• Title/Summary/Keyword: Defense behavior

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Thermal Conductivity and Thermal Expansion Behavior of Pseudo-Unidirectional and 2-Directional Quasi-Carbon Fiber/Phenolic Composites

  • Cho, Donghwan;Choi, Yusong;Park, Jong Kyoo;Lee, Jinyong;Yoon, Byung Il;Lim, Yun Soo
    • Fibers and Polymers
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    • v.5 no.1
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    • pp.31-38
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    • 2004
  • In the present paper, a variety of fiber reinforcements, for instance, stabilized OXI-PAN fibers, quasi-carbon fibers, commercial carbon fibers, and their woven fabric forms, have been utilized to fabricate pseudo-unidirectional (pseudo-UD) and 2-directional (2D) phenolic matrix composites using a compression molding method. Prior to fabricating quasi-carbon fiber/phenolic (QC/P) composites, stabilized OXI-PAN fibers and fabrics were heat-treated under low temperature carbonization processes to prepare quasi-carbon fibers and fabrics. The thermal conductivity and thermal expansion/contraction behavior of QC/P composites have been investigated and compared with those of carbon fiber/phenolic (C/P) and stabilized fiber/phenolic composites. Also, the chemical compositions of the fibers used have been characterized. The results suggest that use of proper quasi-carbonization process may control effectively not only the chemical compositions of resulting quasi-carbon fibers but also the thermal conductivity and thermal expansion behavior of quasi-carbon fibers/phenolic composites in the intermediate range between stabilized PAN fiber- and carbon fiber-reinforced phenolic composites.

The Emotional Intelligence, Defense Mechanism and Interpersonal Caring Behavior by Enneagram Personality Types in Nursing Students (에니어그램 성격유형에 따른 간호대학생의 정서지능, 방어기제와 대인돌봄행위)

  • Shin, Eun-Sun;Lee, Sook
    • The Journal of Korean Academic Society of Nursing Education
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    • v.22 no.4
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    • pp.514-526
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    • 2016
  • Purpose: This study was to identify the emotional intelligence, defense mechanism and interpersonal caring behavior by enneagram personality types in nursing students. Methods: A descriptive survey design was used and data were collected using questionnaires from a sample of 263 nursing students. The data were analyzed using by t-test, ANOVA, Pearson's correlation coefficient analysis with SPSS 20.0. Results: In the enneagram personality types, the nursing students was highly measured the type 9(Peacemaker). Emotional intelligence was significantly associated with financial status of parents, motivation of admission and satisfaction of nursing by enneagram characters. Hoping and sharing of interpersonal caring behaviors were significantly differentiated with the power type of enneagram personality. And active listening, comforting, participating of interpersonal caring behaviors were the most popular among the 9 types of personality. There was a positive correlation between emotional intelligence and interpersonal caring behavior. Conclusion: This study suggest that nursing students should be educated the interpersonal caring behavior program considering emotional intelligence and enneagram personality types.

Study on the sintering Behavior of Mechanecally Alloyed 75W-25Cu Powder Using a Dilatometry Technique

  • Lee, Seong-;Hong, Moon-Hee;Kim, Eun-Pyo-;Houng-Sub;Noh, Joon-Woong
    • Proceedings of the Materials Research Society of Korea Conference
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    • 1992.05b
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    • pp.126-126
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    • 1992
  • Solid and liquid sintering behaviors of mechanically alloyed 75W-25Cu powders have been studied by using a dilatometry technique. The sintering was performed under hydrogen atmosphere of 1 atm with a heating rate of 3 $^{\circ}C$/min. The mechanically alloyed 75W-25Cu powders were prepared by high energy ball milling process under argon atmosphere of 1 atm with alloying times of 0 to 400 h. To compare with the sintering behaviors of mechanically alloyed powders, pure Cu and W powders were also sintered under the above conditions, As the mechanical alloying time increased from 0 to 400 h, the shrinkage behavior of the alloyed powders was enhanced during the sintering, and staring temperature of liquid sintering decreased from 1083 to 1068 $^{\circ}C$. The saturation temperature, above which the shrinkage was completed, of liquid phase sintering decreased from 1248 to 1148 $^{\circ}C$ with increasing mechanical alloying time from 200 to 400 h. The residual stress of the mechanically alloyed powder was measured by X-raydiffractometer. The microstructure of sintered spcimen was observed by optical and scanning electron microscope. From these results, variations of solid and liquid sintering behaviors with mechanical alloying time were discussed in terms of the amount of residual stress and the distribution of W and Cu powders in the mechanically alloyed powder.

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Sintering Behavior and Microstructures of Tantalum and Tantalum-Tungsten Alloys Powders (탄탈륨 및 탄탈륨-텅스텐 합금 분말의 소결성 및 미세조직 연구)

  • Kim, Youngmoo;Yang, Sung Ho;Lee, Seong;Lee, Sung Ho;Noh, Joon-Woong
    • Journal of Powder Materials
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    • v.27 no.5
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    • pp.373-380
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    • 2020
  • The purpose of this study is to investigate the densification behavior and the corresponding microstructural evolution of tantalum and tantalum-tungsten alloy powders for explosively formed liners. The inherent inhomogeneous microstructures of tantalum manufactured by an ingot metallurgy might degrade the capability of the warhead. Therefore, to overcome such drawbacks, powder metallurgy was incorporated into the near-net shape process in this study. Spark plasma-sintered tantalum and its alloys with finer particle sizes exhibited higher densities and lower grain sizes. However, they were contaminated from the graphite mold during sintering. Higher compaction pressures in die and isostatic compaction techniques also enhanced the sinterability of the tantalum powders; however, a full densification could not be achieved. On the other hand, the powders exhibited full densification after being subjected to hot isostatic pressing over two times. Consequently, it was found that the hot isostatic-pressed tantalum might exhibit a lower grain size and a higher density as compared to those obtained in previous studies.

PRI: A Practical Reputation-based Incentive Scheme for Delay Tolerant Networks

  • Zhang, Xi;Wang, Xiaofei;Liu, Anna;Zhang, Quan;Tang, Chaojing
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.6 no.4
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    • pp.973-988
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    • 2012
  • Delay tolerant networks (DTNs) characterized by the lack of guaranteed end-to-end paths exploit opportunistic data forwarding mechanism, which depends on the hypothesis that nodes are willing to store, carry, and forward the in-transit messages in an opportunistic way. However, this hypothesis might easily be violated by the presence of selfish nodes constrained with energy, bandwidth, and processing power. To address this problem, we propose a practical reputation-based incentive scheme, named PRI, to stimulate honest forwarding and discipline selfish behavior. A novel concept of successful forwarding credential and an observation protocol are presented to cope with the detection of nodes' behavior, and a reputation model is proposed to determine egoistic individuals. The simulation results demonstrate the effectiveness and practicality of our proposal.

Indicator-based Behavior Ontology for Detecting Insider Threats in Network Systems

  • Kauh, Janghyuk;Lim, Wongi;Kwon, Koohyung;Lee, Jong-Eon;Kim, Jung-Jae;Ryu, Minwoo;Cha, Si-Ho
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.10
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    • pp.5062-5079
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    • 2017
  • Malicious insider threats have increased recently, and methods of the threats are diversifying every day. These insider threats are becoming a significant problem in corporations and governments today. From a technology standpoint, detecting potential insider threats is difficult in early stage because it is unpredictable. In order to prevent insider threats in early stage, it is necessary to collect all of insiders' data which flow in network systems, and then analyze whether the data are potential threat or not. However, analyzing all of data makes us spend too much time and cost. In addition, we need a large repository in order to collect and manage these data. To resolve this problem, we develop an indicator-based behavior ontology (IB2O) that allows us to understand and interpret insiders' data packets, and then to detect potential threats in early stage in network systems including social networks and company networks. To show feasibility of the behavior ontology, we developed a prototype platform called Insider Threat Detecting Extractor (ITDE) for detecting potential insider threats in early stage based on the behavior ontology. Finally, we showed how the behavior ontology would help detect potential inside threats in network system. We expect that the behavior ontology will be able to contribute to detecting malicious insider threats in early stage.

Micro-Cracked Textile Composite Structures‘ Behavior on the Dynamic Impact Loading (동적 충격하중에 의한 미소균열 직조복합구조의 특성)

  • Hur, Hae-Kyu;Kim, Min-Sung;Jung, Jae-Kwon;Kim, Yong-Jin
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.222-227
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    • 2008
  • This study is focused on an integrated numerical modeling enabling one to investigate the dynamic behavior and failure of 2-D textile composite and 3-D orthogonal woven composite structures weakened by micro-cracks and subjected to an impact load. The integrated numerical modeling is based on: I) determination of governing equations via a three-level hierarchy: micro-mechanical unit cell analysis, layer-wise analysis accounting for transverse strains and stresses, and structural analysis based on anisotropic plate layers, II) development of an efficient computational approach enabling one to perform transient response analyses of 2-D plain woven and 3-D orthogonal woven composite structures featuring the matrix cracking and exposed to time-dependent loads, III) determination of the structural characteristics of the textile-layered composites and their degraded features under various geometrical yarn shapes, and finally, IV) assessment of the implications of stiffness degradation on dynamic response to impact loads.

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National Defense Decision-Making : Prospects and New Directions (국방의사결정 : 전망과 대비방향)

  • Gwon Tae-Yeong
    • Journal of the military operations research society of Korea
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    • v.16 no.1
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    • pp.18-34
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    • 1990
  • In light of the recent developments of transitory nature, it is likely that national defense decision-making will be more difficult to make for years to come. In other words, sudden changes in security environment would call into question the basic assumptions on which we have built our national defense planning and increase the number of the uncertain factors in the decision-making process; the subdivision and ramification of national defense management would increase the factors for decision-making and complicate even further the mutual interactions among these factors; the accelerated pace of sophistication and diversification of weapon systems and military technology would increase the risk of failure and system costs geometrically; and the reduced level of acceptance among the people on the sanctification of national defense in proportion to the rapid progress toward a more democratic and industrial society would engender an increased criticism or checking role by the National Assembly or by the mass media. As the changes in national defense environment and conditions create an innumerable number of new tasks, this paper intends to suggest a few core policy measures to improve the quality of national defense decision-making. More specifically, it proposes to 1) eradicate entirely the bureaucratic behavior and tendencies; 2) utilize actively the brain staff for quality assurance of decision-making; 3) and introduce and apply as a whole set, a total system, or an incorporated pack age the PPBEES(Planning-Programming-Budgeting-Executing-Evaluating-System)/LCMM (Life-Cycle Management Model for System Acquision), the OR/SA(Operations Research/Systems Analysis), and DMIS (Defense Management Information System).

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Theoretical Study on the Consolidation Behavior and Mechanical Property for Molybdenum Powders (몰리브데늄 분말의 치밀화 거동 및 기계적 물성의 이론적 연구)

  • Kim, Young-Moo
    • Journal of Powder Materials
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    • v.15 no.3
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    • pp.214-220
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    • 2008
  • In this study, consolidation behavior and hardness of commercially available molybdenum powder were investigated. In order to analyze compaction response of the powders, the elastoplastic constitutive equation based on the yield function by Shima and Oyane was applied to predict the compact density under uniaxial pressure from 100MPa to 700MPa. The compacts were sintered at $1400-1600^{\circ}C$ for 20-60 min. The sintered density and grain size of molybdenum were increased with increasing the compacting pressure and processing temperature and time. The constitutive equation, proposed by Kwon and Kim, was applied to simulate the creep densification rate and grain growth of molybdenum powder compacts. The calculated results were compared with experimental data for the powders. The effects of the porosity and grain size on the hardness of the specimens were explained based on the modified plasticity theory of porous material and Hall-Petch type equation.

A Study on the User Behavior of Korean Defense R&D Researchers (국방연구개발 연구원들의 정보이용 행태에 관한 연구)

  • Song, Jong-Ho;Oh, Dong-Geun
    • Journal of Information Management
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    • v.39 no.2
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    • pp.1-25
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    • 2008
  • This study is to investigate the user behavior of defense development and test researchers working for A research institute to provide advanced library services. Based on the prior studies about the subject, survey through questionnaires were conducted, and the data analyzed using SPSS 12.0. Results of the analyses are as follows: The researchers generally gathered information 2 to 3 times per month. The major reason for information gathering was to solve problems and do their tasks. They considered accuracy of information as the most important factor when they gather information. Finding and selecting information sources were the most difficult task for them in retrieving, acquiring and using information. They have most frequently used digital materials (67%), printed materials next (26%), and non-book materials (6%). Internet was both the most frequently used and most satisfied information source for the researchers.