• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.427-435
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• 2018

Many countries are trying to deploy satellite surveillance systems for their national defense, and one of these system uses optical systems to observe the satellites above their territories. The optical satellite surveillance system requires the coordinates of the satellites in an acquired image and expects that those coordinates to be delivered to the tracking system. The proposed method detects the satellite sources in a high-resolution image with fast image processing for the optical surveillance system. To achieve faster detection, the proposed method reduces the size of the original image and approximates the trajectory of a satellite, so image processing methods are only applied to the nearby area of the approximated trajectory in the original image. The proposed method shows the similar detection performance faster than the previous method.

• Journal of Broadcast Engineering
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• v.25 no.1
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• pp.109-112
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• 2020

VVC uses 67 modes in intra prediction. Most probable mode (MPM) is used to reduce data for the representation of intra prediction mode. If the mode to send exists in the MPM candidate, the index of the MPM list is transmitted. If it does not exist in the MPM candidate, TBC encoding is applied. When TBC is applied in intra prediction, three are selected in order of low number mode and coded into 5 bits. The remaining modes except the mode encoded by 5 bits are encoded by 6 bits. In this paper, we examine the limitations of the TBC used in VVC intra prediction and propose an adaptive method that can encode more efficiently than conventional methods when using TBC in intra prediction. As a result, the coding efficiency of the overall coding performance is 0.01% and 0.04% in AI and RA, respectively, compared with the conventional coding method.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.249-260
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• 2013

Recently, High-Efficiency Video Coding (HEVC) has been developed as a new video coding standard mainly focusing on the coding of ultra high definition (UHD) videos as the high resolution and high quality videos are getting more popular. Furthermore, the scalable extension of HEVC is being standardized for more efficient provision of HD and UHD services in the communications-broadcasting convergence environment. In this paper, we propose an improved scalable video coding method of H.264/AVC to achieve high coding efficiency particularly for UHD and HD videos. The basic idea is to allow large block size in H.264/AVC SVC, which results in more efficient inter-layer prediction and syntax elements coding. The experimental results show that it achieves an average 4.53% reduction in BD-rate relative to H.264/AVC SVC.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.629-634
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• 2016

This paper describes the implementation of a ZigBee sensor node that can be utilized as a multiband and machine to machine (M2M) communication gateway. The IEEE 802.15.4-2003 standard was used as the wireless network frequency band. Ember's Type EM357 SoC was used as the transmission and reception device to perform the communication function, and it was also used for both the main M2M gateway and the sensor node. For the implementation of the operating protocol, EmberZNet Stack 4.5.4 from the Ember Corporation was used. The measurement of the reception sensitivity in the receiving module and the actual output signal from the reference were obtained from the transmission of a packet, and the packet included the M2M gateway within the attached ZigBee sensor. The packet error rate was measured as 0% with a -98 dBm reception sensitivity at the ZigBee frequency. In addition, excellent current characteristics of the ZigBee modules were shown by the implementation of the low-power circuit.

• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.2
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• pp.23-29
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• 2010

In this study, there is a modeling for the procedure and operational method of the project based capstone design and related products which are a certificate of graduate status, and those results were evaluated by self-review and the performance assessment. Finally, the improvements in the operating management method are proposed. Before one semester by the end of to the assessment, the design thesises of capstone results are fixed to the 15 sets by 2 people in each group. All teams are satisfied the criteria of evaluation, and they all got a grad over 60 points. The mean value of their's score are similar to the average of recent 5 years. The results of self-evaluations and questionaries indicate a totally self-satisfied(3.8~4points out of 5), but the weak parts of this procedure are known as the area of plan making and Implementation. Also, there are some problems associated with a group of people into a team by the human relation rather than knowledge based mutual supplementation.

• Journal of Practical Engineering Education
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• v.6 no.1
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• pp.23-29
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• 2014

In this study, there is a modeling for the procedure and operational method of the project based capstone design and related products which are a certificate of graduate qualification, and those results were evaluated by self-review and the performance assessment. Processing of research based on wireless searching robot is described according to the model. Before one semester by the end of to the assessment, the design thesis of capstone results was fixed to 18 groups with two people in each group. 13 teams out of 18 teams are satisfied the criteria of evaluation, and they all got a grade over 60 points and the other teams are not qualified at the first stage of final judgment. The total team mean average is 71.79. The research based on wireless searching robot was earned the highest average point among the other teams which is 96.1.

• KIEAE Journal
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• v.16 no.5
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• pp.65-71
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• 2016

Purpose : The solar shading device carries out roles in a reduction of the cooling load and an improvement of the thermal comfort of occupants by adjusting incident solar radiation. In addition, The shading device enhances the visual sensation comfort by controlling the optical properties. In order to improve building performance and comfort of occupancy, interests in application of the shading devices are getting increasing. This study investigated the application and effectiveness of the external shading device design using statistical analysis. The outcome of this paper could be utilized for the realization of status quo and for an estimation of effectiveness of the shading device Method : The period of data gathering was between 2003 and 2014 and total 459 cases of practical building project were investigated. Firstly, this study defined qualification of the shading devices; the shading device should have minimum protruding lengths of 150mm to outside and have the function of shading control. This paper investigated application rate of the shading device in real project, regional rate of application, annual change of application, materials and types. Result : The statistical analysis showed that the application rate of shading devices was 25.7% in total 459 building design projects. The application rate in central and southern region was 25.3% and 27.0% respectively. Meanwhile, Jeju region showed 22.2%, which was the lowest rate although this area needs more shading devices. The application number of the shading device was the smallest in 2007, but the rate gradually increased after that. The applications was the largest in 2014 due to growing interest of the shading devices in the building.

• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.36-40
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• 2003

Freezing of water in a polymer electrolyte membrane fuel cell (PEMFC) may cause severe problems in driving a fuel cell vehicle during the winter time. Characteristics of PEMFC which suffered low temperatures below zero degree was examined with the thermal cycles from 80 to $-10^{\circ}C$. With the thermal cycles, the cell performance was degraded due to the phase transformation and volume changes of water. Effects of freezing of water in PEMFC on the electrode structure and polarization resistance were examined by BET analysis, cyclic voltammetry, and AC impedance spectroscopy.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.166-174
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• 2014

Fuel injection pressure has steadily increased in diesel engines for the purpose of improving fuel efficiency and cleaning exhaust gas, but it has now reached a point, where the cost for higher pressure does not warrant additional gains. Common rail systems on modern diesel engines have fuel pumps that are mechanically driven by crankshaft. The pumps actually house two pumping module inside: a low pressure pump component and a high pressure pump component. Part of the fuel compressed by the low pressure component returns to the tank in the process of maintaining the pressure in the common rail. Since the returning fuel represents pumping loss, fuel economy improves if the returned fuel can be eliminated by using a properly controled electrical fuel pump. As the first step in developing an electrical fuel pump the fuel supply system on a 6 liter diesel engine was modeled with AMESim to analyze the workload and the fuel feed rate of the injection pump, and the results served as basis for selecting a suitable servo motor and a reducer to drive the pump. A motor controller was built using a DSP and a program which controls the common rail pressure using a proportional control method based on the target fuel pressure information from the engine ECU. A test rig to evaluate performance of the fuel pump is implemented and used to show that the newly developed electrically driven fuel pump can satisfy the fuel flow demand of the engine under various operating conditions when the rotational speed of the pump is adequately controlled.

• Journal of Energy Engineering
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• v.16 no.3
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• pp.149-154
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• 2007

An experimental study on the air-side pressure drop of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side pressure drop in the literature is not based on a consistent approach. This paper focuses on method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry and wet surface pressure drop estimation in fin-tube heat exchanger. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the air-side pressure drop on design conditions of condenser and evaporator. Results are pre-sented as plots of friction f-factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of $150{\sim}250\;kg/m^2s$ with air flows at velocity ranges from 0.38 m/s to 1.6 m/s.