• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.461-475
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• 2006

In this paper, it is described about the tri-band mobile antenna system design to provide broadband multimedia and direct broadcasting services using goo-stationary Koreasat 3, simultaneously operated in Ka/K/Ku band. The radiating part of the antenna system with a fan beam characteristic in the elevation plane is composed of the quasi-offset dual shaped reflector and the tri-band feeder. The tri-band feeder is also composed of the Ka/K dual band feeder with the protruding dielectric rod, the circular polarizer, the ortho-mode transducer and the circular-polarized Ku band feed array. Especially, the Ka/K dual band circular polarizer was realized firstly using the comb-type structure. For fast satellite-tracking on the movement, the Ku band feed array has the structure of the $2{\times}2$ active phased array which can make electrical beams. And, the circular-polarized characteristic in the feed array was improved by $90^{\circ}$ rotating arrangement of four radiating elements polarized circularly by a $90^{\circ}$ hybrid coupler, respectively. Four beam forming channels to make electrical beams at Ku band are divided into the main beam channel and the tracking beam channel in the output, and noise temperature characteristics of each channel were analyzed on the basis of the contributions of internal sub_units. From the fabricated antenna system, the output power at $P_{1dBc}$ of Ka_Tx channel was measured more than 34.1 dBm and the measured noise figures of K/Ku_Rx channels were less than 2.4 dB and 1.5 dB, respectively, over the operating band. The radiation patterns with co- and cross-polarization in the tri-band were measured using a near-field measurement in the anechoic chamber. Especially, Ku radiation patterns were measured after correcting each initial phase of active channels with partial radiation patterns obtained from the independent excitation of each channel. The antenna gains measured in Ka/K/Ku band of the antenna system were more than 39.6 dBi, 37.5 dBi, 29.6 dBi, respectively. And, the antenna system showed good system performances such as Ka_Tx EIRP more than 43.7 dBW and K/Ku_Rx G/T more than 13.2 dB/K and 7.12 dB/K, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.9-14
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• 2020

In this paper, Qualification Model of frequency synthesizer is designed for X-band SAR system and performed electrical and environment test. Designed frequency synthesizer generate 13.65 GHz with very low phase noise performance. The integrated phase noise from 10Hz to 1MHz is -37.91 dBc. IRF performances are analyzed according to phase noise and jitter. Also, thermal and structure analysis are achieved for stable operation in space environment. Designed frequency synthesizer is consist of 2 modules of 6U size and generate L-band, C-band, Ku-band. The result of this study would enhance the design ability of RF module and help the frequency synthesizer design for SAR payload system.

• The KIPS Transactions:PartD
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• v.18D no.3
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• pp.197-204
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• 2011

Set-top Box which receives broadcasting signal and delivers it to display device such as TV usually doesn't have low-power mode, standby power mode. On the other side, most consumer electronics support standby power mode. The main reasons come from technical barriers and operational stability. Set-top box normally consumes 80~90% power of active mode even though turning off. This is much higher compared to other consumer electronics which consume less than 1W in standby power mode. However, most developed countries including Korea are enforcing the regulations which enhance energy efficiency of set-top box. This paper describes design and development of low-power set-top box. Key technologies are SoC supporting low-power mode, system hardware and software operating in separated power mode, and middleware managing the power with broadcasting system. Finally, we show energy saving expectation through development and proliferation.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.755-764
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• 2019

Currently commercially available light field cameras are difficult to acquire 5D light field video since it can only acquire the still images or high price of the device. In order to solve these problems, we propose a deep learning based method for synthesizing the light field video from monocular video. To solve the problem of obtaining the light field video training data, we use UnrealCV to acquire synthetic light field data by realistic rendering of 3D graphic scene and use it for training. The proposed deep running framework synthesizes the light field video with each sub-aperture image (SAI) of $9{\times}9$ from the input monocular video. The proposed network consists of a network for predicting the appearance flow from the input image converted to the luminance image, and a network for predicting the optical flow between the adjacent light field video frames obtained from the appearance flow.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.149-155
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• 2019

In this paper, phase shifter has been designed and manufactured to apply to passive phase array seeker for Ka-band and its performance was confirmed. It was designed as a key element for conducting electric beam steering by adjusting the phase of the array element. Insertion loss of less than 1.5dB and phase accuracy of less than $10^{\circ}$(RMS) in operation bandwidth of 1GHz were checked. The performance identified by the actual fabrication was further analyzed by applying the beam pattern analysis based on the array synthesis theory. The effect of the final performamnce of the proven phase shifter on the performance and pointing error and angular accuracy of the passive phase array antenna beam pattern was analyzed. Then, the validation of the proposed phase shifter has been made.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.35-42
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• 2021

The research of amplifier have been actively conducted to replace the Traveling Wave Tube Amplifier (TWTA) in the mmWave. For Solid State Power Amplifiers (SSPA), which combine semiconductor-type devices to obtain high output, Low-loss, high-efficiency combination techniques are required to meet the required output as the output of a single relatively low device is relatively low. In this paper, we design and produce an 8-way waveguide combiner and a reflective loss of more than 20dB and a binding efficiency of 85% or more were identified. Field analysis calculates the critical power inside the combiner. It secured stable Power Ratings and built-in coupler for power monitoring to achieve miniaturization and light weight.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.35-42
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• 2022

In this paper, a method to increase the combining efficiency and isolation of the combiner, the core module of SSPA (solid state amplifier), was studied. Specifically, the isolation was secured by matching the common port and the isolation port in the waveguide combiner. The matching structure for matching is in the form of a circular disk and is engraved inside the waveguide combiner. The structure is very simple, so it is possible to secure stable performance. And this structure showed more than 60 times higher critical power performance compared to previous studies, confirming that it is suitable for high output. And by combining 1-stage T-junction and 2, 3 stage MagicT combiner, miniaturization was achieved and the combining efficiency was optimized by reducing the insertion loss. The fabricated waveguide coupler obtained an isolation of 16dB or more and a coupling efficiency of 86.2%.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.51-59
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• 2003

Marine Casualty Forecasting System (MCFS) is to broadcast the prediction number and risk level of marine casualties as like daily weather forecasting. The MCFS consists of marine casualty numerical D/B, prediction model and, three-dimensional statistics visualization system. The implementation procedure for the numerical D/B is described in the paper. The data relating to a total of 724 ship casualties in the west-southern sea area (latitude 33$^{\circ}$N∼35$^{\circ}$ and longitude 124$^{\circ}$E∼127$^{\circ}$E) of Korean peninsula for 11 years (1999∼2000) have been compiled. The analysis method of numerical D/B is proposed and discussed its usability.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1310-1318
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• 2007

First of all, What was the modeling technique used to model 3D-Game character? It's a technique developed along several years, by experience... here is the bases Low polygons characters I always work in low polygon for two reasons -You can easily modify a low-poly character, change shapes, make morph for facial expressions etc -You can easily animate a low-poly character When the modeling is finished, Second, In these days, Computer hardware technologies have been bring about that expansion of various 3D digital motion pictured information and development. 3D digital techniques can be used to be diversity in Animation, Virtual-Reality, Movie, Advertisement, Game and so on. Besides, as computing power has been better and higher, the development of 3D Animations and Character are required gradually. In order to satisfy the requirement, Research about how to make 3D Game modeling that represents Character's emotions, sensibilities, is beginning to set its appearance. 3D characters in 3D Games are the core for the communications of emotion and the informations through their facial expression and characteristic motions, Sounds to Users. All concerning about 3D motion and facial expression are getting higher with extension of frequency in use. Therefore, in this study we suggest the effective method of modeling for 3D character and which are based on 2D Graphics.

• Journal of Broadcast Engineering
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• v.19 no.5
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• pp.616-626
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• 2014

In this paper, we introduce a real-time stereo-to-multiview conversion system using FPGA and GPU. The system is based on two different devices so that it consists of two major blocks. The first block is a disparity estimation block that is implemented on FPGA. In this block, each disparity map of stereoscopic video is estimated by DP(dynamic programming)-based stereo matching. And then the estimated disparity maps are refined by post-processing. The refined disparity map is transferred to the GPU device through USB 3.0 and PCI-express interfaces. Stereoscopic video is also transferred to the GPU device. These data are used to render arbitrary number of virtual views in next block. In the second block, disparity-based view interpolation is performed to generate virtual multi-view video. As a final step, all generated views have to be re-arranged into a single image at full resolution for presenting on the target autostereoscopic 3D display. All these steps of the second block are performed in parallel on the GPU device.