• Title/Summary/Keyword: 내구성 분석

Search Result 1,046, Processing Time 0.031 seconds

Effect of Pt-Co/C Cathode Catalyst on Electrochemical Durability of Membrane in PEMFC (PEMFC에서 Pt-Co/C Cathode 촉매가 고분자막의 전기화학적 내구성에 미치는 영향)

  • Sohyeong Oh;Dong Geun Yoo;Myoung Hwan Kim;Ji Young Park;Kwonpil Park
    • Korean Chemical Engineering Research
    • /
    • v.61 no.2
    • /
    • pp.189-195
    • /
    • 2023
  • As a PEMFC (Polymer Exchange Membrane Fuel Cell) cathode catalyst, Pt-Co/C has recently been widely used because of its improved durability. In a fuel cell, electrodes and electrolytes have a close influence on each other in terms of performance and durability. The effect on the electrochemical durability of the electrolyte membrane when Pt-Co/C was replaced in the Pt/C electrode catalyst was studied. The durability of Pt-Co/C MEA (Membrane Electrode Assembly) was higher than that of Pt/C MEA in the electrochemical accelerated degradation process of PEMFC membrane. As a result of analyzing the FER (Fluorine Emission Rate) and hydrogen permeability, it was shown that the degradation rate of the membrane of Pt-Co/C MEA was lower than that of Pt/C MEA. In the OCV (Open Circuit Voltage) holding process, the rate of decrease of the active area of the Pt-Co/C electrode was lower than that of the Pt/C electrode, and the amount of Pt deposited on the membrane was smaller in Pt-Co/C MEA than in Pt/C MEA. Pt inside the polymer membrane deteriorates the membrane by generating radicals, so the degradation rate of the membrane of Pt/C MEA with a high Pt deposition rate was higher than Pt-Co/C MEA. When the Pt-Co/C catalyst was used, the electrode durability was improved, and the amount of Pt deposited on the membrane was also reduced, thereby improving the electrochemical durability of the membrane.

An Analytical Study on the Durability Standard of Ground Structures Monitoring Sensors (지반구조물 계측센서의 내구연한 기준에 대한 분석적 연구)

  • Woo, Jong-Tae
    • Journal of the Society of Disaster Information
    • /
    • v.17 no.1
    • /
    • pp.53-59
    • /
    • 2021
  • Purpose & Method: The purpose of this study is the theoretical study on the durability standard of ground structures monitoring sensors. A survey on the durability criteria for construction monitoring sensors of domestic construction companies and the income tax implementation regulations, the standard years of contents such as buildings and the standards of the Public Procurement Service for construction monitoring and construction machinery were analyzed. Result: The durability criterion such as the inclination meter and the strain gauge, which are purchased from the Public Procurement Service prior to installation on the ground structure, is 8 to 10 years. Conclusion: The actual durability analysis by comparing the reliability of various monitoring sensors installed in dams at home and abroad, As a result of comprehensive study on the loss and damage rate of the maintenance monitoring sensor installed in the tunnel, the proper durability period of the built-in type monitoring sensor such as domestic pore pressure meter and earth pressure meter installed in the structure or the ground is 5 to 8 years it seems reasonable.

Performance Improvement and Durability Evaluation of Shotcrete for Permanent Tunnel Support (터널 영구 지보재로서의 숏크리트 고성능화 및 내구성 평가에 관한 연구)

  • Lee, Sang-Pil;Ryu, Jong-Hyun;Lee, Sang-Don;Jeon, Seok-Won;Lee, Chung-In
    • Tunnel and Underground Space
    • /
    • v.17 no.4
    • /
    • pp.266-284
    • /
    • 2007
  • Recently, many efforts have been made to construct the first unlined tunnel, without in-situ concrete lining, in Korea. However, the lack of reliability in the performance of shotcrete as permanent tunnel support prevented from its realization. Shotcrete has been regarded to have significant problems in field application and long term performance because of unsatisfactory strength level and durability compared to those of European countries. In this study, the high strength shotcrete satisfying compressive strength over 40 MPa and flexural strength over 4.5 MPa was developed from optimized mix design. The type of accelerators and the amount of silica fume were selected as the main factors in mixing process and the analyses were carried out up to the elapsed time of 2 years. In order to evaluate the short term durability of shotcrete, an array of laboratory test consisting of freeze-thaw, carbonation chloride penetration and permeability test was performed. For long-term durability tests, specimens have been put in an operated highway tunnel to expose them to the similar environment when they are actually used as an unlined tunnel support. From the strength and durability tests, it was found that only alkali-free based accelerator satisfied the target strength of this study and also, the developed shotcrete showed very high performance in its durability.

품질경쟁력 평가모형에서 제품 디자인의 인과관계와 디자인 경영에 관한 실증적 분석 : 한국 제조업 부문을 중심으로

  • 임채숙;임양택
    • Proceedings of the Technology Innovation Conference
    • /
    • 2004.06a
    • /
    • pp.170-213
    • /
    • 2004
  • 생산자 중심에서 소비자 중심으로의 경영 패러다임이 변화함에 따라, 이제 디자인 경영(design management)의 시대가 도래하였다 즉, 제반 기능의 활동이 독립적이고 순차적으로 이루어지는 기존 경영방식(즉, 제품 개발 $\rightarrow$ 제품 디자인 $\rightarrow$ 제조 $\rightarrow$ 마케팅 $\rightarrow$ 판매)과는 달리, 디자인 경영은 디자인을 중심으로 제반 기능간의 통합과 조정을 이룬다. 이 결과, 디자인 경영은 조직간의 커뮤니케이션을 활성화시키며 소비자의 추상적인 욕구가 구체적으로 상품에 표현되도록 노력한다. 이렇게 함으로써, 디자인 경영은 기업 이미지 창조의 역할을 적극적으로 수행하는 것이다. 이와 같은 소비자 중심의 경영은 과거 제품의 판매(sales)지향적이던 기업 활동을 소비자와의 관계(relationship)지향적으로 변화시키고 있다. 본 연구의 분석 목적은 제품 디자인을 품질경쟁력의 결정요인으로서 포함시켜 품질경쟁력의 평가모형을 개발하고 품질경쟁력의 결정요인 및 상관관계와 품질함수를 추정함으로써 제품 디자인 및 디자인 경영의 기능적 역할을 규명하고 디자인 경쟁력 수준을 평가 및 측정할 수 있는 모형을 정립함과 동시에 이를 제고할 수 있는 정책방향을 제시하는 것이다. 이로써, 본 연구는 신상품의 개발과정에서 어떻게 제품 디자인이 연구개발, 제조, 마아케팅, 판매 등의 제반 기능들과 상호 작용하며 이들 기능들의 통합과 조정을 추구할 수 있는가를 보여주는 디자인 경영의 이론적 기초를 제공하고자 함이다. 상기와 같은 연구목적과 분석목표를 위하여, 한국 제조업 부문의 400개 표본기업에 대하여 소정의 설문조사를 통하여 추출된 측정변수들을 기초로 품질경쟁력의 결정요인을 분석하고 품질경쟁력 지수를 도출하여 산업부문별 및 제품유형별로 비교하였으며, 품질함수를 추정하였다. 전술한 분석결과를 토대로, 디자인 경영이론의 기초를 제공하기 위한 시도로서 제품 디자인의 파급효과와 인과관계에 대한 가설검정을 실시하였다. 본 연구의 분석 결과는 다음과 같이 요약될 수 있다. (1) 품질경쟁력의 결정요인으로서 주요 제품들의 기능성, 기본 성능, 제품성과의 기술적 성취도, 제품 수명(내구성), 신뢰성, 핵심 기술력, 사용 편의성, 서비스 편의성, 생산 용이성, 제품 디자인의 우수한 정도가 a=0.01 수준 하에서 유의적으로 추정되었다. 이들 변수들 중에서 품질경쟁력에 가장 큰 영향을 미치는 측정변수는 제품의 기본 성능, 수명(내구성), 신뢰성, 제품 디자인의 순서로 추정되었다. 이것은 한국 제조업이 아직 산업 디자인이 품질경쟁력에 크게 영향을 미치는 성숙단계에 이르지 못하였음을 의미한다. (2) 제품 디자인에게 영향을 끼치는 유의적인 변수는 연구개발력, 연구개발투자 수준, 혁신활동 수준(5S, TPM, 6Sigma 운동, QC 등)이며, 제품 디자인은 우선 품질경쟁력을 높여 간접적으로 고객만족과 고객 충성을 유발하는 것으로 추정되었다. 상기의 분석결과로부터, 본 연구는 다음과 같은 정책적 함의를 도출하였다. 첫째, 신상품 개발과 혁신을 위한 포괄적인 연구개발 프로젝트를 품질 경쟁력의 주요 결정요인(제품의 기본성능, 신뢰성, 수명(내구성) 및 제품 디자인)과 연계하여 추진해야 할 것이다. 둘째, 기업은 디자인 경영 마인드 제고와 디자인 전문인력 양성을, 대학은 디자인 현장 업무를 통하여 창의력 증진과 기획 및 마케팅 능력 교육을, 정부는 디자인 기술개발 및 디자인 교육지원의 강화를 통하여 각각 디자인 경쟁력$\rightarrow$품질경쟁력을 제고시켜야 할 것이다.

  • PDF

Evaluation on Durability of High Performance Concrete with Expansive Additive and Shrinkage Reducing Admixture (팽창재와 수축저감제를 사용한 고성능 콘크리트의 내구성 평가)

  • Koh, Kyung-Taek;Kang, Su-Tae;Park, Jung-Jun;Ryu, Gum-Sung
    • Journal of the Korea Concrete Institute
    • /
    • v.18 no.2 s.92
    • /
    • pp.205-211
    • /
    • 2006
  • The objective of this study was to evaluate the durability of low shrinkage high performance concrete(LSHPC), which was combined with expansive additives and shrinkage reducing admixtures. We tested for not only LSHPC but also high performance concrete(HPC) and normal concrete(NC) to be compared with the durability of LSHPC. HPC was made in the same water-binder ratio of LSHPC without expansive additives and shrinkage reducing admixture. As a result, it was found that LSHPC had higher compressive and tensile strength than that of HPC. LSHPC showed more excellent performance than HPC and NC in the case of resistance to chloride ion penetration and resistance to carbonation and also showed nearly 100 durability factor in the freeze-thawing test with 500 cycles. From the examination about the watertightness and the pore distribution, it was found that the durability of LSHPC was improved because its hardened cement paste is organized closer. So we can conclude that when LSHPC is applied to structures in field, it is possible to reduce the shrinkage and crack in concrete and improve the durability.

Durability Evaluation of Cathode Open-type Proton Exchange Membrane Fuel Cells Stacks (Cathode 개방형 고분자연료전지 스택 내구성 평가)

  • Yoo, Donggeun;Kim, Hyeonsuck;Oh, Sohyeong;Park, Kwon-Pil
    • Korean Chemical Engineering Research
    • /
    • v.60 no.1
    • /
    • pp.12-19
    • /
    • 2022
  • Cathode open-type PEMFC (Proton Exchange Membrane Fuel Cells) stacks, which are widely used in small transport-type PEMFC, have a problem with poor durability. Through the accelerated durability test of the 13-cell PEMFC stack, we tried to find the cause of the degradation of the stack and to contribute to the improvement of the durability of the cathode open stack. A hydrogen/air boundary is formed during start-up/shut-down (SU/SD) due to the structural problem of the cathode open stack in which the cathode is open to the atmosphere and it is difficult to maintain airtightness, thereby deteriorating the cathode. In this study, it was possible to evaluate the durability in a relatively short time by reducing the 54% of the initial performance by repeating SU/SD 1,800 times on the cathode open stack. After dismantling the stack, each cell was divided into two and the performance was analyzed. Overall, the anode outlet MEA, which facilitates air inflow, showed more severe electrode deterioration than the inlet MEA, confirming that the hydrogen/air boundary formation during SU/SD is the main cause of degradation.

The Estimation of Durability Factor of Deteriorated Jointed Concrete Pavement Using Image Analysis Test (화상분석 실험을 이용한 열화된 줄눈콘크리트 포장의 내구성 지수 평가)

  • Choi, Pan-Gil;Kim, Yong-Gon;Yun, Kyong-Ku;Kwon, Soo-Ahn
    • Journal of the Korean Society of Hazard Mitigation
    • /
    • v.9 no.5
    • /
    • pp.31-38
    • /
    • 2009
  • The primary objective of this study was to estimate the deterioration degree of jointed concrete pavement which was major concrete pavement type in Korea. First of all, visual survey of concrete pavement was performed to observe deterioration types. In the result of visual survey, the majority of concrete pavement deterioration was investigated in joint area. It is appeared that most of the distresses are durability cracking and joint distress. Second, concrete core specimens were taken from eight locations including good section (4 locations) and bad section (4 locations) based on visual survey. The deterioration reasons of concrete pavement were analyzed with ultrasonic pulse velocity test, splitting tensile strength test, and image analysis for concrete core specimens. Among the image analysis test result for 21 concrete core specimens, only two specimens satisfied the Kansas DOT criteria of spacing factor, $250\;{\mu}m$, and the remains of 19 specimens were estimated to be above $250\;{\mu}m$. The durability factor of concrete was estimated very low. As a result, it was analyzed that the main deterioration reason of the deteriorated jointed concrete pavement was to be freezing and thawing damages.

탈피복에 공급하는 사용후핵연료봉 절단방식 분석

  • Kim, Yeong-Hwan;Park, Geun-Il;Lee, Jeong-Won;Lee, Yeong-Sun;Lee, Do-Yeon;Kim, Su-Seong
    • Proceedings of the Korean Radioactive Waste Society Conference
    • /
    • 2011.10a
    • /
    • pp.161-162
    • /
    • 2011
  • 유압동력사용 전제하에, 기계식탈피복을 고려하지 않을 때는 전단방식이 가장 유리함을 알 수 있다. 절단방식은 전단방식에 비해서 낮은 생산성이 단점이나, 높은 원형도의 연료봉 절단면이 요구되거나, 비산에 의한 칩 분리, 쿨링(cooling) 장치를 보완하면 절단방식이 유리하다. 또한 수평식 슬릿장치는 커팅 블레이드의 낮은 내구성으로 생산성이 낮은 것이 단점이나 내구성이 강한 공구를 사용하여 처리 속도를 향상한다는 전제에서 실험적 검증의 확보, 그리고 별도의 복잡한 펠릿/헐 분리장치를 보완하면 수평식 슬릿 방식이 유리하다.

  • PDF

Affecting Analysis of Air Content on the Freeze-Thaw Durability of Concrete (콘크리트의 동결융해 내구성에 공기량이 미치는 영향 분석)

  • Lee, Beung-Duk;Kim, Hyun-Joong;Kang, Hye-Jin
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2008.04a
    • /
    • pp.565-568
    • /
    • 2008
  • Domestic area of most be happened chloride deicer damage. Because daily mean temperature is below 0$^{\circ}C$ from the area of domestic most. Concrete durability influence Air Content. Presently, We used to AE(air-entraining agent) for increase freeze-thaw durability. So, on concrete Air Spacing ratio used $200{\mu}m{\sim}230{\mu}m$ in Canada and under $250{\mu}m$ in Japan institution. Use of Air content has been and will continue to be a major part of concrete durability and scaling. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. The prepared optimum mix concrete in this study show that freeze-thaw and scaling resistance of Non-AE(air content 1.5%) and AE (air content 4.5%, 7.2%). Solution concentrations of deicing agent were good result, and the pore system and change of hydration products is not difference comparing before freeze-thaw test.

  • PDF