• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.257-264
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• 2012

The development of mobile devices and the spread of wireless network help share and exchange information and resources more easily. The bond them to Cloud Computing technology help pay attention to "Mobile Cloud" service, so there have been being a lot of studies on "Mobile Cloud" service. Especially, the important of 'Recommendation Service' which is customized for each user's preference and context has been increasing. In order to provide appropriate recommendation services, it enables to recognize user's current state, analyze the user's profile like user's tendency and preference, and draw the service answering the user's request. Most existing frameworks, however, are not very suitable for mobile devices because they were proposed on the web-based. And other context information except location information among user's context information are not much considered. Therefore, this paper proposed the context-aware framework, which provides more suitable services by using user's context and profile.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.431-440
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• 2021

The purpose of this study was to classify the latent profiles of elementary school teachers' job stress and to explore the effects of the relative variables to determine these classifications. In addition, the differences in the teacher-student relationship and parental involvement in school based on the classification were discussed. Data from 709 elementary school teachers who participated in the 11th wave of the Panel Study on Korean Children in 2018 were analyzed by Latent Profile Analysis (LPA). The findings can be summarized as follows. First, four subgroups could be defined according to the elementary school teachers' job stress: low-level job stress group, mid-level job stress group, mid-level administrative work stress group, and mid-level relationship and guidance stress group. Second, the final education and average time to work were significant determinants of the latent groups. Third, teacher-student conflict and parental involvement in school showed differences between the subgroups. Specifically, the mid-level relationship and guidance stress group reported the highest conflict level with children and the lowest parental involvement in school. These findings suggest promoting relief and preventative training programs for elementary school teachers to overcome various job stress.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.839-850
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• 2014

As the social and financial damages caused by APT attack such as 3.20 cyber terror are increased, the technical solution against APT attack is required. It is, however, difficult to protect APT attack with existing security equipments because the attack use a zero-day malware persistingly. In this paper, we propose a host based anomaly detection method to overcome the limitation of the conventional signature-based intrusion detection system. First, we defined 39 features to identify between normal and abnormal behavior, and then collected 8.7 million feature data set that are occurred during running both malware and normal executable file. Further, each process is represented as 83-dimensional vector that profiles the frequency of appearance of features. the vector also includes the frequency of features generated in the child processes of each process. Therefore, it is possible to represent the whole behavior information of the process while the process is running. In the experimental results which is applying C4.5 decision tree algorithm, we have confirmed 2.0% and 5.8% for the false positive and the false negative, respectively.

• Journal of Digital Convergence
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• v.10 no.1
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• pp.309-315
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• 2012

The dissemination of smartphones is being spread and supplementary services using smartphones are increasing and various as the Mobile network and device are developing rapidly, so smartphones that enables to provide a wide range of services is expected to receive the most attention. It makes users listen to music anytime, anywhere in real-time, use useful applications, and access to Internet to search for information. The service environment is changing on PC into Mobile due to the change of the circumstance mentioned above. these services are done by using just location information rather than other context, and users have to search services and use them. It is essential to have Context-aware technology for personalization recommendation services and the appropriate representation and definition of Context information for context-aware. Ontology is possible to represent knowledge freely and knowledge can be extended by inferring. In addition, design of the ontology model is needed according to the purposes of utilization. This paper used context-aware technologies to implement a user personalization recommendation service. It also defined the context through OWL modeling for user personalization recommendation service and used inference rules and inference engine for context reasoning.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.275-286
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• 2008

Fast File System(FFS) utilizes large disk bandwidth to improve the write performance of large files. One way to improve the performance is to write multiple blocks of a large file at a single disk I/O through the disk bandwidth. However, rather than disk bandwidth, the performance of small file writes is limited by disk access times significantly impacted by disk movements such as disk seek and rotation because FFS writes each of small files at a single disk write. We propose CW-FFS (Co-Writing Fast File System) to improve the write performance of small files by minimizing the disk movements that are needed to write small files to disks. Its key technique called co-writing scheme is to dynamically collect multiple small files named by a given directory and then write them at a single disk I/O to contiguous disk locations. Co-writing several small files at a single disk I/O reduces multiple disk movements that are needed for small file writes to one single disk movement, thus increasing the overall write performance of write-intensive applications. Furthermore, a file allocation scheme is introduced to prevent co-writing scheme from having a negative impact on disk spatial locality of small files named by a given directory. The measurement of our technique implemented in the OpenBSD 4.0 shows that CW-FFS increases the performance of small file writes over FFS in the range from 5 to 35% in the Postmark benchmark.

• Journal of the Korea Society of Computer and Information
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• v.17 no.10
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• pp.11-23
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• 2012

To achieve efficient code size reduction, this paper proposes a new compressed instruction set architecture for the OpenRISC architecture. The new instructions and their corresponding formats are designed by the profiling information of the existing instruction usage. New 16-bit instructions and 32-bit instructions are proposed to compressed the existing 32-bit instructions and instruction sequences, respectively. The proposed instructions can be classified into three types. The first is the new 16-bit instructions for the frequent normal 32-bit instructions such as add, load, store, branch, and jump instructions. The second type is the new 32-bit instructions for the consecutive two load instructions, two store instructions, and 32-bit data mov instructions. Finally, two new 32-bit instructions are proposed to compress function prolog and epilog code, respectively. OpenRISC hardware decoder is extended to support the new instructions. Experiments show that the efficiency of code size reduction improves by an average of 30.4% when compared to the OR1200 instruction set architecture without loss of execution performance.

• School Mathematics
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• v.15 no.1
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• pp.61-75
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• 2013

This study analyzed Korean students' affective characteristics in mathematical learning according to school and sex by Factor Analysis and Cognitive Diagnosis Theory. In numerical affective achievements by Factor Analysis, there are mean differences between schools, i.e. elementary school and secondary school. And there are sexual differences within schools and boys show more positive achievement than girls. By Cognitive Diagnosis Theory, I investigated 6 affective attributes' proportions that students achieved according to school and sex. Middle school students' proportion is highest in self-control and anxiety and the attribute that students achieved most in all school is cognizing mathematical value. Boys show higher proportion in self directivity, interest and confidence than girls, but girls show higher proportion in anxiety than boys. In personal profiles, the proportion of students who achieved 5 attributes except anxiety is highest.

• Convergence Security Journal
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• v.8 no.4
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• pp.105-113
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• 2008

Mobile computing environment is known to be quite difficult to provide user with a stable Quality of Service (QoS) due to vehicle mobility nature. In order to protect the inherent characteristics of wireless network such as low bandwidth and high transmission delay along with the vehicle's mobility, many works are conducted to apply caching and prefetching methods. This paper presents a novel prefetching technique which is based on owner's profile. It is the scheme with the vehicle velocity, the visit frequency and resident time of specific region for vehicle owner's past given period, and the user profile which has owner's personal inclination about a certain place. The proposed scheme shown relatively superior performance in terms of the utilization ratio of prefetched information and the failure ratio of information retrieval than the previous methods.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06c
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• pp.43-48
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• 2010

정보의 수가 급격하게 증가하면서 일반적인 정보 검색은 사용자의 생활 패턴이나 선호도를 전혀 반영하지 않은 결과를 보여준다. 이로 인하여 자신에게 적합한 정보를 제공받는 개인화 서비스에 대한 연구가 활발히 연구되고 있다. 본 논문에서는 개인화 서비스를 위한 선호도 조사의 방법으로 GPS로그 파일을 이용한다. GPS로그는 사용자의 모든 이동에 대한 객관적인 기록이므로 이를 분석하면 개인의 선호도와 숨어 있는 패턴을 발견할 수 있다. GPS로그를 관리하기 위한 방법으로 대용량 이동 객체 분산 컴퓨팅 시스템을 기반인 GALIS를 응용한 GPS로 그 관리 시스템을 제안하며, 프로토타입 구현을 통해 시스템의 효율성을 보인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1093-1096
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• 2003

인터넷 프로토콜들은 RFC(Request For Comments)에 정의되어 있다. 하지만 RFC 는 단순한 권고 사항 일뿐 강제적인 요구사항은 아니다. 그렇기 때문에 RFC 에 정의되어 있는 흐름제어 메커니즘 같은 권고사항을 무시하고 인터넷 프로토콜들을 구현할 수도 있다. 그러나 이렇게 구현된 프로토콜들이 망에 미치는 영향이나, 그것을 제한하기 위한 연구는 아직까지 이루어 지지 않고 있다. 본 논문에서는 RFC 규격을 따르지 않는 TCP와 RFC 규격을 따르는 표준 TCP와의 성능 차이를 비교하였다. 그것을 위하여 리눅스 커널의 TCP 프로토콜을 수정하여 흐름제어를 하지 않는 서로 다른 6개의 항목을 만들고, 표준 TCP와의 성능을 비교하였다. 그 결과, 목적지가 근거리인 경우 정상적인 TCP와 본 연구에서 수정된 TCP 간의 파일 전송 시간의 차이는 크게 나지 않았다. 하지만, 원거리에 있는 목적지로 웹 페이지 정도의 작은 파일을 전송할 경우, 흐름제어 메커니즘 중 저속 출발(slow start)을 적용하지 않았을 때는 전송 시간에서 매우 큰 차이를 나타냈다.