• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.926-928
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• 1998

A fast optimization algorithm has been evolved from a simple two stage optimal power flow(OPF) algorithm for constrained power economic dispatch. In the proposed algorithm, we consider various constraints such as power balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the coupled LP based OPF method to an average gain of 53.13 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

• 대한토목학회논문집
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• 제29권4D호
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• pp.459-465
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• 2009

u-Transportation (u-T) 환경은 차세대의 ITS로 간주되는 미래형 교통서비스로서 어디에서나 적절한 교통서비스를 제공하는 신 교통공간을 의미한다. 그러한 환경의 기초연구로서 본 연구는 기존 ITS에서 교통량 산출 방법을 검토하고, u-T 자료 수집환경(u-TSN)의 자료수집형태를 시뮬레이션으로 구현하여 ITS의 교통량 산정 결과와의 차이점을 연구하였다. 그 결과, u-T에서 단속류의 교통류율이 ITS보다 3.58% 높게 나타났으며, 평가지표 MARE와 MAE 값이 각각 31.4%, 31.1% 낮게 나타나고, 평가지표 균등계수는 1.9% 높게 나타나 상대적으로 u-TSN의 교통자료 집계가 더 우수함을 알 수 있었다. 이는 상류부 링크의 특정지점 교통량을 고려하지 못한 기존 방법론에 비해, u-T에서의 링크 특성이 잘 반영된 링크의 대표치라는데 의의 또한 있는바, 설계시간계수 등의 설계분야, 운영 분야 등에 보다 적절한 교통류율의 제공이 가능할 것으로 판단된다.

• 대한기계학회논문집A
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• 제31권3호
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• pp.355-364
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• 2007

Multidisciplinary design optimization based on independent subspaces (MDOIS) is a simple and practical method that can be applied to the practical engineering MDO problems. However, the current version of MDOIS does not handle the common design variables. A new version of MDOIS is proposed and named as MDOIS/2006. It is a two-level MDO method while the original MDOIS is a single-level method. At first, system analysis is performed to solve the coupling in the analysis. If the termination criteria are not satisfied, each discipline solves its own design problem. Each discipline in the lower level solves the problem with common design variables while they are constrained by equality constraints. In the upper level, the common design variables of related disciplines are determined by using the optimum sensitivity of the objective function. To validate MDOIS/2006, mathematical problem and NASA test bed problem are solved. The results are compared with those from other MDO methods. Finally, MDOIS/2006 is applied to flow patterner design and shows that it can be successfully applied to the practical engineering MDO problem.

• 오토저널
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• 제11권1호
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• pp.20-30
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• 1989

The unsteady conjugate forced convection-conduction heat transfer from a plate fin is numerically studied. The external forced flow is steady but the temperature of the fin base is an exponential change with time. Therefore, the unsteady energy equations of the fluid and the fin are solved simultaneously under the conditions of equality in heat flux and temperature at the fluid-fin interface at every instant of time. Numerical results are given for various quantities of interest including the local heat transfer coefficient, the local heat flux, the total heat transfer rate and the temperature distribution of fin under the effects of the convection-conduction parameter and the ratio of thermal diffusivities. The results of the present numerical solution have been compared with those of the conventional fin theory.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1386-1396
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• 2017

In this paper, a new approach is proposed to select the optimal sitting and sizing of distributed solar photovoltaic generation (SPVG) in a radial electrical distribution systems (EDS) considering load/generation uncertainties. Here, distributed generations (DGs) allocation problem is modeled as optimization problem with network loss based objective function under various equality and inequality constrains in an uncertain environment. A boundary power flow is utilized to address the uncertainties in load/generation forecasts. This approach facilitates the consideration of random uncertainties in forecast having no statistical history. Uncertain solar irradiance is modeled by beta distribution function (BDF). The resulted optimization problem is solved by a new Dynamic Harmony Search Algorithm (DHSA). Dynamic band width (DBW) based DHSA is proposed to enhance the search space and dynamically adjust the exploitation near the optimal solution. Proposed approach is demonstrated for two standard IEEE radial distribution systems under different scenarios.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.15-17
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• 2004

The flexible AC transmissions system (FACTS) is the underpinning concept upon which are based promising means to avoid effectively power flow bottlenecks and ways to extend the loadability of existing power transmission networks. This paper proposes a method by which the optimal locations of the FACTS to be installed in power system under cost function. The optimal solution of this type of problem requires large scale nonlinear optimisation techniques. We used Lagrange multipliers to solve a nonlinear equation with equality and ineaquality constraints. Case studies on the standard IEEE 14 bus system show that the method can be implemented successfully and that it is effective for determining the optimal location of the FACTS

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.541-544
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• 2004

The purpose of this study is to examine the antibiotic and physical properties of antibiotic concrete added inorganic liquor-type antibiotic agent(as named for Antibio-C) as the basic data for the development of antibiotic concrete. The main experimental variables were the types of antibiotic agents and it is tested for the properties of antibiotic, flow, compressive strength, crack-resistance and durability of concrete. As results, concrete containing antibiotic agent presented the strong antibiotic activities compared with non-added concrete. Also antibiotic concrete showed the higher or equality properties than non-added concrete with respect to compressive strength, crack resistance and durability such as neutralization depth.

• 대한전기학회논문지
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• 제33권10호
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• pp.410-422
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• 1984

This paper presents a new practical method for optimal active and reactive power control for the economic operation in electrical power system, and the programs are developed for digital computer solution. The major features and techniques of this paper are as follows: 1) The method is presented for finding the equivalent active power balance equation applying the sparse Jacobian matrix of power flow equation instead of using B constant as active power balance equation considering transmission loss, and thus for determining directly optimal active power allocation berween generator unitw satisfying the equality and inequality constraints. 2) The method is proposed for solving directly the optimum economim dispatch problem without using gradient method and penalty function for both active and reactive power control. As a result, the computing time are reduced and convergence characteristic is remarkably improved. 3) Unlike most of conventional methods which adopt the transmission loss as a objective function for reactive power control, the total fuel cost of themal power plant is adopted as objective function for both active and reactive power control. consequently, more reasonable and economic profit can be achieved.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2003년도 Annual Meeting of KSAP : International Symposium on Pharmaceutical and Biomedical Sciences on Obesity
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• pp.108-108
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• 2003

The current study was performed to observe the effects of Panax ginseng (PG) and P. quinquefolia (PQ) on hemodynamics such as blood flow rate (BF), blood flow velocity (BV), heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP, and body temperature (BT) in healthy young men. After testing equality of variance, Student's t-test using PROC TTEST was examined to. prove statistical differences between control and ginseng conditions at each time point. It was found that the BF data were fluctuated by personal deviation. In order to minimize the deviation, the results obtained for 6 hrs were reconstituted after dividing them into two periods of the first half from 1 to 3 hrs and of the latter half from 3.5 to 6 hrs. And then the reconstitution data and dose-response curves were obtained. Blood flow such as BF and BV shows significant increases both two periods in the dose of PG 2.25 and PG 9.0, whereas significant decrease in the dose of PG 4.5. However, in the PQ groups, the middle dose PQ 4.5 shows the highest significant increase among the three doses. Except for PG 2.25 in HR, other doses show significant decreases both in the first half and latter half. SBP of PQ 9.0 shows only a significant decrease in the first half; on the other hand, in the latter half, PG 4.5, PG 9.0 and PQ 9.0 significantly increase SBP. In addition, DBP of PG 2.25 and PG 4.5 show significant increase in the both periods. In the BT, PQ groups show gradual decrease from PQ 2.25 to PQ 9.0; however, PG groups show differently. PG 4.5 shows significant decrease, but PG 9.0 shows a increase without statistical meanings. In summary, PG is more effective in respect to keeping homeostasis of hemodynamics.

• Advances in Energy Research
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• 제4권4호
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• pp.255-274
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• 2016

This paper presents a novel symbiotic organisms search (SOS) algorithm to optimize both real power loss (RPL) and voltage stability limit (VSL) of a transmission network by controlling the variables such as unified power flow controller (UPFC) location, UPFC series injected voltage magnitude and phase angle and transformer taps simultaneously. Mathematically, this issue can be formulated as nonlinear equality and inequality constrained multi objective, multi variable optimization problem with a fitness function integrating both RPL and VSL. The symbiotic organisms search (SOS) algorithm is a nature inspired optimization method based on the biological interactions between the organisms in ecosystem. The advantage of SOS algorithm is that it requires a few control parameters compared to other meta-heuristic algorithms. The proposed SOS algorithm is applied for solving optimum control variables for both single objective and multi-objective optimization problems and tested on New England 39 bus test system. In the single objective optimization problem only RPL minimization is considered. The simulation results of the proposed algorithm have been compared with the results of the algorithms like interior point successive linear programming (IPSLP) and bacteria foraging algorithm (BFA) reported in the literature. The comparison results confirm the efficacy and superiority of the proposed method in optimizing both single and multi objective problems.