• Journal of dental hygiene science
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• v.15 no.5
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• pp.636-641
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• 2015

The purpose of this study was to examine the oral health recognition and aesthetic interest of flight attendant. The data was collected 314 flight attendant from June to July 2014 in A Airlines. Questionnaires were used to measure the levels of the health & oral health recognition, experience and requirement of oral esthetic therapy. The data was analyzed using descriptive statistics, T-test, ANOVA, Pearson's correlation, structural equating model by the PASW Statistics 18.0 program. According to the research result, oral health awareness were not healthier than general health. Oral health was an important factor to influence the external image. The flight attendant received aesthetic dental care to improve the external image. However, self-assessment results that oral health condition was significantly lower. Therefore they are required oral care practice with aesthetic dental care.

• Journal of Welding and Joining
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• v.15 no.4
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• pp.143-153
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• 1997

In this study, bending test was performed on the real-scale, built-up beam test model fabricated by the $CO_2$ arc spot welding to evaluate the applicability of the welding method to the production of the stiffened plate in car-carrying ship. The built-up beam models which were fixed at both ends in longitudinal direction or simply supported to the rigid foundation, depending on the restraint condition of the corresponding car decks considered, were subjected to simulated design vehicle loads or concentrated point loads. During the test, the central deflection and the longitudinal bending stresses were measured from several points on the longitudinal flange face to predict the section properties of the built-up beams. The longitudinal bending stress on each spot weld were also measured to calculate the average horizontal shear force subjected to spot welds. Test results revealed that the shear strength of spot welds with their current weld nugget size and welding pitch was adequate enough to withstand the horizontal shear forces under the design vehicle loads. Although the built-up beam fabricated by the arc spot welding was a discontinuous beam, its mechanical behavior was well explained by the continuous beam theory using the effective breadth of plate. Based on test results, the criterion for the size of spot weld of which the average shear stress might meet the allowable stress requirement of AWS Code could be established.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.11a
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• pp.146-150
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• 2009

Present family pattern of Korean society has been changed into nuclear family pattern based on the married couple from traditional expanded family pattern. As the entire social consciousness has been changed into private disposition, the number of independent household for 1 person has increases. Also, as the delivery age of first child became late according to the elongation of average period for the national education, the increment of average age for the first marriage and women's participation in the society, the family pattern of married couple lasts longer than used to be. Like this, considering the family formed period comprised from a household for 1 person to a household for 1married couple and senescence increase, as any response is inevitable for the requirement of residential space where 1~2 dwellers' life can be accepted economic and functionally within smaller scaled space, development and research on a plan system(flexible-typed plan) increasing the degree of freedom is required in developing plan of unit household. In the study for this, considering the change of population and social structure, I suggest the method in developing economic design responding to the differentiation, designing the change of support-system and infill-system based on the systemic comprehension about the residing environment in the family formation period and the research for main life pattern and residing environment in the family formation period in the present city life. I will set (family) composing system, develop basic and mixing typed standard model and establish the stage of applied development for the development of economic design.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.747-757
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• 2015

The main purpose of this study is to investigate the static behavior of a horizontally curved prestressed concrete (PSC) girder. A 30m long full-scale curved PSC girder with 80.0m radius is fabricated by a portable curved form system. Deflections and concrete strains at the middle of span were measured. The obtained experimental results have been compared to those from F.E.A. analysis. When a initial crack developed, the applied load was 1.3 times the service design load and the vertical deflection at the middle of span satisfied the requirement for a live load state according to the Korea Bridge Design Specifications (2010). Also, the ductility of the full scale specimen satisfied the limit in the Specifications (2010). To verify the experimental results, a numerical F.E. analysis was carried and confirmed that the data were similar with results from the test above. The horizontally curved PSC girder fabricated on site was found to have enough strength for safety under and after construction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1741-1751
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• 2013

The main purpose of this study is to investigate the static behavior of a prestressed concrete (PSC) girder using pre-tension method. A 30m long full-scale pretension PSC girder is fabricated by the portable fabrication system and tested. All results have been compared to those obtained from F.E.A results. Deflections at the middle of girders have been measured for evaluation. Also, strains of concrete at the middle of span have been measured. From the results of experimental, the load when initial crack was developed was obtained to be 1.75 time the unfactered design load in the full-scale girder specimen. Also, the data of specimen are satisfied the desgin requirements of ductility on the Korea Bridge Design Specification(2010). In service state, the vertical deflection at center of test specimen when a initial crack was developed is satisfied the vertical deflection requirement under live load of the Korea Bridge Design Specification(2010). To verify the experimental results, we numerical analyze the test and confirmed that the data were similar with results from the test above. The pretension girder fabricated in site were found to have enough strength for safety under and after construction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.106-113
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• 2002

In spacecraft system, structure subsystem has the mission of supporting all the components safely under various space environmental conditions. The safety of spacecraft structure is finally verified from the coupled load analysis, which is a branch of load analysis which combines the launch vehicle and satellite. This study introduces the optimization algorithm to reduce the weight of spacecraft structure under launch environmental conditions directly. The acceleration responses are obtained by the introduction of coupled load analysis, which lead to check the failure of spacecraft structural members. The results show a 12% saving of structural weight and this saving is mainly driven by the thickness of honeycomb core, which strongly affects the natural frequencies of platforms and panels.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.561-568
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• 2013

After we designed Bearingless rotor hub system for 7,000lb class helicopter, flexbeam fatigue analysis was conducted for validation of requirement life time 8,000 hours. sectional structural analysis method applying elastic beam model was used. Fatigue analysis for two sections of flexbeam which were expected to weak to fatigue damage from result of static analysis was conducted. Extension, bending and torsion stiffness of flexbeam section shape was calculated using VABS for structure analysis. S-N curve of two composite material which composed flexbeam was generated using wohler equation. Load analysis of bearingless rotor system was conducted using CAMRAD II and load analysis result was applied HELIX/FELIX standard load spectrum to generate bearingless rotor system load spectrum which was used flexbeam fatigue safe life analysis.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.709-716
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• 2005

QoS is an important requirement of the FTTH (Fiber To The Home) subscriber in access network using E-PON (Ethernet Passive Optical Network). In this research, we describe the structure of the access network and propose a bandwidth guarantee scheme for subscriber and service according to the requirements of the subscriber, service and system. This scheme uses two kinds of the classification table, which are called 'service classification table' and 'subscriber classification table.' Using the classification table, we can identify the flow of the subscriber and service. Also, we compute the number of hash table entry to minimize the loss ratio of flows using the M/G/k/k queueing model. Finally, we apply the DRR scheduling through virtual queueing per subscriber instead of the aggregated class.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.299-306
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• 2010

IPTV and VoIP services are considered as killer applications over Mobile WiMAX network, which provideshigh mobility and data rate. Among those which affect the quality of voice in those services, the jitter buffer or playout buffer can compensate the poor voice quality caused by the packet drop due to frequent route change or differences among routes between service endpoints. In this paper, we analyze the correlation between the sleep interval length and jitter buffer size in order to guarantee a predefined level of voice quality. For this purpose, we present an end-to-end delay model considering additional delay incurred by the WiMAX PSC-II sleep mode and a VoIP service quality requirement based on the delay constraints. Through extensive simulation experiments, we also show that the increase of jitter buffer size may degrade the voice quality since it can introduce additional packet drop in the jitter buffer under WiMAX power saving mode.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.487-494
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• 2009

VOD(Video On Demand) that provides streaming service according to the user's requirement in real time, consists of the video streaming server and the client system. Since it is very hard to apply the traditional server-client model that a server communicates with many clients through 1:1 connection to VOD system because it requires very high network bandwidth, many researches have been done to address this problem. Batching technique is one of VOD system based on Multicast that requires very small network bandwidth. However, the batching based VOD system has a limitation that it is very hard to provide VCR(Video Cassette Recorder) ability. In this paper, we propose a technique that reduces the required network bandwidth to provide VCR function by using the characteristic of MPEG, one of international video compression standard. In the proposed technique, a new video stream for VCR function is constructed with I pictures that is able to be decoded independently. The new video stream for VCR function is transmitted with the video stream for normal play together in Batching manner. The performance evaluation result shows that the proposed technique not only reduces the required network bandwidth and memory usage but also decreases the CPU usages.