• Earthquakes and Structures
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• v.4 no.4
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• pp.397-428
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• 2013

This paper examines whether the "effective period" of bilinear isolation systems, as defined invariably in most current design codes, expresses in reality the period of vibration that appears in the horizontal axis of the design response spectrum. Starting with the free vibration response, the study proceeds with a comprehensive parametric analysis of the forced vibration response of a wide collection of bilinear isolation systems subjected to pulse and seismic excitations. The study employs Fourier and Wavelet analysis together with a powerful time domain identification method for linear systems known as the Prediction Error Method. When the response history of the bilinear system exhibits a coherent oscillatory trace with a narrow frequency band as in the case of free vibration or forced vibration response from most pulselike excitations, the paper shows that the "effective period" = $T_{eff}$ of the bilinear isolation system is a dependable estimate of its vibration period; nevertheless, the period associated with the second slope of the bilinear system = $T_2$ is an even better approximation regardless the value of the dimensionless strength,$Q/(K_2u_y)=1/{\alpha}-1$, of the system. As the frequency content of the excitation widens and the intensity of the acceleration response history fluctuates more randomly, the paper reveals that the computed vibration period of the systems exhibits appreciably scattering from the computed mean value. This suggests that for several earthquake excitations the mild nonlinearities of the bilinear isolation system dominate the response and the expectation of the design codes to identify a "linear" vibration period has a marginal engineering merit.

• Journal of Astronomy and Space Sciences
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• v.23 no.1
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• pp.55-70
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• 2006

There are many astronomical records of comets in Korean history books. We collected those of the comet that appeared in the winter of the year 1664. These records were written in Daily Reports of the Royal Observatory on Astronomical Events (星變測候單子), Final Reports of the Royal Observatory on An Astronomical Events (天變謄錄), the Daily Records of the Royal Secretariat of the Joseon Dynasty (承政院日記), and the Chronicle of the Joseon Dynasty (朝鮮王朝實錄). We used the Olbers' method for determination of preliminary orbit of the comet, and compared the result with the previous researches. In the Oblers' method the orbit is assumed to be parabolic (e=1). We obtained the following orbital elements: perifocal distance q=1.07\pm0.008AU, perifocal passage time $T=2329165.50\pm0.72$ days, argument of the perifocus $\omega=318^{\circ}.2\pm2^{\circ}.29$, longitude of ascending node $\Omega=85^{\circ}.23\pm2^{\circ}53(J1665)$(J1665), inclination $i=160^{\circ}.28\pm1^{|circ}.56$.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.394-399
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• 2004

Increased cumulative running times of railroad vehicle brings out such degradation as wear and fatigue. It don't adapt corrective maintenance which repairs a poor pan after a trouble but use preventive maintenance which fixes a bad part before a trouble. There were a few researches for preventive maintenance such as inspect affairs and facilities management. They couldn't estimate the operation reliability on railroad vehicle. Therefore, this study proposes the preventive maintenance procedure that predict repair period of end beam for uncovered freight car using reliability function and instantaneous failure rate on the basis of fatigue test and load history data.

• Journal of Science of Art and Design
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• v.11
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• pp.79-108
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• 2007

"Printing is an Art of reproduction & a Technique of However printing has extended its limitation from a genre of reproduction itself and now it stands on the turning point as an art such as painting or sculpture which expresses artist's originality. Early Printing has had relations in depth with press printing in terms of information recording, preservation, and transmission. It was acknowledged value in a way of information satisfaction different from how it is valued as a pure art today. But, later printing has transferred its function from a mean of reproduction to pure art due to the development of printing skills and photography invention. It can be said that the concept of modern printing is taking over its genealogy as a creative work not as just printing. Also its expression capability is widen to dimensional printing and high-tech multimedia from original tradition techniques. As we discussed above, modern painting is very open to various changes. This modern painting aspect can be seen as an extended interpretation of 'board' concept. This dissertation raises a question why monotype and monoprint couldn't secure its position in printing history in spite of numerous artists' tryouts in its way. Monotype and monoprint fundamentally based on intaglio technique in its history. Yet, its systematic study hasn't been worked out. This is because of the lack of recognition of monotype and monoprint's originality as printing. Especially in monoprint, it has known as an early stage in copperplate printing process which is an attempt to solve the technique limitation or trial work for edition. Likewise the reason why monotype and monoprint remains at the edge of printing border ambiguously is because of conceptual, technical characteristics which are against traditional printing. In traditional printing, the concept of board is important as a method of reproduction. Different from the fact, monotype and monoprint accept the form of medium 'board' conceptually out of limited condition as mentioned. Thus monotype and monoprint hasn't stand out for several reasons until late 20th century when it started come out to public as people starts to have interests that works from famous artists are actually based on monotype and monoprint. This dissertation likes to step into the monotype and monoprint theoretically which is not well known in domestic and try to study the meaning of monotype and monoprint as a printing medium which is also hasn't been considered sincerely. For this study the process follow as below. First, look into how monotype and monoprint has a concept and history. Next, check differences through comparison with traditional printing and how printing can be understood in what aspects at the same time. After, verify how monotype and monoprint have influence on the acceptance of extended concept of 'board'. This study will show the expressional possibility of monotype and monoprint which has already known as 'tableau printing' in today's situation where adventurous experiments of printing medium are going on with the development of technology.

• Computers and Concrete
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• v.4 no.6
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• pp.437-456
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• 2007

The shrinkage of large reinforced concrete floors often gives rise to cracking problems. To identify the problematic areas, shrinkage movement analysis is often carried out by finite element method with proper creep and shrinkage models using step-by-step time integration. However as the full stress history prior to the time interval considered is necessary, with the increase in the number of time intervals used, the amount of computations increases dramatically. Therefore a new method using the shrinkage-adjusted elasticity modulus (SAEM) is introduced so that analysis can be carried out using one single step. Examples are presented to demonstrate its usefulness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.652-658
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• 2019

When IoT is applied to various research experiment fields such as physics, pharmacy, biology and medicine, it can increase the safety and convenience of researchers by intelligently monitoring and controlling research equipment and environment with various sensors and devices. For accurate and convenient record management and the research history and the basis but also for the reverse tracking, real-time reagent measurement and registration should be provided as a research support automation services. Currently, existing methods of reagent management are operated by computerized method, but reagent registration and management are not automated. And also record is managed manually, there are many hassles and problems such as a record error and too much time required for quantification and registration for many reagents. In this paper, we study a real time reagent measuring and registration method based on IoT to resolve the problems aforementioned, by the information of the reagent acquired by image recognition and NFC method.

• Journal of the Korea Society of Computer and Information
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• v.13 no.2
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• pp.41-50
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• 2008

This paper proposes the recommendation system which is a new method using RFM method in mobile internet environment. Using a implict method which is not used user's profile for rating, is not used complicated query processing of the request and the response for rating, it is necessary for user to keep the RFM score about users and items based on the whole purchased data in order to recommend the items. As there are some problems which didn't exactly recommend the items with high purchasablity for new customer and new item that do not have the purchase history data. in existing recommendation systems, this proposing system is possible to solve existing problems, and also this system can avoid the duplicated recommendation by the cross comparison with the purchase history data. It can be improved and evaluated according to the criteria of logicality through the experiment with dataset, collected in a cosmetic cyber shopping mall. Finally, it is able to realize the personalized recommendation system with high purchasablity for one to one web marketing through the mobile internet.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.473-485
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• 2017

An isolated building, composed of superstructure and isolation system which have very different damping properties, is typically non-classical damping system. This results in inapplicability of traditional response spectrum method for isolated buildings. A multidimensional response spectrum method based on complex mode superposition is herein introduced, which properly takes into account the non-classical damping feature in the structure and a new method is developed to estimate velocity spectra from the commonly used displacement or pseudo-acceleration spectra based on random vibration theory. The error of forced decoupling method, an approximated approach, is discussed in the viewpoint of energy transfer. From the base-isolated benchmark model, as a numerical example, application of the procedure is illustrated companying with comparison study of time-history method, forced decoupling method and the proposed method. The results show that the proposed method is valid, while forced decoupling approach can't reflect the characteristics of isolated buildings and may lead to insecurity of structures.

• Journal of the Korean Society for Library and Information Science
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• v.18
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• pp.277-325
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• 1990

The purpose of this study was to determine the effectiveness of instructors' utilization of the reserve collection in the university library. To accomplish this, an experiment-and-questionnaire study was done by selecting an experimental group for whom the teaching method utilizing the reserve collection was used and a control group for whom the method was not used. An experimental group and a control group studied were as follows: (1) Students take the 'Comparative Politics' course in the Department of Political Science. (2) Students take the 'History of 'English Literature' course III the Department of English Language and Literature. The data to test the hypothesis were analyzed by SPSS/PC+ routine. The results are as follows: (1) There were significant differences between the experimental group and the control group in academic achievement(T(228)=6.69, P<.01). To investigate the difference in effect by major, the one-way analysis of variance was employed. According to the results, there were significant differences between the experimental group and the control group In the Department of Political Science and the Department of English Language & Literature. Therefore, students for whom the teaching method utilizing the reserve collection was used have higher academic achievement than those for whom the method was not used. (2) As for the degree of utilizing the library and its materials, there were significant differences between the experimental group and the control group(T(228)=8.87, P<.01). As for the results of the one-way analysis of variance to investigate the difference in effect by major, there were significant differences between the experimental group and the control group in both departments. As for the degree of utilizing library catalogues and bibliographical tools, there were significant differences between the experimental group and the control group(T (228)=8.55, P<.01). As stated earlier, the one-way analysis of variance to investigate the difference in effect by major has shown that there were significant differences between the experimental group and the control group in both departments. As for the degree of sincerity in doing homework and writing papers, there were significant differences between the experimental group and the control group(T(176)=8. 03, P<.01). To investigate the difference in effect by major, the one-way analysis of variance was again employed. According to the results, there were again significant differences between the experimental group and the control group in both departments. So, the students for whom the teaching method utilizing the reserve collection was employed used library catalogues and bibliographical tools much more than those for whom the method was not employed, and were more sincere in doing homework and writing papers. (3) There were also significant differences between the experimental group and the control group in degree of satisfaction in taking the course (T (228) = 6.61, P<.01). The results of the one-way analysis of variance to investigate the difference in effect by major was that there were significant differences between the experimental group and the control group in both departments. Therefore, the degree of satisfaction of students who were taught by the teaching method utilizing the reserve collection is higher than that of those who were not taught by the method. On the other hand, the responses of the experimental groups of two departments as to the degree of satisfaction with their teaching method was investigated. The result shows that students who took the 'Comparative Politics' course in a small class which employed the seminar method were higher in degree of satisfaction with the teaching method than students who took the 'History of English Literature' course III a large class which employed a lecture-oriented teaching method.

• Journal of Korean Public Health Nursing
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• v.28 no.2
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• pp.320-332
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• 2014

Purpose: This study was conducted in order to examine premenstrual symptoms (PMS) according to physical activity of high school girls. Method: Data were collected from 323 high school girls using structured questionnaires, Menstrual Distress Questionnaire (MDQ) and International Physical Activity Questionnaire (IPAQ). The data were analyzed using descriptive statistics, t-test, and AVOVA. Results: The mean score of PMS was low (2.200.81). Among the subcategories, negative feeling (2.491.26) was the highest. Physical activity levels were coded as inactive, minimal activity and health enhancing physical activity, among which minimal activity (53.0%) was the highest. Significant differences in PMS were observed according to subjective health condition (F=10.83, p<.001), alcohol intake (t=-1.99, p=.048), caffeine intake (F=3.04, p=.029), dietary habit (F=4.78, p=.009), amount of menstruation (F=4.57, p=.011), discomfort in daily life (F=28.94, p<.001), degree of menstrual pain (F=41.23, p<.001), method of menstrual pain relief (F=4.29, p=.015), and family history (F=11.45, p<.001). Significant difference in PMS was observed according to the physical activity level (F=3.12, p=.046), and health enhancing physical activity (2.540.87) was the highest. Conclusion: These findings suggest that PMS intervention programs would be considered factors related to PMS. Conduct of further studies is recommended for evaluation of the relationship between physical activity and PMS.