• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.525-533
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• 2017

Objective: The aim of this study is to investigate maritime officers' strategies to avoid the ship collision in crossing situations. Background: In a situation where there is a risk of collision between two ships, maritime officers can change the direction and speed of the own-ship to avoid the collision. They have four options to select; adjusting the speed only, the direction only, both the speed and direction at the same time and no action. Research questions were whether the strategy they are using differs according to the shipboard experience of maritime officers and the representation method of ARPA (automatic radar plotting aid) - radar graphic information. Method: Participants were 12. Six of them had more than 3 years of onboard experience, while the others were 4th grade students at Korea Maritime and Ocean University. For each participant, 32 ship encounter situations were provided with ARPA-radar information. 16 situations were presented by the north-up display and 16 situations were presented by the track-up display. Participants were asked to decide how to move the own-ship to avoid the ship collision for each case. Results: Most participants attempted to avoid the collision by adjusting the direction of the ship, representing an average of 22.4 times in 32 judgment trials (about 70%). Participants who did not have experience on board were more likely to control speed and direction at the same time than participants with onboard experience. Participants with onboard experience were more likely to control the direction of the ship only. On the other hand, although the same ARPA Information was provided to the participants, the participants in many cases made different judgments depending on the method of information representation; track-up display and north-up display. It was only 25% that the participants made the same judgment under the same collision situations. Participants with onboard experience did make the same judgment more than participants with no onboard experience. Conclusion: In marine collision situations, maritime officers tend to avoid collisions by adjusting only the direction of their ships, and this tendency is more pronounced among maritime officers with onboard experience. The effect of the method of information representation on their judgment was not significant. Application: The results of this research might help to train maritime officers for safe navigation and to design a collision avoidance support system.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.413-421
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• 2017

In this paper, we designed and fabricated a compact UHF receive module for efficient operation such as tactical and operation situation, target location information confirmation, target reset using Link-K(Korean joint tactical data link system). And the effect of target reset was analyzed by simulation. The designed module consists of UHF(ultra high frequency) receiver section, control section, and power distribution section. The UHF receiver section performs frequency down conversion, filtering and automatic gain control, etc. The control section demodulates frequency down-converted signals, extracts information, and performs external interworking. The power distribution section supplies external power, generates and supplies the power required by each section. The fabricated module was dimension of $105{\times}105{\times}80mm$ and weighed 1.10 kg and The receiving distance is more than 50 km.

• The Journal of Society for e-Business Studies
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• v.13 no.1
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• pp.21-32
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• 2008

RFID systems provide technologies of automatic object identification through wireless communications in invisible ranges and adaptability against various circumstances. These advantages make RFID systems to be applied in various fields of industries and individual life. However, it is difficult to use tags with distinction as tags are increasingly used in life because a tag usually stores only one object identifier in common RFID applications. In addition, RFID systems often make serious violation of privacy caused by various attacks because of their weakness of radio frequency communication. Therefore, information sharing methods among applications are necessary for expansive development of RFID systems. In this paper, we propose efficient RFID scheme. At first, we design a new RFID tag structure which supports many object identifiers of different applications in a tag and allows those applications to access them simultaneously. Secondly, we propose an authentication protocol to support the proposed tag structure. The proposed protocol is designed by considering of robustness against various attacks in low cost RFID systems. Especially, the proposed protocol is focused on efficiency of authentication procedure by considering security levels of applications. In the proposed protocol, each application goes through one of different authentication procedures according to their security levels. Finally, we prove efficiency of th proposed scheme compared with the other schemes through experiments and evaluation.

• 대한공업교육학회지
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• v.32 no.1
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• pp.93-116
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• 2007

The purpose of this study was to improve the academic achievement at the public practical center of technical high school in Busan. For this study, 1 class(31 students) in the second grade at "B"technical high school were selected and these students were divided into two groups. One is the experiment group which blended learning was applied to and the other is control group which traditional lecture method was applied to. Each group was divided into three sub-groups by the level of learning ability. Non-randomized control-group pretest-posttest design was applied for this experiment planning. The subject of experiment was the unit of "3D Modeling and Making NC code" in the textbook of "Application of Automatic System" applied by the public practical center of technical high school in Busan. On-line contents were developed and applied to the blended learning to control group. In order to analyze the test result, t-test with a significance level of 0.05 was carried out using SPSS 10.0. The results of this study was summarized as follows; First, as a result of the post test performed on the experiment and the control group, there was a significant difference between two groups, that was, the blended learning was more effective than the traditional lecture method in improving academic achievement. Second, blended learning was more effective than the traditional lecture method in the group of high-leveled and middle-leveled, but was little effective on the low-leveled group. Third, blended learning was more effective than the traditional lecture method in the functional domain, but was little effective in the cognitive domain and psychomotor domain.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.2
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• pp.127-140
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• 2002

In a spatial database system, the semantic integrity should be supported for maintaining the data consistency. In the real world, spatial objects In boundary layer should always meet neighbor objects, and they cannot hold the same name. This characteristic is an implied concept in real world. So, when this characteristic is disobeyed due to the update operations of spatial objects, it is necessary to maintain the integrity of a layer. In this thesis, we propose a spatial-operation-trigger for supporting the integrity of spatial objects. The proposed method is defined a spatial-operation-trigger based on SQL-3 and executed when the constraint condition is violated. A spatial-operation-trigger have the strategy of execution. Firstly, for one layer, the spatial and aspatial data triggers are executed respectively. Secondly, the aspatial data trigger for the other layers is executed. Spatial-operation-trigger for one layer checks whether the executed operation updates only spatial data, aspatial data, or both of them, and determines the execution strategy of a spatial-operation-trigger. Finally, the aspatial data trigger for the other layers is executed. A spatial-operation-trigger is executed in three steps for the semantic integrity of the meet-property of spatial objects. And, it provides the semantic integrity of spatial objects and the convenience for users using automatic correcting operation.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.64-68
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• 2007

This paper describes the development of RF front.end equipment of a wide band high precision satellite navigation receiver to be able to receive the currently available GPS navigation signal and the GALILEO navigation signal to be developed in Europe in the near future. The wide band satellite navigation receiver with high precision performance is composed of L - band antenna, RF/IF converters for multi - band navigation signals, and high performance baseband processor. The L - band satellite navigation antenna is able to be received the signals in the range from 1.1 GHz to 1.6 GHz and from the navigation satellite positioned near the horizon. The navigation signal of GALILEO navigation satellite consists of L1, E5, and E6 band with signal bandwidth more than 20 MHz which is wider than GPS signal. Due to the wide band navigation signal, the IF frequency and signal processing speed should be increased. The RF/IF converter has been designed with the single stage downconversion structure, and the IF frequency of 140 MHz has been derived from considering the maximum signal bandwidth and the sampling frequency of 112 MHz to be used in ADC circuit. The final output of RF/IF converter is a digital IF signal which is generated from signal processing of the AD converter from the IF signal. The developed RF front - end has the C/N0 performance over 40dB - Hz for the - 130dBm input signal power and includes the automatic gain control circuits to provide the dynamic range over 40dB.

• Journal of Broadcast Engineering
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• v.5 no.1
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• pp.94-101
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• 2000

User adaptive reception of broadcast programs includes the functionality such as the user adaptive filtering and browsing functionality. The user adaptive filtering means that the user can limit the list of programs to include only his/her favorite programs among hundreds of available programs. The user adaptive browsing means that the user can view a short summary of his/her selection in the way that he/she prefers. When the receiving system include the random access storage device, the automatic recording functionality of users favorite programs can be included. The user adaptive reception requires support from various meta-data such as user preference data and content description data. TV Anytime forum is a standardization effort to enable user adaptive TV reception, which means that the user can watch what s/he wants when s/he want in the way s/he wants. MPEG-7 includes not only the content description for broadcast applications but also other content descriptions such as structure information. This paper addresses the relationship between MPEG-7 and TV Anytime and investigates how MPEG-7 should be designed and be used to satisfy the requirements of the user adaptive reception of broadcast program.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.226-233
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• 2013

In this study, In Laver's automatic drying device, laver thickness measurement and control devices that are associated with. Disconnect the water and steam, after put a certain amount of the mixture(water and laver) in the mold. In process, Laver of the size and thickness (weight) to determine, constant light source to detect and image LED Lamp occur Vision Sensor (Camera) prepare, then the values of these state of the image is transmitted in real time embedded computers. Built-in measurement and control with the purpose of the application of each of the channels separately provided measurements are displayed on a monitor, And servo signals sent to each of the channels and it become so set function should be. In this paper, the laver drying device, prior to the laver thickness measurement and control devices that rely on the experience of existing workers directly laver manually adjust the thickness of the lever, but the lever by each channel relative to the actuator by installing was to improve the quality. In addition, The effect of productivity gains and labor savings are.

• The KIPS Transactions:PartD
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• v.13D no.5 s.108
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• pp.641-650
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• 2006

XML has the characteristics of self-describing and uses DTD or XML schema in order to constraint its structure. Even though the XML schema is only at the stage of recommendation yet, it will be prevalently used because DTD is not itself XML and has the limitation on the expression power. The structure defined by the XML schema as well as the data of the XML documents can vary due to complex reasons. Those reasons are errors in the XML schema design, new requirements due to new applications, etc. Thus, we propose XML schema evolution operators that are extracted from the analysis of the XML schema updates. These schema evolution operators enable the XML schema updates that would have been impossible without supporting tools if there are a large number of XML documents complying the U schema. In addition, these operators includes the function of automatically finding the update place in the XML documents which are registered to the XSE system, and maintaining the XML documents valid to the XML schema rather than merely well-formed. This paper is the first attempt to update XML schemas of the XML documents and provides the comprehensive set of schema updating operations. Our work is necessary for the XML application development and maintenance in that it helps to update the structure of the XML documents as well as the data in the easy and precise manner.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.177-183
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• 2002

Current state-of-the-art of VMS control is based upon simple knowledge-based inference engine with message set and each message's priority. And R&Ds of the VMS control are focused on the accurate detection and estimation of traffic condition of the subject roadways. However VMS display itself cannot achieve a desirable traffic allocation among alternative routes in the network In this context, VMS display strategy is the most crucial part in the VMS control. VMS itself has several limitations in its nature. It is generally known that VMS causes overreaction and concentration problems, which may be more serious in urban network than highway network because diversion should be more easily made in urban network. A feedback control algorithm is proposed in this paper to address the above-mentioned issues. It is generally true that feedback control approach requires low computational effort and is less sensitive to models inaccuracy and disturbance uncertainties. Major features of the proposed algorithm are as follows: Firstly, a regulator is designed to attain system optimal traffic allocation among alternative routes for each VMS in the network. Secondly, strategic messages should be prepared to realize the desirable traffic allocation, that is, output of the above regulator. VMS display strategy module is designed in this context. To evaluate Probable control benefit and to detect logical errors of the Proposed feedback algorithm, a offline simulation test is performed using real network in Daejon, Korea.