• 제목/요약/키워드: mean-variance model

검색결과 473건 처리시간 0.025초

해양모니터링 자료의 장기결측 보충 기법 (Long-gap Filling Method for the Coastal Monitoring Data)

  • 조홍연;이기섭;이욱재
    • 한국해안·해양공학회논문집
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    • 제33권6호
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    • pp.333-344
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    • 2021
  • 해양모니터링 자료에서 빈번하게 발생하는 장기결측구간의 자료 보충기법을 제안한다. 제안하는 방법은 결측구간의 장기변동 추세 성분과 단기변동 잔차성분을 추정하여 조합하는 방식으로 결측구간의 미지 정보를 추정한다. 이 방법을 이용하여 울릉도 해상부이 자료의 수온 항목, 약 1개월 정도의 장기결측 구간의 자료를 보충하였으며, 부이에서 관측하는 자료 항목에 대해서도 결측 보충을 수행하였다. 보충된 자료는 항목에 따라 차이를 보이지만 변동양상이 적절하게 재현되는 것으로 파악되었다. 이 방법은 추세추정과 잔차 반영에 따른 편향오차와 분산오차가 발생하지만, 장기결측으로 인한 통계적인 측도 추정의 편향오차는 크게 절감하는 것으로 파악되었다. 결측보충 모형의 추정 RMS 오차의 평균과 90% 신뢰구간은 각각 0.93, 0.35~1.95 범위이다.

Laser-assisted Delivery of a Combined Antioxidant Formulation Enhances the Clinical Efficacy of Fractional Microneedle Radiofrequency Treatment: A Pilot Study

  • Kim, Jihee;Kim, Soo Min;Jung, Bok Ki;Oh, Sang Ho;Kim, Young-Koo;Lee, Ju Hee
    • Medical Lasers
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    • 제10권3호
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    • pp.161-169
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    • 2021
  • Background and Objectives Fractional microneedle radiofrequency systems are popular options to increase elasticity in aging skin. Laser-assisted drug delivery is a promising method for the epidermal injection of topically applied drugs and cosmetic ingredients. This study assesses the safety and efficacy of topical delivery of L-ascorbic acid, vitamin E, and ferulic acid after fractional microneedle radiofrequency treatment for reducing photodamage. Materials and Methods In this prospective, single-center, split-face, controlled pilot study, six women (mean age, 48.0 years; range, 35-57 years; Fitzpatrick skin types III and IV) exhibiting mild to moderate photodamage, underwent a single session of fractional microneedle radiofrequency treatment. The patients were instructed to apply the antioxidant formulation to only one side of the face. Patients were evaluated 3 days, 7 days, and 4 weeks thereafter, using three-dimensional imaging and ultrasound. Ex vivo, the full-thickness human skin was used for molecular and histological evaluation. Statistical analysis was achieved by applying t-tests, Mann-Whitney U tests, and one-way analyses of variance. Results Compared to the untreated side, the antioxidant-treated side exhibited a significant increase in dermal thickness (10.32% vs. 17.54%, p < 0.05), but not in skin elasticity (4.76% vs. 4.69%, p > 0.05). The difference in erythema between the sides was statistically not significant (p > 0.05). In the ex vivo model, expression of FGF2 in the skin was significantly increased after application of the antioxidant formulation, as compared to results obtained subsequent to fractional microneedle radiofrequency treatment only (p < 0.01). Conclusion This study demonstrates that for the treatment of photodamaged skin, laser-assisted delivery of the antioxidant formulation is a safe and effective adjuvant modality following fractional microneedle radiofrequency.

간호대학생의 완벽주의 성향과 임상실습현장지도자의 돌봄에 대한 지각이 임상실습 중 경험한 무례함에 미치는 영향 (The influence of nursing students' perfectionism tendency and perception of instructor caring on incivility experienced by nursing students)

  • 이은남;김나경
    • 한국간호교육학회지
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    • 제27권4호
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    • pp.436-446
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    • 2021
  • Purpose: The purpose of this study was to identify the influences of nursing students perfectionism tendencies and their perception of instructor caring on incivility experienced by nursing students during clinical practice. Methods: A descriptive correlational study was conducted. The participants were 244 nursing students from five universities in B city. Data were analyzed using an independent t-test, ANOVA, Pearson's correlation coefficient, Scheffé test and a stepwise regression analysis. Results: The mean score for incivility in nursing students was 2.61 out of 5 points. The explanatory power of the model for incivility was in nursing students 52.8% of the variance in training in student's university hospital (𝛽=-.15, p=.002), total period of clinical practice (𝛽=.17, p<.001), confidence through caring (𝛽=-.23, p<.001), respectful sharing (𝛽=-.15, p=.005), supportive learning climate (𝛽=-.15, p=.005), self-oriented perfectionism (𝛽=.14, p=.004), and socially prescribed perfectionism (𝛽=.18, p<.001). Conclusion: The research results suggest that instructor caring is an important factor in regard to the incivility of nursing students. Organizational efforts and institutional devices will be needed to improve the incivility in clinical environments. By communicating with students and showing them respect, clinical nurses will help nursing students cope with incivility and recognize the clinical practice education environment positively.

Validation and comparison of volume measurements using 1 multidetector computed tomography and 5 cone-beam computed tomography protocols: An in vitro study

  • Juliana Andrea Correa, Travessas;Alessandra Mendonca, dos Santos;Rodrigo Pagliarini, Buligon;Nadia Assein, Arus;Priscila Fernanda Tiecher, da Silveira;Heraldo Luis Dias, da Silveira;Mariana Boessio, Vizzotto
    • Imaging Science in Dentistry
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    • 제52권4호
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    • pp.399-408
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    • 2022
  • Purpose: The purpose of this study was to compare volume measurements obtained using 2 image software packages on Digital Imaging and Communications in Medicine (DICOM) images acquired from 1 multidetector computed tomography and 5 cone-beam computed tomography devices, using different protocols for physical volume measurements. Materials and Methods: Four pieces of bovine leg were prepared. Marrow was removed from 3 pieces, leaving cortical bone exposed. The resulting space of 1 piece was filled with water, another was filled with propylene glycol, and the third was left unfilled. The marrow in the fourth sample was left fully intact. Volume measurements were obtained after importing DICOM images into the Dolphin Imaging 11.95 and ITK-SNAP software programs. Data were analyzed using 3-way analysis of variance with a generalized linear model to determine the effects of voxel size, software, and content on percentage mean volume differences between tomographic protocols. A significance level of 0.05 was used. Results: The intraclass correlation coefficients for intraobserver and interobserver reliability were, respectively, 0.915 and 0.764 for the Dolphin software and 0.894 and 0.766 for the ITK-SNAP software. Three sources of statistically significant variation were identified: the interaction between software and content (P=0.001), the main effect of content (P=0.014), and the main effect of software (P=0.001). Voxel size was not associated with statistically significant differences in volume measurements. Conclusion: Both content and software influenced the accuracy of volume measurements, especially when the content had gray values similar to those of the adjacent tissues.

방사선사의 초음파검사 시 체감하는 직무만족도의 구조적 관계 해석 (Analysis of Structural Relationship of Job Satisfaction Levels Felt in Ultrasound Examination by Radiological Technologists)

  • 김혜진;성열훈
    • 대한방사선기술학회지:방사선기술과학
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    • 제46권4호
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    • pp.325-336
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    • 2023
  • The purpose of this study was to analyze the structural relationship between job satisfaction levels felt during ultrasound examination of radiological technologists (RTs) using a structural equation model. The subjects were a total of 203 RTs currently working in medical institutions. The method was conducted as a survey study using a questionnaire consisting of a total of 29 questions consisting of demographic characteristics and job satisfaction levels that were self-efficacy, job competency, extrinsic compensation, and job satisfaction. The reliability was secured with the Cronbach's alpha coefficient of 0.6 or higher. For statistical analysis, a significant difference between the frequency analysis of demographic characteristics and the mean of the job satisfaction levels were performed by independent sample T-test and one-way analysis of variance (ANOVA) followed by Scheffe's post hoc test. The correlation analysis between variables was tested with Spearman's and Pearson's correlation coefficient. We analyzed the structural relationships between variables by structural equations. As a result, first, job competency and extrinsic compensation had a positive effect on job satisfaction on ultrasound examination of RTs. Second, the self-efficacy of ultrasound examination RTs showed a high correlation with job competency. Third, the job satisfaction levels showed in the order of job competency, job satisfaction, self-efficacy, and extrinsic compensation. In conclusion, this study are expected to be provided as data to identify factors that could improve job satisfaction during ultrasound examination of RTs by empirically analyzing the structural relationship of self-efficacy, job competency, and external compensation.

The impact of peripheral neuropathy symptoms, self-care ability, and disturbances to daily life on quality of life among gynecological cancer patients undergoing chemotherapy: a cross-sectional survey

  • Sohee Mun;Hyojung Park
    • 여성건강간호학회지
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    • 제28권4호
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    • pp.296-306
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    • 2022
  • Purpose: This study investigated the effects of peripheral neuropathy symptoms, self-care ability, and disturbances to daily life on quality of life (QoL) among gynecological cancer patients undergoing chemotherapy. Methods: The participants included 144 patients with gynecological cancer undergoing anticancer chemotherapy at a tertiary hospital in Seoul, South Korea, from December 1, 2021 to January 28, 2022. Convenience sampling was used to recruit patients who had received 4 or more cycles of chemotherapy using a paclitaxel-platinum regimen, and a self-reported questionnaire was used to collect data. Descriptive statistics, the t-test, analysis of variance, Scheffé test, Pearson correlation coefficients, and multiple regression analysis were performed. Results: Most of the participants had ovarian cancer (70.1%) or endometrial cancer (14.6%), and the most common number of treatment cycles was 6 to 10 (29.2%). The mean QoL (60.83±19.89) was greater than the midpoint. The regression model analyzing the patients' QoL was statistically significant (F=15.38, p<.001) with an explanatory power of 56.7%. Self-care ability (β=.39, p<.001), disturbances to daily life (β=-.38, p<.001), the duration of peripheral neuropathy symptoms (β=2.14, p=.034), and regular exercise (β=-2.12, p=.036) were found to significantly affect QoL. Conclusion: Efforts to improve the self-care ability of gynecological cancer patients who have experienced peripheral neuropathy after receiving chemotherapy and mitigate disturbances to their daily life can improve their QoL. Healthcare professionals should identify peripheral neuropathy symptoms and examine the effects of the symptoms on patients' daily lives. Improving the self-care ability of patients and alleviating their limitations in daily life may improve QoL.

우울장애에서 지각된 스트레스 정도가 희망감에 미치는 영향 : 인지적 정서조절 전략 차이 (Effects of Perceived Stress on State Hope in Patients with Depression : Differences of Cognitive Emotional Regulation)

  • 이나빈;민정아;채정호
    • 우울조울병
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    • 제9권2호
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    • pp.78-86
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    • 2011
  • Objectives : The aim of this study was to investigate relationship between perceived stress level, cognitive emotion regulation (CER) strategy and hope in group with high depressive symptom and higher-level perceived stress (H-H) and group with high depressive symptom and lower-level perceived stress (H-L) in patients with depression. Method : A total of 85 patients (over score of 16 by Beck depression Inventory; BDI) were surveyed with Cognitive emotion regulation questionnaire (CERQ), Perceived stress scale (PSS), and The state hope scale (SHS). Mean scores of CERQ and SHS were compared between relatively higher perceived stress and lower perceived stress groups. Correlation analysis and multiple linear regression analyses were performed to identify the effect of BDI, PSS and CER strategy on SHS in two groups. Results : In ANOVA, the level of hope and maladaptive CERQ score proved to be significantly lower among the H-H group than among the H-L group, while adaptive CERQ scores were not. In Regression analysis, the effective CER strategy in SHS were 'Refocus on planning' in H-H group, while it was 'Acceptance' CER strategy in H-L group. The final regression model explained 36% of the variance of SHS in H-H group and explained 21% of SHS in H-L group. Conclusion : These findings suggest that 'Refocus on planning' and 'Acceptance' cognitive emotion strategy are helpful in promotion of state hope on depression. Especially, 'Refocus on planning' strategy is more effective in high depressive symptom and high-perceived stress level, while 'Acceptance' strategy help to promote hope in high depressive symptom and low-perceived stress level in patients with depression.

임상간호사의 그릿, 사회적 지지, 잡 크래프팅, 근거기반 실무역량이 직무만족도에 미치는 영향 (Effects of Clinical Nurses' Grit, Social Support, Job Crafting, and Evidence-Based Practice Competency on Job Satisfaction)

  • 서보람;강경림;박교연
    • 임상간호연구
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    • 제30권1호
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    • pp.54-64
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    • 2024
  • Purpose: This descriptive survey study aimed to examine the effects of grit, social support, job crafting, and evidence-based practice competency on job satisfaction among nurses. Methods: The participants of this study were 211 clinical nurses with experience of more than six months. Data were collected using through an online survey from February 1 to February 17, 2023. The questionnaires was consisted of general characteristics, grit, social support, job crafting, evidence-based practice competency, and job satisfaction. Data were analyzed using descriptive statistics(frequency, percentage, mean, and standard deviation), t-test, ANOVA, Pearson correlation coefficient, and multiple regression analysis with the SPSS/WIN 28.0 program. Results: The average scores of the main variables were 3.08±0.44 out of four for grits, 3.67±0.52 out of five for social support, 4.20±0.64 out of five for job crafting, 4.84±0.71 out of seven for evidence-based practice competency, and 3.72±0.55 out of five for job satisfaction. In the regression model, the factors affecting the nurses' job satisfaction were grit (β=0.66, p<.001) and social support (β=0.11, p=.046), which explained 78.7% of the variance in job satisfaction. Job crafting and evidence-based practice competency were correlated with job satisfaction; however, there was no statistically significant effects of these variables on job satisfaction. Conclusion: Based on the findings of this study, grit and social support showed the most significant effects on the job satisfaction of nurses. Therefore, active support is needed to develop a strategy to improve nurses' grit and to create a supportive work environment, which would be helpful to increase their job satisfaction.

데이터기반의 신규 사업 매출추정방법 연구: 지능형 사업평가 시스템을 중심으로 (A Data-based Sales Forecasting Support System for New Businesses)

  • 전승표;성태응;최산
    • 지능정보연구
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    • 제23권1호
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    • pp.1-22
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    • 2017
  • 사업타당성 분석이나 기업 기술가치평가 등 미래의 사업에 대한 진입이나 투자 타당성을 분석하기 위해서는 새로운 사업과 관련한 시장을 추정하고 그 안에서 확보 가능한 매출을 객관적으로 추정하는 과정이 필수 불가결하다. 이런 신규 매출이나 시장규모의 추정 방법은 다양한 방법으로 구분이 가능한데 크게 정량적인 방법과 정성적인 방법으로 구분할 수 있다. 그러나 두 가지 방법 모두 많은 자원과 시간을 필요로 한다. 그래서 우리는 신규 사업의 평가지원을 위한 데이터 기반의 지능형 매출 예측 시스템을 제안하고자 한다. 본 연구는 사업타당성 분석이나 기술가치평가를 위한 신규 사업의 매출 추정 시스템을 개발하는데, 알고리즘 기반으로 전통적인 정량 예측방법 중 하나인 유추방법에 주목했다. 동일한 국내 산업에서 최근 창업한 기업의 매출 실적을 국내 신규 사업의 매출액을 추정하는 유추 대상 변수로 활용할 수 있는지 검토한다. 여기서 유추예측 대상은 최초 매출액과 초기 성장률이며, 주요 비교 차원은 산업분류, 창업시기 등이 고려된다. 특히 본 연구는 우리나라 창업 기업이 가지는 매출 성장률의 평균회귀 현상을 활용하는 지능형 정보 지원 시스템을 제안하다. 본 연구에서는 신규 매출 추정을 위해서 역사적 자료인 창업 매출 실적을 활용하는 방법이 적절한지 판단하기 위해서 잠재성장모형 등을 활용해 산업분류에 따른 신규 사업의 초기 매출액과 연도별 성장률이 산업분류별로 차이가 있는지 분석한다. 기존 기업의 창업 후 4년간 매출 성과의 종단자료를 잠재성장모형으로 분석하는데, 특정 산업분류에서 차이를 보여주는지 분석해 산업분류가 유추 예측에서 고려해야할 유의미한 변수인지 분석하는 것이다. 본 연구의 결과는 신속하고 객관적인 신규 사업 매출 추정을 가능하게 하는 지능형 정보시스템을 개발하게 해서 사업성타당성 분석이나 기술가치평가 과정의 효율성을 개선시켜 줄 것으로 기대된다.

제주지역 감귤가격의 시계열적 특성 및 가격변동성에 관한 연구 (A Study on Price Volatility and Properties of Time-series for the Tangerine Price in Jeju)

  • 고봉현
    • 한국산학기술학회논문지
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    • 제21권6호
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    • pp.212-217
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    • 2020
  • 본 연구의 목적은 Bollerslev(1986)의 GARCH 모형을 이용하여 제주지역 감귤가격의 시계열적 특성과 가격변동성(price volatility)에 대한 실증분석을 수행하는 것이다. 본 연구의 주요결과는 다음과 같이 요약된다. 첫째, 감귤 가격 변화율의 시계열이 정규분포가 아닌 꼬리가 두터운 분포를 지니고 있는 것으로 나타났다. 이는 Jarque-Bera 통계량이 1%의 유의수준에서 감귤 가격변화율의 시계열의 분포가 정규분포라는 귀무가설을 기각함으로써 검증되었다. 둘째, Ljung-Box Q 통계량을 통해 감귤 가격변화율 시계열 간 상관관계가 높은 것으로 분석되었으며, 이는 ARCH-LM 검정을 통해 통계적으로 검증되었다. 셋째 GARCH(1,1) 모형 추정결과, 평균방정식의 상수항을 제외하고는 모든 계수의 추정 값이 1%의 유의수준에서 통계적으로 유의한 결과를 보였다. 그리고 분산방정식의 지속성 모수(λ=α11) 값이 1에 근접한 것으로 추정되었다. 이는 현재와 유사한 변동성 수준이 장래에도 지속될 가능성이 매우 높은 것으로 해석된다. 그리고 이러한 결과는 제주감귤 가격변화율 시계열에서도 기존의 선행연구에서처럼 '변동성 군집(volatility clustering)' 현상이 나타나고 있음을 밝혀낸 것이다. 끝으로, 본 연구의 결과는 정부의 감귤 수급조절정책을 수립하는데 유용한 기초 자료로 활용될 수 있을 것으로 기대된다.