• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2301-2306
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• 2008

SIP(Session Initiation Protocol) has become an universal standard for multimedia communications for both wired and wireless networks since it has been adopted as a standard protocol for IMS platform in 3GPP standardization organization at November 2000. In this paper, we design and implement a SIP-based softphone client program which provides telephony service between internet users and a call center equipped with VoIP gateway. A softphone client based on PC-to-phone connection should guarantee to provide interoperability with various VoIP gateways and higher portability to be able to operate on different PC environments. The softphone client program in this paper has been developed with SIP 2.0 standard protocol to support interoperability and with JAIN SIP and JMF package to achieve higher portability.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.6
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• pp.595-602
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• 2009

Great number of ships has been built by Korean Shipyards since early of 2,000 due to the expanding worldwide trade. Most of shipyards have enlarged the weight of erection block and many blocks have been assembled in block fabrication factories outside the shipyards to reduce the shipbuilding period. Especially, Giga blocks that exceed 2,000 tons are often assembled by the block fabrication factories outside the shipyard. Generally, the blocks are transported to building dock in shipyard by towing barges. Accident can be occurred during the sea transportation and it may bring about not only the delay of delivery but also a disaster on the ocean environments. Transportation condition of GPE (Grand Pre-Erection) block differs from the ocean going conditions of marine vessels. Special consideration should be included before transportation work in order to guarantee the safety of GPE blocks and barge carriers. In this paper, several examples, which have been investigated to set up the safety standard of transportation of the GPE blocks on coastal routes, are introduced. For the barge transportation on coastal sea route, the design criteria are discussed, considering the design wave, the acceleration induced by wave, structural strength, and the fixture condition of blocks.

• Advances in aircraft and spacecraft science
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• v.4 no.2
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• pp.145-167
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• 2017

The presented paper gives an overview of several projects addressing the experimental characterization and control of the buffet phenomenon on 3D turbulent wings in transonic flow conditions. This aerodynamic instability induces strong wall pressure fluctuations and therefore limits flight domain. Consequently, to enlarge the latter but also to provide more flexibility during the design phase, it is interesting to try to delay the buffet onset. This paper summarizes the main investigations leading to the achievement of open and closed-loop buffet control and its experimental demonstration. Several wind tunnel tests campaigns, performed on a 3D half wing/fuselage body, enabled to characterize the buffet aerodynamic instability and to study the efficiency of innovative fluidic control devices designed and manufactured by ONERA. The analysis of the open-loop databases demonstrated the effects on the usual buffet characteristics, especially on the shock location and the separation areas on the wing suction side. Using these results, a closed-loop control methodology based on a quasi-steady approach was defined and several architectures were tested for various parameters such as the input signal, the objective function, the tuning of the feedback gain. All closed-loop methods were implemented on a dSPACE device able to estimate in real time the fluidic actuators command calculated mainly from the unsteady pressure sensors data. The efficiency of delaying the buffet onset or limiting its effects was demonstrated using the quasi-steady closed-loop approach and tested in both research and industrial wind tunnel environments.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.470-478
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• 2019

Because the global positioning system (GPS) is not available in underwater environments, an inertial navigation system (INS)/doppler velocity log (DVL) integrated navigation system is generally implemented. In general, an INS/DVL integrated system adopts a loosely coupled method. However, in this loosely coupled method, although the measurement equation for the filter design is simple, the velocity of the body frame cannot be accurately measured if even one of the DVL transducer signals is not received. In contrast, even if only one or two velocities are measured by the DVL transducers, the tightly coupled method can utilize them as measurements and suppress the error increase of the INS. In this paper, a filter was designed to regenerate the measurements of failed transducers by taking advantage of the tightly coupled method. The regenerated measurements were the normal DVL transducer measurements and the estimated velocity in RPM. In order to effectively estimate the velocity in RPM, a filter was designed considering the effects of the tide. The proposed filter does not switch all of the measurements to RPM if the DVL transducer fails, but only switches information from the failed transducer. In this case, the filter has the advantage of being able to be used as a measurement while continuously estimating the RPM error state. A Monte Carlo simulation was used to determine the performance of the proposed filters, and the scope of the analysis was shown by the standard deviation ($1{\sigma}$, 68%). Finally, the performance of the proposed filter was verified by comparison with the conventional tightly coupled method.

• Smart Media Journal
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• v.8 no.1
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• pp.67-73
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• 2019

This study investigates Active Learning and Facilitation Convergence Education Program which can improve core competency to cope with vocational education in the fourth industrial revolution era. I applied the integrated advantages of Active Learning which enhances 'problem solving skill' and those of Facilitation for creative thinking idea to application design process coursework and verified the effectiveness of such education method through student satisfaction survey. I also designed application contents for the students who are familiar with the mobile environments and UI contents for data visualization which can help those students to improve their skills in software. Every coursework was conducted as a team project. As a result, Active Learning and Facilitation Convergence Education Program is found to be helpful in improving the basic skills and competencies required in college education. I hope this work helps to reduce the educational gap between industry and professional colleges.

• Journal of Advanced Navigation Technology
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• v.23 no.1
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• pp.44-54
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• 2019

In many countries, there are needs of new transportations to replace ground congestions due to growing number of cars. In addition, the increase in the number of cars held by economic growth will further increase traffic congestion in the future. To overcome this problem, many researches have been performed for personal air vehicle (PAV). In this study, the wing loading and the power-to-weight ratio that are major design parameters for the sizing of roadable PAVs were calculated for different kinds of airfoil and engine types. I.e., in the sizing process, the study was conducted to determine the design point using the graphs of wing loading, power-to-weight ratio, brake horse power, and fuel efficiency for the given mission profiles considering domestic environments and the FAR PART 23 which is the GA class aircraft certification standard. As a result of sizing, using diesel engine require high maximum take-off weight, wing area, and power compared to gasoline engine due to more engine weight.

• Journal of Engineering Education Research
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• v.24 no.2
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• pp.20-28
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• 2021

In 2020, the COVID-19 pandemic has brought dramatic changes in the field of engineering education. Contrary to the traditional engineering education emphasis on content-oriented, design-based, hands-on, experimental, and field experience, most of engineering classes in 2020 had to be undertaken remotely online. However, it has not been explored how professors and students perceive about such a shift in engineering education. The aim of the current study was to investigate the perceptions of professors and students on online classes in engineering colleges during spring Semester 2020. Questionnaire data were collected from 100 professors and 4,152 students in the college of engineering. The results of this study were as following: Students were less satisfied with the online classes than professors. The online lecture method that students were most satisfied with was the recorded lecture. This is likely due to the fact that the recorded lectures can be repeated multiple times anytime, anywhere. Moreover, the experimental classes, which conventionally has more of an emphasis on the hands-on experience, also had to be conducted remotely, showing even lower satisfaction among students. Most of professors reported that the average hours they spent on preparing for online lecture increased compared to face-to-face class. Both professors and students preferred in-person exam as a desirable method of end-of-semester assessment for grading. The results of the current study have important implications for the improvement of online course environments. It is important for professors to design a structured class suitable for online education and understand the challenges students encounter during online classes. Also, professors should communicate more openly about their expectations and rubrics for class goals and assignments. Schools also needs to make effort to provide the support for the internet environment of students.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.5
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• pp.21-28
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• 2018

This study analyzed the physical characteristics and change characteristics of urban detached residential area. In the reality of South Korea in which the history of modern urbanization is not long, the densification that progressed together with sudden population growth without any consideration of city plans became to reveal many problems. Thereafter, apartment-centered large scaled development plans have been implemented until now as an alternative for the foregoing. As the residential environments of old downtown areas that were excluded from the development have been gradually deteriorated, large scaled re-development and reconstruction projects have been adopted as ways to solve the problems of the old downtown areas. On one hand, the development methods that damage the history of the detached housing areas have been resisted. With such a background, this study attempted the analysis of the change characteristics of the Kookmin Housing Complex in Suyu 1-dong, Seoul with a view to playing the role of evidentiary materials for the disappearing urban detached housing areas or those urban detached housing areas that may be revived. This author hopes and the results of this study will lead to careful development that presents measures to maintain and develop modern urban residential areas where the history of past residential areas and culture are disappearing due to full-scale redevelopment.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.8
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• pp.105-116
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• 2018

The architecture reflects geographical characteristics such as geographical environments and climate, it has the characteristics and cultural characteristics of the region that has been constructed. Hansen Village constructed in Period of Japanese Occupation at 'Sorok-Island' in Go-heung, Jeollanam-do was also based on this point. The village, which is a ward of Sorok-Island Province, consists of a village in which patients are self-sufficient in economic and social activities, unlike the modern hospital systems where patients and treatments are concentrated in a single room. Additionally, the facilities for patient acceptance were gradually expanded, with limited interaction with external. Sorok-island shows the expansion of the village center where the new village is formed with the increase of the number of the early adopters in the 1910s and the accommodation facility is built, and it gradually increases the necessary space by opening and repairing the existing facilities by the 1990s Change. In addition, the spatial composition of the village can be divided into three types : decentralized, centralized and single-shift ; it has the same causal relationship as the village's formation. The purpose of this study is identifying the uniqueness of Sorok-Island by analyzing the correlation between the formation of a village to accommodate Hansen Patients in Sorok-Island and the spatial Component Factor.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.11
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• pp.75-84
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• 2018

This study analyzed users' acceptance and intention to use in addition to needs and preferences of smart home technologies, and identified the differences in technology preference and acceptance by different factors. The subjects were residents in the 40s and 60s residing in the Seoul or suburbs of Seoul, and questionnaires were conducted in the 40s while interviews with questionnaires were conducted in the 60s. A total of 105 questionnaires were used as data, and frequency, mean, crossover, independent sample t test, one-way ANOVA and multiple regression analysis were performaed using SPSS23. The results of this study are as follows. First, hypertension, hyperlipidemia and hypercholesterolemia were the most common diseases among respondents and if there was no discomfort, they would like to continue living in the homes of the current residence. Therefore, the direction of smart home development should support the daily living and health care so that residents can live a healthy life for a long time in their living space. Second, the technologies that residents most need were a control technology of residential environments and a monitoring technology of residents' health and physiological changes. The most preferred sensor types are motion sensors and speech recognition while video cameras have a very low preference. Third, technology anxiety was the most significant factor influencing intention to accept smart home technology. The greater the technology anxiety is, the weaker the acceptance of technology. Fourth, when applying smart residential technology in homes, various resident characteristics should be considered. Age and technology intimacy were the most influential variables, and accordingly there were differences in technology preference and acceptance. Therefore, a user-friendly smart home plan should be done in the consideration of the results.