• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2000-2010
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• 2021

Mechanical moduli, such as Young's modulus (E), Bulks modulus (B), Shear modulus (S), longitudinal modulus (L), Poisson's ratio (σ) and micro Hardness (H) were theoretically calculated for (100-x)TeO₂+x MgO glasses, where x = 10, 20, 30, 40 and 45 mol%, based on the Makishima-Mackenzie model. The estimated results showed that the mechanical moduli and the microhardness of the glasses were improved with the increase of the MgO contents in the TM glasses, while Poisson's ratio decreased with the increase in MgO content. Moreover, the radiation shielding capacity was evaluated for the studied TM glasses. Thus, the linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), transmission factor (TF) and half-value thickness (𝚫_0.5) were simulated for gamma photon energies between 0.344 and 1.406 MeV. The simulated results showed that glass TM10 with 10 mol % MgO possess the highest LAC and varied in the range between 0.259 and 0.711 cm^-1, while TM45 glass with 45 mol % MgO possess the lowest LAC and vary in the range between 0.223 and 0.587 cm^-1 at gamma photon energies between 0.344 and 1.406 MeV. Furthermore, the BXCOM program was applied to calculate the effective atomic number (Z_eff), equivalent atomic number (Z_eq) and buildup factors (EBF and EABF) of the glasses. The effective removal cross-section for the fast neutrons (ERCSFN, ∑_R) was also calculated theoretically. The received data depicts that the lowest ∑_R was achieved for TM10 glasses, where ∑_R = 0.0193 cm² g^-1, while TM45 possesses the highest ERCSFN where ∑_R = 0.0215 cm² g^-1.

• Journal of Preventive Medicine and Public Health
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• v.55 no.6
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• pp.578-585
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• 2022

Objectives: This study aimed to adapt the survey questionnaire designed by Moens et al. (2021) and determine the validity and reliability of the Arabic version of the survey in a sample of the Saudi population experiencing teleworking. Methods: The questionnaire includes 2 sections. The first consists of 13 items measuring the impact of extended telework during the coronavirus disease 2019 (COVID-19) crisis. The second section includes 6 items measuring the impact of the COVID-19 crisis on selfview of telework and digital meetings. The survey instrument was translated based on the guidelines for the cultural adaptation of self-administrated measures. Results: The reliability of the questionnaire responses was measured by Cronbach's alpha. The construct validity was checked through exploratory factor analysis followed by confirmatory factor analysis (CFA) to further assess the factor structure. CFA revealed that the model had excellent fit (root mean square error of approximation, 0.00; comparative fit index, 1.0; Tucker-Lewis index, 1; standardized root mean squared residual, 0.0). Conclusions: The Arabic version of the teleworking questionnaire had high reliability and good validity in assessing experiences and perceptions toward teleworking. While the validated survey examined perceptions and experiences during COVID-19, its use can be extended to capture experiences and perceptions during different crises.

• Transactions of Materials Processing
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• v.32 no.6
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• pp.311-320
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• 2023

Recently, lightweight of automotive parts has been required to solve environmental problems caused by global warming. Accordingly, research and development are proceeded on manufacturing of parts using aluminum that can replace steel for lightweight of the automotive parts. In addition, high strength aluminum can be applied to body parts in order to meet both requirements of lightening and improving crash safety of vehicle. In this study, hot blow forming of roof side rail is employed to manufacturing of the automotive parts with high strength aluminum tube. In hot blow forming, longer forming times and excessive thinning can be occurred as compared with conventional manufacturing processes. So optimization of process conditions is required to prevent excessive thinning and to uniformize thickness distribution with fast forming time. Mechanical properties of high strength aluminum are obtained from tensile test at high temperature. These properties are used for finite element(FE) analysis to investigate the effect of strain rate on thinning and thickness distribution. Variation of thickness was firstly investigated from the result of FE analysis according to tube diameter, where the shapes at cross section of roof side rail are compared with allowable dimensional tolerance. Effective tube diameter is determined when fracture and wrinkle are not occurred during hot blow forming. Also FE analysis with various pressure-time profiles is performed to investigate the their effects on thinning and thickness distribution which is quantitatively verified with thinning factor. As a results, optimal process conditions can be determined for the manufacturing of roof side rail using high strength aluminum.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3501-3511
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• 2024

Titanium alloys play a vital role in optimizing the effectiveness and security of nuclear reactors, strengthening structural durability, and facilitating the effective handling of nuclear waste. The aim of this study is to investigate the gamma-ray, neutron, and transmission properties of four common titanium alloys through the examination of the deposited energy amount in the liquid sodium coolant material, in relation to the mechanical properties of these alloys. MCNP (version 6.3) is utilized for designing the titanium pipes. Next, the pipes were re-designed considering the elemental mass fractions and densities of the investigated titanium alloys. Grade 26 sample is reported with the highest values of mass attenuation coefficients and the lowest HVL values among those investigated alloys. Grade 26 is reported to have the lowest TF value, whereas Grade 12 demonstrated the highest TF value. The highest Effective Removal Cross Section (Σ_R, 1/cm) value against fast neutrons is reported for Grade 26. The utilization of Grade 26 sample as pipe material resulted in the lowest deposited energy amount (MeV/g) and subsequent lowest contamination in the coolant material. Out of the alloys that were chosen for analysis, it has been determined that Grade 26 exhibits the highest level of strength. It can be concluded that the Grade 26 alloy exhibits desirable characteristics for applications in nuclear technologies that require superior gamma-ray and neutron absorption properties, as well as exceptional mechanical properties. Nevertheless, it is essential to emphasize the importance for ongoing studies to enhance the existing material properties of Grade 26, with the aim of achieving improved safety and efficacy in nuclear applications.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3335-3346
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• 2024

Due to the radiation released by commonly used isotopes, many nuclear, medical, and industrial facilities require proper radiation shielding. In this work, distinct copper borate glasses intercalated with varied aluminum and vanadium oxide (Al₂O₃ and V₂O₅) content have been synthesized and used against radiation (gamma rays and fast/thermal neutrons). The different percents were as follows: [60% B₂O₃ + 35% CuO + (5-x)% Al₂O₃ + xV₂O₅], where x = 0, 1, and 2.5 wt.%, which was coded as BCu(5-x)Al:xV. The synthesized glass samples were characterized using Fourier transforms, infrared, and X-Raydiffraction analysis. Experimentally, the radiation shielding possessions of the samples were established using an HPGe detector at the gamma energy lines 0.356 MeV, 0.661 MeV, 1.173 MeV, and 1.332 MeV. Also, the prepared glasses were investigated theoretically using the Monte Carlo code (MCNP5) at photon energies of 0.015-15 MeV. Also, the fast and thermal neutron macroscopic effective removal cross-sections were calculated using MRCsC and JANIS-4.1 software, respectively. The prepared sample BCu2.5Al:2.5V, which has a vanadium and aluminum content of 2.5%, has the highest linear attenuation coefficient as well as the highest removal cross-section for fast, and thermal neutrons.

• Tuberculosis and Respiratory Diseases
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• v.57 no.4
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• pp.345-350
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• 2004

Background : To evaluate the frequency and clinical significance of lymph node micrometastasis in patients of non-small-cell lung cancer pathologically staged to be T1-2,N0. Method : From consecutive 29 patients of non-small-cell lung cancer who received curative operation and routine systemic nodal dissection, we immunohistochemically examined 806 lymph nodes from mediastinal, hilar and peribronchial lesion. All slides were stained with hematoxylin and eosin staining for one section and with cytokeratin AE1/AE3 antibody for another consecutive section of same lymph node to find out micrometastasis. Results : In 806 lymph nodes examined, no tumor cell was seen on hematoxylin and eosin staining and micrometastic foci were shown to be on 0.37%(3) of 806 lymph nodes, in which were upper paratracheal, interlobar and peribronchial lymph node. These three positive stains constitute 10.3%(3) of the 29 patients with non-small-cell lung cancer. Nine patients died from disease progression(4), postoperative complication(3) and concomitant diseases(2). The four patients with disease progression did not show evidence of micrometastasis on their lymph node examination. Conclusion : The frequency of lymph node micrometastasis was in 0.37% of 806 lymph nodes examined. The study results might suggested that routine analysis of micrometastasis on the lymph node didn't give any clinical implication on patients with non-small-cell lung cancer.

• Journal of Korean Society of Steel Construction
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• v.27 no.6
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• pp.513-523
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• 2015

In steel moment frames constructed of H-shapes, strong-axis moment connections should be used for maximum structural efficiency if possible. And most of cyclic seismic testing, domestic and international, has been conducted for strong-axis moment connections and cyclic test data for weak-axis connections is quite limited. However, when perpendicular moment frames meet, weak-axis moment connections are also needed at the intersecting locations. Especially, both strong- and weak-axis moment connections have been frequently used in domestic practice. In this study, cyclic seismic performance of RBS (reduced beam section) weak-axis welded moment connections was experimentally investigated. Test specimens, designed according to the procedure proposed by Gilton and Uang (2002), performed well and developed an excellent plastic rotation capacity of 0.03 rad or higher, although a simplified sizing procedure for attaching the beam web to the shear plate in the form of C-shaped fillet weld was used. The test results of this study showed that the sharp corner of C-shaped fillet weld tends to be the origin of crack propagation due to stress concentration there and needs to be trimmed for the better weld shape. Different from strong-axis moment connections, due to the presence of weld access hole, a kind of CJP butt joint is formed between the beam flange and the horizontal continuity plate in weak-axis moment connections. When weld access hole is large, this butt joint can experience cyclic local buckling and subsequent low cycle fatigue fracture as observed in this testing program. Thus the size of web access hole at the butt joint should be minimized if possible. The recommended seismic detailing such as stickout, trimming, and thicker continuity plate for construction tolerance should be followed for design and fabrication of weak-axis welded moment connections.

• Journal of Korean Society of Steel Construction
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• v.25 no.2
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• pp.115-130
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• 2013

In this study, lateral-torsional buckling (LTB) strength of high-strength H-beams built up from 800MPa tensile-strength steel was experimentally and analytically evaluated according to current lateral stability provisions (KBC 2009, AISC-LRFD 2010). The motivation was to evaluate whether or not current LTB provisions, which were originally developed for ordinary steel with different stress-strain characteristics, are still applicable to high-strength steel. Two sets of compact-section specimens with relatively low (Set A) or high (Set B) warping stiffness were prepared and tested under uniform moment loading. Laterally unbraced lengths of the test specimens were controlled such that inelastic LTB could be induced. All specimens exhibited LTB strength exceeding the minimum limit required by current provisions by a sufficient margin. Moreover, some specimen in Set A reached a rotation capacity required for plastic design, although its laterally unbraced length belonged to the inelastic LTB range. All the test results indicated that extrapolation of current provisions to high-strength steel is conservative. In order to further analyze the test results, the relationship between inelastic moment and laterally unbraced length was also derived in explicit form for both ordinary- and high-strength steel based on the effective tangent modulus of inelastic section. The analytical relationship derived again showed that extrapolation of current laterally unbraced length limit leads to a conservative design in the case of high-strength steel and that the laterally unbraced length to control the inelastic LTB behavior of high-strength steel beam should be specified by including its unique post-yield strain-hardening characteristics.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.25-32
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• 2009

Currently, various types of TDM (Transportation Demand Management) policies are being studied and implemented in an attempt to overcome the limitations of supply oriented policies. In this context, this paper addressed issues of effectiveness and possible domestic implementation of the HOT lane. The possible site of implementation selected for this simulation study is part of the Kyung-bu freeway, where a dedicated bus lane is currently being operated. Minimum length of distance required in between interchanges and access points of the HOT lane for vehicles to safely enter and exit the lane, and traffic management policies for effectively managing the weaving traffic trying to enter and exit the HOT lane were presented. A 5.2km section of freeway from Ki-heuing IC to Suwon IC and a 8.3km section from Hak-uei JC to Pan-gyo JC have been selected as possible sites of implementation for the HOT lane, in which congestion occurs regularly due to the high level of travel demand. VISSIM simulation program has been used to analyze the effects of the HOT lane under the assumption that one-lane HOT lane has been put into operation in these sections and that the lane change rate were in between 5% to 30%. The results of each possible scenario have proven that overall travel speed on the general lanes have increased as well by 1.57~2.62km/h after the implementation of the HOT lane. It is meaningful that this study could serve as a basic reference data for possible follow-up studies on the HOT lane as one effective method of TDM policies. Considering that the bus travel rate would continue increase and assuming the improvement in travel speed on general lanes, similar case study can be implemented where gaps between buses on bus lane are available, as a possible alternative of efficient bus lane management policies.

• Journal of Korean Society of Transportation
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• v.30 no.1
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• pp.59-72
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• 2012

In aspects of traffic operation, a climbing lane may cause traffic congestion if the volume of traffic (v/c) grows and the ratio of heavy vehicle increases. Conversely, it would be effective, if the climbing lane is dynamically operated according to changes in traffic flow. However, there are no guideline to effectively control this climbing lane in aspects of traffic operation. In this study, we examine the necessity of flexible traffic operation criteria and its process for dynamic traffic management and also establish and analyze the effect of flexible traffic operation criteria in accordance with traffic properties using an example of climbing lane. We selected the operation criteria (critical travel speed), which decides whether to operate or close the climbing lane when the average travel speed of climbing lane is 50km/h based on VISSM (microscopic traffic simulation) analysis of Nakdong junction towards Masan with the volume of traffic (v/c), ratio of heavy vehicle as the traffic operation parameters. Based on the simulation result in accordance with the volume of traffic by the operation mode of climbing lane, the analysis on the effect of dynamic traffic management of climbing lane showed that the dynamic traffic management provides more convenience compare to the operation and close of climbing lane. Thereby, we proved that the dynamic traffic management of climbing lane is more effective.