• Journal of Korea Port Economic Association
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• v.38 no.4
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• pp.187-198
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• 2022

This study attempted to examine whether the spread of infectious diseases and quarantine measures such as border blockade and restrictions on movement due to the global spread of the COVID-19 pandemic is the cause of a decrease in product trade. To this end, a gravity model analysis was conducted using commodity trade statistics from Korea and major trading partners. As a result of the analysis, it was empirically confirmed that in 2020, the time of the spread of COVID-19, the influence of the COVID-19 pandemic was an obstacle to reducing Korea's trade. However, in the case of 2021, it was not possible to confirm whether the impact of the pandemic had a significant effect on commodity trade. As the impact of the COVID-19 pandemic in 2020 and 2021 is different, the commodity trade situation in 2022 when the COVID-19 epidemic is stably managed is also likely to change. Since factors such as response to COVID-19 and the spread of vaccines vary from country to country, it is thought that such various factors should be fully considered in the process of establishing policies to end the COVID-19 era

• The Journal of the Korea Contents Association
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• v.11 no.9
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• pp.17-25
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• 2011

The wireless mesh networks are recently getting much attention for commercial applications. In such networks, the service should be uninterrupted when roaming from one domain to another while the authentication for a secure access should be maintained. The challenge is to consider the authentic coordination between the home domain and foreign domains and the maintenance of local authenticity between foreign domains. In this paper, a novel authentication method is presented so that a mobile mesh node can be effectively authenticated and obtain an secure connection in foreign domains. In the proposed method, the authentication process does not rely on an end-to-end connection between the foreign domain and the home domain. Even without a connectivity to the home domain, the foreign domain can provide an effective authentication of a mesh node by consulting one of the neighboring foreign domains that has been visited by the mobile mesh node. In order to verify the performance of our proposed method, a qualitative analysis has been performed and compared to those of conventional methods. The results show that our method is superior to the conventional ones in terms of authentication response time and authentication service robustness.

• Journal of Drive and Control
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• v.17 no.3
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• pp.47-56
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• 2020

As a shift control of automatic transmission was managed with the electronic control unit (ECU), shift quality which is a measure of shift shock during gear change has markedly improved. However, the initial clutch pressure control of the clutch filling phase should continue to rely on the predetermined control input since the input and output speeds are unchanged until the shifting process attains the inertia phase. It is critical to minimize the clutch response time and control the clutch pressure accurately at the end of clutch fill to achieve quick shift response and smoothness. Advanced transmission companies have adopted an auto calibration method which establishes the databases for the clutch piston fill-up attributes and the frictional characteristics of the disks. In this study, a distinctive auto calibration algorithm for forklift transmission under development is proposed and verified with the real-vehicle test. The experimental calibration results showed consistent turbine dynamics at the initial stage of shifts with the properly calibrated clutch-fill control parameters. By using this technique, it is necessary to finalize the shift control for the various operation conditions.

• The korean journal of orthodontics
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• v.11 no.1
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• pp.7-15
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• 1981

Tooth movement by orthodontic force is based upon alveolar bone resorption at compression site and bone formation at tension site of tooth. The function of cyclic AMP is to participate not only in initial action of bone cells by mechanical forces but also in the continuous cellular response leading to bone remodeling. This experiment was performed to clarify the role of cyclic AMP in bone remodeling by mechanical forces. The orthodontic forces of about 80 gm and 100 gm were applied to the right canines of maxillary and mandibular bone, respectively, in cats, treated for periods of time ranging from one hour to 28 days. Alveolar bones were obtained from compression and tension sites surrounding tipping maxillary and mandibular canines as well as from contralateral control sites. The samples were extracted, boiled and homogenized, and the supernatants were assayed for cyclic AMP by a radioimmunoassay method. The results were as follows: 1. The orthodontic movement of canines was increased to the end of experimental period and the action of orthodontic forces on tooth movement was more effective in maxillary canine. 2. The cyclic AMP levels of alveolar bones in compression and tension sites initially decreased, then increased and remained elevated to the end of experiment. The differences of the cyclic AMP levels between treated sites and non-treated sites were gradually increased. 3. The cyclic AMP levels in treated sites of mandibular alveolar bone was higher than that of maxillary alveolar bone.

• Smart Media Journal
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• v.12 no.7
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• pp.27-42
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• 2023

The development of cloud services and IoT technology has radically changed the cloud environment, and has evolved into a new concept called fog computing and F2C (fog-to-cloud). However, as heterogeneous cloud/fog layers are integrated, problems of access control and security management for end users and edge devices may occur. In this paper, an F2C-based IoT smart health monitoring system architecture was designed to operate a medical information service that can quickly respond to medical emergencies. In addition, a role-based service access control technology was proposed to enhance the security of user's personal health information and sensor information during service interoperability. Through simulation, it was shown that role-based access control is achieved by sharing role registration and user role token issuance information through blockchain. End users can receive services from the device with the fastest response time, and by performing service access control according to roles, direct access to data can be minimized and security for personal information can be enhanced.

• Journal of Korea Trade
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• v.25 no.6
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• pp.105-125
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• 2021

Purpose - This study analyzes the effects that the response to the technical barriers to trade (TBT), which are used by various countries as means to restrict imports, exerts on exports at a time when protectionism is emerging in the face of a global economic downturn. TBT has been widely used in developed countries for the safety and protection of their people. Recently, the use of TBT as a tool of protectionism has increased considerably in developing countries as well. Therefore, this study analyzes the South Korean SMEs' response and export performance. Design/methodology - To analyze SMEs' response to TBT and their export performance, this study conducted empirical analysis through statistical analysis. To this end, the research established a theory based on previous research and designed its hypothesis and research model. To verify the hypothesis and research model, factor analysis addressing validity and reliability was performed using SPSS 25 and AMOS 26, and the structural equation model was analyzed. Findings - This study found the causal relationship between the independent variable, the mediating variable, and the dependent variable adopted against the theoretical background to have little or no effect, in contrast with previous studies. In a break from previous studies, all hypotheses were rejected for innovation strategic competencies, one of the sub-factors of the independent variable, which is believed to be a result of the lack of practical research related to TBT. Originality/value - Previous studies performed analysis using trade statistics or macro data. A number of such studies analyzed the relationship between technical regulation and trade volume. This study differs from previous studies in some respects, because it analyzed the export performance of companies by establishing a hypothesis and implementing a research model with the factors analyzed in previous studies. In addition, a new attempt has been made by classifying the TBT response factors into technology competencies, human resource competencies, and innovation strategic competencies, and utilizing technology innovation and the export support system as mediating effects.

• Membrane Journal
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• v.20 no.3
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• pp.197-202
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• 2010

Polyurethane diagnostic membranes were prepared to measure blood glucose level of diagnostics. Final absorbances at 680 nm through activated polyurethane membranes were measured at various concentration of glucose in blood. The end-point results of varing absorbance values as time (K/S) was found to have a linear relationship toward the blood glucose concentration. The effects of hematocrit on the glucose concentration measurements were examined. In low hematocrit, dose-response slope (DRS) values between gluose concentration and K/S values did not show the big differences compared to those in plasma. However, in high hematocrit (more than 40%) DRS values were considerably decreased.

• Membrane Journal
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• v.21 no.4
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• pp.329-335
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• 2011

A new type of diagnostic membranes based on methoxyethoxy and trifluoroethoxy co-substituted polyphosphazene has been prepared to measure blood glucose level of diabetics. Final absorbances at 680 nm through activated polyphosphazene membranes were measured at various concentration of glucose in plasma or blood. The end-point results of varing absorbance values as time (K/S) was found to have a linear relationship toward the blood glucose concentration. The effects of substitution rates with hydrophilic groups and hydrophobic groups on the measurements of glucose concentration were studied. Dose-response slope (DRS) values between glucose concentration and K/S values increased as the hydrophilic substitution rates increased. However, in more than 30% of the substitution rates, it was difficult to measure exact concentration level of glucose because DRS increased rapidly.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.2
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• pp.132-151
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• 1993

The proposed method in this paper. termed the substructural reanalysis technique, utilizes the computational merits of the component mode synthesis technique and of reanalysis technique for the design sensitivities of the dynamic characteristics of substructurally combined structure. It is shown that the dynamic characteristics of the entire structure can be obtained by synthesizing the substructural eigensolution and the characteristics of the eigensolution for the design variables of the modifiable substructure. In this paper , the characteristics of the eigenvalue problems obtained by this proposed method are compared to exact eigensolution in terms of accuracy and computational efficiency. and the advantage of this proposed method as compared to the direct application of the whole structure and experimental results is demonstrated through examples of numerical calculation for the dynamic characteristics (natural frequencies and mode shapes) of a flexible vibration of thin cylinderical shell with branch shell under 2-end fixed positions, boundary condition. Thin cylinderical shell of overall length 1280mm, external diameter 360mm, thickness 3mm with branch shell is made of mild steel. The load condition for dynamic response in this paper is impulsive load of which magnitude is 10kgf, which have short duration of 0.1 sec. and time interval applied to calculate. $\Delta$T is 1.0$\times$10 super(-4) seconds.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.265-268
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• 2005

This paper deals with the optimal design of a permanent magnet linear synchronous motor (PMLSM) with the analysis of prototype PMLSM. In the PMLSM, thrust ripple is one of the causes disturbing high-precision position control. Therefore, Response surface methodology (RSM), one of the optimization methods, is applied to obtain the shape decreasing thrust ripple of the prototype PMLSM. In the end, characteristic analysis of the PMLSM is performed by space harmonic method for shortening of a computation time, and final results is verified by finite element analysis.