• Journal of the Korean institute of surface engineering
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• v.56 no.1
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• pp.12-39
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• 2023

Diseases caused by air pollution and abnormal climate are occurring worldwide due to global warming. Accordingly, the international community has established a strategy to respond to climate change, and major countries have shifted their economic policies to eco-friendly industries. In this study, we investigate the current status of the renewable energy industry and that of responses to carbon neutrality and PM2.5 (air pollution) in the three major Northeast Asian countries of Japan, Korea, and China, covering changes in the corporate perceptions of Environment, Social, Governance and RE100. In more detail, the three major Northeast Asian countries, referred to as the climate villains in the international community, explain the importance of successful entry into the electric vehicles (EV) industry for a rapid transition to an eco-friendly industry. Moreover, we study the application of lightweight materials for vehicles to improve mileage in the EV industry and technical problems to be solved in the future.

• The Korean Journal of Franchise Management
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• v.14 no.3
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• pp.17-35
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• 2023

Purpose: As more and more food franchise companies want to expand overseas, related research is becoming more and more necessary. This study aims to examine the critical factors for successful overseas expansion according to the stages of overseas expansion, derive vital associations, and examine the success factors of overseas expansion through semantic network analysis. Research Design, Data, and Methodology: This study conducted in-depth interviews with three food franchise companies that have experienced overseas expansion and conducted semantic network analysis among crucial associations. The semantic network analysis was conducted using the Textom program. Results: Based on the results of the in-depth interview analysis, the factors considered when expanding overseas were categorized as 1) standardization and localization strategies of overseas franchisees, 2) physical environment of overseas franchisees, 3) entry types of overseas franchisees, 4) constraints of overseas franchisees, and 5) success criteria of overseas franchisees. The semantic network analysis based on the corresponding keywords showed that the importance of local partners is very high in common. Conclusion: This study examined and re-categorized the important factors to consider when a restaurant franchise company expands overseas in a step-by-step manner. In addition, an attempt was made to examine the keywords derived from the semantic network analysis objectively. The results provided theoretical and practical implications for the successful overseas expansion of franchise companies.

• Advances in aircraft and spacecraft science
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• v.11 no.2
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• pp.177-194
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• 2024

The objective of this paper is to compute entire flow field over Apollo-II, Aerospace Reentry Demonstrator (ARD), Orbital Experiment (OREX) with sharp shoulder and rounded shape shoulder and Space Recovery Experiment (SRE) at different flare-cone half-angle of 20° and 35°. This paper addresses numerical solutions of the compressible three-dimensional Euler equations on hexahedral meshes for a freestream Mach 6 and at an angle of incidence 5°. Furthermore, spatial discretization is accomplished by a cell centred finite volume formulation solution and advanced in time by an explicit multi-stage Runge-Kutta method. The flow field characteristics, distribution of surface pressure coefficient and Mach number on fore-body and aft-body are presented as a function of the geometrical parameters of many reentry capsules. The surface pressure variation is numerically integrated to obtain the aerodynamic drag and compared well with impact theory. The present numerical study has observed the significant dependence of the blunt body and the aft-body geometry of the vehicle and can be used to study atmospheric conditions during re-entry trajectory. The numerical analysis reveals the significant influence of capsule geometry on the flow characteristics of the mechanism of upstream and structure of the flow near the wake region and aerodynamic drag coefficient.

• Korean Circulation Journal
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• v.52 no.4
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• pp.251-264
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• 2022

Heart failure with preserved ejection fraction (HFpEF) accounts for approximately half of all heart failure (HF) cases. The prevalence of HFpEF is increasing due to an aging population with hypertension, diabetes mellitus, and obesity. HFpEF remains a challenging clinical entity due to a lack of effective treatment options. Traditional HF medications have not been shown to reduce mortality of patients with HFpEF, and an implantable cardioverter-defibrillator is not indicated due to normal ejection fraction. Sudden death is the most common mode of death in patients with HFpEF; however, the underlying mechanisms of sudden death are not fully elucidated. Although ventricular arrhythmias are responsible for the majority of sudden deaths in general, their contribution to sudden deaths in HFpEF patients is likely less significant. The mechanisms of ventricular arrhythmias in HFpEF are 1) reduced conduction velocity due to ventricular hypertrophy, 2) delayed repolarization due to potassium current down-regulation, 3) calcium leakage due to altered excitation-contraction coupling, and 4) increased ventricular fibrosis caused by systemic inflammation. Hypertension and subsequent ventricular hypertrophy reduce the conduction velocity in HFpEF hearts via heterogeneous distribution of connexin 43. Delayed repolarization caused by potassium current down-regulation in HFpEF hearts provides a window for early afterdepolarization to trigger ventricular arrhythmias. Altered excitation-contraction coupling in HFpEF can cause calcium to leak and trigger delayed afterdepolarization. Increased systemic inflammation and subsequent ventricular fibrosis provide substrates for re-entry. Further research is warranted to investigate the detailed mechanisms of ventricular arrhythmias in HFpEF.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.2
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• pp.219-230
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• 2023

Cities are continued to be highly advanced and metropolitanized. Lands adjacent to road make entry/exit connection increase along with construction of facilities for various purposes. However, in the absence of specific installation standards of entry and exit connection, inappropriate access location, types of access, and operation methods are deteriorating the level of traffic services at existing roads and intersections. Therefore, in order to minimize the traffic impact from entrances connected to minor arterial roads and colletor roads, first, this study re-established the waiting length in the intersection of upstream and downstream and length required for changing lanes and between entrance/exit and connection, considering the road and traffic environment in contact with the entrance. Second, it is suggested that the operation method depending on the connection type and whether to install left turn lane and acceleration and deceleration lane can be determined quantitatively by relation with the service level of nearby intersection after calculating the threshold amount of business site through negative social cost, which is the difference between the installation cost of the left turn lane and the acceleration and deceleration lane according to the type of access to the entrance and exit.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.1191-1204
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• 2012

As attackers try to paralyze information security systems, many researchers have investigated security testing to analyze vulnerabilities of information security products. Penetration testing, a critical step in the development of any secure product, is the practice of testing a computer systems to find vulnerabilities that an attacker could exploit. Security testing like penetration testing includes gathering information about the target before the test, identifying possible entry points, attempting to break in and reporting back the findings. Therefore, to obtain maximum generality, re-usability and efficiency is very useful for efficient security testing and vulnerability hunting activities. In this paper, we propose a threat analysis based software security testing technique for evaluating that the security functionality of target products provides the properties of self-protection and non-bypassability in order to respond to attacks to incapacitate or bypass the security features of the target products. We conduct a security threat analysis to identify vulnerabilities and establish a testing strategy according to software modules and security features/functions of the target products after threat analysis to improve re-usability and efficiency of software security testing. The proposed technique consists of threat analysis and classification, selection of right strategy for security testing, and security testing. We demonstrate our technique can systematically evaluate the strength of security systems by analyzing case studies and performing security tests.

• Journal of Periodontal and Implant Science
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• v.45 no.6
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• pp.229-237
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• 2015

Purpose: The aim of this study was to determine the clinical feasibility of using dehydrothermally cross-linked collagen membrane (DCM) for bone regeneration around peri-implant dehiscence defects, and compare it with non-cross-linked native collagen membrane (NCM). Methods: Dehiscence defects were investigated in twenty-eight patients. Defect width and height were measured by periodontal probe immediately following implant placement (baseline) and 16 weeks afterward. Membrane manipulation and maintenance were clinically assessed by means of the visual analogue scale score at baseline. Changes in horizontal thickness at 1 mm, 2 mm, and 3 mm below the top of the implant platform and the average bone density were assessed by cone-beam computed tomography at 16 weeks. Degradation of membrane was histologically observed in the soft tissue around the implant prior to re-entry surgery. Results: Five defect sites (two sites in the NCM group and three sites in the DCM group) showed soft-tissue dehiscence defects and membrane exposure during the early healing period, but there were no symptoms or signs of severe complications during the experimental postoperative period. Significant clinical and radiological improvements were found in all parameters with both types of collagen membrane. Partially resorbed membrane leaflets were only observed histologically in the DCM group. Conclusions: These findings suggest that, compared with NCM, DCM has a similar clinical expediency and possesses more stable maintenance properties. Therefore, it could be used effectively in guided bone regeneration around dehiscence-type defects.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.184-192
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• 2014

In this paper, the lifetime of the artificial space objects in the LEO is analysed by using TLE data, which is provided by JSpOC. We observed the change of the number of space objects from 1957 and determined the reason of space debris generation. And then, we performed the analysis about present condition of space debris environment. The lifetime analysis includes a total of 11,792 artificial space objects and performed until the year 2050 by orbit propagation. We analyze the annual reentry frequency for the high RCS objects such as nonoperational satellites and rocket bodies, which have the possibility of earth ground impact through STK/Lifetime Tool for accurate and effective calculation. The results show that 9 payloads or rocket bodies will be decayed annually and 2 or 3 objects of total value have the possibility of ground impact. In addition, it is also shown that the 40% of a total analysed objects have the lifetime over 200 years.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1048-1053
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• 2015

Ablative materials in a thermal protection system for atmospheric re-entry suffers from the most severe heat fluxes and temperatures, which induces surface recession in the thickness direction. In this paper, a 0.4MW arc-heated wind tunnel is operated to test for ablative materials, and a non-contact three-dimensional surface measuring system is used to evaluate the different surface characteristics of them. In particular, by postprocessing the three-dimensional image data, the surface roughness and recession of ablative materials can be calculated before and after the wind tunnel test. Moreover, the surface properties are analyzed quantitatively by comparing volume and mass losses of the test specimens.

• Korean journal of communication and information
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• v.78
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• pp.79-115
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• 2016

This study, by proposing a case study of community radio, attempts to expand the horizon of academic and social discussion on the medium that has been disproportionately skewed towards discourses on alternative media, technology, and programming content. As residents of local community actively participate in the production process, they reconstruct their cultural identities. In that sense, community radio is a medium that makes it possible the re-negotiation and reconfiguration of cultural identities of local residents. That is to say, a case study on the specific ways in which community residents appropriate community radio in reconstructing their identities offers us some entry points where we may come up with a new perspective on the identity of community radio. The results of fieldwork show that community radio, as it is closely intertwined with the residents' participatory cultural practices, is a medium of 'lived culture' -i.e., a medium that contributes to the making of civility, communitarianism, and social network. Community radio, then, may be redefined as an interactive medium that contributes to the formation of social rapport and solidarity.