• 한국초전도ㆍ저온공학회논문지
• /
• 제4권1호
• /
• pp.114-118
• /
• 2002

We introduce a design technique for homogeneous magnets using evolution strategy. The method has several advantages over existing techniques including: it allows complete flexibility in geometric constraints on the shape of both the coil and the homogeneous volume; it guarantees a globally optimal solution, and it automatically searches the minimum number of coils that satisfies given constraints.

• 한국정밀공학회지
• /
• 제18권10호
• /
• pp.116-126
• /
• 2001

This paper suggests a numerical method to find optimal geometric path and minimum-time motion for a spatial 6-link manipulator arm (PUMA 560 type). To find a minimum-time motion, the optimal geometric paths minimizing 2 different dynamic performance indices are searched first, and the minimum-time motions are searched on these optimal paths. In the algorithm to find optimal geometric paths, the objective functions (performance indices) are selected to minimize joint velocities, actuator forces or the combinations of them as well as to avoid one static obstacle. In the minimum-time algorithm the traveling time is expressed by the power series including 21 terms. The coefficients of the series are obtained using nonlinear programming to minimize the total traveling time subject to the constraints of velocity-dependent actuator forces.

• 한국통신학회논문지
• /
• 제33권11A호
• /
• pp.1072-1078
• /
• 2008

이 논문에서는 전송 실효성 극대화를 위하여 사용자 별 최소 및 최대 전송률 제한을 두는 페이딩 방송채널에서 내림차순 전력할당에 기반한 효율적인 SCM (superposition coding multiplexing) 방법을 제안한다. 이 방법은 3단계로 구성되는데, 1단계에서는 전송 가능한 최대의 사용자 집합을 선정하고, 2단계에서는 사용자 별 송신전력의 내림차순으로 해당 사용자의 최소 전송률을 보장하는 최대 허용 간섭전력을 결정하는 방식으로 해당 사용자별 송신전력을 할당하고 잔여전력을 계산한다. 3단계에서는 2단계에서 잔여전력이 발생하는 경우에 수행하며, 내림차순 마지막 사용자부터 다시 오름차순으로 해당 사용자의 최대 전송률 제공에 필요한 전력 범위까지 최대로 추가 전력을 할당한다. 이 방법은 2단계 내림차순 할당에서 각 사용자가 자신의 최소 전송률 보장을 위하여 이후 사용자들로부터의 최대 허용 간섭전력을 고려하여 전력할당이 이루어졌으며 오름차순 추가 할당으로 인한 해당 사용자 이후 모든 순위 사용자들에 대한 전력 재할당을 필요로 하지 않는다. 따라서, 제안한 방법은 사용자 별 최소뿐만 아니라 최대 전송률 제한을 두는 경우, 특히 사용자 수가 많아질수록 계산이 더욱 효율적이다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권5호
• /
• pp.1569-1586
• /
• 2015

This paper considers the optimal cell association and resource allocation for load balancing in a heterogeneous cellular network subject to user's quality-of-service (QoS) constraints. We adopt the proportional fairness (PF) utility maximization formulation which also accommodates the QoS constraints in terms of minimum rate requirements. With equal resource allocation this joint optimization problem is either infeasible or requires relaxation that yields a solution which is difficult to implement. Nevertheless, we show that this joint optimization problem can be effectively solved without any priori assumption on resource allocation and yields a cell association scheme which enforces single BS association for each user. We re-formulated the joint optimization problem as a network-wide resource allocation problem with cardinality constraints. A reweighted heuristic l₁-norm regularization method is used to obtain a sparse solution to the re-formulated problem. The cell association scheme is then derived from the sparsity pattern of the solution, which guarantees a single BS association for each user. Compared with the previously proposed method based on equal resource allocation, the proposed framework results in a feasible cell association scheme and yields a robust solution on resource allocation that satisfies the QoS constraints. Our simulations illustrate the impact of user's minimum rate requirements on cell association and demonstrate that the proposed approach achieves load balancing and enforces single BS association for users.

• 대한산업공학회지
• /
• 제21권3호
• /
• pp.313-327
• /
• 1995

This paper deals with ordering policies for a multi-echelon distribution system. The system we are concerned consists of one Central Distribution Center(CDC) and N nonidentical Regional Distribution Centers(RDCs) which have different demand rates, minimum filtrates, leadtimes, etc. We develop an algorithm for determining the optimal ordering policies of the CDC and the RDCs under the constraints of minimum filtrates of RDCs and maximum allowable delay of CDC.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
• /
• pp.445-449
• /
• 1989

Achievement of a straight line motion in the Cartesian space has a matter of great importance. Minimization of task execution time with linear interpolation in the joint space, accomplishing of a approximation of straight line motion in the Cartesian coordinate is considered as the prespecified task. Such determination yields minimum time joint-trajectory subject to input torque constraints. The applications of these results for joint-trajectory planning of a two-link manipulator with revolute joints are demonstrated by computer simulations.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
• /
• pp.75-78
• /
• 2000

This paper presents a new algorithm for allocating the data path to achieve the minimum power consumption under the constraints of minimum hardware resources. In order to minimize the power consumption, the proposed algorithm tries to minimize the input transitions of functional units, unnecessary computations, and size of interconnects in a greedy manner during a]location. Experimental results using benchmarks indicate the proposed algorithm achieves 17.5% power reduction on average, when compared with the genesis-lp［1］high-level synthesis system.

• 한국항해학회지
• /
• 제13권2호
• /
• pp.75-95
• /
• 1989

The study presents the optimum design of B/C midship structure based on the classification society's Rule. The SUMT (Sequential Unconstrained Minimization Technique), using the Direct Search Methods (Hooke and Jeeves, Simplex) is applied to the solution of this nonlinear optimum design problem with constraints. Through the optimum designs of existing ships(60k, 186k, 220k), the amount 0.45-6.18% in weight of their midship structures are obtained on the viewpoint of minimum weight design.

• 한국통신학회:학술대회논문집
• /
• 한국통신학회 1983년도 추계학술발표회논문집
• /
• pp.108-111
• /
• 1983

This paper presents a new method for the optimum capacity assignment in store-and-forward communication networks under a total fixed-capacity constraints. Any two link capacities needed in this method can have the desirable quantites and then other capacities can be obtained from the fixed two link capacities. When the minimum and the maximum capacities that are the quantites of the conventional method are fixed, the total average time delay from the new method is almost the same as that from the conventional method. And when the minimum capacity is fixed, the new method gives smaller average time delay.

• Structural Engineering and Mechanics
• /
• 제58권3호
• /
• pp.597-612
• /
• 2016

This paper presents an optimization process using Harmony Search Algorithm for minimum weight of steel space frames under earthquake effects according to Turkish Earthquake Code (2007) specifications. The optimum designs are carried out by selecting suitable sections from a specified list including W profiles taken from American Institute of Steel Construction (AISC). The stress constraints obeying AISC-Load and Resistance Factor Design (LRFD) specifications, lateral displacement constraints and geometric constraints are considered in the optimum designs. A computer program is coded in MATLAB for the purpose to incorporate with SAP2000 OAPI (Open Application Programming Interface) to perform structural analysis of the frames under earthquake loads. Three different steel space frames are carried out for four different seismic earthquake zones defined in Turkish Earthquake Code (2007). Results obtained from the examples show the applicability and robustness of the method.