• Tunnel and Underground Space
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• v.29 no.5
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• pp.346-355
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• 2019

When evaluating pillar stability in very closely spaced tunnels, a local safety factor (strength/stress ratio) at the minimum width has been widely used. Tension bolts have been frequently applied as reinforcement for the cases where safety factors are less than 1.0 from FEM stress analysis. However, the local safety factor shows a constant value irrespective of the change in pillar width/tunnel diameter (PW/D) and the safety factor of the pillar is underestimated because the variation of deviation stress is relatively small even when the pre-stressing is applied to the tension bolt. In addition, the average safety factor proposed by Hoek and Brown(1980) was reviewed, but the pillar safety factor was relatively overestimated when the width of the pillar was increased. As an alternative, the SRM safety factor using shear strength reduction method shows the effect of changing the safety factor in the case of no reinforcement and tension bolt reinforcement as the pillar width/tunnel diameter(PW/D) changes. The failure shape is also similar to the previous limit theory result. In this study, the safety factor was evaluated without considering rock bolt and shotcrete to distinguish reinforcing effect of tension bolt.

• Journal of The Korean Association For Science Education
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• v.27 no.1
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• pp.28-36
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• 2007

This study investigated the influences of small group discussion and students' visual learning style in learning chemical concepts with drawing and writing as methods to assist students in connecting and integrating multiple external representations. Seventh graders (N=449) at a coed middle school were assigned to individual drawing (ID), pair drawing (PD), individual writing (IW), and pair writing (PW) groups. All students learned "Boyle's Law" and "Charles's Law" for two class periods. Analyses of the results revealed that the students in the PD group, regardless of students' visual learning style, scored significantly higher than those in the ID group in a conception test. The scores of the students with strong visual learning preference in the PW group were significantly higher than those in the IW group in the conception test, while the scores of the students with weak visual learning preference were not significantly different between the two groups. Although the conception test scores of the PD group were higher than those of the PW group, the difference was relatively small. It was found that most students in both PD and PW groups perceived pair drawing and pair writing positively upon cognitive and motivational aspects.

• Proceedings of the Korea Database Society Conference
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• 2001.06a
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• pp.106-112
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• 2001

o CRM이란 기업이 모든 기업 활동을 고객 지향적으로 관리하기 위한 전략적, 프로세스, 조직적, 기술적 변화 과정 자체를 의미함. 기업은 고객과 관련한 지식을 획득하여 각 조직으로 확산시키고, 다양한 방법으로 고객과 만나면서 그러한 정보를 활용하게 되며, 그 결과 기업의 매출이 증대되고 기업이 효율적으로 활동하게 됨(Gartner Group) (중략)

• Information Systems Review
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• v.1 no.2
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• pp.123-136
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• 1999

• Proceedings of the Korean Society of Potoscience Conference
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• 2002.06a
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• pp.92-92
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• 2002

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.3
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• pp.1-8
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• 2009

This thesis has analyzed the effect of the surge happening in flight on the engine performance, especially on the PW4000 turbofan engine. It is to be judged that the flight surge can occur more often at the time of takeoff than it does en route due to the fact that the engine parameters are prone to fluctuate. EPR is judged to be the most highly sensitive parameter responding when surge occurs. Both Engine rpm and Wf decrease almost simultaneously just like an EPR. During the take-off rolling, N1 vibration is more sensitive than the N2 vibration. Consequently, the surge can be detected by EGT increase, while the other parameters (EPR, rpm, Wf, etc) decrease.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.451-455
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• 2012

In this paper, Nateon, MSN Messenger, including how to hack into the most intimate acquaintance formed as follows, for hacking (keyloggers, remote monitoring, etc.) by sending a bank and ID, PW, certificate, security card, etc. personal financial information obtained after the withdrawal of the account balance to have a personal financial analysis infringement attack vulnerable elements found in internet banking, the vulnerabilities and countermeasures concerning the prevention of accidents, including violations by seeking a more secure Internet banking personal Internet Banking is to devise a deal.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.9-18
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• 2005

In order to systematically and visually understand well-known but qualitative and rotatively complicated relationships between synoptic fields in the BAIU season and heavy rainfall events in Japan, these synoptic fields were classified using the Self-Organizing Map (SOM) algorithm. This algorithm can convert complex nonlinear features into simple two-dimensional relationships, and was followed by the application of the clustering techniques of the U-matrix and the K-means. It was assumed that the meteorological field patterns be simply expressed by the spatial distribution of wind components at the 850 hPa level and Precipitable Water (PW) in the southwestern area including Kyushu in Japan. Consequently, the synoptic fields could be divided into eight kinds of patterns (clusters). One of the clusters has the notable spatial feature represented by high PW accompanied by strong wind components known as Low-Level Jet (LLJ). The features of this cluster indicate a typical meteorological field pattern that frequently causes disastrous heavy rainfall in Kyushu in the rainy season. From these results, the SOM technique may be an effective tool for the classification of complicated non-linear synoptic fields.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.82-85
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• 2018

The purpose of this paper is to improve the authentication method for IP camera user authentication. Since existing authentication uses knowledge-based authentication method, if ID and PW are exposed to attack by attacker, IP camera becomes defenseless from attacker. The attacker can access the IP Camera and acquire and distribute real time video and voice, which can be exploited as a second crime, and there is a fear of a secret leak when a secret facility is installed. In order to compensate for this vulnerability, this paper proposes a DUI authentication method that identifies and registers a device using DUI (Device Unique Identifier), blocks access to unauthorized devices by subordinating the device to the IP Camera and authenticates only authorized devices.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1333-1337
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• 1987

본 연구는 머리운동 제어 시스템에 대한 생체 물리학적인 모델링과 시뮬레이션을 통하여 모델의 동특성을 조사하였으며, 생체운동(머리-안구)의 상호 관계를 비교하였다. 결과를 요약하면 다음과 같다. 1) 시스템을 구성하고 있는 매개변수의 변화가 출력에 미치는 영향을 조사하기 위해 감도해석법을 써서 감도계수를 구한 결과, 입력 제어신호의 펄스높이(PH), 동근의 펄스폭(PW1), 길항근의 펄스폭(PW2)이, 시스템의 출력특성을 결정하는 가장 중요한 매개변수 임을 알 수 있었다. 2) 비 선형 제어모델의 선형화를 통하여 선형모델의 응답특성과 크나큰 차이가 없음을 알았다. 3) Main-Sequence도를 작성하여 실험 데이터와 비교한 결과, 거의 일치함으로서 모델의 타당성을 입증하였다. 4) 머리운동이 시간최적으로 응답하기 위해서는 bang-bang 제어법칙이 적용되어야 함을 알았다. 5) 머리운동이 목표점에 도달하는 순간에는 길항근의 역제통 펄스가 가해 짐으로서, 길항근이 궤적의 마지막 부분을 지배함을 알았다. 6) 머리-안구운동의 main-sequence도를 비교 함으로서 상호관계를 규명하였다. 앞으로는 이 모델링 법을 개선확장하면, 비행시 파일럿의 생체 시뮬레이션, 헬멧 조준 사격 시스템등의 항공공학, 생체의용공학 연구 및 제어입력을 생체신호로 하는 로봇틱스 연구에 본 연구 방법은 유용하리라 생각된다.