• Ocean and Polar Research
• /
• v.39 no.4
• /
• pp.269-277
• /
• 2017

Medium compositions for the hyperthermophilic archaeon, Thermococcus onnurineus NA1 was statistically optimized to enhance formate-driven hydrogen ($H_2$) production by using response surface methodology. From the Plackett-Burman design-based experiment, it was confirmed that among the minor components of medium such as KCl, $MgSO_4$, $NH_4Cl$, Cystein-HCl, trace elements, Fe-EDTA and $CaCl_2$, the trace elements were screened as the only positively effective components with respect to $H_2$ production. Subsequently, the optimal concentrations of the trace elements and the major components of a medium such as NaCl, yeast extract and sodium formate were determined from the five-level central composite design (CCD)-based experiment. The resulting quadratic model predicted the maximum $H_2$ production of 46.6 mmol/L in serum bottle and it was validated experimentally using the optimal medium initially supplemented with 26.70 g/L of NaCl, 9.81 g/L of sodium formate, 3.50 g/L of yeast extract and 4.59 mL/L of trace elements. From the duplicate batch cultivations in the fermentor using the optimized medium, the a maximum $H_2$ production rate up to 71.8 mmol/L/h could be obtained, which was a 65% enhanced value compared with that obtained using the control medium, showing the high efficiency of the optimized medium.

• The Journal of the Acoustical Society of Korea
• /
• v.39 no.4
• /
• pp.227-236
• /
• 2020

This paper derives the insertion loss for the bubble layer of an air bubble curtain and an air masker which are used to reduce ocean anthropogenic noise such as the piling noise and the ship noise. The air bubble curtain is considered as a 'fluid-air bubble layer-fluid' model and the environment for the air masker is simplified as an 'vacuum-thin plate-fluid-air bubble layer-fluid' model. The air bubble layer in each model is assumed as the effective medium which has the complex wavenumber and the complex impedance corresponding to the bubble population distribution. The numerical simulations are performed to examine the insertion loss depending on the bubble population, the void fraction, and the thickness of the layer.

• Korean Journal of Organic Agriculture
• /
• v.26 no.2
• /
• pp.181-202
• /
• 2018

Most of eco-friendly agrifood processing enterprises in Korean rural area are small and medium-sized business. For this reason, it's hard for eco-friendly agrifood processing enterprises to neither analyze business performance for efficient business management nor establish their own business plan for rational decision-making. Therefore it's necessary to design effective mathematical programming model and to make practical application which can support rational management decision-making ensuring the stable business activity of eco-friendly agrifood processing enterprises. Accordingly this paper focuses on the designing and its application of multi-objective mathematical programming model using goal programming to support rational decision-making of eco-friendly agrifood processing enterprise. Hansalimanseongmachum Food Inc. which runs soy bean processing business making tofu based on regional-based soybean farms around Anseong City will be the specific case to apply multi-objective mathematical programming model in practice. And it will suggest measures to support rational management decision-making of other eco-friendly agrifood processing enterprises.

• Steel and Composite Structures
• /
• v.18 no.3
• /
• pp.711-737
• /
• 2015

Steel Plate Shear Walls (SPSWs) have been accepted widely as an effective lateral load resisting system. For seismic performance evaluation of a multi-story building with SPSWs, detailed finite element models or a strip model can be used to represent the SPSW components. However, such models often require significant effort for tall or medium height buildings. In order to simplify the analysis process, discrete elements for the framing members can be used. This paper presents development of a simplified equivalent braced model to study the behavior of the SPSWs. The proposed model is expected to facilitate a simplification to the structural modeling of large buildings with SPSWs in order to evaluate the seismic performance using regular structural analysis tools. It is observed that the proposed model can capture the global behavior of the structures quite accurately and potentially aid in the performance-based seismic design of SPSW buildings.

• Journal of Navigation and Port Research
• /
• v.38 no.6
• /
• pp.585-591
• /
• 2014

The primary objective of the current work is to predict speed performance of the medium patrol boat over $F_N=0.5$ employing experimental materials based on the CFD before model tests. In other words, the predicted brake powers according to ship speeds are assessed satisfying the main engine capacity. The subject ships are selected the two different stern hull forms. The flow computation are conducted considering free surface and dynamic trim using a commercial CFD code(STAR-CCM+). The resistances of the bare-hull are obtained from CFD. Wave patterns, pressures and limiting streamlines on the hull and velocity distribution in the propeller plane for the two hull forms are compared using CFD. The effective powers of the object ships are assessed based on CFD. Resistance increase according to the attached appendages and quasi-propulsive efficiency are employed the experimental datas. Speed performance prediction method concerning high speed vessels like a medium patrol boat is developed employing CFD and experimental data.

• (The) Korean Journal of Advertising
• /
• v.27 no.3
• /
• pp.113-139
• /
• 2016

The purpose of this study was to investigate perception of media characteristics inorder to provide a theoretical background for the media mix strategy. Considering the qualitative-vale of each medium, this study conducted a survey consisting of 60 academic and advertising industry experts to examine how they perceive and evaluate the characteristics of TV, radio, newspaper, OOH, Internet, mobile, and digital signage in terms of media effectiveness. The results, first, show that 'media engagement', 'effective reach', and 'behavioral targeting' are three most important indices to assess the media effectiveness. Second, the Internet was best evaluated in its various aspects according to the MAIX model, which gauges the effectiveness of each advertising medium. The study also proved that each advertising medium has unique advantages so that each medium should adopt a strategic positioning to differentiate it from other media. As such, this study provides meaningful evidences to understand the various characteristics and competitive value of advertising media and useful guidelines for media planning.

• Journal of Engineering Education Research
• /
• v.16 no.3
• /
• pp.10-19
• /
• 2013

Recently, Korean universities have increased the number of English Medium Instruction (EMI) lectures in order to allow students to gain both specialized knowledge and enhanced English ability. Previous researches on effective EMI lectures have focused on exploring the effects of learners' cognitive and affective characteristics on learning outcomes. Whereas the input variables of learning have been investigated as predicting variables of effects in EMI lectures, there has been a few research for investigating process variables to yield learning outcomes. The purpose of this study is to analyze the structural relationships among variables affecting on learner satisfaction and effects. The participants are 209 engineering students from various majors. Independent variables are defined as English motivation, English competency, and English confidence, a mediated variable is Cognitive engagement, and dependent variables are Learning satisfaction and Educational effect perception. The results show that the relationships are statistically significant: learners' English competency & English confidence ${\rightarrow}$ Cognitive engagement ${\rightarrow}$ Learning satisfaction ${\rightarrow}$ Educational effect perception. Especially, the structural model confirms that the effect of learners' English confidence on Learning satisfaction and Educational effect perception is mediated by the level of learners' Cognitive engagement. Further, the implication for effective EMI lectures is discussed based on the observed research results.

• Coupled systems mechanics
• /
• v.7 no.1
• /
• pp.43-59
• /
• 2018

The presence of the pore fluid strongly influences the reponse of the soil subjected to external loading and in many cases increases the risk of final failure. In this paper, we propose the use of a discrete beam lattice model with the aim to investigate the coupling effects of the solid and fluid phase on the response and failure mechanisms in the saturated soil. The discrete cohesive link lattice model used in this paper, is based on inelastic Timoshenko beam finite elements with enhanced kinematics in axial and transverse direction. The coupling equations for the soil-pore fluid interaction are derived from Terzaghi's principle of effective stresses, Biot's porous media theory and Darcy's law for fluid flow through porous media. The application of the model in soil mechanics is illustrated through several numerical simulations.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.513-518
• /
• 2006

An investigation of the transport properties of polysilicon TFTs, using sequential laterally solidified, SLS, material, is presented. This material has a location controlled distribution of grain boundaries, GBs, which makes it particularly useful for the analysis of their influence on the performance of polysilicon TFTs, and to address the issue of the role of spatially localised trapping states. The experimental results were analyzed by using numerical simulations, and the effective medium approximation was compared with a discrete grain model.

• Korean Management Science Review
• /
• v.26 no.3
• /
• pp.1-9
• /
• 2009

In this paper, we present mathematical models for the ring covering problems arising in the design of multi-ring WDM networks. Also, we present efficient algorithms to solve the suggested models. By the computational experiment, our model can solve the medium-sized networks efficiently and shows better performance than the existing heuristic method. Although we propose an efficient method for the column generation procedure, branching rule that does not destroy the column generation structure is unsolved. Further research is required to develop an effective branching rule.