• Journal of The Korean Association of Information Education
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• v.6 no.3
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• pp.328-337
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• 2002

Looking at multimedia education contents from a design point of view, the instructor's design model may differ from the child's understanding model due to gap of the instructor's and child's knowledge. This fact implies it impacts the effectiveness of the education contents. The learning efficiency of Korean typography in WBI for children depends on the font-family, line space, font-size, the age of user, the output device such as the monitor, and other various factors. In this paper, we measured and analyzed on readability of Korean typography in WBI for children by reading speed method. The results of experiments show that readability depends on the font-family of typography, age(grade), and sex of children. In detail, "Goolymche" has the shortest time to be read, and girl and the highest grade students of elementary school have shorter time than boy and the lower grade students. Moreover, we consider the elegance of typography in WBI for holding children's interests because they prefer "Yopseoche". We provide some CSSs in WBI for children based on the experimental results, to used in school fields.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.135-150
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• 2005

In this paper, we propose an integrated information retrieval system for distributed multiple KRISTAL-2002 systems by using the metadata information. This system integrates current systems for different areas or systems for the same area with the different schemas so that the users can get the answers by once from the whole systems. The proposed system composes of the Source Server Manager(SSM) supporting the mapping between the integrated metadata database and source server, the Integrated Metadata Manager(ISM) for registering and managing the metadata and schema mapping, the Distributed Query Processor (DQP) for processing the user query into the source server query, the Distributed Data Set Integrated Manager(DDSIM) for transforming the total retrieval results by merging to the HTML format, and the integrated retrieval engine for managing the query results. It is assumed that the integrated metadata follows ISO/IEC 11179 metadata registration procedure with the metadata registry system which is a subsystem of the proposed system. There are two kinds of queries for users; the basic query and the detailed query. The users may select the databases or organizations for results by their own choices before giving the queries. The proposed system has been developed over KRISTAL-2002 systems with $Visual C^{++}\;and\;C^{++}-CGI$ and tested and verified with the six database systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.554-561
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• 2017

IoT (Internet of Things) devices are often located in environments where indoor or underground, signals are difficult to reach. In addition, the transmission power is low, the base station should be designed to be able to receive signals even at low reception sensitivity. For this reason, a device having a poor channel condition can be transmitted at a low data rate using a low coding rate or repetition. When the coverage class is divided according to the channel condition and the data rate, the packet length may vary from one coverage class to another, and the performance of the slotted aloha random access may be degraded. We will focus on two methods of using shared-resource and seperate resources among multiple slotted aloha methods. In particular, when devices with different coverage classes use shared resources, performance of a device with a bad channel condition may deteriorate. Conversely, when using separate resources for each coverage class, there is a problem that congestion may occur which increases the number of devices that perform random access to one resource area. In this paper, we propose some methods to overcome this problem. This study is mainly focused on MTC devices, and is considered to be a high possibility of future development.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.587-596
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• 2022

Sea levels are rising as a result of climate change, and low-lying areas along the coast are at risk of flooding. Therefore, we tried to investigate the relationship between sea level change and climate indices using satellite altimeter data (Topex/Poseidon, Jason-1/2/3) and southern oscillation index (SOI) and the Pacific decadal oscillation (PDO) data. If time domain data were converted to frequency domain, the original data can be analyzed in terms of the periodic components. Fourier transform and Wavelet transform are representative periodic analysis methods. Fourier transform can provide only the periodic signals, whereas wavelet transform can obtain both the periodic signals and their corresponding time location. The cross-wavelet transformation and the wavelet coherence are ideal for analyzing the common periods, correlation and phase difference for two time domain datasets. Our cross-wavelet transform analysis shows that two climate indices (SOI, PDO) and sea level height was a significant in 1-year period. PDO and sea level height were anti-phase. Also, our wavelet coherence analysis reveals when sea level height and climate indices were correlated in short (less than one year) and long periods, which did not appear in the cross wavelet transform. The two wavelet analyses provide the frequency domains of two different time domain datasets but also characterize the periodic components and relative phase difference. Therefore, our research results demonstrates that the wavelet analyses are useful to analyze the periodic component of climatic data and monitor the various oceanic phenomena that are difficult to find in time series analysis.

• Journal of the Korea Society of Computer and Information
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• v.14 no.9
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• pp.11-19
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• 2009

A RAM-based Neural Net(RBNN) which has multi-discriminators is more effective than RBNN with a discriminator. Experience Sensitive Cumulative Neural Network and 3-D Neuro System(3DNS) that accumulate the features point improved the performance of BNN, which were enabled to train additional and repeated patterns and extract a generalized pattern. In recognition process of Neural Net with multi-discriminator, the selection of class was decided by the value of MRD which calculates the accumulated sum of each class. But they had a saturation problem of its memory cells caused by learning volume increment. Therefore, the decision of MRD has a low performance because recognition rate is decreased by saturation. In this paper, we propose the method which improve the MRD ability. The method consists of the optimum MRD and the matching ratio prototype to generalized image, the cumulative filter ratio, the gap of prototype response MRD. We experimented the performance using NIST database of NIST without preprocessor, and compared this model with 3DNS. The proposed MRD method has more performance of recognition rate and more stable system for distortion of input pattern than 3DNS.

• Membrane Journal
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• v.34 no.1
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• pp.58-69
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• 2024

Reverse electrodialysis (RED) is an electro-membrane process employing ion-exchange membranes (IEMs) that can harvest electric energy from the concentration difference between seawater and river water. Multivalent ions contained in seawater and river water bind strongly to the fixed charge groups of the IEM, causing high resistance and reducing open-circuit voltage and power density through uphill transport. In this study, a pore-filled anion-exchange membrane (PFAEM) with excellent monovalent ion selectivity and electrochemical properties was fabricated and characterized for RED application. The monovalent ion selectivity of the prepared membrane was 3.65, which was superior to a commercial membrane (ASE, Astom Corp.) with a selectivity of 1.27 under the same conditions. Additionally, the prepared membrane showed excellent electrochemical properties, including low electrical resistance compared to ASE. As a result of evaluating RED performance under seawater of 0.459 M NaCl/0.0510 M Na₂SO₄ and river water of 0.0153 M NaCl/0.0017 M Na₂SO₄, the maximum power density of 1.80 W/m² was obtained by applying the prepared membrane, which is a 40.6% improved output performance compared to the ASE membrane.

• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.1-6
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• 2024

An easy approach to replacing older diesel engines is to replace them with gas engines using fuels such as CNG or LPG. However, fuels such as LPG have not been applied to large gas engines in many cases, so it is not easy to predict the performance of gas engines based on CNG fuel. Accordingly, in this study, we applied LPG fuel to a CNG-based large gas engine and examined the performance and emission characteristics. In particular, the results were confirmed through tests to see how effective EGR, which is widely used for NOx reduction, is applied. As a result, in the case of LPG, even though the operating conditions were secured to a level that excludes serious knocking, mild knocking at high loads was still found to be more frequent than CNG. However, it was possible to secure an output level similar to CNG in the high-speed range. Efficiency was higher due to a faster combustion speed than CNG, and it was confirmed that it was possible to simultaneously reduce NOx and the frequency of mild knocking through the application of EGR.

• Journal of the HCI Society of Korea
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• v.12 no.2
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• pp.21-29
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• 2017

While the second and the third industrial revolutions made it possible a few standardized designs to be extracted and produced in large quantities, the recent development of the 3D printing technology allowed many individuals to reflect their unique personal characteristics on their creative works and produce them in large quantities-i.e., personally customized designs and mass production of various designs. However, for the customized designs and the mass production of various designs through the 3D printing technology, the individuals should use a 3D modeling software and the supporting features of the software can significantly affect the type and shape of a creative work. In this study, we surveyed the individuals who design the creative works using 3D printers about the type of software that they use and the type of creative works that they design using the software, to propose a possible direction of new software that supports their activities. To do this, we first surveyed sixty members of the OpenCreators, which is the largest 3D printing creator community in South Korea, about the 3D modelling Software that they use for their 3D printing creations, the best 3D modelling software for the 3D printing, and the type of frequently printing creation using the best 3D modelling software. We then analysed the response results. As a result, we found that most of 3D printing creators in South Korea use Rhino and 123D Design. More specifically, the Rhino was being widely used by the people in the 3D printing industry to print prototypes, samples, and mock-ups, while the 123D Design was being mainly used for general purposes such as educational tools, accessories, and home interior accessories. Therefore, we believe it is necessary to develop the software in two separated categories, i.e. for the business, like the Rhino, and for the beginners, and educational and personal purposes, like the 123D Design. Finally, we stressed and proposed the necessity to support individual creators by developing an industry-specific 3D modeling software.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.153-163
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• 2017

The objective of this study is to enhance the model's speed of estimating weather variables (e.g., minimum/maximum temperature, sunshine hour, PRISM (Parameter-elevation Regression on Independent Slopes Model) based precipitation), which are applied to the Agrometeorological Early Warning System (http://www.agmet.kr). The current process of weather estimation is operated on high-performance multi-core CPUs that have 8 physical cores and 16 logical threads. Nonetheless, the server is not even dedicated to the handling of a single county, indicating that very high overhead is involved in calculating the 10 counties of the Seomjin River Basin. In order to reduce such overhead, several cache and parallelization techniques were used to measure the performance and to check the applicability. Results are as follows: (1) for simple calculations such as Growing Degree Days accumulation, the time required for Input and Output (I/O) is significantly greater than that for calculation, suggesting the need of a technique which reduces disk I/O bottlenecks; (2) when there are many I/O, it is advantageous to distribute them on several servers. However, each server must have a cache for input data so that it does not compete for the same resource; and (3) GPU-based parallel processing method is most suitable for models such as PRISM with large computation loads.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.123-130
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• 1991

A docking intraoperative electron beam applicator system, which is easily docking in the collimator for a linear accelerator after setting a sterilized transparent cone on the tumor bearing area in the operation room, has been designed to optimize dose distribution and to improve the efficiency of radiation treatment method with linear accelerator. This applicator system consisted of collimator holder with shielded metals and docking cone with transparent acrylic cylinder, A number of technical innovations have been used in the design of this system, this dooking cone gives a improving latral dose coverage at therapeutic volume. The position of $90\%$ isodose curve under suface of 8 cm diameter cone was extended $4\sim7$ mm at 12 MeV electron and the isodose measurements beneath the cone wall showed hot spots as great as $106\%$ for acrylic cone. The leakage radiation dose to tissues outside the cone wall was reduced as $3\sim5\%$ of output dose. A comprehensive set of dosimetric characteristics of the intraoperative radiation therapy applicator system is presented.