• Journal of Preventive Medicine and Public Health
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• 제53권6호
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• pp.465-475
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• 2020

Objectives: This study was conducted to examine the association between birth patterns (defined in terms of birth order and interval) with delayed breastfeeding initiation in Indonesia. Methods: A cross-sectional study was carried out using data from the Indonesian Demographic and Health Survey 2017. The weighted number of respondents was 5693 women aged 15-49 years whose youngest living child was less than 2 years old. Multivariable logistic regression was conducted to evaluate associations between birth patterns and delayed breastfeeding initiation after adjusting for other covariates. Results: This study found that 40.2% of newborns in Indonesia did not receive timely breastfeeding initiation. Birth patterns were significantly associated with delayed breastfeeding initiation. Firstborn children had 77% higher odds of experiencing delayed breastfeeding initiation (adjusted odds ratio, 1.77; 95% confidence interval, 1.02 to 3.04; p<0.05) than children with a birth order of 4 or higher and a birth interval ≤ 2 years after adjusting for other variables. Conclusions: Firstborn children had higher odds of experiencing delayed breastfeeding initiation. Steps to provide a robust support system for mothers, especially first-time mothers, such as sufficient access to breastfeeding information, support from family and healthcare providers, and national policy enforcement, will be effective strategies to ensure better practices regarding breastfeeding initiation.

• International Journal of Quality Innovation
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• 제6권1호
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• pp.109-118
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• 2005

The parameter design is the most emphasized measure by researchers for a new products development. It is critical for makers to achieve simultaneously in both the time-to-market production and the quality enhancement. However, there are difficulties in practical application, such as (1) complexity and nonlinear relationships co-existed among the system's inputs, outputs and control parameters, (2) interactions occurred among parameters, (3) where the adjustment factors of Taguchi's two-phase optimization procedure cannot be sure to exist in practice, and (4) for some reasons, the data became lost or were never available. For these incomplete data, the Taguchi methods cannot treat them well. Neural networks have a learning capability of fault tolerance and model free characteristics. These characteristics support the neural networks as a competitive tool in processing multivariable input-output implementation. The successful fields include diagnostics, robotics, scheduling, decision-making, prediction, etc. This research is a case study of spherical annealing model. In the beginning, an original model is used to pre-fix a model of parameter design. Then neural networks are introduced to achieve another model. Study results showed both of them could perform the highest spherical level of quality.

• 제어로봇시스템학회논문지
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• 제2권1호
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• pp.9-13
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• 1996

슬라이딩 모드 제어기의 실현시 발생하는 고주파 chattering 현상을 제거하기 위하여 본 논문에서는 스위칭 표면 행렬의 Range-space 동특성을 이용한 연속 시간 스위칭 다이나믹을 제안한다. 전체 폐루프 시스템은 정칙 변환에 의해 빠른 부시스템과 느린 부시스템으로 분해되어, 결국 전체 폐루프 시스템의 고유치는 각각 스위칭 표면 행렬의 Range-space와 Null-space의 동특성을 지배하는 부시스템들의 고유치들로 구성됨을 보인다. 그리고, 정합된 불확실성이 존재하는 경우 제안된 스위칭 다이나믹을 가진 제어 시스템의 응답은 일정 시간이 경과된 후 스위칭 평면의 임의의 영역으로 균일하게 유계된다는 것을 증명한다. 또한, 제어 입력의 크기에 대한 제약성을 만족하면서도 전체 제어 시스템의 정상 상태 오차를 감소시키기 위하여 두개의 스위칭 다이나믹을 도입한 수정된 슬라이딩 모드제어기를 제안한다.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2634-2638
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• 2009

슬라이딩 모드를 가진 가변 구조 제어(VSC)에서의 불연속적인 제어 법칙은 실제로 바람직하지 못한 떨림 현상을 발생시킨다. 본 논문에서는 이러한 문제점을 해결하기 위해 신경망 슬라이딩 곡면을 갖는 VSC 구조를 제안한다. 불연속 제어 법칙을 해결하기 위해 경계층을 가진 신경망 슬라이딩 곡면이 도입된다. 제안된 제어기는 보편적인 VSC의 떨림 현상 문제를 해결할 수 있다. 제안된 제어 구조의 효과는 시뮬레이션을 통해 증명하였다.

• Journal of Power Electronics
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• 제11권5호
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• pp.743-750
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• 2011

This article deals with the sensor-less control of a DC Motor via a SEPIC Converter-Full Bridge combination powered through solar panels. We simultaneously regulate, both, the output voltage of the SEPIC-converter to a value larger than the solar panel output voltage, and the shaft angular velocity, in any of the turning senses, so that it tracks a pre-specified constant reference. The main result of our proposed control scheme is an efficient linear controller obtained via Lyapunov. This controller is based on measurements of the converter currents and voltages, and the DC motor armature current. The control law is derived using an exact stabilization error dynamics model, from which a static linear passive feedback control law is derived. All values of the constant references are parameterized in terms of the equilibrium point of the multivariable system: the SEPIC converter desired output voltage, the solar panel output voltage at its Maximun Power Point (MPP), and the DC motor desired constant angular velocity. The switched control realization of the designed average continuous feedback control law is accomplished by means of a, discrete-valued, Pulse Width Modulation (PWM). Experimental results are presented demonstrating the viability of our proposal.

• Childhood Kidney Diseases
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• 제27권2호
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• pp.111-116
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• 2023

Purpose: This article was to investigate the association between urinary tract infections (UTIs) and high weight status in infancy. Methods: We conducted a nationwide matched cohort study from January 2018 to December 2020 using data from the Korean National Health Insurance System and the Korean National Health Screening Program for Infants and Children. We analyzed the association between UTI diagnosis codes and high weight status (which was defined as being in the 90th percentile or higher of weight-for-age). Results: We found that 22.8% of infants with UTIs exhibited high weight status, compared to 20.0% of non-UTI infants (P<0.001). Per our multivariable analyses, the adjusted odds ratio for high weight status was 1.09 (95% confidence interval, 1.06-1.13). Conclusions: UTI in the first 12 months of life was associated with a weight-for-age percentile of ≥90. Our findings corroborate those of previous single-center studies and emphasize the importance of careful monitoring for this at-risk group.

• 보건행정학회지
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• 제28권2호
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• pp.178-185
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• 2018

Background: We investigated association between introduction of the diagnosis-related groups (DRG) system for anal operation and length of stay. Also, we investigated how it is different among hospitals with longer length of stay and among hospitals with shorter length of stay before introduction of the DRG system. Methods: We used data from Health Insurance Review and Assessment which were national health insurance claim data. Total 13,111 cases of anal surgery cases were included which were claimed by hospitals since July 2012 to June 2014. Two-level multivariable regression was conducted to analysis the association between length of stay and characteristics of hospital and patient. Results: Before introducing DRGs, the average length of stay was 5.41 days. After introducing DRGs, average length of stay was decreased to 3.92 days. After introducing DRGs, length of stay has decreased (${\beta}=-1.0450$, p<0.0001) and it was statistically significant. Among hospitals which had short length of stay (shorter than mean of length of stay) before introducing DRGs, effect of introducing DRGs was smaller (${\beta}=-0.4282$, p<0.0001). On contrary, among hospitals which had long length of stay (longer than mean of length of stay) before introducing DRGs, effect of introducing DRGs was bigger (${\beta}=-1.8280$, p<0.0001). Conclusion: Introducing DRGs was more effective to hospitals which had long length of stay before introducing DRGs.

• 지역사회간호학회지
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• 제31권4호
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• pp.436-446
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• 2020

Purpose: This study aims to explore the association between unemployment and depression in people from different age groups ranging from 18 to 65 years old. Methods: This study used a cross-sectional design. We performed bivariate analysis and multivariable logistic regression on the 2010 Behavioral Risk Factor Surveillance System (BRFSS) data from 12 states in the United States. Results: On a sample comprised of n=53,406 individuals, of whom 2,546 (7.8%) were identified as being depressed and 3,448 (10.6%) as unemployed, we found that individuals aged 61~65 years have a lower depression risk compared to those aged 18-25 after adjusting for other variables including employment status. However, people from 61~65 have higher increased risk of depression when unemployed compared to other age groups in all three models tested (3.95 times higher in unemployed people in model 1, and 2.81 times higher in model 2 and model 3). Conclusion: Our findings indicate that there may need to be more focus on older adults who are unemployed, with associated support services for their mental health. The results of our study indicate that although older adults are less likely to be unemployed, there are more likely to experience depression if they are unemployed (once other confounding factors are taken into account) than younger adults. Policies and interventions can be developed to address not only the physical difficulties but also the mental challenges with which older adults can be at risk facing in case of unemployment.

• 한국산업보건학회지
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• 제32권3호
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• pp.253-267
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• 2022

Objectives: This study was performed to check whether the CRS (Chemical Ranking and Scoring) system is appropriate as a method to determine substances as candidates for substances subject to permission and to apply this system to the selection of candidates for substances subject to permission. Methods: A risk score was obtained by multiplying the hazard score and the exposure score and then ranking them. The hazard sub-indicators are carcinogenicity, germ cell mutagenicity, reproductive toxicity, specific target organ toxicity-repeated exposure, respiratory sensitization and endocrine disrupting chemicals. Exposure sub-indicators are persistence, bioaccumulation and emission volume. Sensitivity analysis was performed for missing values. Correlation analysis and multivariable linear regression analysis were performed among hazard, exposure and risk in order to confirm that CRS was an appropriate method. Results: As a result of the sensitivity analysis on missing values, it was confirmed that the effect on the risk ranking was not sensitive. Correlation and regression analysis confirmed that exposure had a greater effect on risk than hazard. Conclusions: The CRS system, which derives a risk score using a hazard and exposure score, is judged to be appropriate as a method for the selection of preliminary of candidates for substances subject to permission. Benzene, cadmium, nickel, and cobalt were selected as priority candidates for substances subject to permission.

• Korean Circulation Journal
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• 제53권9호
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• pp.606-618
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• 2023

Background and Objectives: The prognostic or safety implication of renin-angiotensin-aldosterone system inhibitors (RASi) in hypertrophic cardiomyopathy (HCM) are not well established, mainly due to concerns regarding left ventricular outflow tract (LVOT) obstruction aggravation. We investigated the implications of RASi in a sizable number of HCM patients. Methods: We enrolled 2,104 consecutive patients diagnosed with HCM in 2 tertiary university hospitals and followed up for five years. RASi use was defined as the administration of RASi after diagnostic confirmation of HCM. The primary and secondary outcomes were all-cause mortality and hospitalization for heart failure (HHF). Results: RASi were prescribed to 762 patients (36.2%). During a median follow-up of 48.1 months, 112 patients (5.3%) died, and 94 patients (4.5%) experienced HHF. Patients using RASi had less favorable baseline characteristics than those not using RASi, such as older age, more frequent history of comorbidities, and lower ejection fraction. Nonetheless, there was no difference in clinical outcomes between patients with and without RASi use (log-rank p=0.368 for all-cause mortality and log-rank p=0.443 for HHF). In multivariable analysis, patients taking RASi showed a comparable risk of all-cause mortality (hazard ratio [HR], 0.70, 95% confidence interval [CI], 0.43-1.14, p=0.150) and HHF (HR, 1.03, 95% CI, 0.63-1.70, p=0.900). In the subgroup analysis, there was no significant interaction of RASi use between subgroups stratified by LVOT obstruction, left ventricular (LV) ejection fraction, or maximal LV wall thickness. Conclusions: RASi use was not associated with worse clinical outcomes. It might be safely administered in patients with HCM if clinically indicated.