• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.10 no.5
• /
• pp.20-25
• /
• 2011

In this paper, we reviewed the spindle system's motor and bearing and its mode safety for optimal design of a high speed spindle system that exceeds DmN value of 1,500,000. We could verify that it has a separation margin during critical speed by performing critical speed analysis. Also, we have selected an optimal sensoring installation location and actually manufactured & installed the sensor by identifying the stress concentration position in the axial load through finite element analysis to install the built-in piezo electric type load sensor to the spindle housing that can measure and monitor the machining load during high speed rotation of the spindle. Reproducibility is also verified by calibrating the error through the sensor's sensitivity adjustment after comparing the output between the plate dynamoneters and the load sensor to confirm the reproducibility of the load sensor.

• International journal of advanced smart convergence
• /
• v.5 no.3
• /
• pp.16-26
• /
• 2016

This proposed project is about a bicycle anti theft devised system which helps people protect the bicycle from theft and helps to track the stolen bicycle's location using a smart phone. Safety bike uses two main devices to keep the bicycle secured, the vibration sensor and GPS sensor. The purpose of this project is to put all these small devices into one well connected system which will help the bicycle owner have more control over the security of his own bicycle. The whole system can be divided into two main parts. The first part is about the hardware development whereby all electronics components are connected via the circuit design using wire wrapping technique. This hardware part includes, a vibrations sensor, a GPS receiver, a toggle switch, LED light, Bluetooth and a buzzer. Wireless Bluetooth signals are used as the means of communication between the smartphone and the microcontroller. The second part is the software part which is being to program and control the whole system. The program is written using MikroBasic, a full-featured Basic compiler for microcontroller based systems. In conclusion, this system is designed to enable user to have control in securing his/her bicycle also being able to find and locate it at any time using GPS receiver and mobile android application.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.8 no.5
• /
• pp.423-433
• /
• 2016

In this paper, we consider the cybersecurity issue of ship information system (SIS) from a new perspective which is called opacity. For a SIS, its confidential information (named as "secret") may be leaked through the working behaviors of each Distributed Control Unit (DCU) from an outside observer called an "intruder" which is able to determine ship's mission state by detecting the source of each data flow from the corresponding DCUs in SIS. Therefore we proposed a dual layer mechanism to enforce opacity by activating non-essential DCU during secret mission. This mechanism is calculated by two types of insertion functions: Safety-assured insertion function ($f_{IS}$) and Admissibility-assured insertion function ($f_{IA}$). Due to different objectives, $f_{IS}$ is designed to confuse intruder by constructing a non-secret behaviors from a unsafe one, and the division of $f_{IA}$ is to polish the modified output behaviors back to normal. We define the property of "$I_2$-Enforceability" that dual layer insertion functions has the ability to enforce opacity. By a given mission map of SIS and the marked secret missions, we propose an algorithm to select $f_{IS}$ and compute its matchable $f_{IA}$ and then the DCUs which should be activated to release non-essential data flow in each step is calculable.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.5
• /
• pp.888-908
• /
• 2011

The increasing demand from passengers in vehicles to improve safety, traffic efficiency, and comfort has lead to the growing interest of Wi-Fi based vehicle-to-infrastructure (V2I) communications. Although the V2I system provides fast and cost-effective Internet connectivity to vehicles via roadside Wi-Fi access points (APs), it suffers from frequent handoffs due to the high mobility of vehicles and the limited coverage of Wi-Fi APs. Recently, the Mobile AP (MAP) platform has emerged as a promising solution that overcomes the problem in the V2I systems. The main advantage is that MAPs may yield longer service duration to the nearby vehicles that have similar mobility patterns, yet they provide smaller link capacities than the roadside APs. In this paper, we present a new association control technique that harnesses available connection duration as well as achievable link bandwidth in high-speed vehicular network environments. We also analyze the tradeoff between two association metrics, namely, available connection duration and achievable link bandwidth. Extensive simulation studies based on real traces demonstrate that our scheme significantly outperforms the previous methods.

• Korean Journal of Adult Nursing
• /
• v.28 no.6
• /
• pp.669-679
• /
• 2016

Purpose: The purpose of this study was to explore the reported good service experiences from the perspective of elderly residents of long-term care facilities. Methods: Of those residents who are 65 years old or older, 14 residents whose length of stay were one month or longer and scores of the K-Mini Mental State Examination were 15 or higher were interviewed. The interview data formed the basis for the empirical statements about the reported nature of patients' experiences as residents of long-term care facilities. These data were used in concept mapping. Results: Through multidimensional scaling analysis and hierarchical cluster analysis, 62 core statements, two dimensions, and six clusters of good service experiences were derived. The two dimensions were classified as 'care centered-participation centered services' and as 'physical-emotional services.' Six cluster themes emerged as good service experiences: 'safety of care and treatment', 'responsible and supportive staff', 'comfort of living environment', 'mental well-being', and 'respect and communication'. Conclusion: The result of the study provides information about what experiences are important to older adults with cognitive impairment. The concept map can be used to develop a patient experience index for the elderly residents of long-term care facilities.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.34 no.6
• /
• pp.547-557
• /
• 2016

Due to threats caused by social disasters, operating surveillance devices are essential for social safety. CCTV, infrared cameras and other surveillance equipment are used to observe threats. This research proposes a method for searching for the optimum location of surveillance sensors. A GA (Genetic Algorithm) was used, since this algorithm is one of the most reasonable and efficient methods for solving complex non-linear problems. The sensor specifications, a DEM (Digital Elevation Model) and VITD (Vector Product Interim Terrain Data) maps were used for input data. We designed a chromosome using the sensor pixel location, and used elitism selection and uniform crossover for searching final solution. A fitness function was derived by the number of detected pixels on the borderline and the sum of the detection probability in the surveillance zone. The results of a 5-sensor and a 10-sensor were compared and analyzed.

• Journal of Welding and Joining
• /
• v.33 no.1
• /
• pp.24-29
• /
• 2015

Residual stresses arising from the materials processing such as welding and joining affect significantly the structural integrity depending on the external loading condition. The quantitative measurement of the residual stresses is of great importance in order to characterize the effects of the residual stresses on the structural safety. In this paper, we introduce a newly devised destructive technique, the contour method (CM), which is applied for the measurements of the residual stress distributions through the thickness of a 80 mm thick steel weld. Residual stresses are evaluated from the contour, which is the normal displacement on a cut surface produced by the relaxation of residual stresses, using a finite element model. The CM provides a two-dimensional map of the residual stresses normal to the cut surface. The CM developed in the present study was validated in comparison with the residual stress distribution determined by a well-established neutron-diffraction residual stress instrument (RSI) instrumented in HANARO neutron research reactor.

• Nuclear Engineering and Technology
• /
• v.48 no.5
• /
• pp.1126-1139
• /
• 2016

In this research, for the first time, a new optimization method, i.e., strength Pareto evolutionary algorithm II (SPEA-II), is developed for the burnable poison placement (BPP) optimization of a nuclear reactor core. In the BPP problem, an optimized placement map of fuel assemblies with burnable poison is searched for a given core loading pattern according to defined objectives. In this work, SPEA-II coupled with a nodal expansion code is used for solving the BPP problem of Kraftwerk Union AG (KWU) pressurized water reactor. Our optimization goal for the BPP is to achieve a greater multiplication factor ($K_{eff}$) for gaining possible longer operation cycles along with more flattening of fuel assembly relative power distribution, considering a safety constraint on the radial power peaking factor. For appraising the proposed methodology, the basic approach, i.e., SPEA, is also developed in order to compare obtained results. In general, results reveal the acceptance performance and high strength of SPEA, particularly its new version, i.e., SPEA-II, in achieving a semioptimized loading pattern for the BPP optimization of KWU pressurized water reactor.

• Journal of Korean Society for Geospatial Information Science
• /
• v.23 no.3
• /
• pp.85-93
• /
• 2015

This paper mainly introduces the methods of extracting landslide information using ALOS(Advanced Land Observing Satellite) images and GIS(Geographical Information System) technology. In this study, we classified images using three different methods which are the unsupervised the supervised and the PCA(Principal Components Analysis) for extracting landslide information based on characteristics of ALOS image. From the image classification results, we found out that the quality of classified image extracted with PCA supervised method was superior than the other images extracted with the other methods. But the accuracy of landslide information extracted from this image classification was still very low as the pixels were very similar between the landslide and safety regions. It means that it is really difficult to distinguish those areas with an image classification method alone because the values of pixels between the landslide and other areas were similar, particularly in a region where the landslide and other areas coexist. To solve this problem, we used the LSM(Landslide Susceptibility Map) created with ArcView software through weighted overlay GIS method in the areas. Finally, the developed LSM was applied to the image classification process using the ALOS images. The accuracy of the extracted landslide information was improved after adopting the PCA and LSM methods. Finally, we found that the landslide region in the study area can be calculated and the accuracy can also be improved with the LSM and PCA image classification methods using GIS tools.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.8
• /
• pp.509-514
• /
• 2010

A numerical simulation of passenger evacuation in a subway station was performed by coupling the passenger flow analysis and the fire simulation. The algorithm of the passenger flow analysis was based on a DEM (Discrete Element Method) using the potential map of the direction vector for each passenger. This algorithm was improved in the present study as to use finer grid smaller than a passenger in order to resolve detailed geometry of the station and to resolve the behavior of passengers in the bottleneck at the ticket gate considering the collision of passengers to a wall or with other passengers. In the fire simulation, the CO distribution predicted by using CFD was used to take into account the effect of toxic gases on the passengers' mobility. The methodology proposed in the present study could be used in designing safer subway station in case of fire occurrence.