• Journal of the Korean Ceramic Society
• /
• v.43 no.1 s.284
• /
• pp.4-9
• /
• 2006

To test the fracture toughness of alumina; a Surface-Crack-in-Flexure (SCF) method, a Single-Edge-Precracked-Beam (SEPB) method and a Single-Edge-V-Notched-Beam (SEVNB) method were used at crosshead rates ranging from 0.005 mm/min to 2 mm/ min and relative humidity ranging from $15\%\;to\;80\%$. The results show that the fracture toughness tested by the SCF method increases with either an increasing loading rate or decreasing relative humidity; in contrast, the toughness by the SEPB method and the SEVNB method does not depend on the loading rate or the relative humidity. Theoretical analysis of the way slow crack growth affects the apparent fracture toughness indicates that the three testing methods have different effects with respect to the loading rate and the relative humidity; moreover, these differences are attributable to differences in the size of the cracks or notches.

• Korean Journal of Remote Sensing
• /
• v.33 no.5_1
• /
• pp.495-506
• /
• 2017

This study was carried out to effectively perform relative color correction for high-resolution aerial ortho image. For this study, relative geometrical error between adjacent images was analyzed. The block sum method is proposed to reduce the relative geometrical error. We used the regression coefficients determined based on the block sum size to perform the color correction. As a result, it was confirmed that the relative color correction was visually performed well. Quantitative analysis was performed through histogram similarity analysis. It is proved that block sum method is useful for relative color correction. Particularly, the block sum size was very important to correct color based on the amount of relative geometrical error.

• Geomechanics and Engineering
• /
• v.14 no.2
• /
• pp.131-139
• /
• 2018

The preparation of repeatable and uniformly reconstituted soil specimens up to the specified conditions is an essential requirement for the laboratory tests. In this study for large samples replication, the simultaneous usage of the traveling pluviation and curtain raining technique is used to develop a new method, called the curtain travelling pluviator (CTP). This simple and cost effective system is based on the air pluviation approach, whilst reducing the sample production time, can reproduce uniform samples with relative densities ranging from 25% to 96%. In order to investigate the resulting suitability and uniformity from the proposed method, a series of tests is performed. The effect of curtain traveling velocity, curtain width, drop height, and flow rate on the parameters of the sample is thoroughly investigated. Increase in the curtain velocity and drop height leads to the increase in relative density for the sand specimen. Increase in curtain width typically resulted in the reduction of relative density. Test results reveal that the terminal drop height for the sand specimen in this study is more than 500 mm. Relative density contour lines are presented that can be utilized in optimizing the drop height and curtain width parameters. Sample uniformity in the vertical and horizontal orientation is investigated through the sampling containers. Increasing relative density tends to result in the higher sample repeatability and uniformity.

• KIEAE Journal
• /
• v.12 no.4
• /
• pp.21-30
• /
• 2012

This study aims to set up Energy self-sufficiency urban planning system responding climate change by reducing fossil energy consumption and carbon emission, and to suggest effective application method. This study has 3 levels. First, it defines energy self-sufficient city responding climate change theoretically. Second, it set up planning system of Energy Self-sufficient city responding climate change. Third, ANP method was applied to introduce priority of application according to relative importance of planning section. As ANP method has to construct network to show interrelation among elements, 1st questionnaire survey was carried out to figure out interrelation. 2nd questionnaire survey introduced to judge relative importance of planning aspects and sections. In conclusion, this study shows interrelation among planning sections. By considering the relative importance, Energy environment and Energy consumption was derived as important planning aspects, and Architecture, Landuse, and Production of renewable energy was estimated as s important planning elements.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1998.04a
• /
• pp.141-148
• /
• 1998

The chloride attack of the top mat of reinforcing bars is a major cause of deterioration of comcrete deck of plate girder bridges. This is caused by a current design method which requires a top mat of reinforcing bars to resist a negative bending moment in bridge decks. In recently, empirical evidence has indicated that the top transverse reinforcing bars can patially or fully be eliminated without jeopardizing the structural integrity of a deck. So, one of the most efficient way to increase durability of concrete deck of bridges is the development of new design method that reduce or eliminate the top mat reinforcing bars, mad it is possible by the exact analysis that considering the negative bending moment reducing effect which introduced by relative deflection of plate girders. In this study, we develop the new bridge deck analysis method that considered the effect of relative girder deflection by applying the principles of slope deflection method of frames, and that is fine tuned with results of finite element analysis. This new approach evaluate a bending moment in a deck based on the effect of relative girder deflection as well as the magnitude of wheel loads, the girder spacing and stiffness, deck stiffness and the span length

• Korean Management Science Review
• /
• v.22 no.1
• /
• pp.1-13
• /
• 2005

This paper proposed a quantitative evaluation method to measure the operational effectiveness of the local military manpower administrations. The proposed method compared the relative operational effectiveness level for 12 local military manpower administrations in Korea.. The method used the IDEA (imprecise Data Envelopment Analysis) model which Is able to measure relative operational effectiveness level, and also used two input variables (labor cost, operational cost) and three output variables (number of military applicants, number of civil application approved & processed, management accuracy level). Through the model output analysis, we presented the relative effectiveness scores, the reason for non-effectiveness, and the relationship between non-effective ness level and input/output variables for each local military manpower administration. We also presented a few recommendations how to improve the effectiveness level on particular local military manpower administration.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.147-152
• /
• 1992

This paper describes a new approach that can extract the relative shift vectors between two aerial image sequences for implementing the visual navigation system. This method minimizes the noise included in the aircraft attitude information that represents the changes of the aircraft attitude using the statistical method and Kalman Filtering method. This result can be used to find the relative shift vectors which are independent of the attitude changes indicating the true trajectories of aircraft. We applied this method to the image about which we had already known the information of aircraft attitude, and that result showed that the errors were minimized successfully.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.157-159
• /
• 2003

To improve power quality, it is important to find the location of disturbance source. This paper presents a method to find the location of disturbance source that leads to voltage sag. The relative location of the source is defined and the method to determine the relative location of voltage sag is proposed. With this method, this paper shows that the location of disturbance source can be identified under distributed monitoring system.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.52 no.4
• /
• pp.223-232
• /
• 2003

This paper presents a new method driving multiple robots to their goal position without collision. Each robot adjusts its motion based on the information on the goal location, velocity, and position of the robot and the velocity and position of the .other robots. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the following factors: the distance from the robot to the other robots, velocity of the robot and the other robots. To implement the concept in moving robot avoidance, relative distance between the robots is derived. Our method combines the relative distance with an artificial potential field method. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, the usual potential field method sometimes fails preventing collision or causes hasty motion, because it initiates avoidance motion later than the proposed method. The proposed method can be used to move robots in a robot soccer team to their appropriate position without collision as fast as possible.

• Journal of the Korean Data and Information Science Society
• /
• v.20 no.2
• /
• pp.349-356
• /
• 2009

In this study, we suggest the estimation method of the relative risk for the unemployment statistics of a small area such as si, gun, gu in Korea. The considered method are the usual pooled estimator, weighted estimator with the inverse of log-variance as weights, and the Jackknife estimator. And we compare with the efficiency of the three estimators by estimating the bias and mean square errors using real data from the 2002 Economically Active Population Survey of Gyeonggi-do. We compute the unemployed rate of male and female in small areas, and then estimate the common relative risk for the unemployed rate between male and female. Also, the stability and reliability of the three estimators for the common relative risk was evaluated using the RB(relative bias) and the RRMSE(relative root mean square error) of these estimators. Finally, the Jackknife estimator turned out to be much more efficient than the other estimators.