• Journal of IKEEE
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• v.25 no.3
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• pp.578-583
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• 2021

This paper describes acceleration tests for reliability of semiconductors. It also describes AEC-Q100, international test standard for reliability of automotive semiconductors. Semiconductors can be used for dozens of years. So acceleration tests are essential to test potential problems over whole period of product where test time is minimized by applying intensive stresses. AEC-Q100 is a typical acceleration test in automotive semiconductors, and it is designed to find various failures in semiconductors and to analyze their causes of occurance. So it finds many problems in design and fabrication as well as it predicts lifetime and reliability of semiconductors. AEC-Q100 consists of 7 test groups such as accelerated environmental stress tests, accelerated lifetime simulation tests, package assembly integrity tests, die fabrication reliability tests, electrical verification tests, defect screening tests, and cavity package integrity tests. It has 4 grades from grade 0 to grade 3 based on operational temperature. AEC-Q101, Q102, Q103, Q104, and Q200 are applied to discrete semiconductors, optoelectronic semiconductors, sensors, multichip modules, and passive components, respectively.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.428-438
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• 2021

For long-range communication in deep water, low carrier frequency is efficient due to a decrease in transmission loss. However, there is a limitation in that the data rate decreases due to a narrow bandwith. In order to increase the data rate in an environment with a limited bandwidth, it is necessary to design a higher-order modulation scheme. This paper analyzes the long-range communication data modulated by higher-order modulation schemes. The long-range communication experiment (23 km ~) was conducted in East Sea in October 2020. During the experiment, a vertical line array was utilized and communication sequences were modulated by Phase Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM) schemes and transmitted by a towed source. In more detail, PSK modulation consists of quadrature PSK and 8PSK, QAM modulation consists of 8QAM and 16QAM. Time reversal processing is applied to mitigate inter-symbol interference by utilizing the correlation between received signals and channel impulse responses. All modulation schemes show successful results at 23 km range, demonstrating the feasibility of higher-order modulation in long-range communication.

• Journal of Korean Physical Therapy Science
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• v.28 no.2
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• pp.46-56
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• 2021

Purpose: The purpose of this study is to examine whether the level of participation in physical activity affects the mental health of adolescents, that is, their subjective well-being. In addition, we would like to see if adolescents can improve their satisfaction with life away from the negative emotions they are currently feeling through physical activities such as hand-help and consolation activities and check if self-esteem has mediating effects in this process. Design: Survey. Methods: The survey was conducted by the surveyor, with a total of 9,041. Results: First, it shows that the higher frequency of adolescents' physical activity leads to higher self-esteem and subjective well-being. Second, it shows that the higher the self-esteem leads to higher subjective well-being felt by adolescents. Third, the level of youth physical activity itself contributes to subjective well-being while also affecting self-esteem, and the self-esteem also affects the subjective well-being that adolescents perceive. Conclusion: It will be necessary to provide programs to enhance subjective well-being for students with poor school life adaptation and satisfaction with life, as well as continuous attention such as organization and counseling of programs in schools to enhance self-esteem. In addition, it is considered that by encouraging and guiding teenagers with low satisfaction with life and low self-esteem to physical activities such as volunteer activities and leisure activities that suit their aptitude, and the adolescents will get away from the negative emotions they are currently feeling and increase their satisfaction with adaptation to school life and life.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.439-445
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• 2020

In this paper, the seismic performance evaluation was performed on 100 existing open-cut power cable tunnels, including ones that did not consider seismic design, in order to verify that the government's demand level (seismic special grade, 0.22 g). The results of the seismic performance evaluation show that most of the tunnels have seismic performance of 0.3 to 1 g, satisfying the level of the seismic special grade and securing the seismic safety. Meanwhile, the earthquake response analysis and structural test were performed to verify the validity of the method and the results of the seismic performance evaluation of the tunnels by the response displacement method, and to verify their seismic safety. As a result, the relative displacement due to the response displacement method under the 0.22 g earthquake was conservative than the results of the earthquake response analysis, and the results of load-displacement curves and response modification coefficient calculation by real scale structural tests showed the safety of the tunnels.

• Journal of Convergence for Information Technology
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• v.11 no.4
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• pp.55-63
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• 2021

Recently, the incidence rate of malicious codes is over tens of thousands of cases, and it is known that it is almost impossible to detect/respond all of them. This study proposes a method for detecting multiple behavior patterns based on a graph database as a new method for dealing with malicious codes. Traditional dynamic analysis techniques and has applied a method to design and analyze graphs of representative associations malware pattern(process, PE, registry, etc.), another new graph model. As a result of the pattern verification, it was confirmed that the behavior of the basic malicious pattern was detected and the variant attack behavior(at least 5 steps), which was difficult to analyze in the past. In addition, as a result of the performance analysis, it was confirmed that the performance was improved by about 9.84 times or more compared to the relational database for complex patterns of 5 or more steps.

• Journal of the Korea Society of Computer and Information
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• v.26 no.11
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• pp.59-66
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• 2021

This study is to verify the effectiveness of initial planning verification using paper prototyping while methodologies are being developed to verify the direction of game planning in a short time at low cost since it is having a hard time to verify the direction and fun of the game by taking a lot of capital and time in the initial planning process as the game development becomes larger. It conducted paper prototyping production for about 40 students who are learning game planning for a semester, and trained them on how to motivate using core mechanical diagrams, scrums, and basic psychological needs that can effectively materialize the ideas of their early game planning. Through this curriculum, board games were completed with eleven paper prototyping, and it was confirmed that students who participated in the class were meaningful in verifying fun and securing gameability through cross-play.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.1-8
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• 2019

The electromagnetic forces generate a torque on the gimbal motor, and changes in the coil current causes torque ripple. This affects the gimbals' speed and results to unstable satellite attitude. It is therefore essential to reduce the torque ripple of the gimble motor with the aim of improving the attitude control accuracy of the satellite. This paper theoretically analyzes the torque generated from the modeling of a motor for general concentrated winding and distributed winding. The prototype was designed and fabricated through selection of the winding that reduces the torque ripple through simulation results. The results of the magnetic fields' theoretical analysis and the back electromotive force of the prototype were compared with the calibrated results for verification of conformity and manufacture of the design. The low-speed test proved that the torque ripple is reduced by improving the speed stability.

• Journal of Broadcast Engineering
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• v.24 no.4
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• pp.660-669
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• 2019

Recently, with the development of three-dimensional scanning devices and multi-dimensional array cameras, research is continuously conducted on techniques for handling three-dimensional data in application fields such as AR (Augmented Reality) / VR (Virtual Reality) and autonomous traveling. In particular, in the AR / VR field, content that expresses 3D video as point data has appeared, but this requires a larger amount of data than conventional 2D images. Therefore, in order to serve 3D point cloud content to users, various technological developments such as highly efficient encoding / decoding and storage, transfer, etc. are required. In this paper, V-PCC bit stream created using V-PCC encoder proposed in MPEG-I (MPEG-Immersive) V-PCC (Video based Point Cloud Compression) group, It is defined by the MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard, and provides to be composed of segments. Also, in order to provide the user with the information of the 3D coordinate system, the depth information parameter of the signaling message is additionally defined. Then, we design a verification platform to verify the technology proposed in this paper, and confirm it in terms of the algorithm of the proposed technology.

• Korean Journal of Construction Engineering and Management
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• v.20 no.2
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• pp.13-27
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• 2019

While temporary construction work applies to a temporary facility, it has a high use frequency during the construction period accounting for around 10% of the construction cost, it requires systematic management. However, construction inspection information of temporary construction work often has no special specification in the design documents and specification items, with the items on various standards also being formidable. Because of this, related inspection are likely to be performed inefficiently with a high probability for occurrence of human errors when quality inspection is conducted for the temporary construction work. In the present study, therefore, apply to the electronic operation support system capable of supporting implementation of inspection of providing related information for the contemporary construction work. To achieve this, a prototype is developed by using IDEF0 to identify information flow by process and organizing EPSS-based quality inspection Task. And then, efficiency of the quality inspection and information accessibility for temporary construction work are to be improved by verification method of Sample Project.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.2
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• pp.103-108
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• 2019

A new state-of-the-art sloshing research equipment has developed to perform the model test of LNG tanks for the safer design of LNG cargo containment system in violent sloshing phenomena. This sloshing test system has developed by the Samsung Ship Model Basin (SSMB) and thoroughly verified. The accuracy of the motion of hexapods equipment for the excitation of a model tank has been verified. The maximum displacement in six degrees of freedom, harmonic motions of various frequencies, and irregular motions in wave conditions are measured and compared with input signals. In order to confirm the reliability of the post-processing program for measured impact pressure, the post-processed results were compared with those of the reference institute. A benchmarking sloshing test using 1/50 scale model of 160K LNGC tank was conducted for the verification of the whole testing system. The partial filing levels were considered. As a result of the experiment, it is confirmed that the results are in good agreement with those of the reference institute.