• International Journal of Contents
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• v.13 no.2
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• pp.6-13
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• 2017

It is a well-known fact that Internet addiction adversely affects mental health of adolescents. This study was conducted to determine whether there is a difference in the experience of depression according to the level of Internet addiction. Participants included 73,238 middle and high school students from the Korean Youth Risk Behavior Web-based Survey (KYRBWS) conducted in 2010. The level of Internet addiction and the experience of depression were assessed using self-diagnosis questionnaires. Multiple logistic regression analysis was used to identify the association between Internet addiction and depression. High-risk and potential-risk Internet users were 1.61 times and 1.21 times more likely to experience depression, respectively, than normal Internet users. The increase in depression was more significant in girls students. Acknowledging the connection between Internet addiction and depression, the problem should be tackled from the perspective of school health by providing systematic Internet addiction prevention and treatment programs.

• The Journal of the Korea Contents Association
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• v.4 no.1
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• pp.49-55
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• 2004

DDoS is an attack type that interfere with normal service by running out network bandwidth, process throughput, and system resource. It can be recognized intuitively by network slowdown and connection impossibility state, but it is necessary to detect DDoS attack by exact and quantitative analysis. In this paper, the exact and efficient DDoS attack detection system which is able to detect traffic flooding by MIB information, and attack traffic by packet analysis is proposed and realized.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.875-878
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• 1998

In this thesis, we present efficient techniques to reduce the switching activity in a CMOS combinational logic network based on local logic transforms. But this techniques is not appropriate in the view of testability because of deteriorating the random pattern testability of a circuit. This thesis proposes a circuit design method having two operation modes. For the sake of power dissipation(normal operation mode), a gate output switches as rarely as possible, implying highly skewed signal probabilities for 1 or 0. On the other hand, at test mode, signals have probabilities of being 1 or 0 approaching 0.5, so it is possible to exact both stuck-at faults on the wire. Therefore, the goals of synthesis for low power and random pattern testability are achieved. The hardware overhead sof proposed design method are only one primary input for mode selection and AND/OR gate for each redundant connection.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.939-942
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• 1997

In chemical mechanical polishing(CMP) there are many factors affecting the results. Temperature is one of the factors and it affects the removal rate. That is, the higher it arise, the more the material is removed. But the detailed temperature behavior is not discovered. In this study, we discover the distribution of temperature across the pad where the wafer has just been polished. And then we reveal the cause of the result in connection with the mechanical structure. In addition, we also discover the relationship of the friction force and normal force. With the result of two forces, we get the friction coefficient and obtain the contact model of the wafer and pad.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.71-72
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• 2010

This paper deals with the SCR thyristor switching characteristics of a 3-phase voltage disturbance generator. The series transformers of the generator require bypass SCR thyristors to provide the source voltage to the output terminal in normal operating mode. The SCR thyristor switching characteristics is quite different according to the connection point to the series transformer. The switching characteristics is analysed and verified through simulation results.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.532-533
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• 2010

This paper deals with the SCR thyristor switching characteristics of a 3-phase voltage disturbance generator. The series transformers of the generator require bypass SCR thyristors to provide the source voltage to the output terminal in normal operating mode. The SCR thyristor switching characteristics is quite different according to the connection point to the series transformer. The switching characteristics is analysed and verified through simulation results.

• Journal of Chest Surgery
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• v.22 no.2
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• pp.202-211
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• 1989

We experienced a series of animal experimental studies of the total artificial heart in 1988. So called, "Korean Heart* was used in this study, which is developed and fabricated in the Department of Biomedical Engineering, College of Med., S.N.U.. "Korean Heart" is a Rolling-Cylinder Motor-Driven type which is a newly developed electromechanical heart over the shortcomes of the previous artificial hearts, especially pneumatic type. The advantages of the "Korean Heart" are total implantability, quiet and smooth movement, small size fittable in oriental people, etc. The animal experiments were performed two times, as an assist device in sheep and total artificial heart implant experiment in calf weighing 100 kg. After total implantation, the artificial heart was well functioned in movement and hemodynamic control. So that, the calf was recovered excellently, which was able to stand up by herself and take an oral intake. Total survival time was 100 hours and the cause of death was a sudden pumping failure [electrical connection problem]. Several postoperative laboratory results almost within normal limits and no hemolysis, but in autopsy, the multiple thromboembolic findings were seen at the lung and kidney.n at the lung and kidney.

• Journal of the Chungcheong Mathematical Society
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• v.31 no.1
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• pp.137-149
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• 2018

In this paper, under the assumption of the symmetry point spread function, antireflective boundary conditions(AR-BCs) are considered in connection with the fast truncated Lagrange(FTL) method. The FTL method is proposed as an image restoration method for large-scale ill-conditioned BTTB(block Toeplitz with Toeplitz block) and BTHHTB(block Toeplitz-plus-Hankel matrix with Toeplitz-plus-Hankel blocks) linear systems([13, 17]). The implementation and efficiency of the FTL method in the AR-BCs are further illustrated. Especially, by employing the AR-BCs, both the continuity of the image and the continuity of its normal derivative are preserved at the boundary. A reconstructed image with less artifacts at the boundary is obtained as a result.

• Research in Mathematical Education
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• v.16 no.3
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• pp.177-194
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• 2012

What strategies are used to help students understand quadratic functions in mathematics classroom? In specific, how does Chinese teacher highlight a connection between algebraic representation and graphic representation? From October to November 2009, an experienced teacher classroom was observed. It was found that when students started learning a new type of quadratic function in lessons, the teacher used two different teaching strategies for their learning: (1) Eliciting students to plot the graphs of quadratic functions with pointwise approaches, and then construct the function image in their minds with global approaches; and (2) Presenting a specific mathematical problem, or introducing conception to elicit students to conjecture, and then encouraging them to verify it with appoint approaches.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.231-234
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• 2005

Steel braced frames retrofit method has been broadly used due to their effectiveness in both light weight and construction periods. However, steel braced frames retrofit method has difficulties in application on the inner frames of buildings to be retrofitted consequently, there have been demands for the braced frames retrofit method that can be broadly and easily applicable to both inner and outer frames of the buildings. The objective of this study is to develop and evaluate the seismic retrofit method applicable to the inner frame also by dividing the reinforcing frames into three unit. From the cyclic test of specimens, the test results dearly showed that steel brace using HPFRCCs and steel bars ensure the better cyclic compressive performance than the normal braced members.