• International Journal of Naval Architecture and Ocean Engineering
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• 제9권3호
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• pp.246-255
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• 2017

The proposed design methodology represents a new approach to optimize the propeller-hull system simultaneously. In this paper, two objective functions are considered, the first objective function is Lifetime Fuel Consumption (LFC) and the other one is cost function including thrust, torque, open water and skew efficiencies. The variables of the propeller geometries (Z, EAR, P/D and D) and ship hull parameters (L/B, B/T, T and $C_B$) are considered to be optimized with cavitation, blades stress of propeller. The well-known evolutionary algorithm based on NSGA-II is employed to optimize a multi-objective problem, where the main propeller and hull dimensions are considered as design variables. The results are presented for a series 60 ship with B-series propeller. The results showed that the proposed method is an appropriate and effective approach for simultaneously propeller-hull system design and is able to minimize both of the objective functions significantly.

• International Journal of Control, Automation, and Systems
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• 제5권2호
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• pp.117-127
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• 2007

Many real world control systems usually track several control objectives, simultaneously. At the moment, it is desirable to meet all specified goals using the controllers with simple structures like as proportional-integral (PI) and proportional-integral-derivative (PID) which are very useful in industry applications. Since in practice, these controllers are commonly tuned based on classical or trial-and-error approaches, they are incapable of obtaining good dynamical performance to capture all design objectives and specifications. This paper addresses a new method to bridge the gap between the power of optimal multiobjective control and PI/PID industrial controls. First the PI/PID control problem is reduced to a static output feedback control synthesis through the mixed $H_2/H_{\infty}$ control technique, and then the control parameters are easily carried out using an iterative linear matrix inequalities (ILMI) algorithm. Numerical examples on load-frequency control (LFC) and power system stabilizer (PSS) designs are given to illustrate the proposed methodology. The results are compared with genetic algorithm (GA) based multiobjective control and LMI based full order mixed $H_2/H_{\infty}$ control designs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.402-402
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• 2011

본 연구에서는 결정질 태양전지 제작에 있어 재료비 절감과 기존의 Screen Printing 공정 기술에서의 단점을 보완하기 위한 방안으로 후면 passivation 구조와 레이저를 이용한 국부적 후면 전극 형성(Laser Fired Contact) 방법에 대한 실험을 진행하였다. 후면 passivation 층으로 SiO2/ SiNx/SiO2 삼중막 구조와 SiNx 단일막 구조를 형성시킨 후 anneal 온도에 따른 소수캐리어의 lifetime 변화를 비교하였다. LFC 형성은 2 ${\mu}m$ 두께의 Al이 증착된 기판 후면에 1,064 nm 파장의 레이저를 통해 diameter와 dot pitch 등의 파라미터를 가변 하여 실시하였다. 실험 결과 800$^{\circ}C$의 고온 열처리 후 ONO 삼중막에서의 lifetime 향상이 우세하여 SiNx 단일 막 보다 열적 안정성이 우수함을 확인하였다. LFC 결과 diameter가 40, 50, 60 ${\mu}m$로 가변된 조건에서는 40 ${\mu}m$ 일 경우와 dot pitch가 200, 500, 1,000 ${\mu}m$로 가변된 조건에서는 1,000 ${\mu}m$일 경우 610 mV의 Voc 값을 보였다. 이는 레이저를 통해 국부적으로 Al-Si 간 alloy를 형성시킴으로써 접촉 면적이 최소화됨에 따라 후면에서의 캐리어의 재결합속도를 감소시키고, passivation 효과를 극대화시키기 때문이다.

• Food Science and Biotechnology
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• 제18권1호
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• pp.36-42
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• 2009

This study was performed to develop low-fat/reduced-salt sausages (LFRSS; <3% fat and <1.5% salt) containing milk protein (whey protein concentrate, WPC, or sodium caseinate, SC) that showed the similar cooking yield and textural characteristics to those of regular-fat/salt sausage control (RFC; 20% fat and 1.5% salt) or low-fat sausage control (LFC; <3% fat and 1.5% salt). Low-fat sausages (LFS) were formulated with a 2.5% fat replacer (konjac flour:carrageenan:soy protein isolate=1:1:3) and various salt levels (0.75, 1.0, 1.25, and 1.5%). LFS had differences in color and expressible moisture (EM, %) values as compared to those of RFC. A minimum salt level of 1% and addition of nonmeat proteins were required to manufacture LFRSS that have similar characteristics to those of RFC. However, LFS with 2% milk proteins reduced the hardness and gumminess as compared to LFC. These results indicated that 1% milk protein in combined with 1% salt was a proper level for manufacturing of LFRSS.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1027-1037
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• 2017

Penetration of renewable energy sources makes the modern interconnected power systems to have more intelligence and flexibility in the control. Hence, it is essential to maintain the system frequency and tie-line power exchange at nominal values using Load Frequency Control (LFC) for efficient, economic and reliable operation of power systems. In this paper, intelligent tuning of the Proportional Integral Derivative (PID) controller for LFC in an interconnected power system is considered as a main objective. The chosen problem is formulated as an optimization problem and the optimal gain parameters of PID controllers are computed with three innovative swarm intelligent algorithms named Particle Swarm Optimization (PSO), Bacterial Foraging Optimization Algorithm (BFOA) and hybrid Bacterial Foraging Particle Swarm Optimization (BFPSO) and a comparative study is made between them. A new objective function designed with necessary time domain specifications using weighted sum approach is also offered in this report and compared with conventional objective functions. All the simulation results clearly reveal that, the hybrid BFPSO tuned PID controller with proposed objective function has better control performances over other optimization methodologies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.300-300
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• 2010

후면 패시베이션, back contact의 가변, 후면 접촉면적의 가변 등으로 Laser Fired Contact 태양전지의 효율을 증가 시킬 수 있다. 이 중 spacing의 가변으로 후면 접촉 면적을 가변 할 수 있으며, 이로 인하여 LFC 태양 전지의 효율을 높일 수 있을 것으로 전망된다. 본 연구에서는 후면 접촉 면적을 가변하였으며 이에 따른 효과를 확인하였다. series resistance가 작고, open circuit voltage 가 높은 최적의 조건을 찾는 것에 그 목적을 두었다. 실험 순서는 texturing 후, 후면에 SiNx를 10nm 증착하였으며, drive-in 방법으로 $POCl_3$을 도핑하였다. ARC후, spacing 조건 가변으로 접촉 면적을 가변시키면서 소자의 특성 변화를 비교하였다. 접촉 면적 및 spacing 조건은 5개의 set에 대하여 reference, 50%의 접촉 면적을 가지는 $150{\mu}m$ line, 10%의 접촉 면적을 가지는 $700{\mu}m$ line, 1%의 접촉 면적을 가지는 $700{\mu}m$ dot, 그리고 0.2%의 접촉 면적을 가지는 $1500{\mu}m$ dot으로 하였다. 각각의 경우에 대한 short circuit current density, fill factor, seris resistance, sheet resistance, open circuit voltage를 측정하였으며, 특히 series resistance는 각각의 경우에 대하여 $6.1m{\Omega}$, $5.1m{\Omega}$, $7.8m{\Omega}$, $10.1m{\Omega}$, 그리고 $15.7m{\Omega}$으로 측정되었다. wafer의 외각 테두리를 접촉 면적이 증가함에 따라서 sheet resistance가 증가하는 것을 확인 할 수 있었다.

• 풍력에너지저널
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• 제14권3호
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• pp.54-60
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• 2023

In order to reveal the levelized cost of energy (LCOE) of Korean and foreign wind turbines, a study was conducted for Korean onshore wind farms. Actual CapEx and OpEx data were obtained from audit reports for 26 onshore wind farms corresponding to 53.87 percent of the total onshore wind farms in Korea in the Data Analysis, Retrieval Transfer (DART) system. In addition, capacity factor (CF) data were calculated from data provided by Statistics Korea. Random numbers were generated from distributions that were fitted by the datasets, which were used as input data to perform a Monte Carlo simulation (MCS). The levelized fixed cost (LFC) and the levelized variable cost (LVC) were calculated from distributions of the CapEx, the OpEx and the CF. As a result, the LCOEs of the analyzed total Korean wind farms, and Korean and foreign wind turbines were 147, 148, and 146 USD/MWh, respectively. The averaged LCOE of Korea was estimated to be 4 USD/MWh lower than that of Japan, while it was much higher than German and global averages.

• 동아시아식생활학회지
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• 제15권4호
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• pp.386-396
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• 2005

The effects of spirulina-added salad dressing on lipid profiles and antioxidant biomarkers such as total glutathionine, TBARS value, carbonyl value, GPx, GR, SOD and paraoxonase activity in plasma or liver of mice were evaluated Sixteen male ICR mice weighing 20$\pm$2 g were divided into two groups and fed low fat ($5\%$ fat) diet (low fat control: LFC) and low fat control plus dressing diet (LFD) for eight weeks. Body weight, tissue weights of liver, heart and kidney, and the distribution of body fat deposition were not significantly different between two groups. Also, the profile of TG, TC, LDL and HDL cholesterol were similar between two groups. The DNA damage was determined using the comet assay (single cell gel assay) with alkaline electrophoresis and quantified by measuring tail length (TL). Spirulina salad dressing consumption resulted in significant decrease in lymphocyte DNA damage expressed by TL (LFC: $28.8{\mu}m$, LFD: $20.3{\mu}m$). Additionally, salad dressing consumption for 8 wks decreased the lipid peroxidation assayed by TBARS to $12.6\%$ compared with the control. The levels of antioxidant vitamins such as $\beta$-carotene were significantly higher in plasma of LFD group than those in LFC group based on HPLC method This study shows that spirulina-added salad dressing exerts degenerative disease-protective effects on oxidative DNA damage and lipid peroxidation possibly via a free radical levels.

• 대한전기학회논문지
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• 제33권3호
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• pp.100-105
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• 1984

The optimal Load-Frequency Control law is presented with the performance criterion which includes the changing rate of governor speed. The authors propose two controllers. One is a dynamic controller using the method of state augmentation and the other is a constant gain controller with use of the trace function lemma by Kleinman. For a more practical realization, a reduced-order Luenberger observer is applied in order to identify unmeasurable states and power demand. The control schemees presented here are tested through the model developed by Elgerd, and the usefulness is demonstrated.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.134.2-135
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• 2003

We examined the minimal amino acid sequence of bovine lactoferricin (Lfcin-B), a cationic peptide corresponding to residues 17-41 near the N-terminus of bovine lactoferrin, to induce apoptosis in THP-l human monocytic leukemic cells using synthetic peptides. A synthetic peptide (Lfc-17/29, amino acid sequence; FKCRRWQWRMKKL) which is consist of 13 amino acids near the N-terminus of Lfcin-B induced cell death in THP-1 cells in a dose-dependent manner, showing apparent apoptotic changes such as hypodiploid forms of genomic DNA and apoptotic DNA fragmentation. (omitted)