• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2007년도 추계종합학술대회
• /
• pp.681-684
• /
• 2007

This paper proposed and designed I-PD Controller using Shunji Manabe's CDM. The designed controller is applied to a level control system. The designed I-PD controller is smaller steady state error and get a specific response. A simulation results, the designed controller was better than a Fuzzy I-PD controller on a level control system.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제2권2호
• /
• pp.146-152
• /
• 2002

Mold level control has been a major control task for continuous casting plants. The system involves nonlinearities such as stick-slip friction in the sliding gate, time-delay, friction force variations between molten steel and the inner wall of mold, and nozzle logging/unclogging. These complex problems should be solved to control mold level for steel cast. In this paper, we propose a neural fuzzy mold level control technique for solving these complex problems and give experiment studies to show the mold level control in continuous casting process.

• 한국직업건강간호학회지
• /
• 제19권2호
• /
• pp.150-158
• /
• 2010

Purpose: The purpose of this study was to investigate stress-coping level and to determine the significant predictor of nurses' stress-coping in schoolwork. Methods: This study was based on the questionnaire survey carried out among 340 nurses in schoolwork at Korea National Open University. The questionnaire included the general factor, schoolwork related factor, health related factor, work related factor, stress level and stress-coping level. The data were analyzed using descriptive statistics, t-test, ANOVA, Pearson's correlation coefficient, and multiple regression analysis. Results: The mean score of stress-coping level was 2.23 (SD=0.27). Time for study, exercise, and work as well as stress on daily life and job stress were significant predictors of nurses' stress-coping level in schoolwork. Conclusion: Findings of this study can be an important resource to improve stress-coping strategies of nurses in schoolwork.

• 전기학회논문지
• /
• 제67권2호
• /
• pp.209-215
• /
• 2018

This paper present a 7-level PWM inverter adopting voltage balancing control to series-connected input capacitors. The prior proposed 7-level PWM inverter consists of dc input source, three series-connected capacitors, two bidirectional switch modules, and an H-bridge. This circuit topology is useful to increase the number of output voltage levels, however it fails to generate 7-level in output voltage without consideration for voltage balancing among series-connected capacitors. Capacitor voltage imbalance is caused on the different period between charging and discharging of capacitor. To solve this problem, we uses the amplitude modulation of carrier wave, which is used to produce the center output voltage level. To verify the validity of the proposed control method, we carried out computer-aided simulation and experiments using a prototype.

• 전기학회논문지
• /
• 제63권2호
• /
• pp.325-330
• /
• 2014

In order to operate trains both mainline railroad platform and metropolitan subway line platform, it is necessary to develop the door step equipment of the rolling stock regardless of low(500mm, mainline) and high level platforms(1,135mm, metropolitan subway line) because of the requisite door safety system. In this study, TMS-DCU interface is studied for low and high level railway platforms. As a result, Design circuit of TMS(Train Management System)-DCU(Door Control Unit) interface is suitable for telescopic sliding type doorstep unit to minimize damage to the carbody underframe of railway vehicles.

• 시스템엔지니어링학술지
• /
• 제12권2호
• /
• pp.47-57
• /
• 2016

As the inventory costs of repairable items in military logistics continue to increase, many studies for optimal inventory level of these items are being carried out in advanced countries, including the US, to reduce these costs. Research on inventory level optimization for repairable items aimed to achieve the availability goal of a system with a MIME(Multi Indenture Multi Echelon) repair policy structure first began with Sherbrooke's METRIC and developed into various types. This research is to analyze and compare recent V-METRIC related studies to search for another variation in this field. This paper mainly looks at how to determine optimum inventory level for each repairable item to achieve a specific availability target within a limited budget, and also how to minimize inventory cost while achieving its availability target by determining optimal inventory level of each repairable item.

• Journal of Preventive Medicine and Public Health
• /
• 제35권1호
• /
• pp.76-82
• /
• 2002

Objective : To investigate the relationships of occupational class, educational level and deprivation with mortality in Korea Methods : This study used existing South Korean national data on occupation, educational level, and deprivation and death. Mortality was investigated using registered death data from 1993 to 1997 obtained from the Korean National Statistics Office (NSO) with denominators drawn from the 1995 Census. Statistical analysis consisted of poisson regression modeling and multilevel analysis. Results : The lower occupational class (manual workers) group had a higher mortality rate than the higher occupational class (non-manual workers) group Educational level, and deprivation were both inversely related withand mortality. Occupation was strongly associated with education. Area-based deprivation indicators and individual indices for social class made an independent contribution to the mortality risk. Conclusions : The findings of this study suggests that the relationships of occupational class, educational level and deprivation with mortality appears to be stronger in Korea than in European countries.

• Journal of Preventive Medicine and Public Health
• /
• 제47권5호
• /
• pp.273-280
• /
• 2014

Objectives: To evaluate the occurrence of patient adverse events in Korean hospitals as perceived by nurses and examine the correlation between patient adverse events with the nurse practice environment at nurse and hospital level. Methods: In total, 3096 nurses working in 60 general inpatient hospital units were included. A two-level logistic regression analysis was performed. Results: At the hospital level, patient adverse events included patient falls (60.5%), nosocomial infections (51.7%), pressure sores (42.6%) and medication errors (33.3%). Among the hospital-level explanatory variables associated with the nursing practice environment, 'physician-nurse relationship' correlated with medication errors while 'education for improving quality of care' affected patient falls. Conclusions: The doctor-nurse relationship and access to education that can improve the quality of care at the hospital level may help decrease the occurrence of patient adverse events.

• 치과방사선
• /
• 제23권2호
• /
• pp.215-226
• /
• 1993

The purpose of this study was to investigate the effects of the low level irradiation on the mitotic index of the basal cells in the buccal pouch of hamsters{golden hamster: APG strain). After colchicine was administrated to the hamsters through the intraperitoneal, the low level radiation{5460mR) was exposed on the buccal pouch of hamsters. The mitotic index of the basal cells was estimated 2 hours after irradiation. The results were as follows: 1. The mean mitotic index of the control group was 4.32. 2. The mean mitotic index of the irradiated group was 2.46. 3. T-test of data in the irradiated group showed significant difference from the mitotic index in the control group. These results suggested the lowered mitotic index of the irradiated group resulted from the low level irradiation.

• Nuclear Engineering and Technology
• /
• 제36권1호
• /
• pp.73-82
• /
• 2004

The deaerator of a power plant is one of feedwater heaters in the secondary system, and it is located above the feedwater pumps. The feedwater pumps take the water from the deaerator storage tank, and the net positive suction head(NSPH) should always be ensured. To secure the sufficient NPSH, the deaerator tank is equipped with the level control system of which level sensors are critical items. And it is necessary to ascertain the sensor state on-line. For this, a model-based fault detection and diagnosis(FDD) is introduced in this study. The dynamic control model is formulated from the relation of input-output flow rates and liquid-level of the deaerator storage tank. Then an adaptive state estimator is designed for the fault detection and diagnosis of sensors. The performance and effectiveness of the proposed FDD scheme are evaluated by applying the operation data of Yonggwang Units 3 & 4.