• Current Photovoltaic Research
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• 제8권1호
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• pp.17-26
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• 2020

It is clear that monocrystalline Silicon (Si) ingots are the key raw material for semiconductors devices. In the present industries markets, most of monocrystalline Silicon (Si) ingots are made by Czochralski Process due to their advantages with low production cost and the big crystal diameters in comparison with other manufacturing process such as Float-Zone technique. However, the disadvantage of Czochralski Process is the presence of impurities such as oxygen or carbon from the quartz and graphite crucible which later will resulted in defects and then lowering the efficiency of Si wafer. The heat transfer plays an important role in the formation of Si ingots. However, the heat transfer generates convection in Si molten state which induces the defects in Si crystal. In this study, a crystal growth simulation software was used to optimize the Si crystal growth process. The furnace and system design were modified. The results showed the melt-crystal interface shape can affect the Si crystal growth rate and defect points. In this study, the defect points and desired interface shape were controlled by specific crystal growth rate condition.

• 한국진공학회지
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• 제18권4호
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• pp.245-253
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• 2009

InAs/GaSb (8/8-ML) 응력초격자 (SLS)의 성장 변수를 최적화하기 위하여, 다양한 조건 및 모드에서 SLS 구조를 제작하여 고분해능 X선회절 (XRD) 특성을 분석하였다. 본 연구에서는 성장온도, V/III 분자선 비율, 성장일시정지 (growth interruption, GI) 등의 변화를 통하여 SLS 계면층의 응력 변조를 유도하였고, XRD 0차 위성피크의 변위로서 응력의 변화를 고찰하였다. XRD 분석 결과로부터, SLS의 결정성과 응력의 변화를 유발하는 주요 변수는 각각 성장온도와 V/III(Sb/Ga) 비율임을 보여 주었다. 압축변형을 가지고 있는 본 연구에서 제작한 SLS 시료는 V/III(Sb/Ga) 비율의 감소에 따라 인장변형으로 전환됨을 보여 주었으며, GI 모드 및 시간에 따라 응력이 민감하게 변함을 관측할 수 있었다. 본 연구 결과로부터, [InAs/GaSb]-SLS ([8/8]-ML)의 최적 성장온도와 V/III(Sb/Ga) 비율는 각각 $350^{\circ}C$와 20이고, 결정성을 극대화하고 응력완화를 감소시키기 위해서는 InAs 성장 직전 약 3초 동안의 GI방법이 유효함을 보였다.

• 한국결정성장학회지
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• 제15권6호
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• pp.260-262
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• 2005

Thickness optimization of heavily doped p-type seeding layer was studied to improve performance of thin film silicon solar cell. We used liquid phase epitaxy (LPE) to grow active layer of $25{\mu}m$ thickness on $p^+$ seeding layer. The cells with $p^+$ seeding layer of $10{\mu}m\;to\;50{\mu}m$ thickness were fabricated. The highest efficiency of a cell is 12.95%, with $V_{oc}=633mV,\;J_{sc}=26.5mA/cm^2$, FF = 77.15%. The $p^+$ seeding layer of the cell is $20{\mu}m$ thick. As thicker seeding layer than $20{\mu}m$, the performance of the cell was degraded. The results demonstrate that the part of the recombination current is due to the heavily doped seeding layer. Thickness of heavily doped p-type seeding layer was optimized to $20{\mu}m$. The performance of solar cell is expected to improve with the incorporation of light trapping as texturing and AR coating.

• 한국미생물·생명공학회지
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• 제20권6호
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• pp.668-676
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• 1992

Alcaligenes eutrophus에 의한 poly-Beta-hydroxybuty-rate(PHB) 생산을 최적화하기 위해서 1단계에서는 성장을 최대화하고, 2단계에서는 생산을 최대화하는 이단 유가식 배양을 채택하였다. 성장단계에서 탄소원과 질소원의 최적농도는 회분식 배양 모델로부터 결정되었는데, 각기 16.64g/l와 0.54g/l이었다. 생산단계에서 질소원의 경우, 유가식 배양실험을 통해 0.07g/l가 최적인 것으로 나타났다. 탄소원의 최적농도는 모사로부터 결정되었고 이때 최적 전환시간도 함께 결정되었다. 생산공정의 제어를 위하여 시간지연을 고려한 적응비례 되먹임제어를 이용한 결과, 탄소원 농도 및 질소원농도를 최적의 상태로 유지시킬 수 있었다.

• 대한안전경영과학회지
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• 제16권3호
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• pp.327-333
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• 2014

Changes in the business environment in which intense and sustained growth and survival must meet a variety of customer needs (Q, C, D) and business side of the enterprise for profit structure reformation is absolutely necessary for innovation activities. So far, management of innovation in method BPR, PI, OVA, 6 Sigma, Strategic Purchasing, PPM, SCM etc. are being introduced. However, they have a limit of partial optimization and improvement-oriented techniques. So this paper studied the TPI(Total Profit Innovation) application in order to derive empirical methodology to maximize profitability for the domestic S foundry factory. To this end, long-term gains through structural analysis and intensity analysis to ensure continued growth and profitability strategy are devised through management Innovation analysis. And improvement projects was presented to solve main issues of five categories(Inventory, Sales Mix, Cost, Quality Cost, Skill and Work-load) We will expect the office productivity improvement and financial performance improvement and then continually accumulate and review the results.

• Journal of Forest and Environmental Science
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• 제24권3호
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• pp.143-149
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• 2008

We conduct economic analysis of the snow damage on sugi (Cryptomeria japonica) forest stands in Toyama Prefecture, Japan. We utilize a single tree and distant independent growth simulator called "Silv-Forest." With this growth simulator, we developed an optimization model by dynamic programming, called DP-Silv (Dynamic Programming Silv-Forest). The MS-PATH (multiple stage projection alternative technique) algorithm was embedded as a searching algorithm of dynamic programming. The height / DBH ratio was used to constrain the thinning regime for snow damage protection. The optimal rotation age turned out to be 65 years for the non-restricted case, while it was 50 years for the restricted case. The difference in NPV of these two cases as the induced costs ranged from 179,867 to 1,910,713yen/ha over the rotation age of 20 to 75 years. Under the optimal rotation of 65 years, the cost became 914,226 yen/ha. The estimated annual payment based on the difference in NPV, was from 9,869 yen/ha/yr to 85,900 yen/ha/yr. All in all, 10,000 yen/ha/yr to 20,000 yen/ha/yr seems to cover the payment from the rotation age of 35 to 75 years.

• KSBB Journal
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• 제23권1호
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• pp.54-58
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• 2008

수소는 연료전지와 같은 친환경적인 용도로 인해 미래의 에너지로서 주목받고 있는데, 생물학적인 발효법은 수소의 생산을 위한 유망한 방법이다. 본 연구에서는 Enterobacter aerogenes KCCM 40146을 대상으로 수소 생산을 최대로 하기 위한 배지의 조건을 최적화하였다. 그 결과, 0.5M potassium phosphate buffer pH 6.5에서 glucose 30 g/L일 때 수소의 누적 농도가 431 $m{\ell}$로 최대값을 얻을 수 있었다. 질소원으로 peptone과 tryptone을 넣은 배지가 수소의 생산 뿐 아니라 균주의 성장에 가장 효율적이었다 한편, 미생물의 성장속도조절이 수소의 효율적 생산을 위해 중요한 실험변수임을 알 수 있었다.

• 한국결정성장학회지
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• 제23권2호
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• pp.76-80
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• 2013

For further improvement of osseo-integration of bone crystal with a dental implant, a design optimization study is carried out for various holes inside its body to deliver bioactive materials and the effect of bioactive material injection on the bone crystal growing. When bioactive material is absorbed, the bone crystal can grow into holes, which would increase the strength of implant bonding as well as a surface integration. The stress concentrations near the uppermost outlet holes were reduced with increasing the number of outlet holes. A design improvement in the uppermost outlet was shown to be effective in reducing the stress concentration. For design parameters under consideration in this study, total area of outlet of 6.38 $mm^2$ and maximum stress of 1.114 MPa, which corresponds to type 6-C. It is due to the minimization of maximum stress and total area of outlet. The design of the outlet facing down was more effective in reducing the maximum stress value compared with a horizontal symmetry.

• KSBB Journal
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• 제18권1호
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• pp.51-54
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• 2003

이 연구의 목적은 미세조류인 Chlamydomonas reinhardtii을 이용하여 수소 및 유기물의 생산을 위한 배양 조건을 최적화 하는 것이다. 세 가지 종의 균주를 조사하여 C. reinhardtii UTEX 90이 수소 생산성과 유기물 생산성 면에서 가장 우수함을 확인하였다. 최적 이산화탄소 농도 범위는 1-3% 였으며 두 종류의 미세조류 배양에 있어 대표적인 배지 (Bristol's media and TAP media)를 조사한 결과 TAP 배지에서의 세포성장이 Bristol 배지보다 더 우수함을 확인하였다. 3%의 이산화탄소 농도와 TAP 배지에서 균주를 배양하여 최대 수소 생산($0.5\mu$ mol/mg DCW)을 얻었다. 그러나 전체 유기물 생산은 Bristol 배지에서 두 배 이상 생산되었다.

• 한국초전도ㆍ저온공학회논문지
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• 제23권3호
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• pp.41-44
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• 2021

We developed an optimization process of the pulsed laser deposition method to grow epitaxial CeCoIn₅ thin films on MgF₂ substrates. The effects of different deposition parameters on film growth were extensively studied by analyzing the measured X-ray diffraction patterns. All the deposited films contained small amounts of CeIn₃ impurity phase and misoriented CeCoIn₅, for which the c-axis of the unit cell is perpendicular to the normal vector of the substrate surface. The deposition temperature, target composition, laser energy density, and repetition rate were found effective in the formation of (00l)-oriented CeCoIn₅ as well as the undesired phases such as CeIn₃, misoriented CeCoIn₅ along the (112) and (h00). Our results provide a set of deposition parameters that produce high-quality epitaxial CeCoIn₅ thin films with sufficiently low amounts of impurity phases and can serve as a reference for future studies to optimize the deposition process further.