• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.51-59
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• 2004

An experimental procedure to identify failure modes of impact damage using sensor signals and to analyze their general features is examined. A series of low-velocity impact tests from low energy to damage-induced high energy were performed on the instrumented drop weight impact tester to monitor the stress wave signals due to failure modes such as matrix cracking, delamination, and fiber breakage. The wavelet transform(WT) and Short Time Fourier Transform(STFT) are used to decompose the piezoelectric sensor signals in this study. The extent of the damage in each case was examined by means of a conventional ultrasonic C-scan. The PVDF sensor signals are shown to carry important information regarding the nature of the impact process that can be extracted from the careful signal processing and analysis.

• Journal of Korea Port Economic Association
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• v.31 no.3
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• pp.41-60
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• 2015

This paper investigates whether managerial ownership and foreign ownership have impacts on firm value, using a sample of logistics firms listed on the Korea Stock Exchange between 2008 and 2014. In the Korean economy, family-controlled business groups, known as chaebol, constitute a unique governance system. To acquire investments from controlling shareholders, a logistics firm is likely to be included in family-controlled business groups. Since reform of the governance structure of logistics firms in the South Korea enables shareholder value to be maximized, we analyzed ownership effects on firm value using pooled ordinary least squares. Empirical results showed that there was a significant positive relation between managerial ownership and firm value. This study also found that there was a significant positive relation between foreign ownership and firm value. We thus show that both managerial ownership and foreign ownership can protect shareholders by positively affecting firm values.

• Journal of Korean Society of Archives and Records Management
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• v.18 no.1
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• pp.155-175
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• 2018

The purpose of this study is to establish a classification system for the records of the Association for the Bereaved Families of the Hampyeong Massacre Victims. The content of the records is accordingly implemented through a functional source principle, and a classification table is presented in such a way that it reflects the characteristics by type and by production period so that the records can be used effectively. DIRKS, a methodology for the development of the functional classification system, is used to conduct a functional analysis of Hampyeong massacre victims' families to derive a task classification table that leads to task function-work activity-handling actions. The category is determined by taking into consideration the type and nature of the time of the production of the records of the Hampyeong massacre victims' families. The records are mapped according to the function classification system, which corresponds to the task classification table, and the multicategory system that drafts the type and period, which is used to classify the functions. The medical institution introduces a system for classifying records into task subjects, task activities, handling actions, types, and period.

• Journal of the Korean Chemical Society
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• v.62 no.5
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• pp.386-397
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• 2018

In this study, we investigated the characteristics of the PCK components in the chemistry units of middle school science teacher's guidebooks developed under the 2009 Revised National Curriculum. The analysis of the results revealed that the sub-components of topic-specific strategies, vertical articulation, and lesson objectives were systematically handled in most teacher's guidebooks. However, subject-specific strategies, assessment methods, and curricular changes were mainly dealt with only in the general guidelines. Experiments and inquiries, assessment questions, and assessment dimensions were lack of constructivist approaches in the aspect of presented contents or forms. Horizontal articulation and knowledge of students were either lacked in relevant content or presented in the form of simple presentation. Concepts and theories accounted for the largest proportion of teachers' guidebooks, but some of them were beyond appropriate levels. On the bases of the results, the implications for the development of the teacher's guidebooks are discussed.

• Korean System Dynamics Review
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• v.12 no.3
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• pp.47-66
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• 2011

South Korea has achieved remarkable social and economic development together with the process of democratization over the past 20 years. In the democratic process in South Korea, ordinary people have actively participated in conventional political activities such as elections. But recently, one of the salient phenomena is that the public have been showing political apathy associated with a light poll. Especially, the most serious concern in the political environment of South Korea is that young voters (e.g., 20-30s) have serious political apathy leading to low voter turnout. Regarding this concern, many political scientists argued that this political phenomenon is not only the case in South Korea, insisting that many consolidated democratic countries such as European countries and the US have the same problems. However, South Korea has contained different factors (e.g., historical, culture, social, and political differences) leading to political apathy and light poll. Unfortunately, no one has clearly explain the phenomenon. In fact, in order for scholars to understand and explain these concerns, they should carefully look at the phenomenon with diverse perspectives and approaches. The main purpose of this paper is to explain why the digital generation has political apathy and are reluctant to participate in political activities such as voting. Using causal loop analysis which is based on systematic thinking, we not only analyzed the pattern of the digital generation' political participation with regard to diverse perspectives, but also attempted to draw new political implications from the analysis. Based on our analysis, we tried to suggest some implications for political stability and development in South Korea in the future.

• Fire Science and Engineering
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• v.32 no.1
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• pp.76-80
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• 2018

The present study investigates the hydrodynamic force acting on the vertical wall of a portable water storage tank which has reentrant bottom topology. To numerically simulate the lapping waves in the tank, functional iterative method for the linearized Peregrine's model which numerically simulates the propagating waves over the slowly-sloped bottom topology is introduced. The numerical experiment condition is controlled to adjust the position and the height of the water supplying nozzle. Finally, it is observed that the maximum wave height at the vertical wall and the ratio of hydrodynamic force to hydrostatic one are amplified accordingly. Therefore it must be give attention to this bad effect of amplified hydrodynamic force by the supply method of fire water in order to have the structural stability of the portable water storage tank when it was used on the reentrant bottom topography.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.41-46
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• 1993

A strain showing antibiotic activities against various bacteria and fungi was selected from approximately 2,000 microorganisms obtained from soil samples. This strain, designated as KH-431, was identified as a Clostridium sp. by its morphological, physiological and biochemical characteristics. The highest production of the antibiotics was achieved in a fermentation medium containing sorbitol, yeast extract, d-biotin and $CaCl_2$ The antibiotics were isolated from the culture broth by solvent extraction using ethyl acetate, silica gel column chromatography and recrystallization. Two kinds of antibiotics, KG-431A and KG-431B were obtained after the purification procedure, and only KG-431B was successful to recrystallize.

• Journal of the Institute of Convergence Signal Processing
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• v.9 no.3
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• pp.188-194
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• 2008

We propose the new method for the traffic signs recognition that is one of the DAS(Driving assistance system) in the intelligent vehicle. Our approach estimates a varied degree by using a geometric method from the varied traffic signs in noise, rotation and size, and extracts the recognition symbol from the compensated traffic sign for a recognition by using the sequential color-based clustering. This proposed clustering method classify the traffic sign into the attention, regulation, indication, and auxiliary class. Also, The circular tracing method is used for the final traffic sign recognition. To evaluate the effectiveness of the proposed method, varied traffic signs were built. As a result, The proposed method show that the 95 % recognition rate for a single variation, and 93 % recognition rate for a mixed variation.

• Korean Educational Research Journal
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• v.38 no.1
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• pp.1-16
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• 2017

The third national curriculum had the characteristics to establish guidelines in history textbooks with the basic direction to implement the charter of national Education. At that time, the object of the history education was 'the harmony with the development of the individuals and national development' which was the same that the authorized government aimed at. But the characters and the purpose were repeated without any criticism. Since the third national curriculum was presented in Korean education, the aims of education proposed the 'Korean style democracy'. Essential aims of education are more important than any political issues because academic research is not reflected on nationalism. This trend which is flowing in the education of Korea was strengthened through the education authorities in the statements of 'Deployment of the Governing' or 'guidelines': Especially, the idea and the history education. Despite the curriculum has been amended several times, these problems are not to be gotten rid of. The recently revised curriculum guidelines for history textbook description should improve and find the way to develope the history thinking of students.

• Korean Journal of Ichthyology
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• v.20 no.1
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• pp.1-6
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• 2008

Three types of clonal cell lines were isolated according to their size and phenotype from the adherent cell populations in long-term liquid cultures from the embryonic fibroblast cells of Zebrafish, Danio rerio. All kind of cell lines were well proliferated. The size and number of clonal cell lines derived colonies from stable embryonic cells were significantly increased in the presence of NAC and A2P conditioned medium from the cell lines. The stable cell lines and clonal cell lines were cap-able of well proliferation in vitro. These cell lines have been maintained in continuous culture without change in characteristics. A majority of the clonal cells (80%) was shown a normal chromosomal complement (50 chromosomes, 2N) in according with FACs analysis. Majority of cells were positive to vimentin staining and none of them were positive for nestin and Oct -4 by immunocytochemistry. These results indicate that the clonal cell lines obtained from cultured cells are fibroblasts and may be extremely useful in genetic manipulation for further nuclear transfer and fish cloning.