• Korean Journal of Environment and Ecology
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• v.18 no.2
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• pp.249-262
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• 2004

This study was conducted to suggest alternatives for the effective use of national park visitor centers, by evaluating their functionality. Visitor centers in Naejangsan National Park and Pukhansan National Park, which are deliberately composed and managed, were investigated for this purpose. First, I clarified the concept, function and type of a visitor center through literature review, and then, analyzed visitors' post-visiting evaluation based on McManus's Communication Theory. The results of the analysis shows that visitors have not enough time to understand the contents of visitor centers, and facilities and guide sign system to support visitors are insufficient, which seem to disturb the proper communication between visitors and exhibits. Visitors' short visiting time caused by their little interest in exhibits and their low degree of understanding show the difficulties in the communication between visitors and exhibits. The following alternatives are suggested to improve these problems: first, the improvement of the guide sign system; second, the provision of exhibition rooms specialized for different visitor groups; third, the display of exhibits connected with visitors' experiences; Forth, the utilization of various media proper for each subject.

• The KIPS Transactions:PartA
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• v.10A no.3
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• pp.247-254
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• 2003

This paper describes a Delay Locked Loop (DLL) with low supply voltage and wide lock range for Synchronous DRAM which employs Double Data Rate (DDR) technique for faster data transmission. To obtain high resolution and fast lock-on time, a new type of phase detector is designed. The new counter and lock indicator structure are suggested based on the Dual-clock dual-data Flip Flop (DCDD FF). The DCDD FF reduces the size of counter and lock indicator by about 70%. The delay line is composed of coarse and fine units. By the use of fast phase detector, the coarse delay line can detect minute phase difference of 0.2 nsec and below. Aided further by the new type of 3-step vernier fine delay line, this DLL circuit achieves unprecedented timing resolution of 25psec. This DLL spans wide locking range from 500MHz to 500MHz and generates high-speed clocks with fast lock-on time of less than 5 clocks. When designed using 0.25 um CMOS technology with 1.8V supply voltage, the circuit consumes 32mA at 500MHz locked condition. This circuit can be also used for other applications as well, such as synchronization of high frequency communication systems.

• Journal of Advanced Navigation Technology
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• v.14 no.3
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• pp.452-458
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• 2010

In case of an embedded system with computing resource restrictions such as system power and cpu, the overhead due to displaying data on the computer screen may have a significant influence on the system performance. This paper describes an initialization method for LCD-driving components such as an ARM Core, an LCD controller, and an SPI(serial peripheral interface). It also introduces a pixel display function and a panel display method using virtual screen for reducing the display overhead for an LN2440SBC system with an ARM9-based S3C2440A microprocessor. A virtual screen is a large space of computer memories allocated much larger than those needed for one-time display of an image. Displaying a specific region of a virtual screen is done by assigning it as a view-port region. Such a display is useful in an embedded system when concurrently running tasks produce and display their respective results on the screen; it is especially so when the execution result of each task is partially modified, instead of being totally modified, on its turn and displayed. If the tasks running on such a system divide and make efficient use of the region of the virtual screen, the display overhead can be minimized. For the performance comparison with and without using the virtual screen, two different images are displayed in turn and the amount of time consumed for their display is measured. The result shows that the display time of the former is about 5 times faster than that of the latter.

• Journal of IKEEE
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• v.18 no.3
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• pp.383-391
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• 2014

In this paper, temperature, pressure and flow analysis system for testing a fuel filter of a diesel engine at the low-temperature environment in winter, is proposed. The light oil of diesel engine below a specific temperature is changed to the waxing materials like paraffin, and it prevents engine to start easily because of reducing fluidity. Thus, built-in block heater should be installed with fuel filter in order to solve this problem. And it is necessary to design evaluation system that can analyze the performance according to temperature, pressure and flow characteristics near fuel filter at a very low temperature. In this paper, we measured a physical quantity related to the performance of around the fuel filter using the proposed system, and analyzed their characteristics. Also the measured data is transferred to remote user by using a web server of embedded systems, and analyzed their conditions in remote place via web browser in order to know the operating status of fuel filter. We installed the proposed system in a small test chamber to verify the performance and took an experiment in normal temperature and very low temperature, and could obtain temperature, pressure and flow of near the fuel filter. As a result, the fuel flow could be improved during operation of the fuel heater.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.157-165
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• 2000

A small hydraulic winch system with an automatic tension control unit was designed to improve the work efficiency of coastal small vessels and the dynamic response characteristics of the winch system operated in the open loop condition was investigated. The inlet and the outlet pressures in hydraulic motor, the torque and the rotating speed of winch drum were measured as a function of time, and the behaviour in autotension mode for stepped load changes was analyzed. The results obtained are summarized as follows : 1. The developed winch system for coastal small vessels will result in better fishing with improved efficiency and lower manpower consumption by remote control of winch system. 2. The rotating delay times of winch drum for on/off operations of solenoid valve were 0.09 see at CW mode and 0.04 sec at CCW mode, respectively. After the solenoid valve was controlled, response characteristics were unstable slightly but showed good tracking behaviour over short time. 3. The driving torque of winch system in autotension mode was kept almost constant of 55.9 kgf·m, and 11.1 then the rotating speed of winch drum was kept almost constant of 5.1 rpm in the larger torque than 55.9 kgf·m and 11.1 rpm in the lower torque than that. 4. The 5% settling times in the transient response characteristics of autotension mode under rapid increasing and decreasing conditions of load were 0.12 sec and 0.2 sec, respectively, and then the rotating speeds were 11 rpm and 5.3 rpm, respectively. 5. The tracking behaviour of torque and rotating speed by remote control operation were stable within 0.23 sec at CW mode and 0.37 sec at CCW mode, respectively.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.183-192
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• 2012

Although underground water resource has relatively less pollution rate compared with surface water, its recovery faces many difficulties due to poor management. Our country monitors underground water to manage it effectively through auxiliary observation network for underground water. In this paper, we suggest water-well auto measure system based on Geosensor for business efficiency increase of water-well management and realtime monitering. In this system is consist of user GUI(Graphic User Interface) composed with water-well information and movement sub-observation network prototype system composed with GPS(Global Positioning System) and wireless sensor node such as water temperature, water level, electrical conductivity. In this system is using the light of the sun for self-power, variety water-well information collected wireless sensor node was a wireless transmitting/receiving a using CDMA(Code Division Multiple Access) module. Also, for promote with user ease, user GUI express that water-well collected in GIS(Geographic Information System) map. For performance evaluation of the proposed system, we perform experiment using sensing information through designed sub-observation network. And we was proved superiority of the proposed system through qualitative evaluation with other paper.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.5
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• pp.429-437
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• 2022

Recently, the demand for a QA (Question Answering) system for human-machine communication has increased. Among the QA systems, a closed domain QA system that can handle spatial-related questions is called GeoQA. In this study, a new type of graph database, LPG (Labeled Property Graph) was used to overcome the limitations of the RDF (Resource Description Framework) based database, which was mainly used in the GeoQA field. In addition, GraphQL (Graph Query Language), an API-type query language, is introduced to address the fact that the LPG query language is not standardized and the GeoQA system may depend on specific products. In this study, database was built so that answers could be retrieved when spatial-related questions were entered. Each data was obtained from the national spatial information portal and local data open service. The spatial relationships between each spatial objects were calculated in advance and stored in edge form. The user's questions were first converted to GraphQL through FOL (First Order Logic) format and delivered to the database through the GraphQL server. The LPG used in the experiment is Neo4j, the graph database that currently has the highest market share, and some of the built-in functions and QGIS were used for spatial calculations. As a result of building the system, it was confirmed that the user's question could be transformed, processed through the Apollo GraphQL server, and an appropriate answer could be obtained from the database.

• Journal of the Korea Society of Computer and Information
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• v.27 no.8
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• pp.77-84
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• 2022

In this paper, we propose a system for monitoring air pollutants such as fine dust using an unmanned aerial vehicle capable of autonomous navigation. The existing air quality management system used a method of collecting information through a fixed sensor box or through a measurement sensor of a drone using a control device. This has disadvantages in that additional procedures for data collection and transmission must be performed in a limited space and for monitoring. In this paper, to overcome this problem, a GPS module for location information and a PMS7003 module for fine dust measurement are embedded in an unmanned aerial vehicle capable of autonomous navigation through flight information designation, and the collected information is stored in the SD module, and after the flight is completed, press the transmit button. It configures a system of one-stop structure that is stored in a remote database through a smartphone app connected via Bluetooth. In addition, an HTML5-based web monitoring page for real-time monitoring is configured and provided to interested users. The results of this study can be utilized in an environmental monitoring system through an unmanned aerial vehicle, and in the future, various pollutants measuring sensors such as sulfur dioxide and carbon dioxide will be added to develop it into a total environmental control system.

• Journal of KIISE:Software and Applications
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• v.27 no.5
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• pp.473-487
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• 2000

SDL-92, the language for specification and description of system, has held on to the communication method that based on processes and signals in the adoption of object-oriented concept to embrace the previous documents of system specification and description and users. It has caused problems, not only the absence of corresponding concepts in automatic generation to object-oriented language program based on method and object, but also some side effects accompanied by them like visibility and communication method. So, in this paper, we present a general object-oriented language model, which based on method and object, make a study of problems in the transformation fromSDL-92 to proposed model, and then propose conceptual transformation methods to solve them. The proposed transformation method can utilize the built-in parallelism in objects and guarantee the compiler level portability in translated program by providing translation into the syntax of target language.

• Journal of the Korea Society of Computer and Information
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• v.18 no.4
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• pp.183-190
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• 2013

Many researchers in the 21st century has found that robot education is effective to develop the learners' creativity and problem-solving ability. However, the robot education can only be applied to the students whose computer skills are high. Also it can be taught in the well-prepared computer classroom. Students have to learn machine language to control their robots, and robots are controlled by different types of software. Therefore this study has constructed command-based programming blocks to do a robot programming without computers. It also presents a prototype of the programming process and a technological method to combine the command and the programming blocks. We used the blocks which are similar with something in flow chart: to support intuition, and to help students transfer what they learned. And types of blocks and details are described for the Robot Programing Education. Combination of command blocks is made by RS-485 connection method and, it is designed to intercommunicate with connected blocks. It also presents a prototypes: of the programming process using designed command blocks, and of the possibility of Unplugged Robot Education System.