• Title/Summary/Keyword: eigenvector

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Further Investigations on the Financial Characteristics of Credit Default Swap(CDS) spreads for Korean Firms (국내기업들의 신용부도스왑(CDS) 스프레드의 재무적 특성에 관한 심층분석 연구)

  • Kim, Han-Joon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.9
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    • pp.3900-3914
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    • 2012
  • This study examined the background of the recent global financial crisis and the concept of one of the financial derivatives such as the credit default swap(CDS) or synthetic CDO(collateral debt obligations), given the rapid growing and changing the over-the-counter derivative markets in their volume and structures. In comparison with the previous literature such as the study of Park & Kim (2011), this research empirically performed more thorough and comprehensive investigations to find any financial characteristics or attributes to determine the CDS spreads. Regarding the results obtained from the multiple regression models, the explanatory variables such as STYIELD3, SLOPE, INASSETS, and VOLATILITY, showed their statistically significant effects on all the tested dependent variables(DVs). Another procedure such as the principle component analysis(PCA), was also performed to account for additional IDVs as possible determinants of the dependent variables. Subsequent to this analysis, larger coefficients of each corresponding eigenvector such as BETA, PFT2, GROWTH, STD, and BLEVERAGE were found to be possible financial determinants. For robustness, all the IDVs were employed to be tested in the 'full' regression model with stepwise procedure. As a result, STYIELD3, SLOPE, and VOLATILITY, and BETA showed their statistically significant relationship with all the dependent variables of the CDS spreads.

A Study on the Relationship between Cooperation Network and Publication Performance of Korean Government-Funded Research Institutes through Collaborative Paper Status (공동논문 현황을 통한 정부출연(연)의 협력네트워크 구조와 논문성과와의 관계 분석)

  • Chung, Taewon;Chung, Dongsub;Kim, JeongHeum
    • Journal of Korea Technology Innovation Society
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    • v.17 no.1
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    • pp.242-263
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    • 2014
  • Establishment of efficient cooperative ecosystem of research institutes is important for the efficiency of national innovation system, especially in the era of technology convergence. Performance of institutes inside the ecosystem is dependent on the position of the institutes in the system. This study investigates the relationship between network structure and research performance, and determines significant factors on the research performance. The results of 5 year panel data analysis of SCI journal papers of Korean government research institutes indicate that four network centralities -degree, betweenness, closeness, and eigenvector- and structural holes have significant effect on the research performance of the institutes. Among the four centralities, closeness and eigenvectors are more significant than others. Implications of the results of this study for policy of establishing efficient cooperative system are that increasing the cooperative activities of less active institutes is more effective for research performance than increasing the magnitude of cooperative activities of all institutes. Also, when an institute starts a new cooperative relationship, it is better to have relationship with an active institute first.

Analyzing Comments of YouTube Video to Measure Use and Gratification Theory Using Videos of Trot Singer, Cho Myung-sub (YouTube 동영상 의견분석을 통한 사용과 충족 이론 측정 : 트로트 가수 조명섭 동영상을 중심으로)

  • Hong, Han-Kook;Leem, Byung-hak;Kim, Sam-Moon
    • The Journal of the Korea Contents Association
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    • v.20 no.9
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    • pp.29-42
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    • 2020
  • The purpose of this study is to present a qualitative research method for extracting and analyzing the comments written by YouTube video users. To do this, we used YouTube users' feedback to measure the hedonic, social, and utilitarian gratification of use and gratification theory(UGT) through by using analysis and topic modeling. The result of the measurement found that the first reason why users watch the trot singer, Cho Myung-sub's video in the KBS Korean broadcasting channel is to achieve hedonic gratification with high frequency. In word-document network analysis, the degree of centrality was high in words, such as 'cheering', 'thank you', 'fighting', and 'best'. Betweenness centrality is similar to the degree of centrality. Eigenvector centrality also shows that words such as 'love', 'heart', and 'thank you' are the most influential words of users' opinions. The results of the centrality analysis present that the majority of video users show their 'love', 'heart' and 'thank you' for the video. it indicates that the high words in centrality analysis is consistent with the high frequency words of hedonic and social gratification dimension of the UGT. The study has research methodological implication that shed light on the motivations for watching YouTube videos with UGT using text mining techniques that automate qualitative analysis, rather than following a survey-based structural equation model.

Response of Soil Microbial Communities to Different Cultivation Systems in Controlled Horticultural Land

  • Lee, You-Seok;Kang, Jeong-Hwa;Choi, Kyeong-Ju;Lee, Seong-Tae;Kim, Eun-Seok;Song, Won-Doo;Lee, Young-Han
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.1
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    • pp.118-126
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    • 2011
  • Ester-linked fatty acid methyl ester (EL-FAME) profiles were used to describe differences in soil microbial communities influenced by conventional farming system (CFS), and organic farming system (OFS) in controlled horticultural land. Soil physicochemical properties and soil microbial communities were determined in the experimental fields. Higher organic matter content in OFS reduced soil bulk density which in turn increased the soil porosity. Generally, soil chemical properties in OFS were higher than those of CFS, but EC value in OFS was significantly lower than that of CFS. With the exception of Fe content, other macronutrient contents and pH in both farming system decreased with the soil depth. Soil microbial biomass of OFS was approximately 1.3 times in topsoil and 1.8 times in subsoil higher than those of CFS. Lower ratios of cy17:0 to $16:1{\omega}7c$ and cy19:0 to $18:1{\omega}7c$ were found in the CFS soils than the OFS soils, indicating that microbial stress decreased. The ratio of MUFA to SFA was higher in OFS due to organic input to the soil. In principal components analysis (PCA), the first variable accounted for 54.3%, while the second for 27.3%, respectively. The PC1 of the PCA separated the samples from CFS and OFS, while the PC2 of the PCA separated the samples from topsoil and subsoil. EL-FAMEs with the positive eigenvector coefficients for PC1 were cy17: 0 to $16:1{\omega}7c$ ratio, cy19:0 to $18:1{\omega}7c$ ratio, soil pH, soil organic matter, and soil $NO_3$-N content. Our findings suggest that the shifting cy19:0 to $18:1{\omega}7c$ ratio should be considered as potential factors responsible for the clear microbial community differentiation observed between different cultivation systems and soil depth in controlled horticultural land.

Semi-Empirical MO Calculations on ${\pi}$-Nonbonded and ${\sigma}$-Conjugative Interactions (반경험적 분자궤도함수 계산법에 의한 ${\pi}$-비결합 및 ${\sigma}$-컨쥬게이션 상호작용에 관한 연구)

  • Ikchoon Lee;Young Gu Cheun;Kiyull Yang;Wang Ki Kim
    • Journal of the Korean Chemical Society
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    • v.26 no.4
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    • pp.195-204
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    • 1982
  • Semi-empirical MO calculations, EHT, CNDO/2, MINDO/3, and MNDO met hods, were performed on various geometries of n-butane, n-alkyl radical and tetramethylene diracal (triplet) in order to compare eigenvalue and eigenvector properties with those obtained by STO-3G method. All methods predicted the same relative order of stabilities of various geometries for n-butane; geometrical preferences were found to be dominated by one-electron factor, ${\pi}$-orbital energy changes being more impotant in the semi-empirical methods. The hyperconjugative energy changes accompanying structural changes from $(n-{\sigma}{\ast})_{trans}$ to (n-{\sigma}{\ast})cis were underestimated in the EHT, CNDO/2 and MINDO/3, whereas those were overestimated in the MNDO. The net destabilizing effect of $(n-{\sigma}{\ast})_{trans}$ structure was mainly due to the large internuclear energy involved in the structure. Through-space interaction between $n_1$ and $n_2$ orbitals of diradical caused energy gap narrowing of ${\Delta}E_{sp}$ and ${\Delta}{\varepsilon}={\varepsilon}_0$-${\varepsilon}_{av}$; through-space interaction had opposing effect to that of through-bond interaction. Due to the less severe neglect of differential overlaps in the MNDO, this energy gap narrowing effect appeared amplified in the MNDO. In general orbital properties were found to be reproduced satisfactorily, but eigenvalue properties were not, in all the semi-empirical methods especially when ${\sigma}-{\sigma}{\ast}$ and n-$n-{\sigma}{\ast}$interactions were involved.

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Adaptable Center Detection of a Laser Line with a Normalization Approach using Hessian-matrix Eigenvalues

  • Xu, Guan;Sun, Lina;Li, Xiaotao;Su, Jian;Hao, Zhaobing;Lu, Xue
    • Journal of the Optical Society of Korea
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    • v.18 no.4
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    • pp.317-329
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    • 2014
  • In vision measurement systems based on structured light, the key point of detection precision is to determine accurately the central position of the projected laser line in the image. The purpose of this research is to extract laser line centers based on a decision function generated to distinguish the real centers from candidate points with a high recognition rate. First, preprocessing of an image adopting a difference image method is conducted to realize image segmentation of the laser line. Second, the feature points in an integral pixel level are selected as the initiating light line centers by the eigenvalues of the Hessian matrix. Third, according to the light intensity distribution of a laser line obeying a Gaussian distribution in transverse section and a constant distribution in longitudinal section, a normalized model of Hessian matrix eigenvalues for the candidate centers of the laser line is presented to balance reasonably the two eigenvalues that indicate the variation tendencies of the second-order partial derivatives of the Gaussian function and constant function, respectively. The proposed model integrates a Gaussian recognition function and a sinusoidal recognition function. The Gaussian recognition function estimates the characteristic that one eigenvalue approaches zero, and enhances the sensitivity of the decision function to that characteristic, which corresponds to the longitudinal direction of the laser line. The sinusoidal recognition function evaluates the feature that the other eigenvalue is negative with a large absolute value, making the decision function more sensitive to that feature, which is related to the transverse direction of the laser line. In the proposed model the decision function is weighted for higher values to the real centers synthetically, considering the properties in the longitudinal and transverse directions of the laser line. Moreover, this method provides a decision value from 0 to 1 for arbitrary candidate centers, which yields a normalized measure for different laser lines in different images. The normalized results of pixels close to 1 are determined to be the real centers by progressive scanning of the image columns. Finally, the zero point of a second-order Taylor expansion in the eigenvector's direction is employed to refine further the extraction results of the central points at the subpixel level. The experimental results show that the method based on this normalization model accurately extracts the coordinates of laser line centers and obtains a higher recognition rate in two group experiments.

Development of a groundwater contamination potential evaluation technique by improving DRASTIC Index for a tunnel excavation area (개선된 DRASTIC 기법을 이용한 터널굴착 예정지역의 지하수 오염 가능성 평가기법 개발에 관한 연구)

  • Park, Jun-Kyung;Park, Young-Jin;Wye, Yong-Gon;Choi, Young-Tae;Lee, Han-Min
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.5 no.1
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    • pp.71-88
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    • 2003
  • The DRASTIC system is widely used for assessing regional groundwater pollution susceptibility by using hydrogeological factors such as depth to water, net recharge, aquifer media, soil media, topography, vadose zone media, hydraulic conductivity. This study is providing Modified Drastic Model to which lineament density, land use, influence of groundwater drawdown caused by tunnel excavation are added as additional factors using geographic information system, and then to evaluate groundwater contamination potential of ${\bigcirc}{\bigcirc}$ area. For statistical analysis, vector coverage per each factor is converted to grid layer and after each correlation coefficient between factors, covariance, variance, eigenvalue and eigenvector by principal component analysis of 3 direction, are calculated, correlation between factors is analyzed. Also after correlation coefficients between general DRASTIC layer and rated lineament density layer, between general DRASTIC layer and rated land use layer, between general DRASTIC layer and rated tunnel excavation influence layer are calculated, final modified DRASTIC model is constructed by using them with each weighting. When modified DRASTIC model was compared with general DRASTIC model, contamination potential in modified DRASTIC model is fairly detailed and consequently, vulnerable area which has high contamination potential could be presented concretly.

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Software development for the visualization of brain fiber tract by using 24-bit color coding in diffusion tensor image

  • Oh, Jung-Su;Song, In-Chan;Ik hwan Cho;Kim, Jong-Hyo;Chang, Kee-Hyun;Park, Kwang-Suk
    • Proceedings of the KSMRM Conference
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    • 2002.11a
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    • pp.133-133
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    • 2002
  • Purpose: The purpose of paper is to implement software to visualize brain fiber tract using a 24-bit color coding scheme and to test its feasibility. Materials and Methods: MR imaging was performed on GE 1.5 T Signa scanner. For diffusion tensor image, we used a single shot spin-echo EPI sequence with 7 non-colinear pulsed-field gradient directions: (x, y, z):(1,1,0),(-1,1,0),(1,0,1),(-1,0,1),(0,1,1),(0,1,-1) and without diffusion gradient. B-factor was 500 sec/$\textrm{mm}^2$. Acquisition parameters are as follows: TUTE=10000ms/99ms, FOV=240mm, matrix=128${\times}$128, slice thickness/gap=6mm/0mm, total slice number=30. Subjects consisted of 10 normal young volunteers (age:21∼26 yrs, 5 men, 5 women). All DTI images were smoothed with Gaussian kernel with the FWHM of 2 pixels. Color coding schemes for visualization of directional information was as follows. HSV(Hue, Saturation, Value) color system is appropriate for assigning RGB(Red, Green, and Blue) value for every different directions because of its volumetric directional expression. Each of HSV are assigned due to (r,$\theta$,${\Phi}$) in spherical coordinate. HSV calculated by this way can be transformed into RGB color system by general HSV to RGB conversion formula. Symmetry schemes: It is natural to code the antipodal direction to be same color(antipodal symmetry). So even with no symmetry scheme, the antipodal symmetry must be included. With no symmetry scheme, we can assign every different colors for every different orientation.(H =${\Phi}$, S=2$\theta$/$\pi$, V=λw, where λw is anisotropy). But that may assign very discontinuous color even between adjacent yokels. On the other hand, Full symmetry or absolute value scheme includes symmetry for 180$^{\circ}$ rotation about xy-plane of color coordinate (rotational symmetry) and for both hemisphere (mirror symmetry). In absolute value scheme, each of RGB value can be expressed as follows. R=λw|Vx|, G=λw|Vy|, B=λw|Vz|, where (Vx, Vy, Vz) is eigenvector corresponding to the largest eigenvalue of diffusion tensor. With applying full symmetry or absolute value scheme, we can get more continuous color coding at the expense of coding same color for symmetric direction. For better visualization of fiber tract directions, Gamma and brightness correction had done. All of these implementations were done on the IDL 5.4 platform.

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Research Trends of Studies Related to the Geological Fieldwork Using Semantic Network Analysis: Focused on the Last 21 Years(2000-2020) (언어 네트워크를 이용한 야외지질답사 관련 연구 동향 분석: 최근 21년(2000~2020년)을 중심으로)

  • Jeong, Dong-Gwon
    • Journal of the Korean Society of Earth Science Education
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    • v.14 no.2
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    • pp.173-192
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    • 2021
  • The purpose of this study is to analyze the previous research on geological fieldwork from 2000 to 2020, examine the tasks that have been focused on, and suggest directions and implications for future geological fieldwork research. The data was conducted for the thesis searched on ScienceON and RISS in relation to geological fieldwork and journals listed in the Korean Citation Index(KCI), and the study title was analyzed using the semantic network analysis. For analysis, the data that had been pre-processed was visualized as a network by semantic network analysis, and frequency and centrality were analyzed. The centrality analysis was based on degree centrality and eigenvector centrality, and all analyzes were performed by dividing the entire study period into four periods: 2000-2005, 2006-2010, 2011-2015, and 2016-2020. As a result, research on geological fieldwork focused more on the development of geological field courses, and in particular, jeju island was actively discussed as a learning site. Also, the study was conducted on students rather than teachers, and among them, high school students showed high frequency and centrality. In addition, it can be seen that studies on the educational effect of geological fieldwork were discussed, either in connection with programs such as STEAM, free-semester program, or indirect geological fieldwork methods such as web, flash panorama, and 3D. This study is meaningful in that it suggests the direction of future research by looking back on the research on geological fieldwork that has been done so far.

A Study on Changes in the Centrality Movement of Coastal Shipping Passengers Utilizing the SNA Method (SNA 방법을 통한 연안해운 승객 중심성 이동변화 분석)

  • PARK, Sung-hun;JU, Dong-young;OH, Jae-gyun;NAM, Tae-hyun;YEO, Gi-tae
    • The Journal of shipping and logistics
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    • v.34 no.4
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    • pp.527-544
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    • 2018
  • In this study, SNA analysis was conducted to examine changes in passenger movements in domestic coastal shipping. The validity of derivation of centrality rankings was enhanced by using the connection centrality that reflected weights, which had not been applied in previous research. The results of the connection centrality analysis indicated that the network composition ratio of the South Sea region was high, and the results of analysis of betweenness centrality indicated that ports belonging to the South Sea region recorded high ranks. Jeju Island, which acts as a gateway to the West Sea and the South Sea, Mokpo, which acts as a gateway between the land and islands, those ports that are geographically close to the land, and those ports that are smoothly connected to small ports, were shown to have betweenness centrality. Meanwhile, in the results of analysis of eigenvector centrality, not only ports in the South Sea region but also many ports in the West Sea region were included in the high ranked ones. Using these results, the port authority can identify major ports in domestic coastal shipping, determine the priorities support, identify the current situation of the port connection relations, and establish strategies for management of key development areas. As future studies, studies in the aspect of economy that separate general passengers and island passengers and utilize data such as fares, distances, and time are necessary.