• Title/Summary/Keyword: 최적기준법

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Comparative Study of Approximate Optimization Techniques in CAE-Based Structural Design (구조 최적설계를 위한 다양한 근사 최적화기법의 적용 및 비교에 관한 연구)

  • Song, Chang-Yong;Lee, Jong-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.11
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    • pp.1603-1611
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    • 2010
  • The comparative study of regression-model-based approximate optimization techniques used in the strength design of an automotive knuckle component that will be under bump and brake loading conditions is carried out. The design problem is formulated such that the cross-sectional sizing variables are determined by minimizing the weight of the knuckle component that is subjected to stresses, deformations, and vibration frequency constraints. The techniques used in the comparative study are sequential approximate optimization (SAO), sequential two-point diagonal quadratic approximate optimization (STDQAO), and approximate optimization based on enhanced moving least squares method (MLSM), such as CF (constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization (PIDO) tools are utilized for the application of SAO and STDQAO. The enhanced MLSM-based approximate optimization techniques are newly developed to ensure constraint feasibility. The results of the approximate optimization techniques are compared with those of actual non-approximate optimization to evaluate their numerical performances.

The Model of Decision Making and the Method of Evaluating Criteria and Alternatives by Value Judgement, In Case of the University Student's Housing Choice (가치 판단에 기초한 의사결정 모형과 기준.대안의 평가 방법: 대학생의 주택 선택을 사례로)

  • Park, Kyu-Taeg;Lee, Sang-Yool
    • Journal of the Korean association of regional geographers
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    • v.9 no.2
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    • pp.135-152
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    • 2003
  • The purpose of this study is to suggest the model of supporting decision making and the method of evaluating criteria and alternatives by value judgement and to apply the model and method suggested to the case of the University Student's housing choice. The criteria and alternatives are evaluated in terms of intuitive judgement and the Analytic Hierarchy Process(AHP). The university students of the Daegu Metropolitan area consider the socioeconomic and environmental factors more important than the characteristics of housing to evaluate their future housing types. In terms of the student's intuitive judgement, socio-educational environment, accessibility, economy, natural environment, and the characteristics of housing are considered in order as an important criteria of evaluating housing. The orders of the important criteria done by an intuitive judgement and the AHP are different. In terms of the AHP, apartment, detached dwelling, and row house are preferred in order as the student's future housing types. The orders of preferred housing types are, however, dynamically changed based on specific criteria. In sum, the model of decision making and the method of evaluating criteria and alternatives by value judgement will be applied to the real problems defined by uncertainty and high risk.

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Application and Comparison of Direct Instrumentation Methods for Estimating Agricultural Water Intake (농업용수 취수량 산정을 위한 직접 계측방법 적용 및 비교)

  • Baek, Jong Seok;Kim, Chi Young;Cho, Sang Uk;Oh, Dong Heon;Song, Jaehyun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2021.06a
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    • pp.227-227
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    • 2021
  • 하천수의 효율적인 관리와 균형적인 물배분을 위해 신뢰도 있는 하천수 사용량 계측자료가 필수적이다. 공업·생활용수는 유량계를 설치하여 취수량에 대한 신뢰도 있는 자료를 홍수통제소에 보고하고 있으나, 농업용수는 유량계 설치 지점이 적고, 수문조작 등의 간접적인 계측방법 허용으로 취수량 자료의 신뢰도가 낮은 실정이다. 본 연구에서는 만경강 상류의 취수보를 대상으로 시험 유역 운영 및 검증을 통해 직접 계측방법의 취수량 산정 정확도를 비교하였다. 적용한 직접 계측방법은 초음파법, 전자파법, 수위-유량관계법으로 산정된 취수량 자료간의 절대오차 비교를 통해 정확도를 평가하였다. 점단위 취수량 자료 비교시, 현장측정값 대비 초음파법 5.86%, 전자파법 7.28%, 수위-유량관계법 11.84%의 오차가 발생하는 것으로 산정되어 초음파법이 가장 높은 정확도를 가지는 것으로 나타났고, 일단위, 월단위 자료 비교시 기준값으로 설정하였다. 일단위 취수량 자료 비교시, 초음파법으로 산정한 일평균 취수량 대비 전자파법 6.62%, 수위-유량관계법 8.62%의 오차가 발생하였다. 월단위 취수량 자료 비교시, 초음파법으로 산정한 월평균 취수량 대비 전자파법 5.81%, 수위-유량관계법 11.03%의 오차가 발생하였다. 산정된 취수량의 정확도는 초음파법, 전자파법, 수위-유량관계법 순이다. 고가의 첨단 계측장비를 적용하여 연속적인 유속 계측을 통해 산정한 취수량이 신뢰도가 높은 것으로 나타났다. 농업용수는 사용시설별 취수량 규모 편차가 크기 때문에, 추후 중요도가 높은 사용시설과 비교적 낮은 시설간의 구분을 통한 직접 계측방법의 최적 선정 후속연구가 필요하다.

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The Estimation of the Regional Gross Capital Stock in Transport Sector of Korea (교통부문의 지역별 자본스톡 추정)

  • 하헌구;조희덕
    • Journal of Korean Society of Transportation
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    • v.20 no.6
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    • pp.45-56
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    • 2002
  • In this research we estimated regional gross fixed capital stock of transport sector, such as road railroad, airport and seaport during 1968-1997 in Korea. We also compared our estimation results with those of Korea and Japan. As basic analytic method, we used the regional allocation method. To estimate regional gross fixed capital stock of transport sector, we used the basic data on national wealth surveys in 1997, regional land price index and regional facilities index in transport sectors. We used the most reasonable data in the process of estimation after reviewing the collected data In order to get the reasonable capital stock by regions. we chose the allocation index which can minimize the difference between the estimated result and the real regional capital stock in the process to allocate the total gross capital into the regions. Compared our results with those of other researches in Korea, estimates in our research project could be said more accurate than those.

Normalized Digital Surface Model Extraction and Slope Parameter Determination through Region Growing of UAV Data (무인항공기 데이터의 영역 확장법 적용을 통한 정규수치표면모델 추출 및 경사도 파라미터 설정)

  • Yeom, Junho;Lee, Wonhee;Kim, Taeheon;Han, Youkyung
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.37 no.6
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    • pp.499-506
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    • 2019
  • NDSM (Normalized Digital Surface Model) is key information for the detailed analysis of remote sensing data. Although NDSM can be simply obtained by subtracting a DTM (Digital Terrain Model) from a DSM (Digital Surface Model), in case of UAV (Unmanned Aerial Vehicle) data, it is difficult to get an accurate DTM due to high resolution characteristics of UAV data containing a large number of complex objects on the ground such as vegetation and urban structures. In this study, RGB-based UAV vegetation index, ExG (Excess Green) was used to extract initial seed points having low ExG values for region growing such that a DTM can be generated cost-effectively based on high resolution UAV data. For this process, local window analysis was applied to resolve the problem of erroneous seed point extraction from local low ExG points. Using the DSM values of seed points, region growing was applied to merge neighboring terrain pixels. Slope criteria were adopted for the region growing process and the seed points were determined as terrain points in case the size of segments is larger than 0.25 ㎡. Various slope criteria were tested to derive the optimized value for UAV data-based NDSM generation. Finally, the extracted terrain points were evaluated and interpolation was performed using the terrain points to generate an NDSM. The proposed method was applied to agricultural area in order to extract the above ground heights of crops and check feasibility of agricultural monitoring.

Development and validation of analytical methods for pyrifluquinazon residues determination on agricultural commodities by HPLC-UVD (HPLC-UVD를 이용한 농산물 중 pyrifluquinazon 잔류시험법 개발 및 검증)

  • Do, Jung-Ah;Kwon, Ji-Eun;Kim, Mi-Ra;Lee, Eun-Mi;Kuk, Ju-Hee;Cho, Yoon-Jae;Chang, Moon-Ik;Kwon, Kisung;Oh, Jae-Ho
    • Analytical Science and Technology
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    • v.26 no.3
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    • pp.174-181
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    • 2013
  • Pyrifluquinazon is classified with a quinazoline insecticide that regulates food intake by controling the feeding behavior acting on the endocrine or nervous system of pests such as aphids and white fly. To keep safety on pyrifluquinazon residues in agricultural commodities a simple, accurate and rapid analytical method was developed and validated using high performance liquid chromatograph (HPLC-UVD). The pyrifluquinazon residues acidified with 1% formic acid in samples were extracted with acetonitrile and partitioned with hexane subsequently to dichloromethane then purified with silica solid phase extraction (SPE) cartridge. The purified samples were detected using HPLC-UVD. The method was validated using apple and pear spiked with pyrifluquinazon at 0.02, 0.05 and 0.1 mg/kg and hulled rice, pepper, soybean at 0.05 and 0.1 mg/kg. Average recoveries were 70.5~107.9% with relative standard deviation less than 10%. The result of recoveries and overall coefficient of variation of a laboratory results in Gwangju regional FDA and Daejeon regional FDA was followed with Codex guideline (CODEX CAC/GL 40). This method is appropriated at pyrifluquinazon residues determination and will be used as official method of analysis.

An Exploratory Study on the Optimized Test Conditions of the Lock-in Thermography Technique (위상잠금 열화상 기법의 최적 실험 조건 탐색 연구)

  • Cho, Yong-Jin
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.2
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    • pp.157-164
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    • 2011
  • This work is devoted to the technique application of lock-in infrared Thermography in the shipbuilding and ocean engineering industry. For this purpose, an exploratory study to find the optimized test conditions is carried out by the design of experiments. It has been confirmed to be useful method that the phase contrast images were quantified by a reference image and weighted by defect hole size. Illuminated optical intensity of lower or medium strength give a good result for getting a phase contrast image. In order to get a good phase contrast image, lock-in frequency factors should be high in proportion to the illuminated optical intensity. The integration time of infrared camera should have been inversely proportional to the optical intensity. The other hand, the difference of specimen materials gave a slightly biased results not being discriminative reasoning.

Discrete Optimum Design of Semi-rigid Steel Frames Using Refined Plastic Hinge Analysis and Genetic Algorithm (개선소성힌지해석과 유전자 알고리즘을 이용한 반강접 강골조의 이산최적설계)

  • Lee, Mal Suk;Yun, Young Mook;Kang, Moon Myoung
    • Journal of Korean Society of Steel Construction
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    • v.16 no.2 s.69
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    • pp.201-213
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    • 2004
  • A GA-based optimum design algorithm and a program for plane steel frame structures with semi-rigid connections are presented. The algorithm is incorporated with the refined plastic hinge analysis method wherein geometric nonlinearity is considered by using the stability functions of beam-column members, and material nonlinearity, by using the gradual stiffness degradation model that includes the effects of residual stresses, moment redistribution through the occurrence of plastic hinges, semi-rigid connections, and geometric imperfection of members. In the genetic algorithm, the tournament selection method and micro-GAs are employed. The fitness function for the genetic algorithm is expressed as an unconstrained function composed of objective and penalty functions. The objective and penalty functions are expressed as the weight of steel frames and the constraint functions, respectively. In particular, the constraint functions fulfill the requirements of load-carrying capacity, serviceability, ductility, and construction workability. To verify the appropriateness of the present method, the optimal design results of two plane steel frames with rigid and semi-rigid connections are compared.

Development of Water Reuse System using Mixed Integer Programming (혼합정수계획법을 이용한 처리수 재이용 모형의 개발)

  • Chung, Gun-Hui;Kim, Joong-Hoon;Kim, Tae-Woong
    • Proceedings of the Korea Water Resources Association Conference
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    • 2009.05a
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    • pp.292-296
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    • 2009
  • 우리나라의 용수공급체계는 주로 여름에 집중된 강우를 댐이나 저수지에 저류하였다가 연중고르게 사용자들에게 공급하는 방법을 취하고 있다. 이때 도시지역의 생활용수는 갈수기에도 가장먼저 공급되어져야하는 우선순위를 가지는 반면, 농업용수는 가장 우선적으로 그 사용을 제한받는다. 하지만, 도시화로 인해 도시의 하수처리장 배출수량은 지속적으로 증가하고 있으며, 그 처리수의 대부분은 하천으로 방류되어 유실되고 있다. 방류수 수질기준에 맞추어 방류되는 처리수는 대량방류로 인해 자주 하천에 수질문제를 야기하기도 한다. 그러나 실제로 하수처리장의 처리수는 갈수기에 매우 유용하게 사용될 수 있는 수원 중 하나이다. 그러므로 그 처리수의 재이용에 관한 연구를 적절히 수행한다면, 갈수기에도 농업용수사용의 제한을 최소화할 수 있을 것이다. 그러므로 본 연구에서는 처리수 재이용 모형을 혼합정수계획법으로 개발하고, 하수처리장 처리수의 농업용수나 공공용수로의 사용을 제안하였다. 개발된 처리수 재이용 모형에서는 하천으로 방류되던 처리수를 농업용수나 공공용수로 재사용하는 시스템을 구축한다는 가정 하에, 그 공사비를 최소화하는 것을 목적으로 하였다. 또한 관말의 최소유지압력 등 수리학적인 제약조건을 만족시키도록 설계하였으며, 이 때문에 야기되는 비선형성을 선형화하여 계산시간이 짧은 동시에 전역해에 가까운 해를 찾을 수 있도록 하였다. 개발된 모형은 가상의 처리수 재이용 모형에 적용되어 시스템의 설계자에게 갈수기 용수공급의 최적 대안을 제시해 줄 수 있는 가능성을 보였다.

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A Study on Ventricular Fibrillation Prediction through neurologic and multi-morphic analyze of intra-cardiac database and Implementation of Simulator (체내 심전도 데이터의 신경학적 분석 및 다형성 판별을 통한 심실세동 예측에 관한 연구 및 시뮬레이터 구현)

  • Shin, K.S.;Kim, J.K.;Park, H.C.;Lee, C.K.;Lee, M.H.
    • 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.

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