• Imaging Science in Dentistry
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• 제50권3호
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• pp.183-192
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• 2020

Purpose: This study was performed to assess the accuracy of preoperative cone-beam computed tomography (CBCT), when justified for other reasons, in locating the apical foramen and establishing the working length. Materials and Methods: Six electronic databases were searched for studies on this subject. All studies, of any type, were included if they compared measurements of working length with preoperative CBCT to measurements using an electronic apex locator (EAL) or histological reference standard. Due to the high levels of heterogeneity, an inverse-variance random-effects model was chosen, and weighted mean differences were obtained with 95% confidence intervals and P values. Results: Nine studies were included. Compared to a histological reference standard, CBCT indicated that the apical foramen was on average 0.40 mm coronal of its histological position, with a mean absolute difference of 0.48 mm. Comparisons were also performed to an EAL reference standard, but the conclusions could not be considered robust due to high levels of heterogeneity in the results. Conclusion: A low level of evidence is produced suggesting that preoperative CBCT shows the apical foramen to be on average 0.40 mm coronal to its histological position, with a mean absolute difference of 0.48 mm.

• The Journal of Asian Finance, Economics and Business
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• 제8권12호
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• pp.63-73
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• 2021

This study investigates the key determinants of exchange rate (RER) misalignment for the period 1991 to 2020. The BEER technique has been used to estimate the degree of the equilibrium exchange rate. To explore the actual exchange rate misalignment and to assess the behavior of variables that are different in different regimes of undervaluation and overvaluation, the nonlinear technique of Markov regime-switching (MSM) was applied. The mean and variance of each regime are highly significant and show that undervaluation episodes have a low mean (116.139) and more volatility (1.229) while overvaluation episodes have a high mean (126.732) with less volatility (0.871). The findings show that MSM accurately identifies exchange rate misalignment in both regimes as separate incidents of overvaluation and undervaluation. Results further depict that misalignment of the RER is affected by terms of trade, net foreign assets, interest differential, government investment, and consumption decision. Results recommend that if policymakers want to use the exchange rate as a policy tool, they must first consider the drivers of the equilibrium exchange rate. As a result, any deliberate actions to address exchange rate misalignment must focus on the underlying fundamentals that drive the exchange rate.

• 대한간호학회지
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• 제44권5호
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• pp.525-533
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• 2014

Purpose: This study was done to propose and test a predictive model that would explain and predict fall prevention behaviors in postmenopausal women. The health belief model was the theoretical basis to aid development of a nursing intervention fall prevention program. Methods: Data for 421 postmenopausal women were selected from an original data set using a survey design. The structural equation model was tested for 3 constructs: modifying factors, expectation factors, and threat factors. Expectation factors were measured as relative perceived benefit (perceived benefit minus perceived barrier), self-efficacy, and health motivation; threat factors, as perceived susceptibility (fear of falling) and perceived severity (avoiding activity for fear of falling); and modifying factors: level of education and knowledge about fall prevention. Data were analyzed using SPSS Windows and AMOS program. Results: Mean age was 55.7 years (range 45-64), and 19.7% had experienced a fall within the past year. Fall prevention behaviors were explained by expectation and threat factors indicating significant direct effects. Mediating effect of health beliefs was significant in the relationship between modifying factors and fall prevention behaviors. The proposed model explained 33% of the variance. Conclusion: Results indicate that fall prevention education should include knowledge, expectation, and threat factors based on health belief model.

• 한국농공학회논문집
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• 제60권1호
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• pp.111-120
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• 2018

The purpose of this study was to develop a ridge regression (RR) model to estimate BOD and TP load using runoff weighted value. The concept of runoff weighted value, based on distributed curve-number (CN), was introduced to reflect the impact of land covers on runoff. The estimated runoff depths by distributed CN were closer to the observed values than those by area weighted mean CN. The RR is a technique used when the data suffers from multicollinearity. The RR model was developed for five flow duration intervals with the independent variables of daily runoff discharge of seven land covers and dependent variables of daily pollutant load. The RR model was applied to Heuk river watershed, a subwatershed of the Han river watershed. The variance inflation factors of the RR model decreased to the value less than 10. The RR model showed a good performance with Nash-Sutcliffe efficiency (NSE) of 0.73 and 0.87, and Pearson correlation coefficient of 0.88 and 0.93 for BOD and TP, respectively. The results suggest that the methods used in the study can be applied to estimate pollutant load of different land cover watersheds using limited data.

• 농촌의학ㆍ지역보건
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• 제32권1호
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• pp.27-39
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• 2007

Objectives: The challenge of an increasing elderly population has coupled with everpresent social concerns in Korea. A major problem in health center for the frail older people is that medical, healthcare, and welfare services are often fragmented in terms of providers and settings without appropriate coordination. The purpose of this study was to investigate the need of health center-based integrated healthcare services and its related factors for the elderly. Methods: A total of 110 elderly people who had visited at a county Health Center were interviewed using a self-administered questionnaire from November to December, 2005. The questionnaire consists of five domains according to the Program of All-inclusive Care for the Elderly. Results: Respondents had high need (total mean score with the 5-point Likert-type sacle: 3.67) of health center-based integrated healthcare services including home visiting service (mean: 4.08), chronic disease care service (mean: 4.06), and transportation service (mean 4.05). According to the results of hierarchical multiple regression analysis, among three regression models the magnititude of the variance of full model that is explained by the need of welfare-domain service was significantly larger than two reduced model. Income was a significant variable in increasing the need of health care and welfare services. Conclusions: This study suggests that the health center-based integrated healthcare services for the elderly must be continuously developed and provided for the health promotion and improved the quality of life of the elderly who live in rural area in Korea.

• Journal of Nutrition and Health
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• 제37권3호
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• pp.210-222
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• 2004

In recent years, the number and proportion of Korean elderly have grown rapidly, and elderly individuals show a disproportionate risk for poor nutritional status. The purpose of this study was to examine the relationship of sociodemographic background to nutrient intake of persons 65 years of age or older, living in 15 cities in Korea. Data on 1973 subjects (603 males, 1370 females), who participated in the Korean Elderly Nutrition Survey (2000), were analyzed. Their mean age was 72.3 years and their mean body mass index (BMI) was 24.2 kg/$m^2$. Basic sociodemographic data were obtained through personal interviews. The 98-item semi-food frequency questionnaire, developed and previously validated for Korean middle-aged and elderly subjects, was administered. “Percentage of subjects who consumed under 75％ Korean RDA,” “number of nutrients consumed below 75％ Korean RDA,” “mean nutrient adequacy ratio,” and “nutrient density” were used to determine nutritional status. Male elderly had better nutritional quality than female elderly. Nutritional quality decreased with age, especially in older elderly (over 75). Elderly who were underweight (BMI 〈 20 kg/$m^2$) showed poorer nutritional quality than those who were normal weight (BMI 20∼25 kg/$m^2$) and overweight (BMI $\geq$ 25 kg/$m^2$). Elderly who lived alone had significantly poorer nutritional quality than those who lived with a spouse, and/or with children. Lower education level and economic dependence also showed lower nutritional quality. A stepwise multiple regression analysis was performed to examine the effects of specific sociodemographic factors on nutritional quality. For number of nutrients under 75％ RDA as a dependent variable, education level explained 4.8％ of the variance, followed by living status, age, body mass index, gender, and living expense support (Model $R^2$ = 0.091). For mean nutrient adequacy ratio as a dependent variable, model $R^2$ was 0.098. Therefore, sociodemographic variables such as gender, age, body mass index, living status, educational level, and economic status influenced elderly nutrition status. These results indicate that an elderly nutrition intervention should focus on subjects who are poorly educated, living alone, age 75 or older, and/or underweight.

• 여성건강간호학회지
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• 제29권4호
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• pp.302-316
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• 2023

Purpose: This study aimed to develop and validate a structural model for the quality of life (QoL) among high-risk pregnant women, based on Roy's adaptation model. Methods: This cross-sectional study collected data from 333 first-time mothers diagnosed with a high-risk pregnancy in two obstetrics and gynecology clinics in Cheonan, Korea, or participating in an online community, between October 20, 2021 and February 20, 2022. Structured questionnaires measured QoL, contextual stimuli (uncertainty), coping (adaptive or maladaptive), and adaptation mode (fatigue, state anxiety, antenatal depression, maternal identity, and marital adjustment). Results: The mean age of the respondents was 35.29±3.72 years, ranging from 26 to 45 years. The most common high-risk pregnancy diagnosis was gestational diabetes (26.1%). followed by preterm labor (21.6%). QoL was higher than average (18.63±3.80). Above-moderate mean scores were obtained for all domains (psychological/baby, 19.03; socioeconomic, 19.00; relational/spouse-partner, 20.99; relational/family-friends, 19.18; and health and functioning, 16.18). The final model explained 51% of variance in QoL in high-risk pregnant women, with acceptable overall model fit. Adaptation mode (β=-.81, p=.034) and maladaptive coping (β=.46 p=.043) directly affected QoL, and uncertainty (β=-. 21, p=.004), adaptive coping (β=.36 p=.026), and maladaptive coping (β=-.56 p=.023) indirectly affected QoL. Conclusion: It is essential to develop nursing interventions aimed at enhancing appropriate coping strategies to improve QoL in high-risk pregnant women. By reinforcing adaptive coping strategies and mitigating maladaptive coping, these interventions can contribute to better maternal and fetal outcomes and improve the overall well-being of high-risk pregnant women.

• 응용통계연구
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• 제35권2호
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• pp.229-250
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• 2022

포트폴리오 최적화 이론의 초석인 Markowitz의 평균-분산 포트폴리오 모형 (1952)이 발표된 이후로 많은 분야에서 포트폴리오 최적화에 대한 다양한 연구가 진행되었다. 기존의 평균-분산 포트폴리오 모형은 주로 목적함수나 제약식에 비선형 볼록 형태를 포함한다. 이를 Dantzig의 선형계획법을 적용하여 선형으로 변환시켜 알고리즘 계산 시간을 효율적으로 감소시켰다. 또한 시계열 데이터 특성을 반영하여 시간에 따른 가중치를 고려하는 가우시안 커널 가중치 공분산을 제안하였다. 여기에 일정 부분은 벤치마크에 투자하고 나머지는 포트폴리오 최적화 모형으로 제안된 자산들에 투자하는 퍼터베이션 방법을 적용하여 평균 수익률과 위험도를 목적에 맞게 조절하도록 하였다. 또한, 본 논문에서는 안정적이면서도 적은 자산을 보유하게 포트폴리오를 구성하여 관리비용(management costs)과 거래비용(transaction costs)를 낮출 수 있는 Dantzig-type 퍼터베이션 포트폴리오 모형을 제안하였다. 제안된 모형의 성능은 5개의 실제 데이터 세트로 벤치마크 포트폴리오와 비교 분석하여 평가하였다. 최종적으로 제안한 최적화 모형은 벤치마크보다 높은 기대수익률이나 낮은 위험도를 갖는 포트폴리오를 구성하여 퍼터베이션 목적을 만족하며, 투자한 자산의 수와 시간에 따른 자산 구성 변화를 일정 수준 이하로 조절하는 희소하며 안정적인 결과를 얻었다.

• 응용통계연구
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• 제6권1호
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• pp.145-162
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• 1993

본 논문에서는 반복적 계속 표본조사에서 일부의 표본을 교체하는 2회 계속조사의 표본 추 출법들을 요약하고 앞 조사시기의 관찰값을 확률측도로 이용한 RHC(Rao-Hartley-Cochran) 유형의 불균등 확률추출법을 제안하였다. 제안된 추출법과 기존의 확률추출법의 비교를 위 하여 둘째 조사시기의 모평균 추정량과 그의 분산을 유도하였으며, 제안된 추출법의 상대 효율은 이론적인 측면과 수치적 시뮬레이션 방법으로 비교 분석되었다. 시뮬레이션 비교를 위하여 한 특별한 시계열 모형을 가정하고 이를 사용하여 인위적인 모집단을 생성하였으며 이 모집단에서 각 추출법에 해당되는 표본을 컴퓨터로 추출하여 각각의 추정치를 계산하여 비교한 결과에서 RHC 유형의 새로 제안된 추출법의 분산과 편차가 일반적으로 적음을 보 였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1493-1510
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• 2000

Theoretical models that can be used to predict the range of main lobe widths and the probability distribution of the peak sidelobe levels of two-dimensionally sparse arrays are presented here. The arrays are considered to comprise microphones that are randomly positioned on a segmented grid of a given size. First, approximate expressions for the expected squared magnitude of the aperture smoothing function and the variance of the squared magnitude of the aperture smoothing function about this mean are formulated for the random arrays considered in the present study. By using the variance function, the mean value and the lower end of the range i.e., the first I percent of the mainlobe distribution can be predicted with reasonable accuracy. To predict the probability distribution of the peak sidelobe levels, distributions of levels are modeled by a Weibull distribution at each peak in the sidelobe region of the expected squared magnitude of the aperture smoothing function. The two parameters of the Weibull distribution are estimated from the means and variances of the levels at the corresponding locations. Next, the probability distribution of the peak sidelobe levels are assumed to be determined by a procedure in which the peak sidelobe level is determined as the maximum among a finite number of independent random sidelobe levels. It is found that the model obtained from the above approach predicts the probability density function of the peak sidelobe level distribution reasonably well for the various combinations of two different numbers of microphones and grid sizes tested in the present study. The application of these models to the design of random, sparse arrays having specified performance levels is also discussed.