• Title/Summary/Keyword: longitudinal studies

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Ultra Low Field Sensor Using GMI Effect in NiFe/Cu Wires

  • Kollu, Pratap;Kim, Doung-Young;Kim, Cheol-Gi
    • Journal of Magnetics
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    • v.12 no.1
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    • pp.35-39
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    • 2007
  • A highly sensitive magnetic sensor using the Giant MagnetoImpedance effect has been developed. The sensor performance is studied and estimated. The sensor circuitry consists of a square wave generator (driving source), a sensing element in a form of composite wire of a 25 $\mu$m copper core electrodeposited with a thin layer of soft magnetic material ($Ni_{80}Fe_{20}$), and two amplifier stages for improving the gain, switching mechanism, scaler circuit, an AC power source driving the permeability of the magnetic coating layer of the sensing element into a dynamic state, and a signal pickup LC circuit formed by a pickup coil and an capacitor. Experimental studies on sensor have been carried out to investigate the key parameters in relation to the sensor sensitivity and resolution. The results showed that for high sensitivity and resolution, the frequency and magnitude of the ac driving current through the sensing element each has an optimum value, the resonance frequency of the signal pickup LC circuit should be equal to or twice as the driving frequency on the sensing element, and the anisotropy of the magnetic coating layer of the sensing wire element should be longitudinal.

Market Structure, Conduct, and Performance of the Creative Industry in Indonesia

  • DJULIUS, Horas;XIAO, Lixian;JUANIM, Juanim;PRIATNA, Deden Komar;MUNAWAROH, Siti
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.12
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    • pp.337-343
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    • 2021
  • The study's objective is to ascertain the state of the creative industry's market structure, the behavior of entrepreneurs ("conduct"), and the performance of the creative industry in Indonesia. Additionally, this study evaluates the relationship between structure, conduct, and performance within the context of the relationship between the three. This study analyzes longitudinal data from 2005 to 2015 for sub-sectors within the creative industry. The first step is to group statistical sub-sectors into creative-industry categories. The next step is to quantify and analyze the structure, behavior, and performance indicators of each creative industry subsector. Then, using a random effect panel data model, the relationship between structure and performance was estimated and examined. The findings of this study suggest that market share and concentration ratio calculations indicate that the creative industry in Indonesia has a monopolistic market structure. With this market framework, the creative industry's conduct can have an effect on prices. This is undoubtedly consistent with the features of the creative industry, which emphasize innovation as a means of adding value. The panel data estimation findings suggest the need for long-term efforts to maintain a market framework that enables businesses to compete fairly, innovate, and bring value.

Case studies on the probabilistic characteristics of ultimate strength of stiffened panels with uniform and non-uniform localized corrosion subjected to uniaxial and biaxial thrust

  • Cui, Jinju;Wang, Deyu;Ma, Ning
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.11 no.1
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    • pp.97-118
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    • 2019
  • Based on Nonlinear Finite Element Analysis (NFEA), this paper focuses on the bi-axial ultimate strength of typical bottom structures under corrosion. On one hand, uniform and not simultaneous corrosion across different structures is introduced, and surrogate models by Gaussian Process (GP) are built for both longitudinal and transverse cases individually, and corresponding probabilistic characteristics are investigated; meanwhile, corrosion effects on interaction between bi-axial stresses at ultimate state are studied. On the other hand, non-uniform localized pitting corrosion of normally distributed circular shapes is introduced, and different pitting corrosion densities are considered; structural bi-axial ultimate strengths under pitting corrosion are studied, and the results are compared with that from equivalent uniform corrosion; the probabilistic characteristics of structural ultimate strength in life cycle are studied; finally, the ultimate strength under randomly distributed pitting corrosion is compared with results from normally distributed pitting and uniform corrosion under various boundary conditions.

Local buckling of reinforcing steel bars in RC members under compression forces

  • Minafo, Giovanni
    • Computers and Concrete
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    • v.22 no.6
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    • pp.527-538
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    • 2018
  • Buckling of longitudinal bars is a brittle failure mechanism, often recorded in reinforced concrete (RC) structures after an earthquake. Studies in the literature highlights that it often occurs when steel is in the post elastic range, by inducing a modification of the engineered stress-strain law of steel in compression. A proper evaluation of this effect is of fundamental importance for correctly evaluating capacity and ductility of structures. Significant errors can be obtained in terms of ultimate bending moment and curvature ductility of an RC section if these effects are not accounted, as well as incorrect evaluations are achieved by non-linear static analyses. This paper presents a numerical investigation aiming to evaluate the engineered stress-strain law of reinforcing steel in compression, including second order effects. Non-linear FE analyses are performed under the assumption of local buckling. A role of key parameters is evaluated, making difference between steel with strain hardening or with perfectly plastic behaviour. Comparisons with experimental data available in the literature confirm the accuracy of the achieved results and make it possible to formulate recommendations for design purposes. Finally, comparisons are made with analytical formulations available in the literature and based on obtained results, a modification of the stress-strain law model of Dhakal and Maekawa (2002) is proposed for fitting the numerical predictions.

Cognitive dysfunctions in individuals with diabetes mellitus

  • Kim, Hye-Geum
    • Journal of Yeungnam Medical Science
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    • v.36 no.3
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    • pp.183-191
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    • 2019
  • Some patients with type 1 and type 2 diabetes mellitus (DM) present with cognitive dysfunctions. The pathophysiology underlying this complication is not well understood. Type 1 DM has been associated with a decrease in the speed of information processing, psychomotor efficiency, attention, mental flexibility, and visual perception. Longitudinal epidemiological studies of type 1 DM have indicated that chronic hyperglycemia and microvascular disease, rather than repeated severe hypoglycemia, are associated with the pathogenesis of DM-related cognitive dysfunction. However, severe hypoglycemic episodes may contribute to cognitive dysfunction in high-risk patients with DM. Type 2 DM has been associated with memory deficits, decreased psychomotor speed, and reduced frontal lobe/executive function. In type 2 DM, chronic hyperglycemia, long duration of DM, presence of vascular risk factors (e.g., hypertension and obesity), and microvascular and macrovascular complications are associated with the increased risk of developing cognitive dysfunction. The pathophysiology of cognitive dysfunction in individuals with DM include the following: (1) role of hyperglycemia, (2) role of vascular disease, (3) role of hypoglycemia, and (4) role of insulin resistance and amyloid. Recently, some investigators have proposed that type 3 DM is correlated to sporadic Alzheimer's disease. The molecular and biochemical consequences of insulin and insulin-like growth factor resistance in the brain compromise neuronal survival, energy production, gene expression, plasticity, and white matter integrity. If patients claim that their performance is worsening or if they ask about the effects of DM on functioning, screening and assessment are recommended.

Behavioral trends of shear strengthened reinforced concrete beams with externally bonded fiber-reinforced polymer

  • Barakat, Samer;Al-Toubat, Salah;Leblouba, Moussa;Burai, Eman Al
    • Structural Engineering and Mechanics
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    • v.69 no.5
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    • pp.579-589
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    • 2019
  • Numerous experimental studies have been conducted on reinforced concrete (RC) beams strengthened in shear with externally bonded fiber reinforced polymer (EBFRP). The objectives of this work are to study the behavioral trends of shear strengthened EBFRP RC beams after updating the existing database. The previously published databases have been updated, enriched and cross checked for completeness, redundancy and consistency. The updated database now contains data on 698 EBFRP beams and covers the time span from 1992 to 2018. The collected database then refined applying certain filters and used to investigate and capture better interactions among various influencing parameters affecting the shear strength of EBFRP beams. These parameters include the type and properties of FRP, fiber orientation as well as the strengthening scheme, the shear and the longitudinal steel reinforcement ratios, the shear span ratio, and the geometry of the member. The refined database is used to test the prediction accuracy of the existing design models. Considerable scatters are found in the results of all tested prediction models and in many occasions the predictions are unsafe. To better understand the shear behavior of the EBFRP RC beams and then enhance the prediction models, it was concluded that focused experimental programs should be carried out.

A Study on the Job Career Patterns of Korean IT Personnel

  • Lee, Kyoungnam
    • Journal of Information Technology Services
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    • v.17 no.4
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    • pp.37-52
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    • 2018
  • With the increasing severity of the shortage of highly-skilled IT personnel, more and more attention is being paid to the professional career path and systematic career management of IT employees. Although some studies have been conducted to describe the current status of IT personnel, limited attempts have been made to analyze the career paths or career patterns of IT professionals from a longitudinal perspective. In this context, this study explored the job career patterns of IT professionals in Korea and examined their relationship with subjective and objective career success. To identify job career patterns over time, detailed information about jobs and positions were used and an optimal matching analysis (OMA) was conducted to calculate the dissimilarity matrix between employees' career sequences, while a cluster analysis was used to categorize the meaningful groups based on this dissimilarity data. This analysis revealed that career patterns among Korean IT personnel are more varied than previously thought. These career types have a significant relationship with individual profiles, such as age, education, industry and company size, and account for significant variations in the three main career success variables, i.e. quality of life, assessment of software quality, and wage level. It is expected that the findings of this study will contribute to refining the Korean career path so as to retain IT personnel, and raise the need to improve the low quality of life and poor SW work environment of IT personnel.

Determining the shear strength of FRP-RC beams using soft computing and code methods

  • Yavuz, Gunnur
    • Computers and Concrete
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    • v.23 no.1
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    • pp.49-60
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    • 2019
  • In recent years, multiple experimental studies have been performed on using fiber reinforced polymer (FRP) bars in reinforced concrete (RC) structural members. FRP bars provide a new type of reinforcement that avoids the corrosion of traditional steel reinforcement. In this study, predicting the shear strength of RC beams with FRP longitudinal bars using artificial neural networks (ANNs) is investigated as a different approach from the current specific codes. An ANN model was developed using the experimental data of 104 FRP-RC specimens from an existing database in the literature. Seven different input parameters affecting the shear strength of FRP bar reinforced RC beams were selected to create the ANN structure. The most convenient ANN algorithm was determined as traingdx. The results from current codes (ACI440.1R-15 and JSCE) and existing literature in predicting the shear strength of FRP-RC beams were investigated using the identical test data. The study shows that the ANN model produces acceptable predictions for the ultimate shear strength of FRP-RC beams (maximum $R^2{\approx}0.97$). Additionally, the ANN model provides more accurate predictions for the shear capacity than the other computed methods in the ACI440.1R-15, JSCE codes and existing literature for considering different performance parameters.

Investigation on Ultimate Strength of STS304L Stainless Steel Welded Connection with Base Metal Fracture Using Finite Element Analysis

  • Lee, HooChang;Kim, TaeSoo;Hwang, BoKyung;Cho, TaeJun
    • International journal of steel structures
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    • v.18 no.4
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    • pp.1139-1152
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    • 2018
  • Many studies on the application of stainless steels as structural materials in buildings and infra-structures have been performed thanks to superior characteristics of corrosion resistance, fire resistance and aesthetic appeal. Experimental investigation to estimate the ultimate strength and fracture mode of the fillet-welded connections of cold-formed austenitic stainless steel (STS304L) with better intergranular corrosion resistance than that of austenitic stainless steel, STS304 commonly used has carried out by authors. Specimens were fabricated to fail by base metal fracture not weld metal fracture with main variables of weld lengths according to loading direction. All specimens showed a block shear fracture mode. In this paper, finite element analysis model was developed to predict the ultimate behaviors of welded connection and its validity was verified through the comparison with test results. Since the block shear behavior of welded connection due to stress triaxiality and shear-lag effects is different from that of bolted connection, stress and strain distributions in the critical path of tensile and shear fracture section were investigated. Test and analysis strengths were compared with those by current design specifications such as AISC, EC3 and existing researcher's proposed equations. In addition, through parametric analysis with extended variables, the conditions of end distance and longitudinal weld length for block shear fracture and tensile fracture were suggested.

High and Downwardly Rigid Reservation Wages are Responsible for the Youth Joblessness? (청년 고용 문제, 눈높이 때문인가?)

  • Lee, Byung-Hee
    • Korean Journal of Labor Studies
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    • v.17 no.1
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    • pp.71-94
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    • 2011
  • This paper criticizes the arguments for the high and rigid reservation wages as main cause of the youth joblessness. First, using longitudinal aspect of the Korea Labor and Income Panel Study, I found that there exists declining reservation wage for the young who make the transition from unemployed to employment. Second, the average duration of school-to-work transition in Korea is relatively low compared to that of other countries. Moreover the duration between leaving school and staring the first job has not significantly negative effect on adult labor market outcomes, but the quality of first job and unstable job experiences have serious negative effects on working career. These findings show that the high youth joblessness is due to both decent job deficit and labor market segmentation.