• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.19-24
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• 2015

We introduce an optimization of the number of base station antennas in massive multiple-input multiple-output (MIMO) wireless powered communication network (WPCN). We use channel hardening property of massive MIMO system to approximate channel gain in terms of the number of base station antennas. Then, we find an optimal solution by partial differential and obtain a closed form solution by using Lambert-W function. The simulation results show that the approximation and the method of solving the optimization problem are reasonable, and the optimal solution of proposed scheme is almost identical to the optimal number of base station antennas by the exhaustive search method.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.381-386
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• 1994

Recently, the design and construction of massive concrete structures are increased. But, the temperature rise within a large concrete mass make the construction of massive concrete structures be very difficult. Therefore, in Seohae Grand Bridge Project, the field measurement of hydration heat for the massive concrete footings(11$\times$22$\times$4m) was carried out. It was shown to be possible to construct the massive concrete footing successfully by application of pipe cooling system. And the measurement results showed that standard code for concrete practice was very conservative.

• Journal of Astronomy and Space Sciences
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• v.29 no.1
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• pp.93-96
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• 2012

There are observational difficulties determining dynamical masses of binary star components in the upper HR diagram both due to the scarcity of massive binary systems and spectral and photometric contamination produced by the strong wind outflows in these systems. We discuss how variable X-ray emission in these systems produced by wind-wind collisions in massive binaries can be used to constrain the system parameters, with application to two important massive binaries, Eta Carinae and WR 140.

• Journal of the Korean earth science society
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• v.31 no.1
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• pp.18-35
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• 2010

Facies analysis of the Late Triassic Hajo Formation, the lowest stratigraphic unit in the Chungnam Basin, shows that the lower part is composed mainly of breccias or conglomerates; the middle part, conglomerates; and the upper part, conglomerates and sandstones. The formation consists of 13 facies, which include horizontally stratified clastsupported conglomerate, clast-supported massive breccia, matrix-supported massive breccia or conglomerate, matrixsupported graded conglomerate, massive pebbly sandstone, horizontally laminated sandstone, massive sandstone, graded sandstone, inversely graded sandstone, planar cross-bedded sandstone, trough cross-bedded sandstone, low angle crossbedded sandstone, and massive mudstone. These are grouped into 4 facies associations (FA). FA I consisted of clastsupported and matrix-supported massive breccias presumably deposited in the talus or upper fan delta environment. FA II consists of matrix-supported massive conglomerate and horizontally stratified clast-supported conglomerate of cobble size and it seems to have been deposited in the upper fan delta environment. FAIII consisted of matrix-supported massive conglomerate of pebble size, horizontally laminated sandstone and massive sandstone may have been deposited in the middle fan delta environment. FAIV consists of massive pebbly sandstone, horizontally laminated sandstone and massive sandstone and presumably was deposited in the lower fan delta environment. In general the Hajo Formation is interpreted to have been deposited at the talus/upper fan delta environment in early stage; it might have been deposited in the alternating environments of upper and middle fan delta in middle stage; and it seems to have been deposited in alternating environments of middle and lower fan delta in late stage.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.58-64
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• 2016

This paper proposes the efficient transmit antenna selection (TAS) scheme considering trade-off between the performance and the complexity in massive MIMO system. The massive MIMO system is a core technology to achieve performance objectives for 5 generation wireless communication. It achieve high spectral efficiency, a reliability, and a diversity gain. However many RF chains required by massive transmit antennas equipped in a base station create the problem such as high hardware cost and complexity. Therefor we investigates the transmit antenna selection scheme, in which the number of RF chains of BS is reduced, and the trade-off between the performance and the complexity is considered for proposed scheme. And, the spectral efficiency and complexity are analysed by transmit antenna selection schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.507-513
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• 2015

In this paper, we present the bit-error rate (BER) performance of quasi-orthogonal space-time block code (QOSTBC) massive multiple-input multiple-output (MIMO) system employing up to 32 transmit and receive antennas. The QOSTBC, due to its advantages in transmission rate and decoding complexity, is an important transmit diversity scheme for more than 2 transmit antennas. As massive MIMO implies very large number of antennas, practically at least more than 15 antennas, a different number of transmit and receive antennas (i.e. $2{\times}2$, $4{\times}4$, $8{\times}8$, $16{\times}16$ and $32{\times}32$) using QOSTBC for the massive MIMO system are considered. The BER performance of the massive MIMO with antennas up to $32{\times}32$ using BPSK modulation scheme is analyzed. Simulation results show that the full-rate massive MIMO systems with QOSTBC give a significant performance improvement due to increasing diversity effect, compared with previously considered massive MIMO systems.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 1999.03a
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• pp.104-107
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• 1999

$\cdot$ Although the surgical repair of massive tears of the rotator cuff is demanding procedure, the results are rewarding if technical principles are strictly followed $\cdot$ But structual healing does not parallel to technically successful repair of tears . Alternatives to direct repair might be considered for irrepairable massive tears

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.35.2-35.2
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• 2012

According to the correlations between galaxy and black hole mass, the most massive galaxies harbor the most massive black holes, with a current mass limit of.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2145-2147
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• 2015

In this letter, we investigate the performance analysis of massive MIMO systems using MRT and ZF precodings according to the number of DoF. We analyze the ergodic received SINRs with MRT and ZF precodings as closed-forms over the number of DoF normalized by the number of antennas. In simulation results, we verify the analyzed results and observe that MRT precoding is better than ZF precoding in terms of the ergodic received SINR with a small number of DoF.

• Journal of Chest Surgery
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• v.21 no.6
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• pp.1124-1136
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• 1988

Massive hemoptysis, usually rapid flooding of tracheobronchial tree and asphyxia, is associated with high mortality. We have controlled massive hemoptysis in two cases with use of bronchial artery angiography & selective bronchial artery embolization with Gelfoam particle. One case was inoperable case that was confirmed as TOF c severe pulmonary artery hypoplasia with massive hemoptysis due to hypertrophied bronchial artery and its collaterals. Another case was congenital ASD with pulmonary Aspergillosis, postop. empyema and BPF associated with massive bleeding due to erosion of hypervascular bronchial artery. We experienced dramatic improvement of general condition and cessation of massive hemoptysis for above two cases. No other problems and complication were noted during postop. hospitalization and follow-up period.