• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.1
• /
• pp.93-100
• /
• 2014

Steel reinforcement buried in concrete structure in submerged zone does not easily become corroded due to lack of dissolved oxygen. For that reason, accelerated corrosion test in submerged state is performed with an electrochemical method, which is not suitable for actual corrosion mechanism and makes it difficult to find relevance with long-term behavior. In this study, accelerated corrosion test was performed with the temperature and chloride concentration as main variables in order to establish a method for accelerated corrosion test in submerged zone. Corrosion was determined by the result of reinforcement corrosion monitoring based on galvanic potential measurement and half-cell potential method. The accelerated corrosion test result showed that temperature had the most dominant influence. To determine the chloride content, chloride concentration by depth in the test sample was measured. With the same conditions, chloride penetration interpretation was performed by DuCOM, a FEM durability interpretation program. Also, a test was performed to measure dissolved oxygen according to soaking conditions of artificial seawater, which was used for verifying the validity of the accelerated corrosion test result.

• Journal of Advanced Navigation Technology
• /
• v.18 no.5
• /
• pp.483-489
• /
• 2014

Proposed electronic ballast circuit for harmonic reduction includes adding lossless snubber circuit to DC-DC converter. To get inverter for changing DC-AC, a lamp has been changed to equivalence resistance in the standard lamp voltage and current data, also inverter circuit has been interpreted by being changed to R, L, C equivalence circuit. Using converted equivalent circuit, the most suitable circuit constant which can satisfy the characteristics of fluorescent lamps has been decided on and finally designed. It could not only eliminate distortion waveform from pulsation frequency in inverter direct side current but also reduce considerably pulsation rate and switching loss by making input current of inverter discontinuous. The validity for the results of this study has been verified through the experiment to measure harmonic occurrence after applying a newly-manufactured product of electronic ballast to 40 W line tube style fluorescent lamps.

• The KIPS Transactions:PartB
• /
• v.14B no.4
• /
• pp.263-272
• /
• 2007

This paper proposes a skeleton-based hierarchical shape description scheme, called a skeleton tree, for accurate shape-based image retrieval. A skeleton tree represents an object shape as a hierarchical tree where high-level nodes describe parts of coarse trunk regions and low-level nodes describe fine details of boundary regions. Each node refines the shape of its parent node. Most of the noise disturbances are limited to bottom level nodes and the boundary noise is reduced by decreasing weights on the bottom levels. The similarity of two skeleton trees is computed by considering the best match of a skeleton tree to a sub-tree of another skeleton tree. The proposed method uses a hybrid similarity measure by employing both Fourier descriptors and moment invariants in computing the similarity of two skeleton trees. Several experimental results are presented demonstrating the validity of the skeleton tree scheme for the shape description and indexing.

• Archives of design research
• /
• v.11 no.2
• /
• pp.275-284
• /
• 1998

It's required to develop new design process which reflects objective and quantative data of real market structure and consumers' demand and to understand, use statistical packages and softwares for it in order to make a product design which can satisfy consumr's needs. Product design approachs have, however, merely focused on simple methods of design and have not been improved much so far with regards to customer-oriented design. Therefore, This study aims to help customer-oriented product design with validity and reliability by suggesting successful product design process based on reviewing existing literatures and by providing each steps of design process with optimal approaches reflecting consumers' preference. The results of this study may provide all design related fields with theoretical framework of successful design process and may reinforce competitive ability of design with the development of customer-oriented design process. We need to verify vality of this study by doing some case studies with various products in real market situations and need to develop measurements and survey methods to measure exact customers' perception dimensions.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.3
• /
• pp.87-93
• /
• 2008

The large scale shaker can be employed to measure linear and nonlinear shear moduli of soils in situ as a function of shear strain. The method involves applying dynamic loads on a surface foundation measuring the dynamic response of the soil mass beneath the foundation with embedded instrumentation. This paper focuses on the development of a framework of the inverse analysis for the interpretation of test data to estimate linear and nonlinear shear moduli of soils along with the necessity of the inverse analysis. The suggested framework is based on the nonlinear least squares but it uses two iterative loops to account for the nonlinear behavior of soil that sensors are not located. The validity of the suggested inversion framework is tested through a series of numerical parametric studies. An example use of the suggested inversion framework is also shown. Because the field condition may affect the accuracy of suggested method, it is important to conduct a preliminary inverse analysis to quantify the discrepancy between the estimated modulus and the baseline.

• Journal of Digital Convergence
• /
• v.13 no.12
• /
• pp.325-336
• /
• 2015

The purpose of this study is to confirm the components of users' shared value expectation(SVE) on lifelong education through convergent approaches. After reviewing primary data and collecting secondary data with quantitative and qualitative research methodologies, the components of users' SVE on lifelong education were categorized into 10 perspectives, 27 measured variables, and 81 questions. After conducting a confirmatory factor analysis, the latent measurement model was confirmed as reasonable. Internal reliability, construct convergent discriminant validity were also confirmed as reasonable. In a viewpoint that builds interdisciplinary theory, this research may help grasp users' SVE on lifelong education with interdisciplinary approaches. In a strategic viewpoint, this study may contribute to both understanding categorized users' value expectation and planning/executing suitable programs that can meet the expectations. In a managerial viewpoint, this result may help measure the effectiveness of SVE on lifelong education quantitatively.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.6
• /
• pp.513-519
• /
• 2016

In this study, dynamic vertical displacement of liquid in the tuned liquid column damper(TLCD) is measured by a laser Doppler vibrometer(LDV) to overcome limitations of existing sensors and to leverage noncontact sensing. Addressing advantages of noncontact measurements, operational principles of the LDV to measure velocity and displacement of a target object in motion is explained. The feasibility of application of the LDV to measurement of liquid motion in the TLCD is experimentally explored. A series of shake table tests with the TLCD are performed to determine requirements of application of the LDV. Based on the experimental results, it is proved that the LDV works under the condition of adding dye to the liquid by increasing the intensity of reflected laser and thus validity is verified by comparison with a conventional wave height meter.

• The Transactions of the Korea Information Processing Society
• /
• v.1 no.2
• /
• pp.194-201
• /
• 1994

Recently, as application fields of software is extended, relative importance of software make a gradual increase and importance of development cost is being increased. However, as former evaluation model of development cost evaluate at the functional point of view for the most part, at this paper, I intend to propose evaluation model of software development cost COSMOS-Q(COSt MOdel for Subcontract-Quality) which one evaluate also in quality as well as function. The model proposed in this paper set the goal at software orderer evaluate software cost exactly with only order specification information. At this paper, I proposed cost evaluation model and evaluated it's validity refering to review result in ISO/SC7 about a software quality feature with extraction of quality feature factor which produce change of cost and set up the evaluation measure adoptable as order condition.

• Journal of Aerospace System Engineering
• /
• v.13 no.1
• /
• pp.47-53
• /
• 2019

To improve an aerodynamic characteristic of the eVOTL aircraft, Korea Aerospace Research Institute (KARI) performed a validity test of the cross-rotating propeller technology. First, CFD analysis was carried out and an idea of the cross-rotating propeller to imply on a multi-copter confirmed with a commerce pitch control multi-copter that has two different blades, 0.11 and 0.21 m. After verifying the idea, a multi-copter with about 3 kg maximum take-off weight (MTOW) was custom designed to complete a ground test to measure thrust and noise. The test was performed with 15 and 22 in. propellers at the identical tip speed. The test results show that the 22 in. propeller with the cross-rotating technology required about 30 % less power and reduced 3~5 dB aerodynamic noise as compared to 15 in. propeller without cross-rotating.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.31 no.1
• /
• pp.40-46
• /
• 2011

In the field application of the conventional acoustic nonlinear technique using through transmission of bulk waves to evaluate the contact acoustic nonlinearity(CAN) in solid-solid contact interfaces like as in the closed crack, it has difficulty to access inner position for attaching the pulsing or receiving transducer. In the present study, a new reflection technique has been suggested to measure the acoustic nonlinearity in solid-solid contact interfaces, which uses both of pulsing and receiving transducers on the same side of target and so that it will be very useful for the field application. For this, based on the linear and the nonlinear contact stiffness estimated by the power-model of the contacting pressure, the nonlinear parameter of the reflected ultrasonic wave at the interfaces has been theoretically calculated. Experimental results in contact interfaces of A1606l-T6 alloy specimens with loading pressure showed good agreement with the theoretical predictions, which proves the validity of the suggested reflection mode technique.