• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.12
• /
• pp.1759-1771
• /
• 2017

In this paper, an improved continuous integral variable structure systems(ICIVSS) with the prescribed control performance is designed for simple regulation controls of uncertain general linear systems. An integral sliding surface with an integral state having a special initial condition is adopted for removing the reaching phase and predetermining the ideal sliding trajectory from a given initial state to the origin in the state space. The ideal sliding dynamics of the integral sliding surface is analytically obtained and the solution of the ideal sliding dynamics can predetermine the ideal sliding trajectory(integral sliding surface) from the given initial state to the origin. Provided that the value of the integral sliding surface is bounded by certain value by means of the continuous input, the norm of the state error to the ideal sliding trajectory is analyzed and obtained in Theorem 1. A corresponding discontinuous control input with the exponential stability is proposed to generate the perfect sliding mode on the every point of the pre-selected sliding surface. For practical applications, the discontinuity of the VSS control input is approximated to be continuous based on the proposed modified fixed boundary layer method. The bounded stability by the continuous input is investigated in Theorem 3. With combining the results of Theorem 1 and Theorem 3, as the prescribed control performance, the pre specification on the error to the ideal sliding trajectory is possible by means of the boundary layer continuous input with the integral sliding surface. The suggested algorithm with the continuous input can provide the effective method to increase the control accuracy within the boundary layer by means of the increase of the $G_1$ gain. Through an illustrative design example and simulation study, the usefulness of the main results is verified.

• Journal of the Korean Chemical Society
• /
• v.51 no.3
• /
• pp.279-286
• /
• 2007

In this study, we investigated the influences of cognitive conflict and situational interest induced by a discrepant event and an alternative hypothesis, attention and state learning strategies on conceptual change. A preconception test was administered to 486 seventh graders. They also completed the questionnaires of cognitive response and situational interest to a discrepant event before/after presenting an alternative hypothesis. After learning the concept of density with a CAI program as conceptual change intervention, the tests of attention, state learning strategies, and conceptual understanding were administered as posttests. Analyses of the results for 197 students having misconceptions about density revealed that post-cognitive conflict was significantly higher than pre-cognitive conflict. However, there was no statistically significant difference between the test scores of pre-situational interest and post-situational interest. Pre-cognitive conflict only exerted a direct effect on post-cognitive conflict, while post-cognitive conflict exerted a direct effect and Journal of the Korean Chemical Society an indirect effect via attention on conceptual understanding. Both pre- and post-situational interests were found to influence on conceptual understanding via attention. Attention had influences positively on deep learning strategy and negatively on surface learning strategy. There was a relatively small effect of state learning strategies on conceptual understanding.

• Korean Journal of Social Welfare Studies
• /
• v.42 no.4
• /
• pp.263-293
• /
• 2011

There have been many studies on the relationship between welfare states and the poverty. Yet, only a few studies have been addressed the poverty alleviation effect of public pension using difference in difference(DID). This study aims to analyze poverty alleviation effect for the old aged of public pension in 10 OECD countries using DID considering welfare states regimes. The empirical analyses are based on panel data of individuals aged 50 and over from two sources: SHARE in Europe(wave I~II) and HRS in USA(2004~2006). As a result of simple DID, this study provides evidence that the poverty rate of the old aged who has not been received the pension is increased, while the poverty rate of pensioner is sharply decreased. The anti-poverty effect of public pension using DID is 45.6% which is bigger than that of pre/post approach. The policy impact used by pre/post approach in conservative welfare regime is underestimated while those in liberal and socialist regime are overestimated. In last, GDP growth rate has not significant while public pension contributes to poverty alleviation effects of the old aged. Poverty alleviation effects of public pension are also varied with welfare state regimes. The poverty alleviation effects of public pension in conservative welfare and social democratic welfare state regime are significantly bigger than that in liberal welfare state regime.

• Journal of Acupuncture Research
• /
• v.26 no.2
• /
• pp.79-89
• /
• 2009

Objectives : The aim of this study was to observe the effect of acupuncture and high frequency electroacupuncture at $ST_{39}$ on intestinal motility in rats. Methods: We made over-activated state of intestinal motility with carbachol and suppressed state of intestinal motility with loperamide in rat and carried out needle retention acupuncture and high frequency electroacupuncture at $ST_{39}$ or sham point in rat divided into pre-treatment group and post-treatment group. We fed charcoal to them after the treatment and measured the travel rate of charcoal in the gastrointestinal tract to observe intestinal motility. Results : Examining intestinal motility of normal rat treated with needle retention acupuncture at $ST_{39}$ significantly suppressed intestinal motility. Pre-treatment of needle retention acupuncture significantly suppressed intestinal motility in rat which over-activated with carbachol. Pre-treatment and post-treatment of high frequency electroacupuncture significantly suppressed intestinal motility in rat which over-activated with carbachol. All of the pre-treatment and post-treatment of needle retention acupuncture, high frequency electroacupuncture showed no significant effect than control group on intestinal motility of rat which was suppressed with loperamide. Conclusions : These results suggest that acupuncture and high frequency electroacupuncture at $ST_{39}$ have preventive and therapeutic effects on over-activated intestinal motility, and high frequency electroacupuncture is more effective.

• Journal of Korean Academy of Nursing
• /
• v.42 no.3
• /
• pp.333-341
• /
• 2012

Purpose: The purpose of this study was to test whether pre-operative visual information and parental presence had positive effects on anxiety, delirium, and pain in pediatric patients who awoke from general anesthesia in a post-surgical stage. Methods: This study used a non equivalent control-group post test design (n=76). Independent variables were provision of pre-operative visual information and parental presence for post-surgical pediatric patients in PACU (post anesthesia care unit). Dependent variables were anxiety, delirium, and pain in the pediatric patients measured three times at 10 minute intervals after extubation in the PACU. Measurements included Numerical Rating Scale for assessing state anxiety, Pediatric Anesthesia Emergence Delirium Scale by Sikich & Lerman (2004) for delirium, and Objective Pain Scale by Broadman, Rice & Hannallah (1988) for pain. Results: Experimental group showed significantly decreased state anxiety at time points-10, 20, and 30 minutes after extubation. Delirium was significantly lower at 10 minutes and 30 minutes after extubation in the experimental group. Pain was significantly lower at 10 minutes after extubation in the experimental group. Conclusion: The results of this study suggest that this intervention can be a safe pre-operative nursing intervention for post-surgical pediatric patients at PACU.

• Research in Community and Public Health Nursing
• /
• v.14 no.2
• /
• pp.253-262
• /
• 2003

Purpose: This study was carried out to identify factors influencing osteoporosis in women at pre- and post-menopausal state. Methods: The subjects of this study were 52 pre-menopausal and 125 post-menopausal women who were assessed of bone density in one general hospital. The data were collected through review of clinical records and telephone interviews using a questionnaire. Results: In the pre-menopausal women, the factors influencing osteoporosis were regular exercise (protective factor) and age (risk factor). Regression analysis showed that the factors attributable to osteoporosis included educational level, weight, age and number of pregnancy, accounted for 41.89% of the total variance. In the post-menopausal women. the factors influencing osteoporosis were age (risk factor), low educational level (risk factor), low economical state (risk factor), high parity (risk factor), and intake of coffee (protective factor). Regression analysis also showed that factors attributable to their osteoporosis included age, educational level, number of delivery, intake of the coffee, regular exercise, number of pregnancy and duration of oral pill intake, accounted for 37.41 % of the total variance. Conclusion: In pre-menopausal women, regular exercise was one of the most powerful determinant of their bone mass. Therefore, it is necessary to participate in a regular exercise program to maintain peak bone mass density prior to the onset of menopause. In post-menopausal women, increased age was the most influencing factor of their bone mass. Therefore, it is essential to establish early diagnosis and management of osteoporosis after menopause.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.15
• /
• pp.6239-6241
• /
• 2014

Purpose: To compare the diagnostic accuracy of the neutrophil/lymphocyte ratio (NLR) with the platelet/lymphocyte ratio (PLR) in predicting malignancy of pelvic masses which are pre-operatively malignant suspicious. Materials and Methods: In this retrospective study we evaluated the clinical features of patients with ovarian masses which had pre-operatively been considered suspicious for malignancy. The patients whose intraoperative frozen sections were malign were classified as the study group, while those who had benign masses were the control group. Data recorded were age of the patient, diameter of the mass, pre-operative serum Ca 125 levels, platelet count, neutrophil/lymphocyte ratio and platelet/lymphocyte ratio. Results: There was statistically significantly difference between the groups in terms of age, diameter of the mass, serum Ca 125 levels, platelet number and platelet/lymphocyte ratio. Mean neutrophil/lymphocyte ratios showed no difference between the groups. ROC curve analysis showed that age, serum Ca 125 levels, platelet number and PLR were discriminative markers in predicting malignancy in adnexal masses. Conclusions: According to the current study, serum Ca 125 levels, pre-operative platelet number and PLR may be good prognostic factors, while NLR is an ineffective marker in predicting the malignant characteristics of a pelvic mass.

• Safety and Health at Work
• /
• v.9 no.2
• /
• pp.172-179
• /
• 2018

Background: Insufficient training in infection control and occupational health among healthcare workers (HCWs) in countries with high human immunodeficiency virus (HIV) and tuberculosis (TB) burdens requires attention. We examined the effectiveness of a 1-year Certificate Program in Occupational Health and Infection Control conducted in Free State Province, South Africa in an international partnership to empower HCWs to become change agents to promote workplace-based HIV and TB prevention. Methods: Questionnaires assessing reactions to the program and Knowledge, Attitudes, Skills, and Practices were collected pre-, mid-, and postprogram. Individual interviews, group project evaluations, and participant observation were also conducted. Quantitative data were analyzed using Wilcoxon signed-rank test. Qualitative data were thematically coded and analyzed using the Kirkpatrick framework. Results: Participants recruited (n = 32) were mostly female (81%) and nurses (56%). Pre-to-post-program mean scores improved in knowledge (+12%, p = 0.002) and skills/practices (+14%, p = 0.002). Preprogram attitude scores were high but did not change. Participants felt empowered and demonstrated attitudinal improvements regarding HIV, TB, infection control, and occupational health. Successful projects were indeed implemented. However, participants encountered considerable difficulties in trying to sustain improvement, due largely to lack of pre-existing knowledge and experience, combined with inadequate staffing and insufficient management support. Conclusion: Training is essential to strengthen HCWs' occupational health and infection control knowledge, attitudes, skills, and practices, and workplace-based training programs such as this can yield impressive results. However, the considerable mentorship resources required for such programs and the substantial infrastructural supports needed for implementation and sustainability of improvements in settings without pre-existing experience in such endeavors should not be underestimated.

• Structural Engineering and Mechanics
• /
• v.71 no.6
• /
• pp.603-625
• /
• 2019

Main cable configurations under final dead load and in the unloaded state and critical construction parameters (e.g. unstrained cable length, unstrained hanger lengths, and pre-offsets for tower saddles and splay saddles) are the core considerations in the design and construction control of a suspension bridge. For the purpose of accurate calculations, it is necessary to take into account the effects of cable strands over the anchor spans, arc-shaped saddle top, and tower top pre-uplift. In this paper, a method for calculating the cable configuration under final dead load over a main span, two side spans, and two anchor spans, coordinates of tangent points, and unstrained cable length are firstly developed using conditions for mechanical equilibrium and geometric relationships. Hanger tensile forces and unstrained hanger lengths are calculated by iteratively solving the equations governing hanger tensile forces and the cable configuration, which gives careful consideration to the effect of hanger weight. Next, equations for calculating the cable configuration in the unloaded state and pre-offsets of saddles are derived from the cable configuration under final dead load and the conditions for unstrained cable length to be conserved. The equations for the main span, two side spans and two anchor spans are then solved simultaneously. In the proposed methods, coupled nonlinear equations are solved by turning them into an unconstrained optimization problem, making the procedure simplified. The feasibility and validity of the proposed methods are demonstrated through a numerical example.

• Geomechanics and Engineering
• /
• v.27 no.6
• /
• pp.537-550
• /
• 2021

There are various technical problems need to be solved in the construction process of pre-setting an isolation wall into a double lane in the outburst prone mine. This study presents a methodology that pre-setting an isolation wall into a double lane without a coal pillar. This requires the excavation of two small section roadways to dig a wide section roadway, followed by construction of the separation wall. During this process the connecting lane is reserved. In order to ensure the stability of the separation wall, the required bearing capacity of the isolation wall is 4.66 MN/m and the deformation of the isolation wall is approximately 25 cm. To reduce the difficulty of implementing support the roadway is driven by 5 m/d. After the construction of the separation wall, the left side coal wall is brushed 1.5 m to make the width of the gas roadway reach 2.5 m and the roadway support utilizes anchor rod, ladder beam, anchor cable beam and net configuration. During construction, the concrete pump and removable self-propelled hydraulic wall mold are used to pump and pour the concrete of the isolation wall. In the process of mining, the stress distribution of coal body and isolation wall is detected and measured on site. The results demonstrate that the deformation of the surrounding rock of roadway and separation of roof in the roadway is small. The stress of the bolt and anchor cable is within equipment tolerance validating their selection. The roadway is well supported and the intended goal is achieved. The methodology can be used for reference for similar mine gas control.