• Structural Engineering and Mechanics
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• v.57 no.3
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• pp.507-528
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• 2016

Reduced beam section (RBS) moment resisting connections are among the most economical and practical rigid steel connections developed in the aftermath of the 1994 Northridge and the 1995 Kobe earthquakes. Although the performance of RBS connection has been widely studied, this connection has not been subject to in the skewed conditions. In this study, the seismic performance of dogbone connection was investigated at different angles. The Commercial ABAQUS software was used to simulate the samples. The numerical results are first compared with experimental results to verify the accuracy. Nonlinear static analysis with von Mises yield criterion materials and the finite elements method were used to analyze the behavior of the samples The selected Hardening Strain of materials at cyclic loading and monotonic loading were kinematics and isotropic respectively The results show that in addition to reverse twisting of columns, change in beam angle relative to the central axis of the column has little impact on hysteresis response of samples. Any increase in the angle, leads to increased non-elastic resistance. As for Weak panel zone, with increase of the angle between the beam and the column, the initial submission will take place at a later time and at a larger rotation angle in the panel zone and this represents reduced amount of perpendicular force exerted on the column flange. In balanced and strong panel zones, with increase in the angle between the beam and the central axis of the column, the reduced beam section (RBS), reaches the failure limit faster and at a lower rotation angle. In connection of skewed beam, balanced panel zone, due to its good performance in disposition of plasticity process away from connection points and high energy absorption, is the best choice for panel zone. The ratio of maximum moment developed on the column was found to be within 0.84 to 1 plastic anchor point, which shows prevention of brittle fracture in connections.

• Earthquakes and Structures
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• v.11 no.5
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• pp.741-777
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• 2016

A simplified approach of assessing torsionally balanced (TB) and torsionally unbalanced (TU) low-medium rise buildings of up to 30 m in height is presented in this paper for regions of low-to-moderate seismicity. The Generalised Force Method of Analysis for TB buildings which is illustrated in the early part of the paper involves calculation of the deflection profile of the building in a 2D analysis in order that a capacity diagram can be constructed to intercept with the acceleration-displacement response spectrum diagram representing seismic actions. This approach of calculation on the planar model of a building which involves applying lateral forces to the building (waiving away the need of a dynamic analysis and yet obtaining similar results) has been adapted for determining the deflection behaviour of a TU building in the later part of the paper. Another key original contribution to knowledge is taking into account the strong dependence of the torsional response behaviour of the building on the periodic properties of the applied excitations in relation to the natural periods of vibration of the building. Many of the trends presented are not reflected in provisions of major codes of practices for the seismic design of buildings. The deflection behaviour of the building in response to displacement controlled (DC) excitations is in stark contrast to behaviour in acceleration controlled (AC), or velocity controlled (VC), conditions, and is much easier to generalise. Although DC conditions are rare with buildings not exceeding 30 m in height displacement estimates based on such conditions can be taken as upper bound estimates in order that a conservative prediction of the displacement profile at the edge of a TU building can be obtained conveniently by the use of a constant amplification factor to scale results from planar analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.391.2-391.2
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• 2014

Solution-processible hybrid bipolar field effect transistors (HBFETs) with balanced hole and electron mobilities were fabricated using a combination of the organic p-type poly (3-hexylthiophene) (P3HT) layer and inorganic n-type ZnO material. The hole and electron mobilities were first optimized in single layer devices by using acetonitrile as a solvent additive to process the P3HT and annealing to process the ZnO layer. The highest hole mobility of the P3HT-only-devices with 5% acetonitrile was 0.15 cm2V-1s-1, while the largest electron mobility was observed in the ZnO-only-devices annealed at $200^{\circ}C$ and found to be $7.2{\times}10-2cm2V-1s-1$. The inorganic-organic HBFETs consisting of P3HT with 5% acetonitrile and ZnO layer annealed at $200^{\circ}C$ exhibited balanced hole and electron mobilities of $4.0{\times}10-2$ and $3.9{\times}10-2cm2V-1s-1$, respectively. The effect on surface morphology and crystallinity by adding acetonitrile and thermal annealing were investigated through X-ray diffraction and atomic force microscopy (AFM). Our findings indicate that techniques demonstrated herein are of great utility in improving the performance of inorganic-organic hybrid devices

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3731-3735
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• 2015

This study reports the relationship between rollingstock weight and acceleration performance for HEMU-430X, the first electric multiple unit developed in Korea. While maintaining the consumed power, the total train weight was deliberately varied by 2%, by adding and removing weights, and the it was shown that the lighter train was found to have higher acceleration performance and hence better suited for maximum speed tests below the speed of 413km/h. According to the power consumption analysis based on the velocity data collected per 0.1 second, the balanced speed, when the traction force and air resistance become equal, was determined to be 419km/h for HEMU-430X, which is in agreement with tested result. It is expected that the analyses in this study will be utilized for the speed tests in the future.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.1
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• pp.1-12
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• 2010

The purpose of this study was to compare the strain on the alveolar ridge in the centric, eccentric and protrusive position according to the occlusal scheme (bilateral balanced occlusion with 33 degree anatomical teeth, group B; monoplane occlusion with non-anatomical teeth, group M; lingualized occlusion with 33 degree anatomical teeth and non-anatomical teeth, group L; of complete dentures. Experimental dentures were set bilateral balanced occlusion, lingualized occlusion and monoplane occlusion. They are analysed through T-Scan II(Tekscan, Boston, U.S.A) and 1.5mm thick layer was removed from the denture-supporting surface of resin model and then replaced with silicone to simulate resilient edentulous ridge mucosa. A $4{\times}6$ linear strain gauge is attached to the $1^{st}$ premolar and $1^{st}$ molar area. The strain values are recorded according to the occlusal scheme in the centric, eccentric and protrusive position after uniformly applying 50 N and 150 N force through a Universal Testing Machine(instron$^{(R)}$ 5567, Bluehill 2.0 software ,U.S.A.) with the models mounted in the articulator. When performing centric and protrusive occlusion, the three groups of occlusal scheme were compared in the anterior region and in the posterior region. The strains of each group were also compared in the working side and in the non-working side during eccentric excursion. It was observed that the strain in the bilateral balanced occlusion showed a higher value than the lingualized occlusion and monoplane occlusion in every position except the non-working side. However, during the eccentric movement the strain value in the non-working side showed the lowest value in the bilaterally balanced occlusion. The strain change amount from the working side or centric occlusion to non-working side and also the strain variation rate within the non-working side showed the highest value in bilateral balanced occlusion.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.457-471
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• 2015

A domestic cutterhead with the diameter of 3.6 m was designed and manufactured in this study. Then, it was attached to an existing earth-pressure balanced shield TBM to excavate a cable tunnel with the length of 1,275 m. Especially, the procedures for TBM cutterhead design and its corresponding performance prediction were also summarized. From field data analyses of the refurbished shield TBM, its maximum advance rate was recorded as 14.4 m/day. Penetration depths of disc cutters were found to be approximately 4 mm/rev, which is equal to the maximum penetration depth designed for the strongest rock strength condition in the target tunnel. Every TBM operating thrust and cutter normal force during TBM driving was much smaller than their corresponding maximum capacities. When cutter acting forces recorded in the field were analyzed, their prediction errors by the CSM model were very high for weak rock conditions. In addition, rock strength showed very close relationships with cutter normal force and penetration depth.

• Tribology and Lubricants
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• v.36 no.2
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• pp.105-115
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• 2020

This paper presents a numerical study on the rotordynamic analysis of a dual-spool turbofan engine in the context of blade defect events. The blades of an axial-type aeroengine are typically well aligned during the compressor and turbine stages. However, they are sometimes exposed to damage, partially or entirely, for several operational reasons, such as cracks due to foreign objects, burns from the combustion gas, and corrosion due to oxygen in the air. Herein, we designed a dual-spool rotor using the commercial 3D modeling software CATIA to simulate blade defects in the turbofan engine. We utilized the rotordynamic parameters to create two finite element Euler-Bernoulli beam models connected by means of an inter-rotor bearing. We then applied the unbalanced forces induced by the mass eccentricities of the blades to the following selected scenarios: 1) fully balanced, 2) crack in the low-pressure compressor (LPC) and high pressure compressor (HPC), 3) burn on the high-pressure turbine (HPT) and low pressure compressor, 4) corrosion of the LPC, and 5) corrosion of the HPC. Additionally, we obtained the transient and steady-state responses of the overall rotor nodes using the Runge-Kutta numerical integration method, and employed model reduction techniques such as component mode synthesis to enhance the computational efficiency of the process. The simulation results indicate that the high-vibration status of the rotor commences beyond 10,000 rpm, which is identified as the first critical speed of the lower speed rotor. Moreover, we monitored the unbalanced stages near the inter-rotor bearing, which prominently influences the overall rotordynamic status, and the corrosion of the HPC to prevent further instability. The high-speed range operation (>13,000 rpm) coupled with HPC/HPT blade defects possibly presents a rotor-case contact problem that can lead to catastrophic failure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.337-342
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• 2010

Generally most sluice gates are closed and opened by a mechanical winch, a winch using an oil-pressure, or a winch mixing both. Because of their size and structure, they should be safely operated with more than two pulling devices helping each other. At the moment of their opening and closing, there usually occur some additional loads to the structure which cannot be exactly measurable at the stage of designing. Such additional loads can cause the sluice gate to be unbalanced and make it hard to open and close the gate, and by also overloading a winch, they can inflict a significant damage to the safety of the sluice gate. This paper explains a FDC(Force-Displacement Control) system which simultaneously considered the oil-pressure and displacement in order to evenly distribute the force and make a winch balanced at the opening and closing motion. This FDC system was implemented by means of the PID(Proportional Integral Derivative) function of XG 5000 program. It was experimented on a model of the sluice gate winch with the hydraulic oil pressure cylinder. The experiments showed that the developed FDC system made the winch of hydraulic oil pressure cylinder open and close cooperatively in spite of various external loads. Therefore the FDC system is proven effective when it is applied to a winch of sluice gate.

• Korean Journal of Child Studies
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• v.37 no.2
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• pp.169-187
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• 2016

Objective: This study aimed to identify profiles based on early childhood and elementary school teachers' goal orientations and to examine differences in teacher efficacy, psychological wellbeing, and job satisfaction among these profile groups. Methods: Data were collected through a teacher questionnaire. The teacher goal-orientation scale consisted of six sub-dimensions: growth, leisure, wealth, relationship, promotion, and social contribution. Data were analyzed using latent profile analyses. Results: Latent profile analyses revealed three distinct profile groups: one group characterized by higher scores across all six dimensions (balanced-goal-orientation group); another characterized by lower scores on all six dimensions, with a relatively higher score on the relationship dimension (relationship-goal-oriented group); another one characterized by lower scores on all dimensions except the leisure goal (leisure-goal-oriented group). MANOVA showed that the balanced-goalorientation group was significantly higher in total years of teaching, educational attainment, and age, compared to the leisure-goal-oriented group. In regression analyses, when controlling for educational attainment, teacher types (kindergarten vs. elementary school) did not significantly predict each of the dummy-coded profile groups (0 = no, 1 = yes). When taking into account teachers' age and educational attainment, belonging to the balanced-goal-orientation group was consistently associated with higher levels of teacher efficacy, job satisfaction, and psychological well-being, whereas the opposite pattern was observed in leisure-goal-oriented group. Conclusion: These findings imply that it is crucial to help pre- and in-service kindergarten and elementary school teachers foster a balance between different types of goals, which would ultimately strengthen and stabilize the supply of a teaching force and the provision of a better education.

• Journal of the Korean Society of Systems Engineering
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• v.11 no.2
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• pp.61-73
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• 2015

The early-phase naval ship design demands requirements synthesis rather than design synthesis, which conducts engineering design for several domains on a detailed level. Requirements synthesis focuses on creating a balanced set of required operational capabilities satisfying user's needs and concept of operations. Requirements are evolved from capability based languages to function based language by statistical exploration and engineering design which are derived in the following order: concept alternative, concept baseline, initial baseline and functional baseline. The early-phase naval ship design process can be divided into three passes: concept definition, concept exploration and concept development. Main activities and outcomes in each pass are shortly presented. Concept definition is the first important step that produces a concept baseline through extensive design space exploration promptly. Design space exploration applies a statistical approach to explore design trends of existing ships and produce feasible design range corresponding to concept alternative. It further helps naval systems engineers and operational researchers by inducing useful responses to user and stakeholders' questions at a sufficient degree of confidence and success in the very early ship design. The focus of this paper is on the flow of design space exploration, and its application to a high-speed patrol craft. The views expressed in this paper are those of the authors, and do not reflect the official policy or rule of the Navy.