• Journal of Korea Water Resources Association
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• v.47 no.9
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• pp.839-852
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• 2014

This study analyzed the applicability of a rainfall downscaling algorithm in space-time multifractal framework (RDSTMF) in Korean Peninsula. To achieve this purpose, the 8 heavy rainfall events that occurred in Korea during the period between 2008 and 2012 were analyzed using the radar rainfall imagery. The result of the analysis indicated that there is a strong tendency of the multifractality for all 8 heavy rainfall events. Based on the multifractal exponents obtained from the analysis, the parameters of the RDSTMF were obtained and the relationship between the average intensity of the rainfall events and the parameters of the RDSTMF was developed. Based on this relationship, the synthetic space-time rainfall fields were generated using the RDSTMF. Then, the generated synthetic space-time rainfall fields were compared to the observation. The result of the comparison indicated that the RDSTMF can accurately reproduce the multifractal exponents of the observed rainfall field up to 3rd order and the cumulative density function of the observed space-time rainfall field with a reasoable accuracy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.541-546
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• 2004

Space-Time Coding(STC) is a technique that utilizes joint correlation of transmitted signals in both time and space domains. Through this approach, diversity and coding gains can be simultaneously obtained. In this paper, we use SPW simulation tool to implement the IEEE 802.11a system. Based on this system, OFDM system with STC and convolutional coder concatenated is implemented. The system performance is analyzed and compared with the performance of the IEEE 802.11a system. The simulation results show that the performance with concatenated codes at a data rate of 6Mbps shows approximately a 5dB gain over the system with the convolutional code only. At a data rate of 12Mbps, the performance with concatenated codes is further improved by approximately 6dB.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.11
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• pp.812-820
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• 2019

The GNSS receiver for KSLV(Korea Space Launch Vehicle)-II provides real-time navigation data as well as precise time and time interval. The precise time signals provided by the GNSS receiver that can be used for the time synchronization between onboard systems, and between the onboard systems and ground stations have the forms of the 1PPS(One Pulse Per Second) and IRIG-B(Inter-Range Instrumentation Group Time Code B) which are synchronized with UTC(Coordinated Universal Time). A signal for timing faults also informs whether the time synchronization signals are available or not. This paper describes the time synchronization signals of the GNSS receiver for KSLV-II and their performance assessment.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.265-269
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• 1994

The switching dead time avoiding a bridge leg short circuit in PWM voltage source inverter produces distortions of the controlling inverter output performance such as current waveform, voltage vector, and torque. In this paper, the influence of dead time is investigated. The on-line space voltage vector modulation method is used for current controller. It is possible to compensate dead time by space voltage vector modulation which generates additional pulse compensating voltage distortion caused by dead time. In addition, narrow pulse which is generally neglected can be compensated. All the algorithms, including field-oriented control are performed by one chip microprocessor 80C196MC and DSP TMS320C31. Experimental results probe that the proposed scheme provides a good inverter output performance.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.149-152
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• 2002

In this paper, an adaptive interference canceller (AIC) Is applied to the space-time coded DS-CDMA system in fading channels with arrival time difference from multiple transmit antennas In a CDMA system, arrival time difference causes not only inter-antenna and Inter-symbol interference but also multiple-access Interference even in a downlink. To mitigate the effect of the Interferences an AIC and ML decoding joint scheme Is proposed fur a space-time coded DS-CDMA system in which an adaptation process of tile AIC is merged in the Viterbi decoding algorithm. The performance of the proposed receiver is evaluated for the system with two transmit antennas. It is shown that the proposed receiver achieves significant performance improvement over the ML decoding receiver without the AIC

• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.11a
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• pp.109-114
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• 2006

The world has become one united world so that it is worthless to divide it into two; the East and West. In the 20th century, eastern perspectives proliferated in western science involving theology, philosophy and psychotherapy. In this time of various trends of ideas emerged minimalism, artistic and cultural current seeking simplicity and conciseness. This current of idea appeared about the time of World War II in visual art, and then expanded to other fields like music, architecture, fashion and philosophy in diverse forms. Minimalism is also presented in interior space with extreme form of simplicity and detail, revealing parts of the space as delicate and pure style with emphasis on purity of the space itself. In this research, demonstrate clear features of eastern view of space appeared in minimalism of interior design mainly in America. The reason the scope of study is limited to America is that America is the origin of minimal art and has been hub of modern design since the 1930s. The research, first, finds out the origin and conceptual idea of minimalism and features of eastern view of space. Based on this understanding, further study has been carried to discover relation of minimalistic interior space to eastern view of space and to analyze eastern characteristic expressed in minimalistic space by examination of cases pertaining to commercial space.

• Korean Institute of Interior Design Journal
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• v.24 no.4
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• pp.51-60
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• 2015

This study aims to establish the foundation for a simultaneity research, draw the potential through Bergson's simultaneity, and explore a space with the possibility of a continued change, focusing on the simultaneous process, in which physical mobility and consciousness of space last together. First, this study was focused on understanding Bergson's simultaneity, on the basis of the perspective that space needs to have more active, dynamic mobility. For understanding Bergson's simultaneity, the understanding of Bergson's duration conception, memory and perception was preceded. After that, the characteristics of simultaneity were extracted from the concepts of duration, change, memory and perception and its characteristics, which are connected to space, were analyzed. As a result, the study on simultaneity that was intensively analyzed, based on diverse cases, re-awakened the basis of value or thought, which we must aim at, in space design of the present time. This shows the possibility of another creative form that can be found in spaces of the present time and serves as the foundation to discover an essential and potential value of space in space design. Moreover, the combination of space with science, humanities, art and digital media technology demonstrated once again that there is a good possibility of approaching non-representational space that is pursued today and it is anticipated that using Bergson's simultaneity as a medium for spatial combination in their relationship would help in drawing deeper internal meaning and potential of space.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.23 no.4
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• pp.301-327
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• 2019

The proper orthogonal decomposition (POD) method for time-dependent problems significantly reduces the computational time as it reduces the original problem to the lower dimensional space. Even a higher degree of reduction can be reached if the solution is smooth in space and time. However, if the solution is discontinuous and the discontinuity is parameterized e.g. with time, the POD approximations are not accurate in the reduced space due to the lack of ability to represent the discontinuous solution as a finite linear combination of smooth bases. In this paper, we propose to post-process the sample solutions and re-initialize the POD approximations to deal with discontinuous solutions and provide accurate approximations while the computational time is reduced. For the post-processing, we use the Gegenbauer reconstruction method. Then we regularize the Gegenbauer reconstruction for the construction of POD bases. With the constructed POD bases, we solve the given PDE in the reduced space. For the POD approximation, we re-initialize the POD solution so that the post-processed sample solution is used as the initial condition at each sampling time. As a proof-of-concept, we solve both one-dimensional linear and nonlinear hyperbolic problems. The numerical results show that the proposed method is efficient and accurate.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.217-228
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• 2016

Linux it self does not support real-time. To solve this problem RTiK-Linux was designed to support real-time in the kernel space. However, since the user space does not support real-time, it is not easy to develop application. In this paper, we designed and implemented a RTiK-middleware to support real-time in the user space. RTiK-middleware provides real-time scheduling for user space through signal request period after to register process information with request period using apis on application. To evaluate the performance of the proposed RTiK-middleware, we measured the periods of generated real-time threads using RDTSC instructions, and verified that RTiK-middleware operates correctly within the error ranges of 1ms.

• Korean journal of communication and information
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• v.34
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• pp.306-340
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• 2006

Mobile communications is argued to reshape and activate the existing space by increasing 'mobile communicability en route' and 'real time interaction.' This study is designed to make an empirical analysis on how different the use of a cellular phone is in each different space. In this study, the space is divided into three distinct parts including the private, social and public space. First, spatial micro-coordination and experience of polysemy of place are widely observed in the use of a mobile phone in the private space. Secondly, it is found that a mobile phone contributes to extending the scope of social contacts which in turn compliments the existing social relationship. Moreover, a full-time intimate community that is connected via a mobile phone results in reshaping the social space. Lastly, the study shows that the usage pattern of a mobile phone varies depending on the type of public space. The technological development is envisaged to lead to more demand for the public space while facilitating the use of the public space.