• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.1012-1019
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• 2015

This paper shows the acceleration of iterative physical optics(IPO) for radar cross section(RCS) by using two techniques effectively. For the analysis of the multiple reflection in the cavity, IPO uses the near field method, unlike shooting and bouncing rays method which uses the geometric optics(GO). However, it is still far slower than physical optics(PO) and it is needed to accelerate the speed of IPO for practical purpose. In order to address this problem, graphic processing unit(GPU) can be applied to reduce calculation time and adaptive iterative physical optics-change rate(AIPO-CR) method is also applicable effectively to optimize iteration for acceleration of calculation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1765-1772
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• 2015

In the underwater acoustic communication channels, multipath reflection become the cause of obstacle. Generally, equalizer has been applied to overcome these problems. In this paper, the method was proposed to optimize tap-length of decision feedback equalizer using genetic algorithm. After inputting feed-forward filter length and feed-back filter length as genetic information of the genetic algorithm, it optimize tap-length using BER(bit error rate) calculation in accordance with object function. The object function consist of decision feedback equalizer and BER calculation. For the purpose of BER calculation in the object function, the method was proposed to optimize the tap-length of decision feedback equalizer with genetic algorithm using preamble signals. As a result of experiments, the optimized BER is 0.0355 for signals which were received through a 25m receiver and which were applied to calculate BER merely using preamble signals in object function. When all data were used to calculate BER in object function, the optimized BER is 0.0215.

• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.487-492
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• 2013

Underwater acoustic communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Among the iterative coding scheme, turbo codes, LDPC codes and convolutional code based on BCJR algorithm are dominant channel coding schemes in recent. Therefore this paper analyzed the performance of iterative codes based on turbo equalizer with the same coding rate and similar codeword length. The performances of three kinds of iterative codes were evaluated in the environment of underwater acoustic communication channel that are real data collected in Korean east sea. The distance of transmitter and receiver was 5Km and data rate was 1Kbps. As a result, convolutional code based on BCJR algorithm has better performance in underwater channel than turbo codes and LDPC codes.

• Journal of the Semiconductor & Display Technology
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• v.13 no.3
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• pp.27-33
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• 2014

To develop high efficiency crystalline solar cells, the $SiN_x$ film for surface passivation and anti-reflection coating is very important and it is generally deposited by PECVD. In this paper, the $SiN_x$ film deposited by Hot-Wire chemical vapor deposition(HWCVD) that has no plasma damage was studied. First, to optimize the $SiN_x$ film deposition process, $SiH_4$ gas rate and substrate temperature were varied and then refractive index and thickness were measured. When $SiH_4$ gas rate was 22sccm and substrate temperature was $100^{\circ}C$, refractive index was 1.94 and higher than that of other process conditions. Second, the lifetime was measured by varying the annealing temperature and time. The annealing process was made from 5 to 30 minutes at $300{\sim}500^{\circ}C$. When the annealing temperature was $100^{\circ}C$ and time was 10minute, the lifetime was the highest. The lifetime of annealed samples was also measured after the firing process at $975^{\circ}C$. Although the lifetime of all samples was decreased by firing process, the lifetime of annealed samples before the firing process was higher than that of fired samples only. Finally, the characteristics of solar cells with HWCVD $SiN_x$ film were measured.

• Journal of The Korea Institute of Healthcare Architecture
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• v.14 no.1
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• pp.31-38
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• 2008

Nursing Homes are different from other medical facilities, because they have a living space. And most of residents in a nursing home have dementia, therefore nursing homes are in control of outdoor activities for resident's safety and most of residents live in the living room at the daytime. The purpose of this study is analysis of spacial behaviors of residents in the living room, and reflection of the analysis into the architectural plan of nursing homes.There are two activities, individual activity and social interchange activity, in a living room and the role of a living room is semi-private space that includes both of them. Most numerous activities are watching TV and take a eat. Activities are different in accordance with the position at the living room. Individual activity and social interchange activity is same ratio in the middle and the ratio of social interchange activities are more than individuals in outside of living room. but alcove use of private.The types of living rooms are distinguished by combination of functions of livingroom, activity-room, and diningroom. The activity of use of residents have been shown different phases following the types of livingroom. The type of combination has been seen high rate of use and private activities and social communications are expressed evenly. The type of mixing has been seen low rae of use, but two activities, the above, are equal. The type of separation has been seen not only low rate of use, but also there has been only private activities.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.967-974
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• 2017

In this paper, a differential-braking-based yaw moment control system was developed to guarantee robust performance against road bank angle. A new target yaw rate model was established by combining the signal from a lateral acceleration sensor and 2-DOF single track model. In addition, a disturbance observer was utilized to take into account parameter uncertainties in yaw dynamics and to improve robust performance of the controller. CARSIM, which is a multi-DOF vehicle dynamic simulation tool, was used to verify the performance of the proposed controller in various driving scenarios. The simulation results indicate that the stability of the vehicle was robustly maintained by the controller, which is characterized by the reflection of the signal of a lateral acceleration sensor signal and by the compensation of the errors in the model parameters via the disturbance observer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.65-65
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• 2007

Microstructure and surface roughness of the sensing materials should be improved to use them in advanced sensor applications because the uneven surface roughness degrades the light reflection, pattern resolution, and devices performance. Chemical mechanical polishing (CMP) processing was selected for improving the surface roughness of $CeO_2$ which is one of the well known materials for the oxygen gas sensors. Surface roughness and removal rate of spin coated $CeO_2$ thin films were examined with a change of CMP process parameters such as down force and table speed. The optimized process condition, reflected by the surface roughness with the hillock-free surface as well as the excellent removal rate with the good uniformity, was obtained. The effects of the improved surface roughness on the sensing property of $CeO_2$ thin films were also confirmed. The improved sensitivity of $CeO_2$ thin films for oxygen sensors were obtained after CMP process by the improved surface characteristics. Therefore, we conclude that sensing property of $CeO_2$ thin film is strongly dependent on the surface roughness of $CeO_2$ thin films by using CMP process.

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.262-267
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• 2018

In this paper, we designed a new antireflective film to improve the optical efficiency of organic light-emitting diode displays (OLEDs). The reflection characteristics in the normal and side viewing directions of OLEDs with the antireflective film were calculated, depending on the degree of polarization and transmittance of the currently used polarizer when used in the antireflective film of an OLED. The results showed that when the polarization degree of the commercial polarizer (99.990~99.995%) is lowered to 99.900%, the average reflectance of the antireflective film is increased by about 0.1% (2.5% in terms of rate of increase) which is difficult to notice with the human eye, while the transmittance is increased by 1.63~3.34% (4.2~8.2% in terms of rate of increase). This study provides an optimal design for high-light-efficiency OLEDs with good antireflection properties.

• Journal of The Korean Association of Information Education
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• v.26 no.5
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• pp.327-340
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• 2022

This study applied effective playful learning to increase the learning motivation of non-CS major students to help them achieve learning and to successfully operate online SW liberal arts classes for 560 students. As a result of analyzing the students' reflection journals, most of the students accepted the 'white radish' of dialect names as fun playful learning in the process of learning local variables and global variables. And they were surprised and amazed at discovering unexpected contents in our SW class. It was found that they experienced delight in learning, learning-flow, confidence, and intrinsic motivation. In the final term exam at the end of the semester, it was confirmed that the correct rate of 92% for questions related to local and global variables was higher than the average rate of other questions' correctness of 67.1%.

• Design Convergence Study
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• v.16 no.6
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• pp.153-167
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• 2017

Nowadays, as many robots are developed for desktop, users interact with the robots based on speech. However, due to technical limitations related to speech-based interaction, an alternative is needed. We designed this research to design a robot that interacts with the user by using unconditional reflection of biological signals. In order to apply bio-signals to robots more effectively, we evaluated the robots' overall service evaluation, perceived intelligence, appropriateness, trustworthy, and sociability according to the degree of the robot's embodiment level and the response speed of the robot. The result showed that in terms of intelligence and appropriateness, 3D robot with higher embodiment level was more positively evaluated than 2D robot with lower embodiment level. Also, the robot with faster response rate was evaluated more favorably in overall service evaluation, intelligence, appropriateness, trustworthy, and sociability than the robot with slower response rate. In addition, in service evaluation, trustworthy, and sociability, there were interaction effects according to the robot's embodiment level and the response speed.