• Title/Summary/Keyword: 기술 안정성

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Structural Stability Study on the Location and Installation form of H-beam Backfill Applied to Top-Down Construction Method (역타공법에 적용되는 뒷채움재 위치 및 설치 형태에 대한 구조 안정성 연구)

  • Shim, Hak-Bo;Jeon, Hyun-Soo;Seok, Won-Kyun;Park, Soon-Jeon
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.05a
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    • pp.179-179
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    • 2021
  • Top-Down construction method is a method of connecting a beam to a column and using a strut to support earth retaining walls. This method has the advantage of reducing the process of underground construction by reducing the work of installation. Recently, there are a lot of cases of damage and defect occurring in H-beam backfill applied to Top-Down construction method and the concrete slab supporting H-beam backfill. For this, appropriate methods were suggested through finite element analysis of the position and installation form of the H-beam backfill.

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Compression Test of a TBM Thrust Jack for Validating Buckling Stability (TBM 추진잭의 좌굴 안정성 검토를 위한 압축시험)

  • Mun-Gyu Kim;Min-Gi Cho;Jung-Woo Cho;Han-Young Jeong
    • Tunnel and Underground Space
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    • v.33 no.5
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    • pp.339-347
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    • 2023
  • As the jacks provide a thrust force on the inclined surface, bending deformations by a side force occur in the pedestal and rod parts. This can induce disorder or degradation of the thrust module, buckling stability on the inclined compression condition should be clarified to secure the reliability of shield TBM. For analyzing the stability, a buckling testing method for hydraulic cylinder was investigated and compression testing system was installed. Before the test, a numerical analysis was conducted to check the stress concentration parts. The maximum allowable force was loaded on the cylinder specimen at 0 degree surface condition as a preliminary test. After the test, plastic deformations or hydraulic leakage was not observed. The static stability of it was verified at 0 degree condition.

Preparation and UV-Protective Properties of Chitin and Chitosan Particles (키틴 및 키토산 미립자의 제조 및 자외선 차단 특성)

  • Cho, Suk-Hyung;Kim, Young-Jun
    • Proceedings of the KAIS Fall Conference
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    • 2010.11b
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    • pp.1005-1009
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    • 2010
  • 자외선을 막아주고 피부에 안정한 자외선 차단성을 갖는 고분자 미립자를 키틴 및 키토산 미립자에 p-amino benzoic acid(PABA), parsol MCX, parsol 1789를 공유결합시키거나 캡슐화시켜 제조하였다. 자외선 차단성을 갖는 고분자 미립자의 자외선 차단성은 우수하였다. 그리고 피부에 대한 안정성과 독성을 in vivo로 평가한 결과 기존의 화학 자외선 흡수제 보다 안정하였다.

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A Study on the Evaluation of Cosmetic Stability of Broccoli Extracts (브로콜리 추출물의 화장품 안정성 평가 연구)

  • Yong-Shin Kim;Seon-Hee You
    • Journal of the Korean Applied Science and Technology
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    • v.40 no.5
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    • pp.1065-1071
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    • 2023
  • This study compared antioxidant activity through DPPH radical scavenging activity of broccoli extract, low temperature (5℃ or less), and high temperature (50℃ or higher) storage conditions. As a result of the experiment, high DPPH radical scavenging activity of 95.5% was confirmed at 1% concentration of broccoli extract, and antioxidant power was maintained at a high level even under storage conditions due to temperature changes. Even cream containing 5% broccoli extract has been confirmed to maintain safety and stability in both preparation stability, discoloration and odor change, pH, and primary adhesion tests. Through these studies, it has been confirmed that broccoli extract is a safe and effective cosmetic material for the skin through high antioxidant activity and antioxidant power maintenance due to temperature changes.