• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.85-88
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• 2005

Space-time code is a good solution to get transmit diversity. During the last years a number of space-time block codes have been proposed for use in multiple transmit antenna systems. This code, however, was presented only for the special case of the certain numbers of transmit antennas and the certain modulation schemes. and designed under the assumption that the transmitter has no knowledge about the channel. In this work, on the other hand, we consider the case when the transmitter has partial, but not perfect knowledge about the channel. This system can have full diversity for arbitrary number of the transmit antennas with a little bits of feedback.

• Korean Journal of Mathematics
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• v.27 no.3
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• pp.735-741
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• 2019

Let ${\mathcal{H}}$ be a complex Hilbert space and ${\mathcal{B}}({\mathcal{H}})$ the algebra of all bounded linear operators on ${\mathcal{H}}$. In this paper, we prove that if ${\varphi}:{\mathcal{B}}({\mathcal{H}}){\rightarrow}{\mathcal{B}}({\mathcal{H}})$ is a unital surjective bounded linear map, which preserves m- isometries m = 1, 2 in both directions, then there are unitary operators $U,V{\in}{\mathcal{B}}({\mathcal{H}})$ such that ${\varphi}(T)=UTV$ or ${\varphi}(T)=UT^{tr}V$ for all $T{\in}{\mathcal{B}}({\mathcal{H}})$, where $T^{tr}$ is the transpose of T with respect to an arbitrary but fixed orthonormal basis of ${\mathcal{H}}$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1180-1187
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• 2012

In this paper, joint transmission space division multiple access(JT-SDMA) scheme is proposed to mitigate inter-cell interference(ICI) in cooperative wireless communications system with limited feedback. We propose a systematic design method for a codebook consisting of a finite number of unitary matrices suitable for network multiple-input multiple-output( MIMO) channel characteristics. A centralized cluster scheduling scheme is proposed to both mitigate ICI and maximizes multiuser diversity gain with limited feedback. It is shown that the proposed JT-SDMA scheme outperforms a existing coordinated SDMA scheme even in wireless network environments where sufficient multiuser diversity order can not be provided through efficient ICI mitigation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.231-244
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• 2015

The accuracy of reference point of VLBI antenna is mandatory to perform collocation of different space geodetic techniques. In this study, we evaluated the optimal methods for the 3D circle fitting to enhance the accuracy of the reference point of VLBI antenna. Two kinds of methodologies for the orthonormal coordinate system with translation of planar observation point and the unitary coordinate transforamation were suggested and their fitting accuracies were evaluated where the orthogonal distance was calculated by residual between observation point and fitting model and the recursive calculation was performed to improve the accuracy of 3D circle fitting. Finally, we found that the methodology for the unitary coordinate transformation is highly appropriate to determine the optimal equation for azimuth-axis and elevation-axis of VLBI antenna. Therefore, the reference point of VLBI antenna with high accuracy can be determined by the intersection of the above two axises (azimuth-axis and elevation-axis). This result is expected to be utilized for a variety of researches for connection between VLBI observation results and the national control point.

• Journal of the Korean Mathematical Society
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• v.50 no.1
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• pp.189-202
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• 2013

On the unit ball of $\mathbb{C}^n$, the space of those holomorphic functions satisfying the mean Lipschitz condition $${\int}_0^1\;{\omega}_p(t,f)^q\frac{dt}{t^1+{\alpha}q}\;<\;{\infty}$$ is characterized by integral growth conditions of the tangential derivatives as well as the radial derivatives, where ${\omega}_p(t,f)$ denotes the $L^p$ modulus of continuity defined in terms of the unitary transformations of $\mathbb{C}^n$.

• Journal of Astronomy and Space Sciences
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• v.8 no.2
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• pp.149-158
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• 1991

Sixteen unitary Light curves of AR Lac in B and V are made at Yonsei University Observatory in the period of 1980-1988. Some overview findings of light variations are made. (1) The light variation outside eclipse follow none of the wave migration patterns reported by previous investigators. (2) Complicated shapes outside eclipse are apparently much reduced in the light curves of 1983-1984. This suggests than, in the future, AR Lac has a chance to attain a normal state with no complicated interactions. (3) The depths of the primary and the secondary mid-eclipses are changing year-to-year. (4) The K0 star, the larger component, has brightened by $0.^m$ 14 in V, while the G2 star has shown a fluctuation of about $0.^m$05 in V. (5) The B-V values at primary mid-eclipse have no correlation with the depth variations. (6) Independently of the increase of maximum brightness, the B-V colors in the non-eclipsed phases changed slightly over the years.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.21-29
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• 1993

For the study of relaxation processes in complex spin system, a general master equation, which can be used to simulate a vast range of pulse experiments, has been formulated using the Liouville representation of quantum mechanics. The state of a nonequilibrium spin system in magnetic field is described by a density vector in Liouville space and the time evolution of the system is followed by the application of a linear master operator to the density vector in this Liouville space. In this master equation the nuclear spin relaxation due to intramolecular dipolar interaction or randomly fluctuating field interaction is explicitly implemented as a relaxation supermatrix for a strong coupled two-spin (1/2) system. The whole dynamic information inherent in the spin system is thus contained in the density vector and the master operator. The radiofrequency pulses are applied in the same space by corresponding unitary rotational supertransformations of the density vector. If the resulting FID is analytically Fourier transformed, it is possible to represent the final nonstationary spectrum using a frequency dependent spectral vector and intensity determining shape vector. The overall algorithm including relaxation interactions is then translated into an ANSIFORTRAN computer program, which can simulate a variety of two dimensional spectra. Furthermore a new strategy is tested by simulation of multiple quantum signals to differentiate the two relaxation interaction types.

• Journal of Sasang Constitutional Medicine
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• v.9 no.1
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• pp.245-253
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• 1997

The methodology of the Oriental philosophy is deductive and that of the of Occidental philosophy is inductive. Therefore study on the Oriental philosophy must start from right comprehension of fundamental premise before detailed analysis. The writer studied the meaning of the cosmology which forms the basis of Sa-sang constitutional philosophy and the propriety of visceral assignment by Sa-sang constitution which forms the theoletiacal basis of Sa-sang constitutional medicine. The results are following ; 1. The cosmology of Lee jae-ma has the existent principle but don't have the side of the formative principie. 2. The cosmology of Lee jae-ma is not that searchs for the objective rule of nature but that centers around a human being by subjective understanding system. 3. The cosmology consists of four elements, that is mind(心), body(身), events(事), and nature(物). Among them mind and body means a human being, nature means the natural environment containing time and space, events means not that of nature but that of human being. 4. The mind and body as Yin-yang(陰陽) means the state which objects and self become one. 5. The mind as the Great-Absolute(太極) has the possibility of two interpretation, Firstly it means the state of the source of life which nature and human being become one, and secondly it means that the mind of a human being becomes the cosmos or the center of the cosmos. 6. In the visceral assignment by Sa-sang constitution the position of heart, the Great-Absolute in center is immanent within four viscera and the function of it is that the undifferentiated unitary organic body, after it is diffrentiated still serves as the unitary organic whole by mutual connection, adjustment, unification and supervision. 7. The Great-Absolute in center is divided into the Great-Absolute of mind and that of body. And the Great-Absolute of body consists of the heart and the system of blood vessel, that of mind means the self-consciousness(自我).

• Journal of Communications and Networks
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• v.18 no.6
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• pp.892-901
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• 2016

In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.

• The Journal of Industrial Distribution & Business
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• v.10 no.7
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• pp.71-82
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• 2019

Purpose - This study aims to identify the priorities of medical service quality improvement by customer satisfaction characteristics and potential customer satisfaction improvement (PCSI) index based on the dualistic quality classification of Kano Model (1984) for Comprehensive Health Screeening Center in General Hospitals and Centers only for Comprehensive Health Screening and suggest a direction for future improvement. Research design, data, and methodology - Through advanced research on health screening medical service quality, this study set four service quality factors, including tangible, human, process and supportive factors, and 39 measurement items. Based on these items, the study used 117 questions, which consist of dualistic quality factors, customer satisfaction coefficients, positive and negative questions for PCSI index and questions for current satisfaction. 300 effective samples were collected for adults in their 20s who experienced health screening service in Seoul, Gyeonggi-do and Incheon within the past two years. Collected data were input in the quality evaluation duality table to categorize quality factors and calculate customer satisfaction coefficients by Timko(1993). The study also analyzed PCSI index in comparison with current satisfaction and identified priorities in quality improvement. Results - It was found that the most urgent factors to improve the quality in both groups were adequate waiting hours and emergency response for complications, which are process factors classified as unitary quality. It is urgently needed to improve the quality as the PCSI index was high in supportive factors (complaint response team) as attractive quality in Comprehensive Health Screening Center in General Hospitals and in process factors (prevention of infection) as unitary quality in Centers only for Comprehensive Health Screening. As the PCSI index was low in space use as a tangible factor, it was found that the current level can be maintained instead of improvement. Conclusions - To improve the health screening medical service quality, it is required to focus on process factors (adequate waiting hours, emergency response for complications, prevention of infection) and supportive factors (complaint response team) among service qualities perceived by users. It is proposed to ensure continuous efforts to manage and reinforce priorities as a direction for future improvement in health screening service.