• Title/Summary/Keyword: STS Content

Search Result 85, Processing Time 0.02 seconds

Study of High Temperature Corrosion Behavior of Fe-Cr Steel in Sewage Sludge-(SO2-O2-H2O-bal. CO2) mixed Gas Environment (하수슬러지-(SO2-O2-H2O-bal. CO2) 혼합 가스 분위기에서 Fe-Cr 강의 고온부식거동 연구)

  • Kim, Min Jung;Park, Joo Chang;Ryu, In Sun
    • Journal of the Korean institute of surface engineering
    • /
    • v.53 no.2
    • /
    • pp.72-79
    • /
    • 2020
  • Two Fe-Cr steels of T22 steel and STS430 steel were corroded at 650 and 750℃ for 100hr in sewage sludge-(0.3% SO2-6% O2-10% H2O-balance CO2) mixed gas environment. T22 steel corroded faster than STS430, indicating that the Cr content significantly influence the corrosion rates. T22 formed thick and non-protective Fe2O3 as the major oxide and Fe3O4 as the minor one. With an increase in corrosion temperature, their corrosion rates increased, being accompanied with formation of pores and cracks in the thickened oxide scales that were non-adherent. STS430 steel formed Fe2O3, Fe3O4 as the outer scale and (Fe, Cr)-O as the inner layer by which its corrosion rate is greatly reduced. Both the T22 and STS430 steel samples formed multi-layered scales by outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions at high-temperature more than 650℃.

Ensembles of neural network with stochastic optimization algorithms in predicting concrete tensile strength

  • Hu, Juan;Dong, Fenghui;Qiu, Yiqi;Xi, Lei;Majdi, Ali;Ali, H. Elhosiny
    • Steel and Composite Structures
    • /
    • v.45 no.2
    • /
    • pp.205-218
    • /
    • 2022
  • Proper calculation of splitting tensile strength (STS) of concrete has been a crucial task, due to the wide use of concrete in the construction sector. Following many recent studies that have proposed various predictive models for this aim, this study suggests and tests the functionality of three hybrid models in predicting the STS from the characteristics of the mixture components including cement compressive strength, cement tensile strength, curing age, the maximum size of the crushed stone, stone powder content, sand fine modulus, water to binder ratio, and the ratio of sand. A multi-layer perceptron (MLP) neural network incorporates invasive weed optimization (IWO), cuttlefish optimization algorithm (CFOA), and electrostatic discharge algorithm (ESDA) which are among the newest optimization techniques. A dataset from the earlier literature is used for exploring and extrapolating the STS behavior. The results acquired from several accuracy criteria demonstrated a nice learning capability for all three hybrid models viz. IWO-MLP, CFOA-MLP, and ESDA-MLP. Also in the prediction phase, the prediction products were in a promising agreement (above 88%) with experimental results. However, a comparative look revealed the ESDA-MLP as the most accurate predictor. Considering mean absolute percentage error (MAPE) index, the error of ESDA-MLP was 9.05%, while the corresponding value for IWO-MLP and CFOA-MLP was 9.17 and 13.97%, respectively. Since the combination of MLP and ESDA can be an effective tool for optimizing the concrete mixture toward a desirable STS, the last part of this study is dedicated to extracting a predictive formula from this model.

Review on the reliability of low frequency responses of locally operating sensors (국내 지진센서의 저주파 응답의 신뢰성에 관한 고찰)

  • 박동희;연관희;장천중
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • 2002.09a
    • /
    • pp.35-42
    • /
    • 2002
  • Frequency responses for most of the local seismic sensors in Korea have been roughly checked by mutual comparison of Fourier spectra of seismic records from accelerometer and seismometer, both of which are installed at the same location. Especially, because the frequency content of the seismic energy is usually above 1 Hz for local earthquakes, the reliability of low frequency response could have not been evaluated. Fortunately a recent large earthquake, Ms=7.2 on 02/06/29 containing dominant low frequency energy makes it possible to check the low frequency response of the seismic sensors, especially EpiSensor and JC-V100. Considering two types of sensor pairs, (STS-2 and EpiSensor, JC-V100 and EpiSensor), the low frequency response of EpiSensor is confirmed first by comparison with STS-2 which has proved low frequency response. Second, reliable low frequency limit of instrumentally corrected seismic data from JC-V100 data is estimated to be about 0.03 Hz by comparison with EpiSensor data.

  • PDF

Electroless Copper Plating on 304L Stainless Steel Powders and Corrosion Resistance of the Sintered Compacts of Composite Powders (304L 스테인리스강 분말의 내식성 개선을 위한 무전해 구리 도금과 분말 소결체의 내식성 조사 연구)

  • Ahn, Jae-Woo;Lee, Jae-Hoon
    • Korean Journal of Metals and Materials
    • /
    • v.47 no.2
    • /
    • pp.79-90
    • /
    • 2009
  • A study has been made about the effects of powder content, reaction temperature, reaction time, and stirring speed on the preparation of the stainless steel(STS) 304L powders plating with copper by an electroless plating method. The behavior of corrosion resistance of the sintered STS-Cu composite powders was also investigated by the salt spraying test The electroless plating technique was an effective method to manufactur the copper-uniform plating composite powders, the corrosion resistance of this sintered specimen was improved bysuppressing Cr precipitates on grain boundaries in the sintered compacts of composite powders.

Effect of Ammonium Thiosulfate on Biological Activity in a Paddy Soil (Ammonium Thisoulfate 처리가 담수(湛水) 답토양(畓土壤)의 생물활성(生物活性)에 미치는 영향)

  • Lim, Sun-Uk;Seo, Young-Ho
    • Korean Journal of Soil Science and Fertilizer
    • /
    • v.27 no.1
    • /
    • pp.40-47
    • /
    • 1994
  • The objective of this research was to examine the effect of ammonium thiosulfate(ATS) on urease activity and on biological and chemical properties of flooded paddy soil especially having high organic matter content by comparing with the effect of sodium thiosulfate(STS). The results obtained are summarized as follows. 1. The hydrolysis of urea was inhibited at 3 and 5 days after treatment of thiosulfate(ATS and STS) +glucose and thiosulfate only, respectively. The inhibitory effect of ATS on urea hydrolysis was slightly lower than that of STS in glusoce-added soils, but when the glucose was not added, the effects of ATS and STS were not different significantly. 2. The soil pH and Eh was lowered by 0.3~0.5 units and 30~120 mV, respectively, when incubated flooded soil with ATS and glucose at $25^{\circ}C$. 3. Soil respiration rate in/flooded soil was increased by 10~70% with the treatment of ATS during the 20 day experimental period. 4. The contents of acetic and butyric acid in thiosulfate treatment soil was below $10{\mu}g/g$, which was lower than that($220.3{\mu}g/g$) of critical growth inhibition of rice.

  • PDF

An Analysis of Inquiry Activities of the High School Common Science Textbook(Materials Part) By Using 3-Dimensional Analysis Framework (3차원 분석틀을 이용한 고등학교 공통과학(물질 부분) 교과서의 탐구 활동 분석)

  • Kim, Yun-Hi;Moon, Seong-Bae
    • Journal of The Korean Association For Science Education
    • /
    • v.20 no.2
    • /
    • pp.274-287
    • /
    • 2000
  • This study was performed the analysis of four kinds of common science textbooks based on the 6th curriculum. Particularly, inquiry activity part was analyzed by the three dimension framework which consists of inquiry content dimension, inquiry process dimension and inquiry context dimension. In the analysis of the inquiry content dimension of inquiry activities, the contents revised by 6th curriculum of common science textbook was accomplished through various inquiry activities. The number of inquiry activity in four textbooks was similar as about 16. The For the analysis of inquiry process dimension, 'interpreting data and formulating generalizations' category (39.1%) was most emphasized and the categories of 'observation and measuring'(30.8%), and 'building, testing and revising the theoretical model' (16.5 %), 'seeing a problem and seeking ways to solve it' (13.5%) follow in order. As for the analysis of the inquiry context dimension, the proportion of STS related contents in inquiry activities was only 18%. So, we propose that STS related contents would increase the proportion for the following textbook.

  • PDF

Effect of Uniconazole and Silver Thiosulfate Treatment on Reduction of Ozone Injury in Snap Bean Plants (Uniconazole과 Silver Thiosulfate 처리(處理)가 강남콩의 오존피해(被害) 경감(輕減)에 미치는 효과(效果))

  • Ku, Ja Hyeong;Won, Dong Chan;Cho, Jeong Hee;Shin, Dae Shik
    • Korean Journal of Agricultural Science
    • /
    • v.19 no.2
    • /
    • pp.161-169
    • /
    • 1992
  • Studies were conducted to examine the effects of single or combined treatment of uniconazole [(E)-1-(4-chlorophenyl)-4, 4-dimethyl 2(1, 2,-4-triazol-1-yl)-1-penten-3-ol)] and silver thiosulfate (STS) on reducing ozone injury to snap beans (Phaseolus vulgaris L. 'Strike'). Two weeks after seeding, plants were given a soil drench of uniconazole(XE-1019) solution at concentrations of 0.001, 0.005 and 0.025 mg/pot, and then two days prior to ozone fumigation, 0.3 and 0.6 mM STS containing 0.01% Tween-20 were also sprayed. Uniconazole was effective in providing protection against ozone injury through increase activities of free radical scavengers such as superoxide dismutase (SOD) and peroxidase (POD) as well as the increase of chlorophyll content and stomatal resistance resulted from plant growth retardation. The phytoprotective effects of STS seemed to be related to its properly of blocking the ethylene action and increasing activities of SOD and POD. Even at low concentrations, a combined treatment with uniconazole drench, STS spray significantly reduced ozone injury compared to single application.

  • PDF

Postharvest Physiology and Prolonging Vase Life of Cut Freesia (Freesia refracta) (절화 프리지아의 수확후 생리 및 수명연장)

  • Kwon, Hye Jin;Hwang, Moon Joo;Kim, Ki Sun
    • Horticultural Science & Technology
    • /
    • v.17 no.3
    • /
    • pp.361-364
    • /
    • 1999
  • This study was conducted to examine the effects of pulsing treatment and to develop techniques treated right after harvest by grower for extending vase life and improving flower quality in cut freesia. Thirty minutes dipping treatment of STS 2 mM followed by 20 hr pulsing in sucrose 10% + BA 10 ppm + 8-HQS 300 ppm solution showed the best results in vase life and flower quality of cut freesia when kept in vase water. This pretreatment extended vase life by 24.7% than control, and improved quality of cut freesia significantly in flower diameter, percent flowering (35.4%), fresh weight, water uptake, and carotenoid content, and depressed ethylene production and respiration rate.

  • PDF

Characteristics of Fatigue Crack Propagation and Changes in Strain Induced Martensite α' of STS 304 Stainless Steel (LNG 304 스테인레스강의 피로균열전파특성과 변형유발 마르텐사이트 함량의 변화)

  • Kim, Song-Hee;Pak, Hyung-Rae;Lee, Hyun-Seung
    • Journal of Industrial Technology
    • /
    • v.21 no.B
    • /
    • pp.341-348
    • /
    • 2001
  • The effect of initial ${\alpha}^{\prime}$ in STS 304 Stainless Steel on fatigue resistance, and fatigue crack propagation behavior was studied with using C-T specimens. Higher ${\Delta}K_{th}$ was observed in the specimens with the content of 0% initial ${\alpha}^{\prime}$ than in the contents of 2% and 33% initial ${\alpha}^{\prime}$. The difference of da/dN at the same level of ${\Delta}K$ was distinctive in low and intermediate level of ${\Delta}K$ however became less different as the level of ${\Delta}K$ increased. It is because the formation of strain induced martensite occurred readily in lower ${\alpha}^{\prime}$ at the vicinity of the fatigue crack tip, which causes compressive residual stresses resulting in the enhancement of crack closure. In general fatigue cracks propagated transgranular mode and many segments of ridges were observed on the fracture surfaces. At the higher contents of initial ${\alpha}^{\prime}$ appeared the smaller size of ridge segments. Slips in austenite were blocked more frequently by the martensite colonies formed in austenite.

  • PDF

LIBS Analysis on Magnetic Force of Dissimilar Material Using SMAW (이종재료의 피복아크 용접에서 자기력에 따른 LIBS 해석)

  • Lee, Chul Ku;Lee, Wooram
    • Journal of Welding and Joining
    • /
    • v.31 no.4
    • /
    • pp.54-61
    • /
    • 2013
  • This paper reports mild steel(SPHC) and stainless steel(STS304) sheets commonly used for railroad cars or commercial vehicles such as in the automobile and shipbuilding industries. The sheets are used in these applications, which are mainly fabricated using the shielded metal arc welding(SMAW) of dissimilar materials. It also reports an interesting application of Laser Induced Breakdown Spectroscopy(LIBS) in order to determine the elemental composition diffusion of SPHC and STS304. Arc blow produced by magnetic force during the electric arc welding prevents the formation from a sound weldment. In particular, the mechanical properties of the joint are influenced by not only by geometrical and mechanical factors but also the welding conditions for the arc welded joint. Therefore, the mechanical properties and performance are evaluated by performing a physicochemical component analysis. And they increase in accordance with content of elements and microstructure in mild steel. As results, appropriate range for magnetic fields could be achieved. Therefore, the effect of magnetic force in a butt weld of mild steel plates was investigated by comparing to the measured data.