• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.56-59
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• 2011

The process conditions for high efficiency industrial crystalline Si solar cells with selective emitter were optimized. In the screen printed solar cells, the sheet resistance must be 50-60V/sq. because of metal contact resistance. But the low sheet resistance causes the increase of the recombination and blue response at the short wavelength. Therefore, the screen printed solar cells with homogeneous emitter have limitations of efficiency, and this means that the selective emitter must be used to improve cell efficiency. This work demonstrates the feasibility of a commercially available selective emitter process, based on screen printing and conventional diffusion process. Now, we improved cell efficiency from 18.29% to18.45% by transition of heavy emitter pattern and shallow emitter doping condition.

• 한국유기농업학회지
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• 제30권3호
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• pp.351-374
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• 2022

In recent years, the development of rice industry has been highly valued by the state. In hubei area, due to the development of the modernization and the shortage of labor, traditional way of rice cultivation methods is facing serious challenges, and economic benefits have become the decisive factor for the effective promotion and application of rice cultivation methods. According to the research results, first, in the input-side analysis, in the CCR model, D5, D12, D26, D28, D32, D36 farmers with high efficiency appear. The analysis result shows that among the 60 farmers, the average efficiency is 89%, and there is an inefficiency of 11%. In the BCC model, 14 farmers were identified as high-efficiency farmers, with an average efficiency of 0.9453. Second, in direct seeding cultivation of rice, the average scale efficiency is 0.9227, while the average pure technical efficiency is 0.9644. This shows that the effect of scale efficiency is greater than that of purely technical factors, ignoring the reasons for the low operational efficiency of direct seeding cultivation farmers. It can be predicted that with the further deepening of farmers' understanding of this planting mode, the proportion of rice direct seeding may be further expanded in the future. Relevant agricultural departments should further promote this technology to farmers, study the direct seeding technology using scientific methods, and evaluate the changes of this cultivation mode. The agricultural departments of government should concern about the climate risk assessment of direct seeding rice, the environmental impact assessment caused by the extensive use of herbicides, the application of mechanical technology in the process of direct seeding, the lodging of direct seeding rice, and other related issues.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.16-27
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• 2015

Holography technology which was developed by Dennis Gabor (1900~1979) in 1948 is a technology to record wave planes of actual 3D objects. It is known as the only technology which can express 3D information most perfectly close to human-friendly. Holography technology is widely used in advertisement, architecture and arts as well as science technology areas. Especially, digital holographic print which is an applied area is greatly used in military map, architecture map and cultural asset restoration by printing and reproducing 3D information. Holography is realized by recording and reproducing the amplitude and phase information on high resolution film using coherent light like laser. Recording materials for digital holographic printer are silver halide, photoresist and photopolymer. Because the materials have different diffraction efficiency according to film characteristics of each manufacturer, appropriate guide lines should be suggested through efficiency analysis of each film. This paper suggests appropriate guide lines through the diffraction efficiency measurement of silver halide which is a holographic printer recording medium. And the objective of this study is to suggest appropriate guide lines through diffraction efficiency analysis of Ultimate 08-C and PFG-03C which are commercially used. The experiment was prepared by self-diffraction efficiency system which measures the strength with the defector by penetrating RGB recording medium and concentrating diffracted beams through collimating lens. The experiment showed Geola's PFG-03C which is a silver halide for full color has price/performance advantage in optical hologram recording, but recording angles and reproduction angles are irregular for digital holographic printer recording. Ultimate's Ultimate08-C for full color shows its diffraction efficiency is relatively stable and high according to recording angles and laser wavelength.

• 기술혁신학회지
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• 제12권1호
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• pp.70-87
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• 2009

최근 유가급등, 실물경제 위기 및 에너지 환경 위기 시대에 직면하여 공공부문에서의 효율성 증대에 대한 요구는 높아지고 있다. 그간 국가연구개발사업의 효율성은 개별 사업별 절대적 성과치를 근거로 재량적으로 판단되어 온 경우가 많은 점을 인식하고, 본 연구는 사업별 비교를 통해 원자력연구개발사업의 상대적 효율성을 도출함으로써 객관적 결과를 도출함을 목적으로 하였다. 본 연구를 수행하기 위해 교육과학기술부 주요 사업인 기초연구개발사업, 특정연구개발사업 및 원자력연구개발사업의 성과보고서에 제시된 자료를 활용하였고, 문헌검토와 관련이론을 통해 분석방법 및 모형을 설계하였다. 한편 상대적 효율성을 판단하기 위하여 자료포락분석법을 활용하였으며 이의 분석결과를 토대로 원자력연구개발사업의 효율성 증진방안을 세부사업별로 제시하였다. 연구개발사업의 효율성 측정을 위하여 자료포락분석법이 활용된 사례가 없는 만큼, 동 분석법의 한계를 극복할 수 있는 개선된 자료포락분석법이 적용된다면 연구개발사업의 효율적 관리에 기여할 것으로 기대한다.

• 기술혁신연구
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• 제22권2호
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• pp.77-104
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• 2014

중소기업 R&D지원은 정책적으로 매우 중요하며 예산 또한 매년 증가하고 있다. 본 연구에서는 중소기업 R&D지원에 대한 성과를 종합적이고 체계적으로 분석할 수 있는 새로운 성과분석 방법을 제안하며 이 모델을 기반으로 중소기업청의 대표적인 R&D지원 사업에 대하여 실증분석하였다. 중소기업 R&D지원사업의 성과는 시차(time-lag)를 두고 발생하는데 이때, 단기적인 성과를 효율성, 중 장기적인 성과를 효과성으로 측정하였다. 효율성과 효과성을 나타내는 지표는 과거 선행연구를 기반으로 선정했으며 분석대상 사업별 사업목적, 취지, 내용 등의 특성을 반영하기 위해 지표별 가중치를 도출하였다. 이렇게 효율성과 효과성의 최종 점수가 도출되고 각 사업별 성과의 차이를 통계 검정하였다. 분석 결과, 중소기업청의 5개 R&D지원사업의 효율성은 통계적으로 유의한 차이를 나타냈으며 효과성은 통계적으로 차이가 없었다. 효율성 점수는 전반적으로 낮게 나타나며 효과성 점수는 보통이상으로 높은 수준을 보였다. 중소기업청의 R&D지원사업은 대체로 단기적인 성과인 효율성이 낮아 R&D수행상의 비효율을 초래하는 것으로 나타나는 반면, 중 장기적인 효과성에 대한 기대는 높아 R&D수행을 통한 사회경제적 파급효과는 클 것으로 예상된다. 그러나 효율성이 개선되지 않고는 지속적인 성과를 기대하기 힘들기 때문에 이에 대한 정책적 노력이 필요하다.

• 한국환경과학회지
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• 제11권1호
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• pp.69-74
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• 2002

This study was performed to evaluate an applicability of the SMMCMAS system for reuse of the sewage from spa area and was operated to HLR(Hydraulic loading rate) of 211.3 to 126.8 $\ell$/㎥/d. The operating HRT(Hydraulic retention time) ranges were 2.5 to 1.5 hours. Conclusions are as follows; At the optimum HLR of 158.5 $\ell/\m^2$/d (HRT of 2.0 hours), the maximum BOD removal efficiency was 94% and the effluent BOD concentration was 1.1mg/$\ell$ in result. As the HLR was increased to 211.3 $\ell/\m^2$/d, BOD removal efficiency was decreased to 75% and BOD removal efficiency was also reduced to 74% at lower HLR of 126.8 $\ell/\m^2$/d. It shows that the maximum BOD removal efficiency occurs at an optimum HLR value and that the removal efficiency decreases when the HLR is either higher or lower than the optimum value. Sludge production rates were ranged 0.01 to 0.24gVSS/gBODrem/d and accomplished to 0.01gVSS/gBODrem/d at the optimum HLR of 158.5 $\ell/\m^2$/d.

• 전자공학회논문지
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• 제51권7호
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• pp.26-36
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• 2014

IMT-Advanced 시스템을 효율적으로 서비스하고 시스템 효율을 증대시키기 위해서는 능동위상 배열구조의 안테나 시스템이 요구된다. 능동위상 배열 구조는 다수의 송수신 모듈과 다수의 복사소자로 구성되어 시스템의 효율을 증대시킬 수 있으며, 시스템을 구현하기 위해서는 초소형 고효율 송수신 모듈이 핵심이다. 최종 출력과 밀접한 관련이 있는 송신모듈의 전력증폭기는 기지국 시스템의 효율을 결정하는 핵심요소이다. 본 논문에서는 IMT-Advanced 능동위상배열 시스템에 적합한 초소형 고효율 송수신 모듈을 설계하고 구현하고자 하였다. 송수신 모듈은 온도보상 회로를 구현하여 이득 오차를 줄였으며, 선형화기는 소형화를 위하여 아날로그 방식으로 구현하였다. 초소형 고효율 전력증폭기를 구현하기 위해서 GaN MMIC Doherty 구조로 구현하였다. 구현된 송수신모듈은 $40mm{\times}90mm{\times}50mm$ 크기로 구현되었으며, LTE band 7에서 47.65 dBm의 출력을 가졌다. 실제 운용전력인 37 dBm에서 40.7%의 효율과 12 dB이상의 선형성 개선도를 보였다. 수신부의 잡음지수는 1.28 dB이하로 설계규격을 만족하였으며, 송수신 모듈의 이득과 위상은 6 bit로 제어로 최대 오차는 각각 0.38 dB와 2.77 degree를 보였다.

• 한국가시화정보학회지
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• 제18권3호
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• pp.77-83
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• 2020

A uniflow cyclone has simple structure with a single channel in one direction. The one directional particle removal enables the uniflow cyclone to have compact size and low pressure drop. However, it has low collection efficiency compared to conventional cyclones. In this study, the effect of primary geometry on the performance of a uniflow cyclone with swirl vane is numerically investigated for the design of high performance uniflow cyclone. It is found that as the vortex finder diameter is increased, the pressure drop and the collection efficiency are decreased. Also, the same trend is predicted when the vortex finder height is increased. The best collection efficiency is predicted to be obtained when the vortex finder height is equal to the diameter of a cyclone. Reducing the body height by half will increase the pressure drop by 41%. When the body height is decreased, the collection efficiency is first increased and then decreased. The best collection efficiency is obtained when the body height is 4~5 times the cyclone diameter. Overall, the particle collection efficiency is highest when the Dν/D is equal to 0.3. But, the pressure drop is as high as 1592 Pa. Considering both collection efficiency and pressure drop, the best design is when Dν/D, Hν/D, and Hb/D are equal to 0.5, 1, and 5, respectively.

• 한국군사과학기술학회지
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• 제22권1호
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• pp.106-123
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• 2019

Demand for performance analysis is increasing for efficient use of limited budgets such as improving investment efficiency and strategic budget allocation in accordance with the continuous increase demand of R&D budget for developing advanced weapon systems in the future battlefields. In accordance with the Act on the Performance Evaluation and Performance Management of the National R&D Projects established in March 2006, the performance analysis has been conducted for the systematic management and utilization of the R&D project performance. It was recognized as a project to achieve self-defense through strengthening the weapons system development capability, however, efficiency evaluation of Defense R&D projects was not much emphasized. Research on the efficiency analysis of defense R&D projects has been conducted in recent years, but most studies focused on corporate efficiency and productivity of defense companies. In this study, we analyzed the three-stage performance of defence R&D projects based on the logical model using the data envelope analysis(DEA) model. We also analyzed performance analysis from various perspectives through R&D type, technology classification and performance model. This study is expected to help defense department improve defense R&D projects and make decision.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권10호
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• pp.2732-2749
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• 2023

Device-to-Device (D2D) communication has received increasing attention and been studied extensively thanks to its advantages in improving spectral efficiency and energy efficiency of cellular networks. This paper proposes a novel relay selection algorithm for multi-hop full-duplex D2D communications underlaying cellular networks. By selecting the relay of each hop in a reverse manner, the proposed algorithm reduces the heavy signaling overhead that traditional relay selection algorithms introduce. In addition, the social domain information of mobile terminals is taken into consideration and its influence on the performance of D2D communications studied, which is found significant enough not to be overlooked. Moreover, simulations show that the proposed algorithm, in absence of social relationship information, improves data throughput by around 70% and 7% and energy efficiency by 64% and 6%, compared with two benchmark algorithms, when D2D distance is 260 meters. In a more practical implementation considering social relationship information, although the proposed algorithm naturally achieves less throughput, it substantially increases the energy efficiency than the benchmarks.