• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.737-752
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• 1992

Analysis of elasto-dynamic deformation of flexible linkage mechanism is conducted using the finite element method. The equations of motion of the system are derived from the static structural problem in which dynamic inertia, gravitational and driving forces are treated as external loads. Linear spring model is included in the formulation of equation of motions to represent the effects of deformation of elastic bearings of revolute joints on the system behavior. A computer program is constructed and applied to analyze a specific crank-lever 4-bar mechanism. The algorithm of the program is as follows. First, the natural frequencies and the mode shapes of the system are calculated by solving the eigenproblem of the mechanism system which can be considered as a static structure by assuming the input shaft (crank shaft) to be fixed at any given configuration of mechanism. And finally, the elasto-dynamic deformation of the whole system is obtained using mode superposition method for the case of constant input speed. The effect of geometric stiffness on the mechamism is included in the program with the axial forces of links obtained through the quasi-static displacement analysis. It is found that the geometric stiffness exerts an important effect upon the elasto-dynamic behavior of the flexible linkage mechanism. Elastic deformation of bearing lowers the natural frequencies of the system, resulting smaller elastic displacement at the mid-point of the links and bigger elestic displacement at the ends of the links than rigid bearing. The above investigation of flexible linkage mechanism shows that the effects of the elastic deformation of bearing on the mechanism should be considered to design the mechanism which satisfies more preciously the purpose and the condition of design.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.5
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• pp.1146-1153
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• 2005

This study was investigated so that reliability of disease mechanism diagnosis would be examined, the estimation about disease mechanism item of Questionnaires and the relations of disease mechanism would be inquired about 'health diagnosis program' Questionnaires which were used for the object diagnosis of Oriental medicine in the department of Oriental OB&GY, Oriental Medical hospital of Dong-Eui University. We analyzed the results of Questionnaires for 3354 outpatients who had OB & GY disease in the Oriental Medical hospital of Dong-Eui University from April 2000 to March 2004. The diagnosis Questionnaires(after DSOM (r) S.1.1) was the figures 188, the health diagnosis Questionnaires (after DSOM (r) S.1.1) was the figures 137. phiegm deficiency of qi was used in DSOM (r) R.1.1 as it is. The reliability of DSOM (r) S.1.1 was usually higher than DSOM (r) R.1.1 in deficiency of qi blood stasis insufficiency of Yang heat syndrom damp, 5 case disease mechanism. The reliability of DSOM (r) S.1.1 was usually lower than DSOM (r) R.1.1 in blood deficiency stagnation of qi coldness damp dryness liver heart spleen kidney, 8 case disease mechanism. but the great difference wasn't seen, therefore both DSOM (r) S.1.1 and DSOM (r) R.1.1 had similar result. A meeting point both DSOM (r) S.1.1 and DSOM (r) R.1.1 was above 90% in liver spleen blood stasis blood deficiency, 4 case disease mechanism with the exception of phlegm deficiency of Yim nothing of fluctuations of question. A meeting point of coldness that was 82.47% was lowest, A meeting point of the rest disease mechanism was above 85%. The effect that contributed in producing disease mechanism result and in which pure question was over relevance calculation 0.9, insufficiency of Yang damp phlegm that contributed in producing disease mechanism result was lower comparatively in DSOM (r) R.1.1. But the effect that contributed in producing disease mechanism result and in which pure question was over relevance calculation 0.9 except spleen kidney phlegm in DSOM (r) S.1.1

• Journal of the Korean Society of Combustion
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• v.9 no.4
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• pp.28-34
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• 2004

Numerical simulations of freely propagating flames burning $H_2/HCl/Air$ Air mixtures were performed at atmospheric pressure in order to understand the effect of hydrogen chloride on flame structures. The chemical and physical effects of hydrogen chloride on flame structures were observed. A chemical kinetic mechanism was developed, which involved 26 gas-phase species and 198 forward elementary reactions. Under several equivalence ratios the flame speeds were calculated and compared with those obtained from the experiments, the results of which were in good agreement. As hydrogen chloride as additive was added into $H_2/Air$ flame, the flame speed, radical concentration and NO production rate were decreased. The chemical effect of hydrogen chloride caused the reduction of radical concentration, and then the decrease of the net rate of NO production. It was found that the influence in the reduction of $EI_{NO}$ with the addition of hydrogen chloride was attributed more due to the chemical effect than the physical effect.

• Journal of Korean Elementary Science Education
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• v.34 no.1
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• pp.15-31
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• 2015

The purpose of this study was to investigate elementary student teachers' conceptions about the mechanism of the greenhouse effect, the greenhouse gases, the global warming, and their learning experiences of the greenhouse effect and the global warming. Participants were 82 student teachers in their second year of studies (science education: n=28, not science education: n=27) and in their fourth year of studies (science education: n=27). The open-ended questionnaire was used to examine the teachers' spontaneous ideas depicted by their drawings and/or writings. The results of this study are as follows: First, the student teachers' scientific response rate about key concepts related to the mechanism of the greenhouse effect was low (6.1%~28.0%); Second, although there are various greenhouse gases, it was only carbon dioxide that the student teacher's response rate was more than 80%; Third, only 17.1% of the student teachers clearly distinguished the greenhouse effect and the global warming; Fourth, there was a tendency that the student teacher group in the fourth year of studies and science education showed higher scientific response rate about the concepts than the other two groups.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.166-173
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• 2007

A numerical study was conducted to have the effect of $CO_2$ addition to fuel on the chemical reaction mechanism with the change of the initial concentration of $CO_2$ and the axial velocity gradient. From this study, it was found that there were two serious effects of $CO_2$ addition on a non-premixed flame ; a diluent effect by the reactive species reduction and chemical effect of the breakdown of $CO_2$ by the third-body collision and thermal dissociation. Especially, the chemical effect was serious at the lower velocity gradient of the axial flow. It was certain that the mole fraction profile of $CO_2$ was deflected and CO was increased with the initial concentration of $CO_2$. It was also ascertained that the breakdown of $CO_2$ would cause the increasing of CO mole fraction at the reaction region. It was also found that the addition of $CO_2$ did not alter the basic skeleton of $H_2-O_2$ reaction mechanism, but contributed to the formation and destruction of hydrocarbon products such as HCO. The conversion of CO was also suppressed and $CO_2$ played a role of a dilution in the reaction zone at the higher axial velocity gradient.

• Geomechanics and Engineering
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• v.31 no.1
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• pp.71-86
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• 2022

In Taiwan, an efficient approach for enhancing the stability of colluvium slopes is the drilled shaft method. For slopes with drilled shafts, the soil arching effect is one of the primary factors influencing slope stability and intertwines to the failure mechanism of the pile-soil system. In this study, the contribution of soil arching effect to slope stability is evaluated using the FEM software (Plaxis 3D) with the built-in strength reduction technique. The result indicates the depth of the failure surface is influenced by the S/D ratio (the distance to the diameter of piles), which can reflect the contribution of the soil arching effect to soil stability. When α (rock inclination angles)=β (slope angles) is considered and the S/D ratio=4, the failure surface of the slope is not significantly influenced by the piles. Overall, the soil arching effect is more significant on α=β, especially for the steep slopes. Additionally, the soil arching effect has been included in the proposed stability charts. The proposed charts were validated through two case studies, including that of the well-known Woo-Wan-Chai field in Taiwan. The differences in safety factor (FoS) values between the referenced literature and this study was approximately 4.9%.

• Magazine of the Korea Concrete Institute
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• v.6 no.5
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• pp.193-202
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• 1994

In this study, an equation for modelling the shear strength of reinforced concrete member with web reinforcement is proposed. Although the general formulas for shear strength of reinforced concrete member with small a /d are obtained based on the experimental results, the proposed equation herein is derived from lower bound theorem of limit analysis. The proposed model takes into account arch mechanism and truss mechanism. And ir provides the values of divided shear strength ratio of each mechanism as well as visual understanding of the mechanism on how the given load is transfered to the support. Also, the model takes into account the effect of a /d. longitudinal reinforcement ratio, and web reiriforcement ratio quantitively. Based on the comparisons of the result of this model with previous, test results, it shows good agreements.

• ETRI Journal
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• v.25 no.5
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• pp.356-368
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• 2003

This paper analyzes the characteristics of packet losses in mobile computing environments based on the Gilbert model and then describes a mechanism that can recover the lost audio packets using redundant data. Using information periodically reported by a receiver, the sender dynamically adjusts the amount and offset values of redundant data with the constraint of minimizing the bandwidth consumption of wireless links. Since mobile computing environments can be often characterized by frequent and consecutive packet losses, loss recovery mechanism need to deal efficiently with both random and consecutive packet losses. To achieve this, the suggested mechanism uses relatively large, discontinuous exponential offset values. That gives the same effect as using both the sequential and interleaving redundant information. To verify the effectiveness of the mechanism, we extended and implemented RTP/RTCP and applications. The experimental results show that our mechanism, with an exponential offset, achieves a remarkably low complete packet loss rate and adapts dynamically to the fluctuation of the packet loss pattern in mobile computing environments.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.216-222
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• 2013

This paper deals with the issue of kinematic modeling and analysis of a toggle mechanism. Based on the mathematic model of a conventional five-point type toggle mechanism. New five-point type toggle mechanism has been analyzed by computer simulation method. A sensitivity ratio has been defined and analyzed to compare its performance with four-point type toggle mechanism. A cycloidal motion has been applied to the cross head as an input and the motion of the moving platen is considered as an output. The effect of link design parameter as well as the type of toggle has been investigated by computer simulation to be available for industrial applications of injection molding machines.

• Journal of Communications and Networks
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• v.18 no.6
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• pp.948-961
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• 2016

Internet protocol (IP) spoofing is a serious problem on the Internet. It is an attractive technique for adversaries who wish to amplify their network attacks and retain anonymity. Many approaches have been proposed to prevent IP spoofing attacks; however, they do not address a significant deployment issue, i.e., filtering inefficiency caused by a lack of deployment incentives for adopters. To defeat attacks effectively, one mechanism must be widely deployed on the network; however, the majority of the anti-spoofing mechanisms are unsuitable to solve the deployment issue by themselves. Each mechanism can work separately; however, their defensive power is considerably weak when insufficiently deployed. If we coordinate partially deployed mechanisms such that they work together, they demonstrate considerably superior performance by creating a synergy effect that overcomes their limited deployment. Therefore, we propose a universal anti-spoofing (UAS) mechanism that incorporates existing mechanisms to thwart IP spoofing attacks. In the proposed mechanism, intermediate routers utilize any existing anti-spoofing mechanism that can ascertain if a packet is spoofed and records this decision in the packet header. The edge routers of a victim network can estimate the forgery of a packet based on this information sent by the upstream routers. The results of experiments conducted with real Internet topologies indicate that UAS reduces false alarms up to 84.5% compared to the case where each mechanism operates individually.