• Title/Summary/Keyword: Inspection Flow

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Supplementation of Flow Accelerated Corrosion Prediction Program Using Numerical Analysis Technique (수치해석 기법을 활용한 FAC 예측 프로그램 보완)

  • Hwang, Kyeong-Mo;Jin, Tae-Eun;Park, Won;Oh, Dong-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.4
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    • pp.437-442
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    • 2010
  • Flow-accelerated corrosion (FAC) leads to thinning of steel pipe walls that are exposed to flowing water or wet steam. From experience, it is seen that FAC damage to piping at fossil and nuclear plants can result in outages that require expensive repairs and can affect plant reliability and safety. CHECWORKS have been utilized in domestic nuclear plants as a predictive tool to assist FAC engineers in planning inspections and evaluating the inspection data so that piping failures caused by FAC can be prevented. However, CHECWORKS may be occasionally ignore local susceptible portions when predicting FAC damage in a group of pipelines after constructing a database for all the secondary side piping in nuclear plants. This paper describes the methodologies that can complement CHECWORKS and the verifications of CHECWORKS prediction results using numerical analysis. FAC susceptible locations determined using CHECWORKS for two pipeline groups of a nuclear plant was compared with determined using the numerical-analysis-based FLUENT.

Recent Research Trend in Lateral Flow Immunoassay Strip (LFIA) with Colorimetric Method for Detection of Cancer Biomarkers (암 바이오마커 검출용 비색법 기반 측면 흐름 면역 크로마토그래피 분석법(LFIA) 스트립의 최신 연구 동향)

  • Lee, Sooyoung;Lee, Hye Jin
    • Applied Chemistry for Engineering
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    • v.31 no.6
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    • pp.585-590
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    • 2020
  • Successful early diagnosis of cancer diseases such as lung, prostate, liver and adrenocortical carcinoma is a key step in determining the cost of treatment, survival rate, and cure rate. Most of current cancer diagnosis systems including biopsy, computed tomography (CT), positron emission tomography (PET)-CT, magnetic resonance imaging (MRI), ultrasonography, etc., require expensive and complicated equipment with highly trained human resources. Global medical and scientific communities have thus made numerous efforts on developing effective but rapid disease management system via introducing a wide spectrum of point-of-care medical diagnosis devices. Among them, a lateral flow immunoassay strip technique has gained a great attention due to many advantages such as cost-effectiveness, short inspection time, and user friendly accessibility. In this mini-review, we will highlight recent research trend on the development of colorimetry based LFIA strips for cancer diagnosis and discuss the future research direction and potential applications.

Survey Research on Thermal Situation of Office Buildings (사무소 건축물의 단열상황에 관한 조사연구)

  • Jung, Ui In;Kim, Bong Joo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.3
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    • pp.145-152
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    • 2013
  • This study is to evaluate the thermal insulation of the curtain wall of the buildings constructed since the 1990s to the buildings currently under construction in 2011 and to provide the basic data for repairing and reinforcing and designing the thermal insulation. To this effect, the temperature difference by part was analyzed through measuring the inside and outside surface temperature of the curtain wall of the office building, and thereafter, the conditions of the thermal insulation and the thermal bridge part were examined. The result of the study is as follows; Not only in the winter season when the temperature difference between the indoor-outdoor is over $20^{\circ}C$, but also in the summer season when there is a small temperature difference, the temperature difference between the inside and outside of the frame is $2^{\circ}C{\sim}4^{\circ}C$ equally. Under such conditions as stated above, the thermal bridge occurred, which resulted from the heat flow of the steel frame part (mullion, transom), and therefore, the reinforcement of the thermal insulation is considered to be needed.

Hydration and Compressive Strength of High-volume Fly Ash Cement Paste (하이볼륨 플라이애시 시멘트 페이스트의 수화 및 압축강도 특성)

  • Hwang, Chul-Sung;Moon, Eun-Jin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.5
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    • pp.156-162
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    • 2017
  • Recently, researches on High-Volume Fly ash Cement(HVFC), which is replacing high portion of cement to fly ash, have been actively conducted to reduce $CO_2$ formation. Though HVFC has various advantages, low strength development in early ages is pointed out as the biggest problem in the application of fly ash. In order to overcome such limitations, this study investigated the hydration and compressive strength characteristics of HVFC paste depending on the fly ash content with the mixing ratio varying from 0 to 80 %. Experimental results show that the HVFC paste with low water-binder ratio can overcome the limitation of low compressive strength at early ages. Also, from the result of heat flow delay, 50 % of fly ash weight ratio was the critical point of the filler effect.

Consolidation Model and Numerical Analysis for Soft Clay Ground Considering Characteristics of Material Function (물질함수특성을 고려한 연약 점토지반의 압밀모델 및 수치해석)

  • Jeon, Je-Sung;Yi, Chang-Tok;Lee, Song
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.2
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    • pp.123-136
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    • 2004
  • Terzaghi's one-dimensional consolidation theory has some important assumption, which can't be applicable to predict the behavior of soft clay ground. Especially, predictions using infinitesimal strain and linear material function related with permeability can give rise to mistake in comparison with the result of real behavior in site. For this reason, Gibson et al. established a rigorous formulation for the one-dimensional nonlinear finite strain consolidation theory, which can consider non-linearity of material function. But it is difficult to apply this theory to predict the behavior of common soft clay ground with vertical drain. In this study, consolidation model which can consider the vertical and horizontal flow of a fully saturated clay layer, self-weight of soil and nonlinear characteristics of compressibility and permeability are derived. Numerical analysis scheme, which can be applied to consolidation analysis by derived consolidation model in this study was developed. The characteristics of material function were examined using laboratory testing such as standard consolidation test, Rowe-cell test and modified consolidation test.

A Study on the Ultrasonic Inspection Method in High Attenuation Welds using Minimization-Polarity Threshold Algorithm (최소극 문턱치 알고리즘을 이용한 고감쇠 용접부에서 초음파 검사방법에 관한 연구)

  • Koo, Kil-Mo;Park, Chi-Seung;Choi, Jong-Ho;Ko, Duck-Young
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.37 no.3
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    • pp.30-36
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    • 2000
  • In this paper, an ultrasonic testing method for inspection of high attenuation welding area using the minimum Polarity threshold algorithm which combines the minimum amplitude selection algorithm and polarity threshold algorithm is suggested to increase the signal to noise ratio of the flow signal. In order to confirm the usefulness of the suggested algorithm, experiments were performed using four probes and standard specimens following the ASME Xl Code. As a result, scattering signals were observed from the SE(safe end) and CCSS (centrifugal casting stainless steel) materials due to the microstructural characteristical, and the detectability was reduced due to the highly attenuated signal from the weldment area, but it was conformed that using the suggested algorithm, the signal to noise ratio increased about 2.6.

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Influence of Blended Activators on the Physical Properties of Alkali-activated Slag Mortar (알칼리 활성화 슬래그 모르타르의 특성에 미치는 혼합 활성화제의 영향)

  • Kim, Tae Wan;Park, Hyun Jae;Seo, Ki Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.6
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    • pp.26-33
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    • 2012
  • This paper reported on the effect of blended activator on the physical properties of alkali-activated slag mortar. Five different activators(caustic alkalis) were used: sodium hydroxide(NaOH, A Case), calsium hydroxide($Ca(OH)_2$, B Case), magnesium hydroxide($Mg(OH)_2$, C Case), aluminum hydroxide($Al(OH)_3$, D Case), and potassium hydroxide(KOH, E Case). We blended five caustic alkalis with sodium carbonate($Na_2CO_3$). The dosage of five caustic alkalis was 3M and sodium carbonate was 1M, 2M and 3M. The result of flow and setting time was decrease as the dosage of sodium carbonate increase. But the compressive strength was increase as the dosage of sodium carbonate increase. It was shown that there is a good effect of blended caustic alkalis with sodium carbonate in alkali-activated slag mortar.

Study on Performance Evaluation of Concrete Using Electric Arc Furnace Oxidizing Slag Aggregate (전기로 산화슬래그 골재를 사용한 콘크리트의 성능 평가에 관한 연구)

  • Lim, Hee-Seob;Lee, Han-Seung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.4
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    • pp.97-103
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    • 2017
  • As the shortage of concrete aggregates is intensifying, the development of alternative resources is urgent. As the amount of steel slag increases year by year, attempts are being made to recycle slag into high-value-added products in order to develop an efficient resource recycling industry based on slag and to obtain economic benefits. However, the use of electric arc furnace oxidizing slag (EOS) as building materials is practically limited because it contains unstable materials. In this paper, physical properties of concrete were evaluated by using electric arc furnace slag aggregate. It has been produced with two levels of general strength area W / C 45% and high strength area W / C 30%. Fresh concrete has been tested in air content, flow and slump, unit weight. The properties of the cured concrete were investigated by compressive strength, bending strength and unit volume weight. As a result of this study, strength of concrete increased with increasing EOS aggregate mixture.

Evaluation of Corrosion Resistance with Grout Type and Tendon (그라우트 품질을 고려한 텐던의 부식저항성 평가)

  • Ryu, Hwa-Sung;An, Ki-Hong;Koh, Kyung-Taek;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.76-82
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    • 2018
  • Grout in duct is very effective protection from tendon corrosion in PSC(Prestressed Concrete) structure. In the work, durability and mechanical tests are performed for two types of grout which are conventionally used one and the improved grout with reduced w/c (water to cement) ratio and silica fume. Tendon system with 1000mm height is prepared and various tests including strength, flow, absorption, and bleeding ratio are conducted. ICM(Impressed Current Method) is adopted for corrosion acceleration in tendon with 12.7mm diameter inside grout. For 2 and 4 days, corrosion acceleration is performed for 2 different type of grout and corrosion amount is investigated. The improved grout shows higher compressive strength by 10 MPa and lower absorption ratio by 50% than the conventional one. It also provides an excellent corrosion reduction to 39.8 %~48.2 % for 2~4 days of acceleration period.

Numerical Studies on the Control Performance of Fiber Orientation for Nozzle with Inside Blades (타설 노즐의 내부 블레이드에 의한 섬유 방향성 제어 성능에 관한 수치 해석적 연구)

  • Lee, Jong-Han
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.6
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    • pp.157-163
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    • 2018
  • This study is aimed at controlling the fiber orientation and improve the fiber distribution in fiber-reinforced cement composites using blades that can be placed inside the existing nozzles. To optimize the blade parameters, multi-physics finite element analysis was performed that could account for the flow of the cementitious matrix material, the movement of the entrained fibers, and the interactions with the nozzle. As a result, this study defined the blade distance, length, and position as a function of the fiber length to be used in the field. The blades with a distance from 1.2 to 2.4 times the fiber length and length from 4 to 8 times the fiber length, as well as located at below 14 times the fzfiber length from the nozzle exit maintained the fiber orientation angle less than $5^{\circ}$. In addition, the blade-type nozzle proposed in the study can be attachable and detachable to the conventional casting equipment, and thus it can provide the usability and convenience in practical applications.