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An Analysis of the Problems and Causes of the Formation of Multicultural Families in Korea 2010-2020
Heejung Seo-Reich(Heejung Seo-Reich ),Sun Yiwei(Yiwei Sun),Yu Yinxia(Yinxia Yu),Jin Liuxi(Liuxi Jin),Wang Dehui(Dehui Wang) 영남퇴계학연구원 2022 The Journal of Toegye Studies Vol.5 No.2
This article aims to examine the status of multicultural families in Korea from 2010 to 2020, while analyzing their problems and reasons from a multi-layered perspective, to provide an academic foundation for reference in supporting a social safety system for the stable settlement of those families. Although foreign immigrants experience a certain acceptance due to economic necessity, this attitude is often only a conditional and partial acceptance that does not consider migrants as full members of the community and, moreover, sometimes even suspects them of promoting social division through their presence. This study comprehensively analyzes the current status, problems, and causes of problems in multicultural families in Korea through related data between 2010 and 2020. The problems of multicultural families are manifested mainly in economic, cultural and social terms, and each of these problems is organically interconnected. International marriages between Korean men and female immigrants from developing countries are facing a special set of issues such as unequal status of the spouses or specific problems in child’s education. These problems are serious in the sense that they are not only a temporary burden for the multicultural families, but can also affect future generations, the chances of their development and their inclusion in society. Analysis of these problems, which lie in factors of the social environment and cultural differences, can serve as a basis for countermeasures that will benefit multicultural families in Korea. The problems of multinational families must be understood and addressed in their intertwined complexity in order to find solutions that benefit not only these families, but ultimately society as a whole.
Optimal Channel Sensing for Heterogeneous Cognitive Networks: An Analytical Approach
( Heejung Yu ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.12
The problem of optimal channel sensing in heterogeneous cognitive networks is considered to maximize the system throughput performance. The characteristics of an optimal operating sensing point maximizing the overall system rate are investigated under several rate criteria including the sum rate, the minimum of the primary and secondary rates, and the secondary rate with a guaranteed primary rate. Under the sum rate criterion, it is shown that the loss by imperfect sensing is no greater than half of the sum rate achieved by the perfect time sharing approach in a two user case if the sensing point is optimally designed.
Heejung Yu,Youngchul Sung IEEE 2010 IEEE transactions on signal processing Vol.58 No.9
<P>In this correspondence, the problem of interference alignment for <I>K</I>-user time-invariant multi-input multi-output interference channels is considered. The necessary and sufficient conditions for interference alignment are converted to a system of linear equations that have dummy variables. Based on this linear system, a new algorithm for beam design for interference alignment is proposed by minimizing the overall <I>interference misalignment</I>. The proposed algorithm consists of solving a least squares problem iteratively. The convergence of the proposed algorithm is established, and its complexity is analyzed. The performance of the proposed algorithm is also evaluated numerically. It is shown that the proposed algorithm has faster convergence and lower complexity than the previous method with a comparable sum rate performance in the most practical case of two receive antennas.</P>
Heejung Yu,Youngchul Sung,Haksoo Kim,Lee, Y. H. IEEE 2012 IEEE transactions on signal processing Vol.60 No.4
<P>In this paper, the beam design for signal-space interference alignment in slowly fading multiuser multiple-input multiple-output (MIMO) interference channels is considered. Based on a linear formulation for interference alignment, a predictive beam tracking algorithm is proposed using matrix perturbation theory. The proposed algorithm, based on a mixture of iteration and update, computes interference-aligning beamforming vectors at the current time by updating the previous beam vectors based on the channel difference between the two time steps during the predictively updating phase, and yields significant reduction in computational complexity compared with existing methods recalculating beams at each time step. The tracking performance of the algorithm is analyzed in terms of mean square error and sum rate loss between the predictively updating approach and the recalculating approach, and the impact of imperfect channel knowledge is also investigated under the state-space channel model. Numerical results show that the proposed algorithm has almost the same performance as non-predictive methods in sum rate. Thus, the proposed algorithm provides a very efficient way to realize interference alignment in a realistic slowly fading MIMO channel environment.</P>
Beamforming Transmission in IEEE 802.11ac under Time-Varying Channels
Yu, Heejung,Kim, Taejoon Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-
<P>The IEEE 802.11ac wireless local area network (WLAN) standard has adopted beamforming (BF) schemes to improve spectral efficiency and throughput with multiple antennas. To design the transmit beam, a channel sounding process to feedback channel state information (CSI) is required. Due to sounding overhead, throughput increases with the amount of transmit data under static channels. Under practical channel conditions with mobility, however, the mismatch between the transmit beam and the channel at transmission time causes performance loss when transmission duration after channel sounding is too long. When the fading rate, payload size, and operating signal-to-noise ratio are given, the optimal transmission duration (i.e., packet length) can be determined to maximize throughput. The relationship between packet length and throughput is also investigated for single-user and multiuser BF modes.</P>