• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.101-110
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• 1997

The circuit effects due to the transformer primary side series equivalent inductance in the Zero Voltage Switching Pulse Width Modulated Half Bridge DC/DC Converter and its impact on the effective duty are analyzed. The steady state equations and the small signal model of the converter are derived incorporating the effects of the complementary control and the utilization of transformer primary side series equivalent inductance. The open plant dynamics are analyzed on the basis of the model derived. The model predictions are confirmed by experimental measurements.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1225-1228
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• 2011

This paper presents an advanced energy saving algorithm in building. It is important to aggregate a various demand side resource which is controllable on demand response environment. Previous demand side algorithm for building is restricted on peak power. In this paper, we suggest duty cycle algorithm for AHU on demand response to reduce the quantity of building power consumption. The test results show that the proposed algorithm is very effective.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.11 s.158
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• pp.1589-1597
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• 2006

Nowadays, Korean consumers prefer drum-type washing machines to pulsator-type washers. Washing is a complex process involving the interaction of numerous physical and chemical influences. The main factors in the washing operations are the washing chemistry of the detergent along with the mechanical input, the wash temperature, and the time provided by the washing machine. Heavy-duty detergents that are used in drum-type washing machines contain different components from those used in vertical-axis washing machines. The bath ratio and the mechanical actions to which laundry is subjected are different between the drum-type and the vertical-axis washing machines. In this study we examined the effects of wash temperature, wash time, detergent concentration, and revolution speed on the removal of soils from artificially soiled cloths in a drum-type washing machine with heavy-duty commercial detergent. We used multiple regression analyses to find the relative importance of the factors and the optimum washing conditions. The results of these experiments showed that the washing temperature was the most important factor in the effective removal of most soils. This was followed by the washing time, the detergent concentration, and finally the revolution speed. In this study it was found that superfluous amounts of detergent did not sufficiently increase the soil removal rate. Koreans who are used to washing with cold water should increase the wash time to launder more efficiently.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.6
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• pp.562-572
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• 2015

$NO_x$ emissions from diesel vehicles have been regarded as a main cause of high $NO_2$ concentration in metropolitan area. Recent studies have shown that the on-road $NO_x$ emissions of diesel vehicles are quite higher than the emission limits specified with the pre-defined test method for emission certification. To reduce air pollutants effectively, the discrepancy of emissions in certification and real-driving conditions should be tackled. In this study, the real-driving emissions have been estimated with portable emission measurement system (PEMS). The results of this study have shown that the on-road $NO_x$ emissions from diesel vehicles have been decreased as the introduction of stricter emission regulation, EURO-6, but additional reduction should be still required and robust technologies should be applied to control $NO_x$ in real-driving conditions. RDE-LDV (Real Driving Emission - Light Duty Vehicles) test method being developed in the European Union can represent excessive on-road $NO_x$ emissions of diesel vehicles as applied emission technologies and can be a solution to remove discrepant $NO_x$ emissions between certification and Korean real-driving conditions. Among the $NO_x$ reduction technologies for EURO-6 diesel vehicles, selective catalytic reduction (SCR) system has shown the better performance than lean $NO_x$ trap (LNT) system to control on-road $NO_x$ emissions. Implementing RDE-LDV will require vehicle manufacturers to adopt the more effective $NO_x$ reduction technology in real driving conditions.

• The Journal of Korean Academic Society of Nursing Education
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• v.9 no.1
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• pp.94-102
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• 2003

The purpose of this study was to identify the effects of foot-bath on fatigue of nursing students in clinical practice. method: The research design was a nonequivalent control group pretest-posttest design. The subjects were randomly assigned to one of four groups and data collection was conducted from June to August 2001. For the experimental group the foot-bath was performed once a day for 3 days. The instrument was subjective fatigue scale and 150mm graphic rating scale. For four groups pretest was done on first day and posttest was done on third day. The data was analyzed by the t-test and paired t-test. results: The subjective fatigue scale score was not significantly after the foot-bath in day duty but significantly lower after the foot-bath in evening duty. The graphic rating scale score was significantly lower after the foot-bath. The subjective fatigue scale score and graphic rating scale score on 1st, 3rd foot-bath day were significantly lower in experimental group. conclusion: On the basis of the above findings, this study suggests that foot-bath can be an effective fatigue relieving method.

• Korean Journal of Health Education and Promotion
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• v.21 no.1
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• pp.25-43
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• 2004

This study is aimed at determining stress and the degree of stress coping among nurse as well as such general characteristics as daily life styles, duty, and socio-demographic characteristics of that group. 525 nurses, from four university hospitals in Daejeon city underwent a self-administered questionnaire during the 3-week period from July. 21 to August. 9, 2003. The questions focused on general characteristics including： socio-demographic and duty characteristics, daily life styles, and stress and methods of coping with stress. Based on the distribution of degree of stresses, 66.1% of the study subjects were at the potential risk of stress, with the high risk group constituting 30.3% and the normal group 3.6%. The stress and the degree of stress coping were shown to be affected by socio-demographic and job-related characteristics as well as daily life styles. The group at higher risk of stress was shown to have a lower degree of coping with stress, implying that a lower degree of coping with stress would in turn heighten the occurrence of stress. Therefore, it is required to develop an effective strategy that includes stress-reduction programs available in the field and prompting further build-up of comprehensive stress-management programs.

• Structural Monitoring and Maintenance
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• v.7 no.1
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• pp.13-25
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• 2020

One of the most important aspects in structural health monitoring is the detection of fatigue damage. Structural components such as heavy-duty bolts work under high dynamic loads, and thus are prone to accumulate fatigue damage and cracks may originate. Those heavy-duty bolts are used, for example, in wind power generation and mining equipment. Therefore, the investigation of new and more effective monitoring technologies attracts a great interest. In this study the acoustic emission (AE) technology was employed to detect incipient damage during fatigue testing of a M36 bolt. Initial results showed that the AE signals have a high level of background noise due to how the load is applied by the fatigue testing machine. Thus, an advanced signal processing method in the time-frequency domain, the Hilbert-Huang Spectrum (HHS), was applied to reveal AE components buried in background noise in form of high-frequency peaks that can be associated with damage progression. Accordingly, the main contribution of the present study is providing insights regarding the detection of incipient damage during fatigue testing using AE signals and providing recommendations for further research.

• Journal of Korean Physical Therapy Science
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• v.10 no.2
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• pp.153-162
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• 2003

The purpose of this study was to examine the working condition of physical therapists and the degree of job satisfaction. This study also was to identify the causes of job stress: to examine job stress and job satisfaction; and to find factors that affect job satisfaction for physical therapists in Korea. A self-administered questionnaire survey was conducted from February 17 to March 15 in 2003. Survey data was obtained from 255 therapists registered in Korean Physical-Therapists Association. Results were as follows: 1. The degree of job satisfaction was moderate. 2. The degree of stress with their work was a little high. 3. Duty itself is one of the main factors of job stress of physical therapists. Working atmosphere and the relationships with job colleagues turned to be closely related to the degree of satisfaction. 4. The longer their total term of service was and the older they are, the greater the satisfaction with work was. In conclusion, the physical therapists can be encouraged to do their work more energetically and voluntarily. At the same time, the feeling of mission can also grow by shortening of working hours, reducing the quantity of work, and offering more salary. It is also to recommend an effective performance of duty and the development of their medical service to be introduced.

• Environmental Engineering Research
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• v.20 no.4
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• pp.397-402
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• 2015

SCR has been popularly approved as one of the most effective means for NOx emission control in heavy-duty and medium-duty vehicles currently. However, high urea dosing would lead to ammonia slip. And $NH_3$ sensor for vehicle emission applications has not been popularly used in real applications. This paper presents experimental studies on the diesel engine urea-SCR system by using a double NOx sensor system that is arranged in the downstream of the SCR catalyst based on ammonia cross-sensitivity. It was shown that the NOx conversion efficiency rised as $NH_3/NOx$ increases and the ammonia slip started from the $NH_3/NOx$ equal to 1.4. The increase of temperature caused high improvement of the SCR reaction rate while the space velocity had no obvious change. The ammonia slip was in advance as catalyst temperature or space velocity increase and the ammonia storage reduced as catalyst temperature or space velocity increase. The NOx real-time conversion efficiency rised as the ammonia accumulative storage increase and reached the maximum value gradually.

• The KIPS Transactions:PartC
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• v.13C no.6 s.109
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• pp.725-732
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• 2006

RBAC(Role-Based Access Control) has advantages in managing access controls, because it offers the role inheritance and separation of duty in role hierarchy structures. However, RBAC does not process delegation of permission effectively that occurs frequently in the real world. This paper proposes an Advanced Permission-Based Delegation Model(APBDM) that guarantees permanency of delegated permissions and does not violate security principle of least privilege and separation of duty. APBDM, based on the well-known RBAC96, supports both user-to-user and role-to-role delegation. A delegator can give permission to a specific person, that is delegatee, and the permission can be withdrawn whenever the delegator wants. Our model is analyzed and shown to be effective in the present paper.