• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.87-92
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• 2013

Microalgae have been suggested as a promising feedstock for producing biofuel because of their potential of lipid production. In this study, a first principles ODE model for microalgae growth and neutral lipid synthesis proposed by Surisetty et al. (2010) is investigated for the purpose of maximizing the rate of microalgae growth and the amount of neutral lipid. The model has 6 states and 12 parameters and follows the assumption of Droop model which explains the growth as a two-step phenomenon; the uptake of nutrients is first occurred in the cell, and then use of intra-cellular nutrient to support cells growth. In this study, optimal input design using D-optimality criterion is performed to compute the system input profile and sensitivity analysis is also performed to determine which parameters have a negligible effect on the model predictions. Furthermore, model predictive control based on successive linearization is implemented to maximize the amount of neutral lipid contents.

• Journal of the Korea Convergence Society
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• v.13 no.5
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• pp.145-154
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• 2022

The purpose of this study is to investigate the difference in advertising effect of visual rhetoric type of Facebook ads depending on the user sensitivity and level of empathy. The experiment was designed as a between-subjects factorial design (visual rhetoric type) × 2 (brand sensitivity) × 2 (level of empathic understanding). The results of the experiment performed to analyze the strategies of Facebook ads for ads effectiveness can be summarized as follows: a three-way interaction effect for persuasive effects was found among the type of visual rhetoric, brand sensitivity, and empathic understanding for both types of visual rhetoric. Breaking down it by type of rhetoric, no interacting effect was observed between brand sensitivity and empathic understanding levels for the visual simile ads in most of the dependent variables. For the visual metaphor ads, however, the brand sensitivity and empathic understanding levels were found to have interaction effect in all dependent variables.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.6
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• pp.596-604
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• 2010

In order to investigate the operating conditions and major design parameters of a dual ramjet propulsion system, an theoretical analysis of ramjet and scramjet propulsion systems was performed. The performance characteristics of each engine are delivered by thermo-dynamical cycle analysis, considering loss effects in a real engine. The performance sensitivity analysis is conducted by investigating various performance parameters, such as an intake efficiency, combustor inlet Mach number, configuration of the combustor, fuel flow rate, and exhaust nozzle efficiency. Based on these analysis results, the processes of application to dual ramjet cycle engines are specified.

• Computational Structural Engineering
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• v.8 no.4
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• pp.99-106
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• 1995

The General conceptual constitution of structural optimization is formulated and the algorithm using the gradient projection method and design sensitivity analysis is discussed. Examples of minimum-weight design for six-story steel plane frame are taken to illustrate the applicability of this algorithm. The advantages of this algorithm such as marginal cost and design sensitivity analysis as well as system analysis are explained.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.209-214
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• 2018

In this paper, the techno-economic analysis of glycerol steam reforming for $H_2$ production capacity of $300m^3\;h^{-1}$ was carried out. The process of glycerol steam reforming was constructed by using Aspen $HYSYS^{(R)}$, a commercial process simulator, and parametric studies for the effect of the operating temperature on $H_2$ production was performed. Moreover, the economic analysis was conducted through an itemized cost estimation, sensitivity analysis (SA) and cash flow diagram (CFD), and the unit $H_2$ production cost was 5.10 $ ${kgH_2}^{-1}$ through the itemized cost estimation of glycerol steam reforming for $H_2$ production capacity of $300m^3\;h^{-1}$. SA was employed to identify key economic factors and various economic indicators such as net present value (NPV), discounted payback period (DPBP), and present value ratio (PVR) were found according to $H_2$ selling price using CFD.

• The Journal of Information Technology and Database
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• v.4 no.2
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• pp.105-119
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• 1998

최근에 이르러 정보 통신에 대한 수요가 폭발하고 있으나, 데이터 통신을 위한 네트워크를 구축하는 데는 막대한 비용이 소요되며, 장기적인 투자의 관점에서 효율성을 달성하기가 쉽지 않다. 본 연구는 기존의 네트워크를 확장해나가거나 새로운 네트워크를 구축하고자 할 때, 미래의 수요 및 신기술의 변화 등을 고려하여 최적의 네트워크를 설계하는 문제를 다루고 있다. 본 연구는 데이터 통한 네트워크의 장기적인 확장계획 수립의 문제를 분석적으로 다룬 최초의 논문이라고 할 수 있는 Dutta & Lim[4]의 기존 연구를 근간으로 하되 라우팅방법을 바꾸어 라우팅에 따른 해의 민감도를 분석함으로써, 네트워크의 설계 및 확장계획 수립을 위한 효율적인 해를 찾아내는 알고리즘을 개발하고자 하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.15-25
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• 1993

In order to promote the efficient use of composite materials, effort is currently being directed at the development of design criteria for composite structures. Insofar as design against buckling is concerned, it is well known that, for metal shells, a key step is the definition of 'knockdown' factors on the elastic critical buckling stress accounting mainly for the influence of initial geometric imperfections. At present, the imperfection sensitivity of composite shells has not been explored in detail. Due to the large number of parameters influencing buckling response (considerably larger than for isotropic shells), a very large number of tests would be needed to quantify imperfection sensitivity experimentally. An alternative approach is to use validated numerical models for this task. Thus, the objective of this paper is to outline the underlying theory used in developing a composite shell element and to present results from a validation exercise and subsequently from a parametric study on axially loaded glass fibre-reinforced plastic (GFRP) curved panels using finite element modelling. Both eigenvalue and incremental analyses are performed, the latter including the effect of initial geometric imperfection shape and amplitude, and the results are used to estimate 'knockdown' factors for such panels.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.617-626
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• 2022

In Korea, annual precipitation and its variability have gradually increased since modern meteorological observations began, and the risk of disasters has also been increasing due to significant regional variations and recent abnormal climate conditions. Given that damage from storms and floods mainly occurs around rivers, it is crucial to determine the appropriate design frequency for river-related projects. This study examined existing design practices used to determine hydrological design frequencies and suggested a new method to determine appropriate design frequencies. The study collected available data pertaining to seven evaluation factors, specifically the basin areas, shape parameters, channel slopes, stream orders, backwater effect reaches, extreme rainfall frequencies, and urbanized flood inundation areasfor 413 local rivers in Chungcheongnam-do in Korea. The estimated weights for areas of extreme rainfall frequencies and urbanized flood inundation were found to be 18, having a great effect on determining the design frequency. Compared with the established design frequency in previous government reports, the estimated design frequency increased for 255 rivers and decreased for 158 rivers.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.489-490
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• 2008

본 고에서는 체내 심실신호를 농하여 신경학적 분석 및 다형성의 측면에서 심실세동이 일어나는 것을 예측하는 분석 알고리즘을 설계하였다. 신경학적 측면에서는 시계열 신호의 Peak to Peak Interval을 예측법과 0.15Hz를 기준으로 HRV 신호의 AR Burg 모델링을 통하여 고주파성과 저주파성을 나누어 교감신경과 부교감신경의 활동성 통한 신경학적 예측법을 제시하였으며 또한 체내 심실신호의 비선형적 특성을 고려한 Fractal Dimension을 생성시킴으로서 주기성의 특성과 다형성 통한 예측법을 제시하였다. 체내 심전도를 기반으로 Simulation 하였으며 각 분석별 조합을 통하여 최적의 예측 구조를 찾고자 하였다. 의학적 의미가 있는 민감도와 특이도를 판별하였으며 예측을 위한 수행시간을 실험하였다. 이를 통하여 자율신경 활성도와 다형성 판별을 조합한 방법이 심실세동 예측을 위한 민감도의 측면에서 가장 우수함을 나타내었고 시뮬레이션을 위만 시뮬레이터(Simulator) UI(User Interface)를 제시하였다.

• Electronics and Telecommunications Trends
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• v.5 no.4
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• pp.134-144
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• 1990

칩의 다품종소량생산 경향과 대규모화 영향에 비례하여, 칩 전체 설계공정 중에서 자동화문제에 가장 민감한 레이아웃 설계에 있어서도 복잡도 및 난이도가 증가하고 있다. 따라서 레이아웃 설계에서는 다루어야 할 대량의 설계 데이터를 고속, 효율적으로 관리 처리하기 위한 고도의 자동설계기법이 절실히 요구되고 있는 실정이다. 본고에서는 이러한 칩 개발과제를 배경으로 하여 먼저 VLSI의 레이아웃 설계의 개요를 고찰하고, 설계에 있어서의 주 문제인 배치 및 배선에 대한 기본적인 설계기법, 각기법의 차이점, 그리고 연구현황에 대하여 기술하고 있다.