• The Journal of Korean Academy of Prosthodontics
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• v.42 no.3
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• pp.307-326
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• 2004

Statement of problem. The long-term success of implants is the development of a stable direct connection between bone and implant surface, which must be structural and functional. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. Among them, altering the surface properties can modify cellular responses such as cell adhesion, cell motility and bone deposition. Purpose. This study was to evaluate the cellular behaviors on the surface-modified titanium by morphological observation, cellular proliferation and differentiation. Material and methods. Specimens were divided into five groups, depending on their surface treatment: electropolishing(EP) anoclizing(AN), machining(MA), blasting with hydroxyapatite particle(RBM) and electrical discharge machining(EDM). Physicochemical properties and microstructures of the specimens were examined and the responses of osteoblast-like cells were investigated. The microtopography of specimens was observed by scanning electron microscopy(SEM). Surface roughness was measured by a three-dimensional roughness measuring system. The microstructure was analyzed by X-ray diffractometer(XRD) and scanning auger electron microscopy(AES). To evaluate cellular responses to modified titanium surfaces, osteoblasts isolated from neonatal rat were cultured. The cellular morphology and total protein amounts of osteoblast-like cell were taken as the marker for cellular proliferation, while the expression of alkaline phosphatase was used as the early differentiation marker for osteoblast. In addition, the type I collagen production was determined to be a reliable indicator of bone matrix synthesis. Results. 1. Each prepared specimen showed specific microtopography at SEM examination. The RBM group had a rough and irregular pattern with reticulated appearance. The EDM-treated surface had evident cracks and was heterogeneous consisting of broad sheet or plate with smooth edges and clusters of small grains, deep pores or craters. 2. Surface roughness values were, from the lowest to the highest, electropolished group, anodized group, machined group, RBM group and EDM group. 3. All groups showed amorphous structures. Especially anodized group was found to have increased surface oxide thickness and EDM group had titaniumcarbide(TiC) structure. 4. Cells on electropolished, anodized and machined surfaces developed flattened cell shape and cells on RBM appeared spherical and EDM showed both. After 14 days, the cells cultured from all groups were formed to be confluent and exhibited multilayer proliferation, often overlapped or stratified. 5. Total protein amounts were formed to be quite similar among all the group at 48 hours. At 14 days, the electropolished group and the anodized group induced more total protein amount than the RBM group(P<.05). 6. There was no significant difference among five groups for alkaline phosphatase(ALP) activity at 48 hours. The AN group showed significantly higher ALP activity than any other groups at 14 days(P<.05). 7. All the groups showed similar collagen synthesis except the EDM group. The amount of collagen on the electropolished and anodized surfaces were higher than that on the EDM surface(P<.05).

• Journal of the Korean GEO-environmental Society
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• v.21 no.4
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• pp.19-30
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• 2020

This numerical study is to investigate the seepage characteristics of the side of the structure in the event of leakage from the structural connection part of the drainage structure installed through the enlarged levee, and to analyze the effect of piping on the stabilization of the levee by the lateral penetration behavior. To take into account lateral seepage behavior, 2D and 3D numerical analyses were performed on the same model, and the effect of lateral seepage was analyzed to assess the validity of the numerical analysis. As a result, when leakage occurs and a lateral seepage is considered with the gate located on the riverside land, the maximum pore water pressure near the leakage point of the structure has been reduced by half compared to the normal seepage state where no leakage occurred. Excessive variation in the pore pressure was shown at the lower part of the structure, especially if lateral seepage is not considered. As a water level rises to the high water level, it shows the hydraulic gradient was larger than the critical hydraulic gradient, which will be vulnerable to long-term piping. If a gate is located in the inland and side seepage is not considered, the effect of the seepage water such as hydraulic gradient and seepage velocity is underestimated compared with the case of considering side seepage. The maximum hydraulic gradient is relatively small when lateral seepage is neglected if a gate is located in the riverside land and there was might be a risk of piping or loss of material. In addition, the period exceeding the critical hydraulic gradient was interpreted as a short time zone. As a result, it is considered that the possibility of piping can be underestimated if side seepage is ignored.

• Journal of Environmental Science International
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• v.26 no.2
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• pp.231-238
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• 2017

Rapid industrial development has led to a serious problem of pollution in the industrial sector. With the increasing social need for environmental protection, research on air pollution prevention equipment for reducing pollutants in industrial processes is actively being undertaken. The deterioration of existent, installed facilities, their increased emission rates, and the strengthening of the effluent quality standards make complying with permissible emission standards difficult. In fact, installing new electric precipitators or complementing existent facilities is inevitable. The expansion and complementation of the installed electrical precipitators have led to improvements in dust collection efficiency, shorter working times, and lower costs. Because of its easy installation and simple manufacturing process, the production method with the discharge electrode of an electric precipitator is widely used. The following conclusions were reached by classifying discharge electrodes into four types based on the production method and mutually comparing them by their dust collection efficiency. None of the four types used in this study were damaged by impact. However, we were able to confirm some strain from the compression sites of both type A and type B. Both type B and type C are expected to have greater dust collection efficiencies than the other models due to their large vibration transmissibility. Moreover, the high vibrational energy is expected to cause rapping damage during its operation. Particularly, in the case of type B, some of the strain was found at the end of the compression site. The coupling schemes of both type C and type D are out of vibration transmissibility. On the other hand, the ability to maintain straightness and solidity of the side is regarded as outstanding and stable. Type D has outstanding on-site workability, considering the presence of locking, structural stability, and work conditions. From these experiments, we determined that type C is the most ideal connection method of discharge electrode, considering its construction period of renovation. Type C is inferior to type D with regard to on-site workability. However, type C has outstanding dedusting transmission with regard to the straightness, solidity maintenance, and vibration of shearing stress.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.402-410
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• 2017

The effect of the steel pipe member joint on the design performance of a plastic multi-span greenhouse was analysed through the comparing full-scale experiment and numerical analysis. The design performance of the greenhouse is generally evaluated through numerical analysis, but it is rare to consider the characteristics of the connections or joints of the members. In this study, the effect of the column-gutter beam-rafter-wind break wall joint on the design performance of the whole structure of a plastic multi-span greenhouse was analysed. The numerical results with assuming that the member joint are rigid condition were compared with the full-scale load test results using member joints used in the field. The stiffness of the entire structure was compared using the load-displacement relationship and the change of the load sharing ratio that the main members such as column, rafters, and wind break wall was analysed. The results of the load test were about 40% larger than the numerical result and the member stress was more than twice as large as those of the loaded columns. In order to increase the reliability of the design performance of the greenhouse, it is necessary to develop a numerical analysis model which can consider the characteristics of various joints.

• Journal of the Korea Society of Computer and Information
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• v.17 no.10
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• pp.185-192
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• 2012

Call Center requires an ability of agents a lot more than face-to-face contact due to being achieved communication by non face-to face channel for contact with customers. In order to improve the ability of agents, Call Center carries out various educational training according to their work experience and function and with the accomplishment of educational training, Call Center is going to fulfill to develop its quality of counseling and productivity. On the other hand, due to investment of a lot of time and budget to educational training, it is needed to grasp and manage about its effectiveness that how helpful the training is for performance of work-site operations through evaluation of educational training. Having Seen researches about evaluation of educational training until these days, most researches have mainstream to measure satisfaction and a level of learning or degree that how the learning transfers to actions. It is found that a research about an entire evaluation model should be required. This study aims to investigate effectiveness of Call Center educational training from the level of recognition by reflecting Kirkpatrick's the four levels of learning evaluation. By the four levels, reaction, learning, behavior and results, the study found out a connection with standards of evaluation about each levels. In addition, by using structural equation modeling, it was examined goodness of fit about the entire model. Furthermore, by an alternative model, considering a direct relation between a factor of reaction and behavior, it was compared and examined goodness of fit of overall model of the study model and the alternative one.

• Journal of Korean Society of Steel Construction
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• v.22 no.2
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• pp.109-119
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• 2010

There are many restrictions in the application of high-strength HSSs, including yield strength and yield ratio for the 600-MPa steel. The AISC and Canadian codes recommend that the yield strength and yield ratio of HSS members be 360 MPa and 80%, respectively. It is important to understand the true buckling behaviors of HSSs using high-strength steel at the limit states. There are many experimental data regarding the rectangular HSSs, and the circular ones are not enough for high-strength steel. Therefore, this study was conducted to create a better understanding of the buckling behaviors of the 600- and 400-MPa steels based on the results of the finite-element analysis that was done before the experiment. To understand the structural behaviors of the aforementioned steels, the width-to-thickness ratios, the angle of the web members, the yield strength, and the gap of the web members were selected as the main parameters in this study, and ABAQUS, a general finite-element program, was used.As a result, the compression web member reached elastic buckling in the 600-MPa steel and inelastic buckling in the 400-MPa steel. A brittle fracture occurred in the case where the yield ratio was greater than 80%. At the same time, it was found that the limit strength determined via FEM analysis had a higher value compared to the code evaluation with the variation of the width-to-thickness ratio in the main code member. The change in the connection load in high-strength steels was not identified by the other factors.

• International Journal of Advanced Culture Technology
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• v.5 no.3
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• pp.11-23
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• 2017

Anatomy is one of the basic subjects of the nursing course, which is included in the curriculum of the nursing. Anatomy is a basic course for understanding major in nursing and it is the first gateway to acquire expertise. It is mainly opened in nursing and first to second grades. Therefore, students who have advanced to the nursing department have great interest and expectation on the anatomy subjects. In general, nursing students are studying anatomy with theories and models, and some universities practice on tour after dissection of medical consortium for short time. This is called the Cadaver practice. This study was carried out to investigate the thoughts and experiences of bioethics through nursing students' Cadaver practice. The interview data were processed through the analysis and interpretation process using the phenomenological research method, Giorgi method. As a result, 48 semantic units were derived, and then they were divided into 10 subcomponents and divided into 6 categories. As a result of the analysis, the experience of nursing students' bioethics was tied to the topic of six questions. For example, 'what about the respect and responsibility of nursing students in Cadaver?', 'What about your experience with the Cadaver experiment and bioethics?', 'What was the academic achievement of the actual human body structure viewing experience with cadaver?', 'What was the connection with theory?', 'What was your intention to recommend to others?', 'What was your perception and interest in the Cadaver experiment?'. Analyzes were integrated into 10 structures; "Thank you for your donation", "want others to refuse donation", "Burden of practice", "Good opportunities for learning", "Understand better", "Should study harder", "Memory is better", "Compared to theory", "Good experience", "Want to rejoin". The general structural description of the participants' meanings is summarized as follows. Nursing college students who participated in the Cadaver had a gratitude for the donor, but they said they would like to talk to others about donating organs. Before they went to practice, they felt a lot of pressure on the dissection of the cadaver, but they went to the practice and thought that it was a good opportunity to learn by doing well. Specifically, they understood that they had better understanding than the theoretical lesson, and that they were more eager to study their major through practice. In other words, most of them were more memorable and they would like to participate again if the opportunity comes next time. The results of this study show that the practice of Cadaver in nursing college students is very positive in terms of educational effectiveness. However, in terms of bioethics, it can be seen that the education process is somewhat unsatisfactory. Therefore, the systematic bioethics education should be prepared before the practice in the nursing college students' Cadaver practice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4648-4659
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• 2011

Korea experienced rapid urbanization due to high growth of economy. As people left the country and gathered in the city, the size of city has been expanded, resulting in unbalanced development of the land. In addition, it appears in diverse aspects from nationwide phenomenon to the local development in each city unit. In particular, it even tends to become social problems in the metropolitan cities. As a solution for it, this study conducts theoretical consideration on sustainability in the aspect of balanced urban development and suggests measures through analysis on Siheung-city. The result is as follows. First of all, comprehensive approach is required based on sustainability. It is required to derive balanced city development by expanding it to the social, cultural and economic aspects. Second, integrated management policy is required for the original city along with new development. It should be considered together with diverse social and physical aspects. Third, approach from the aspect of city planning is required through consideration on flat city expansion and connection with city space structural. Fourth, in order to foster balanced urban development, it is needed to grope for solutions for imbalanced urban development through the participation of diverse groups such as local residents, private enterprisers, and the non-profit civic groups of the local community along with the mediation among persons interested. And continuous support of administrative authorities should be obtained to create such environment.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.609-619
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• 2004

An investigation was conducted on the activities around Europe in order to solve the problem of the thermal bridging of steel studs, which had caused a significant disadvantage. This study included the following: diminishing the contact area between the studs and the sheathing, lengthening the heat transfer route, replacing the steel web with a less conductive material, and placing foam insulation in locations where the thermal shorts are most critical. Although energy efficiency is usually the focus of such foreign cases because their stud application is mostly limited to low-rise residential buildings, both structural and thermal performance are taken into consideration in this study because these target middle-story buildings. A hybrid stud composed of steel and polymer was also developed. This hybrid stud, which is 150 SL in size, is made of a galvanized steel sheet (SGC58) and a glass fiber reinforced polymer (GFRP) withepoxy bonding. A total of 32 specimens were manufactured. Its parameters comprise two types of connection detail,s: the thickness of steel (1.0mm and 1.2mm) and of the GFRP (4mm-4ply and 6mm-6ply), and the ratio of the length to the depth (L/D = 3, 6, 9, 12). Steel stud specimens with the same conditions were compared to the hybrid stud. The test revealed that in the case of the steel specimen with a thickness of 1.0mm, the maximum load of hybrid studs increased an average of 1.62 times comparedto that of the steel stud. In the case of the steel specimen with a thickness of 1.2mm, on the other hand, the average increase was 1.46times. All specimens showed full composite action until the collapse.

• Korean Journal of Social Welfare
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• v.66 no.1
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• pp.163-189
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• 2014

The public perceptions about the cause of the poverty are generally considered as the important subject because they are assumed to have profound influences on the anti-poverty strategies, the features of the welfare system, and the welfare politics. Yet, there have been few studies on the public perceptions about attributions for poverty in Korea. In this article, we explore the popular perceptions about the causes of the poverty and investigate the determinants of the various beliefs about the causes of the poverty in Korea. The data derive from the Welfare Attitudes data of the 8th Korea Welfare Panel Survey. The results indicates that Koreans are more likely to support the individualistic explanations on the causes of the poverty than the structural and the fatalistic explanations. The results of regression model analysis show that there are differences in the determinants of the three types of poverty explanations, but subjective variables have the strong effects on all of the poverty explanations in Korea. In this study we find that Koreans are more likely than the western european welfare states to endorse individualistic explanations. These findings suggest that the underdevelopment of the welfare system in Korea is assumed to have the connection with the popular individualistic explanations. And, they suggest that there are needed to have notices to changing the public perceptions of the poverty and the cultural context of the social welfare in order to advance the welfare state in Korea.