• Journal of Astronomy and Space Sciences
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• v.38 no.4
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• pp.203-215
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• 2021

The auroral observation has been started at Jang Bogo Station (JBS), Antarctica by using a visible All-sky camera (v-ASC) in 2018 to routinely monitor the aurora in association with the simultaneous observations of the ionosphere, thermosphere and magnetosphere at the station. In this article, the auroral observations are introduced with the analysis procedure to recognize the aurora from the v-ASC image data and to compute the auroral occurrences and the initial results on their spatial and temporal distributions are presented. The auroral occurrences are mostly confined to the northern horizon in the evening sector and extend to the zenith from the northwest to cover almost the entire sky disk over JBS at around 08 MLT (magnetic local time; 03 LT) and then retract to the northeast in the morning sector. At near the magnetic local noon, the occurrences are horizontally distributed in the northern sky disk, which shows the auroral occurrences in the cusp region. The results of the auroral occurrences indicate that JBS is located most of the time in the polar cap near the poleward boundary of the auroral oval in the nightside and approaches closer to the oval in the morning sector. At around 08 MLT (03 LT), JBS is located within the auroral oval and then moves away from it, finally being located in the cusp region at the magnetic local noon, which indicates that the location of JBS turns out to be ideal to investigate the variabilities of the poleward boundary of the auroral oval from long-term observations of the auroral occurrences. The future plan for the ground auroral observations near JBS is presented.

• Journal of the Korean Chemical Society
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• v.66 no.5
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• pp.349-361
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• 2022

Because hydrotreating (HDT) of FCC gasoline is one of the important processes used to prepare such gasoline for blending, the development of a catalyst for this process is of great interest. Currently, the industrial HDT of FCC gasoline consists of two stages and the creation of a new catalyst for one-stage HDT will make this process more efficient. Recently, our group has developed the CoMo/Al₂O₃-ASA catalyst and studied the influence of Si/Al ratio on the target reactions of HDT process. Despite the high selectivity and activity, the catalyst with ASA is not applicable in industry because of its low strength. The present work moves forward to study the influence of the ASA content in the catalyst support and clarify the possibility to develop the catalyst that combines high activity and selectivity in HDT reactions with successful performance. Here we show that the CoMo catalyst with ASA/Al₂O₃ molar ratio 1/1 in the support is the best combination for FCC gasoline hydrotreatment due to exceptional properties of the catalyst composition.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.238-246
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• 2022

The purpose of this study was to draw the conclusion that the appearance of 'Gyuncheonak' in the lyrics of Jangsaengboyeonjimu and that 'Gubyeonjakdaedo' are related to Gucheondo in Taoism and Buddhism. Jangsaengboyeonjimu is a Jeongjae, which has a variety of dance moves and composition changes compared to any other royal Jeongjae, and is recorded in detail that the formation changes nine times. the lyrics and Gubyeonjakdaedo were compared. The relationship was inferred by applying the Gubyeonjakdaedo of the record book to the Gucheondo Island of Taoism and Buddhism. It is believed that in 1829, Crown Prince Hyo Myung created the work by putting the meaning of Gyuncheondo in Taoism and Buddhism in the song and Gubyeonjakdaedo.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.5
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• pp.221-228
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• 2022

With the application of artificial intelligence technology, robots can provide efficient services in real life. Unlike industrial manipulators that do simple repetitive work, this study presented design methods of 6 degree of freedom robot arm and intelligent object search and movement methods for use alone or in collaboration with no place restrictions in the service robot field and verified performance. Using a depth camera and deep learning in the ROS environment of the embedded board included in the robot arm, the robot arm detects objects and moves to the object area through inverse kinematics analysis. In addition, when contacting an object, it was possible to accurately hold and move the object through the analysis of the force sensor value. To verify the performance of the manufactured robot arm, experiments were conducted on accurate positioning of objects through deep learning and image processing, motor control, and object separation, and finally robot arm was tested to separate various cups commonly used in cafes to check whether they actually operate.

• Communications for Statistical Applications and Methods
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• v.29 no.1
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• pp.85-101
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• 2022

Derivative-linked securities (DLS) is a type of derivatives that offer an agreed return when the underlying asset price moves within a specified range by the maturity date. The underlying assets of DLS are diverse such as interest rates, exchange rates, crude oil, or gold. A German 10-year bond rate-linked DLS and a USD-GBP CMS rate-linked DLS have recently become a social issue in Korea due to a huge loss to investors. In this regard, this paper accounts for the payoff structure of these products and evaluates their prices and fair coupon rates as well as risk measures such as Value-at-Risk (VaR) and Tail-Value-at-Risk (TVaR). We would like to examine how risky these products were and whether or not their coupon rates were appropriate. We use Hull-White Model as the stochastic model for the underlying assets and Monte Carlo (MC) methods to obtain numerical results. The no-arbitrage prices of the German 10-year bond rate-linked DLS and the USD-GBP CMS rate-linked DLS at the center of the social issue turned out to be 0.9662% and 0.9355% of the original investment, respectively. Considering that Korea government bond rate for 2018 is about 2%, these values are quite low. The fair coupon rates that make the prices of DLS equal to the original investment are computed as 4.76% for the German 10-year bond rate-linked DLS and 7% for the USD-GBP CMS rate-linked DLS. Their actual coupon rates were 1.4% and 3.5%. The 95% VaR and TVaR of the loss for German 10-year bond rate-linked DLS are 37.30% and 64.45%, and those of the loss for USD-GBP CMS rate-linked DLS are 73.98% and 87.43% of the initial investment. Summing up the numerical results obtained, we could see that the DLS products of our interest were indeed quite unfavorable to individual investors.

• SUVANNABHUMI
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• v.13 no.2
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• pp.109-134
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• 2021

Indonesia has undergone the rapid deforestation largely as a result of practical consequences of human overexploitation of the forest. Between 1950 and 2015, around 43% of the forest area in Indonesia had been lost (68.0 million hectares). The process of deforestation has partly been a response to the rapidly intensifying 'global' and 'domestic' economic demands. Deforestation in Indonesia is also indirectly due to 'materialism-driven' value system and the corresponding weakening of Indonesian ethics. Therefore, given that socio-cultural expressions of modern Indonesian value systems have mostly taken place within a framework of Islam, the aim of the paper is to attempt to find Islamic ethics in general, which can provide the basis of ecological ethics to prevent rapid deforestation in Indonesia. The paper is composed of the followings. First, following the 'Introduction', it outlines the historical process of deforestation in Indonesia and also its corresponding socio-economic contexts. Then it moves on to talk about ecological ethics in general, thereby emphasizing that the phenomenological problem of deforestation needs to be conceived at a philosophical level beyond ecological phenomena. After discussing the ecological ethics, the paper proceeds to examine Islamic ethics as a canonical framework of ecological ethics in Indonesia. In doing so, it attempts to apply the Islamic ethics to the diverse Indonesian society and then considers 'Pancasila' as a potential framework for a pragmatic link between Islam ethics and Indonesian society. Having said that, in conclusion, the paper argues that there is a need for 'concrete' translation of 'Pancasila' into implementation in an Indonesian context, thereby various agents (government, policy-practitioners, concessionaires and also all the Indonesian) may agree in saying 'no' to overexploitation of the forest, to rapid depletion of the forest and to 'unsustainable' development practices.

• Journal of Broadcast Engineering
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• v.27 no.5
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• pp.629-637
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• 2022

This study is an experiment on the use of RDW(Redirected Walking) technology, which helps users to hardly feel the difference of user movement in the limited physical space and the extended virtual space when the user moves while wearing the HMD in the real world. The RDW function installed in 3D space realization software such as Unity3D is used to induce the user's redirection by slightly distorting the virtual space according to the user's point of view. However, if the RDW distortion rate is used excessively, dissonance is highly likely to occur. In particular, it is easy to make errors that cause cybersickness of users. It is important to obtain the RDW data value in the virtual environment so that the user does not feel fatigue and cybersickness even after wearing the HMD for a long time. In this experiment, it was tested whether the user's RDW was safely implemented, and item and obstacle arrangement data were obtained through this experiment. The RDW data obtained as a result of the experiment were used for item placement and obstacle placement in the virtual space.

• Structural Monitoring and Maintenance
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• v.8 no.4
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• pp.345-360
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• 2021

This paper presents an analytical approach to calculate the buckling load of the cylindrical ring structures subjected to both hydrostatic and hydrodynamic pressures. Based on the conservative law of energy and Timoshenko beam theory, a theoretical formula, which can be used to evaluate the critical pressure of buckling, is first derived for the simplified cylindrical ring structures. It is assumed that the hydrodynamic pressure can be treated as an equivalent hydrostatic pressure as a cosine function along the perimeter while the thickness ratio is limited to 0.2. Note that this paper limits the deformed shape of the cylindrical ring structures to an elliptical shape. The proposed analytical solutions are then compared with the numerical simulations. The critical pressure is evaluated in this study considering two possible failure modes: ultimate failure and buckling failure. The results show that the proposed analytical solutions can correctly predict the critical pressure for both failure modes. However, it is not recommended to be used when the hydrostatic pressure is low or medium (less than 80% of the critical pressure) as the analytical solutions underestimate the critical pressure especially when the ultimate failure mode occurs. This implies that the proposed solutions can still be used properly when the subsea vehicles are located in the deep parts of the ocean where the hydrostatic pressure is high. The finding will further help improve the geometric design of subsea vehicles against both hydrostatic and hydrodynamic pressures to enhance its strength and stability when it moves underwater. It will also help to control the speed of the subsea vehicles especially they move close to the sea bottom to prevent a catastrophic failure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.27 no.1
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• pp.69-75
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• 2023

Small communication devices used in the Internet of Things are vulnerable to various hacking because they do not apply advanced encryption techniques due to their low memory capacity or slow computation speed. In order to increase the authentication reliability of small-sized transmitters operating in 433MHz band, we introduce an RF fingerprint and adopt a convolutional neural network (CNN) as a classification algorithm. The preamble signal transmitted by each transmitter are extracted and collected using software-defined-radio to constitute a training data set, which is used for training the CNN. We tested identification of 20 transmitters in four different scenarios and obtained high identification accuracy. In particular, the accuracy of 95.8% and 92.6% was obtained, respectively in the scenario where the test was performed at a location different from the transmitter's location at the time of collecting training data, and in the scenario where the transmitter moves at walking speed.

• Journal of Korean Association for Spatial Structures
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• v.22 no.2
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• pp.57-64
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• 2022

In this paper, the physical model and governing equations of a shallow arch with a moving boundary were studied. A model with a moving boundary can be easily found in a long span retractable roof, and it corresponds to a problem of a non-cylindrical domain in which the boundary moves with time. In particular, a motion equation of a shallow arch having a moving boundary is expressed in the form of an integral-differential equation. This is expressed by the time-varying integration interval of the integral coefficient term in the arch equation with an un-movable boundary. Also, the change in internal force due to the moving boundary is also considered. Therefore, in this study, the governing equation was derived by transforming the equation of the non-cylindrical domain into the cylindrical domain to solve this problem. A governing equation for vertical vibration was derived from the transformed equation, where a sinusoidal function was used as the orthonormal basis. Terms that consider the effect of the moving boundary over time in the original equation were added in the equation of the transformed cylindrical problem. In addition, a solution was obtained using a numerical analysis technique in a symmetric mode arch system, and the result effectively reflected the effect of the moving boundary.