2017

This paper designs and implements a smart garden system using probabilistic filter algorithm using SLAM that can be used in apartment or veranda. To do this, we used Arduino and environtal sensors, which are open hardware controllers, and designed to control and observe automatic water supply, lighting, and growth monitoring with three wireless systems (Bluetooth, Ethernet, WiFi). This system has been developed to make it possible to use it in an indoor space such as an apartment, rather than a large-scale cultivation system such as a conventional plant factory which has already been widely used. The developed system collects environmental data by using soil sensor, illuminance sensor, humidity sensor and temperature sensor as well as control through smartphone app, analyzes the collected data, and controls water pump, LED lamp, air ventilation fan and so on. As a wireless remote control method, we implemented Bluetooth, Ethernet and WiFi. Finally, it is designed for users to enable remote control and monitoring when the user is not in the house.

• Journal of Broadcast Engineering
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• v.22 no.4
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• pp.473-483
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• 2017

Since the advent of 3D and UHD contents, demand for high-quality panoramic images has been increasing. The UWV(Ultra-Wide Viewing) service uses a wider viewing angle than conventional panoramas to provide a lively experience for users and enhance their understanding of the event. In this paper, we propose a spatial adjacency map generation method and an UWV file storage format technology to provide UWV service. The spatial adjacency map measures the similarity between images and generate the position information of the images based on similarity. And the stitching time of the image can be shortened through the generated position information. Through the spatial adjacency map, we generate the large screen content quickly. The UWV file format which is based on ISOBMFF process spatial adjacency map and videos and support random access. In this paper, we design the UWV player to verify the spatial adjacency map and UWV file format and show the result of experiments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.125-133
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• 2017

A parking structure has been on the spotlight to solve the parking problem in downtown area. However, the overall height of parking structure is stipulated less than 8m. Therefore, in this research, the flexural and shear capacity of 'wide composite beam' which can reduce story height and have long span, is evaluated. Based on test result, the rebar in truss did not affect its flexural strength. However, in the case of the specimen without the rebar, the mechanical bond strength decreased due to slip occurrence at 70% of the flexural yield strength. Based on the test of shear-bond behavior, all specimen without shear connector should be reinforced with 2 or more flat bar, because it did not have enough shear bond strength resisted by the mechanical bond mechanism.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.227-234
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• 2008

The development of wireless network technology allows high data rate seamless communication irrespective of the place and time in various emerging mobile service environment. Unlike wired networks, however, wireless networks utilize expensive limited bandwidth. MBS(Multicast Broadcast Service), which is supported by mobile WiMAX system based on IEEE802.16e, overcomes this problem using a shared downlink channel for efficiently supporting a number of users. However. the coverage and throughput of the system are significantly affected by the channel condition. In this paper we propose on MBS system employing Mobile Multi-Hop Relay(MMR) and adaptive modulation and coding(AMC) scheme. The result of NS-2 computer simulation shows that the throughput and transmission time are substantially improved by the proposed approach compared to the existing MBS system.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.33-38
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• 2016

As a communications system and using the wireless devices is increased at the world, the interference among devices at 2.4GHz band become issue. New complex content technology as education, concert, broadcast, thema-park are developed between Virtual Reality technology and tradition. That is expect an annual growth rate of more than 14%. Almost Virtual Reality devices use motion sense or a wireless joystick. Therefore it is necessarily to analyze the coexistence between Virtual Reality devices and Wi-Fi in the ISM band. The interference scenario and propagation of the Extended Hata Model was established to analyze the interference from WLAN into Virtual Reality devices. Through simulation results based on Monte-Carlo principle, separation frequency was obtained to protect WLAN interference from Virtual Reality devices.

• Journal of the Korean Data and Information Science Society
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• v.26 no.1
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• pp.11-19
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• 2015

A certain number of products are transported to be sold each month and some of them are returned for repair. In this study we first assume that the transported products are the ones that have been sold, Then nonparametric approach is applied to the warranty returns data to see how the reliability decreases over time. Parametric approach such as Weibull distribution is applied to the same data and the results for both nonparametric and parametric approaches are compared. Next we assume that there is a time lag between shipment and sale. Then both nonparametric and parametric approaches are applied to the time-lag data and the results are compared.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.5
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• pp.339-344
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• 2015

NHPP software reliability models for failure analysis can have, in the literature, exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, infinite failures NHPP models that repairing software failure point in time reflects the situation, was presented for comparing property. Commonly used in the field of software reliability based on Weibull extension distribution software reliability of infinite failures was presented for comparison problem. The result is that a relatively large shape parameter was effectively. The parameters estimation using maximum likelihood estimation was conducted and Model selection was performed using the mean square error and the coefficient of determination. In this research, software developers to identify software failure property follows shape parameter, some extent be able to help is considered.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.23-28
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• 2016

In this paper, we proposed the novel algorithm which controls the resolution of the HDMI(High Definition Multimedia Interface) by the channel estimation from WiFi-AP(Access Point) in the ISM(Industry-Science-Medical) band. The 2.4 and 5 GHz channel models are widely used since they have identical RF property as RSSI(Received Signal Strength Indication). Especially, the performance degradation of signal-transmission and streaming of WiFi will be occurred by the co-channel interference between AP(Access Point) and increased number of smart devices. Therefore, the optimization scheme of video format timing was designed by HDMI-CEC(Consumer Electronics Control) which considers the transmission speed of radio channel. The HDMI resolution, video quality of home-gateway and digital TV and the decision of PIP position can be maintained by the protocols between smart devices and DLNA(Digital Living Network Alliance) via proposed technique.