• Journal of Korean Society of Forest Science
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• v.107 no.1
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• pp.59-70
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• 2018

The objective of this study was to develop erosion control dam for preventing disaster in consideration of characteristics of forested catchment near urban area, and to assess its stability and functionality to see its practicability in the field. Two types of hybrid erosion control dams were developed including debris flow prevention dam by using pillar and float board screen type and debris flow control dam by using groyne. Also, review about their static (sliding, overturning, bearing capacity) and dynamic (member force) stability was carried out. According to the result, most of the assessed items met standard safety level although there were some cases where assessed items were short of stability criteria against impact. Also, after miniature flume experiments based on the developed erosion control dam to prove structure function (material catch, deposit), it turned out the dam decreased flow sediment amount and velocity while increasing sediment-capturing capacity by 3.5 times on average compared to the one controlled without erosion control dam. When function of erosion control dam for forested catchment near urban area is quantified based on future flume experiments in a variety of conditions, the dams can be practically used in the urban area, contribution to effectively reducing debris flow damage.

• Communications of Mathematical Education
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• v.27 no.4
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• pp.473-486
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• 2013

This study examines the learning styles of freshmen enrolled in a college of science and engineering, and analyses the relationship between learning styles and academic achievement in mathematics to provide basic data for the teaching-learning methods, which are more suitable to learning styles of students. For the purpose of this research, a reliability analysis of Kolb's LSI is applied to 282 freshmen enrolled in a college of science and engineering of the medium-sized university. The outcomes of this survey are followings. Firstly, students hold higher positions in the order of converger, assimilator, accommodator, diverger among 4 learning styles. Secondly, while there is a positive corelation between abstract conceptualization[AC] and academic achievement, there is a negative corelation between concrete experience[CE] and academic achievement. Thirdly, as for academic achievement in mathematics, converger is superior to assimilator and accommodator. Finally, the correlation between learning styles and academic achievement is different by demographic characteristics. Based on these results, this study suggests the necessity for various teaching-learning strategies, which are adjusted to both academic characteristics of mathematics and learning styles. Also, the need for teaching methods, which help students to develop effectively four learning cycles, is proposed.

• Fire Science and Engineering
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• v.33 no.3
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• pp.154-165
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• 2019

This study was conducted to investigate whether ego - resilience plays a mediating role in the relationship between adult attachment and job stress of fire officers, and to derive implications for job stress reduction of fire officers. A questionnaire survey was conducted for 480 fire officers working in Seoul and Gyeonggi - do, and correlation analysis and regression analysis were conducted using SPSS 21.0. The results showed that there was a negative correlation between instability attachment and job stress in adult attachment, negative correlation between instability attachment and ego - resilience in adult attachment, and negative correlation between ego - resilience and job stress. Adult attachment and ego - The results showed that there was a statistically significant effect on stress. Ego - resilience was found to full mediate the effect of anxiety of adult attachment on job stress and to partial mediate the effect of avoidance on job stress. This study suggests the need to develop a program that can improve ego - resilience considering the importance of ego - resilience and the occupational characteristics of fire officer. This means that the psychological and psychological factors of the individual should also be considered in order to reduce the level of job stress of the fire service personnel.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.188-198
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• 2013

In order to increase its performance, NAND flash memory-based storage is composed of data buses that are shared by a number of flash memories and uses a parallel technique that can carry out multiple flash memory operations simultaneously. Since the storage performance is strongly influenced by the performance of each data bus, it is important to improve the utilization of the bus by ensuring effective scheduling of operations by the storage controller. However, this is difficult because of dynamic changes in buses due to the unique characteristics of each operation with different timing, cost, and usage by each bus. Furthermore, the scheduling technique for increasing bus utilization may cause unanticipated operation delay and wastage of storage resource. In this study, we suggest various dynamic operation scheduling techniques that consider data bus performance and storage resource efficiency. The proposed techniques divide each operation into three different stages and schedule each stage depending on the characteristics of the operation and the dynamic status of the data bus. We applied the suggested techniques to the controller and verified them on the FPGA platform, and found that program operation decreased by 1.9% in comparison to that achieved by a static scheduling technique, and bus utilization and throughput was approximately 4-7% and 4-19% higher, respectively.

• Korean Security Journal
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• no.19
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• pp.139-163
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• 2009

The purpose of this study is to build up the expert system with more subdivided qualifications and improved qualities with the development of the security industry. And also it is to analyze a survey measuring how satisfied they are with curriculum, teaching faculty, educational administration, facilities among 439 private guards completing a course in Korea private guard educational institution and registered in the National Police Agency in Seoul, Gyeonggi, Chungcheong, Gyeongsang, Jeolla province. For this, SPSS(Statistical Packages for Social Science) 15.0 Version was adapted to analyze and other analysis methods used for this study are like these: frequency, reliability analysis, regressive analysis, moderated multiple regression, post hoc test for categorizing the performance changes, looking into the characteristics, examining closely job performance, intention to quit one's job, and inquiring into the influence how satisfaction measurement at education training satisfaction makes on carrying out one's job. Firstly, The Effect Satisfaction at The Program has on Performing One's Duty With respect to job performance, curriculum, educational administration, teaching abilities have positive influences on it. On the other hand, with respect to quitting one's job, curriculum just makes positive effects on leaving one's work statistically. It indicates that systematic and effective curriculum, administration, teaching faculty or contents with high quality rather than just education facilities would make the task performance excellent and satisfaction at the program well in regards to making effects on the task performance. Secondly, The Effect Satisfaction at The Program has on Performing One's Duty with Social Supports Despite being the fact that statistically any strong correlation between curriculum and social supports, one between education facilities and social supports, one between teaching abilities and social supports, and one between educational administration and social supports do not have influences on carrying out job performance, it turns out that satisfaction at the program and social supports make positive effects on performing one's task. In conclusion, the entire social system and support need to be improved and some institutions appropriate for satisfaction at the program should be established as soon as possible.

• Journal of KIISE:Databases
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• v.35 no.5
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• pp.447-458
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• 2008

In this paper, we address an efficient processing scheme for k-nearest neighbor queries to retrieve k static objects in road network databases. Existing methods cannot expect a query processing speed-up by index structures in road network databases, since it is impossible to build an index by the network distance, which cannot meet the triangular inequality requirement, essential for index creation, but only possible in a totally ordered set. Thus, these previous methods suffer from a serious performance degradation in query processing. Another method using pre-computed network distances also suffers from a serious storage overhead to maintain a huge amount of pre-computed network distances. To solve these performance and storage problems at the same time, this paper proposes a novel approach that creates an index for moving objects by approximating their network distances and efficiently processes k-nearest neighbor queries by means of the approximate index. For this approach, we proposed a systematic way of mapping each moving object on a road network into the corresponding absolute position in the m-dimensional space. To meet the triangular inequality this paper proposes a new notion of average network distance, and uses FastMap to map moving objects to their corresponding points in the m-dimensional space. After then, we present an approximate indexing algorithm to build an R*-tree, a multidimensional index, on the m-dimensional points of moving objects. The proposed scheme presents a query processing algorithm capable of efficiently evaluating k-nearest neighbor queries by finding k-nearest points (i.e., k-nearest moving objects) from the m-dimensional index. Finally, a variety of extensive experiments verifies the performance enhancement of the proposed approach by performing especially for the real-life road network databases.

• Journal of Korea Multimedia Society
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• v.13 no.3
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• pp.417-429
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• 2010

Though background subtraction has been widely studied for last decades, it is still a poorly solved problem especially when it meets real environments. In this paper, we first address some common problems for background subtraction that occur in real environments and then those problems are resolved by improving an existing GMM-based background modeling method. First, to achieve low computations, fixed point operations are used. Because background model usually does not require high precision of variables, we can reduce the computation time while maintaining its accuracy by adopting fixed point operations rather than floating point operations. Secondly, to avoid erroneous backgrounds that are induced by high pedestrian traffic, static levels of pixels are examined using shot-time statistics of pixel history. By using a lower learning rate for non-static pixels, we can preserve valid backgrounds even for busy scenes where foregrounds dominate. Finally, to adapt rapid illumination changes, we estimated the intensity change between two consecutive frames as a linear transform and compensated learned background models according to the estimated transform. By applying the fixed point operation to existing GMM-based method, it was able to reduce the computation time to about 30% of the original processing time. Also, experiments on a real video with high pedestrian traffic showed that our proposed method improves the previous background modeling methods by 20% in detection rate and 5~10% in false alarm rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.200-207
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• 2016

The automotive seat is an important component that moves in sync with the driver and is actively being developed with various new functions. The aim of this work is to develop a lightweight seat cushion extension module using a lightweight material. To this end, a structural strength analysis, vertical strength test, and durability test were conducted. In the structural analysis, the maximum value of deformation under vertical load was 4.98 mm at the front of the upper panel. The maximum stress was approximately 105 MPa, which occurred at the point of contact between the upper and lower panels of the module. The vertical strength test showed a maximum vertical deformation of 5.31 mm under a vertical load, which differed from the analysis results by approximately 6.45%. The structural safety of the product was verified by the fact that it showed no harmful deformation or damage during operation after the vertical strength test and a durability test for 20,000 cycles. Furthermore, the use of engineering plastics made it possible to reduce the weight by approximately 30% compared to existing products. The lack of damage after tests verified the passenger safety, strength, and rigidity of the product. The results are expected to be applied for improving environmental and fuel efficiency regulations and preventing accidents due to driver fatigue. The applications of this module could be expanded various types of vehicles, as well as other industries in which eco-friendly and lightweight materials are used.

• The Journal of the Korea Contents Association
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• v.11 no.3
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• pp.281-292
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• 2011

In this study, for examining an effect of lower limbs' muscle activity on balance capability when applying sprinter pattern among the PNF, the experiment was conducted as followed. Under the object of 24 people diagnosed by hemiplegia, they were divided into control group and experimental group and the experiment was conducted on the experimental group, three times per a week for six weeks. Experimental group received Sprinter pattern of combined PNF upper extremity and lower extremity pattern. For the lower limbs' muscle activity, effective values of Vastus medialis laterails, medial lateral hamstrings, lateral gastrocnemius' action potential were analyzed. The balance ability tests was conducted with FICSIT-4, FSST and MTD-Balance system. For the significance test of control group and experimental group for measuring time by exercise application method, two-way repeated measure ANOVA was conducted and for the significance test among the groups by each measuring time, independent t-test was conducted. Also, for examining the correlation among the measuring item, pearson correlation was used for the analysis. As the result, the application of sprinter pattern increased muscle activity of lower limbs in paretic side and improve static and dynamic balance ability effectively. Therefore, it will be necessary to develop new intervention by combining active application of the therapeutic intervention program for lower limbs' effective muscle mobilizing in paretic side with various exercising patterns.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.6
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• pp.545-550
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• 2013

In pattern recognition field, data classification is an essential process for extracting meaningful information from data. Adaptive boosting algorithm, known as AdaBoost algorithm, is a kind of improved boosting algorithm for applying to real data analysis. It consists of weak classifiers, such as random guessing or random forest, which performance is slightly more than 50% and weights for combining the classifiers. And a strong classifier is created with the weak classifiers and the weights. In this paper, a research is performed using AdaBoost algorithm for detecting chaff echo which has similar characteristics to precipitation echo and interrupts weather forecasting. The entire process for implementing chaff echo classifier starts spatial and temporal clustering based on similarity with weather radar data. With them, learning data set is prepared that separated chaff echo and non-chaff echo, and the AdaBoost classifier is generated as a result. For verifying the classifier, actual chaff echo appearance case is applied, and it is confirmed that the classifier can distinguish chaff echo efficiently.