• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.397-398
• /
• 2010

This study analyzed fire resistance characteristics of high strength concrete followd by changes of mixing rate in organic fibers of PP, NY and CL. PP+NY+CL=0.02+0.01+0.02 was better than the mixing of other fibers in fire resistance characteristics.

• Applied Chemistry for Engineering
• /
• v.9 no.7
• /
• pp.1065-1069
• /
• 1998

This study was investigated to improve peformance of carbon negative electrode for lithium ion secondary battery. The carbon electrode was prepared by mixing with graphitic carbon material, natural graphite, and nongraphitic carbon material, petroleum cokes, which was heat-treated at $700^{\circ}C$ for l hour. Its electrochemical and charge-discharge characteristics were tested according to mixing ratio of different two types of carbon material. The carbon electrode prepared with various mixing ratio showed both charateristcs of two different types of carbon materials and the best characteristics as carbon electrode was demonstrated at mixing ratio of 1:1.

• Journal of Science Education
• /
• v.33 no.1
• /
• pp.69-76
• /
• 2009

Probabilistic reasoning and combinational reasoning are essential to build a logical thinking and a process of thinking dealing with everyday life as well as scientific knowledge. This research aims at finding the optimal period to teach reasoning to the students who haven't developed probabilistic reasoning and combinational reasoning. The treatment program was performed for 20 students from each grade who couldn't develop two parts of reasoning. The treatment program using baduk stones and cards was performed repeatedly, focusing on the specific activities. After four weeks of treatment program, the test to check the development of probabilistic reasoning and combinational reasoning was performed again and the changes of reasoning development were identified. After giving treatment program for reasoning development, 15.0%, 25.0% and 40.0% of improvement in the 4th, the 5th, the 6th graders respectively were shown. With regard to the combinational reasoning, the results showed the improvement of 20.0% in the 4th grades, 25.0% in the 5th graders and 63.2% in the 6th graders. As a result of research in the above, students, who were not formed probabilistic reasoning and combinational reasoning, could be known to be enhanced through learning, but to fail to be formed the qualitative change like the cognitive development. It is expected that this research can contribute to the improvement of students' cognitive level and there would be more active researches in different fields to improve the cognitive level of the 6th graders who are in their optimal periods to learn two parts of reasoning.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2004.11a
• /
• pp.289-295
• /
• 2004

The objective of this paper is to analyze the equipment combination of stevedoring system at port container terminal. In general, the productivity of container terminal is evaluated by productivity of container cranes at apron, but there are other equipment such as transport vehicles and yard cranes. Therefore, a method that can estimate the optimal equipment combination of stevedoring system in container terminal is required. We perform various simulation experiment and analyze equipment combination to improve the productivity. From the application of the case study, we demonstrated the savings effect using mean waiting time rates by the equipment combination.

• The Korean Journal of Applied Statistics
• /
• v.32 no.3
• /
• pp.331-348
• /
• 2019

Understanding the tumor heterogeneity due to differences in the growth pattern of metastatic tumors and rate of change is important for understanding the sensitivity of tumor cells to drugs and finding appropriate therapies. It is often possible to test for differences in population means using t-test or ANOVA when the group of N samples is distinct. However, these statistical methods can not be used unless the groups are distinguished as the data covered in this paper. Statistical methods have been studied to test heterogeneity between samples. The minimum combination t-test method is one of them. In this paper, we propose a maximum combinatorial t-test method that takes into account combinations that bisect data at different ratios. Also we propose a method based on the idea that examining the heterogeneity of a sample is equivalent to testing whether the number of optimal clusters is one in the cluster analysis. We verified that the proposed methods, maximum combination t-test method and gap statistic, have better type-I error and power than the previously proposed method based on simulation study and obtained the results through real data analysis.

• Journal of the Korea Concrete Institute
• /
• v.23 no.4
• /
• pp.405-411
• /
• 2011

Using combinations of carbon and glass fiber composites normally used for strengthening of concrete structures, the hybrid effect from strengthening concrete structures using the composite is studied. To produce the hybrid effects, the specimens were made with optimum proportions of carbon fibers with glass fibers. Then, direct tensile tests were conducted on the hybrid FRP (fiber reinforced polymer) specimens. Unlike the woven fiber sheet currently used in construction sites, the FRP specimens have to be directly combined with the fibers, which make the work very complicated. Therefore, direct tensile test specimens manufacturing method based on the combination of high-tension carbon fibers and E-type glass fibers was proposed and the effects of hybridization is studied through the direct tensile test. By comparing the ductility index, the modulus of elasticity, and the stress-strain curves of the specimens, the most optimum glass to carbon fiber combination ratio for the hybrid FRP was found to be 9 to 1 with ductile K-type epoxy. The study results are discussed in detail in the paper.

• Journal of the Korea Institute of Building Construction
• /
• v.20 no.2
• /
• pp.113-121
• /
• 2020

Lots of soil-pavement concrete placed showed a number of problems such as decreasing strength, and durability. In this research, to provide a solution of the problem reported the wasting materials of natural organic lime and magnesia lime were used as a hardener to achieve sufficient performance of soil-pavement concrete. Namely, as a stimulus of blast furnace slag, the natural organic lime and magnesia lime were tested within the mix proportion of 0 to 10 % for each lime to make a new hardener. As a result, in the case of mortar with 1 to 3 % of cement to fine aggregate, 30 % replaced blast furnace slag showed the more favorable results with 5 to 5 % of mix proportion for natural organic lime and magnesia lime.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.7
• /
• pp.56-63
• /
• 2016

This paper presents a novel method for detecting a ghost key at the membrane type keyboard, which has additional resistive coating to the membrane film. Also, the optimal ratio of resistances for detecting a ghost key was designed based on the characteristics of the membrane film. The optimal ratio of resistances was considered to be able to detect the worst case (i.e., difference voltage between normal key and ghost key is minimum). The ability of the proposed methods are evaluated by simulation studies in this paper. In order to verify the proposed method, the experiment was carried out with a designed circuit and A/D (analog to digital) in MCU (micro controller unit). The proposed method is implemented into the membrane type keyboard and is verified by experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.1B
• /
• pp.16-23
• /
• 2009

This paper investigates how many optimal routes can be established in terms of a given wireless mesh routing metric. Although many of routing metrics have been devised to precisely derive the wireless link quality in mesh, most (if not all) metrics have not been evaluated their optimality along with routing protocols. We consider stateof-the-art routing metrics and a widely accepted routing protocol in order to observe the optimality of established routes varying the number of source nodes. Also, we propose a unidirectional routing to deal with possible link asymmetry feature in wireless links. Through comparative simulation evaluations, we show that the portion of optimally established routes becomes less as the network traffic load increases, regardless of employed metrics, network topologies, and routing protocols.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.59 no.4
• /
• pp.521-525
• /
• 2014

This study was conducted in the central northern area that has a smaller production of winter forage crop compared to the southern areas, in order to identify the optimal mix of seeding, mix ratio and seeding method. The results showed that among the mixed seeding of triticale and crimson clover, the mix of triticale+crimson clover, mixing ratio is 8:2 (w/w), had the largest dry weight of 1,462 kg/10a, which was more than either single seeding of triticale or crimson clover. Although there were no total quantity differences between different mix ratios, there were differences in quantity between sowing types with broadcasting seeding is more than in narrow strips seeding. In forage value of mixed seeding combination, crude protein contents in single seeding of crimson clover showed the highest value at 17.2%, and in single seed of triticale showed the lowest at 7.4%. In mixed seeding combination the crude protein contents were highest in triticale+crimson clover, mixing ratio is 7:3 (w/w), at 9.0%. The mixed seeding between triticlale and legume crops will helpful for increasing forage value.