• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.98-100
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• 1999

This paper presents very simple driving system for blower of separator. The system be driven by V/F control. The load of the system have hardly variation during steady state, because of fan load. We have studied about the property of the fan load in order to develop driving system for blower of separator. This study can get reduction of energy, high separation rate of a raw of tobacco and high quality.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.355-358
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• 1996

Electrical Power System (EPS) of Electric Vehicle which consists of batteries, motor and driving subsystem, has been modeled. A battery model is modeled with an electrical circuit representing a characteristics of real battery. Driving subsystem is modeled as three different level namely exact, average and functional models. Load profile includes road information, speed profile and EV mechanical parameters, which are incorporated into a reference torque in the driving subsystem model. A system model is integrated to simulate the performance of electric vehicle such as energy balance, battery status, and electrical stress of each subsystem.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.95-99
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• 2001

As a way to use energy effectively, the present study is aimed at investigating the performance characteristics of a Single Effect LiBr/Water Absorption Refrigerator using a low temperature driving heat-source. It was carried out by changing the driving heat-source temperature, the cold water outlet temperature(the refrigeration load), the cooling water inlet temperature, and the weak solution flow rate and this study compares the performance characteristics of refrigerator against the existence and non-existence of the Recirculation of the Weak solution which is used as a method to improve the performance of refrigerator. In case of Recirculation of the weak solution, more improved the Refrigeration Capacity and COP was obtained, and these effects became more larger in the high temperature of driving heat-source and large quantity of solution.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.551-554
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• 2006

An inverter system which consists of three bi-directional buck-boost converters, is proposed for motor driving. Three phase sinusoidal output voltages can be generated by utilizing three buck-boost converters. The advantage of this scheme is that it does not require a separate DC-DC converter for motor driving, i.e. inverter function is combined into the three DC-DC converters. This topology is suitable for inverters for hybrid or fuel cell vehicles where DC link voltage is subject to change depending upon charging status or output power. So the proposed system is capable of driving motor at high speed. The converter system is controlled by PI controller and simulation results done by MATLAB SIMULINK are provided.Ҙ?⨀ሉȀ̀㘰々K䍄乍?ጊ츀Ѐ㔹〻Ԁ䭃䑎䴀

• Journal of Auto-vehicle Safety Association
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• v.15 no.4
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• pp.58-64
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• 2023

The adoption of hydrogen-powered Elec is expanding globally. Hydrogen is recognized as a potentially hazardous energy source, and safety assessment is crucial for the development of plans to supply hydrogen-powered electric buses. Hydrogen gas leakage can have a significant impact during bus operations, and continuous hydrogen leakage in hydrogen-powered vehicles can result in fatal accidents. In this study, information about hydrogen leakage is collected through sensors installed within the vehicles and is measured when the sensor detects a leak. The study also proposes the use of Pseudo Fuel Leakage (PFL, %) as an additional indicator for evaluating and monitoring hydrogen safety and leakage.

• Korean Journal of Community Nutrition
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• v.7 no.3
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• pp.316-326
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• 2002

This study was carried out on 178 bus drivers in the Masan area to investigate their health and nutritional status. THe nutritional status of the subjects was surveyed using a self-administered questionnaire, and blood analyses were conducted through annual health examinations in June, 1999. The results were as fellows: About 51% were classified as normal, 33% as health-concerned, and 17% as disease-suspected. The levels of total seam cholesterol were significantly higher in the over 20 year group (194.64 $\pm$ 41.42 mg/dl) than in the under 10 year group (175,00 $\pm$ 31.33 mg/dl) with respect to the length of their driving careers. Systolic blood pressure (SBP) was significantly higher in the 51 to 60 age group than in the other groups (p < 0.05) . The total seam cholesterol increased with increasing age (p < 0.001), and SBP increased with increasing Body Mass Index (BMI) (p < 0.001). Diastolic blood pressure (DBP), total cholesterol (p < 0.01), hemoglobin (p < 0.05) and glutamate-pyruvate-aminotransferase (GPT) (p < 0.05) were significantly higher in the BMI of over 20, than in the BMI under 20. The GPT was significantly higher in the BMI over 25 than in the BMI under 25. In The mean daily energy intake was 1912.7 kcal (76.5% of the RDA) ultra the protein intake was 74.3 g (106.2% or the RDA). Compared with the recommended allowance, the energy, calcium, thiamin, and riboflavin intakes were below, and the Fe, vitamin A, vitamin C intakes were above the Korean RDA. The average carbohydrate, protein, fat ratio of energy intake was 66 : 15 : 19, respectively. The length of their driving careers had a positive correlation with their ages and total serum cholesterol levels, and their ages had a positive correlation with their blood pressures, total seam cholesterol and hemoglobin levels and BMI. Their BMI had a positive correlation with their ages, blood pressures, total serum cholesterol, hemoglobin, GPT and GOT levels. The results of this study indicate that bus drivers needed regular exercise, and control of their body weights to prevent chronic diseases, and that their health status should be monitored as the length of their driving careers and ages increase.

• Plant Journal
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• v.4 no.3
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• pp.60-65
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• 2008

Power plant industry has been developed at high-capacity, high-technology, and innovation. Steam turbine became the most useful equipment that dominate more than 50% of all the world electricity production. And developed new materials of the turbine blade and extended length of the turbine last blade brought reform in steam turbine performance upgrade. In this paper, when do partial load driving in high-capacity steam turbine, optimum driving method found whether there is something. In operating steam turbine, there is a lot of loss from secondary wake and throttle of the 1st stage nozzle by the biggest leading factor that load fluctuation affects in high-pressure steam turbine performance. Effect of internal efficiency by 1 stage nozzle is the biggest here, but here fluid flow and flow analysis were not yet examined closely definitely. So, Analyzed design data and acceptance performance test result to applying subcritical pressure drum type 560 MW, supercritical-pressure once through type 500 MW, and 800 MW steam turbines actually. In conclusion, at partial load driving, partial arc admission(PAA) is more efficient than full arc admission(FAA) efficiency. This is judged by because increase being proportional with gross energy of stream that is pressure - available energy if pressure of stream that is flowed in to the turbine increases, available energy becomes maximum and turbine efficiency improves. Therefore, turbine performance is that preview that first stage performance fell if decline is serious in partial load because first stage performance changes according to load.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.2
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• pp.45-56
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• 2021

In platoon driving, several autonomous vehicles communicate to exchange information with each other and drive in a single cluster. The platooning technology has various advantages such as increasing road traffic, reducing energy consumption and pollutant emission by driving in short distance between vehicles. However, the short distance makes it more difficult to cope with an emergency accident, and accordingly, it is difficult to ensure the safety of platoon driving, which must be secured. In particular, the unexpected situation, i.e., variability that may appear during driving can adversely affect the safety of platoon driving. Because such variability is difficult to predict and reproduce, preparing safety guards to prevent risks arising from variability is a challenging work. In this paper, we studied a simulation method to avoid the risk due to the variability that may occur while platoon driving. In order to simulate safe platoon driving, we develop diverse scenarios considering the variability, design and apply safety guards to handle the variability, and extends the detail functions of VENTOS, an open source platooning simulator. Based on the simulation results, we have confirmed that the risks caused form the variability can be removed, and safe platoon driving is possible. We believe that our simulation approach will contribute to research and development to ensure safety in platoon driving.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.197-204
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• 2004

An accumulator in hydraulic systems stores kinetic energy during braking action, and then that controls hasty surge pressure. An energy recovery system using accumulator seems to be advantageous for ERBS due to its high energy density. This study suggests a method to decide suitable accumulator volume for ERBS. The method is based upon energy conservation between kinetic energy of moving inertia and elastic energy of accumulator. The energy conversion was analyzed and a simple formula was derived. Also accumulator tests were conducted for different load mass and motor speed. A series of test work were carried out in the laboratory and the dynamic characteristics of the hydraulic motor system, such as the surge pressure and response time, were investigated in both brake action and acceleration action and these results show that the proposed design is effective for decision accumulator volume in ERBS.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.469-476
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• 2001

The Ν-value in the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the doughnut hammer with the hydraulic lift system and the automatic trip hammer system were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA) . The rod energy ratio, ΕR$\_$r/ was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ΕR$\_$r/ also varies according to the energy instrumentation system and the analysis methods.