7,711 research outputs found
Cold Neutron Focusing Multiple Biconcave Lenses and Anti-Gravity Prisms for 40m Small Angle Neutron Scattering Instrument
No full text고성능 슈퍼캐패시터를 위한 그래핀/금속산화물 및 탄소나노어니언/전도성고분자 복합체 개발
No full text학위논문(박사) - 한국과학기술원 : 원자력및양자공학과, 2015.8
,[vii, 83 p. :]슈퍼캐패시터 (전기화학 캐패시터)는 기존의 배터리 대비 매우 빠른 충-방전 시간, 높은 출력 특성, 긴 내부수명 등의 장점으로 말미암아 차세대 전기 에너지 저장 장치로 매우 큰 주목을 받고 있다. 특히 전기 자동차, 하이브리드 자동차, 비상 전력 시스템, 메모리 백업 시스템 등 높은 출력특성과 긴 내부수명이 필요한 다양한 분야에서 슈퍼캐패시터의 응용이 기대되고 있다. 하지만 슈퍼캐패시터는 기존의 상용화된 배터리와 비교했을 때 매우 낮은 에너지 저장 능력을 가지고 있으며 이는 슈퍼캐패시터의 다양한 분야로의 응용을 제한하는 가장 큰 문제가 되고 있다. 따라서 슈퍼캐패시터의 사용 분야를 넓히고 차세대 전기 에너지 저장 장치로 널리 사용되기 위해서는 기존의 높은 출력 특성과 긴 내부수명의 장점을 유지하면서 기존보다 높은 에너지 저장 능력을 제공하는 새로운 형태의 슈퍼캐패시터 개발이 필요하다. 본 연구에서는 각기 다른 전기 에너지 저장 방식을 가지는 재료들의 융합을 통해 기존의 슈퍼캐패시터보다 고 에너지 특성, 고 출력 특성을 가지는 고성능 슈퍼캐패시터 전극 물질을 개발하는데 성공하였다.
먼저, 구겨진 형태를 가지는 질소 도핑 된 박막 그래핀/망가니즈 산화물 복합체를 대량으로 손쉽게 제조할 수 있는 새로운 합성 방법이 성공적으로 개발되었다. 산화 그래핀과 Glycine, 질산망간 (Mn(NO3)2？4H2O)의 혼합물을 500 ℃까지 천천히 가열함으로써 산화 그래핀의 환원, 그래핀의 질소도핑 및 망가니즈 산화물의 생성을 동시에 얻을 수 있었다. 또한 혼합물을 500 ℃까지 가열 후, 액체 질소를 통해 혼합물의 온도를 급격하게 낮춤으로써 심하게 구겨진 형태의 3D 그래핀 구조를 얻을 수 있었다. XRD와 XPS 실험을 통해 분석한 결과 생성된 망가니즈 산화물은 MnO2와 Mn3O4의 형태로 존재함을 확인하였으며, 그래핀의 질소도핑을 통해 pyrrolic 형태의 질소와 pyridine 형태의 질소가 그래핀 내에 존재함을 확인하였다. 제조된 그래핀/망가니즈 산화물 복합체의 전기화학적 특성은 순환전압전류법 (Cyclic-Voltammetry)을 이용하여 측정되었으며, 5mV/sec의 주사속도 조건에서 958 F/g의 매우 높은 캐패시턴스 값을 보여주었다. 특히, 산화 그래핀의 환원, 그래핀의 질소도핑, 망가니즈 산화물의 생성 및 구겨진 그래핀 구조가 각기 시너지 효과를 내면서 보다 높은 캐패시턴스를 얻는데 효과적으로 작용하는 것을 확인할 수 있었다. 이중 금속산화물과 그래핀이 함께 존재할 때 급격한 온도 변화를 통해 얻어진 심하게 구겨진 그래핀 구조는 본 연구에서 처음으로 보고되는 것이며, 이를 통해 일반적인 산화 그래핀 대비 매우 높은 비표면적 (1006 m2/g)과 높은 충-방전 안정성 (1000회의 충-방전 반복실험 이후에도 94.1%의 캐패시턴스 유지)을 얻을 수 있었다...한국과학기술원 :원자력및양자공학과
Fabrication of Highly Conductive and Transparent Carbon Nanotube Thin Films using Layer-by-Layer Self Assembly Method
No full textFabrication of Highly Conductive and Transparent Carbon Nanotube Thin Films using Layer-by-Layer Self Assembly Method
No full textProduction of cloned mice by aggregation of tetraploid embryo
No full textMouse chimeras can also successfully be produced using tetraploid host embryos. This study was conducted to optimize the efficiency of cloning and to produce cloned mice using tetraploid host embryos. Six hours of activation with strontium (SrCl2) was optimal for somatic cell nuclear transfer (SCNT) embryos. Cytochalasin B (CB) concentration (5 μg/ml) during enucleation was evaluated in the efficiency of implantation sites and fetus offspring. Continuous exposure to 5？50 nM trichostatin A (TSA), a histone-deacetylase inhibitor (HDACi), for 10 h is recommended for production of clone mice. Aggregated SCNTs were constructed by aggregation of SCNT embryos with tetraploid embryos to reduce epigenetic errors in the placenta. The pregnancy and implantation rates of aggregated SCNT were significantly higher than those of SCNT alone. The full-term developmental rate of aggregated embryos was also higher than that of SCNT (3.57 vs. 1.16). The placental weight of SCNT clones was significantly higher than that from in vitro fertilization (IVF). However, the placenta weight of aggregated SCNT clones was nearly the same as that of embryos in the IVF group. The placentas of SCNT-only clones appeared to have the hyperplastic histology typical of mouse clones. We produced a total of 36 clone mice, including nine heads derived from aggregated SCNT. One-half of clones derived from aggregated SCNT survived to adulthood, and 14-clones derived from SCNT grew into healthy adults. The aggregated SCNT method was useful for significantly reducing the placental weight of cloned mice and improving the efficiency of SCNT.open
DEMAEX SIM Simulator inovasi terbaharu Dr. Lee Chia Kuang
No full textGAMBANG, 15 Jun 2021 - DEMAEX-SIM atau dikenali sebagai DEMATEL EXCEL Simulator adalah inovasi terbaharu daripada penyelidik dan pensyarah kanan, Fakulti Pengurusan Industri, Universiti Malaysia Pahang (UMP), Dr. Lee Chia Kuang, 36 tahun
Agent-Based Cloud Computing
No full textAgent-based cloud computing is concerned with the design and development of software agents for bolstering cloud service
discovery, service negotiation, and service composition. The significance of this work is introducing an agent-based paradigm for
constructing software tools and testbeds for cloud resource management. The novel contributions of this work include: 1) developing
Cloudle: an agent-based search engine for cloud service discovery, 2) showing that agent-based negotiation mechanisms can be
effectively adopted for bolstering cloud service negotiation and cloud commerce, and 3) showing that agent-based cooperative problemsolving
techniques can be effectively adopted for automating cloud service composition. Cloudle consists of 1) a service discovery agent
that consults a cloud ontology for determining the similarities between providers’ service specifications and consumers’ service
requirements, and 2) multiple cloud crawlers for building its database of services. Cloudle supports three types of reasoning: similarity
reasoning, compatibility reasoning, and numerical reasoning. To support cloud commerce, this work devised a complex cloud
negotiation mechanism that supports parallel negotiation activities in interrelated markets: a cloud service market between consumer
agents and broker agents, and multiple cloud resource markets between broker agents and provider agents. Empirical results show that
using the complex cloud negotiation mechanism, agents achieved high utilities and high success rates in negotiating for cloud resources.
To automate cloud service composition, agents in this work adopt a focused selection contract net protocol (FSCNP) for dynamically
selecting cloud services and use service capability tables (SCTs) to record the list of cloud agents and their services. Empirical results
show that using FSCNP and SCTs, agents can successfully compose cloud services by autonomously selecting services
Bo Sung Sim (1924–2001): a pioneer of neurosurgery in Korea
No full textBo Sung Sim (1924–2001) stands as a prominent figure in the history of Korean neurosurgery. His devoted contributions
have led to the fruitful development of modern neurosurgery in Korea. Sim practiced advanced neurosurgical
techniques, undertook basic research, was passionate about education in the early years of neurosurgery in Korea, and
played an essential role in founding the Korean Neurosurgical Society. Sim was a true neurosurgeon—a teacher, a scientist,
and a superb pioneer in Korean neurosurgery
Evolving Fuzzy Rules for Relaxed-Criteria Negotiation
No full textIn the literature on automated negotiation, very few negotiation agents are designed with the flexibility to slightly relax their negotiation criteria to reach a consensus more rapidly and with more certainty. Furthermore, these relaxed-criteria negotiation agents were not equipped with the ability to enhance their performance by learning and evolving their relaxed-criteria negotiation rules. The impetus of this work is designing market-driven negotiation agents (MDAs) that not only have the flexibility of relaxing bargaining criteria using fuzzy rules, but can also evolve their structures by learning new relaxed-criteria fuzzy rules to improve their negotiation outcomes as they participate in negotiations in more e-markets. To this end, an evolutionary algorithm for adapting and evolving relaxed-criteria fuzzy rules was developed. Implementing the idea in a testbed, two kinds of experiments for evaluating and comparing EvEMDAs (MDAs with relaxed-criteria rules that are evolved using the evolutionary algorithm) and EMDAs (MDAs with relaxed-criteria rules that are manually constructed) were carried out through stochastic simulations. Empirical results show that: 1) EvEMDAs generally outperformed EMDAs in different types of e-markets and 2) the negotiation outcomes of EvEMDAs generally improved as they negotiated in more e-markets
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