• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.553-556
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• 2004

복합 스케줄링 작업은 탐색 공간이 방대하므로 단순 스케줄링을 통한 방법으로는 최적해를 찾는 것은 쉽지 않다. 복합 스케줄링 문제를 해결하는 기법들 중에서 사용자의 선호도를 고려한 기법은 제약만족문제와 객체지향개념을 스케줄링에 적용하여 복합 스케줄링 문제를 해결하고자 하였다. 본 논문은 사용자의 선호도를 고려한 기법을 예약 문제에 적용하여 예약 시에 일어날 수 있는 문제점들을 해결하고자 하였다. 특히 고객들의 만족도를 높이기 위해서 고객들의 선호도를 고려하여 스케줄링을 한다. 고객의 선호도를 고려한 예약 스케줄링 기법은 객체 지향 개념을 기반으로 하여 각 객체들이 사건들을 가지고서, 이 사건들을 주어진 제약들에 만족하도록 보드에 배정하는 기법이다. 각 객체들은 전체적인 만족도를 고려하면서 그 객체들의 우선순위에 따라서 자원을 배정하고, 자원에 대한 객체의 선호도 차이를 가질 수 있게 하였다. 예약 스케줄링을 할 때 제약은 전역제약과 지역제약으로 구성된다. 보드에 대한 정의와 모든 사건들에 대한 정보를 전역제약으로 사용하고, 각 객체가 가지는 보드의 슬롯들에 대한 선호도를 지역 제약으로 사용한다. 사건의 배정을 실패하지 않고 백크래킹을 최소화하도록 앞을 보는(look-ahead) 백트래킹 기법을 사용하여 전체 객체들의 만족도를 높였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.835-836
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• 2009

모니터링은 시스템의 문제 상황을 판단하기 위해서 아주 중요한 요소이다. 응답시간과 같은 외부적인 요인들은 쉽게 모니터링이 가능하지만, 시스템의 동작 상태와 같은 내부의 상태를 모니터링하도록 개발하는 것은 많은 노력이 든다. 본 논문에서는 UML을 이용하여 HB(Heart-Beat) 모니터링할 수 있는 모니터링 코드를 생성하는 방법을 제안한다. 본 방법론에서는 AOP를 이용한 모니터링 코드를 생성하여 기존 시스템의 코드를 수정하지 않고도 모니터링 기능을 추가할 수 있으며, UML을 기반으로 큰 노력 없이 자동으로 모니터링 코드 생성이 가능하다.

• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1429-1444
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• 2016

We suggest a monitoring procedure to detect changes in the mean of the stochastic process. The monitoring procedure is based on penalized least squares estimates. Unlike the fluctuation (FL) monitoring, we use the numbers of nonzero estimates not the fluctuations of sequential parameter estimates. We investigate the behavior of the proposed monitoring procedure by means of a simulation study and compare its performance with CUSUM monitoring.

• The Journal of the Korea Contents Association
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• v.6 no.9
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• pp.28-41
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• 2006

Recently, Baruah et.al. proposed an optimal Pfair scheduling algorithm in the hard real-time multiprocessor environments, and several variants of it were presented. All these algorithms assume the fixed unit quantum size, and this assumption has two problems in the mode change environments. If the quantum size is too large, it results in the scheduling failure due to the decreased processor utilization. If it is too small, it increases the frequency of scheduling points, and it incurs the task switching overheads. In this paper, we propose several methods that determine the maximum quantum size dynamically such that the task set can be scheduled in the mode change environments.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1875-1878
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• 2009

최근 하천의 치수, 이수적인 기능뿐만 아니라 자연 친화적인 하천을 조성하려는 노력들을 많이 하고 있다. 하지만 복원사업을 위한 설계 및 평가 기준이 명확히 정립되지 못하여 치수안전성 및 하도안정성에 대한 평가가 이루어지지 못하고 있다. 따라서 복원 기법에 대한 복원 전, 중, 후의 모니터링을 통하여 복원 후의 하천 변화를 예측하고, 실제 사업 시행 후 장기간의 모니터링을 통해서 적용 기법이 안정화 되어가는지에 대한 평가가 반드시 필요하다. 이에 본 연구에서는 2001년에 시작하여 2006년 12월에 복원 사업이 완료된 오산천 하천환경 정비사업에 대한 수리학적 모니터링을 수행하여 복원 후에 대한 하천 변화를 살펴보았다. 오산천의 경우 정비사업에 따른 공사 전, 중, 후에 대한 모니터링이 과거에 수행되었지만 단기간의 모니터링이었기 때문에 하천의 안정화 과정을 확인하기에는 많이 부족하였다. 따라서 본 연구에서는 과거 모니터링 자료를 기초로 하여 하천복원의 목적에 부합하도록 하천이 적응관리 되고 있는지 여부를 확인하기 위해 수리학적 모니터링을 하였다. 수리학 적 모니터링은 과거 수리 수문 자료를 바탕으로 호안 변화에 따른 하상 및 하도 변화와 하천 구조물의 영향분석에 초점을 맞추어 수행하였다. 본 연구에서 검토된 사항을 바탕으로 향후 하천의 수리학적 모니터링을 위한 지표 마련에 도움이 될 것으로 기대된다.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.3
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• pp.47-59
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• 2007

IPv4 NAT, which often used in households or under SOHO environments, is one of the factors that delays IPv6 propagation. As IPv4 NAT does not operate properly under the transition mechanism like ISATAP or 6to4 that acts as IPv6-in-IPv4 tunneling type, Microsoft proposed Teredo in order to resolve this issue. However, tunneling transition mechanism like Teredo has a security problem. That is, being tunneled packets have dual IP headers; general firewall systems apply the filtering rules only to the outer header but not inner header when these packets pass the firewall. Furthermore, attacks using unregistered server and relay can take place in Teredo. To resolve these problems, we propose a new packet filtering mechanism exclusively for Teredo. The proposed packet filtering mechanism was designed and implemented by using Linux Netfilter and ip6tables. Through functional and experimental performance tests, this packet filtering system was found operating properly and solving the Teredo packet filtering problems without serious performance degradation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.6
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• pp.34-51
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• 2008

Today, the Internet is a part of our life. For that reason, we regard revealing characteristics of Internet traffic as an important research theme. However, Internet traffic cannot be easily manipulated because it usually occupy huge capacity. This problem is a serious obstacle to analyze Internet traffic. Many researchers use various sampling techniques to reduce capacity of Internet traffic. In this paper, we compare several famous sampling techniques, and propose efficient sampling scheme. We chose some sampling techniques such as Systematic Sampling, Simple Random Sampling and Stratified Sampling with some sampling intensities such as 1/10, 1/100 and 1/1000. Our observation focused on Traffic Volume, Entropy Analysis and Packet Size Analysis. Both the simple random sampling and the count-based systematic sampling is proper to general case. On the other hand, time-based systematic sampling exhibits relatively bad results. The stratified sampling on Transport Layer Protocols, e.g.. TCP, UDP and so on, shows superior results. Our analysis results suggest that efficient sampling techniques satisfactorily maintain variation of traffic stream according to time change. The entropy analysis endures various sampling techniques well and fits detecting anomalous traffic. We found that a traffic volume diminishment caused by bottleneck could induce wrong results on the entropy analysis. We discovered that Packet Size Distribution perfectly tolerate any packet sampling techniques and intensities.

• Journal of the Korean Chemical Society
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• v.64 no.6
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• pp.401-415
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• 2020

The purpose of this study was to investigate the factors that affect the maintenance of the effect of mentoring for beginning science teachers. Mentee teachers for this study were ten mentee teachers who took part in the collaborative mentoring from 2014 to 2018. For this study, the videos of the first and fifth classes submitted during the mentoring program, mentors and mentees' journals, the videos of the classes recorded in 2019, questionnaires about reflection on the mentoring program, and interview materials were collected and analyzed. The result of this study is as follows. First, the reflective thinking was sustained after the mentoring program, and this played a crucial role in maintaining the effects of the mentoring. The group that showed the improvement of RTOP score had reflective thinking and made reflective practice on their teaching. Most participants in the group created the classes of constructivism based on self-reflection on their classes. However, no positive changes in the classes occurred to mentee teachers who couldn't have reflective thinking. Second, reflective practices during the mentoring program exerted a strong influence on the teaching method of mentee teachers. The group of the improvement in RTOP score strived to apply student-centered model of instruction to their classes. It was showed that most mentee teachers in the group kept applying the student-centered model to their classes after the mentoring was completed. These results indicate reflective thinking and reflective practice are crucial factors to the effect of the mentoring and its maintenance.

• Journal of the Korean Chemical Society
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• v.61 no.5
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• pp.251-262
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• 2017

The purpose of this study was to investigate characteristics of interaction in mentoring conversations and to examine how the interaction features change as mentor teachers have more mentoring experiences. Participants of this study were three mentor who have over 17 years' teaching experience and six beginning science teachers. For this study, one-to-one mentoring dialogue recordings and transcripts were collected and the dialogues were analyzed by utilizing an analytical framework of interaction. the result of analyzing characteristics of mentors' interaction shows that mentors used simple questions and support the most when they started mentoring conversation. the change of characteristics of mentor's interactions indicates three mentors tended to use more thought-provoking questions in the $2^{nd}$ year mentoring than in the $1^{st}$ year and as a result of it mentee's reflection and reflective practices were increased. Through mentors' interview, the mentors could have the opportunity to reflect their own mentoring and this means mentors' self reflection was provoked by means of the mentoring program.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8B
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• pp.721-729
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• 2004

In this paper, we applied a group scheduling algorithm to core nodes in an optical burst switching (OBS) network and measured its performance by simulation. For the case of core nodes with multi-channel input/output ports, performance of the group scheduling has been compared to that of the immediate scheduling. Since the group scheduling has a characteristic of scheduling a group of bursts simultaneously in a time window using information collected from corresponding burst header packets arrived earlier to a core node, simulation results show that the group scheduling outperforms the immediate scheduling in terms of both burst loss probability and channel utilization and the difference gets larger as the load increases. Another node configuration in which wavelength converters are equipped at the output ports has also been considered. In this case, even though both performance metrics of the group scheduling are almost the same as those of the immediate scheduling in the offered load range between 0.1 and 0.9, the group scheduling has lower wavelength conversion rate than the immediate scheduling by at least a factor of seven. This fact leads us to the conclusion that the group scheduling makes it possible to implement more economical OBS core nodes.