• 대한전기학회논문지:전력기술부문A
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• 제55권10호
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• pp.399-409
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• 2006

This paper presents a novel method for satisfying the thermal comfort of indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. Korea Electric Power Corporation (KEPCO) use the fixed duty cycle control method regardless of the indoor thermal environment. However, this method has disadvantages that energy saving depends on the set-point value of the Air-Conditioner and direct load control (DLC) has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. In this paper, the variable duty cycle control method is proposed in order to compensate the weakness of conventional fixed duty cycle control method and improve the satisfaction of residents and the reduction of peak demand. The proposed method estimates the predict mean vote (PMV) at the next step with predicted temperature and humidity using the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. To verify the effectiveness of the proposed variable duty cycle control method, the case study is performed using the historical data on Sep. 7th, 2001 acquired at a classroom in Seoul and the obtained results are compared with the fixed duty cycle control method.

• 대한기계학회논문집A
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• 제32권5호
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• pp.402-410
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• 2008

The heavy duty diesel engine must have a large output for maintaining excellent mobility. In this study, a three dimensional finite element model of a heavy-duty diesel engine was developed to conduct the stress analysis. The FE model of the heavy duty diesel engine main parts consisting with four half cylinder was selected. The heavy duty diesel engine parts includes with cylinder block, cylinder head, gasket, liner, bearing cap, bearing and bolts. The loading conditions of engine were pre-fit load, assembly load, and gas load. As the results of structural analysis, because the stress values of cylinder block and bearing cap did not exceed the basic design can be satisfied. But on the part which contacts with cylinder block and bearing cap the stress value exceeds the allowable strength of material. In order to decrease the stress at that part, it was optimized with parametric study.

• 통상정보연구
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• 제10권3호
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• pp.143-162
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• 2008

The Title 19 of the U.S. Code covers custom duties and is the heart of international trade regulation in the U.S.. Among the provisions in Title 19, is Chapter 4, the Tariff Act of 1930. Under U.S. Antidumping duty law, dumping occurs when `subject merchandise' is imported into the U.S. and sold at less than `fair value.' The administration of U.S. Antidumping duty law is shared between the Department of Commerce('Commerce') and International Trade Commission('USITC'). The U.S. Court of International Trade ("CIT") and the U.S. Court of Appeals for the Federal Circuit ("CAFC") decided the review of antidumping duty ("AD") determinations and administrative review results issued by the Commerce and the USITC, as well as the review of countervailing duty ("CVD") decisions. In Eurodif S.A. v. United States, the CAFC considered the important issue of whether the antidumping and countervailing duty laws apply to sales and purchases of services--in this case, the sale or purchase of enrichment services. Although the federal courts had considered the issue of whether a sale of enrichment services constitutes a sale of goods, the issue had never arisen in the context of the antidumping and countervailing duty laws. Also this is the first time that the Supreme Court has ever agreed to consider an antidumping case.

• Safety and Health at Work
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• 제15권1호
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• pp.102-109
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• 2024

Background: In today's modern world, longer working hours, shift work, and working at night have become major causes of the disruption of our natural circadian rhythms. This study aimed to investigate the effects of the type of shift work (rotating vs. fixed day), duty period (on-duty vs. off-duty), and working period within each shift (nighttime vs. daytime) on the circadian rhythm characteristics of nurses who provide direct patient care. Methods: This cross-sectional study used a purposive sampling method. Cosinor analysis was applied to analyze the actigraphy data of nurses providing direct patient care for seven consecutive days. The linear mixed effects model was then used to determine any variances between shift type, duty period, and working period within each shift for the nurses. Results: The mesor value did not differ according to nurses' shift type, duty period, and working period within each shift. The amplitude was statistically higher in on-duty nurses and in daytime working hours. The acrophase was significantly delayed in nighttime working hours. As well as nurses in rotating shift had experience. Conclusion: Our findings revealed that the peak activity of nurses occurs significantly later at night while working and nurses working during nighttime hours may have a weaker or less distinct circadian rhythm. Thus, this study suggests that limits be placed on the number of rotating nighttime shifts for nurses.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.145-147
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• 2005

This paper presents a methodology for satisfying the thermal comfort of Indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. KEPCO(Korea Electric Power Corporation) use the fixed duty cycle control method regardless of the indoor thermal environment. This method has disadvantages that energy saying depends on the set-point value of the Air-Conditioner and DLC has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. A variable duty cycle estimates the PMV(Predict Mean Vote) at the next step with a predicted temperature and humidity coming from the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. The proposed methodology uses the historical real data of Sep. 7th, 2001 from a classroom in seoul to verify the effectiveness of the variable duty cycle method comparing with fixed duty cycle. The result shows that the variable duty cycle reduces the peak demand to 2.6times more than fixed duty cycle and increases the load control ratio by 8% more. Based on the variable duty cycle control algorithm, the effectiveness of DLC is much more improved as compared with the fixed duty cycle.

• 제어로봇시스템학회논문지
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• 제17권12호
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• pp.1273-1277
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• 2011

This paper proposes a control-based approach for duty cycle adaptation in wireless sensor networks. The proposed method, QCon, controls duty cycle through queue management in order to achieve high performance under variable traffic rates. To minimize energy consumption while meeting delay requirement, we design a feedback controller, which adapts the sleeping time according to dynamically changing traffic by constraining the queue length at a predetermined value. Based on control theory, we analyze the adaptive behavior of QCon and derive conditions for system stability. Results from asymptotic analysis and simulations indicate that QCon outperforms existing scheduling protocol by achieving more energy savings while satisfying delay requirement.

• 센서학회지
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• 제25권5호
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• pp.303-309
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• 2016

In this paper, we introduce a new method for controlling the illumination of LEDs in visible light communication (VLC) by changing the duty cycle of Manchester code. When VLC data were transmitted in Manchester code, the average optical power of the LEDs was proportional to the duty cycle. In experiments, we controlled the illumination of a $3{\times}3$ LED array from 10% to 90% of its peak value by changing the duty cycle of the Manchester code. The synchronizing clocks required for encoding and decoding the Manchester code were supplied by pulse generators that were connected to a 220 V power line. All pulse generators made the same pulses with a repetition frequency of 120 Hz, and they were synchronized with the full-wave rectified voltage of the power line. This scheme is a very simple and useful method for constructing indoor wireless sensor networks using LED light.

• Corrosion Science and Technology
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• 제20권2호
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• pp.45-51
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• 2021

In this work, we describe the effect of pulse anodizing duty ratio on the corrosion resistance of anodic films in magnesium AZ31B. The process involves the application of square pulse potential for a constant period with a duty ratio varying from 40, 60 and 80%. In several samples, a sealing treatment for 30 minutes was conducted after anodization in order to seal the pores available in the anodic layer. After anodizing, the surface morphology of the anodic layer was examined using a scanning electron microscope (SEM Hitachi SU3500). The corrosion characteristics of the sample were evaluated through an open circuit potential (OCP) and potentiodynamic polarization test using potentiogalvanostat. SEM observation shows that the increase of anodization duty ratio (α) results in a more uniform anodic layer, with fewer pores and cracks. The increase of duty ratio (α) decreases the OCP value from approximately -1.475 to about -1.6 Volt, and significantly improves the corrosion resistance of the anodic coating by 68%. The combination of anodization and sealing treatment produces an anodic coating with a very low corrosion rate of 4.4 mpy.

• Journal of Korea Trade
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• 제23권5호
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• pp.66-86
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• 2019

Purpose - This paper describes the use of trade preferences under the EU-Korea free trade agreement (FTA) and empirically examines potential reasons for the less than full use, using data on daily EU imports from Korea at the product level. Design/methodology - We employ a probit model to analyse the relationship between the use of trade preferences on the one hand and variables such as potential duty savings, rules of origin and the characteristics of the good traded (intermediate input or final product) on the other. Findings - The paper finds that EU imports from Korea make good use of trade preferences with an overall preference utilisation rate of close to 90% in 2016, which is up from about 80% in 2012. It further shows that potential duty savings influence preference utilisation positively and that more than one quarter of the observations in our sample made use of preferences under EU-Korea FTA in 2012, despite duty savings standing at €10 or less. Originality/value - The finding that a non-negligible share of observations use preferences even when the duty savings are low has not yet figured in the literature. We further show how preference utilisation rates differ by importing EU Member State and by section of the Harmonised System and estimate the marginal impact of an increase in potential duty savings on the preference utilisation rate by broad product group, which is novel.

• 대한방사선기술학회지:방사선기술과학
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• 제20권1호
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• pp.71-75
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• 1997

This study was Investigation that we will become aware of the scattering dose of duty station and TLD value of the radiation exposure by the radiation technologists based on the university hospital located in Kwang ju. The results are followings ; 1. The air of scattering dose in chest, when the number of objects are large, is 2.0 mR in P-A and 4.6 mR in Lat. at the back of X-ray tube 2. Radiologists, radiation exposure in duty station Is 0.22 mSv to 1.96 mSv in general examination, 0.22 mSv to 1.12 mSv in contrast and special examination, 0.26 mSv to 30.96 mSv in angiography, and 0.22 mSv to 0.40 mSv in C.T 3. The value of workig condition reveals 85.5% in general examination, 6% in contrast and special examination, and 5.8% in C.T. When the annual exposure is over 20 mSv, it must be measured again according to ICRP public 60.