• 제목/요약/키워드: Key Evolution

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A Hybrid Evolution Strategy on the Rectilinear Steiner Tree

  • Yang, Byoung-Hak
    • 한국경영과학회:학술대회논문집
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    • 한국경영과학회 2005년도 추계학술대회 및 정기총회
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    • pp.27-37
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    • 2005
  • The rectilinear Steiner tree problem (RSTP) is to find a minimum-length rectilinear interconnection of a set of terminals in the plane. It is well known that the solution to this problem will be the minimal spanning tree (MST) on some set Steiner points. The RSTP is known to be NP-complete. The RSTP has received a lot of attention in the literature and heuristic and optimal algorithms have been proposed, A key performance measure of the algorithm for the RSTP is the reduction rate that is achieved by the difference between the objective value of the RSTP and that of the MST without Steiner points. A hybrid evolution strategy on RSTP based upon the Prim algorithm was presented. The computational results show that the evolution strategy is better than the previously proposed other heuristic. The average reduction rate of solutions from the evolution strategy is about 11%, which is almost similar to that of optimal solutions.

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Differential Evolution Algorithm for Job Shop Scheduling Problem

  • Wisittipanich, Warisa;Kachitvichyanukul, Voratas
    • Industrial Engineering and Management Systems
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    • 제10권3호
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    • pp.203-208
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    • 2011
  • Job shop scheduling is well-known as one of the hardest combinatorial optimization problems and has been demonstrated to be NP-hard problem. In the past decades, several researchers have devoted their effort to develop evolutionary algorithms such as Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) for job shop scheduling problem. Differential Evolution (DE) algorithm is a more recent evolutionary algorithm which has been widely applied and shown its strength in many application areas. However, the applications of DE on scheduling problems are still limited. This paper proposes a one-stage differential evolution algorithm (1ST-DE) for job shop scheduling problem. The proposed algorithm employs random key representation and permutation of m-job repetition to generate active schedules. The performance of proposed method is evaluated on a set of benchmark problems and compared with results from an existing PSO algorithm. The numerical results demonstrated that the proposed algorithm is able to provide good solutions especially for the large size problems with relatively fast computing time.

진화 교육 연구 경험 유무에 따른 생명과학 교사의 교수 실행 사례 연구 (Case Study of Teaching Practices of Biology Teachers with and without Research Experience in Evolution Education)

  • 고유선;차희영;임미리
    • 한국과학교육학회지
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    • 제37권4호
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    • pp.747-761
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    • 2017
  • 이 연구는 생명 과학 교수 실행에 있어서 진화 교육 연구 경험이 있는 교사가 그렇지 않은 교사와 어떤 차이를 나타내는지 알아보기 위해 수행되었다. 연구를 위해 진화 교육에 대한 연구 경험이 있는 교사 두 명과 이에 대한 비교집단으로 진화 교육에 대한 연구 경험이 없는 교사 두 명, 총 네 명의 생명과학 교사들을 목적 표집하였다. 먼저, 사전면담을 통해 교사들의 배경지식을 수집하였으며, 생명과학 수업 중 진화 단원과 비진화 단원을 각각 2차시씩 선정하였다. 녹음된 수업은 전사하였으며, 교사들의 진화에 대한 견해 및 교수 실행에 반영된 진화 내용을 중심으로 분석하였다. 또한, 연구를 위한 기초자료로 과학 교수내용지식 설문지, 진화론의 개념 검사지, 진화론의 수용 검사지를 사용하여 자료수집 및 분석 하였다. 연구결과 교사들의 진화 개념에 대한 이해 수준은 진화의 중요성 인식과는 관련이 없는 것으로 나타났다. 다만, 교사 개인의 종교적인 신념이나, 진화의 중요성을 인식하는 것에 대한 필요 자체를 느끼지 못함이 진화의 중요성 인식에 부정적인 영향을 미쳤다. 이 때문에 진화교육 연구 미경험 교사들은 진화의 중요성을 인식할 수 있는 교사 재교육 기회도 거부하는 경향을 보였다. 또한 미경험 교사들은 교과서 및 교육과정에서 나타난 진화 개선점에 대해 피상적으로만 파악하고 있었다. 생명과학 교수 실행 내용을 분석한 결과 경험 교사들의 진화 주요 개념 활용 비율이 더 높게 나타났다. 그리고 경험 교사들만이 자신의 교수 실행에서 나타난 오개념을 스스로 인지하고 이러한 오개념이 나타나게 된 원인에 대해 설명을 했다. 이를 통해 진화 교육 연구 경험 교사가 진화 주요 개념들을 폭넓게 활용할 뿐만 아니라 진화 관련 오개념 방지에 더 실천적임을 확인하였다. 연구 결과는 생물 교육에서 진화의 중요성을 깨닫지 못한 교사들에게 좀 더 다양하고 많은 진화 관련 교사교육 프로그램을 제공할 필요성을 알려준다.

Dynamic evolution characteristics of water inrush during tunneling through fault fracture zone

  • Jian-hua Wang;Xing Wan;Cong Mou;Jian-wen Ding
    • Geomechanics and Engineering
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    • 제37권2호
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    • pp.179-187
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    • 2024
  • In this paper, a unified time-dependent constitutive model of Darcy flow and non-Darcy flow is proposed. The influencing factors of flow velocity are discussed, which demonstrates that permeability coefficient is the most significant factor. Based on this, the dynamic evolution characteristics of water inrush during tunneling through fault fracture zone is analyzed under the constant permeability coefficient condition (CPCC). It indicates that the curves of flow velocity and hydrostatic pressure can be divided into typical three stages: approximate high-velocity zone inside the fault fracture zone, velocity-rising zone near the tunnel excavation face and attenuation-low velocity zone in the tunnel. Furthermore, given the variation of permeability coefficient of the fault fracture zone with depth and time, the dynamic evolution of water flow in the fault fracture zone under the variable permeability coefficient condition (VPCC) is also studied. The results show that the time-related factor (α) affects the dynamic evolution distribution of flow velocity with time, the depth-related factor (A) is the key factor to the dynamic evolution of hydrostatic pressure.

The Key role of the Bulge Compactness in Star-forming Activity in Late-type Galaxies

  • Jee, Woong-bae;Yoon, Suk-Jin
    • 천문학회보
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    • 제40권2호
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    • pp.32.2-32.2
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    • 2015
  • Which mechanism governs star-formation activity in galaxies is still one of the most important, open questions in galactic astronomy. To address this issue, we investigate the specific star formation rate (sSFR) of late-type galaxies as functions of various structural parameters including the morphology, mass, radius, and mass compactness (MC). We use a sample of ~200,000 late-type galaxies with z = 0.02 ~ 0.2 from SDSS DR7 and a catalog of bulge-disk decomposition (Simard et al. 2011; Mendel et al. 2013). We find a remarkably strong correlation between bulge's MC and galaxy's sSFR, in the sense that galaxies with more compact bulge tend to be of lower sSFR. This seems counter-intuitive given that galactic sSFR is driven predominantly by disks rather than bulges and suggests that the central mass density plays a key role in recent star-forming activity. We discuss the physical cause of the new findings in terms of the bulge growth history and AGN activities.

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Analytic Throughput Model for Network Coded TCP in Wireless Mesh Networks

  • Zhang, Sanfeng;Lan, Xiang;Li, Shuang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제8권9호
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    • pp.3110-3125
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    • 2014
  • Network coding improves TCP's performance in lossy wireless networks. However, the complex congestion window evolution of network coded TCP (TCP-NC) makes the analysis of end-to-end throughput challenging. This paper analyzes the evolutionary process of TCP-NC against lossy links. An analytic model is established by applying a two-dimensional Markov chain. With maximum window size, end-to-end erasure rate and redundancy parameter as input parameters, the analytic model can reflect window evolution and calculate end-to-end throughput of TCP-NC precisely. The key point of our model is that by the novel definition of the states of Markov chain, both the number of related states and the computation complexity are substantially reduced. Our work helps to understand the factors that affect TCP-NC's performance and lay the foundation of its optimization. Extensive simulations on NS2 show that the analytic model features fairly high accuracy.

Seven New Records of the Family Proctotrupidae (Hymenoptera: Proctotrupoidea) from South Korea

  • Park, Bia;Lee, Jong-Wook
    • Animal Systematics, Evolution and Diversity
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    • 제37권1호
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    • pp.39-51
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    • 2021
  • The South Korean species of family Proctotrupidae Latreille, 1802 (Hymenoptera: Proctotrupoidea) are studied. Here, seven proctotrupid species are newly added in the South Korean fauna: Cryptoserphus aculeator (Haliday), Disogmus basalis (Thomson), Mischoserphus arcuator (Stelfox), M. samurai (Pschorn-Walcher), Nothoserphus scymni (Ashmead), Proctotrupes gravidator (Linnaeus), and Tretoserphus laricis (Haliday). Which of them, four genera belonging to the tribes Cryptoserphini and Proctotrupini (Cryptoserphus, Mischoserphus, Proctotrupes, and Tretoserphus) are also newly recorded from South Korea. A key to genera of South Korean Proctotrupidae, diagnosis, photographs, distribution, and recorded hosts for each species are presented. All proctotrupid specimens were kept in the collections of the Geolim Entomological Institute, Daegu, South Korea.

Species Diversity of Hypogeous Ascomycetes in Israel

  • Barseghyan, Gayane S.;Wasser, Solomon P.
    • Mycobiology
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    • 제38권3호
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    • pp.159-165
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    • 2010
  • We conducted a species diversity study of the hypogeous Ascomycetes of Israel. The hypogeous Ascomycetes in Israel include members of the families Pyronemataceae, Pezizaceae, and Tuberaceae, which are represented by seven species: Hydnocystis piligera, Terfezia arenaria, T. claveryi, T. oligosperma, Tirmania africana, Tuber asa, and T. nitidum; only T. asa is new to Israeli mycobiota. Synonymy, locations, collection data, general distribution, distribution in Israel, descriptions, a key to identification, illustrations, and taxonomic remarks are provided.

Active black holes in "normal" galaxies

  • Woo, Jong-Hak
    • 천문학회보
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    • 제42권2호
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    • pp.37.2-37.2
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    • 2017
  • Since the discovery of quasars about a half century ago, it has been an open question what triggers supermassive black holes at the center of galaxies. I will talk about AGNs and their host galaxies in the context of galaxy assembly and evolution. In particular, I will focus on the fundamental, but unanswered question whether black holes play a key role in galaxy evolution from my personal perspective.

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Study on bearing characteristic of rock mass with different structures: Physical modeling

  • Zhao, Zhenlong;Jing, Hongwen;Shi, Xinshuai;Yang, Lijun;Yin, Qian;Gao, Yuan
    • Geomechanics and Engineering
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    • 제25권3호
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    • pp.179-194
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    • 2021
  • In this paper, to study the stability of surrounding rock during roadway excavation in different rock mass structures, the physical model test for roadway excavation process in three types of intact rock mass, layered rock mass and massive rock mass were carried out by using the self-developed two-dimensional simulation testing system of complex underground engineering. Firstly, based on the engineering background of a deep mine in eastern China, the similar materials of the most appropriate ratio in line with the similarity theory were tested, compared and determined. Then, the physical models of four different schemes with 1000 mm (height) × 1000 mm (length) × 250 mm (width) were constructed. Finally, the roadway excavation was carried out after applying boundary conditions to the physical model by the simulation testing system. The results indicate that the supporting effect of rockbolts has a great influence on the shallow surrounding rock, and the rock mass structure can affect the overall stability of the surrounding rock. Furthermore, the failure mechanism and bearing capacity of surrounding rock were further discussed from the comparison of stress evolution characteristics, distribution of stress arch, and failure modes in different schemes.