• Environmental and Resource Economics Review
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• v.20 no.1
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• pp.61-98
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• 2011

This study conducts economic evaluation of alternatives for $CO_2$ reduction of thermal power plants. Two alternatives in reducing $CO_2$ emission are considered for the evaluation under the RPS(Renewable Portfolio Standard) system; one is to perform renewable energy quotas and another is to construct green thermal power plants using CCS(Carbon Capture and Sequestration). As evaluation methods, DCF(Discount Cash Flow) and ROPM(Real Options Pricing Method) are employed. At a discount rate of 7.5% applied to the Electricity Supply and Demand Plan, it is shown that green thermal power generation has economic dominance under both evaluation methods.

• The Journal of the Korea Contents Association
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• v.6 no.3
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• pp.38-45
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• 2006

A dual-level low voltage differential signalling (DLVDS) circuit is proposed aiming at reducing transmission lines for a LCD driver IC. We apply two data to the proposed DLVDS circuit as inputs. Then, the transmitter converts two inputs to two kinds of fully differential signals. In this circuit, two transmission lines are sufficient to transfer two inputs while keeping the LVDS feature. However, the circuit has a common mode bias fluctuation due to difference of the input bias and the reference bias. We compensate the common mode bias fluctuation using a feedback circuit of the current source bias. The receiver recovers the original input data through a level decoding circuit. We fabricated the proposed circuit using $0.25{\mu}m$ CMOS technology. The simulation results of proposed circuit shows 1-Gbps/2-line data rate and 35mW power consumption at 2.5V supply voltage, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.166-174
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• 2014

Fuel injection pressure has steadily increased in diesel engines for the purpose of improving fuel efficiency and cleaning exhaust gas, but it has now reached a point, where the cost for higher pressure does not warrant additional gains. Common rail systems on modern diesel engines have fuel pumps that are mechanically driven by crankshaft. The pumps actually house two pumping module inside: a low pressure pump component and a high pressure pump component. Part of the fuel compressed by the low pressure component returns to the tank in the process of maintaining the pressure in the common rail. Since the returning fuel represents pumping loss, fuel economy improves if the returned fuel can be eliminated by using a properly controled electrical fuel pump. As the first step in developing an electrical fuel pump the fuel supply system on a 6 liter diesel engine was modeled with AMESim to analyze the workload and the fuel feed rate of the injection pump, and the results served as basis for selecting a suitable servo motor and a reducer to drive the pump. A motor controller was built using a DSP and a program which controls the common rail pressure using a proportional control method based on the target fuel pressure information from the engine ECU. A test rig to evaluate performance of the fuel pump is implemented and used to show that the newly developed electrically driven fuel pump can satisfy the fuel flow demand of the engine under various operating conditions when the rotational speed of the pump is adequately controlled.

• Journal of Labour Economics
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• v.24 no.1
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• pp.67-96
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• 2001

The recent economic crisis started at the end of 1997 has brought about changes in labor market practices. One of them is rapid increase in the ratio of workers with alternative employment arrangement, so-called contingent workers. This type of arrangement, unlike traditional employment arrangement, makes employers properly adjust employment to business cycles and it also makes it possible for employees to solve time and spatial constraints related to labor supply. However, recent experience has revealed its negative characteristics such as lower wage rate, deficient fringe benefits, insufficient job security. Using the data from the first and the second wave of the Korea Labor and Income Panel Survey, this study focuses on change in the tendency of being contingent workers and decomposition of the wage differentials among regular and contingent workers by estimating the switching regression model. Results show that the recent crisis significantly contributed to probabilities of being contingent workers, especially for women, the young, the older, and the lowly educated. Decomposition shows that one quarter or one third of 35% of wage differentials are due to the price effect that the same productive characteristics are differently paid by the types of employment arrangements.

• Journal of Environmental Impact Assessment
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• v.24 no.5
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• pp.472-486
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• 2015

More than 8M tons of coal ashes are generated from coal-fired thermal power plants every year in Korea. Excluding the recycled portion (Current recycling rate: approximately 70%), all of the generated coal ashes end up in coastal landfills. Currently, the difficulties faced in establishing new ash treatment fields are attributed to the concerns raised over the environmental impacts caused by the landfills at individual plant facilities. Given the number of coal-fired thermal power plants to be built in the future (reflected in the 7th Basic Plan for Long-term Electricity Supply and Demand), building new ash treatment fields or seeking a new treatment plan seems unavoidable. Based upon a review of coal ash and its management, this study concluded that the most effective and fundamental strategy to minimize the environmental impacts resulting from coal ash landfills is to avoid constructing new coal-fired powerplants and furthermore, suggests that the practice of beneficial use and recycling the produced coal wastes should be encouraged.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.2
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• pp.101-110
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• 2007

This study was performed to find out hazardous factors in the loaded works of muscular skeletal disorders(MSDs) for four company attached to dining workers from October 2005 to June 2006. The results are summarized as follows. 1. 42.5% of workers in study group were 40-50 years old, and females were higher than males, and the average of body weight was 70kg, 57kg in males and females, respectively. Working time per day was mostly 7-9hours, and the rate of worker who had never education and training was 46%. 2. The upper part and right part of body were higher than lower part and left part in symptoms of muscular skeletal disorders. Body parts which complained of symptoms were the order of right shoulder(55%), right arm(54%), right hand,(40%) waist(35%), leg(25%), and neck(24%). 3. The results of evaluation in the loaded works of muscular skeletal disorders to cooking, dish supply, preparing side dish, and washing the dishes and cleaning the floor of cooking room using RULA and OWAS checklists was action level 4(potential hazards, needs of change workplace), and the result of evaluation using back compressive force needed control measures as 779.27 lbs~1,274.04 lbs. In a view point of the result of this study, large dining rooms should be designed by ergonomic technology for the work surface height, width, and depth. The height of carrying car should be lower to 70cm, and repetitiveness and handling weight should be reduced by mechanical means, and education and training also should be performed for all of workers positively.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.253-261
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• 2016

A variety of methods for detecting the location of an underground water pipeline are being used across the world; the current main methods used in South Korea, however, have the problems of low precision and efficiency and the limitations in actual application. On this, this study developed locator capable of detecting the location of a water pipe by the use of an IMU sensor, and technology for using the extended karman filter to correct error in location detection and to plot the location on the coordinate system. This study carried out a tract test and a road test as basic experiments to measure the performance of the developed technology and equipment. As a result of the straight line, circular and ellipse track tests, the 1750 IMU sensor showed the average error of 0.08-0.11%; and thus it was found that the developed locator can detect a location precisely. As a result of the 859.6-m road test, it was found that the error was 0.31 m in case the moving rate of the sensor was 0.3-0.6 m/s; and thus it was judged that the equipment developed by this study can be applied to long-distance water pipes of over 1 km sufficiently. It is planned to evaluate its field applicability in the future through an actual pipe network pilot test, and it is expected that locator capable of detecting the location of a water pipe more precisely will be developed through research for the enhancement of accuracy in the algorithm of location detection.

• Journal of Korean Society of Transportation
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• v.35 no.5
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• pp.375-384
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• 2017

The aim of this study is to develop evaluation indicators for parking environment in residential areas. Recently, lots of local governments in korea are implementing projects for parking environment improvement. However, there are no indicators for parking environment evaluation except for the rate of parking supply by registered cars. So, it is really difficult to prioritize projects and monitor the result of projects. Therefore, this study presents six indicators for parking environment evaluation and its weights using AHP through the survey. The result of this study proposed the assessment model for parking environment based on indicators and it was found that actual data in Incheon can be simulated in reality. And this result also is expected to help monitoring and selecting projects.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.11
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• pp.1023-1029
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• 2013

The integration between a gas turbine and an air separation unit (ASU) is important in IGCC plants. The portion of ASU air extracted from the gas turbine and the degree of nitrogen supply from the ASU to the gas turbine side are important operating parameters. Their effect on the gas turbine performance and operability should be considered in a wide ambient temperature range. In this study, appropriate nitrogen dilution rate and turbine inlet temperature that satisfy the two limitations of turbine blade temperature and maximum allowable power output were predicted. The air integration was set at zero. The simulation showed that the power output increases and turbine blade temperature decreases as the nitrogen dilution increases. The maximum allowable power output can be obtained under medium and low ambient temperature ranges. Under a high ambient temperature range, the achievable power is less than the maximum power.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.267-274
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• 2016

Sewerage supply in rural community is the important for water quality protection of water system such as river, lake and wetland. And characteristic of small scale wastewater system that have wide range of inflow and concentration in sewage should be considered for stable operation of small scale wastewater treatment plant. In this research, characteristics of flow ratio (flow / designed flow), effect on treatment efficiency of small scale wastewater treatment plant and assessment of optimal flow ratio were conducted through analysis on operation result of 18 small scale wastewater treatment plant in Bong-hwa gun. As a result, flow ratio shows the higher value during summer. However pollutants concentration in sewage was shown the higher concentration during autumn and winter. Treatment of small scale wastewater treatment plant is increased when flow ratio increased, and nutrient treatment efficiency is more sensitive to change of flow ratio than organic compound and suspended solids. According to this research result, it need to be maintained flow ratio 0.8 over value for stable treatment efficiency of small scale wastewater treatment plant.