• Journal of Biosystems Engineering
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• v.23 no.4
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• pp.365-372
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• 1998

This study was carried out to develop a nutrient-solution mixing-and-supplying system, which used a low-cost metering device instead of expensive metering pumps and a fuzzy logic controller. A low cost and precise overflow-type metering device was developed and evaluated by testing the flow discharge for the automatic nutrient-solution mixing-and-supplying system for snail-scale hydroponic sewers. The fuzzy logic controllers, which could predict and meet the desired values of EC and supply rate of nutrient solution were developed and verified by simulation and experiment. this fuzzy logic controller, whose algorithm consists of four crisp inputs, two crisp outputs and nine rules, was developed to predict the desired value of EC and supply rate of nutrient solution and two crisp inputs, one crisp output and nine rules used to control EC to the desired values. The nutrient-solution mixing-and-supplying system showed satisfactory EC control performance with the maximum overshooting of 0.035 mS/cm and the maximum settling time of 15 minutes in case of increasing 0.7 mS/cm. also, the accuracy of the overflow-type metering device in terms of the full-scale error was 2.29% when using solenoid valve only and 0.2% when using solenoid valve and flow control valve together.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.667-672
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• 2016

The goal of this study was to develop a venturi-type air bubble generator with a porous material throat. Using the two-phase multi-flow CFD analysis for the venturi tube, researchers determined the optimal design of major dimensions, such as the venturi throat length and diameter, in order to control the performance of the air bubble supply through the porous material throat in a venturi tube. Researchers then determined the relationship between the flow rate of supply water and the major design dimensions of the venturi-type air generator for maximizing the performance of the air bubble supply through the porous material throat in a venturi tube.

• Journal of Korean Academy of Nursing
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• v.24 no.1
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• pp.33-46
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• 1994

In Korea, breastfeeding practice has decreased since 1980's. According to the literature review, insufficient milk supply(IMS) is a major reason found by mothers for early termination of breastfeeding practice. Insufficient milk supply syndrome cannot be explained simply. IMS is a complex phenomenon that has never been adequately investigated in Korea. Using the modified IMS conceptual framework by Hill and Humenick(1989), a study was conducted at one well baby clinic located in metropolitan hospital. Approval was obtained from head of nursing service and employees ill the well baby clinic. The study sample was to restricted mothers who initiated breastfeeding and still continuously breastfeeding (n=52) and mothers who initiated breastfeeding but terminated at the time of data collection (n=39). Factor analysis suggested that Potential Determinant factors, maternal psychologic factors were : sociocultural factors, breastfeeding behaviors, breastfeeding frequency, social support, maternal education and prenatal preparation, physical and sibling support, maternal confidence, and maternal physicals which accounted for 71.12% of the variance. Using discriminant analysis those potential determinant factors predicted 72.49% of the cases accurately. These findings of research suggest that the modified IMS model is valid. But additional variables which consider Korea sociocultural factors may need to be included in future studies to determine and develop an IMS model for Korea.

• Health Policy and Management
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• v.11 no.2
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• pp.29-57
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• 2001

Since the inauguration of the medical insurance system in 1977, the increasing medical expenses which can be menace to tile finance of the medical insurance system, have become major concern in the medical insurance field In Korea. This study focuses on the determinants of the medical expenses in the health insurance in Korea and analyzes the impact of these factors on the increase in the medical expenses. The empirical work is done using the pooled cross-section and time-series data of the medical insurance for the self-employeds and the industrial workers from the year 1995 to 1997. The result of this study shows that the main determinants of the medical expenses in the health insurance are the ratio of the population of the aged to the total population, the frequency of the utilization, number of doctors per capita and the regime changes. Although the increasing trend in the medical expenses seems to be unavoidable, we probably need to add some efficiency to the medical expenses by suppressing the supply and the utilization of the unnecessary medical services. The fee-for-service reimbursement system of today can't suppress the supply of the unnecessary medical services effectively. So we need to convert the present fee-for-service system into DRG's which is known to reduce the medical costs. The increase in the medical expenses comes from a lot of factors. Therefore, we should develop more systematic and comprehensive measures to control the soaring medical expenses in consideration of the various factors such as demand, supply, and the organizational side of the medical system.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.561-564
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• 2007

FCEV uses electric energy which generated from the reaction between Hydrogen and Oxygen in fuel cell stack as driving force. As fossil fuels are exhausted, fuel cell is regarded as a potent substitute for next generation energy source, and thus, most of car-makers make every efforts to develop fuel cell electric vehicle (FCEV). In addition, fuel cell is also beneficial in aspect of environment, because only clean water is produced during chemical reaction process instead of harmful exhausted gas. Generally, Hydrogen is supplied from high-pressured fuel tank, and air blower (or compressor) supply Oxygen by pressurizing ambient air. Air blower which is driven by high speed motor consumes about $7{\sim}8$ % of energy generated from fuel cell stack. Therefore, the efficiency of an air blower is directly linked with the performance of FCEV. This study will present the development process of an air blower and its consisting parts respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.577-580
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• 2000

The aim of this paper is to develop a high stable measuring device for radioactive pulses. The device consists of a high voltage supply unit using a fly-back converter principle, and a pulse detection unit for gamma-rays and neutrons. The high voltage supply unit designed can generate DC voltage up to 1,500v at 5V-input, and have a series voltage regulator to maintain the output voltage constantly, resulting in less than 1.63% of voltage regulation. The pulse detection parts consists of an active integrator, a pole-zero circuit, and a 3-stage amplifier of 60 dB, and its frequency bandwidth is from 37 Hz to 300 kHz. From the experimental results, it is confirmed that the measuring device can count at least 10,000 pulses in a second.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.284-290
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• 2006

For the case of high head and critical low flow rate range of micro hydropower resources, it requires very low specific speed turbines which are lower than conventional impulse turbine's specific speed. In order to satisfy the request for very low specific speed turbine with high efficiency, a new positive displacement turbine is developed. The performance characteristics of the new turbine is tested and compared with a conventional impulse turbine, which is used for automatic water faucet system. The purpose of present study is to develop an high performance turbine that can be used to extract micro hydropower potential of a water supply system. The test results show that the positive displacement turbine is much more efficient than the conventional turbine and it can sustain high efficiency under the wide range of operating conditions. The pressure pulsations at the inlet and outlet of the positive displacement turbine can be considerably minimized by using simple pressure damper.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1159-1165
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• 2010

This paper describes an energy efficient train control. In these days, the researchers develop the energy efficient railway technologies, such as energy storage system, energy efficient driving. Mass rapid transit (MRT) railways, which are an important means of public transportation in urban areas, have operational characteristics that include short headways, frequent departures and arrivals. Therefore, when multiple trains are operating in the same power supply system, it is important to synchronize the energy tractions and regenerations. This paper define the group of trains for energy saving according to a power supply. We analyze the current synchronized driving situations and estimate the effect.

• The Journal of the Korean dental association
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• v.47 no.3
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• pp.122-130
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• 2009

For the successful guided bone regeneration(GBR) of maxillary bony defect, proper soft tissue coverage is one of the most important things. Soft tissue dehiscence can be most common reason of osseous reconstruction failure. If a vascular supply to the graft should not develop from the host tissue, then the graft may also foil. Both of these prerequisites can be aided by judicious use of the buccal fat pad(BFP). Many methods for adequate soft tissue coverage have been proposed and the use of the BFP is one of them. BFP is useful in posterior maxillary area, can cover larger area and have higher blood flow than other methods. so the use of the BFP may offer protection and early blood supply to maxillary bone graft. This report describes the history, anatomy, blood flow, and clinical usefulness with two clinical cases.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.782-788
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• 2008

Present Prices have reduced to $100 per barrel, but international oil prices caused big damage to local logistics industry due to rise in International oil prices and, in august 2008 oil prices reached up to 146 US. Depending on oil prices, the domestic logistic industry should develop a strategy by innovative management of purchase of supply for manufacturing industry and efficient supply and demand of resources which is believed to be more important. Accordingly, we want to analyze railroad logistics' present condition and effect on railroad industry that can expect affirmative development by oil-price rise and by developing strategies for efficient railroad logistics.