• 한국지능시스템학회논문지
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• 제24권1호
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• pp.46-51
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• 2014

공학적 시스템 최적설계의 가장 중요한 과정은 설계변수와 시스템 응답과의 관계를 파악하는 것이다. 시스템 최적화의 경우 반응표면법이 주로 사용되고 있다. 반응표면법의 최적화 과정은 대표적인 후보대안을 이용하여 설계공간을 구성하고, 설정된 설계 공간에서 설계 최적점을 찾는다. 설계공간의 구성에 따라 최적점이 변화되므로 합리적인 최적점을 찾기 위해서는 설계공간의 구성이 매우 중요하다. 따라서 본 연구에서는 설계변수와 시스템응답의 관계를 신경반응표면을 이용하여 설계공간을 구성하고, 구성된 설계 공간 안에서 다목적유전자 알고리즘을 이용하여 최적 형상을 예측 할 수 있는 '신경반응표면을 이용한 공학 구조물 설계 프레임워크 구축'을 시도하였다. 구축된 프레임워크의 유용성을 확인하기 위해 비선형 수학함수 문제를 적용하였다. 구축된 프레임워크를 통해 공학문제의 최적화 과정에서 시간의 제약을 해결하고, 효과적인 최적설계가 가능함을 확인할 수 있었다. 향후에는 본 연구의 결과를 바탕으로 실제 조선해양공학 최적화 문제에 적용을 시도할 것이다.

• 디지털콘텐츠학회 논문지
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• 제3권1호
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• pp.113-122
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• 2002

반도체와 관련한 실리콘웨이퍼의 평탄도는 양질의 웨이퍼를 보증하는 가장 중요한 요소이다. 따라서 평탄도(flatness)를 측정하고 제어하는 Polishing이라는 공정은 웨이퍼 생산의 여러 라인중 특별히 중요시 되는 과정이며 현재 이 공정에서는 담당 엔지니어가 웨이퍼의 모형을 모니터에서 육안으로 관찰하여 판단하고 평탄도를 높이기 위한 제어를 하고 있다. 그러나 사람에 의한 것이므로 많은 경험이 필요하고 일일이 체크해야하는 번거로움이 있다. 본 연구는 이러한 비효율적인 작업의 효율화를 위해 이루어 졌으며 Polishing 공정에 있어 평탄도를 사람이 아닌 시스템에 의해 자동으로 측정하여 제어하는 알고리즘을 제안한다. 여기서 제안한 시스템은 보간 다항식을 이용하여 웨이퍼 전역의 두께를 추정하고 Polishing공정에서 평탄도를 높이기 위해 제어 가능한 모형별로 분류할 수 있도록 하였다.

• Journal of Computational Design and Engineering
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• 제1권3호
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• pp.187-193
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• 2014

One of the hottest challenges in automotive industry is related to weight reduction in sheet metal forming processes, in order to produce a high quality metal part with minimal material cost. Stamping is the most widely used sheet metal forming process; but its implementation comes with several fabrication flaws such as springback and failure. A global and simple approach to circumvent these unwanted process drawbacks consists in optimizing the initial blank shape with innovative methods. The aim of this paper is to introduce an efficient methodology to deal with complex, computationally expensive multicriteria optimization problems. Our approach is based on the combination of methods to capture the Pareto Front, approximate criteria (to save computational costs) and global optimizers. To illustrate the efficiency, we consider the stamping of an industrial workpiece as test-case. Our approach is applied to the springback and failure criteria. To optimize these two criteria, a global optimization algorithm was chosen. It is the Simulated Annealing algorithm hybridized with the Simultaneous Perturbation Stochastic Approximation in order to gain in time and in precision. The multicriteria problems amounts to the capture of the Pareto Front associated to the two criteria. Normal Boundary Intersection and Normalized Normal Constraint Method are considered for generating a set of Pareto-optimal solutions with the characteristic of uniform distribution of front points. The computational results are compared to those obtained with the well-known Non-dominated Sorting Genetic Algorithm II. The results show that our proposed approach is efficient to deal with the multicriteria shape optimization of highly non-linear mechanical systems.

• Smart Structures and Systems
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• 제26권5호
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• pp.559-573
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• 2020

One of the powerful data management tools is Building Information Modeling (BIM) which operates through obtaining, recalling, sharing, sorting and sorting data and supplying a digital environment of them. Employing SHM, a BIM in monitoring systems, would be an efficient method to address their data management problems and consequently optimize the economic aspects of buildings. The recording of SHM data is an effective way for engineers, facility managers and owners which make the BIM dynamic through the provision of updated information regarding the occurring state and health of different sections of the building. On the other hand, digital transformation is a continuous challenge in construction. In a cloud-based BIM platform, environmental and localization data are integrated which shape the Internet-of-Things (IoT) method. In order to improve work productivity, living comfort, and entertainment, the IoT has been growingly utilized in several products (such as wearables, smart homes). However, investigations confronting the integration of these two technologies (BIM and IoT) remain inadequate and solely focus upon the automatic transmission of sensor information to BIM models. Therefore, in this composition, the use of BIM based on SHM and IOT is reviewed and the economic application is considered.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권4호
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• pp.750-769
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• 2015

The geometry of engineering systems affects their performances. For this reason, the shape of engineering systems needs to be optimized in the initial design stage. However, engineering system design problems consist of multi-objective optimization and the performance analysis using commercial code or numerical analysis is generally time-consuming. To solve these problems, many engineers perform the optimization using the approximation model (response surface). The Response Surface Method (RSM) is generally used to predict the system performance in engineering research field, but RSM presents some prediction errors for highly nonlinear systems. The major objective of this research is to establish an optimal design method for multi-objective problems and confirm its applicability. The proposed process is composed of three parts: definition of geometry, generation of response surface, and optimization process. To reduce the time for performance analysis and minimize the prediction errors, the approximation model is generated using the Backpropagation Artificial Neural Network (BPANN) which is considered as Neuro-Response Surface Method (NRSM). The optimization is done for the generated response surface by non-dominated sorting genetic algorithm-II (NSGA-II). Through case studies of marine system and ship structure (substructure of floating offshore wind turbine considering hydrodynamics performances and bulk carrier bottom stiffened panels considering structure performance), we have confirmed the applicability of the proposed method for multi-objective side constraint optimization problems.

• 한국CDE학회논문집
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• 제16권5호
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• pp.344-350
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• 2011

In injection molding industries, CAE analyses are generally used to find out problems predicted during the process of manufacturing. The results of CAE analyses consist of much in formation such as meshes and stress, so that the size of data is pretty large. To reduce the size of the data and to make it easy to share, the CAE result to JT translator is proposed in this paper. The translator consists of three modules to translate CAE result to JT format; Extracting module gets ASCII data of product shape and the result values of CAE analysis. Sorting module and mapping module make an element data set and JT file with the data extracted from Extracting module respectively. To the JT files, engineers are able to append product properties and their comments, so that they can share the whole history of the analysis process. In addition, our case study shows that the size of JT format is reduced by almost 90% of its original data format.

• Journal of Biosystems Engineering
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• 제18권1호
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• pp.30-36
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• 1993

Cucumbers being living biological materials are generally vulnerable to external forces, especially, bending force during the processes, because they have usually longish shape. Understanding the mechanical and viscoelastic properties of cucumber is important to analyze various characteristics which might be helpful in determining design parameters for the processing equipment such as sorting, packaging and transporting machine. The objectives of this study were to determine ultimate bending strength, deflections, and hysteresis losses for the cucumbers from the bending tests. Within the range of loading rate from 20 to 100mm/min, the ultimate bending strength of the cucumber samples were 525-630kPa at the Gyeousalicheongjang and the Baekdadagi, and 476~618kPa at the Cheongjangmadi, respectively, but the ultimate bending deflection ratio of the Cheongjangmadi showed the highest value among the tested samples. The effect of loading rate on the physical properties of the cucumber was relatively significant, all considered physical properties and degree of elasticity of the cucumber increased with the loading rate, but the hysteresis loss decreased with it.

• 전자공학회논문지A
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• 제30A권3호
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• pp.130-138
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• 1993

A mechanism for collision detection in general animation system is necessary to prevent the interpenetration among multiple objects. On the other hand, a dynamic simulation system which is a part of animation system simulates realistic motions using dynamics after the collision, which is called collision response. In this paper, a method for reducing the CPU time for collision detection by removing redundant calculations and object sorting is proposed. A dynamic simulation system including collision detection and response function was implemented to demonstrate the proposed methods, where the input data as elasticity, friction, gravity, object shape, external force and external torque are given by the user. The system simulates motions of multiple objects using dynamics, and generates the wireframe display.

• 한국제4기학회지
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• 제7권1호
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• pp.27-39
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• 1993

전라남도 완도의 남단에 동-서 방향으로 발달되어 있는 정도리 자갈해빈 (shingle beach)은 전형적인 만입형 해빈 (pocket beach)에 속한다. 1992년 5월부터 1993년 3월까지 야외조사를 실시하여 폭풍이후의 해빈단면 변화를 관찰하고 자갈의 조직변수들 (textural parameters)을 계산하였다. 또한 해안선에 수직 및 수평한 방향으로의 자갈의 입도와 형태분포를 조사하여 해빈 전반에 걸친 퇴적물의 운반과정과 퇴적과정을 고찰하였다. 정도리 자갈해빈의 단면 (beach profile)은 크게 평상시에 조석과 파랑의 영향을 받는 보통대 (Fair-weather zone)와 폭풍 기상조건하에서 형성되는 폭풍대 (Storm-weather zone)로 구분된다. 각 부분 (zone)은 파랑의 swash, overwash 및 backwash의 연속적 퇴적시스템에 의한 일련의 해빈면 (beach face)과 범 (berm)으로 구성된다. 폭풍대는 다시 해빈면과 범을 하나의 단위로 하여 A-, B-, C-group으로 세분하였다. 해안선과 수직한 방향으로의 입도변화는 보통대의 경우 범의 자갈입도 (45.5 mm ~ 123.6 mm)가 해빈면의 것 (36.8 mm ~ 78.3 mm)보다 더 조립하여 모래해빈(sand beach)에서 나타나는 입도분포와 유사하게 나타났다. 그러나 폭풍대에서는 범의 자갈입도 (33.1 mm ~ 82.5 mm)가 해빈면의 자갈입도 (46.2 mm ~ 105.2 mm) 보다 더 세립한 양상을 보였다. 수직한 방향으로의 자갈형태 분포의 변화는 폭풍대의 C-group을 제외한 각 부분의 disc형태의 비율이 해빈면 (45.9 % ~ 51.3 %)보다 범(50.0 % ~ 58.5 %)에서 더 높게 나타났으며, equant형태의 비율은 전체적으로 바다쪽으로 가면서 10 % 정도 증가하는 양상을 보였다. 이와 같은 결과로 해안선에 수직한 방향으로 강한 파랑에너지에 의한 입자의 크기와 형태에 따른 분급작용이 이루어지고 있음을 알 수 있었다. 해안선에 평행한 방향으로의 자갈입도는 해빈의 동쪽 끝부분이 조립하게 나타나는것을 제외하고는 동-서 방향으로의 입도분포가 별다른 변화를 보이지 않았다. 그러나 동-서 방향으로의 자갈형태 분포는 뚜렷한 변화를 보여 해빈의 동쪽에서 서쪽으로 갈수록 disc와 blade형태가 각각 20 %와 13 %로 감소하고, equant형태는 34 % 정도 증가하는 경향을 보였다. 이로써 해안선에 평행한 방향으로는 자갈의 형태에 따른 분급작용이 우세하게 일어남을 알 수 있었다. 자갈의 형태를 입도별로 삼각도표에 나타낸 결과 입도가 작을수록 둥글거나 편장된 (elongate) 형태로의 방향성을 보이는 것으로 나타났다. 이러한 사실로 미루어 볼 때, 자갈의 형태는 일차적으로 모암의 암석성분에 의해 결정되나 운반된 이후에는 파랑의 작용을 끊임없이 받으면서 분급작용과 자갈의 크기에 따른 형태적 진화과정을 겪는 것으로 사료된다.

• 한국의류산업학회지
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• 제18권3호
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• pp.327-337
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• 2016

The purpose of this study is for size suitability and fitness improvement for Korean 20's women. This study has classified hip types of 20's women by the 6th Korean Anthropometric Survey(Size Korean), then compared their lower body-type by hip types each other. The results are as follows. Factor analysis in sorting hip types can be explained 77.72% by nine factors. And cluster analysis can be divided into three types. Type 1 is referred to as a general type which has the largest size in the 'Hip circumference', but the buttocks's horizontal sizes are in the middle size besides the hip line. Type 2 is referred to as a protruding type in upper buttocks which is large in protruding volume of upper buttocks, but the buttock's horizontal sizes are small including 'Hip circumference', and buttock's horizontal section form close to circle. Type 3 is referred to as a type which is contrary to Type 2. Type 3 is small in protruding volume of upper buttocks, but large in lower buttocks, and the protrusions in whole buttocks are small, so the side view of Type 3 made gentle fit shape. By these results, the study could classify lower body of 20's women, and it can be basic data for new sizing systems and pattern development of bottoms.