• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.2
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• pp.35-44
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• 2004

In the capacity spectrum method(CSM) using a linear response spectrum, the peak response of an inelastic system under a given earthquake load is estimated transforming the system into the equivalent elastic one. The CSM for estimating the peak inelastic response is evaluated in this paper. The equivalent period and damping ratio are calculated using the ATC-40, G lkan, Kowalsky, and Iwan methods, and the performance points are obtained according to the procedure B of ATC-40. Analysis results indicate that the ATC-40 method generally underestimates the peak response resulting in the unsafe design, while the G lkan and Kowalsky methods overestimate the responses. The Iwan method produces the values between those by the ATC-40 method and the G lkan and Kowalsky methods, and estimates the responses relatively closer to the exact ones. Further, it is found that the Kowalsky method gives the negative equivalent damping ratios depending on the hardening ratios, and thereby can not be used to estimate the responses in some cases.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.832-838
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• 2021

Recently, reports of marine accidents of small fishing vessels less than 10 tons have been increasing. In this study, the characteristics of the motion response in regular waves were analyzed using computations for these ships. Small vessels less than 10 tons are classified by size and used for marine accident investigations. Therefore, the motion response analysis was performed on three small fishing vessels of different sizes. In the case of the head sea, it was confirmed that as the speed of the vessel increased in the long wavelength region, the motion responses of heave and pitch became large. The motion response of the smallest 3-ton fishing vessel was greater than that of the other sizes of fishing vessels. The maximum value of the roll motion shifted to the long wavelength region as the speed gradually increased in the bow sea, regardless of the size of the ship. In all the three small fishing vessels, it was found that the roll motion was the greatest at 15 knots, the highest speed in both bow and beam seas. When sailing in the head sea and bow sea conditions, lowering the speed is one of the effective approaches to reduce the effects of the vertical and lateral plane motions. The roll motion caused by the beam wave showed a tendency to increase rapidly only at a specific wavelength regardless of the speed and the size of the vessel. It was confirmed that the roll motion was significantly reduced with forward speed in the stern wave compared to the bow wave. As there is a specific region where the maximum value of the hull motion response appears depending on the size and speed of the ship, an operation method that can minimize the effect of this motion should be considered and implemented.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.995-1006
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• 2022

The purpose of this study was to investigate the current status of practical course operation in a non-face-to-face online environment, learning effects, and students' experiences and perceptions for radiology major students using a survey. The questionnaire consisted of a total of 34 items in 5 areas: general characteristics of subjects, current learning participation in non-face-to-face environments, learning satisfaction, learning outcomes, improvement and requirements. For the analysis of the questionnaire responses, frequency analysis was performed on the response frequency, ratio, and scale for each item. Based on the general characteristics of the survey respondents, cross-analysis was performed using the chi-square test for participation in non-face-to-face learning, learning performance, and learning satisfaction. implemented. Improvements and requirements were qualitatively analyzed for the repetition frequency of words with the same meaning. Through the results of analyzing the responses of a total of 397 questionnaires, the direction of design and development of practical classes in a non-face-to-face environment in the future and basic information and implications for efficient operation were confirmed. Based on this, it is necessary to continue to think and make efforts for the efficient operation of non-face-to-face practice classes in the post-corona era.

• Journal of Digital Convergence
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• v.10 no.1
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• pp.323-333
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• 2012

Network traffic demand is increasing explosively because of various smart equipment and services on smart era. It causes of traffic overload for wireless and wired network. Network management system is very important to control the explosion of data traffic. It uses SNMP to communicate with various network resources for management functions and creates lots of management traffic. Those are can be serious traffic congestion on a network. I propose an improving function of SNMP to minimize unnecessary traffics between manager and agent for collecting the Trend Analysis Information which is mainly used to monitor and accumulate for a specific time period in this paper. The results of test show it has compatibility with the existing SNMP and greatly decreases the amount of network traffic and response time.

• Journal of Science Education
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• v.32 no.2
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• pp.103-120
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• 2008

The purpose of this study was to compare science teachers' perceptions with students' perceptions about the important aims of laboratory activities in science instructions, to identify whether there was a difference between them. For the purpose, the two questionnaires were designed; for secondary science teacher and secondary student. The samples selected in each group were 108 middle school teachers, 109 middle school students, 104 high school teachers, and 110 high school students. The survey responses from each group were analyzed through multiple response method. The results indicated that science teachers selected the science process skills as important aim of laboratory activity whereas students selected the ability for creative problem-solving and the central tendency of teachers' responses about certain item-science process skill was relatively higher than students' responses about certain item-the ability for creative problem-solving. From these results, we found there was the difference between teachers' perception and students perception about the important aims of laboratory activities in science instructions.

• Communications of Mathematical Education
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• v.35 no.1
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• pp.15-36
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• 2021

A well-designed mathematics lesson is the foundation for effective mathematics instruction. Given this significance, this paper focused on analyzing what would be important elements for in-service teachers in planning an elementary mathematics lesson. For this purpose, a total of 27 in-service teachers were asked to write down whatever they would consider important in designing a mathematics lesson. A mathematics lesson plan prepared by a pre-service teacher was provided for the in-service teachers. They were then asked to analyze the strengths of the lesson plan and to provide detailed feedback on how to improve it. The results of this study showed that the in-service teachers tended to analyze the given mathematics lesson plan in terms of what they considered important regarding lesson design. Such elements were specified when the in-service teachers described the strengths and feedback for improvement of the lesson plan. In particular, the aspects of instructional strategies and materials were explained in detail. Based on these results, this paper is expected to provoke discussions on lesson design of in-service teachers and subsequent research.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.2 s.48
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• pp.39-50
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• 2006

Site response analyses were peformed based on equivalent linear technique using the shear wave velocity profiles of 162 sites collected around the Korean Peninsula. The she characteristics, particularly the shear wave velocities and the depth to bedrock, are compared to those in the western United States. The site coefficients of short period $(F_a)$ and the long period $(F_v)$ obtained from this study were significantly different compared to 1997 Uniform Building Code (1997 UBC). $F_a$ underestimated the motion in shot period ranges and $F_v$ overestimated the motion in mid period ranges in Korean seismic guideline. It is found that the existing Korean seismic design code were is required to be modified considering geological site conditions in Korea for the reliable estimation of sue amplification. Problems of the current seismic design code were dicussed in this paper and the development of site classification method and modification of desing response spectra were discussed in the companion papers(II-Development of Site Classification System and III-Modification of Dosing Response Specra).

• Journal of The Korean Association For Science Education
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• v.33 no.6
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• pp.1248-1258
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• 2013

This study investigated the elementary school students' perception of the "purpose of scientists' experiments" and discovered what roles teachers can take to provide guidance. The study subjects were 193 elementary school students (96 boys and 97 girls) in a school located in Gyeonggi-do. The responses were analyzed through categorization based on their gender, science test score at school, and understanding of the purposes of scientific experiments based on students' choice of science-related future careers. The results of this study were as follows. In relation to the purpose of science experiments, the elementary school students considered intrinsic values of doing experiments more valuable than their extrinsic values. Next, 34.2% of the students answered that scientists do science experiment 'to find a new fact' and 26.9% of the students answered 'to make life convenient.' The results showed that girls responded 'social usefulness' more frequently than boys. Considering the achievement levels, it was found that high level students replied 'to make life convenient' more frequently than middle and low level students on why scientists do science experiments. Students who want to have a science-related career had varied ideas about it.

• Journal of the Society of Disaster Information
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• v.13 no.2
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• pp.258-266
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• 2017

Cable-stayed bridges are bridges with long spans for special purposes. Due to the long span, the dynamic response of the vehicle to the moving load is very special. The behavior also has nonlinear, which makes it difficult to design. In this study, the responses of cable - stayed bridges are considered considering various vehicle loads and the behavior of long - span bridges under moving loads is investigated. Especially, when the loads for one direction and for both directions move with speed, the behavior of the bridges is found to be due to the flexibility of the cable. It can be seen that the analysis including the dynamic behavior of the cable and the top plate is more effective because the influence of the vehicle load tends to amplify the vertical deformation together with the vibration of the cable.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.87-93
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• 1993

The motion response of a ship moored in a rectangular harbor excited by long waves has been studied theoretically and experimentally. Experiments are performed in a shallow basin. A ship model is set moored by soft springs at various positions in a model harbor subjected to regular waves with period ranging from 2 to 3 seconds. Wave and ship responses are measured and compared with theory. It is found that theoretical results agree qualitatively with experimental results. The main source of quantitative discrepancies is presumably due to real fluid effects such as separation at the harbor entrance and friction on harbor boundaries.