• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.23-28
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• 2010

We propose a reference vector diversity method in multi-cell multi-user uplink system with the subspace interference alignment to obtain higher sum rate capacity. The proposed method transmits several reference vectors before the data transmission, and selects the best reference vector to maximize the cell sum rate. The proposed method provides higher sum-rate capacity compared with the previous interferenc alignment. Simulation result exhibits the proposed method improves the sum-rate capacity by 60%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.318-324
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• 2011

In this paper, three coordinated random beamforming (CRBF) schemes are analyzed in a two-cell symmetric interference channel. A simple partial coordination of RBF with base station selection (BSS) is shown to achieve the same average sum rate performance of CRBF with joint encoding (JE). To improve the sum rate performance further, we also propose a transmission mode selection (TMS) between the BSS and JE which is shown to have additional sum rate gain for the large number of users. Simulation results verify the eectiveness of the proposed CRBF schemes and accuracy of the proposed analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.512-512
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• 2012

최근 저온 대기압 플라즈마 장치의 개발로 대기 및 수질 환경, 바이오 메디컬분야로의 응용 연구가 활발히 진행되어 공기 중 플라즈마의 살균 및 정화효과에 대한 많은 결과가 발표되어 왔다. 본 연구는 면방전 구조의 DBD플라즈마 소스를 제작하여 He과 Ar 기체를 유입하여 미생물인 E.Coli의 변화를 관찰하였다. 면방전 구조의 DBD플라즈마 소스는 1.8 mm 두께의 유리기판위에 포토리소그라피 공정으로 미소전극을 형성하여 고밀도의 방전 셀을 형성하였으며 방전시 발생하는 열 효과를 제어하기 위하여 냉각장치를 제작하여 장착했다. 또한 유리기판과 포토 리소그라피 공정은 방전영역에 제한없이 다양한 크기의 소스제작이 가능하다. 셀 피치가 $400{\mu}m$이며 $cm^2$ 당 200여개의 방전 셀로 구성되어 있어서 기존 메쉬타입의 DBD플라즈마 장치에 비해 균일하게 플라즈마를 조사할 수 있으며 플라즈마 제트 장치에 비해서는 넓은 면적을 동시에 조사할 수 있게 되었다. Ar 과 He기체를 3 L/min의 유량으로 방전공간에 유입하면서 1kV의 구동전압으로 플라즈마를 발생 하였으며, 플라즈마의 조사시간을 20 s, 40 s, 60 s 간격으로 변화를 주어 E.Coli의 변화를 관찰하였다.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.189-194
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• 2011

Si-cell was prepared with various types owing to the etching times textured by the KOH etching solution. The pn junction for solar cell was prepared on p-type Si wafer by the furnace using the $POCl_3$ and oxygen mixed precursor, and the metalization was done using by the Al back electrode and Ag front electrode. Textured Si surface was etched by the pyramid formation. The efficiency and the fill factor was increased in the Si-cell with a large size of pyramids, because of the series resistances decrease depending on the increasing of the photon absorbance. Increasing of the absorbance occurred the induction of the short current and open voltage, and then the efficiency was increased.

• Education of Primary School Mathematics
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• v.1 no.2
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• pp.97-108
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• 1997

대부분의 사람들은 수를 이해하면서도 인류가 수 개념을 형성하는데 얼마나 어려웠으며, 얼마나 많은 역사적 경로를 통하여 이루어진 것인가는 모르고 있다. 버틀랜드 럿셀(B. Russell, 1872-1970)이 "한 쌍의 정과 이틀이라는 날짜가 모두 2라는 수의 구체적인 보기임을 인류가 깨닫게 되기까지에는 아찔하리 만큼 길고 긴 세월이 흘러야 했다." 라고 말할 만한 이유가 있는 것이다 동물들은 사물의 개수조차도 셀 수 없다고 한다. 다른 동물에 비해 아주 영리한 까마귀만이 10정도의 숫자를 셀 수 있다고 한다. 이렇듯 수를 센다는 것 자체가 지능을 나타내는 지표가 된다. IQ에 수 개념을 측정하는 항목이 있는 것은 당연하다 하겠으며, 초등학생들이 수 개념의 이해에 많은 애로점이 있을 것이라 예상할 수 있다.(중략) 수 있다.(중략)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.160-160
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• 2013

본 실험에서는 CIGS 흡수층을 스퍼터링 방식과 급속열처리 장비를 이용한 2-step 방식을 이용하여 형성시켰다. 전구체는 DC 스퍼터링 방법으로 $Cu_{0.75}Ga_{0.25}/In$의 다층 전구체를 구성 후, 독성이 없는 셀레늄 팰릿을 graphite 상자에 넣어 급속열처리 장비로 온도를 $475{\sim}680^{\circ}C$로 온도를 조절하면서 셀렌화 하였다. 이렇게 구성된 CIGS 흡수층의 특성을 scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray differection (XRD)를 통해서 측정을 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1903-1913
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• 2016

In this paper, we propose 2-stage beamformer with linear receiver in wireless backhaul downlink system where macro base station has large antenna array with sub-array structure. Also, to compare the system capacity, we apply 3-stage beamformer with zero-forcing precoder and calculate the achievable sum rate of received small cell base stations. Considering scattering and path-loss property of wireless backhaul channel, we combine precoding technique for spatial multiplexing and beamforming technique to overcome path-loss. Therefore, we design DFT-based fixed beam patterns for the first stage. The simulation results show that considering spatial multiplexing, proposed 2-stage beamformer with linear receiver can increase the achievable sum rate as well as reduce the feedback information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1161-1167
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• 2005

In this Paper, a concept of virtual smart antenna (SA) is introduced for orthogonal Sequency division multiplexing (OFDM)-based cellular systems with a frequency reuse factor equal to 1. The OFDM-based cellular system is robust to multipath channels but has a disadvantage that the intercell interference (ICI) caused by adjacent base stations is large at the edge of a cell. In this paper, after deriving the symbol timing offset estimation scheme for the OFDM signal received from multiple base stations in a quasi-static fading channel, the ICI cancellation method based on virtual smart antenna is proposed using the steering vector formed by the symbol timing offset of the desired signal and interference signals.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.443-450
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• 2006

Micelles have been used in many applications. In these applications it is of prime importance to know how the critical micelle concentration (CMC), above which the micelles are formed, depends on temperature. Up to date polynomial functions of temperature have been used to describe temperature dependence of CMC. In this article it is shown that such polynomials are inadequate tools to express thermal behavior of CMC. Hence, new equations of CMC(T) have been derived on the basis of rigorous thermodynamic equations and experimental observations on CMCs. The new equations fit CMC data excellently, and further they lead to a power law for the CMC. The exponent of the power-law expression is 2 irrespective of surfactant systems, which points to the generality of newly found equations.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.10 no.1
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• pp.14-26
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• 2011

In this paper, we've studied Optical Fiber Subscribe Transmit system. After receiving the ATM cell passing through the FIFO of the Asynchronous Transfer Method from the ATM Layer images to the VC4 signal payload passing through scrambling of the cell payload, HEC computation of the cell and inserting the Idle/Unassigned cell. At this time formed VC4 signal passing through the generating and inserting POH overhead at the same time indicating the start point of the cell by the H4 byte on the VC4 POH. This ATM cell transmits 155Mbps speed changing the optical signal after outputting the frame format at the STM-1 signal generation block through the AUG bus after generating J1 of the VC4 start point at the AU4 pointer generation block.