• Economic and Environmental Geology
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• v.27 no.6
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• pp.557-561
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• 1994

Q estimates are made by direct measurements of energy loss per cycle from primary P and S waves, as a function of frequency. Assuming that intrinsic Q is frequency independent and scattering Q is frequency dependent over the frequencies of interest, the relative contributions of each, to a total observed Q, may be estimated. Test examples are produced by computing viscoelastic synthetic seismograms using a pseudo spectral solution with inclusion of relaxation mechanisms (for intrinsic Q) and a fractal distribution of scatterers (for scattering Q). The composite theory implies that when the total Q for S-waves is smaller than that for P-waves (the usual situation), intrinsic Q is dominating; when it is larger, scattering Q is dominating. In the inverse problem, performed by a global least squares search, intrinsic $Q_p$ and $Q_s$ estimates are reliable and unique when their absolute values are sufficiently low that their effects are measurable in the data. Large $Q_p$ and $Q_s$ have no measurable effect and hence are not resolvable. Standard deviation of velocity $({\sigma})$ and scatterer size (A) are less unique as they exhibit a tradeoff as predicted by Blair's equation. For the P-waves, intrinsic and scattering contributions are of approximately the same importance, for S-waves, the intrinsic contributions dominate.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.60-65
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• 2008

Current soil remediation principles for toxic metals have some limitations even though they vary with different technologies. An alternative technology that transforms hazardous substances into nonhazardous ones would be environmentally beneficial. Objective of this research was to assess optimum conditions for Cr(VI) reduction in soils as influenced by ZVI(Zero-Valent Iron), organic matter and moisture content. The reduction ratio of Cr(VI) was increased from 37 to 40% as organic matter content increased from 1.07 to 1.75%. In addition, Cr(VI) concentration was reduced as soil moisture content increased, but the direct effect of soil moisture content on Cr(VI) reduction was less than 5% of the Cr(VI) reduction ratio. However, combined treatment of ZVI(5%), organic matter(1.75%) and soil moisture(30%) effectively reduced the initial Cr(VI) to over 95% within 5 days and nearly 100% after 30 days by increasing oxidation of ZVI and concurrent reduction of Cr(VI) to Cr(III). The overall results demonstrated that ZVI was effective in remediating Cr(VI) contaminated soils, and the efficiency was synergistic with the combined treatments of soil moisture and organic matter.

• Journal of Korean Orthopaedic Sports Medicine
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• v.1 no.1
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• pp.49-54
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• 2002

Purpose : To analyze the clinical results of treatment for the osteochondritis dissecans of femoral condyle by age, the type of lesion and method of treatment. Methods : From March 1991 to February 2000, 17 patients (20 cases) with osteochondritis dissecans of the femoral condyle were followed up over 1 year. Three patients had bilateral lesion. There were 12 cases with trauma history (9 cases with sports injury and 3 cases with direct trauma). The initial symptoms were pain, clicking, locking, giving way in the order of frequency, pain was revealed in all cases. Clinical evaluation of IKDC and Hughston method were used for subjective and objective function. Results : The number of male patient was 12, and the mean age was 19.8 year old (11$\~$50). The location of the lesion was 14 cases in medial femoral condyle and 6 cases in lateral femoral condyle. The arthroscopic findings of the lesion in 15 cases were as follows, early separation in 6 cases, partially detachment in 4 cases, and crators and complete detachment in 5 cases. 5 cases were treated with mutiple drilling and 5 cases with Herbert screw fixation, 3 cases with Herbert screw fixation and bone graft. In early stage, 7 cases were treated with conservative method. In the grading of Hughston score, 6 cases were graded as excellent, 9 cases as good, 15 cases were graded as good to excellent. Based on the IKDC scale, 1 case was graded as normal, 6 as nearly normal, and 10 as abnormal. Conclusions : The trauma seemed to be important factor in occurrence of osteochondritis dissecans of the femoral condyle. The clinical results of juvenile period showed better than adolescence and adult period, it is necessary to detect the lesion as soon as possible. The result of subjective evaluation was worse than the Hughston evaluation. It was caused by limiting involvement of sports activity and limited activity in the adolescence.

• Journal of Intelligence and Information Systems
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• v.21 no.3
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• pp.117-129
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• 2015

As the Internet becomes ubiquitous, a large volume of information is posted on the Internet with exponential growth every day. Accordingly, it is not unusual that investors in stock markets gather and compile firm-specific or market-wide information through online searches. Importantly, it becomes easier for investors to acquire value-relevant information for their investment decision with the help of powerful search tools on the Internet. Our study examines whether or not the Internet helps investors assess a firm's value better by using firm-level data over long periods spanning from January 2004 to December 2013. To this end, we construct weekly-based search volume for information technology (IT) services firms on the Internet. We limit our focus to IT firms since they are often equipped with intangible assets and relatively less recognized to the public which makes them hard-to measure. To obtain the information on those firms, investors are more likely to consult the Internet and use the information to appreciate the firms more accurately and eventually improve their investment decisions. Prior studies have shown that changes in search volumes can reflect the various aspects of the complex human behaviors and forecast near-term values of economic indicators, including automobile sales, unemployment claims, and etc. Moreover, search volume of firm names or stock ticker symbols has been used as a direct proxy of individual investors' attention in financial markets since, different from indirect measures such as turnover and extreme returns, they can reveal and quantify the interest of investors in an objective way. Following this line of research, this study aims to gauge whether the information retrieved from the Internet is value relevant in assessing a firm. We also use search volume for analysis but, distinguished from prior studies, explore its impact on return comovements with market returns. Given that a firm's returns tend to comove with market returns excessively when investors are less informed about the firm, we empirically test the value of information by examining the association between Internet searches and the extent to which a firm's returns comove. Our results show that Internet searches are negatively associated with return comovements as expected. When sample is split by the size of firms, the impact of Internet searches on return comovements is shown to be greater for large firms than small ones. Interestingly, we find a greater impact of Internet searches on return comovements for years from 2009 to 2013 than earlier years possibly due to more aggressive and informative exploit of Internet searches in obtaining financial information. We also complement our analyses by examining the association between return volatility and Internet search volumes. If Internet searches capture investors' attention associated with a change in firm-specific fundamentals such as new product releases, stock splits and so on, a firm's return volatility is likely to increase while search results can provide value-relevant information to investors. Our results suggest that in general, an increase in the volume of Internet searches is not positively associated with return volatility. However, we find a positive association between Internet searches and return volatility when the sample is limited to larger firms. A stronger result from larger firms implies that investors still pay less attention to the information obtained from Internet searches for small firms while the information is value relevant in assessing stock values. However, we do find any systematic differences in the magnitude of Internet searches impact on return volatility by time periods. Taken together, our results shed new light on the value of information searched from the Internet in assessing stock values. Given the informational role of the Internet in stock markets, we believe the results would guide investors to exploit Internet search tools to be better informed, as a result improving their investment decisions.

• Journal of Intelligence and Information Systems
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• v.21 no.3
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• pp.19-36
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• 2015

Social media is an emerging issue in content services and in current business environment. YouTube is the most representative social media service in the world. YouTube is different from other conventional content services in its open user participation and contents creation methods. To promote a content in YouTube, it is important to understand the diffusion phenomena of contents and the network structural characteristics. Most previous studies analyzed impact factors of contents diffusion from the view point of general behavioral factors. Currently some researchers use network structure factors. However, these two approaches have been used separately. However this study tries to analyze the general impact factors on the view count and content based network structures all together. In addition, when building a content based network, this study forms the network structure by analyzing user comments on 22,370 contents of YouTube not based on the individual user based network. From this study, we re-proved statistically the causal relations between view count and not only general factors but also network factors. Moreover by analyzing this integrated research model, we found that these factors affect the view count of YouTube according to the following order; Uploader Followers, Video Age, Betweenness Centrality, Comments, Closeness Centrality, Clustering Coefficient and Rating. However Degree Centrality and Eigenvector Centrality affect the view count negatively. From this research some strategic points for the utilizing of contents diffusion are as followings. First, it is needed to manage general factors such as the number of uploader followers or subscribers, the video age, the number of comments, average rating points, and etc. The impact of average rating points is not so much important as we thought before. However, it is needed to increase the number of uploader followers strategically and sustain the contents in the service as long as possible. Second, we need to pay attention to the impacts of betweenness centrality and closeness centrality among other network factors. Users seems to search the related subject or similar contents after watching a content. It is needed to shorten the distance between other popular contents in the service. Namely, this study showed that it is beneficial for increasing view counts by decreasing the number of search attempts and increasing similarity with many other contents. This is consistent with the result of the clustering coefficient impact analysis. Third, it is important to notice the negative impact of degree centrality and eigenvector centrality on the view count. If the number of connections with other contents is too much increased it means there are many similar contents and eventually it might distribute the view counts. Moreover, too high eigenvector centrality means that there are connections with popular contents around the content, and it might lose the view count because of the impact of the popular contents. It would be better to avoid connections with too powerful popular contents. From this study we analyzed the phenomenon and verified diffusion factors of Youtube contents by using an integrated model consisting of general factors and network structure factors. From the viewpoints of social contribution, this study might provide useful information to music or movie industry or other contents vendors for their effective contents services. This research provides basic schemes that can be applied strategically in online contents marketing. One of the limitations of this study is that this study formed a contents based network for the network structure analysis. It might be an indirect method to see the content network structure. We can use more various methods to establish direct content network. Further researches include more detailed researches like an analysis according to the types of contents or domains or characteristics of the contents or users, and etc.

• Journal of Intelligence and Information Systems
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• v.16 no.3
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• pp.99-120
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• 2010

Due to the wide spread of customers' frequent access of non face-to-face services, there have been many attempts to improve customer satisfaction using huge amounts of data accumulated throughnon face-to-face channels. Usually, a call center is regarded to be one of the most representative non-faced channels. Therefore, it is important that a call center has enough agents to offer high level customer satisfaction. However, managing too many agents would increase the operational costs of a call center by increasing labor costs. Therefore, predicting and calculating the appropriate size of human resources of a call center is one of the most critical success factors of call center management. For this reason, most call centers are currently establishing a department of WFM(Work Force Management) to estimate the appropriate number of agents and to direct much effort to predict the volume of inbound calls. In real world applications, inbound call prediction is usually performed based on the intuition and experience of a domain expert. In other words, a domain expert usually predicts the volume of calls by calculating the average call of some periods and adjusting the average according tohis/her subjective estimation. However, this kind of approach has radical limitations in that the result of prediction might be strongly affected by the expert's personal experience and competence. It is often the case that a domain expert may predict inbound calls quite differently from anotherif the two experts have mutually different opinions on selecting influential variables and priorities among the variables. Moreover, it is almost impossible to logically clarify the process of expert's subjective prediction. Currently, to overcome the limitations of subjective call prediction, most call centers are adopting a WFMS(Workforce Management System) package in which expert's best practices are systemized. With WFMS, a user can predict the volume of calls by calculating the average call of each day of the week, excluding some eventful days. However, WFMS costs too much capital during the early stage of system establishment. Moreover, it is hard to reflect new information ontothe system when some factors affecting the amount of calls have been changed. In this paper, we attempt to devise a new model for predicting inbound calls that is not only based on theoretical background but also easily applicable to real world applications. Our model was mainly developed by the interactive decision tree technique, one of the most popular techniques in data mining. Therefore, we expect that our model can predict inbound calls automatically based on historical data, and it can utilize expert's domain knowledge during the process of tree construction. To analyze the accuracy of our model, we performed intensive experiments on a real case of one of the largest car insurance companies in Korea. In the case study, the prediction accuracy of the devised two models and traditional WFMS are analyzed with respect to the various error rates allowable. The experiments reveal that our data mining-based two models outperform WFMS in terms of predicting the amount of accident calls and fault calls in most experimental situations examined.

• Journal of radiological science and technology
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• v.27 no.2
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• pp.35-43
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• 2004

Radioprotective effects of ginseng extracts on liver damage induced by high energy x-ray were studied. To one group of ICR male mice were given white(50 mg/kg/day for 7days, orally) and fermenta ginseng extracts(500 mg/kg/day for 7days, orally) before irrdiation. To another group were irradiated by 5 Gy dose of high energy x-ray. Contrast group were given with saline(0.1 ml). This study also investigated the radioprotective effect between SOD, CAT, hydrogen peroxide and ginseng extracts on hepatic damage. This study measured the level of superoxide dismutase(SOD), catalase(CAT), hydrogen peroxide($H_2O_2$) in liver tissue. Administrating orally white (50 mg/kg/day for 7days, orally) and fermenta ginseng extracts(500 mg/kg/day), the activity of SOD, CAT were generally increased and the hydrogen peroxide($H_2O_2$) was decreased. After irradiation, the activity of SOD, CAT were generally decreased and the hydrogen peroxide($H_2O_2$) was increased. Therefore, ginseng extracts increased antioxidative enzyme activity. And We know that the antioxidatant effect of extracts from white and fermenta ginseng protect radiation damage by direct antioxidant effect involving SOD, CAT. It was included that ginseng can protect against radiation damage through its antioxidatant properties.

• Journal of radiological science and technology
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• v.36 no.2
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• pp.99-110
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• 2013

In the medical field, the necessity of education growth for the professional Radiation Technologists has been emphasized to become experts on radiation and the radiation field is important of the society. Also, in hospitals and companies, important on thesis is getting higher in order to active and cope with rapidly changing internal and external environment and a more in-depth expert training, the necessity of new teaching and learning model that can cope with changes in a more proactive has become. Thesis writing classes brought limits to the in-depth learning as to start a semester and rely on only specific programs besides, inevitable on passive participation. In addition, it does not have a variety opportunity to present, an actual opportunity that can be written and discussed does not provide much caused by instructor-led classes. As well as, it has had a direct impact on the quality of the thesis, furthermore, having the opportunity to participate in various conferences showed the limitations. In order to solve these problems, in this study, writing thesis has organized training operations as a consistent gradual deepening of learning, at the same time, the operational idea was proposed based on the connectivity integrated operating and effective training program & instructional tool for improving the ability to perform the written actual thesis. The development of teaching and learning model consisted of 4 system modeling, scaffolding, articulation, exploration. Depending on the nature of the course, consisting team following the personal interest and the topic allow for connection subject, based on this, promote research capacity through a step-by-step evaluation and feedback and, fundamentally strengthen problem-solving skills through the journal studies, help not only solving the real-time problem by taking wiki-space but also efficient use of time, increase the quality of the thesis by activating cooperation through mentoring, as a result, it was to promote a positive partnership with the academic. Support system in three stages planning subject, progress & writing, writing thesis & presentation and based on cognitive apprenticeship. The ongoing Coaching and Reflection of professor and expert was applied in order to maintain these activities smoothly. The results of this study will introduce actively, voluntarily and substantially join to learners, by doing so, culture the enhancement of creativity, originality and the ability to co-work and by enhance the expertise of based-knowledge, it is considered to be help to improve the comprehensive ability.

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.270-285
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• 2020

This study examines the state of archeological research on Silla and Unified Silla conducted in North Korea and identifies its characteristics. In South Korea, most research has focused on prehistoric times in North Korea, and little research has been done on Silla and Unified Silla. Noting this, we attempted to examine the history of archaeological research in North Korea to provide foundations upon which to go forward. The research was examined in terms of general archaeological themes including tombs, fortresses, the capital city, earthenware, roof tiles, ornaments, weapons, and horse harnesses, and we identified four characteristics from the examination. First, Juche ideology had a great influence on interpretation of the unification of the three kingdoms. The Juche ideology was first proposed in 1955, and at the time, it was not fully established as an ideology but rather seen as constituting opposition to toadyism. Accordingly, the unification of the three kingdoms led by Silla was seen as amounting to collusion with foreign forces and was not acknowledged. A piece of evidence shows that this change took place around 1962. Second, an inclination to testify to the 'uniqueness' of the cultures of the three kingdoms is observed. The argument is that culture in the Korean peninsula has unique characteristics that set it apart from Chinese culture, and that the cultures of the three kingdoms share much in common. This inclination was not mentioned in research until the 1950s, and it can be seen as an effort to comply with Juche ideology and prove the principle of unity as stated in the national leader's instructions in the 1960s. Third, the influence of Goguryeo on the formation of Silla culture is emphasized. Related research explains that Baekje, Silla, and Gaya adopted the 'superior' culture of Goguryeo, and could establish 'uniqueness' of culture accordingly. It is claimed that an advanced Goguryeo culture was disseminated throughout Balhae and Unified Silla, and then to Goryeo, resulting in a true unification of the ethnic culture. Fourth, researchers in North Korea presume the Silla tombs and other relics to be far older than South Korean researchers' estimate. From a standpoint of highlighting the long history of Korea, they estimate the Silla Dynasty was founded in the early or mid-first century. Accordingly, archeological evidence that demonstrates the establishment of the state is dated as far back. Such an estimate is also indispensable in justifying the explanation that the chamber tombs of Goguryeo had a direct influence on Silla. These research characteristics which arose during the 1960s continue to be basic guidelines for North Korean researchers.

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.204-221
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• 2020

East Asian countries share a culture of perfuming clothes. The prosperity of the Maritime Silk Road and the incense trade are direct factors that have led to the development of incense culture. Perfuming clothes is a method of applying fragrance by burning incense. The Chinese could make an incense mixture with various types of incense, and records demonstrating use of perfuming clothes tools (熏籠) show that they might have perfumed clothes with incense mixtures. During the Tang dynasty, the incense trade thrived. Examples of ancient literature such as 『千金要方』, 『香譜』, 『香乘』 describe how to make incense for perfuming clothes and how to perfume clothes. 『桂海虞衡志』 and 『諸蕃志』 shows trade partners and goods. Incense was introduced to Korea alongside Buddhist culture. 『買新羅物解』 shows Silla traded incense with Japan. One of the trade goods recorded in 『買新羅物解』 is perfuming cloth incense (熏衣香), which establishes that Silla performed perfuming clothes at that time. During the Goryeo dynasty, Goryeo exported musk as well as ginseng. The royal family burned incense from the Song royal family. Noblewomen preferred sachets. The use of this dress continued into the Joseon dynasty. 『買新羅物解』 showed that Japan imported incense from Silla. 『The tale of Genji』 illustrates Heian nobles' incense culture, perfuming clothes culture, and trade of incense. Perfuming clothes tools became essential articles for marriage purposes and it developed in a practical shape. The Champa had a perfuming clothes culture. It is described on 『諸蕃志』. As Agilawood is found in Tongking, and Tongking was neighbor to the Champa and China, they might have had a perfuming clothes culture as well. Korea, China, Japan, and Vietnam shared a perfuming clothes culture. We can identify universality and commonality in the purpose of perfuming clothes, time of development, the method of making the incense mixture for perfuming clothes, the method of perfuming clothes, the tools, the gender of perfumer, and the type of herbs and spices.