본 논문에서는 AISC 표준 단면을 설계 변수로 하는 캔틸레버 타입 헬리데크 모델의 유전 알고리즘 최적설계를 소개한다. AISC 표준 단면을 단면 형상별로 분류하고 단면적 순으로 정렬한 후 정수 단면 번호를 부여하여 설계 변수로 최적설계를 수행하였다. 이 과정을 통하여 이산화된 설계 변수를 가지는 최적설계 문제를 해결하기 위해 유전 알고리즘을 적용하였다. 또한, 제약조건으로 허용응력 및 허용응력비 검사 조건을 모두 고려하여 구조물의 구조 안정성을 고려한 설계를 수행하였다. 최적설계 과정중 매 반복계산 마다 수행되는 구조해석 시간을 단축시키기 위해 선형 중첩법을 사용하였고, 이를 통해 구조 해석 시간을 약 75% 감소시킬 수 있었다. 또한 헬리데크 최적설계의 경량 효과를 높이기 위해 부재 그룹 세분화를 하였고, 그 결과를 선행 연구 모델, 기존의 부재 그룹 모델과 비교하였다. 그 결과 선행연구 대비 약 30톤의 부재를 절감할 수 있었으며, 구조적으로도 보다 안전한 헬리데크 설계를 얻을 수 있었다.

In this research, we evaluate on the disassemblability of recycling process for vehicle front door using the symbolic chart method and machine-learning algorithm. It is applied to the front door of 1600cc class vehicle, and then the conventional steel door and CFRP door were compared. Based on the principle symbolic chart method, the number of processes can be different according to decomposer proficiency of suitability of recycling process, so the evaluation method is required to supply this issue. The machine learning algorithm, and artificial intelligence method were applied and the applicable tools for each experiment were used to compensate the variations in the number of processes according to different proficiencies. Because CFRP front door has integrated components compare to steel door, so its disassemblability processes were decreased to 80 from 103 of the conventional steel door’s. It can be confirmed that the disassemblability was increased from the suitability of recycling equation. In case of the steel, disassemblability was approximately 60.6, in case of the CFRP is approximately 72 for car front door. Therefore, it can be concluded that the disassemblability of CFRP was better in the evaluation of suitability of recycling.

Self Organizing Map (SOM) is a neural network that is effective in classifying patterns that form the feature map by extracting characteristics of the input data. In this study, we propose an algorithm to determine the cell formation and the machine layout within the cell for the cell formation problem with operation sequence using the SOM. In the proposed algorithm, the output layer of the SOM is a one-dimensional structure, and the SOM is applied to the parts and the machine in two steps. The initial cell is formed when the formed clusters is grouped largely by the utilization of the machine within the cell. At this stage, machine cell are formed. The next step is to create a flow matrix of the all machine that calculates the frequency of consecutive forward movement for the machine. The machine layout order in each machine cell is determined based on this flow matrix so that the machine operation sequence is most reflected. The final step is to optimize the overall machine and parts to increase machine layout efficiency. As a result, the final cell is formed and the machine layout within the cell is determined. The proposed algorithm was tested on well-known cell formation problems with operation sequence shown in previous papers. The proposed algorithm has better performance than the other algorithms.

Triangulation is one of the fundamental problems in computational geometry and computer graphics community, and it has huge application areas such as 3D printing, computer-aided engineering, surface reconstruction, surface visualization, and so on. The Delaunay refinement algorithm is a well-known method to generate quality triangular meshes when point cloud and/or constrained edges are given in two- or three-dimensional space. In this paper, we propose a simple but efficient algorithm to triangulate Voronoi surfaces of Voronoi diagram of spheres in 3-dimensional Euclidean space. The proposed algorithm is based on the Ruppert’s Delaunay refinement algorithm, and we modified the algorithm to be applied to the triangulation of Voronoi surfaces in two ways. First, a new method to deciding the location of a newly added vertex on the surface in 3-dimensional space is proposed. Second, a new efficient but effective way of estimating approximation error between Voronoi surface and triangulation. Because the proposed algorithm generates a triangular mesh for Voronoi surfaces with guaranteed quality, users can control the level of quality of the resulting triangulation that their application problems require. We have implemented and tested the proposed algorithm for random non-intersecting spheres, and the experimental result shows the proposed algorithm produces quality triangulations on Voronoi surfaces satisfying the quality criterion.

This study focuses on the formation of input release lots in a semiconductor wafer fabrication facility. After the order-lot pegging process assigns lots in the fab to orders and calculates the required quantity of wafers for each product type to meet customers’ orders, the decisions on the formation of input release lots should be made to minimize the production costs of the release lots. Since the number of lots being processed in the wafer fab directly is related to the productivity of the wafer fab, the input lot formation is crucial process to reduce the production costs as well as to improve the efficiency of the wafer fab. Here, the input lot formation occurs before every shift begins in the semiconductor wafer fab. When input quantities (of wafers) for product types are given from results of the order-lot pegging process, lots to be released into the wafer fab should be formed satisfying the lot size requirements. Here, the production cost of a homogeneous lot of the same type of product is less than that of a heterogeneous lot that will be split into the number of lots according to their product types after passing the branch point during the wafer fabrication process. Also, more production cost occurs if a lot becomes more heterogeneous. We developed a multi-dimensional dynamic programming algorithm for the input lot formation problem and showed how to apply the algorithm to solve the problem optimally with an example problem instance. It is necessary to reduce the number of states at each stage in the DP algorithm for practical use. Also, we can apply the proposed DP algorithm together with lot release rules such as CONWIP and UNIFORM.

우리가 정보를 수집하고, 서로 상호작용하고, 우리의 정체성을 만들어 가는 방식은 점점 현재 인터넷상의 많은 사이트에서 사용되는 개인전용화 알고리듬에 의해 형성되고 있다. 개인전용화 알고리듬은 우리 자신의 관심사를 우리에게 공급해 줌으로서 각각의 개인에게 가장 연관되는 정보를 제공해 준다는 것이 개인전용화 알고리듬이 가진 문제이다. 이것이 만드는 피드백 루프는 개인의 정체성에 중요한 영향을 미칠 뿐 아니라, 개인과 집단 간의 관계에도 영향을 준다. 본 논문은 톰슨 앤 크레이그헤드(Thomson & Craighead), 라파엘 로자노-헤머(Rafael Lozano-Hemmer), 마닉스 드 나이스(Marnix de Nijs), 다니엘 로진(Daniel Rozin) 의 예술작품을 살펴보고 알고리듬 피드백 루프가 개인적, 집단적 행동, 자아에 대한 이미지와 세계관, 그리고 집단 정체성에 미치는 영향을 분석한다. 궁극적으로 본 논문은 순환적인 과정의 구조와 특성을 재구성함으로써 개발될 수 대안들을 모색하고자 한다.

Release planning in a software product line (SPL) is to select and assign the features of the multiple software products in the SPL in sequence of releases along a specified planning horizon satisfying the numerous constraints regarding technical prece- dence, conflicting priorities for features, and available resources. A greedy genetic algorithm is designed to solve the problems of release planning in SPL which is formulated as a precedence-constrained multiple 0-1 knapsack problem. To be guaranteed to obtain feasible solutions after the crossover and mutation operation, a greedy-like heuristic is developed as a repair operator and reflected into the genetic algorithm. The performance of the proposed solution methodology in this research is tested using a fractional factorial experimental design as well as compared with the performance of a genetic algorithm developed for the software release planning. The comparison shows that the solution approach proposed in this research yields better result than the genetic algorithm.

Release planning for incremental software development is to select and assign features in sequence of releases along a specified planning horizon. It includes the technical precedence inherent in the features, the conflicting priorities as determined by the representative stakeholders, and the balance between required and available resources. The complexity of this consideration is getting more complicated when planning releases in software product lines. The problem is formulated as a precedence-constrained multiple 0-1 knapsack problem. In this research a genetic algorithm is developed for solving the release planning problems in software product lines as well as tests for the proposed solution methodology are conducted using data generated randomly.

본 논문은 전국적인 소매업체의 각 지점별 고객 수요가 불확실한 상황에서 고객 서비스 목표 수준을 충족하는 최적 재고 수준을 결정하는 문제에 대해 연구하였다. 이를 위해 전국에 분포한 지점에서 물품을 판매하는 베스트바이, 월마트, 혹은 시어스와 같은 전국적인 소매업체 관점에서 사용할 수 있는 핵심 관리 지표(KPI)로서 ISR(In-Stock Ratio)를 정의하였으며, 전국적인 소매업체가 평균 ISR로 정의되는 고객 서비스 목표 수준을 충족하면서 각 지

수리가능 제품은 가격 비싸고 중요성이 크면서 새 제품을 구매하기 어려운 부품을 의미하며, 항공기 또는 선박의 엔진 등을 들 수 있다. 수리가능 제품에 대하여 고장이 발생할 경우 가용성을 유지하기 위하여 즉지 교체하여야 하고, 교체된 부품은 수리에 들어가야 한다. 이러한 문제에 대한 통제 시스템은 시스템의 효율성을 결정하는 중요한 요소이기 때문에, 다양한 시스템 구성에 대하여 많은 연구가 이루어져 왔다. 본 연구에서는 우선 중앙 수리기지와 여러 지역 수리

Finding the critical path (or the longest path) on acyclic directed graphs, which is well-known as PERT/CPM, the ambiguity of each acr’s length can be modeled as a range or an interval, in which the actual length of arc may realize. In this case, the min-

The Probabilistic Traveling Salesman Problem (PTSP) is an important topic in the study of traveling salesman problem and stochastic routing problem. The goal of PTSP is to find a priori tour visiting all customers with a minimum expected length, which sim

The Probabilistic Traveling Salesman Problem (PTSP) is an important topic in the study of traveling salesman problem and stochastic routing problem. The goal of PTSP is to find a priori tour visiting all customers with a minimum expected length, which simply skips customers not requiring a visit in the tour. There are many existing researches for the homogeneous version of the problem, where all customers have an identical visiting probability. Otherwise, the researches for the heterogeneous version of the problem are insufficient and most of them have focused on search base algorithms. In this paper, we propose a simple construction algorithm to solve the heterogeneous PTSP. The Minimum Expected Length Insertion (MELI) algorithm is a construction algorithm and consists of processes to decide a sequence of visiting customers by inserting the one, with the minimum expected length between two customers already in the sequence. Compared with optimal solutions, the MELI algorithm generates better solutions when the average probability is low and the customers have different visiting probabilities. We also suggest a local search method which improves the initial solution generated by the MELI algorithm.

Finding the critical path (or the longest path) on acyclic directed graphs, which is well-known as PERT/CPM, the ambiguity of each acr's length can be modeled as a range or an interval, in which the actual length of arc may realize. In this case, the min-max regret criterion, which is widely used in the decision making under uncertainty, can be applied to find the critical path minimizing the maximum regret in the worst case. Since the min-max regret critical path problem with the interval arc's lengths is known as NP-hard, this paper proposes a heuristic algorithm to diminish the maximum regret and the computational experiments shows the proposed algorithm contributes to the improvement of solution compared with the existing heuristic algorithms.

Finding the critical path (or the longest path) on acyclic directed graphs, which is well-known as PERT/CPM, the ambiguity of each acr's length can be modeled as a range or an interval, in which the actual length of arc may realize. In this case, the min-max regret criterion, which is widely used in the decision making under uncertainty, can be applied to find the critical path minimizing the maximum regret in the worst case. Since the min-max regret critical path problem with the interval arc's lengths is known as NP-hard, this paper proposes a heuristic algorithm to diminish the maximum regret and the computational experiments shows the proposed algorithm contributes to the improvement of solution compared with the existing heuristic algorithms.

Wireless LAN systems have been widely implemented for supporting the sireless internet services especially in the hotspot areas such as hospitals, homes, conference rooms, and so on. Compared with wired LAN systems, wireless LAN systems have the advantage

최근에 Active interaction control(AIC) 시스템이 준능동 제어 시스템의 하나로 제안되었다. AIC 시스템은 제어 대상 구조물과 보조 구조물로 구성되며, 두 구조물간의 실시간 결합-분리를 통해서 제어 대상 구조물을 제어하게 된다. 구조물간의 결합과 분리를 담당하는 장치의 실시간 변환은 스위칭 제어 알고리듬의 결합-분리 조건식에 의해 제어된다. 기존 스위칭 제어 알고리듬의 경우, 제어 대상 구조물의 응답을 효과적으로 감소시키는 반면 불필요하게 큰 제어력과 과도한 결합-분리 횟수를 필요로 하는 단점을 가지고 있다. 본 논문에서는 구조물간의 효율적인 결합-분리 조정을 위해서 스위칭 활성화 영역과 스위칭 비활성화 영역을 분리 표현하였으며, 결합-조건식에 의해 결정되는 스위칭 활성화 영역과 스위칭 비활성화 영역간의 일반적인 관계를 포괄 스위칭 틀을 이용하여 나타냈다. 과도한 결합-분리 횟수와 불필요하게 큰 제어력의 효과적인 감소를 위해서 새로운 스위칭 제어 알고리듬의 결합-분리 조건식은 포괄 스위칭 틀안에서 설계되었다. 또한 기존 논문에서 사용된 컨트롤 샘플링 주기(Control sampling period)의 역할을 결합-분리 횟수의 관점에서 재해석하였다. 제안된 알고리듬의 효용성과 컨트롤 샘플링 주기의 역할을 검증하기 위해서 단자유도 모델을 이용하여 자유진동에 대한 수치해석을 수행하였다. 수치해석결과, 총 스위칭 횟수를 감소시키기 위한 컨트롤 샘플링 주기의 인위적인 연장은 시스템의 제어 성능 향상에 필요한 구간 변환을 샘플링 주기 사이에서 억제시키는 단점을 가지고 있음을 확인하였다. 본 논문에서 제안된 알고리듬의 경우, 각각 과도한 결합-분리 횟수와 불필요하게 큰 제어력을 감소시키는데 효과적임을 알 수 있다.

Distribution centers in a distribution system that consists of the distribution centers and retailers supplies products to retailers. At the present, although total capacity of the distribution centers are enough to supply total demand of retailers, capac

확률적 외판원 문제(Probability Traveling Salesman Problem)는 일반적인 외판원 문제 (Traveling Salesman Problem)와 확률적 경로(Stochastic Routing) 문제에서 중요한 연구 분야 이다. 확률적 외판원 문제의 목적은 모든 고객을 방문하는 평균 거리가 최소가 되는 선험적 경로(priori tour)를 찾는 것이며, 경로에서 고객이 방문을 요구하지 않을 경우 다음 고객으로 방문을 하게 된다. 확률적 외판원 문제는 고객을 방문하는 확률에 따라 확률이 동일한 (homogeneous) 문제와 동일하지 않은 (heterogeneous) 이종 확률 문제로 분류되며, 대부분의 이종 확률 문제를 위한 연구는 탐색(search)기반 알고리듬을 고려하고 있다. 본 논문에서 제안된 최소 평균 거리 삽입 알고리듬은 탐색기반이 아닌 간단한 구성(construction) 알고리즘으로서 고객을 방문하는 순서를 결정하는 과정에서 이미 결정된 두 고객 사이에 평균거리(expected length)가 가장 작은 고객을 선택, 삽입하여 선험적 경로를 구한다. 제안된 알고리즘은 고객 방문 확률이 동일하지 않고 평균 확률이 낮은 경우 최적해에 근접한 해를 도출함이 실험을 통하여 관찰되었다.