• Wind and Structures
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• v.12 no.6
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• pp.553-574
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• 2009

This paper presents statistical analysis results of wind speed and atmospheric turbulence data measured from more than 30 anemometers installed at 15 different height levels on 325 m high Beijing Meteorological Tower and is primarily intended to provide useful information on boundary layer wind characteristics for wind-resistant design of tall buildings and high-rise structures. Profiles of mean wind speed are presented based on the field measurements and are compared with empirical models' predictions. Relevant parameters of atmospheric boundary layer at urban terrain are determined from the measured wind speed profiles. Furthermore, wind velocity data in longitudinal, lateral and vertical directions, which were recorded from an ultrasonic anemometer during windstorms, are analyzed and discussed. Atmospheric turbulence information such as turbulence intensity, gust factor, turbulence integral length scale and power spectral densities of the three-dimensional fluctuating wind velocity are presented and used to evaluate the adequacy of existing theoretical and empirical models. The objective of this study is to investigate the profiles of mean wind speed and atmospheric turbulence characteristics over a typical urban area.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.171-176
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• 2014

The polarization characteristics of ultracompact polarization-insensitive directional coupler (PIDC) based on double sandwiched rib-type waveguide are explored in detail by using longitudinal modal transmission-line theory (L-MTLT). To obtain the polarization-insensitive condition of ultracompact directional coupler, the coupling length and coupling efficiency as functions of the refractive index and thickness of sandwiched rib-type waveguide are analyzed for quasi-TE and quasi-TM modes. The numerical results show that the ultracompact polarization-insensitive coupler with hundreds of micrometer scales is realized by properly choosing structural and material parameters of double sandwiched layers. Furthermore, the influence of fundamental mode profile, which is distributed in lateral waveguide of coupler, on the coupler performance has been investigated.

• Smart Structures and Systems
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• v.21 no.5
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• pp.537-548
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• 2018

A tunnel deformation monitoring system is developed with the use of fiber Bragg grating (FBG) sensing technique, aiming at providing continuous monitoring of railway tunnel deformation in the long term, and early warning for the rail service maintainers and authorities to avoid catastrophic consequences when significant deformation occurs. Specifically, a set of FBG bending gauges with the ability of angle measurement and temperature compensation is designed and manufactured for the purpose of online monitoring of tunnel deformation. An overall profile of lateral tunnel displacement along the longitudinal direction can be obtained by implementing an array of the FBG bending gauges interconnected by rigid rods, in conjunction with a proper algorithm. The devised system is verified in laboratory experiments with a test setup enabling to imitate various patterns of tunnel deformation before the implementation of this system in an in-service high-speed railway (HSR) tunnel.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.128.2-128.2
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• 2011

Experiments to study high-energy cosmic rays (CRs) employ Monte Carlo codes for extensive air shower (EAS) simulations to figure out the properties of CRs. COSMOS and CORSIKA among EAS simulation codes are currently being used to analyze the data of the Telescope Array experiment. We have generated a library of about 10,000 simulated EASs with the primary energy ranging from $10^{18.5}eV$ to $10^{20}eV$ and the zenith angle of primary particles ranging from 0 to 45 degree for proton and iron primaries. We have compared the results predicted by CORSIKA and COSMOS under the same condition. In this talk, we show the differences in the energy spectra at the ground, the longitudinal shower profile as a function of atmospheric depth, the Calorimetric energy, and the Xmax distribution. We also discuss the lateral distribution function obtained from GEANT4 simulations which is being used to measure the detector response.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.11a
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• pp.75-79
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• 2006

Recently, more highly effective construction materials are needed for the reasonable and economical structure system is required as the construction structures become more multi storied, large-sized and diversified. That is to say, the highly qualified concrete is positively promoted as a part of plan to establish the effective space according to the dead load of structures and diminish of segment profile and to build up the economic structures. However, the high strength concrete has the problems such high brittleness and low ductility. Specially, for the high strength concrete, it has different strength from normal concrete as the internal temperature goes up steadily due to high heat of hydration by the quantities of highly level of cement, so the concrete which is mixed with various miscible materials is used. As the development and study for high strength concrete (more than $100N/mm^2$) is under way actively and the strength of high strength concrete increases, the strength different from the existing high strength concrete of ten than $100N/mm^2$, but the study for this is not adequate and indefinite. In addition, the study and report to apply the strength expression and analysis results of internal structure. Therefore, this study is an experiment about using the miscible materials affects what happens to the longitudinal physical property.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.9
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• pp.669-678
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• 2007

In this study, the ventilation characteristics is investigated numerically of the longitudinal ventilation method in the curved long road tunnel. Numerical work has been conducted for the jet fan location by utilizing the commercial finite-volume code, FLUENT. Configuration of the tunnel is three-lane, 1600 m long, $120m^2$ in area, 3000 m curvature radius. The velocity profile, distribution of mono-dioxide carbon and flow rate of air are examined in the tunnel. Through the analysis, it is found that the difference of ventilation flow rate Is a little by the jet fan location, but tunnel outlet setup (CASEIII) of jet fans is the most efficient concerned with CO concentration.

• The Mathematical Education
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• v.57 no.4
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• pp.393-412
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• 2018

Teacher quality is a key factor that determines quality of education. Being aware of this, the Korean government and teachers have been striving to improve teachers' professionalism. Research about the impacts of efforts to enhance teacher professionalism on students' academic achievement and course satisfaction, however, is extremely limited. This study sought to advance our understanding of the relationship between these factors by analyzing what teacher characteristics impact students' achievement and satisfaction. To this end, the study drew on the middle and high school data from 3rd to 6th year survey of the Seoul Educational Longitudinal Study. Structural equational modeling were used as the main approach. Latent profile analysis, a kind of mixture modeling analysis, were used as needed. This study found that teachers' participation in instruction enhancement activity and professional development impact students' attitude toward mathematics lessons and their perception on class atmosphere, and ultimately impact their academic achievement as well as their overall satisfaction in the course. In addition, teachers' use of EBS textbooks and videos impact 3rd grade high schoolers' academic achievement. These findings suggest that effort to improve teacher professionalism positively impact students' academic achievement and course satisfaction, although there is a difference according to the year grade. This study provides implications for education policy makers and teacher educators.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.772-785
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• 2021

Container ships has a transverse section in the form of an open profile, making it very sensitive to torsion phenomena. To minimize this effect, a structure known as a torsion box exists, which is subject to high stresses influenced by the fatigue phenomenon and the existence of cut-outs, for the passage of the longitudinal stiffeners, acting as stress concentrators. The aim of this study is to propose a two-stage design methodology to aid designers in satisfying the structural requirements and contribute with to a better understanding of the considered structure. The transverse webs of a torsional box structure are examined by comparing different cut-out geometries from numerical models with different regular load conditions to obtain the variables of the fatigue safety factor through linear regression models. The most appropriate geometry of the torsion box is established in terms of minimum weight, from nonlinear multivariable optimization models.

• Asia-Pacific Journal of Business
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• v.11 no.4
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• pp.1-19
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• 2020

Purpose - This study analyzes the intertemporal patterns in personnel decisions made between a supervisor and a subordinate to understand potential supervisor bias in the decisions. A correlation between the current and the most recent personnel decisions made for a subordinate by a current supervisor captures certain relationship-embedded and time-invariant factors in effect. The characteristics speak to the nature of a supervisor bias arising from a relationship, or favoritism. Design/methodology/approach - This study manually collects the executive profile data from annual reports of key Samsung Group affiliates and compile a longitudinal sample of 3,675 executive-years. It mainly explores the logistic regression analysis. Findings - The study finds that a supervisor' previous promotion award to a subordinate does not improve but decreases the likelihood of promotions in ensuing years, suggesting the containment of favoritism; and that the time since the last promotion award to a subordinate by the current supervisor increases the likelihood of both promotions and dismissals of the subordinate. Research implications or Originality - The findings are generally consistent with the theory suggesting that incentive schemes that align interests between an individual and an organization will contain the form of a supervisor bias.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.2
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• pp.48-60
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• 2000

This study is aimed to clarify the distribution chracteristics of marine terraces and extract the specific surface at Gampo-eup, Gyeongju city on the map of 1:5,000 using GIS. The effects and problems occurred on the process of using GIS were investigated for the research of marine terrace. The longitudinal profile analysis was carried out along the 12 sections on the geomorphic surfaces of the study area, and actually High higher surface(HH-surface) was found over 100m a.s.l., which has not been reported till now. And the occupancy rate could be calculated by substitution on the height between 4m and 87m a.s.l. for each mean slope degree $1-5^{\circ}$ obtained from the actual measuring along four sections. Consequently the lower-I surface was highly reliable to use as the key bed for studying marine terraces. The accurate and detail analysis about the marine terraces is able to be accomplished on the basis of meaningful actual measuring, though its general possible distribution area can be extracted from GIS with the less effort. Namely the quantified results obtained from GIS could offer the basis for the objective analysis of the geomorphic surfaces. And we can look over the landscape and investigate the surfaces with reliefs effectively in relation to the real geomorphology on the study area, where in situ approach is difficult. But the digital map with a large scale should be offered first of all in order to raise the accuracy of the analysis.