• Korean Journal of Construction Engineering and Management
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• v.21 no.5
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• pp.20-28
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• 2020

In construction project, an error in quantity information immediately leads to an error in the quotation, highly reliable quantity calculation is required for successful performance of a project. But there is a difficulty in the current situation for the person in charge to review all calculation sheets for quantity review as the quotation work has to be performed in a short period of time. Accordingly, it is thought that a review plan is required to secure reliability on calculated results and the review plan should be able to be carried out within insufficient quotation periods. In the present paper, it is intended to present a plan that enables quantity to be reviewed with the minimum number of persons within the shortest period of time through an algorithm of calculating a verification quantity. The suggested algorithm allows the result of quantity calculation work carried out earlier based on 2-dimensional drawing to be compared, not with an accurate quantity, but within an error range.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.9
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• pp.599-608
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• 2022

Urban air mobility (UAM) equipped with rotor system is subject to ground effect at vertiport during takeoff and landing. The aerodynamic performance of the aircraft in ground effect should be analyzed for the safe operation. In this study, The ground effects on the aerodynamic performance and wake structure of the quadcopter electric vertical takeoff and landing (eVTOL) configuration equipped with coaxial counter-rotating propellers were investigated by using the lattice Boltzmann method (LBM). The influence of the ground effect was observed differently in the upper and lower propellers of the coaxial counter-rotating propeller system. There was no significant change in the aerodynamic performance of the upper propeller even if the propeller height above the ground was changed, whereas the averaged thrust and torque of the lower propeller increased significantly as propeller height decreased. In addition, the amplitude of the thrust fluctuation tended to increase as the propeller height decreased. The propeller wake was not sufficiently propagated downstream and was diffused along the ground due to the outwash flow developed by the ground effect. The impingement of the rotor wakes on the ground and a fountain vortex structure were observed.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.1-8
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• 2009

This thesis has analyzed the effect of the surge happening in flight on the engine performance, especially on the PW4000 turbofan engine. It is to be judged that the flight surge can occur more often at the time of takeoff than it does en route due to the fact that the engine parameters are prone to fluctuate. EPR is judged to be the most highly sensitive parameter responding when surge occurs. Both Engine rpm and Wf decrease almost simultaneously just like an EPR. During the take-off rolling, N1 vibration is more sensitive than the N2 vibration. Consequently, the surge can be detected by EGT increase, while the other parameters (EPR, rpm, Wf, etc) decrease.

• Journal of the Korea Institute of Building Construction
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• v.13 no.5
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• pp.506-512
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• 2013

Since the amendment of the law on the private sector investment in social infrastructure in January of 2005, the government has been actively promoting Build-Transfer-Lease (BTL) projects. Notably, most new educational facilities have been built as BTL projects. For these facilities, the unit cost per unit area has been applied to predict construction costs. However, since construction costs are mostly managed after the detailed design phase, the costs can be estimated incorrectly. For this reason, cost management is needed in the planning phase, with a sound approximate estimate to prevent the wasteful use of funds. To address this shortcoming, this study aims to develop a quantity prediction model for education facilities using regression analysis in the planning phase. The developed model is focused on the required quantities of reinforced concrete and bricks. In order to achieve the objective, the data of 44 educational facility projects collected from Gyeonggi-do was used in the regression model. This study can be utilized by major stakeholders to accurately predict construction costs by estimating the appropriate quantities of reinforced concrete and bricks in the planning design phase.

• Journal of the Korean Society for Library and Information Science
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• v.46 no.1
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• pp.119-139
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• 2012

Due to the inferior condition of local library reference service, an air of indifference about users, and the increase in Internet resources, cooperative reference service in domestic libraries tend to be stagnant. The increase in Internet resources was reconsidered, aside from traditional library reference service, based on question and answer service. It shed new light on the importance of indirect service, which is focused on reliable knowledge base construction. This study analyzed cooperative reference service, which is managed by the Japanese Diet library that pursued indirect service contrary to ours. Based on that, it suggested a new takeoff possibility for Korean cooperative reference service.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.81-91
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• 2017

The performances of lifting surfaces are particularly critical in specific flight conditions like takeoff and landing. Different systems can be used to increase the lift and drag coefficients in such conditions like slat, flap or ailerons. Nevertheless they increase the losses and make difficult the mechanical design of wing structures. Morphing surfaces are a compromise between a right increase in lift and a reduction of parts movements involved in the actuation. Furthermore these systems are suitable for more than one flight condition with low inertia problems. So, flap and slats can be easily substituted by the corresponding morphing shapes. This paper deals with a genetic optimization of an airfoil with morphing flap with an already optimized nose. Indeed, two different codes are used to solve the equations, a finite volume code suitable for structured grids named ZEN and the EulerBoundary Layer Drela's code MSES. First a number of different preliminary design tests were done considering a specific set of design variables in order to restrict the design region. Then a RANS optimization with a single design point related to the take-off flight condition has been carried out in order to refine the previous design. Results are shown using the characteristic curves of the best and of the baseline reported to outline the computed performances enhancements. They reveal how the contemporary use of a morphing acting on the nose of the main component and the trailing edge of the flap drive towards a total not negligible increment in lift.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.226-233
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• 2015

Pose estimation is an important operation for many vision tasks. This paper presents a method of estimating the camera pose, using a known landmark for the purpose of autonomous vertical takeoff and landing(VTOL) unmanned aerial vehicle(UAV) landing. The proposed method uses a distinctive methodology to solve the pose estimation problem. We propose to combine extrinsic parameters from known and unknown 3-D(three-dimensional) feature points, and inertial estimation of camera 6-DOF(Degree Of Freedom) into one linear inhomogeneous equation. This allows us to use singular value decomposition(SVD) to neatly solve the given optimization problem. We present experimental results that demonstrate the ability of the proposed method to estimate camera 6DOF with the ease of implementation.

• Journal of Korea Game Society
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• v.11 no.4
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• pp.3-14
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• 2011

In this paper, affection of jumping motion factors on visual effects are studied for game character's natural motion realization. First, 3 kinds of games that realize natural motions are selected and 4-types of characters jumping motions are captured from it. Then, the motions are measured using four fundamental principles of jumping as takeoff strength, landing impact, landing elasticity and flexibility, and measured in motion factors as time, distance, angle either. Finally, consistent characteristics of visual effects and motion factors on jumping motion are suggested. The study could be used to basic information for realization of character's natural jumping motion.

• Korean Institute of Interior Design Journal
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• v.25 no.6
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• pp.70-78
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• 2016

This paper aims to describe a case study of parametric interior design based on BIM (Building Information Modeling). As the practical use of BIM-based design grows, its influence expands into the field of interior architecture design. BIM makes possible to check various design plan, reach decision making in an effective way, and change design plan in an efficient method. Therefore, BIM is also promising field in interior architecture design. However, compared to other fields in architecture, engineering, and construction (AEC) industry, there have been less research and projects on BIM in the field of interior architecture. For increasing the feasibility of adapting BIM in interior architecture design, this paper describes a case study-projecting images for designing interior panels using parametric modeling. This process needs elaborate, delicate, and precise steps for harmonious output. For continuous use of building, users look forward to the design which variable and changeable according to user's preference and environment. Therefore, demand for parametric design in the interior design part such as panel pattern design for various decoration is growing. Treated process in this paper deals with an advanced phase which much effective in decreasing time consumption and useless part of process. Finally, this paper suggests the possibility of using BIM in the interior design process and field where BIM can be applied.

• Journal of Advanced Navigation Technology
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• v.14 no.4
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• pp.479-488
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• 2010

The aim of this paper is to research the change in the turbulent flow and the AOA occurred by the wind perpendicular to the direction of runway according to the three-dimensional numerical analysis. The maximum amplitude of AOA variation on runway reached $6^{\circ}$ within 1 second because of the wake formed by the constructions in the vicinity of the airport. The overall effects appeared in aperiodic forms. It was also observed the rapid flow generated between the buildings shifted into the existing wake and eventually merged with it. It is expected thai the strong wake will cause instability during takeoff and landing.