• Journal of Convergence Society for SMB
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• v.2 no.2
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• pp.35-41
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• 2012

The rapid development of cloud computing and mobile internet service changes to an mobile cloud service environment that can serve and pay computing source that users want anywhere and anytime. But when user misses mobile device, the respond to any threat like user's personal information exposal is insufficient. This paper proposes cloud service access control model to provide secure service for mobile cloud users to other level users. The proposed role-based model performs access authority when performs user certification to adapt various access security policy. Also, the proposed model uses user's attribute information and processes before user certification therefore it lowers communication overhead and service delay. As a result, packet certification delay time is increased 3.7% and throughput of certification server is increased 10.5%.

• Korean Journal of Construction Engineering and Management
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• v.13 no.1
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• pp.148-159
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• 2012

Recently construction companies' capital condition has been aggravated due to low profit, fierce competition and market contraction. For this reason, the companies rely on public construction projects that protect construction fee by regulations. Despite these regulations, problems regarding progress payment are constantly happening. Also, insufficient analysis on interaction between contractors makes policy making difficult. Thus, in this study, interaction between contractors are quantitatively determined according to delay of application and payment based on current public construction regulations on construction stage. A system dynamics model is used, which analyzes the problems based on an interaction between contractors, and solutions for progress payment application and payment delay are suggested according to the research results.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.4
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• pp.285-292
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• 2021

Osmotic power is to produce electric power by using the chemical potential of two flows with the difference of salinity. Water permeates through a semipermeable membrane from a low concentration feed solution to a high concentration draw solution due to osmotic pressure. In a pressure retarded osmosis (PRO) process, river water and wastewater are commonly used as low salinity feed solution, whereas seawater and brine from the SWRO plant are employed as draw solution. During the PRO process using wastewater effluent as feed solution, PRO membrane fouling is usually caused by the convective or diffusive transport of PRO which is the most critical step of PRO membrane in order to prevent membrane fouling. The main objective of this study is to assess the PRO membrane fouling reduction by pretreatment to remove organic matter using coagulation-UF membrane process. The experimental results obtained from the pretreatment test showed that the optimum ferric chloride and PAC dosage for removal of organic matter applied for the coagulation and adsorption process was 50 mg/L as FeCl₃ (optimum pH 5.5). Coagulation-UF pretreatment process was higher removal efficiency of organic matter, as also resulting in the substantial improvement of water flux of PRO membrane.

• Journal of Digital Convergence
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• v.20 no.2
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• pp.431-446
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• 2022

This study tested the possibility of applying the integrated social cognitive career theory for workers with disabilities to explore ways of predicting and enhancing their subjective well-being. It analyzed 952 adults who were employed for three years, among the workers who had participated in the Panel Survey of Employment for the Disabled from 2016 to 2018. The results showed that disability acceptance was positively related to occupational self-efficacy, job satisfaction, and life satisfaction with statistical significance, and that occupational self-efficacy had a partial mediating effect on the relationship between job satisfaction and disability acceptance. Moreover, both auto-regressive and cross-lagged effects between disability acceptance and job satisfaction were found to be statistically significant. These findings imply that disability acceptance and occupational self-efficacy can be regarded as important factors to increase the subjective well-being of workers with disabilities.

• The Journal of the Korea Contents Association
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• v.22 no.9
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• pp.473-484
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• 2022

This study aimed to verify the reciprocal casual relationship between self-rated health status and depression in the elderly through longitudinal analysis. An autoregressive cross-lagged model was identified. This study analyzed 3,363 elderly people aged 65 or older using the 5th, 6th, and 7th wave data from Korean Longitudinal Study of Ageing(KLoSA). The results are as follows. First, self-rated health status had a positive(+) autoregressive effect. Second, depression had a positive(+) autoregressive effect. Third, self-rated health status had a negative(-) cross-lagged effect on depression, but depression was not a casual predictor of self-rated health status. Based on these findings, it was suggested that there is a need for systematic policies to improve basic fitness in the early stages of old age, as well as the need to expand health promotion programs and implement integrated depression management programs.

• Journal of Digital Convergence
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• v.16 no.2
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• pp.431-440
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• 2018

This study examined the effectiveness of the cognitive activity integration program to delay the progression of the mild demented elderly. The subjects were divided into experimental group and comparative group for 12 cases of mild dementia, and the cognitive activity integration program was conducted for 8 weeks and compared with the MMSE-K, ADL & IADL, CDR and GDS scales. The results show that the effectiveness and continuity of the program are as follows. First, as an implication of practical dimension, integrated program of fusion and complexity is more effective than cognitive activity program of single domain. Second, the cognitive activity integration program must be continuously provided to maintain its effectiveness. Third, the cognitive activity integration program is as important as the practice process. It is necessary to develop and disseminate a cognitive activity integration program that reflects fusion and complex treatment techniques applicable to the elderly with mild dementia by practical suggestion. Policy suggestions are needed to continue the ongoing cognitive activity integration program, to maintain effectiveness, and to delay the progress of dementia.

• The KIPS Transactions:PartA
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• v.15A no.1
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• pp.53-60
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• 2008

Streaming media has contributed to a significant amount of today's Internet Traffic. Like traditional web objects, rich media objects can benefit from proxy caching, but caching streaming media is more of challenging than caching simple web objects, because the streaming media have features such as huge size and high bandwidth. And to support various bandwidth requirements for the heterogeneous ubiquitous devices, a transcoding proxy is usually necessary to provide not only adapting multimedia streams to the client by transcoding, but also caching them for later use. The traditional proxy considers only a single version of the objects, whether they are to be cached or not. However the transcoding proxy has to evaluate the aggregate effect from caching multiple versions of the same object to determine an optimal set of cache objects. And recent researches about multimedia caching frequently store initial parts of videos on the proxy to reduce playback latency and archive better performance. Also lots of researches manage the contents with segments for efficient storage management. In this paper, we define the 9-events of transcoding proxy using 4-atomic events. According to these events, the transcoding proxy can define the next actions. Then, we also propose the segment-based caching policy for the transcoding proxy system. The performance results show that the proposing policy have a low delayed start time, high byte-hit ratio and less transcoding data.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.356-362
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• 2022

Research related to hydrogen technology is being actively conducted around the world. Korea is also making great efforts to develop technology to leap forward as a hydrogen economy powerhouse. In particular, the world's No. 1 hydrogen vehicle penetration rate is proof of this. However, the construction of hydrogen refueling stations is being delayed. The biggest delay factor is the public opposition. As such, policies without public support cannot be successfully implemented and are not sustainable. Therefore, this study intends to analyze the factors affecting the acceptability of hydrogen refueling stations in favor of and against them. As a research method, the basic factors affecting acceptability were identified by reviewing previous studies, and a questionnaire was designed and investigated based on the established factors. The validity and reliability of the questionnaire were verified, and the hypothesis was verified through correlation analysis. And, using structural equation modeling, a factor model was developed on the acceptability of hydrogen refueling stations. As a result of the study, acceptability defined private acceptability and public acceptability. In the case of private acceptability, it was confirmed that the higher the attitude toward the environment, the higher the level of knowledge about the hydrogen charging station, and the lower the degree of feeling the risk of the hydrogen charging station, the higher the acceptability. In the case of public acceptability, it was confirmed that the higher the benefit, the better the attitude toward the environment, and the lower the risk-taking characteristics of the individual, the higher the acceptability. Therefore, in this study, based on the potential factors verified in previous studies, the main factors affecting the acceptance on hydrogen refueling stations were identified. And the acceptance model was developed using structural equation modeling. This study is expected to provide basic data to seek ways to improve the acceptance of public when implementing national policies such as hydrogen refueling stations, and to be used analysis data for scientific communication.

• Korean Journal of Social Welfare Studies
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• v.42 no.3
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• pp.183-206
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• 2011

This study examined the longitudinal relationship between academic achievement and school satisfaction using a data of the Seoul Panel Study of Children(SPSC). Fully autoregressive cross-lagged analysis and multi-group comparison were performed to measure the longitudinal relationship between two constructs as well as differences between poverty and non-poverty groups. The results showed that both academic achievement and school satisfaction were stable over time in non-poverty group. Academic achievement at the 4th grade significantly affected the school satisfaction at the 6th grade and it subsequently affected on the academic achievement at the 8th grade in non-poverty group. In contrast, academic achievement was not consistent over time in poverty group. Only the school satisfaction at the 6th grade affected the academic achievement at the 8th grade. The findings of this study have various practical implication for school interventions. It is more important to keep supporting the children to maintain the level of academic achievement in non-poverty group. While, in poverty group, it is essential to make school satisfaction and academic motivation increase with school attachment programs.

• The Korean Journal of Air & Space Law and Policy
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• v.33 no.2
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• pp.267-290
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• 2018

This paper reviews and criticizes the EU Case of C-452/13, Germanwings GmbH v. Ronny Henning. Under this case, Ronny Henning later sued Lufthansa's budget carrier Germanwings after it refused to pay him 250 euros compensation for a delay he said totalled more than three hours. Germanwings, however, maintained his flight had arrived only two hours and 58 minutes behind schedule. In those circumstances, the following question to the European Court of Justice (ECJ) for a preliminary ruling: What time is relevant for the term time of arrival used in Articles 2, 5 and 7 of Regulation [No 261/2004]: (a) the time that the aircraft lands on the runway (touchdown); (b) the time that the aircraft reaches its parking position and the parking brakes are engaged or the chocks have been applied (in-block time); (c) the time that the aircraft door is opened; (d) a time defined by the parties in the context of party autonomy? ECJ says that the situation of passengers on a flight does not change substantially when their aircraft touches down on the runway at the destination airport, when that aircraft reaches its parking position and the parking brakes are engaged or when the chocks are applied, as the passengers continue to be subject, in the enclosed space in which they are sitting, to various constraints. Therefore, it is only when the passengers are permitted to leave the aircraft and the order is given to that effect to open the doors of the aircraft that the passengers may in principle resume their normal activities without being subject to those constraints. ECJ rules that it is apparent that Articles 2, 5 and 7 of Regulation No 261/2004 must be interpreted as meaning that the concept of 'arrival time', which is used to determine the length of the delay to which passengers on a flight have been subject, corresponds to the time at which at least one of the doors of the aircraft is opened, the assumption being that, at that moment, the passengers are permitted to leave the aircraft.