• 제목/요약/키워드: Non-parametric Test

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An Empirical Study on the Relationship between Corporate and Radical Innovation based on Patent Information (특허 정보를 이용한 기업의 급진적 혁신에 관한 실증연구)

  • Jeon, Suyeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.10
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    • pp.471-479
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    • 2020
  • In this paper, we analyze features of radical innovative businesses using their patents. Although patents have been used to evaluate outcomes of businesses from the 1980s, it is challenging to use patents for radical innovations. We examined the possibility of taking advantage of patents for an indicator that represents a radical innovation in pharmaceutical industry. To this end, we collected FDA approval data from the U.S. Food and Drug Administration and patent data of 18 pharmaceutical companies. For analysis, we utilized the network centrality analysis and Wilcoxon signed ranked test, which is a non-parametric statistical hypothesis test used to compare two related samples. We observed that a radical innovative company typically cooperates with other research groups, such as universities and companies, and acts as a hub for connectivity in pharmaceuticals. Also, we found that there are differences in centrality between radical firms and non-radical firms. Thus, we expect that the results of this study will help in developing strategies for research and development of pharmaceutical companies and identifying factors affecting radical innovation in the future.

Trend Detection of Serially Correlated Hydrologic Series (상관성을 가진 시계열 자료의 경향성 분석에 관한 연구)

  • Oh, Je Seung;Kim, Byung Sik;Kim, Hung Soo;Seoh, Byung Ha
    • Journal of Wetlands Research
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    • v.6 no.4
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    • pp.35-43
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    • 2004
  • The non-parametric Mann-Kendall(MK) statistical test has been widely used to assess the significance of trend in hydrologic time series. The test requires sample data should be serially independent. If sample data is serially correlated, the presence of serial correlation in a time series will affect the test ability for trend analysis. So, we would like to use the modified MK test which uses the effective sample size(ESS) to eliminate the effect of serial correlation in a series. This study investigates the ability of ESS to eliminate the influence of serial correlation of MK test by Monte Carlo simulation and by real series. As the results, MK test shows the increase of trend rate as the serial correlation is increased but the modified MK test shows ESS can eliminate the serial correlation for trend analysis. Therefore we confirmed the modified MK test is a very useful tool for trend analysis.

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Do Firm Characteristics and Industry Matter in Determining Corporate Cash Holdings? Evidence from Hospitality Firms

  • KWAN, Jing-Hui;LAU, Wee-Yeap
    • The Journal of Asian Finance, Economics and Business
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    • v.7 no.2
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    • pp.9-20
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    • 2020
  • The study investigates a recent surge of cash literature by using a sample of hospitality firms to gain a new understanding of corporate cash holdings. Past literature states that there is a substantial variation of liquidity across industry groups. Existing literature predominantly refers to US-listed firms and focus on either hotels or restaurants and not the hospitality industry as a whole. Therefore, we provide a comparative study of cash holdings behaviour between hospitality and non-hospitality firms from an emerging market context. Using a sample of public listed hospitality firms from 2002 to 2013, dynamic panel regression techniques are used to study the relationships between firm characteristics and cash levels. Also, the non-parametric Wilcoxon-Mann-Whitney test was carried out to examine the time and sectoral differences in cash holdings. In addition, the panel regression techniques are used to investigate the relationships between firm characteristics and level of corporate cash holdings. The results reveal that firm characteristics do matter in hospitality firms. We find that firm size, capital expenditures, and liquid assets substitutes are negatively related to cash level. The results support trade-off theory and the pecking order theory. This study incrementally explains the cash holdings behaviour of hospitality firms in emerging market.

Modelling and classification of tubular joint rigidity and its effect on the global response of CHS lattice girders

  • Wang, Wei;Chen, Yiyi
    • Structural Engineering and Mechanics
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    • v.21 no.6
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    • pp.677-698
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    • 2005
  • In engineering practice, tubular connections are usually assumed pinned or rigid. Recent research showed that tubular joints may exhibit non-rigid behavior under axial or bending loads. This paper is concerned with establishing a new classification for tubular joints and investigating the effect of joint rigidity on the global behavior of CHS (Circular Hollow Section) lattice girders. Parametric formulae for predicting tubular joint rigidities are proposed, which are based on the finite element analyses through systematic variation of the main geometric parameters. Comparison with test results proves the reliability of these formulae. By considering the deformation patterns of respective parts of Vierendeel lattice girders, the boundary between rigid and semirigid tubular connections is built in terms of joint bending rigidity. In order to include characteristics of joint rigidity in the global structural analysis, a type of semirigid element which can effectively reflect the interaction of two braces in K joints is introduced and validated. The numerical example of a Warren lattice girder with different joint models shows the great effect of tubular joint rigidities on the internal forces, deformation and secondary stresses.

A Study on the Factors Affecting Self-Regulation Program for the Hypertensives in Rural Area (농촌지역 고혈압 환자를 위한 자기조절 프로그램 관련 요인 연구)

  • Park, Young-Im;Jun, Myung-Hee
    • Research in Community and Public Health Nursing
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    • v.12 no.1
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    • pp.202-213
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    • 2001
  • This study was conducted to identify the changes of the relationship among general characteristics, self-efficacy. and self-care of the hypertensives in rural area. For this purpose, self-regulation program was carried at two Community Health Practitioner Post located in the suburbs of Daejeon City from September to November. 1999. Data were analyzed with non-parametric statistics, t-test, pearson correlation. The results were as follows; 1. The level of self-care was significantly different according to sex, status of smoking, and the level of self-efficacy of non-smoker was significantly higher than smoker. 2. After self-regulation program, there were significant positive relationship among self-efficacy, self-care, internal locus control, and negative relationship between perceived barrier and self-care. From these results, it can be concluded that the self-regulation program is an effective nursing strategy to promote self-care performance of hypertensives in rural area, and this program can be recommended for the management of hypertensives.

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Investigation of Effect of Input Ground Motion on the Failure Surface of Mountain Slopes

  • Khalid, Muhammad Irslan;Pervaiz, Usman;Park, Duhee
    • Journal of the Korean GEO-environmental Society
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    • v.22 no.7
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    • pp.5-12
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    • 2021
  • The reliable seismic stability evaluation of the natural slopes and geotechnical structures has become a critical factor of the design. Pseudo-static or permanent displacement methods are typically employed to evaluate the seismic slope performance. In both methods, the effect of input ground motion on the sliding surface is ignored, and failure surface from the limit equilibrium method is used. For the assessment of the seismic sensitivity of failure surface, two-dimensional non-linear finite element analyses are performed. The performance of the finite element model was validated against centrifuge measurements. A parametric study with a range of input ground motion was performed, and numerical results were used to assess the influence of ground motion characteristics on the sliding surface. Based on the results, it is demonstrated that the characteristics of input ground motion have a significant influence on the location of the seismically induce failure surface. In addition to dynamic analysis, pseudo-static analyses were performed to evaluate the discrepancy. It is observed that sliding surfaces developed from pseudo-static and dynamic analyses are different. The location of the failure surface change with the amplitude and Tm of motion. Therefore, it is recommended to determine failure surfaces from dynamic analysis

Implementation of contextualized, emergency management cognitive aids in a periodontics clinic

  • Siemens, Mikaela J.;Rice, Andi N.;Jensen, Trenton F.;Simmons (Muckler), Virginia C.
    • Journal of Dental Anesthesia and Pain Medicine
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    • v.21 no.3
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    • pp.227-236
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    • 2021
  • Background: Emergencies in outpatient clinics are rare. However, potentially catastrophic events can be challenging to manage due to a variety of factors, including limited equipment and staff. The purpose of this quality improvement project was to improve the staff knowledge and familiarity with critical performance elements for emergencies encountered in the setting of a periodontics clinic. Methods: Emergency cognitive aids tailored to the clinic's resources were created for anaphylaxis, airway obstruction, and sublingual hemorrhage. The project pre-post-test repeated measures design evaluated the effectiveness of cognitive aids using a combination of hands-on simulation, written knowledge assessments, and self-efficacy surveys. Training sessions and simulations were provided to the clinic's existing care teams made up of a periodontist and two dental assistants with an anesthetist who was present for simulations involving sedation. Due to the small sample size (N = 14) and non-normal distribution, all metrics were evaluated using non-parametric statistics. Results: Significant improvements were found in knowledge assessment (-2.310, P = 0.021) and self-efficacy (-2.486, P = 0.013) scores when retention after a training session before and after the introduction of cognitive aid was compared. The mean simulation scores and times improved steadily or reached maximum scores during the project progression. Conclusion: Training sessions before and after cognitive aid introduction were effective in improving knowledge, self-efficacy, and simulation performance. Future projects should focus on validating the process for creating contextualized cognitive aids and evaluating the effectiveness of these cognitive aids in larger samples.

The Analysis of Difference in Awareness and Needs of Social Communication of Guardians Caring for Adolescent with Development Disorders Adolscents (발달장애 청소년 양육자의 사회적 의사소통 인식과 요구도 차이 분석)

  • Park, Hyun;Lee, Myung-Soon
    • The Journal of the Korea Contents Association
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    • v.18 no.8
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    • pp.561-572
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    • 2018
  • This study the awareness and the demands of the parents on the communication level for social participation of the youth with developmental disability were identified and investigated the relation on client's age, detection time of the condition, disability grades, handicapped types, speech therapy period. For the non-parametric test, Man-Whitney U test, and Kruskal-Wallis test were performed and for post-hoc test, Scheffe test was performed. The results of this study was that the significant difference was found in the awareness and the demand of the communication level of the youth with developmental disability according to the age of children, time of discovery, disability grade, type of disability and speech therapy period. In conclusion, the speech therapy for the youth with developmental disability should be made in the dimension of communication for the purpose of social participation. The follow-up research to emphasize the social support and the institutional backup will be required.

Effect of STEL-toluene on Metabolism of Benzene in Rats (단시간 허용농도의 toluene이 benzene대사에 미치는 영향)

  • Roh, Jae-Hoon;Shin, Dong-Chun;Park, Jung-Gyun;Moon, Young-Hahn;Chung, Ho-Keun
    • Journal of Preventive Medicine and Public Health
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    • v.21 no.1 s.23
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    • pp.152-162
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    • 1988
  • Benzene and toluene, which are widely used aromatic hydrocarbons in workplace, are recently proved to cause health hazards due to their toxic effects. This study investigated the influence of toluene on the urinary excretion of benzene metabolite by administering short term exposure limit(STEL) of these compounds(i.e., 13.8mg/kg of benzene and 108.8 mg/kg of toluene) intraperitoneally into Sprague-Dawley rats. After administration, urinary phenol concentration of rat was measured by gas chromatography for every three hours. Data were analyzed by non-parametric statistical methods using Kruskal-Wallis multi-sample test and Mann-Whitney U test. The following results were obtained : 1. Administration of STEL-benzene increased urinary phenol concentration in lats. 2. Urinary phenol concentration was increased logarithmically according to the dosage of benzene. 3. Excretion of phenol in urine was decreased when benzene and toluene were administered simultaneously compared with administering benzene alone. In summary, these results reveal that administration of STEL of toluene has antagonistic effect of urinary excretion of benzene metabolite in rats.

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Compressive Behavior for Smart Skin of Sandwich Structure (스마트 스킨 샌드위치 시편의 압축거동 연구)

  • Kim, Young-Sung;Kim, Yong-Bum;Park, Hoon-Cheol;Yoon, Kwang-Joon;Lee, Jeo-Hwa
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.8
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    • pp.56-64
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    • 2002
  • In this work, a smart skin of multi-layer structure is designed and manufactured. Through the compression test, the characteristic of smart skin behavior was examined. We have predicted stress of each layer and the first failed layer of the smart skin structure by using MSC/NASTRAN. The finite element model was verified by comparing measured data from the compression test and result from the geometrically linear/non-linear analysis. The finite element model was used for obtaining design data from the parametric study. It was confirmed that shear moduli of honeycomb core affect the buckling load of smart skin where shear deformation was considerable.