• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.265-272
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• 2011

This study designed and manufactured "a DVOR virtual signal generator" to make the monitoring system of preliminary Doppler VHF Omni-directional Radio Range(DVOR) run like its real operation status in a narrow space in order to study "a DVOR virtual monitoring system". The designed and manufactured DVOR virtual signal generator is suitable for the specification of signal that is generated in the currently running equipment. In addition, it is possible to control operation conditions of equipment by using parameter variables, and the circuit construction is largely divided into the input part, the modulation part, the high-gain amplifier, and the power part. "The DVOR virtual monitoring system using the virtual signal designed and implemented in this study is very suitable to be used for low-cost actual education as it can construct the operation status like the real situation in a narrow space without using an actual system like an antenna generating side band.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.169-170
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• 2012

The efforts for improving 'Maritime Traffic Safety Assessment Scheme(MTSA scheme)' have continued to the present since May 27th, 2009. But recently, there's a controversy about whether it has been performed properly or the results is significant. These new discussions were arose from lack of validity and appropriateness we had yet to find. At this point, it needs to establish sound MTSA scheme through the comprehensive review. This research developed a suitable meta-evaluation model for MSTA with applying theory of the teta-evaluation, that is the evaluation of evaluations and verified by using meta-evaluation methods like as literature studies, expert reviews, surveys and etc. The results of this study can be used to evaluate MTSA activities and it will contribute to improving MTSA scheme.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.87-94
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• 2009

Volume of concrete slab changes by variations of temperature and moisture after its placement. Shrinkage due to evaporation causes tensile stress in the slab when contraction of the slab is restrained by its self weight, friction with subbase, and etc. Actual tensile stress caused by the shrinkage was less than theoretically predicted stress according to previous studies. It was the stress reduction due to visco-elastic property of the early-age concrete slab partially restrained. In this study, strains of restrained circumferential, unrestrained circumferential, and unrestrained square pillar concrete specimens were measured to investigate stress reduction of the specimens with age of concrete. Elastic modulus of the concrete was measured at the age of 1, 3, 7, 14, 28 days and penetration test was performed. The stress reduction was calculated by input the test results into theoretical equations suggested by previous researchers. The stress reduction of the restrained concrete specimens will be applied to design of concrete pavements based on results of the study.

• Tribology and Lubricants
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• v.31 no.2
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• pp.35-41
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• 2015

A water-pump located in the cooling area of a car circulates cooling water. A particular bearing element, known as a water-pump bearing, installed in the rotating part carries the entire load. The failure of this water-pump bearing has a direct impact on the failure of the automobile engine, and so securing its reliability is crucial. Several researchers have examined the design principles of the water-pump bearing, but there are no reports on the life characteristic of the bearing yet. Herein, we report the construction of test equipment to reproduce the spalling of the roller contact, which is the main failure mode of the chosen water-pump bearing. We chose the radial load as an accelerated stress factor and validated the failure mode by monitoring the surface defects. We conducted the accelerated life test after determining the accelerated stress level through a combination of finite element analysis and a preliminary test. In the life tests, we used an accelerometer to perform failure diagnosis. In the last stage of this study, we present a statistical reliability analysis. Thus, we fully estimated the shape parameter of the water-pump bearing, accelerating level on the load , and the lifetime (MTTF and B₁₀ life) under real use conditions, and finally proposed an interval estimation value considering the uncertainty of the estimated value.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1197-1205
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• 1988

An analytical method to predict qualitative performance characteristics of the Stirling Engines in the preliminary design stages is investigated. Both the expansion and the compression cylinder are treated as adiabatic and piston motions are approximated as saw-toothed waves. Basic equations which were originally proposed by Finkelstein consist of mass conservation and energy balances for each adiabatic cylinder. The approximation on piston motions and physical conditions make it possible to divide an engine cycle into four fundamental processes. In each process, first, pressure can be expressed as a function of the crank angle by solving a nonlinear first order ordinary differential equation and other thermodynamic variables are determined in turn. Application of the cyclic steady condition to the whole processes can complete a cycle. Also, further analysis results in analytic expressions for cyclic work and heat transfer in terms of the engine parameters and thermodynamic variables at boundary points. The results are expected useful as a quick reference for the engine performances. Finally, the present method can be applied to the other adiabatic analyses on the Stirling Engines with piece wise linear piston motions, if mass variations are predictable.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.11
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• pp.899-905
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• 2014

This paper describes preliminary research conducted for developing a high-efficiency clean large cauldron using the liquid-vapor phase change heat transfer. To improve the isothermal environment of the cauldron, naphthalene and FC-40 were selected as the working fluids to operate well in the temperature range of $100-200^{\circ}C$ and used in experimental investigations of the heat transfer characteristics. A two-phase closed thermosyphon was designed and built to demonstrate the functionality of the working fluids. Startup, boiling, and condensation tests were performed, and the test results were used to examine the possibility of complementary effects of the startup and heat transfer characteristics of the two-phase closed thermosyphon using a mixture of naphthalene and FC-40.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.1058-1067
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• 2017

The purpose of this study was to develop the NCS-based cooking practice education method by using the full learning model and to confirm its effect. The study design was a pre-post test of the non-equality control group. The subjects of this study included 28 students in the experimental group and 27 students in the control group. The experimental group participated in the NCS-based cooking practice training using the complete learning model, and the control group received only cooking practice training based on the full learning model. The data were collected during the second semester of 2016 and analyzed by SPSS WIN 23.0. The results of this study were as follows: First, homogeneity test showed that pre - homogeneity such as general characteristics, cooking ability, and knowledge of cooking theory were achieved (p>0.05). Second, the experimental group recognized that its cooking ability was high. With respect to the ability to cook food, the ability to cook, and the ability to prepare food ingredients (p<0.01), personal hygiene management, cooking hygiene management, and cooking safety management abilities were not significant. The mean value the experimental group was high. Third, the final theoretical knowledge score was not significant. The average score in the experimental group (69 points) was 5 points higher than that in the control group (64 points). This was about two times higher than the score of 37 points in the first stage preliminary survey. Finally, the final performance score was significant (p<0.05), and the score in the experimental group (89 points) was 5 points higher than that in the control group (84 points). Therefore, the NCS-based cooking education method is confirmed to be an effective method, especially for improvement of the practical ability, improvement of theoretical knowledge, and achievement of perfect learning standards.

• Journal of Navigation and Port Research
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• v.32 no.6
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• pp.473-479
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• 2008

Recently the trade patterns of the entire economy are rapidly changing on development of IT. The field of port logistics is enforcing a competitiveness through preliminary offer of information and a batch process for improving the structure of logistics management which is apparently high cost and the low efficiency since 1990. But a previous EDI is insufficient in process ability. Bemuse it costs for the purchasing and maintenance of the expensive communication devices which is operated on the VAN environment. A web based EDI operating on an open network environment is needed to improve these problems and to handle transaction efficiently among many and unauthorized personals. Therefore, this study is willing to present a new web based model of the pull process which extracts the data when the receiver is needed to improve the push process which is transmitting data unilaterally.

• Journal of the Korean Geotechnical Society
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• v.33 no.5
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• pp.37-44
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• 2017

In this study, three dimensional numerical analyses were carried out to predict axial (pullout and compressive) and lateral behavior of rock-socketed steel pipe pile varying diameter, wall thickness, and length. As a result of the pile pullout analyses, it was confirmed that the pullout displacement was inversely proportional to the pile diameter for given pile length, thickness, pullout load. Load-settlement relationship of the compressive pile analyses revealed that the effect of pile thickness on pile resistance was more significant than that of pile diameter. In addition, laterally loaded pile analyses showed that pile lateral resistance is influenced above all else by pile diameter. This study showed that it is necessary to conduct numerical analyses to identify the effects of pile diameter, wall thickness, and pile length on the steel pipe pile behavior as a preliminary pile design under specified loading conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.46-52
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• 2008

In this paper, we present the Mont-Saint-Michel virtual reality system designed to create the virtual heritage environment, which is enriched with personalized tour guide service. The tour guide system allows users to travel in the virtual heritage site and get more information about the sites or items of user's interests. It also allows users to make their own tour guidebook with the pictures they have taken during the virtual tour and more detail descriptions from the tour guide database. It then generates the web-based tour guidebook for users to utilize it for the actual site visit or share it with others over the Internet. The components of this system are designed with the consideration of reusability to be used for other interactive tour guide systems. This paper describes the motivation the development and a preliminary user study of Mont-Saint-Michel virtual reality personalized tour guide system.