• 한국자동차공학회논문집
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• 제5권1호
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• pp.207-216
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• 1997

We developed the durability estimation and design systems to minimize the volume, considering the durability, efficiency, and design requirements of worm gears. That is, we consider each kind of factors affecting on durability on the basis of AGMA Standard for the cylindrical and double-enveloping worm gears. We also estimate input power on the basis of wear and durability, bending strength and deflection of worm shaft, and we developed the durability estimation and design systems of power transmission worm gears introducing the optimal design method on the personal computer to be easily used in field. Also, we developed a method which converts the design variables obtained from the optimal design method to integer values(number of worm threads, number of worm threads, number of worm wheel teeth, etc.,) to be used in real design and production. The developed durability estimation and design method can be easily applied to the design of worm gears used as power transmission devices in machineries and is expected to be used for weight minimization of worm gear unit.

• 대한전기학회논문지:전력기술부문A
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• 제53권5호
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• pp.266-274
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• 2004

This paper presents a scheme for the interconnection of dispersed generator systems(DGs) based on load .unbalance and load model in composite distribution systems. Groups of each individual load model consist of residential, industrial, commercial, official and agricultural load. The unbalance is involved with many single-phase line segment. . Voltage profile improvement and system loss minimization by installation of DGs depend greatly on how they are placed and operated in the distribution systems. So, DGs can reduce distribution real power losses and replace large-scale generators if they are placed appropriately in the distribution systems. The main idea of solving fuzzy goal programming is to transform the original objective function and constraints into the equivalent multi-objectives functions with fuzzy sets to evaluate their imprecise nature for the criterion of power loss minimization, the number or total capacity of DGs and the bus voltage deviation, and then solve the problem using genetic algorithm. The method proposed is applied to IEEE 13 bus and 34 bus test systems to demonstrate its effectiveness.

• Journal of Communications and Networks
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• 제12권4호
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• pp.334-345
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• 2010

In this paper, we study optimal tradeoffs of achievable throughput versus consumed power in wireless ad-hoc networks formed by a collection of multiple antenna nodes. Relying on adaptive modulation and/or dynamic channel coding rate allocation techniques for multiple antenna systems, we examine the maximization of throughput under power constraints as well as the minimization of transmission power under throughput constraints. In our examination, we also consider the impacts of enforcing quality of service requirements expressed in the form of channel coding block loss constraints. In order to properly model temporally correlated loss observed in fading wireless channels, we propose the use of finite-state Markov chains. Details of fading statistics of signal-to-interference-noise ratio, an important indicator of transmission quality, are presented. Further, we objectively inspect complexity versus accuracy tradeoff of solving our proposed optimization problems at a global as oppose to a local topology level. Our numerical simulations profile and compare the performance of a variety of scenarios for a number of sample network topologies.

• 한국통신학회논문지
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• 제36권12B호
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• pp.1548-1555
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• 2011

UDSM(Ultra Deep SubMicron)기술을 이용한 시스템 온-칩 설계 시 가창 중요한 설계 요소는 버스 상에서의 전력소모와 지연시간을 최소화 하는 것이다. 인접한 선에서 발생되는 crosstalk는 전파 지연을 발생시키는데 지대한 영향을 미치며, 이를 제거하거나 최소화 시키는 일은 SoC(System on a Chip) 설계에서 시스템의 신뢰성 및 성능 향상과 직결된다. 기존의 방법들은 주로 crosstalk 지연이나 버스 스위칭 횟수 중 하나 만을 최소화하는 방법이 제안되었다. 본 논문에서는 인코딩 적용 4 비트 클러스터 상의 버스 스위칭 횟수에 따라 crosstalk과 스위칭 횟수를 동시에 최소화 할 수 있도록 "invert" 기능과 "logic-convert" 기능을 적응적으로 선택하는 새로운 인코딩 기법을 제안한다. 실험결과 제안한 버스 인코딩 기법은 완벽하게 crosstalk 지연를 제거한 반면, 기존의 다른 방법들에 비해 25% 이상 전력을 절약하였음을 보여준다.

• 대한기계학회논문집
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• 제19권8호
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• pp.1799-1809
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• 1995

The applicability of the field-consistency paradigm, which was originally employed for analysis of locking due to constrained energy having the second power of a strain, is extended to the constrained energy having a quadratic form of strain. For the extension, nearly-incompressible plane strain problem is considered by introducing the concept of reduced minimization. The field-consistent analysis of the plane strain problem leads to a clear and systematic understanding on the relation amongst constraints imposed on element, spurious constraint -free optimal points, and integration order used.

• 전기학회논문지
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• 제60권4호
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• pp.705-710
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• 2011

This paper proposes establishment of generator maintenance scheduling(GMS) considering minimization of $CO_2$ emissions. The objective function model to minimize $CO_2$ emissions is used in this paper. In this paper, and also, GMS is established due to freedom of GMS of generators owned by a designated generation company. The practicality and effectiveness of the proposed approach are demonstrated by simulation studies for a real size power system model in Korea in 2010.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1187-1188
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• 2006

This paper a new method which applies a genetic algorithm for determining which sectionalizing switch to operate in order to solve the distribution system loss minimization re-configuration problem. In addition, the proposed method introduces a ultra efficient MPP tracking in a solar power generation system.

• Journal of Power Electronics
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• 제9권6호
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• pp.940-948
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• 2009

The main objective of this a paper is to improve the efficiency of permanent magnet synchronous motors (PMSMs) by using an improved direct torque control (DTC) strategy. The basic idea behind the proposed strategy is to predict the impact of a small change in the stator flux amplitude at each sampling period to decrease electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to fulfill the flux change. The motor drive simulations confirm a significant improvement in efficiency as well as a very fast and smooth response under the proposed strategy.

• 동력기계공학회지
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• 제2권3호
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• pp.60-67
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• 1998

Edge detection is the first step and very important step in image analysis. We cast edge detection as a problem in cost minimization. This is achieved by the formulation of a cost function that evaluates the quality of edge configurations. The cost function can be used as a basis for comparing the performances of different detectors. This cost function is made of desirable characteristics of edges such as thickness, continuity, length, region dissimilarity. And we use a simulated annealing algorithm for minimum of cost function. Simulated annealing are a class of adaptive search techniques that have been intensively studied in recent years. We present five strategies for generating candidate states. Experimental results(building image and test image) which verify the usefulness of our simulated annealing approach to edge detection are better than other operator.

• Journal of Electrical Engineering and Technology
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• 제3권1호
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• pp.68-78
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• 2008

This paper introduces a complete package for SRM drive on Power System Computer-Aided Design/Electromagnetic Transients (PSCAD/EMTDC). A three-phase SRM drive is modeled and simulated on PSCAD. The motor is modeled using an accurate nonlinear analytical model that takes into consideration the machine nonlinearities. A current control algorithm is applied for torque ripple minimization to achieve a smooth output torque which is necessary for high performance applications. The motor drive is tested for four-quadrant operations. The modeled SRM is capable of operating as a motor or generator during clockwise and counterclockwise motions. The proposed package helps in understanding the operational principles of switched reluctance motors, investigating the dynamic characteristics of SRM drives, and achieving a high performance dynamic control task.