• Korean Journal of Optics and Photonics
• /
• v.15 no.4
• /
• pp.313-320
• /
• 2004

We present a null testing method fer aspheric surfaces, utilizing a phase-shifting diffraction grating interferometer along with a binary amplitude computer generated hologram (CGH). The binary amplitude CGH is designed to compensate for the wavefront between a point source and the aspheric surface under test. The fringe visibility of the grating interferometer is controlled easily by selecting suitable grating diffraction orders for the measurement and reference wavefronts or by optimizing the groove shape of the grating used. The binary amplitude CGH is designed by numerical analysis of ray tracing and fabricated using e-beam lithography for autostigmatic testing. Experimental results of a large-scale aspheric mirror surface are discussed to verify the measurement performance of the proposed diffraction grating interferometer.

• Journal of Korean Society of Transportation
• /
• v.14 no.2
• /
• pp.119-136
• /
• 1996

The evaluation of risk level or possibility of traffic accidents is a fundamental task in reducing the dangers associated with current transportation system. However, due to the lack of data and basic researches for identifying such factors, evaluations so far have been undertaken by only the experts who can use their judgements well in this regard. Here comes the motivation this thesis to evaluate such risk level more or less in an automatic manner. The purpose of this thesis is to test the fuzzy-logic theory in evaluating the risk level of traffic accidents. In modeling the process of expert's logical inference of risk level determination, only the geometric features have been considered for the simplicity of the modeling. They are the visibility of road surface, horizontal alignment, vertical grade, diverging point, and the location of pedestrain crossing. At the same time, among some inference methods, fuzzy composition inference method has been employed as a back-bone inference mechanism. In calibration, the proposed model used four sites' data. After that, using calibrated model, six sites' risk levels have been identified. The results of the six sites' outcomes were quite similar to those of real world other than some errors caused by the enforcement of the model's output. But it seems that this kind of errors can be overcome in the future if some other factors such as driver characteristics, traffic environment, and traffic control conditions have been considered. Futhermore, the application of site's specific time series data would produce better results.

• Culinary science and hospitality research
• /
• v.14 no.3
• /
• pp.178-195
• /
• 2008

This examination was conducted as follows; 189 copies were coated in total, and demonstratively analyzed by SPSS WIN 15.0 program. The methods used in data for this analysis are as follows; Sensitivity, Reliability, Frequency, Internal consistency, One way ANOVA(Scheffe's examination) Analysis, T-test, etc. The findings of this study are as follows; firstly, it was revealed that respondents who were regular customers of Italian restaurants regarded convenient transportation, property of space, property of pastoral, visibility, and accessibility as importance. This means that Italian restaurant marketers should consider some of factors of location for business with a good view, good parking lot, location at main street, smooth flow of traffic, luxury, atmosphere of freedom, clean area around restaurants, elegant interior of the building, comfortable, luxurious, and deluxe atmosphere, and so on. Secondly, it was revealed that respondents who were regular customers of buffet restaurant either considered the same factors as the Italian restaurants above or regarded those factors less important. This suggests that restaurants should be located on main streets, on trunk roads, and in large-scale residential districts of apartment complex. Thirdly, it was revealed that respondents who were regular customers of traditional restaurants did not consider the locational factors above. This shows that traditional restaurants should be located in nearby customers' houses or their working places, and that marketers should consider focusing on their restaurants' homelike atmosphere, cleanliness, food flavors, and so on.

• Proceedings of the KIEE Conference
• /
• 1998.07b
• /
• pp.477-479
• /
• 1998

This paper presents the results of the field of an improved GPS navigation algorithm. The improved GPS navigation algorithm is a modified Kalman filter which is designed to be ideally suited to car navigation in urban area where lack of GPS visibility is the major problem because of the frequent blockage of the GPS signals by tall buildings and other structures. The method allows the user to estimate its position when the number of visible GPS satellites becomes less than four by using altitude fixing and clock bias estimation techniques. The two estimation techniques are integrated with the Kalman filter in a mutually compensating manner and it is shown that the 3-dimensional position accuracy is well maintained when the number of the visible satellites drops down to two for a reasonable period of time. The post processing results are included to show the improved performance of the modified algorithm over a normal conventional GPS Kalman filter.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.12
• /
• pp.24-28
• /
• 2000

This paper reports a new calculation method of three dimensional deposeition rate by level set method. To model an advancement of the surface efficiently, we have developed a new iteration method to re-initialize the level set function. For calculating etching and deposition rate by direct flow, we have developed a visibility test module and a refraction and re-sputtering model. Sputter deposition rate with shadow effect and surface refraction is calculated. We report that difference of profiles in cases that sticking coefficient are 1.0 and 0.3. We report that the difference of the deposition rate on bottom of the hole is caused by a difference of visible angle by the shadowing effect.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.34 no.2
• /
• pp.92-102
• /
• 2011

Visibility of the flow of goods is an important service element when considering how to improve the quality of a logistics service. Registered mail service of Korea Post, one of logistics service providers, currently supply information on the handling of postal items, such as receipts and delivery and arrival times to customers. However, internally problems related to excessive spending on operating expenses and less reliable tracking and tracing information exist due to errors in the information acquisition and link handling processes, leading to unnecessarily duplicated tasks. Therefore, the purpose of this paper is to propose process optimization method for improving the quality of tracking and tracing information for registered mail items. We analyzed the process and information control system of the current registered mail service and identified the basic causes of the existence of less reliable tracking and tracing information. And we present optimized mail handling and information management process for removing internal problems. Test results using tracking and tracing information examples show a significant performance of the proposed method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.251-256
• /
• 2006

In the work package 'Integrated Positioning' of the research project NAVIO (Pedestrian Navigation Systems in Combined Indoor/Outdoor Environements) we are dealing with the navigation and guidance of visitors of our University. Thereby start points are public transport stops in the surroundings of the Vienna University of Technology and the user of the system should be guided to certain office rooms or persons. For the position determination of the user different location sensors are employed, i.e., for outdoor positioning GPS and dead reckoning sensors such as a digital compass and gyro for heading determination and accelerometers for the determination of the travelled distance as well as a barometric pressure sensor for altitude determination and for indoor areas location determination using WiFi fingerprinting. All sensors and positioning methods are combined and integrated using a Kalman filter approach. Then an optimal estimate of the current location of the user is obtained using the filter. To perform an adequate weighting of the sensors in the stochastic filter model, the sensor characteristics and their performance was investigated in several tests. The tests were performed in different environments either with free satellite visibility or in urban canyons as well as inside of buildings. The tests have shown that it is possible to determine the user's location continuously with the required precision and that the selected sensors provide a good performance and high reliability. Selected tests results and our approach will be presented in the paper.

• The KIPS Transactions:PartD
• /
• v.11D no.6
• /
• pp.1239-1246
• /
• 2004

The integration and union of regional digital map and vehicle location data in e-Logistics which means virtual service architecture based on the Internet among the logistics companies is indispensable clause in order to satisfy the visibility characteristics. Most conventional vehicle monitoring and controlling systems were constructed with individual and mutual exclusive architecture so that there are required lots of cost for sharing and integrating the information among them. In this paper, we design and implement an component-based open system which represent moving object location information as well as digital map using the GML(Geography Markup Language - international standard encoding based on XML). We also test proposed system on the delivery vehicle scenario in e-Logistics environment, and validate its superior in terms of extensibility and interoperability.

• Journal of the Society of Disaster Information
• /
• v.12 no.3
• /
• pp.210-218
• /
• 2016

In this study, the fire analysis program FDS and Pathfinder was used to analysis a simulated accidental fire of a narrow dwelling space as a test bed. The results showed that the evacuation time of the H form internal building structure was the fastest at 285 seconds. In addition, when the automatic sprinkler system functioned with the entrances closed, the temperature distribution was lower and the visible smoke density was reduced.

• Journal of Broadcast Engineering
• /
• v.8 no.2
• /
• pp.136-145
• /
• 2003

This paper proposes a DTV receiver using beamforming techniques to improve indoor and mobile reception. The proposed DTV receiver estimates the directions of arrival (DOAs) of incoming signals using Capon's DOA estimation method and generates an adaptive antenna beam pattern to the estimated DOA of the mainpath signal to Improve the channel condition. After beamforming, a following decision feedback equalizer (DFE) removes the remaining multipath components. The proposed receiver can be implemented with a conventional DTV receiver without anymodification. The performance of the proposed receiver is analyzed with modified Brazilian field test models, which include DOA information of Incoming signals. Simulation results show that the proposed receiver can satisfy the threshold of visibility (TOV) when input signal to noise ratio is slightly over 10 dB.