• Journal of Chest Surgery
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• v.32 no.11
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• pp.989-997
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• 1999

Background: Calcific degeneration is the major cause of clinical failure of glutaraldehyde (GA) crosslinked bioprosthetic tissues implanted in the body and necessitates the reoperation or causes death. Surface modification of biologic tissues using sulfonated polyethyleneoixde (PEO-SO3) has been suggested to significantly enhance blood compatibility, biostability and calcification-resistance by means of the synergistic effect of highly mobile and hydrophilic PEO chains and electrical repulsion of negatively charged sulfonate groups. This study was designed to evaluate the anticalcification effect of surface-modification of biologic arteries by direct coupling of PEO-SO3 after GA fixation and changes of calcification according to the implantation period through the quantitative investigation of the deposited calcium and phosphorous contents of the biologic arterial tissues in the canine circulatory implantation model. Material and Method: Total of 16 fresh canine carotid arteries were harvested from eight adult dogs and divided in to GA group(n =8) and PEO-SO3 group(n=8). Sulfonation of diamino-terminated PEO was performed using propane sultone. Canine carotid arteries were only crosslinked with 0.65% GA solution in GA group and modified by direct coupling 5% PEO-SO3 solution after GA crosslinkage for 2 days and stabilized by NaBH4 solution for 16 hours in PEO-SO3 group. In both groups the resected segment of bilateral carotid arteries were reconstructed. Reconstructed segments of the two groups were analysed the quantities of calcium and phosphorous contents after 3(n=4) and 6(n=4) weeks in vivo. Result: After implantation of 3 seeks, PEO-SO3 group showed significantly less depositions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.884-891
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• 2020

The collapse of bridges can cause massive casualties and economic losses. Therefore, it is thus essential to evaluate the structural safety of bridges. For this task, structural reliability analysis, considering various bridge-related uncertainty factors, is often used. This paper proposes a new computational platform to perform structural reliability analysis for bridges and evaluate their structural safety under various loading conditions. For this purpose, a software package of reliability analysis, Finite Element Reliability Using MATLAB (FERUM), was integrated with MIDAS/CIVIL, which is a widely-used commercial software package specialized for bridges. Furthermore, a graphical user interface (GUI) control module has been added to FERUM to overcome the limitations of software operation. In this study, the proposed platform was applied to a simple frame structure, and the analysis results of the FORM (First-Order Reliability Method) and MCS (Monte Carlo simulation), which are representative reliability analysis methods, were compared. The proposed platform was verified by confirming that the calculated failure probability difference was less than 5%. In addition, the structural safety of a pre-stressed concrete (PSC) bridge was evaluated considering the KL-510 vehicle model. The proposed new structural reliability analysis platform is expected to enable an effective reliability-based safety evaluation of bridges.

• The KIPS Transactions:PartD
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• v.13D no.1 s.104
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• pp.67-74
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• 2006

The security requirements identification in the software development has received some attention recently. However, previous methods do not provide clear method and process of security requirements identification. We propose a process that software developers can build application specific security requirements from state transition diagrams at the security threat location. The proposed process consists of building model and identifying application specific security requirements. The state transition diagram is constructed through subprocesses i) the identification of security threat locations using security failure data based on the point that attackers exploit software vulnerabilities and attack system assets, ii) the construction of a state transition diagram which is usable to protect, mitigate, and remove vulnerabilities of security threat locations. The identification Process of application specific security requirements consist of i) the analysis of the functional requirements of the software, which are decomposed into a DFD(Data Flow Diagram; the identification of the security threat location; and the appliance of the corresponding state transition diagram into the security threat locations, ii) the construction of the application specific state transition diagram, iii) the construction of security requirements based on the rule of the identification of security requirements. The proposed method is helpful to identify the security requirements easily at an early phase of software development.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.164-172
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• 2015

As the petroleum products produced from the Oil refinery industry (ORI), a national key industry in Korea, are supplied to other industries as an intermediate goods, the supply shortage of ORI has a large impact on the national economy. This paper attempts to analyze the supply shortage effects which are defined as the negative impact of one won of supply failure in the ORI on the production of other industries. To this end, an inter-industry analysis using an input-output (I-O) table describing inter-industry flow of intermediate goods is applied. More concretely, the supply-driven model is employed over the period 1990-2012. In addition, the results are compared with those for shipbuilding, semiconductor, and steel industries. The results show that the supply shortage effects are computed to be 0.9205 won when using 2012 I-O table. More specifically, the supply shortage effects on chemical products and transportation industries are computed to be 0.2113 and 0.1140, which are relatively large, The supply shortage effect of ORI is smaller than that of steel industry (1.4131 won), but larger than that of shipbuilding industry (0.0586 won) and that of semiconductor industry (0.1111 won).

• Journal of Distribution Science
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• v.17 no.2
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• pp.53-69
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• 2019

Purpose - National scientific technology R&D investment is exceeding 60 trillion won per year, and the results of patent applications and technology transfers are visually improving. However, despite the improving research results of national R&D, the practical results of technology startups are mediocre. It is now time to expand the construction of the technology commercialization ecosystem, where the expansion of national R&D leads to the results of technology startups. Therefore, this study discussed the measures to increase the competitiveness of technology startups through the factual survey of the companies that benefitted from R&D support programs. Research design, data, and methodology - This study targeted 996 companies that benefitted from the R&D projects of the Technology Transfer Center for National R&D Programs, and deducted itemized issues through the survey replies. Survey questions were prepared to estimate the national R&D results, and the technology recognition path, the purpose of detailed introduction of the technology, investment of the commercialization fund, economic results, and the factors of success and failure were analyzed. Results - As for the recognition rate of technology during the process of corporate technology commercialization through the technology transfer, recognition through project participation showed a high response rate, and diverse implications of technology commercialization were deducted through the analysis of economic results. As for the resolution alternatives, the proliferation of technology commercialization platform that can create excellent technology for the companies in early stages and the measure of expanding the distribution of technology infrastructure were suggested. In this study, public technology commercialization strategy is established, and the innovative marketing strategy is presented. Conclusions - This study reveal that the result of creating scientific technology jobs should be deducted, in order to produce the revolutionary results of job creation by suggesting the success models of technology commercialization based on domestic scientific technology. In particular, even though the support systems for public research results are being diversely suggested, accurate studies on their actual conditions are currently lacking. Therefore, this study suggest realistic political alternatives to assure results in the process of public technology commercialization, by examining the current state of public research results of R&D support institutions and diagnosing the issues.

• Journal of Biomedical Engineering Research
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• v.38 no.1
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• pp.9-15
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• 2017

Recently, flexible cages have been introduced in an attempt to absorb and reduce the abnormal load transfer along the anterior parts of the spine. They are designed to be used with the pedicle screw systems to allow some mobility at the index level while containing ROM at the adjacent level. In this study, a finite element (FE) study was performed to assess biomechanical efficacies of the flexible cage when combined with pedicle screws with flexible rods. The post-operated models were constructed by modifying the L4-5 of a previously-validated 3-D FE model of the intact lumbar spine (L2-S1): (1) Type 1, flexible cage only; (2) Type 2, pedicle screws with flexible rods; (3) Type 3, interbody fusion cage plus pedicle screws with rigid rods; (4) Type 4, interbody fusion cage plus Type 2; (5) Type 5, Type 1 plus Type 2. Flexion/extension of 10 Nm with a compressive follower load of 400N was applied. As compared to the Type 3 (62~65%) and Type 4 (59~62%), Type 5 (53~55%) was able to limit the motion at the operated level effectively, despite moderate reduction at the adjacent level. It was also able to shift the load back to the anterior portions of the spine thus relieving excessively high posterior load transfer and to reduce stress on the endplate by absorbing the load with its flexible shape design features. The likelihood of component failure of flexble cage remained less than 30% regardless of loading conditions when combined with pedicle screws with flexible rods. Our study demonstrated that flexible cages when combined with posterior dynamic system may help reduce subsidence of cage and degeneration process at the adjacent levels while effectively providing stability at the operated level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5893-5900
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• 2012

It is very critical to promptly maintain airway of cardiac arrest cases or serious traumatic cases. The purpose of this study is to compare intubation rate, successful rate and pre-/post-education self-confidence between laryngeal tube (LTS) and proseal laryngeal mask (PLMA), so that it may contribute to improving the ability of 119 emergency team - a pivotal role in pre-hospitalization process - to carry out advanced airway management. In order to achieve the purpose, total 60 paramedics (Class I) who worked for incumbent 119 emergency team were asked to join a practical experiment and were also divided into two groups (LTS group: 30 people, PLMA group: 30 people). In details, they were all asked to take 3 sessions of practice (5 minutes per session) using dummy model to quantitatively measure the time and success/failure of intubation and the change of their self-confidence. As a result, it was found that there were statistically significant differences in the time of intubation between LTS and PLMA group (p=.000), but there was no significant difference in the rate of successful intubation between these two groups, and self-confidence of two groups tended to significantly increase after experiment (p=.000). Conclusively, if it is necessary to promptly apply intubation to traumatic cases with immobilized cervical vertebral and lingual edema, LTS can be useful as an effective means of intubation. And it is expected that continuing intubation training using LTS will improve the ability of emergency team to perform advanced airway management for traumatic cases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.579-584
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• 2017

The damper oil seal of a high-speed railway vehicle is made from nitrile butadiene rubber (NBR) in order to prevent lubricant from leaking into the damper and to stop harmful contaminants from entering the external environment while in service. Oil leakage through the seal primarily occurs from fatigue failure of the damper. Cumulative damage of the seal occurs due to the contact force between the rod and the rubber during movement due to track irregularities and cants, among other factors. Thus, the design of the oil seal should minimize the maximum principal strain at weak points. In this study, the optimal cross section of the damper oil seal was found using the multi-island genetic algorithm method to improve the durability of the damper. The optimal shape of the oil seal was derived using process automation and design optimization software. Nonlinear material properties for finite element analysis (FEA) of the rubber were determined by Marlow's model. The nonlinear FEA confirmed that the maximum principal strain at the oil leakage point was decreased 24% between the initial design and the optimum design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.537-544
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• 2017

An experimental study was carried out to investigate the characteristics of the propagation distance of a flood wave considering the levee failure speed in a flat inundation area. The Ritter solution for one dimensional flow was considered to formulate the experimental results and a representative form with coefficients of k and m, which consider the three dimensional flow characteristics, was applied. The experiments showed that the propagation velocity of the wave front in the inundation area was influenced by the levee breach speed as well as the initial water level, which is a significant variable representing the flood wave behavior. In addition, coefficients k and m are not constants, but variables that vary with levee breach speed. An empirical formula was also suggested using the experimental results in the form of the relationships between k and m. In this study, a large-scale experiment for flood inundation was carried out to examine the behavior of flooding in the inundated area and the relationships between the levee breach speed and wave-front propagation velocity were suggested based on the experimental results. These research results are expected to be used as the baseline data to draw a flow inundation map, establish an emergency action plan, and verify the two-dimensional numerical model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2600-2606
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• 2012

Purpose: This study was conducted to examine the effect of simulation-based training on the clinical competence and confidence of nursing students in intravenous injection performance and the satisfaction of clients. Methods: This study employed a randomized control posttest non-synchronized design. The participants were 90 second-year nursing students(31 multimedia group, 28 IV model group, 31 IV computerized systems group) of S-University in Seoul, Korea. Each group was given 30 minutes for five trial injections, then the students performed intravenous injections on the back of hands of the clients, and the results were measured. Results: There were significant differences in competence of clinical performance among the three groups showed no significant differences in confidence before and after intravenous injections. While there was no significant difference in the satisfaction of clients among the three groups, there were significant differences in the satisfaction of clients resulting from the success or failure of intravenous injections(p=<.001). Conclusion: This study shows that simulation-base training contributes to the enhancement of competence and confidence of nursing students in clinical performance. It would be helpful to use various simulation-based training media as another choice of education in different fields.