• 제목/요약/키워드: Residual Power

검색결과 727건 처리시간 0.026초

이종금속용접부 예방정비 방법에 따른 잔류응력 분포 고찰 (Investigation on the Effects of Preventive Maintenance Schemes for Dissimilar Metal Welds on the Residual Stress Distribution)

  • 송태광;최영환;박정순;정해동;오창영
    • 한국압력기기공학회 논문집
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    • 제7권4호
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    • pp.1-11
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    • 2011
  • This paper presents the effects of preventive maintenance schemes on the residual stress distributions in dissimilar metal welds. Dissimilar metal weld is known susceptible to PWSCC and thus, effective maintenance schemes to prevent PWSCC are needed. Three preventive maintenances schemes, i.e. weld overlay, MSIP and inlay weld which are widely used in nuclear power plants, are selected and their effects on welding residual stresses are investigated via finite element analyses. As results, weld overlay and MSIP were proved effective method to mitigate residual stresses and inlay weld, on the other hand, produces strong tensile residual stresses in the inner surface. Although Alloy 690 known to be resistant to PWSCC are used in inlay weld, continuous careful observation are needed since tensile welding residual stresses are key parameter for PWSCC.

화염경화 표면처리 공정에 의한 12Cr 강의 잔류응력 거동 (Behavior of the Residual Stress on the Surfaces of 12Cr Steels Generated by Flame Hardening Process)

  • 이민구;김광호;김경호;김흥회
    • 한국표면공학회지
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    • 제37권4호
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    • pp.226-233
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    • 2004
  • The residual stresses on the surfaces of low carbon 12Cr steels used as a nuclear steam turbine blade material have been studied by controlling the flame hardening surface treatments. The temperature cycles on the surfaces of 12Cr steel were controlled precisely as a function of both the surface temperature and cooling rate. The final residual stress state generated by flame hardening was dominated by two opposite competitive contributions; one is tensile stress due to phase transformation and the other is compressive stress due to thermal contraction on cooling. The optimum processing temperatures required for the desirable residual stress and hardness were in the range of $850^{\circ}C$ to $960^{\circ}C$ on the basis of the specification of GE power engineering. It was also observed that the high residual tensile stress generated by flame hardening induced the cracks on the surfaces, especially across the prior austenite grain boundaries, and the material failure virtually, which might limit practical use of the surface engineered parts by flame hardening.

압력센서의 배선을 위한 다층 박막의 지지조건 변화에 따른 잔류응력 평가 (Evaluation of the Residual Stress with Respect to Supporting Type of Multi-layer Thin Film for the Metallization of Pressure Sensor)

  • 심재준;한동섭;한근조
    • 대한기계학회논문집A
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    • 제28권5호
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    • pp.532-538
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    • 2004
  • MEMS technology applying to the sensors and micro-electro devices is complete system. These microsystems are made by variable processes. Especially, the mentallization process has very important functions to transfer the power operating the sensor and signal induced from sensor part. But in the structures of MEMS the local stress concentration and deformation are often yielded by an irregular geometrical shape and different constraint. Therefore, this paper studies the effect of supporting type and thickness ratio about thin film of the substrate on the residual stress variation when the thermal loads is applied to the multi-layer thin film fabricated by metallization process. Specimens were made from several materials such as Al, Au and Cu. Then, uniform thermal load was applied, repeatedly. The residual stress was measured by FE Analysis and nano-indentation method using AFM. Generally, the specimen made of Al induced the larger residual stress than that of made of other materials. Specimen made of Cu and Au having the low thermal expansion coefficient induces the minimum residual stress. Similarly, the lowest indentation length was measured by nano-indentation method in the Si/Au/Cu specimen. Particularly, clusters are created in the specimen made of Cu by thermal load and the indentation length became increasingly large by cluster formation.

전기분해수 살균효과 및 소독부산물 생성 특성 평가 (Disinfection effect and formation characteristics of disinfection by-product at the Electrolyzed Water)

  • 조영만
    • 상하수도학회지
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    • 제27권5호
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    • pp.547-554
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    • 2013
  • Chlorine has strong oxidizing power, also it is many advantages over other disinfectants such as the residual characteristic and economic feasibility. However, chlorine also has disadvantages such as creating disinfection by-products of chlorine as THMs. In particular, the most deadly disadvantage of chlorine is that it is extremely poisonous toxins about all alive lives. Disinfection with electrolysis water can be a very useful way Because you do not have to worry about chlorine's dangerous. In this study, we evaluated the potential as a disinfectant, across the evaluating disinfection effect and generating characteristic of by-products. The electrolyzed water could be obtained removal efficiencies of over 99.9 % the coliform by operating condition such as residence time, current density (voltage), the electrode gap. The residual chlorine be generated 10,000 mg/L in current density $1.0A/dm^2$ and residence time of 10 minutes. The residual chlorine concentration was possible to maintain a stable. The by-products generated by high concentration residual chlorine in the reactor such as trihalomethanes, haloaceticacid, chloralhydrate, haloacetonitrile were detected in less than a water quality standards. At the concentration of less than residual chlorine of 1 ppm, the chlorine disinfection by-products be generated most below the detection limit.

Indefinite sustainability of passive residual heat removal system of small modular reactor using dry air cooling tower

  • Na, Min Wook;Shin, Doyoung;Park, Jae Hyung;Lee, Jeong Ik;Kim, Sung Joong
    • Nuclear Engineering and Technology
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    • 제52권5호
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    • pp.964-974
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    • 2020
  • The small modular reactors (SMRs) of the integrated pressurized water reactor (IPWR) type have been widely developed owing to their enhanced safety features. The SMR-IPWR adopts passive residual heat removal system (PRHRS) to extract residual heat from the core. Because the PRHRS removes the residual heat using the latent heat of the water stored in the emergency cooldown tank, the PRHRS gradually loses its cooling capacity after the stored water is depleted. A quick restoration of the power supply is expected infeasible under station blackout accident condition, so an advanced PRHRS is needed to ensure an extended grace period. In this study, an advanced design is proposed to indirectly incorporate a dry air cooling tower to the PRHRS through an intermediate loop called indefinite PRHRS. The feasibility of the indefinite PRHRS was assessed through a long-term transient simulation using the MARS-KS code. The indefinite PRHRS is expected to remove the residual heat without depleting the stored water. The effect of the environmental temperature on the indefinite PRHRS was confirmed by parametric analysis using comparative simulations with different environmental temperatures.

Estimation of residual stress in dissimilar metals welding using deep fuzzy neural networks with rule-dropout

  • Ji Hun Park;Man Gyun Na
    • Nuclear Engineering and Technology
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    • 제56권10호
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    • pp.4149-4157
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    • 2024
  • Welding processes are used to connect several components in nuclear power plants. These welding processes can induce residual stress in welding joints, which has been identified as a significant factor in primary water stress corrosion cracking. Consequently, the assessment of welding residual stress plays a crucial role in determining the structural integrity of welded joints. In this study, a deep fuzzy neural networks (DFNN) with a rule-dropout method, which is an artificial intelligence (AI) method, was used to predict the residual stress of dissimilar metal welding. ABAQUS, a finite element analysis program, was used as the data collection tool to develop the AI model, and 6300 data instances were collected under 150 analysis conditions. A rule-dropout method and genetic algorithm were used to optimize the estimation performance of the DFNN model. DFNN with the rule-dropout model was compared to a deep neural network method, known as a general deep learning method, to evaluate the estimation performance of DFNN. In addition, a fuzzy neural network method and a cascaded support vector regression method conducted in previous studies were compared. Consequently, the estimation performance of the DFNN with the rule-dropout model was better than those of the comparison methods. The welding residual stress estimation results of this study are expected to contribute to the evaluation of the structural integrity of welded joints.

디젤엔진 피스톤용 SCM440의 레이저 표면경화부의 잔류응력 (Residual Stress Distribution of Laser Hardened SCM440 for Diesel Engine Piston)

  • 이동석;유웅재;김재도
    • 열처리공학회지
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    • 제8권3호
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    • pp.182-186
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    • 1995
  • SCM440, which is widely used as the diesel engine piston of vessel, has been hardened by a $CO_2$ laser with the wavelength of $10.6{\mu}m$. Laser hardening experiment has been carried out for the condition of a laser power 1kW, the travel speed between 0.4 and 1.5m/min, and a rectangular-Gaussian beam. Residual stress has been measured by using middle point technique of half value width of X-ray diffraction method. It was found that the compressive residual stress with the range between 400 and 600MHz has distributed in the laser hardening zones and the tensile residual stress between 100 and 200MHz has distributed in the boundary of hardening zones.

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축예하중을 가한 알루미늄/복합재료 동시경화 샤프트의 비틀림 피로 특성 (Torsional Fatigue Characteristics of Aluminum/Composite Co-Cured Shafts with Axial Compressive Preload)

  • Kim, Jong-Woon;Hwang, Hui-Yun;Lee, Dai-Gil
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2003년도 추계학술발표대회 논문집
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    • pp.183-186
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    • 2003
  • Long shafts for power transmission should transmit torsional load with vibrational stability. Hybrid shafts made of unidirectional fiber-reinforced composite and metal have high fundamental bending natural frequency as well as high torque transmission capability. However, thermal residual stresses due to the coefficient difference of thermal expansion of the composite and metal are developed so that the high residual stresses decrease fatigue resistance of the hybrid shafts, especially at low operating temperatures. In this work, axial compressive preload was given to the shaft in order to change the residual stresses. Static and fatigue torsional tests were performed and correlated with stress analyses with respect to the preload and service temperature.

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가동원전 잔열제거계통 배관에서의 열성층유동 해석 (An Analysis on Thermal Stratification in Residual Heat Removal System Piping of Nuclear Power Plant)

  • 박만홍;김광추;김경훈
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1597-1602
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    • 2003
  • Numerical analysis is carried out to assess the temperature distribution on the mixing tee line of Residual Heat Removal System (RHRS). In RHRS, hot and cold fluids of main and bypass piping are mixed and unmixed by the flow rate or piping layout. Thermal stratification phenomenon is a cause of major degradation on RHRS piping. According to the analysis for each operation modes, maximum temperature difference between top and bottom of piping were evaluated about 60K when the flow rate of main and bypass lines is same. Temperature difference will be decreased at the elbow on RHRS piping if the length of vertical piping is increased.

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옥테닐호박산나트륨 전분의 이화학적 특성 (Physicochemical Properties of Octenylsuccinated Corn Starch)

  • 정만곤;임번삼
    • 한국식품위생안전성학회지
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    • 제14권1호
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    • pp.84-89
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    • 1999
  • Octenylscuccinated corn starches prepared by reaction of corn starch with 1-octenylsuccinic anhydride(OSAn) and their degree of substitution (DS), reaction efficiency(RE), residual octenylsuccinic acid (OSA), and physicochemical properties were compared with those of the native corn starch. DS increased with increase of OSAn and RE was much nearly the same regardless of increased of OSAn. The content of residual of residual OSA was significantly lower than that of regulation of food additives. And as washing frequency of dispersion of the reactant was increased, the content of residual OSA of octenylsuccinated starch was decreased. Raid Visco-Analyzer initial pasting temperature and setback of octenylsuccinated starches decreased whereas peak viscosity and breakdown increased. When DS of octenylsuccinated starches increased, temperature of initial gelatinization of octenylscuccinated starches drastically decreased. The octenylsuccinated starches also formed clearer pastes. The solubility was much nearly the same regardless of increase of DS at 7$0^{\circ}C$ but the swelling power increased 1.2~1.7 times higher than that of native corn starch at 7$0^{\circ}C$. The water binding capacity of octenylsuccinated starches also decreased.

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