• Journal of Broadcast Engineering
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• v.18 no.1
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• pp.88-97
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• 2013

Collaborative filtering(CF) for the personalized recommendation is a successful and popular method in recommender systems. But the mainly researched and implemented cases focus on dealing with independent items with explicit feedback by users. For the domain of TV program recommendation in VOD service platform, we need to consider the unique characteristic and constraints of the domain. In this paper, we studied on the way to convert the viewing history of each TV program episodes to the TV program preference by considering the series structure of TV program. The former is implicit for personalized preference, but the latter tells quite explicitly about the persistent preference. Collaborative filtering is done by the unit of series while data gathering and final recommendation is done by the unit of episodes. As a result, we modified CF to make it more suitable for the domain of TV program VOD recommendation. Our experimental study shows that it is more precise in performance, yet more compact in calculation compared to the plain CF approaches. It can be combined with other existing CF techniques as an algorithm module.

• Journal of Broadcast Engineering
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• v.23 no.5
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• pp.656-668
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• 2018

VR (Virtual Reality) is one of the important research topics in the field of multimedia application system. The quality of the visual data composed from multiple pictures depends on the performance of stitching technique. The stitching module consists of feature extraction, mapping of those, warping, seam finding, and blending. In this paper, we proposed a preprocessing scheme to provide the efficient mask for seam finder. Incorporating of the proposed mask removes the distortion, such as ghost and blurring, in the stitched image. The simulation results show that the proposed algorithm outperforms other conventional techniques in the respect of the subjective quality and the computational complexity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.690-695
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• 2014

In this paper, we develop a explosion-proof LED lighting (Ex circuit) circuit of Explosion-proof LED Signal Lamp (Ex LSL) to utilize the core module of the explosion-proof Local Control System (Ex LCS) for offshore plant applications. And then analyzed its electrical, optical and thermal characteristics. Ex circuit was applied input voltage from AC/DC(12~254) V. In this experiments, stable light-on characteristics were confirmed by eyes for the every input voltages with min. 78,462 and max. $517,975cd/m^2$ of luminance. also Output current and output luminance was made proportional. Because the measured maximum surface temperature of Ex circuit was $54.23^{\circ}C$ at AC 48 V, Ex circuit was rated with T6 of temperature class. Finally, Ex circuit was shown stable light on characteristics under the $-50^{\circ}C$ and $60^{\circ}C$ during 12 hours of test period.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.425-430
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• 2013

Robust and high speed underwater communication is severely limited when compared to communications in terrestial. In free space, RF communication operates over long distances at high data rates. However, the obstacle in seawater is the severe attenuation due to the conducting nature. Acoustic modems are capable of long range communication up to several tens of kilometers, but it has low data-rate, high power consumption and low propagation speed. An alternative means of underwater communication is based on optics, wherein high data rates are possible. In this paper, the characteristics of underwater channel in the range of visible wavelength is investigated. And the possibility of optical wireless communication in underwater is also described. The LED-based transceiver and CMOS sensor module are integrated in the system, and the performance of image transmission was demonstrated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.150-159
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• 2015

An experimental study on frequency characteristics of the microphone array covered with Kevlar sheet was conducted in the closed test section. Microphones that were flush-mounted in the wall of wind tunnel were subjected to very high flow noise resulting from the turbulence in the wall boundary layer. This noise interference by the boundary layer was referred as 'a microphone self-noise' and various approaches were studied to reduce this interference. Recessed microphone array with high tensioned cover was one of the good approaches to reduce this self-noise. But, the array cover could cause an unexpected interference to the measuring results. In this paper the frequency characteristics of the microphone array with Kevlar cover was experimentally studied. The white noise was used as a reference noise source. Three kinds of tensions for the Kevlar cover were tested and those results were compared with the test results without the Kevlar cover. The gap effect between the cover and microphone head was also tested to find out the proper position of microphone in the array module. Test results show that the mid-tension and 10mm gap was the best choice in the tested cases.

• Journal of Society of Preventive Korean Medicine
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• v.19 no.2
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• pp.159-167
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• 2015

Objective : Recently many kinds of food therapies have sprung up to prevent or manage disease and to promote health. Seeing Korean history, the Korean medical doctors have been applying food therapy based on the thought that the dietary sources were as important as the medicine. Therefore, in this study, we designed a mobile edutainment game prototype with the goal of providing education about healthy food knowledge for users who belongs to different constitutional types. Materials and Method : We adopted the Sasang Constitutional Medicine as the medical background knowledge for our edutainment game design. Based on the user study, we developed the process of edutainment system which is composed of 'My game', 'My constitution', and 'My food'. Among the whole process, we developed a prototype for the core module - the 'My game' part. This prototype used a jumping game for mobile devices that is composed of training, level 1 and level 2 stages. Results : From the target user evaluation, it was proved that 1) in terms of the learning effect of healthy diet, the edutainment game we developed has a significant advantage over the conventional learning media. 2) after playing the edutainment game, the good and bad food identification accuracy based on picture and text format were increased by 44% and 42% respectively, and 3) target users perceived enjoyment while using this prototype, as well as showed positive intention to use this game as edutainment tool in the future. Conclusion : We designed and developed mobile edutainment game prototype to educate healthy food knowledge based on Sasang Constitutional Medicine. Through user evaluation, we proved that our prototype enhanced healthy food knowledge and that user accepted the prototype as a beneficial edutainment tool.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.2
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• pp.83-95
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• 2020

The water circulation in agricultural watersheds changes with the operation of agricultural reservoirs, it is necessary to classify and evaluate them into upstream, agricultural reservoirs, irrigation districts, and downstream. Therefore, in this study, we developed the agricultural water circulation rate (AWCR) considering an agricultural reservoir and irrigation district by improving the water circulation rate of the Water environmental conservation Act. we applied it to Jinwi watershed using the module-based hydrologic analysis system to simulate the water circulation for agricultural reservoirs and irrigation areas. The model performance during the validation period was NSE of 0.762 for the downstream stream and 0.682 for the reservoir level. And the hydrograph separation model was applied to separate the direct and baseflow. As a result of this study, The AWCR of Jinwi watershed was 71.8% on average, which was higher than the water circulation rate estimated by the downstream hydrograph separation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.115-120
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• 2005

This paper describes the design and implementation of engineering model(EM) of Mass Memory Unit(MMU) for Science and Technology Satellite 2(STSAT-2) and the results of integration test. The use of Field-Programmable Gate Array(FPGA) instead of using private electric parts makes a miniaturization and lightweight of MMU possible. 2Gbits Synchronous Dynamic Random Access Memory(SDRAM) module for mass memory is used to store payload and satellite status data. Moreover, file system is applied to manage them easily in the ground station. RS(207,187) code improves the tolerance with respect to Single Event Upset(SEU) induced in SDRAM. The simulator is manufactured to verify receiving performance of payload data.

• Journal of Biomedical Engineering Research
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• v.31 no.5
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• pp.395-400
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• 2010

Hypertension is the chronic disease that the 16% of total population are suffering, and it needs to be studied to find alternative treatment because of the tolerance and side effect of medications that may bother some patients. in this paper, we verified practicality of implantable electrical stimulator that can readily change stimulus magnitude and frequency. And this device is possible to stimulate baroreflex or parasympathetic nerve. Therefore we performed in vitro tests and animal experiment for device's operating conditions. This device consist of implantable electrical stimulator and extracorporeal control/monitoring system. Stimulator was designed to make 1Hz~100Hz pulses and it can change continuous or periodic pulse train type. And this device can control stimulator's function and monitor stimulator's status and patients' blood pressure at exterior of body using ZigBee module as wireless telecommunication. We verified that stimulator have error rate under 5% at 50mm depth of organs and, stimulator makes high-efficiency energy with closer position of two electrodes. Also we can confirm the performance of device that decreasing blood pressure and heart rate of a rat by electrical stimulation.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.29-33
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• 2018

Accident likelihood is growing due to a correlation for gas and electricity installed in the area of dense energy consumption like traditional market and underground shopping center. In order to prevent and respond accident risks related to gas and electricity in this area, it should be monitored and predicted for factors of gas leak or electricity by developing safety management system. This study is about accident prediction model development considering fire risk factor related to gas accident. The temperature variation characteristic near a gas burner was analyzed. Also, accident prediction algorithm and related module were developed to prevent fire in the area of dense energy consumption.