• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.5 no.1
• /
• pp.21-28
• /
• 2005

This paper proposes a new method for accelerating the search speed of genetic algorithms by taking derivative evaluation and conditional random selection into account in their evolution process. Derivative evaluation makes genetic algorithms focus on the individuals whose fitness is rapidly increased. This accelerates the search speed of genetic algorithms by enhancing exploitation like steepest descent methods but also increases the possibility of a premature convergence that means most individuals after a few generations approach to local optima. On the other hand, derivative evaluation under a premature convergence helps genetic algorithms escape the local optima by enhancing exploration. If GAs fall into a premature convergence, random selection is used in order to help escaping local optimum, but its effects are not large. We experimented our method with one combinatorial problem and five complex function optimization problems. Experimental results showed that our method was superior to the simple genetic algorithm especially when the search space is large.

• Journal of applied mathematics & informatics
• /
• v.13 no.1_2
• /
• pp.247-259
• /
• 2003

Optimal control problem for the exploitaton of oil is investigated. The optimal control problem under consideration in this paper is governed by weak coupled parabolic PDEs and involves with pointwise state and control constraints. The properties of solution of the state equations and the continuous dependence of state functions on control functions are investigated in a suitable function space; existence of optimal solution of the optimal control problem is also proved.

• Journal of the Korea Furniture Society
• /
• v.15 no.1
• /
• pp.27-40
• /
• 2004

Designers in Korea have stuck to development of furniture which has high reliance of foreign national resources. They made mistake that they didn't try to make inroads into the world market. They have kept production system of labor intensive method till 1990. They imitated foreign manufactures to win in domestic economy. It became the complete lack of exploitation experience and brought stagnation of design which couldn't defeat. Now Korea is making progressive impression in territory of an electron and information in a foreign market. A new progress of furniture design which was developed centering around a digital suggest a new appearance that will lead a future with modernization in a space of residence. This sis a new starting point which was most completed by anyone. If we will prepare without delay we can take part in a world market with competitive power.

• Journal of the Semiconductor & Display Technology
• /
• v.6 no.2 s.19
• /
• pp.5-10
• /
• 2007

According to the advantageous features of flash memory, its exploitation and application in mobile and ubiquitous related devices as well as voluminous storage devices is being increased rapidly. The inherent properties that are determined by configuration of flash memory unit might restrict the promising expansion in its utilization. In this paper, we study policies based on threshold values, instead of using global search, in order to satisfy our objective that is to decrease the necessary processing cost or penalty for recycling of flash memory space at the same time minimizing the potential degradation of performance. The proposed cleaning methods create partitions of candidate memory regions, to be reclaimed as free, by utilizing global or dynamic threshold values. The impact of the proposed policies is evaluated through a number of experiments, the composition of the optimal configuration featuring the methods is tested through experiments as well.

• Proceedings of the KIEE Conference
• /
• 1995.07b
• /
• pp.1006-1010
• /
• 1995

This paper describes Sexual Reproduction Genetic Algorithm(SRGA) for function optimization. In SRGA, each individual utilize a diploid chromosome structure. Sex cells(gametes) are produced through artificial meiosis in which crossover and mutation occur. The proposed method has two selection operators, one, individual selection which selects the individual to fertilize, and the other, gamete selection which makes zygote for offspring production. We consider the effects of multi-selection and diploidy on search performance. SRGA improves local and global search(exploitation and exploration) and show optimum tracking performance in nonstationary environments. Gray coding is incorporated to transforming the search space and Genic uniform distribution method is proposed to alleviate the problem of premature convergence.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.06b
• /
• pp.106-108
• /
• 2006

강화 학습은 누적 보상 값을 최대화할 수 있는 행동 선택 전략을 학습하는 온라인 학습의 한 형태이다. 효과적인 강화학습을 위해 학습 에이전트가 매 순간 고민해야 하는 문제가 탐험(exploitation)과 탐색(exploration)의 문제이다. 경험과 학습이 충분치 않은 상태의 에이전트는 어느 정도의 보상 값을 보장하는 과거에 경험한 행동을 선택하느냐 아니면 보상 값을 예측할 수 없는 새로운 행동을 시도해봄으로써 학습의 폭을 넓힐 것이냐를 고민하게 된다. 특히 단일 에이전트에 비해 상태공간과 행동공간이 더욱 커지는 다중 에이전트 시스템의 경우, 효과적인 강화학습을 위해서는 상태 공간 축소방법과 더불어 탐색의 기회가 많은 행동 선택 전략이 마련되어야 한다. 본 논문에서는 로봇축구 Keepaway를 위한 효율적인 다중 에이전트 강화학습 방법을 설명한다. 이 방법의 특징은 상태 공간 축소를 위해 함수근사방법의 하나인 타일 코딩을 적용하였고, 다양한 행동 선택을 위해 룰렛 휠 선택 전략을 적용한 것이다. 본 논문에서는 이 방법의 효과를 입증하기 위한 실험결과를 소개한다.

• Journal of KIISE:Software and Applications
• /
• v.34 no.11
• /
• pp.971-983
• /
• 2007

Cellular Genetic Algorithms(CGAs) are a subclass of Genetic Algorithms(GAs) in which each individuals are placed in a given geographical distribution. In general, CGAs# population space is a regular network that has relatively long characteristic path length and high clustering coefficient in the view of the Networks Theory. Long average path length makes the genetic interaction of remote nodes slow. If we have the population#s path length shorter with keeping the high clustering coefficient value, CGAs# population space will converge faster without loss of diversity. In this paper, we propose Smallest-Small-World Cellular Genetic Algorithms(SSWCGAs). In SSWCGAs, each individual lives in a population space that is highly clustered but having shorter characteristic path length, so that the SSWCGAs promote exploration of the search space with no loss of exploitation tendency that comes from being clustered. Some experiments along with four real variable functions and two GA-hard problems show that the SSWCGAs are more effective than SGAs and CGAs.

• Journal of Korean Society of Archives and Records Management
• /
• v.11 no.1
• /
• pp.253-271
• /
• 2011

The modern age is such an era of time and space compressed. The central axis having compressed the time of the modern Busan city was the very trains and trams. The development of the means of modern transportation, such as trans and trams, came to change the time-space characteristics of cities in the modern age. Through trains and trams regarded as symbols of modern cities, this study attempted to find the localities of Busan as a modern city. The development of the modern Busan city was actually based on modernity and colonial exploitation. Documents of localities provide data to read humans' local-related experiences. 'Documenting localities' related to the means of modern transportation is a work process to read the localities of Busan in the modern age. Through this process, it is possible to understand how means of transportation can be correlated with a local community, local residents' daily lives and spatial change. Overall, this study is such a small attempt for this concern.

• The Korean Journal of Air & Space Law and Policy
• /
• v.9
• /
• pp.445-488
• /
• 1997

In the forthcoming 21st century new technical and scientific developments in outer space demands new approaches towards the problems arising in several fields of the use and exploitation of outer space including practical applications. The main purposes of this study are to analyze the legal problems of geostationary orbital position, telecommunication, direct television broadcasting by uses of artificial satellites. Communication via artificial Earth satellites was one of the first applications of space technology and is now one of the most developed field. From the technical and economic standpoints the advantages of world-wide satellites communication system are too all obvious. However, as the practical uses of space technology become more freguent, the legal conflicts among nations have become more divisive. One of the problem grown in uses of artificial satellites is that of the increasing shortage of suitable orbital slot positions for satellites, especially in geostationary orbit. Legal status of geostationary orbit as a limited resourece have to be reviewed in consideration of the side effect of the "First use, first-served" principle. The geostationary orbit is to be used for the benifits of all mankind and to be guaranteed for each state institutionaly in order to have eguitable access to the use of the orbit. Rapid increase of satellites broadcasting system in not only developed countries but also in developing countries opened up new possibilities with one another's scientific and cultural achievements. But there is also a potential danger that this powerful new instrument of influencing public opinion will be abused. Such a danger incudes spill-over or harmful interference. This controversial issue brings about the question whether prior consent from the receiver nation is needed to broadcast across international boundaries. Some states have rejected prior consent because it interfere with the free flow of information. Many other countries have opposed that opinion as an invasion and violation of sovereignty and as a violation of the 1967 Treaty and the UN Charter. Since declaration of the First Year of Outer Space in 1985, our country have promoted the plan of launching communication and broadcasting satellites. With the Koreasat launched in 1995 as the start, a real satellite-telecommunication era was opened in korea. According to this new development of our country, there will also rise various legal problems related to satellite broadcasting and telecommunication such as the inflow of foreign programs, the permeation of culture and the infringement of program copyright. Consequently the effective reactions to these problems in satellite-communication era should be tried including international cooperation. It is therefore to take into careful consideration the legal issues which may arise in outer space activities and to formulate positive policy on international cooperation with surrounding or advanced countries and international organization concerned. For this purpose the United Nations also prepares the UNISPACE III in 1999, to enable the international community to meet a more promising 21st century.

• Journal of KIISE:Databases
• /
• v.31 no.5
• /
• pp.457-467
• /
• 2004

The efficiency of algorithms managing data caches has a major impact on the performance of systems that utilize client-side data caching. In these systems, two versions of data can be maintained without an additional space overhead of the server by exploiting the replication of data in the server's buffer and clients' caches. In this paper, we present a new cache consistency algorithm employing versions: Two Versions-Callback Locking (2V-CBL). Our experimental results indicate that 2V-CBL provides good performance, particularly outperforms a leading cache consistency algorithm, Asynchronous Avoidance-based Gache Consistency, when some clients run only read-only transactions.