• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.305-312
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• 2014

Purpose : The purpose of this study is to analyze the mechanical and leaf speed accuracy of the dynamic multileaf collimator (DMLC) and determine the appropriate period of quality assurance (QA). Materials and Methods : The quality assurance of the DMLC equipped with Millennium 120 leaves has been performed total 92 times from January 2012 to June 2014. The the accuracy of leaf position and isocenter coincidence for MLC were checked using the graph paper and Gafchromic EBT film, respectively. The stability of leaf speed was verified using a test file requiring the leaves to reach maximum leaf speed during the gantry rotation. At the end of every leaf speed QA, dynamic dynalog files created by MLC controller were analyzed using dynalog file viewer software. This file concludes the information about the planned versus actual position for all leaves and provides error RMS (root-mean square) for individual leaf deviations and error histogram for all leaf deviations. In this study, the data obtained from the leaf speed QA were used to screen the performance degradation of leaf speed and determine the need for motor replacement. Results : The leaf position accuracy and isocenteric coincidence of MLC was observed within a tolerance range recommanded from TG-142 reports. Total number of motor replacement were 56 motors over whole QA period. For all motors replaced from QA, gradually increased patterns of error RMS values were much more than suddenly increased patterns of error RMS values. Average error RMS values of gradually and suddenly increased patterns were 0.298 cm and 0.273 cm, respectively. However, The average error RMS values were within 0.35 cm recommended by the vendor, motors were replaced according to the criteria of no counts with misplacement > 1 cm. On average, motor replacement for gradually increased patterns of error RMS values 22 days. 28 motors were replaced regardless of the leaf speed QA. Conclusion : This study performed the periodic MLC QA for analyzing the mechanical and leaf speed accuracy of the dynamic multileaf collimator (DMLC). The leaf position accuracy and isocenteric coincidence showed whthin of MLC evaluation is observed within the tolerance value recommanded by TG-142 report. Based on the result obtained from leaf speed QA, we have concluded that QA protocol of leaf speed for DMLC was performed at least bimonthly in order to screen the performance of leaf speed. The periodic QA protocol can help to ensure for delivering accurate IMRT treatment to patients maintaining the performance of leaf speed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.8
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• pp.22-30
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• 2009

Due to high levels of integration and complexity, the Network-on-Chip (NoC) approach has emerged as a new design paradigm to overcome on-chip communication issues and data bandwidth limits in conventional SoC(System-on-Chip) design. In particular, exponentially growing of energy consumption caused by high frequency, synchronization and distributing a single global clock signal throughout the chip have become major design bottlenecks. To deal with these issues, a globally asynchronous, locally synchronous (GALS) design combined with low power techniques is considered. Such a design style fits nicely with the concept of voltage-frequency-islands (VFI) which has been recently introduced for achieving fine-grain system-level power management. In this paper, we propose an efficient design methodology that minimizes energy consumption by VFI partitioning on an NoC architecture as well as assigning supply and threshold voltage levels to each VFI. The proposed algorithm which find VFI and appropriate core (or processing element) supply voltage consists of traffic-aware core graph partitioning, communication contention delay-aware tile mapping, power variation-aware core dynamic voltage scaling (DVS), power efficient VFI merging and voltage update on the VFIs Simulation results show that average 10.3% improvement in energy consumption compared to other existing works.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.657-667
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• 2020

The Android framework allows apps to take full advantage of personal information through granting single permission, and does not determine whether the data being leaked is actual personal information. To solve these problems, we propose a tool with static/dynamic analysis. The tool analyzes the Source and Sink used by the target app, to provide users with information on what personal information it used. To achieve this, we extracted the Source and Sink through Control Flow Graph and make sure that it leaks the user's privacy when there is a Source-to-Sink flow. We also used the sensitive permission information provided by Google to obtain information from the sensitive API corresponding to Source and Sink. Finally, our dynamic analysis tool runs the app and hooks information from each sensitive API. In the hooked data, we got information about whether user's personal information is leaked through this app, and delivered to user. In this process, an automated Source/Sink classification model was applied to collect latest Source/Sink information, and the we categorized latest release version of Android(9.0) with 88.5% accuracy. We evaluated our tool on 2,802 APKs, and found 850 APKs that leak personal information.

• The Journal of Korean society of community based occupational therapy
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• v.5 no.2
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• pp.31-42
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• 2015

Objective : The aim of this study is to prove the effects of mental practice in balance ability of elderly population, and to investigate the possibility of application as an effective intervention method for fall prevention. Methods : This study provided mental practice to 3 subjects over 65 years old who have experienced fall, but do not have cognitive dysfunctions and independent in gait without any use of assistive devices from July to October, 2013. Within the individual case study, 4 sessions of initial baseline process (A), 5 sessions of mental practice (B), 4 sessions of re-initial baseline process (A') were proceeded using ABA design. Independent variable used mental practice for enhancing balance ability and fall efficacy in elderly population, and dependent variable were Berg Balance Scale (BBS) to find out the change in overall balance ability, Fall Efficacy Scale (FES) to see the change in fall efficacy, One-Leg Standing test(OLS), and Timed Up and Go Test (TUG) to determine the changes in both static and dynamic balance. Analysis of the results were provided via mean value and graph. Results : After the application of mental practice method, all of the subjects have shown increase in fall efficacy baseline values, and in addition, overall balance ability and both static and dynamic balances either increased or maintained. Conclusion : This study demonstrated that mental practice has positive effects on fall efficacy improvement and maintenance in elderly, thereby suggesting mental practice for fall prevention in elderly populations.

• Journal of Service Research and Studies
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• v.14 no.2
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• pp.18-36
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• 2024

As interest in ESG has been increased, it is easy to find papers that empirically study that a company's ESG activities have a positive impact on the company's performance. However, research on what ESG activities companies should actually engage in is relatively lacking. Accordingly, this study systematically classifies ESG activities of companies and seeks to provide insight to companies seeking to plan new ESG activities. This study analyzes how Chinese manufacturing companies perform ESG activities based on their dynamic capabilities in the global economy and how they differ in their activities. This study used the ESG annual reports of 151 Chinese manufacturing listed companies on the Shanghai & Shenzhen Stock Exchange and ESG indicators of China Securities Index Company (CSI) as data. This study focused on the following three research questions. The first is to determine whether there are any differences in ESG activities between companies with high ESG scores (TOP-25) and companies with low ESG scores (BOT-25), and the second is to determine whether there are any changes in ESG activities over a 10-year period (2010-2019), focusing only on companies with high ESG scores. The results showed that there was a significant difference in ESG activities between high and low ESG scorers, while tracking the year-to-year change in activities of the top-25 companies did not show any difference in ESG activities. In the third study, social network analysis was conducted on the keywords of E/S/G. Through the co-concurrence matrix technique, we visualized the ESG activities of companies in a four-quadrant graph and set the direction for ESG activities based on this.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.102-116
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• 2006

Electronic catalogs (or e-catalogs) hold information about the goods and services offered or requested by the participants, and consequently, form the basis of an e-commerce transaction. Catalog management is complicated by a number of factors and product classification is at the core of these issues. Classification hierarchy is used for spend analysis, custom3 regulation, and product identification. Classification is the foundation on which product databases are designed, and plays a central role in almost all aspects of management and use of product information. However, product classification has received little formal treatment in terms of underlying model, operations, and semantics. We believe that the lack of a logical model for classification Introduces a number of problems not only for the classification itself but also for the product database in general. It needs to meet diverse user views to support efficient and convenient use of product information. It needs to be changed and evolved very often without breaking consistency in the cases of introduction of new products, extinction of existing products, class reorganization, and class specialization. It also needs to be merged and mapped with other classification schemes without information loss when B2B transactions occur. For these requirements, a classification scheme should be so dynamic that it takes in them within right time and cost. The existing classification schemes widely used today such as UNSPSC and eClass, however, have a lot of limitations to meet these requirements for dynamic features of classification. In this paper, we try to understand what it means to classify products and present how best to represent classification schemes so as to capture the semantics behind the classifications and facilitate mappings between them. Product information implies a plenty of semantics such as class attributes like material, time, place, etc., and integrity constraints. In this paper, we analyze the dynamic features of product databases and the limitation of existing code based classification schemes. And describe the semantic classification model, which satisfies the requirements for dynamic features oi product databases. It provides a means to explicitly and formally express more semantics for product classes and organizes class relationships into a graph. We believe the model proposed in this paper satisfies the requirements and challenges that have been raised by previous works.

• Journal of the Korean Society of Radiology
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• v.12 no.6
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• pp.755-762
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• 2018

The purpose of this study was to compare the FA(faractional anisotropy) and ADC(apparent diffusion coefficient) values, which were derived from diffusion tensor imaging in breast cancer patients. The diffusion gradient used in this study was derived from quantitative diffusion indices using 20 directions(b-value, 0 and $1,000s/mm^2$). Quantitative analysis was analyzed using Pearson's correction and qualitative analysis using for correction coefficients. As a result, $FA_{min}$, $FA_{mean}$ and $FA_{max}$ were $0.098{\pm}0.065$, $0.302{\pm}0.142$ and $0.634{\pm}0.236$, respectively(p > 0.05). The $ADC_{min}$, $ADC_{mean}$ and $ADC_{max}$ were $0.741{\pm}0.403$, $1.095{\pm}0.394$ and $1.530{\pm}0.447$, respectively(p > 0.05). The $FA_{min}$, $FA_{mean}$, and $FA_{max}$ mean values were $0.132{\pm}0.050$, $0.418{\pm}0.094$, and $0.770{\pm}0.164$ for Category 6 and Kinetic Curve Pattern III, respectively. $ADC_{min}$, $ADC_{mean}$, and $ADC_{max}$ were $0.753{\pm}0.189$, $1.120{\pm}0.236$, and $1.615{\pm}0.372$, respectively. Quantitative analysis showed negative correlation between $ADC_{mean}-FA_{mean}$ and $ADC_{max}-FA_{max}$(p = 0.001, 0.003). The qalitative analysis showed ADC 0.628(p = 0.001), FA 0.620(p = 0.001) in the internal evaluations, ADC 0.677(p = 0.001), FA 0.695(p = 0.001) in external evaluations. In conclusion, based on the morphological examination, time to signal intensity graph is the form of wash-out(pattern III) in the dynamic contrast enhance examination, As a result, the $ADC_{mean}$ $1.120{\pm}0.236$ and $FA_{mean}$ values were $0.032{\pm}0.142$ with a negative correlation (Y=1.44-1.12X). Therefore, If we understand the shape of time to signal intensity graph and the relationship between ADC and FA, It will be a criterion for distinguishing malignant diseases in breast cancer.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.4
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• pp.27-34
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• 2011

In this paper, it was presented a design on the dynamic multimedia fingerprinting code for anti-collusion code(ACC) in the protection of multimedia content. Multimedia fingerprinting code for the conventional ACC, is designed with a mathematical method to increase k to k+1 by transform from BIBD's an incidence matrix to a complement matrix. A codevector of the complement matrix is allowanced fingerprinting code to a user' authority and embedded into a content. In the proposed algorithm, the feature points were drawing from a content which user bought, with based on these to design the dynamical multimedia fingerprinting code. The candidate codes of ACC which satisfied BIBD's v and k+1 condition is registered in the codebook, and then a matrix is generated(Below that it calls "Rhee matrix") with ${\lambda}+1$ condition. In the experimental results, the codevector of Rhee matrix based on a feature point of the content is generated to exist k in the confidence interval at the significance level ($1-{\alpha}$). Euclidean distances between row and row and column and column each other of Rhee matrix is working out same k value as like the compliment matrices based on BIBD and Graph. Moreover, first row and column of Rhee matrix are an initial firing vector and to be a forensic mark of content protection. Because of the connection of the rest codevectors is reported in the codebook, when trace a colluded code, it isn't necessity to solve a correlation coefficient between original fingerprinting code and the colluded code but only search the codebook then a trace of the colluder is easy. Thus, the generated Rhee matrix in this paper has an excellent robustness and fidelity more than the mathematically generated matrix based on BIBD as ACC.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.331-340
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• 2016

Wheel load, design velocity, traffic amount (MGT), stiffness and thickness of sub-layers of asphalt concrete track are selected as performance design parameters in this study. A pseudo-static wheel load computed considering the dynamic amplification factor (DAF) based on the design velocity of the KTX was applied to the top of asphalt concrete track for full three dimensional structural analysis using the ABAQUS program. Tensile strains at the bottom of the asphalt concrete layer and vertical strains at the top of the subgrade were computed from the structural FEA with different combinations of performance parameter values for one asphalt concrete track section. Utilizing the computed structural analysis results such as the tensile strains and the vertical strains, it was possible to develop design graphs to investigate proper track sections for different combination of the performance parameters including wheel load, design velocity, traffic amount(MGT), stiffness and thickness of asphalt concrete layers for any given design life. By analyzing the proposed design graphs for asphalt concrete track, it was possible to propose simple design tables that can be used by engineers for the effective and fast design of track.

• Journal of Educational Research in Mathematics
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• v.27 no.2
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• pp.157-170
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• 2017

Mathematics was the main domain of PISA 2012, and both paper-based and computer-based assessment of mathematics (CBAM) were conducted. PISA 2012 was the first large-scale computer-based mathematics assessment in Korea, and it is meaningful in that it evaluated students' mathematical literacy in problem situations using dynamic geometry, graph, and spreadsheet. Although Korea ranked third in CBAM, the use of ICT in mathematics lessons appeared to be low. On the other hand, this study focused on Singapore, which ranked first in CBAM. The Singapore Ministry of Education developed online programs such as AlgeTools and AlgeDisc, and implemented the programs in classes by specifying them in mathematics curriculum and textbooks. Thus, this study investigated influential factors on computer-based assessment of mathematics by comparing the results of Korea and Singapore, and aimed to provide meaningful evidence on the direction of Korea's ICT-based mathematics education. The results showed that ICT use at home for school related tasks, attitudes towards computers as a tool for school learning, and openness and perseverance of problem solving were positively associated with computer-based mathematics performance, whereas the use of ICT in mathematics class by teacher demonstration was negatively related. Efforts are needed to improve computer use and enhance teaching techniques related to ICT use in Korean math classes. Future research is recommended to examine how effectively teachers use ICT in mathematics class in Singapore.