• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.429-436
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• 2016

In this study, the genetic algorithm based optimal structural design method is proposed. The objective functions are to minimize the cost and $CO_2$ emissions, simultaneously. The cost and $CO_2$ emissions are calculated based on the cross-sectional dimensions, length, material strength, and reinforcement ratio of beam and column members. Thus, the cost and $CO_2$ emissions are evaluated by using the amounts of concrete and reinforcement used to construct a building. In this study, the cost and $CO_2$ emissions calculated at the phases of material transportation, construction, and building operation are excluded. The constraint conditions on the strength of beam and column members and the inter-story drift ratio are considered. The linear static analysis by using OpenSees is automatically conducted in the proposed method. The genetic algorithm is employed to solve the formulated problem. The proposed method is validated by applying it to the 4-story reinforced concrete moment frame example.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.26.3-27
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• 2009

한 기의 영상레이더 위성을 이용하여 동일한 촬영지역에 대해 적절한 기선벡터(Baseline)을 유지하는 두 장(scene)의 영상을 획득하여 그 지역의 정밀 표고차를 추출하는 레이더 간섭계(Interferometry) 임무를 수행하기 위해서는 반복지상궤적을 유지하도록 위성의 궤도를 주기적으로 조정해 주어야 한다. 이 연구에서는 반복지상궤적 유지 정밀도를 극대화시키기 위하여 최적의 기준궤도를 생성하고 이를 유지하기 위한 속도증분 및 궤도 조정 일정을 산출할 수 있는 궤도최적화 S/W 를 개발하였다. 이 연구의 최적 궤도 설계 문제는 다음과 같다. "시작시간 $T_0$에서 초기 접촉궤도 상태벡터 (ECEF 위치 및 속도벡터) $x_0$이고, 지상궤적반복주기 p 이후의 시간 $T_0+p$에서도 초기 접촉궤도 상태벡터와 동일한$x_0$가 되도록 궤도를 유지하려고 할 때, 여명 궤도(dawn-dusk and sun-synchronous orbit)에서 운영되는 위성의 연료소모(또는 속도증분)를 최소화시키는 가상의 궤도조정(maneuver) 횟수, 시기, 크기를 찾아라." 이 연구에서는 궤도최적화 문제를 풀기 위하여 GRACE 중력모델(GGM02C)이 적용된 수치적 방법의 위성궤도예측 알고리즘을 시스템 설계에 적용하였고, 매개변수 최적화 방법 중 구속조건이 있는 비선형 최적화 기법의 하나인 연속 2차 계획법(sequential quadratic programming)을 사용하여 해를 구하였다. 개발된 궤도최적화 S/W의 성능을 분석하기 위하여 고도 550km의 여명궤도를 돌며 지상궤적반복주기가 28일인 영상레이더 위성에 대해 적용하였다. 해석 결과를 통해, 비록 시스템의 비선형이 큼에도 불구하고 최소의 속도증분으로 정밀한 반복지상궤적이 유지됨을 알 수 있었다.

• Journal of Digital Convergence
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• v.10 no.7
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• pp.141-152
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• 2012

The typical evacuation guidance system based on fire detectors, which is being widely used in theaters and large buildings, is often operated in an analog manner. In case of fire, it often causes the system to lose a wired line or wireless fire detection sensor, resulting in the difficulty of transmitting signals from a wired or wireless fire detection sensor to the main fire monitoring device. Accordingly, this paper has proposed the broadcasting system for disaster management, having an efficient evacuation guidance plan when a disaster occurs. The system reacts to an emergency situation along with fire alarm sirens in real time. We have implemented the above system by means of a simulation program that prints the evacuation guidance information (e.g., location and time of fire, and evacuation path) on an LCD located in a building through the fire sensor network in case of an emergency (e.g., actual fire). We have developed the simulation system by using mathematical algorithms, such as the optimal path search and the fire smoke diffusion algorithm. This simulation program considers the structure of a building and the location where the fire has initially occurred, applying it to the simulator.

• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.803-813
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• 2017

Recently, various studies have been conducted to optimize the pump operation scheduling and/or the pump/tank size minimizing the system cost of water distribution network. Prior to that, it is important to understand the sensitivity of pump/tank size on the system cost and overall water quality. Here, we have performed the sensitivity analysis to investigate the effect of pump/tank size on the economic cost (construction and operation) and water quality (water age). The analysis was applied on a real, large-scale water transmission network currently operating in South Korea. The results revealed that the pump/tank size has a strong influence on system construction/operation costs. Especially, the tank size has a significant effect on the system-wide water quality. In the case of applied networks, the operating cost decreases as the capacity of the facility increases, but the design cost increases. Using a sensitivity analysis, a suitable range of pump/tank size could be suggested to minimize costs and stabilize the water quality at the same time prior to a system design.

• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.320-332
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• 2013

The feed air to MSW incinerator influences on the residence time of combustion gas, removal of unburnt ash and exiting gas temperature. Thus the secondary air volume could present sufficient residence time which can maintain the exiting temperature over $850^{\circ}C$. The secondary air also relates directly with the turbulence in the inside of combustion chamber, which finally provide the stable combustion condition. The present study designed a modern incinerator for a field scale, and evaluation of the potential amount of primary air based on the daily combustible quantity. From the evaluated primary air volume, the secondary air flow rate could be estimated, and its dynamic behavior was verified. In addition, the obtained air volume enables to find an optimum operation condition of the combustion. As a result of the CFD simulation, the air ratio 75 : 25 between primary and secondary air amount was optimum ratio than design criteria 72 : 28. And the flow velocity ratio of front-back of secondary air jet nozzle was found excellent at 1 : 3. In addition, the result of applied to the plant, the removal efficiency of NOx and CO generation would concentration of CO.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.95-106
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• 2012

The railway service in the Seoul metropolitan area is facing variety of l changes such as extension of service coverage, new construction, and introduction of express service which in turn causes changes on demands. The demand affects train operation characteristics (frequency of service, train formation) as well as on the congestion rate which is one of the major evaluation index in metropolitan area user service. For the efficient operation of the train, the relationship among the minimization of fleet number, operating cost, and service level has been analyzed. Using the Powersim, which is a system dynamics (System Dynamics) simulation program for realizing optimized simulation for train-formation, this paper identified that some stations of Gyeong-bu line exceeded limit congestion rate(150%) of a fleet already that means it is best to maintain current condition of the line; however, the Gyeong-in line and the Gwa-chon line showed no excess of the limit congestion rate so that it is possible to reduce 2-4 fleets of train for efficient operation. In addition, in case of Jang-hang line between Cheon-an and Sin-chang, a train consisting of 10 fleets provides services which is same formation of train for Gyeong-bu line. This study proved that the congestion rate will not rise greatly with only 4 fleets of a train for the service in Jang-hang line, and it is considered that a study for shuttle service between Cheon-an and Sin-chang is necessary.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.457-458
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• 2016

최근 계통연계가 어려운 도서산간지역의 전력문제 해결방안으로 마이크로그리드가 해법으로 제시되고 있다. 신재생에너지 및 디젤발전으로 구성되는 마이크로그리드는 신재생자원의 간헐적인 출력 때문에 적정규모를 선정하는데 어려움이 있다. 본 논문에서는 신재생 에너지의 간헐적인 출력을 고려하여 HOMER프로그램을 이용하여 적정 규모를 선정하고 감도 분석을 통하여 최적점을 설계하고 실제로 운영되는 마이크로 그리드와 비교하여 한계점을 파악하고 이를 토대로 개선하는 방향으로 연구를 진행한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.822-826
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• 2010

홍수피해저감 대책의 우선순위 결정은 시스템 차원에서 접근해야 한다. 홍수피해저감 사업을 분야별로 분리하여 분석하면 숲을 보지 못하고 산을 판단하는 오류를 범할 수 있다. 홍수피해 최소화를 위한 여러 전문 분야별 대안 분석도 중요하지만, 시스템 차원에서 홍수피해 저감 방안을 파악하고 대책을 수립해야 한다. 따라서 본 시스템의 개발 목적은 최적의 홍수피해저감 대책을 결정하는 데 있어 각각의 개별 정보를 공유하고, 의사결정 지원에 필요한 시스템을 구축하는 데 있다. 본 연구에서 제시한 홍수방어 대책 통합평가시스템은 수문학적 홍수분석 모형을 비롯하여 수리학적 홍수분석 모형, 의사결정지원 시스템이 통합되어 단일 시스템으로 구축되며 이를 위해서는 구체적인 사용자 요구파악과 관련 업무 프로세스 분석을 통한 전체적인 시스템 구조 설계가 중요하다. 홍수방어 대책 통합평가시스템의 핵심 요소는 1) GIS입력 모듈, 2) Fuzzy 알고리즘 모듈, 3) MCDA 알고리즘 모듈, 4) 결과표출 모듈 등 네 가지이다. 여기서 첫 번째 모듈은 GIS 입력 모듈로써 최적 방안 도출을 위한 빈도별 홍수터, 홍수심, 토지이용도 등과 같은 일련의 GIS 기초자료를 제공한다. 두 번째 단계는 퍼지화된 MCDA 모듈을 수행하기 위한 퍼지 알고리즘 및 퍼지 연산을 위한 내부 코딩이 이루어지는 단계로써 사용자 요구 사항에 따른 연산이 가능하다. 세 번째 단계는 최적 방안을 모색하는 MCDA 알고리즘과 연산 수행을 위한 세부 모듈로 구성됐다. 마지막 네 번째 단계는 모형과 DB간의 연계절차로써 사용자가 직접 운영하는 GUI 부분으로써 사용자의 요구 사항을 비롯하여 모형의 특징을 Matlab 프로그램으로 각각의 화면을 디자인한다. 이 단계에서는 모형을 수행하기 위한 DB가 구축되며 사용자의 요구에 의한 맞춤형 분석이 가능하도록 구성됐다. 통합시스템을 통한 의사결정과정의 합리성은 선택된 최적의 홍수저감대책의 사회 경제적 수용성은 물론 의사결정과정의 투명성을 높일 수 있을 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1389-1398
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• 2009

This research suggests the calculation and analytic method of determining the proper numbers of manual workers with simulation and DEA methods. For this, first of all we designed and analysed the simulation model of real facility being built in Dea-Jun. Secondly, we find the solution with DEA among various alternatives built based on the results of the simulation analysis. In the simulation process, the waiting time, the number of painted trains, and utilization of main equipment are considered as main response variables. After simulation, we built DMUs(Decision Making Unit) consisting of combined results with the manpower assignment policies, the numbers of workers, and the rate of skilled operators, and calculated the efficiency of DMUs with the DEA method. Among 27 DMUs, 4 DMUs turned out efficient technically and on scale. In conclusion, through the suggested procedure, this research shows the way that decision makers can solve the problems with various factors they should concern, along the scientific process, when building a new facility.

• Journal of the Korean GEO-environmental Society
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• v.25 no.6
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• pp.5-12
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• 2024

Currently, a grouting method that minimizes damage to the reservoir embankment by injecting solidification agent at low pressure is commonly used to ensure waterproofing and safety of the embankment, but the use of solidification agents can cause issues, such as a decrease in durability and a lack of clear method for determining the mixing ratio. In this study, when the base ground and solidification agent were stirred and mixed at various weight mixing ratios, the permeability coefficient and strength of the mixture were confirmed through laboratory tests, and the optimal mixing ratio was suggested through analysis of the test results. The specimen for the laboratory test was produced considering the mixing ratio of the solidification agent. The specimen for the permeability coefficient test was tested by producing one each of cohesionless and cohesive soil for a mixing amount of 1.5 kN/m³ of solidification agent, and the permeability test results confirmed that the water barrier performance was secured below the permeability coefficient value required by various design criteria. A total of 24 specimens for the strength test were produced, 3 for each of 5 mixing amounts for cohesive soil and 3 mixing amounts for cohesionless soil. The strength test results showed that the uniaxial compressive strength tends to increase linearly with increasing curing time for both cohesionless soil and cohesive soil when the mixing amount is less than 2.0 kN/m³. Therefore, the optimal mixing ratio applied to the site is determined to be mixing amount of 1.5 kN/m³ and 2.0 kN/m³. Finally, numerical analysis reflecting test results was conducted on design case for improvement projects for aging reservoirs embankment to verify the water barrier performance and safety improvement effects.