• 제목/요약/키워드: Competitive stress

검색결과 93건 처리시간 0.027초

터널 지보재로서 케이블볼트의 성능평가에 관한 수치해석적 연구 (Numerical Analysis on the Performance Evaluation of Cablebolts as Tunnel Supports)

  • 박연준;박준형
    • 터널과지하공간
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    • 제22권2호
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    • pp.130-143
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    • 2012
  • 케이블볼트는 장공의 볼트가 필요한 경우나 대용량의 보조지보재로 사용되어졌으나, 지보능력의 상승과 다루기가 용이하다는 점에서 경쟁력을 갖추게 되었다. 다양한 연구로부터 얻어진 실험결과에 근거하여 길이와 고정조건을 변화시켜가며 케이블볼트의 성능을 수치해석적으로 분석하였다. 지보효과는 변위와 숏크리트 응력을 바탕으로 평가하였다. 케이블볼트에 긴장을 가하지 않고 그라우팅만 하였을 때에는 록볼트에 비해 지보효과가 떨어졌다. 그러나 긴장이 가해졌을 경우의 지보능력은 록볼트를 대신하기에 충분하였다. 케이블볼트의 긴장 후에 즉시 그라우팅을 시행하면 지보능력이 오히려 감소되지만 굴착면의 영향을 벗어난 후에 그라우팅을 수행하면 지보능력도 감소되지 않고 장기적인 안정성도 확보할 수 있을 것으로 판단되었다. 주 지보재로서 케이블볼트를 현장에 적용하기 위해서는 보다 다양한 조건에서의 실험실 시험과 현장 시험 등을 포함한 연구가 수행되어야 할 것이다.

STS429L 겹침 용접부의 파단 특성에 관한 연구 (A Study on Characteristic of Fracture in Lap Joint Welded STS429L)

  • 최동순;김재성;김현재;이보영
    • Journal of Welding and Joining
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    • 제27권5호
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    • pp.49-54
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    • 2009
  • Recently, a demand of ferritic STS is increasing rapidly in automobile exhaust system. Exhaust manifolds are the part nearest to the engine so that the material is exposed to high temperature exhaust gas. Excellent heat resistant properties, especially high temperature strength, thermal fatigue resistance and high corrosion resistance are necessary for these parts. STS429L contains 15 weight percent of Cr and low Mo, so has good price competitive. And it has excellent high temperature strength and corrosion resistance, so receives attentions as material that applying to exhaust manifold. In tensile test of lap joint welded STS 429L, most of specimens are failed in base metal, but occurs brittle fracture in weld metals at some specimens in the face of good welding conditions. In the process of tensile test, lap joint welded STS429L specimens are transformed locally. The brittle fracture occurs that local transforming area exists in weld metals. But, butt welding specimens made by same materials showed ductile fracture in tensile test and bending test. In this study, suppose the reason of brittle fracture is in the combined local transform and tensile stress, through analysis of bead geometry, evaluate geometrical factor of brittle fracture in lap joint welded STS429L.

바이오디젤 원료 작물 품종 개량과 생명공학기술 응용 (Biodiesel: Oil-crops and Biotechnology)

  • 노경희;박종석
    • Applied Biological Chemistry
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    • 제50권3호
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    • pp.137-146
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    • 2007
  • 지구 온난화의 주 원인인 온실가스의 배출을 감소시키기 위해서 바이오연료에 대한 필요성 및 중요성이 제기되어 왔다. 이미 유럽을 중심으로 오래전부터 바이오디젤 연료에 대한 연구가 시작되어 왔으며 지금은 상용화 단계에 접어들고 있는 반면, 국내 바이오디젤 연료에 대한 연구 수준은 이제 시작단계에 불과한 실정이다. 바이오디젤 연료로 사용가능한 유지작물의 지방산 조성에 따라 자동차 엔진 성능이 저하될 수 있다는 문제가 제기되었고, 이를 해결하고자 표준화된 바이오디젤 품질 규격서가 마련되어졌다. 유럽에서 마련된 바이오디젤 규격에 의하면 올레인산 함량이 높은 기름이 바이오디젤 연료로 적합하며, 유채기름이 다른 유지작물의 기름에 비하여 바이오디젤 연료에 적합하다고 알려져 있다. 따라서 국내 유지작물의 바이오디젤 연료화를 위한 품질 개량과 생산량 증대를 위해 생명공학기술을 이용한 품종 개량에 관한 연구 전략에 대해 고찰하였다.

외식사업 신규창업을 위한 사업계획서 작성방법 사례와 투자경제성 분석에 관한 연구 (Case Studies on Preparing a Business Plan for the Foundation of Food Service Business and Analysis of Investing Economy.)

  • 홍기운
    • 한국조리학회지
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    • 제3권
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    • pp.385-421
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    • 1997
  • This study was performed as placing stress on business plan preparation and investing economy analysis centered to cases upon presenting the premises of study for new foundation of food service business. The summarized results are as follows: 1. In the aspect of carrying out process of practical project, establishing the promotion strategy, the facility project program, the menu program, the facility and furniture program, organization & manning schedule, the business operation schedule, review of all laws & provisions and the allout promotion schedule in order were deployed. 2. Analysis of investing economy for review of profitability 1) In case of investment, excluding 600million for the real setate lease among the total investment of 1billion, it was required by 161, 235, 000 for interior project, 161, 110, 000 for facility & equipment, 19, 235, 000 for fittings, 27, 600, 000 for menu plate & uniform, 27, 600, 000 for furniture, 13, 800, 000 for sign article. 2) In case of loss & profit presumed the annual turnover is to be 1, 115, 856, 000 the contigent profit(before tax) is to be 148, 966, 000 which is 13.3% in comparson to the sales amount and the net profit(after tax) for this term s to be 104, 276, 000 which is 9.3% against the sales and the profitable ratio to the equity investment( 500 million) is 20.9% and it satisfies 20% of the premises of study. 3) In case of the payback period will be approximately two(2) years which indicated within three(3) years that is standard of new project evaluation term of ordinary enterprise. 4) In case of internal rate of return it will be 21.5% which is favorable profitability as taking into account of 15% that is standard of new project evaluation by ordinary enterprise based on general downtown money interest. That the investing value of Happy Day profitability is hinted as it is sufficient enough as the case under this study based upon such results and considered that securing supremacy is competitive power in case of commitment will be possible.

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부산지역 백화점의 소비자 특성 분석 (Analysis of Consumer Characteristics of Department stores in Pusan)

  • 이경희;안소현;김석주
    • 마케팅과학연구
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    • 제8권
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    • pp.403-427
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    • 2001
  • 본 연구는 다양한 소매업태 중에서 고품격 차별화 경영으로 고급 소매업으로서 부동의 자리를 유지하고 있는 국내 백화점 사업부문 중 부산지역에 위치한 백화점의 소비자 특성에 대한 분석을 통하여 급격한 경쟁환경의 변화와 소비자 변화에 대응하고자 하는 목적에서 이루어졌다. 이를 위해 현대백화점 고객을 대상으로 첫째, 고객의 백화점 이용 실태, 둘째, 주요 경쟁 점 대비 현대 백화점 부산접의 경쟁력, 셋째, 경쟁환경 변화가 현대백화점 부산접에 미치는 영향 등을 통해 부산지역 백화점의 소비자 특성을 파악하였다. 이러한 연구는 백화점 소비자 특성에 대한 이해를 도움으로써 백화점의 마케팅과 판촉전략 수립을 위한 기초자료로 사용될 수 있으며 백화점과 타 소매업태들과의 경쟁에 대한 전략적 시사점을 제공해 줄 수 있을 것으로 여겨진다.

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디자인 체험전시관의 전시공간구성 및 연출에 관한 연구 - 어린이 체험관의 아이템 선정과 대안제시 - (A Study on Space Plan and Production for the Design Exploratorium - The Selection of Items and the Presentation of Alternative Plans in a Children′s Design Exploratorium -)

  • 고도재;임채진
    • 한국실내디자인학회:학술대회논문집
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    • 한국실내디자인학회 2003년도 춘계학술발표대회 논문집
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    • pp.104-111
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    • 2003
  • Today, design is considered to have competitive power for a county, so there has been various efforts such as education, publicity and development, etc. Design has long been a national material, and Korea Institute of Design Promotion(KIDP) was inaugurated for the purpose of education, publicity, development and the management, public ownership, support of the contents. Laying stress on the results, however, the design education for children which would be the heart of a world design power is short of both investment and systematic study of education. Now that the design education for children is being active, the cultural spaces are needed to transform the current system focused on schooling and textbooks into the participating, experiential ones by the interesting, educational, and entertaining presentation. The children design exploratorium should make children have their own feelings, and present communicative methods considering children's cognition and behaviors. So, in this study, I'd like to analyze characteristics of the participating and experiential exhibition, and present a children design exploratorium as an alternative plan by the application of adequate methods to the exhibition medium, and the analysis of current exploratoriums' features case by case. The children design exploratorium is the place to maximize the educational effect of design by children's easier and exciting participation, which would offer an unique exhibition place for children to comprehend designs. In this study, on the basis of the alternative presentation of children design exploratoriums, I would refer to the future direction of the 21st century pavilions, the search for the exhibition items for active design education, and the contribution to practical plans.

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Increasing the Triacylglycerol Content in Dunaliella tertiolecta through Isolation of Starch-Deficient Mutants

  • Sirikhachornkit, Anchalee;Vuttipongchaikij, Supachai;Suttangkakul, Anongpat;Yokthongwattana, Kittisak;Juntawong, Piyada;Pokethitiyook, Prayad;Kangvansaichol, Kunn;Meetam, Metha
    • Journal of Microbiology and Biotechnology
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    • 제26권5호
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    • pp.854-866
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    • 2016
  • The production cost of biodiesel from microalgae is still not competitive, compared with that of petroleum fuels. The genetic improvement of microalgal strains to increase triacylglycerol (TAG) accumulation is one way to reduce production costs. One of the most promising approaches is the isolation of starch-deficient mutants, which have been reported to successfully increase TAG yields. To date, such a stable mutant is not available in an oleaginous marine microalga, despite several advantages of using marine species for biodiesel production. Algae in the genus Dunaliella are known to tolerate high salt concentration and other environmental stresses. In addition, the cultivation processes for large-scale outdoor commercialization have been well established for this genus. In this study, Dunaliella tertiolecta was used to screen for starch-deficient mutants, using an iodine vapor-staining method. Four out of 20,016 UV-mutagenized strains showed a substantial reduction of starch content. A significantly higher TAG content, up to 3-fold of the wild-type level, was observed in three of the mutants upon induction by nitrogen depletion. The carotenoid production and growth characteristics of these mutants, under both normal and oxidative stress conditions, were not compromised, suggesting that these processes are not necessarily affected by starch deficiency. The results from this work open up new possibilities for exploring Dunaliella for biodiesel production.

The use of the strain approach to develop a new consistent triangular thin flat shell finite element with drilling rotation

  • Guenfoud, Hamza;Himeur, Mohamed;Ziou, Hassina;Guenfoud, Mohamed
    • Structural Engineering and Mechanics
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    • 제68권4호
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    • pp.385-398
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    • 2018
  • In the present paper, we offer a new flat shell finite element. It is the result of the combination of a membrane element and a bending element, both based on the strain-based formulation. It is known that $C^{\circ}$ plane membrane elements provide poor deflection and stress for problems where bending is dominant. In addition, they encounter continuity and compliance problems when they connect to C1 class plate elements. The reach of the present work is to surmount these problems when a membrane element is coupled with a thin plate element in order to construct a shell element. The membrane element used is a triangular element with four nodes, three nodes at the vertices of the triangle and the fourth one at its barycenter. Each node has three degrees of freedom, two translations and one rotation around the normal. The coefficients related to the degrees of freedom at the internal node are subsequently removed from the element stiffness matrix by using the static condensation technique. The interpolation functions of strain, displacements and stresses fields are developed from equilibrium conditions. The plate element used for the construction of the present shell element is a triangular four-node thin plate element based on Kirchhoff plate theory, the strain approach, the four fictitious node, the static condensation and the analytic integration. The shell element result of this combination is robust, competitive and efficient.

서비스 판매요원의 통제, 반응 그리고 성과의 관계 (The Relationships between Control Systems, Reactions, and Performances of Customer-Contact Service Employees)

  • 김효순
    • 정보학연구
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    • 제2권2호
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    • pp.69-88
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    • 1999
  • 고도의 경쟁환경속에서 고객의 기대에 맞춰 혹은 그 이상으로 서비스를 전달할 수 있는 능력이 있는 서비스조직만이 생존 및 성장할 수 있다. 유형의 재화와 달리 서비스 재화는 무형성, 생산과 소비의 비분리성, 서비스품질의 이질성, 그리고 소멸성이라는 독특한 특징을 가지고 있으며, 서비스요원에 대한 상대적 의존도가 높다. 하지만 이러한 측면을 반영하여 서비스조직의 효율적인 관리에 관한 연구는 미흡한 실정이다. 따라서 본 연구는 서비스특성에 따라 서비스조직의 통제시스템이 어떻게 결정되며, 각 통제유형에 따라 서비스요원의 반응(역할스트레스)과 성과(서비스품질)가 결정되는 베커니즘을 통합적 개념틀을 통하여 제안하는 것을 목적으로 한다. 구체적으로 살펴보면, 먼저 서비스 및 서비스품질의 개념 및 중요성을 기술하고, 다음으로 서비스조직의 통제시스템에 대한 통합적 개념틀을 중심으로 (1)서비스 특성에 따른 통제시스템, (2)통제유형에 따른 서비스요원의 반응, (3)통제유형과 고객에 의하여 지각된 서비스품질과의 관계, 그리고 (4)서비스요원의 반응과 서비스품질의 관계의 네 가지 측면에 대하여 각각의 제안가설들을 제시한다. 본 연구의 마지막에는 전반적 논의와 미래를 위한 연구 방향들을 제시하고 있다.

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A New Concept for Efficient Sensitivity Amplification of a QCM Based Immunosensor for TNF-α by Using Modified Magnetic Particles under Applied Magnetic Field

  • Bahk, Yeon-Kyoung;Kim, Hyung-Hoon;Park, Deog-Su;Chang, Seung-Cheol;Go, Jeung-Sang
    • Bulletin of the Korean Chemical Society
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    • 제32권12호
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    • pp.4215-4220
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    • 2011
  • This study introduces a new concept for a simple, efficient and cheap sensitivity amplification of a Quartz Crystal Microbalance (QCM) based immunosensor system for the detection of tumor necrosis factor-alpha (TNF-${\alpha}$, TNF) by using an in-built magnetic system. The frequency shift due to the applied magnetic field was successfully observed on magnetic particles labeled detection antibodies, anti-human TNF-${\alpha}$, which were bound to the immunologically captured TNF-${\alpha}$ on the gold coated quartz crystals. In the present system, the magnitude of frequency shift depends on both the strength of magnetic field and the amount of target antigen applied. Significant signal amplification was observed when the additional built-in residual stress generated by the modified magnetic particles under the magnetic field applied. Used in conjunction with a sandwich type non-competitive immunoassay format, the lower detection limit was calculated to be 25 $ngmL^{-1}$ and showed good linearity up to TNF-${\alpha}$ concentrations as high as 2.0 ${\mu}gmL^{-1}$. The sensitivity, most importantly, was improved up to 4.3 times compared with the same QCM system which was used only an antigen-antibody binding without additional magnetic amplification.