• 응용통계연구
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• 제23권5호
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• pp.977-985
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• 2010

In this paper, we propose an approach to conduct partial sufficient dimension reduction with heavily unbalanced categorical predictors. For this, we consider integrated categorical predictors and investigate certain conditions that the integrated categorical predictor is fully informative to partial sufficient dimension reduction. For illustration, the proposed approach is implemented on optimal partial sliced inverse regression in simulation and data analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.377-382
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• 2001

A suboptimal control law in turbulent pipe flow is derived and tested. Two sensing variables ${\partial}p/{\partial}{\theta}\;|_w\;and\;{\partial}{\upsilon}_{\theta}/{\partial}r\;|_w$ are applied with two actuations ${\phi}_{\theta}$ and ${\phi}_r$. To test the suboptimal control law, direct numerical simulations of turbulent pipe flow at $Re_r=150$ are performed. When the control law is applied, a $13{\sim}23%$ drag reduction is achieved. The most effective drag reduction is made at the pair of ${\partial}{\upsilon}_{\theta}/{\partial}r\;|_w$ and ${\theta}_r$. An impenetrable virtual wall concept is useful for analyzing the near-wall suction and blowing. The virtual wall concept is useful for analyzing the near-wall behavior of the controlled flow. Comparison of the present suboptimal control with that of turbulent channel flow reveals that the curvature effect is insignificant.

• 한국염색가공학회지
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• 제21권3호
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• pp.26-36
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• 2009

The objective of this study is to investigate the elution characteristics of the partial dispositioned hollow nylon filament and the mechanical properties of the eluted fabrics according to the weight reduction conditions. For this purpose, the partial dispositioned nylon/PET composite filament, SDY 70d/48f was prepared, and warp beam was also prepared on the sizing machine using these yarns. Four kinds of woven fabrics were designed with different warp and weft densities and these fabrics specimens were eluted with weight reduction conditions of two kinds of NaOH concentration (30, 40g/l), three kinds of weight reduction temperature (50, 60, $85^{\circ}C$) and two kinds of weight reduction time (30, 60min). The eluting rates of these fabrics specimens were analysed with various weight reduction conditions. The eluting characteristics of these fabrics were discussed with the cross-section of nylon hollow filament measures by SEM. Finally, the mechanical properties of the partial dispositioned hollow nylon fabrics were measured and discussed with various weight reduction conditions.

• 한국분말재료학회지
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• 제31권2호
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• pp.163-168
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• 2024

As the demand for lithium-ion batteries for electric vehicles is increasing, it is important to recover valuable metals from waste lithium-ion batteries. In this study, the effects of gas flow rate and hydrogen partial pressure on hydrogen reduction of NCM-based lithium-ion battery cathode materials were investigated. As the gas flow rate and hydrogen partial pressure increased, the weight loss rate increased significantly from the beginning of the reaction due to the reduction of NiO and CoO by hydrogen. At 700 ℃ and hydrogen partial pressure above 0.5 atm, Ni and Li₂O were produced by hydrogen reduction. From the reduction product and Li recovery rate, the hydrogen reduction of NCM-based cathode materials was significantly affected by hydrogen partial pressure. The Li compounds recovered from the solution after water leaching of the reduction products were LiOH, LiOH·H₂O, and Li₂CO₃, with about 0.02 wt% Al as an impurity.

• 한국분말재료학회지
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• 제20권3호
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• pp.174-179
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• 2013

The study on the fabrication of iron powder from forging scales using hydrogen gas has been conducted on the effect of hydrogen partial pressure, temperature, and reactive time. The mechanism for the reduction of iron oxides was proposed with various steps, and it was found that reduction pattern might be different depending on temperature. The iron content in the scale and reduction ratio of oxygen were both increased with increasing reactive time at 0.1atm of hydrogen partial pressure. On the other hand, for over 30 minutes at 0.5 atm of hydrogen partial pressure, the values were found to be almost same. In the long run, iron metallic powder was obtained with over 90% of iron content and an average size of its powder was observed to be about $100{\mu}m$.

• ETRI Journal
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• 제34권2호
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• pp.268-271
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• 2012

The high peak-to-average power is one of the main drawbacks in OFDM systems. This letter proposes a partial shift mapping (PSM) method for peak power reduction in OFDM systems. By utilizing the properties of the discrete Fourier transform, the proposed method generates a set of candidate signals without additional complex multiplication and selects the one with minimum peak power for transmission. Analyses and simulations confirm that the PSM method achieves satisfactory peak power reduction performance and low complexity compared with other kindred methods, for example, selected mapping and partial transmit sequences.

• 대한수학회논문집
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• 제32권3호
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• pp.745-763
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• 2017

The Borel-Serre partial compactification gives cofinite models for the proper classifying space for arithmetic lattices. Non-arithmetic lattices arise only in semisimple Lie groups of ${\mathbb{R}}$-rank one. The author generalizes the Borel-Serre partial compactification to construct cofinite models for the proper classifying space for lattices in semisimple Lie groups of ${\mathbb{R}}$-rank one by using the reduction theory of Garland and Raghunathan.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2825-2826
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• 2009

• 스마트미디어저널
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• 제3권1호
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• pp.39-45
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• 2014

제곱연산은 승수와 피승수가 동일한 곱셈의 특수한 경우로 병렬 제곱기의 부분곱 행렬에서 부분곱 비트들은 대칭을 이룬다. 이런 특성을 이용하여 부분곱을 폴딩(folding), 쉬프트, 재배열하여 부분곱 비트의 수와 부분곱 행렬의 최대높이들 감소시킨다. 본 논문에서는 제어신호에 따라 unsigned와 signed 제곱기로 동작하는 겸용 제곱기의 효율적인 설계 방법을 제안한다. 기존 겸용 제곱기와 달리 자리수(weight)가 다른 특정 부분곱 비트들의 덧셈에 대해 덧셈기를 사용하지 않고 계산하는 방법을 제안한다. 시뮬레이션을 통해 제안한 겸용 제곱기는 기존 겸용 제곱기와 비교하여 면적은 약 18%, 지연시간(propagated delay time)은 약 11%, 전력소모는 약 9% 감소시킬 수 있음을 보인다.

• Advances in Energy Research
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• 제3권3호
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• pp.167-179
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• 2015

This paper presents a techno-economic analysis of a partial repowering scheme for an existing 210 MW coal fired power plant by integrating a gas turbine and by employing waste heat recovery. In this repowering scheme, one of the four operating coal mills is taken out and a new natural gas fired gas turbine (GT) block is considered to be integrated, whose exhaust is fed to the furnace of the existing boiler. Feedwater heating is proposed through the utilization of waste heat of the boiler exhaust gas. From the thermodynamic analysis it is seen that the proposed repowering scheme helps to increase the plant capacity by about 28% and the overall efficiency by 27%. It also results in 21% reduction in the plant heat rate and 29% reduction in the specific $CO_2$ emissions. The economic analysis reveals that the partial repowering scheme is cost effective resulting in a reduction of the unit cost of electricity (UCOE) by 8.4%. The economic analysis further shows that the UCOE of the repowered plant is lower than that of a new green-field power plant of similar capacity.