• Journal of the Korean Electrochemical Society
• /
• v.10 no.3
• /
• pp.184-189
• /
• 2007

The importance of secondary battery industry is getting excited according to the development of battery industry as a high efficiency energy supplier of electronic machine of mobile information such as mobile phone, lap-top computer, PDA. It is rasing the interest about security of safety and high efficiency of cathode material for main part of secondary lithium battery. The cathode material which has been used like $LiCoO_2,\;LiMn_2O_4,\;LiNi_xCo_yMn_zO_2,\;LiNi_xCo_yM_zO_2$ (M=Al, Zr, Mg etc.,) the most typical material is $LiCoO_2$. But it is studying the development of substitute such as efficiency amelioration of $LiCoO_2$, thetiary element, olivine element because of the capacity of $LiCoO_2$, the matter of security; especially the betterment of efficiency, security research of safety has been actively processed in domestic and overseas about surface coating treatment of active cathode which is using oxide ($M_xO_3$). This study analyses side effect of battery according to increase of surface treatment, formation of precipitation for reagent condensation, non-reagent residue of oxide ($M_xO_3$) which is remains during the surface treatment of $LiCoO_2$; conducts study of new process, the consideration of the electrochemical property to improve oxide solution of mixing rate, mixture of surface treatment, dryness, calcinations conditionetc.

• The Journal of Society for e-Business Studies
• /
• v.25 no.1
• /
• pp.65-82
• /
• 2020

Start-ups often use crowdfunding platforms such as Wadiz to get financing from corporate investors and general public. These platforms include functions to increase participant activity through the number of comments, interest and online word-of-mouth. This study aims to elucidate how these functions related to a participant activity exhibit mediating effects on a success of crowdfunding and an achievement rate of targeted investment amount. To this end, the individual variables such as progress period, target amount, venture company, experience of attracting investment, possession of intellectual property rights, a career of the representative and an award experience of the representative were classified into the project characteristics, the company characteristics and the representative characteristics through not only previous studies but also interviews with investment professionals and platform operators. Afterwards, this study went through an empirical verification process using a structural equation model that has both crowdfunding performance and participant activity, which is the independent and mediating factors of three perspectives, as well as the dependent variables. In other words, this study analyzes how the characteristics of three perspectives affect the participant activity and how the participant activity had the mediating effects on the crowdfunding performance. In addition, it derives how the analysis results mentioned above vary according to business types (internet services, culture/art, manufacturing/distribution) and investment styles (stock type and bond type). It is expected that this study will help not only in deriving the factors affecting the performance of an investment type crowdfunding but also in preparing the measures to increase a participant activity.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.8
• /
• pp.962-968
• /
• 2013

Problem of greenhouse gases associated with global warming and the world rise in fuel oil prices due to the depletion of fossil fuel has attracted attention. For this reason, maritime transport business, has shown interest in green-ship technology to reduce the consumption of fuel and reduce greenhouse gas for environmental protection. Power system of the ship is one of the most important factors for safe operation. Therefore, at design of ship power system, most of existing vessel used comparative large capacity generator in order to respond peak load such as bow thruster, crane and etc. In the navigation of ship, marine generators most would be operated at low load operation. In the low load operation of the generation rate of 50% or less, the operation efficiency of the generator it deteriorated, to consume more fuel oil. It also, it means that adversely effect the life of the generator. In this paper, studied how to apply for a secondary battery in container ship that relatively frequent arrival and departure in port. As a result, in order to apply the secondary battery to increase the operating efficiency of the generator during the voyage, it was confirmed that it is possible to reduce fuel consumption.

• Tunnel and Underground Space
• /
• v.14 no.1
• /
• pp.69-77
• /
• 2004

Investigation of the time-dependent behavior of rock and the associated mechanisms are of key interest in long-term stability analysis of many engineering applications. In this study, creep tests were performed on Daejeon granite samples of 25.4mm diameter under uniaxial compression at varying stress levels. The effect of moisture was investigated by testing both air-dried and fully water-saturated samples. The creep behavior of Daejeon granite exhibited three distinctive stages of primary, secondary and tertiary creep. The ultimate strength of granite under a constant stress decreased considerably with time. Saturation and immersion of the test specimen in water markedly increased the total creep strain as well as the secondary creep rate. The experimental creep curves are fitted to Burger's model as well as two other empirical models suggested by previous researchers. A number of the parameters determined for each model are dependent on stress and influenced by the presence of water. Based on the experimental results, an empirical relation between the applied stress and the time-dependent strain is established separately for each air-dried and fully water-saturated Daejeon granite.

• Journal of Korea Soil Environment Society
• /
• v.4 no.2
• /
• pp.127-136
• /
• 1999

In the past several years phytoremediation, defined as the use of plants for removing contaminants from media such as soils or water, has attracted a great deal of interest as a potentially useful remediation technology We attempted to assess the effectiveness of phytoremediation of diesel-contaminated soils in a green house. Screening test for selecting an appropriate plant was performed by observing the harmful effects of diesel dosage on the growth of 4 plants. Alfalfa was selected as a potentially useful plant among corn and barnyard grasses due to its high tolerance to the toxicity of diesel in growth. Bioremediation of the artificial diesel-contaminated soil packed in the PVC columns(0.3m in diameter $\times$ 1m in length) with air supplied, alfalfa planted, and alfalfa and air supplied was investigated for 100 days. The results of the column test showed plant effects on enhancing the biodegradation of diesel in the contaminated soils compared to the control column which had no plant. Injecting air to the columns during phytoremediation also showed additional effects on the removal rate of diesel. Comparison of microbial activity in each test column showed a beneficial effect of plants in the soil remediation processes. This results can be explained microbial activity in rhizosphere is a crucial factor for removing diesel.

• The Korean Journal of Nuclear Medicine
• /
• v.29 no.1
• /
• pp.48-53
• /
• 1995

This study investigates a simple mathematical model for the quantitative estimation of regional myocardial blood flow in experimental canine coronary artery thrombosis using Rb-82 dynamic myocardial positron emission tomography. The coronary thrombosis was induced using the new catheter technique by narrowing the lumen of coronary vessel gradually, which finally led to partial obstruction of coronary artery. Ten Rb-82 dynamic myocardial PET scans were performed sequentially for each experiment using our 5, 10 and 20 second acquisition protocol, respectively, and three regions of interest were drawn on the transaxial slices, one on left ventricular chamber for input function and the other two on normal and decreased perfusion segments for the flow estimation in those regions. Single compartment model has been applied to the measured sets of regional PET data, and the rate constants of influx to myocardial tissue were calculated for regional myocardial flow estimates with the three parameter fits of raw data by the Levenberg-Marquardt method. The results showed that, (1) single compartment model suggested by Kety-Schmidt could be used for the simple estimation of regional myocardial blood flow, (2) the calculated regional myocardial blood flow estimates were dependent on the selection of input function, which reflected partial volume effect and left ventricular wall motion, and (3) mathematically fitted input and tissue time activity curves were more suitable than the direct application of the measured data in terms of convergence.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.8
• /
• pp.5212-5222
• /
• 2015

The purpose of this study is to analyze the structural relation among consciousness of lifelong education, leadership and life core competencies. The subjects were 607 university students who participated in the courses of the lifelong educator in Daejeon, Chungnam and Chungbuk province. As the results of the study, first, university students' consciousness of lifelong education had positive effects on their life core competencies. Second, university students' consciousness of lifelong education had positive effects on their leadership. Third, university students' leadership had positive effects on their life core competencies. Forth, university students' leadership had mediating effect between consciousness of lifelong education and life core competencies. In other words, university students' consciousness of lifelong education influences their leadership, and then it influences their life core competencies positively. These results can be used to change university students' consciousness of lifelong education and to develop their leadership and life core competencies. In addition, the results present that their participation rate can be increased through continuous interest and participation after their graduation. The study has a realistic point to operate lifelong educator training courses and lifelong education of university, so it is meaningful to provide the theoretical and practical implications for developing lifelong education.

• Journal of Periodontal and Implant Science
• /
• v.38 no.2
• /
• pp.163-170
• /
• 2008

Purpose: Biphasic calcium phosphates have been of great interest recently. Mixing adequate ratios of hydroxyapatite(HA) and beta-tricalcium phosphate($\beta$-TCP) allowed to control the resorption rate without distorting its osteoconductive property. This study evaluated the bone formation effect of newly developed biphasic calcium phosphate(BCP) in calvarial defect of rabbits. Materials and Methods: 6 male New Zealand rabbits were used. Four defects with 8mm in diameter were created on each animal. BCP with HA/$\beta$-TCP ratio of 7:3 and particle size of $0.5{\sim}1.0\;mm$ was used as the test group and bovine bone with $0.25{\sim}1.0\;mm$ particle size, as the control group. Both test and control group materials were randomly implanted in the calvarial defects and were covered witha polymer membrane. The animals were sacrificed after 12, 24, and 48 weeks of implantation under general euthanasia. Resin blocks were obtained and were stained by masson's trichrome for histological observation. Results: Overall results were uneventful without any defect exposure or inflammation. The amount of new bone formation and bone maturity increased with increase in healing period at both groups. New bone in test group was mostly formed along the material particle surrounded by osteoblasts, and observation of osteoblastic stream was also present. Bone maturity increased as it was closer to thedefect margins. Under the same healing period, the test group showed more bone formation than the control group with more stable bovine bone particles remaining even after 48 weeks, whereas considerable resorption took place in BCP. Almost total defect closure was observed in test group with new bone formation in the central part of the defect. However, limited new bone formation was observed in the control group. Conclusion: Within the limits of the study, the present study reveals the newly developed BCP to be a good osteoconductive material. However, further studies are needed to be conducted in a different study model with a larger sample size.

• The Journal of the Convergence on Culture Technology
• /
• v.6 no.4
• /
• pp.483-492
• /
• 2020

Considering the fact that many students and parents spend a considerable amount of time and economic power on prior learning and that the environments of internet-based society change rapidly, it is worth examining the status and effectiveness of prior learning. In response, the study surveyed 186 first-year students of A high school in Changwon on the basic status of science prior learning. By the analysis results for the status, 39.8% of the students surveyed said they had experience in prior learning in science. Among the students experienced, 56 students who started science prior learning after the start of winter vacation in the third grade of middle school were analyzed the specific status of science prior learning and the impact of science prior learning on science achievements. The semi-subject form of pre-learning in science showed the highest response rate with 50.0 percent, and the motivation for pre-learning in science was the highest with 33.9 percent improvement in test scores. The confidence and learning intention were positive when conducting prior learning in a semi-subject form, and interest and value were positive when conducting prior learning in a self-directed form. As a result of the survey on the effect of science prior learning, 71.4% of the students who experienced science prior learning showed positive scientific achievement.

• Journal of Korean Society of Transportation
• /
• v.28 no.2
• /
• pp.135-150
• /
• 2010

This paper focuses on finding out which covenants are different among the concession agreements of Korean BTO projects and how these influenced IRR(Internal Rate of Return). That is, to figure out the political and economical determinants of IRR by analyzing the concession agreements which are the basic contract of implementing projects. As IRR is an index of profitability, so spread is an indicator of risk to collect debts. That's the reason why the analysis of spread is included. For the empirical analysis, the data of concession agreements for 75 projects and financial models are used. These 75 concession agreements are contracted from 1995 to 2008. The dependent variables are after tax nominal IRR and the spread of long term interest rates of 75 BTO projects. The independent variables are project's proceeding factors, the feasibility variables, the variables related to financial character and the variables related to covenants or the government's policy. The analysis shows that IRR has been influenced by the equity level of financial investors, the national government managed projects, the projects with minimum revenue guarantee (MRG), etc. And the equity level of financial investors, the national government managed projects and the implementation of supplementary project have an effect on spread also.