• Title, Summary, Keyword: Super stability

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A Study on the Economic Evaluation Model of Splice of Reinforcement Bar(SD500) (초고강도 철근이음의 경제성 평가모델 개발에 관한 연구)

  • Kim, Jae-Yeob;Kim, Dae-Won
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.1
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    • pp.71-76
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    • 2008
  • Recently, the high-rise apartment housings have become a prototype of the urban residential dwelling in Korea and the numbers of one have steadily been increasing. According to this trend, the strength of the construction materials is also fortified to assure the stability and durability of the buildings. Specially, Re-bar of SD500 type is largely used at the construction sites of high-rise building. This study analyzes the current usage of SD500 high-strength re-bar at domestic construction sites. Through the result of this analysis, we develop Economic Evaluation Model that measure economic efficiency of lap splice and coupler splice, which are most commonly used in connection SD500. The evaluation method was applied to construction sites in Seoul in December 2006, and the result revealed that coupler splice is relatively superior in terms of cost efficiency when the re-bar diameter is longer and the concrete strength is lower.

Design Criteria of a Future Container Crane for Megaships (초대형 선박용 차세대 컨테이너 크레인의 설계기준)

  • LEE SUK-JAE;HONG KEUM-Shik
    • Journal of Ocean Engineering and Technology
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    • v.18 no.6
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    • pp.101-107
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    • 2004
  • In this paper, the design criteria of future container crane for megaships are investigated. The current loading/unloading capacity of a typical container crane, roughly 30 moves/hr, is too law to meet the requirements of future super containerships, which are expected over 15,000 TEU. After examining the transition of containerships through the years and studying the research trend in developed countries, the specifications of the container crane that can Meet a 15,000 TEU containership are proposed. The structure, trolley and hoist mechanism, outreach, backreach, capacity, speeds, durability, and stability of the future container crane are described.

High-Performance and Fabrication of Graphene-based Flexible Supercapacitor

  • Ra, Eun Ju;Han, Jae Hee;Kim, Kiwoong;Lee, Sun Suk;Kim, Tae-Ho;An, Ki-Seok;Lim, Jongsun
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.442-442
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    • 2014
  • Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, is one of the most promising energy-storage devices because of its high power density, super-high cycle life, and safe operation. We herein report a synthesis of graphene-based flexible films by kneading method. Thus, a device can be readily made by sandwiching a polymer membrane included ionic liquid electrolytes between two identical graphene-based flexible films. Devices made with these electrodes exhibit ultrahigh energy density values while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-energy, flexible electronics.

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Fabrication of Stable Water/Oil Separation Filter Using Effect of Surface Wettability (표면 젖음성을 이용한 물/오일 분리막 제작)

  • Kim, Dohyeong;An, Taechang
    • Journal of Sensor Science and Technology
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    • v.25 no.3
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    • pp.213-217
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    • 2016
  • The superhydrophobic and superoleophobic meshes surfaces have been used in various applications such as self-cleaning, anti-icing, gas exchange, oil-water separation, sound-wave penetrable anti-wetting structures, etc. In particular, there are many studies for oil-water separation with environmental issues. Because of high pressure and dynamic environment, oil-water separation filters must have stable surface properties as super-hydrophobicity and superoleophobicity. The oleophobicity of surface depends on the surface chemistry and roughness of the surface. The roughness of oleophobic surface enhances its static contact angle and stability. The multi-scale hierarchical structure provides a stable superhydrophobic state by maintaining a Cassie state. In this research, we fabricated a superoleophobic mesh with a multi-scale hierarchical structure to increase the pressure resistance and adjusted a size of the mesh hole.

Alloy Design and Properties of Ni based Superalloy LESS 1: I. Alloy Design and Phase Stability at High Temperature (Ni기 초내열 합금 LESS 1의 합금설계 및 평가: I. 합금 설계 및 고온 상 안정성 평가)

  • Youn, Jeong Il;Kang, Byung Il;Choi, Bong Jae;Kim, Young Jig
    • Journal of Korea Foundry Society
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    • v.33 no.5
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    • pp.215-225
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    • 2013
  • The alloys required for fossil power plants are altered from stainless steel that has been used below $600^{\circ}C$ to Ni-based alloys that can operate at $700^{\circ}C$ for Hyper Super Critical (HSC) steam turbine. The IN740 alloy (Special Metals Co. USA) is proposed for improved rupture strength and corrosion resistance at high temperature. However, previous studies with experiments and simulations on stable phases at about $700^{\circ}C$ indicated the formation of the eta phase with the wasting of a gamma prime phase, which is the most important reinforced phase in precipitation hardened Ni alloys, and this resulted in the formation of precipitation free zones to decrease the strength. On the basis of thermodynamic calculation, the new Ni-based superalloy named LESS 1 (Low Eta Sigma Superalloy) was designed in this study to improve the strengthening effect and structure stability by depressing the formation of topologically close packed phases, especially sigma and eta phases at high temperature. A thermal exposure test was carried out to determine the microstructure stability of LESS 1 in comparison with IN740 at $800^{\circ}C$ for 300 hrs. The experimental results show that a needle-shaped eta phase was formed in the grin boundary and it grew to intragrain, and a precipitation free zone was also observed in IN740, but these defects were entirely controlled in LESS 1.

Design and Implementation of PIC/FLC plus SMC for Positive Output Elementary Super Lift Luo Converter working in Discontinuous Conduction Mode

  • Muthukaruppasamy, S.;Abudhahir, A.;Saravanan, A. Gnana;Gnanavadivel, J.;Duraipandy, P.
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.1886-1900
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    • 2018
  • This paper proposes a confronting feedback control structure and controllers for positive output elementary super lift Luo converters (POESLLCs) working in discontinuous conduction mode (DCM). The POESLLC offers the merits like high voltage transfer gain, good efficiency, and minimized coil current and capacitor voltage ripples. The POESLLC working in DCM holds the value of not having right half pole zero (RHPZ) in their control to output transfer function unlike continuous conduction mode (CCM). Also the DCM bestows superlative dynamic response, eliminates the reverse recovery troubles of diode and retains the stability. The proposed control structure involves two controllers respectively to control the voltage (outer) loop and the current (inner) loop to confront the time-varying ON/OFF characteristics of variable structured systems (VSSs) like POESLLC. This study involves two different combination of feedback controllers viz. the proportional integral controller (PIC) plus sliding mode controller (SMC) and the fuzzy logic controller (FLC) plus SMC. The state space averaging modeling of POESLLC in DCM is reviewed first, then design of PIC, FLC and SMC are detailed. The performance of developed controller combinations is studied at different working states of the POESLLC system by MATLAB-Simulink implementation. Further the experimental corroboration is done through implementation of the developed controllers in PIC 16F877A processor. The prototype uses IRF250 MOSFET, IR2110 driver and UF5408 diodes. The results reassured the proficiency of designed FLC plus SMC combination over its counterpart PIC plus SMC.

A Study on the Long-Term Care Insurance System prepare for the Super-Aged Society (초고령화 사회를 대비한 노인장기요양보험제도에 관한 연구)

  • Kim, Min-Ju;Hwang, Jun-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.10
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    • pp.395-405
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    • 2019
  • Korea is undergoing a change in its population structure, due to economic development, falling birth rates and the development of health care. As the population ages, the number of elderly people who have difficulty in daily life such as dementia and paralysis increases every day. The growth of nuclear families and the increased participation of women in society make it difficult to take care of elderly people who need long-term care at home. As the social problems resulting from this have emerged as serious problems, the government enacted and implemented the Long Term Care Insurance Act to improve the quality of life for the elderly subject to long-term care and to ease the burden of family support in order to solve such problems. Therefore, the present study explores ways to improve legal and institutional aspects, and seek mental and psychological measures for the stability of old life as well as the physical health of welfare.

Monitoring Result of Rock Mass Behavior during Excavation of Deep Cavern (대심도 지하 공간 굴착시의 암반거동 - 일본 SUPER KAMIOKANDE의 사례 -)

  • Lee Hong-Gyu
    • Tunnel and Underground Space
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    • v.16 no.1
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    • pp.11-25
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    • 2006
  • The world's largest nucleon decay experiment facility is constructed at a depth of approximately 1,000 meters, in the Kamio Mine, Japan. The excavated cavern is consisted of a cylinder of 42.4 m high and a semi elliptical dome of 15.2 m high, with a bottom diameter of 40 m. The total excavation volume is approximately $69,000\;m^3$. Because of the character as a large cavern excavation in deep underground, there is many unknown factors in rock mechanics. Based on the results of rock test and numerical analysis, the monitoring of rock mass behavior accompanying progress of construction was performed by various instruments installed in the rock mass surrounding the cavern. The monitoring data was used in the study of measures for cavern stability.

Preparation and Characteristics of Poly(phenylene ether)s in Various Reaction Conditions (다양한 반응조건에 따른 폴리페닐렌에테르의 중합 특성)

  • Park, Jong-Hyun;Kim, Nam-Cheol;Kim, Yong-Tae;Nam, Sung-Woo;Kim, Young-Jun;Kim, Ji-Heung
    • Polymer Korea
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    • v.35 no.3
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    • pp.244-248
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    • 2011
  • Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was synthesized by oxidative polymerization using various Cu(I)-amine catalyst system. The effects of catalyst/monomer ratio, different amine ligand, and the content of 2,4,6-trimethylphenol (TMP) additive on the polymer yield and molecular weight were investigated by using gel permeation chromatography. The catalytic activity of various Cu-amine systems on the 2,S-dimethylphenol (DMP) polymerization was monitored and compared each other through oxygen-uptake experiment. In addition, the effect of catalyst removal using aqueous EDTA on the thermal stability of the prepared polymer was elucidated by thermogravimetric analysis.

An Application of Construction Sequence Analysis for Checking Structural Stability of High-Rise Building under Construction (초고층 건물의 시공 중 구조적 안정성 검토를 위한 시공단계해석의 적용)

  • Eom, Tae-Sung;Kim, Jae-Yo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.3
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    • pp.211-221
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    • 2009
  • With recent trends of super-tallness, atypical plan shapes and zoning constructions in high-rise buildings, a structural stability of the building under construction is arising as a key issue for design and construction plan. To ensure the structural stability under construction, the differential column shortening of vertical members, the lateral displacement of tower frames, and differential settlement of raft foundation by unbalanced distributions of a tower self-weight before the completion of a lateral load resisting system should be checked by construction sequence analysis, which should be performed by systematic combinations with structural health monitoring, construction compensation program, and construction panning. This paper presents the scheme of zone-based construction sequence analysis by using the existing commercial analysis program, to check the stability of high-rise building under construction. This scheme is applied to 3-dimensional structural analysis for a real high-rise building under construction. The analysis includes real construction zoning plans and schedules as well as creep and shrinkage effects and time-dependent properties of concrete. The simplified construction sequence and assumed material properties were continuously updated with the change on construction schedule and correlations with in-situ measurement data.