• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.180-184
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• 2016

Legislative and regulatory actions regarding the exhaust gas from ships are being strengthened by both international organizations and national governments, to protect human health and the environment. Exhaust gas traps are excluded from exhaust gas regulation applications, but, recently, the United States, Britain, and other developed countries have examined a variety of ways to improve the system, including the introduction of electric propulsion systems to prevent air pollution generated by naval ships. This study investigates a large number of smoke problems of naval diesel engines to verify the effect of improving the nozzle characteristics. An exhaust gas emission measurement method to determine the quality of pollutant exhaust gas generated during low-load operation is proposed through the research methodology of the smoke problem. It was confirmed that the emissions value is improved by decreasing the nozzle hole diameter and increasing the injection pressure. At the same time, the flow rate decrease equation and setting up a test memo based on the nozzle diameter confirmed that the fuel consumption, to which the nozzle diameter in the flow path is related, is reduced.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.217-222
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• 2016

This study investigates the design, analysis, and implementation of the square-root extended Kalman filter by using an algorithm derived by combining the Potter or Carlson algorithm with the modified Gram-Schmidt algorithm, for sensorless speed control of a permanent-magnet synchronous motor. The sensitivity of the Kalman filter to round-off errors is a well-known problem. A possible way to address this limitation is by combining the square-root concept and Kalman filter that can improve the numerical performance and solve instability-related problems such as divergence. This paper presents the design and analysis of the implementation of such a square-root extended Kalman filter. To demonstrate the performance of the proposed filter, experimental results under several operating conditions, such as high and low speeds, reversal rotation, detuned parameters and load test, have been analyzed. Further, code sizes and operation times have been compared. Experimental results establish the performance of the proposed square-root extended Kalman filter-based estimation technique for sensorless speed control of a permanent-magnet synchronous motor.

• Journal of Digital Convergence
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• v.12 no.8
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• pp.229-234
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• 2014

Vehicular electronic communication system has continued to develop in favor of high performance and user convenience with the evolution of auto industry. Yet, due to the nature of communication system, concerns over intruder attacks in transmission sections have been raised with a need for safe and secure communication being valued. Any successful intruder attacks on vehicular operation and control systems as well as on visual equipment could result in serious safety and privacy problems. Thus, research has focused on hardware-based security and secure communication protocols. This paper proposed a safe and secure vehicular communication protocol, used the formal verification tool, Casper/FDR to test the security of the proposed protocol against different types of intruder attacks, and verified that the proposed protocol was secure and ended without problems.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.289-296
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• 2010

The purpose of this study is to evaluate various pre-treatment methods and proprieties of water quality for wastewater reuse using reverse osmosis (RO) processes. Secondary effluents were sampled from wastewater treatment plants and lab scale pre-treatments and RO filtration test were conducted systematically. Specifically, different types of pre-treatments, such as coagulation, microfiltration and ultrafiltration, were employed to evaluate the removal efficiency of particle and organic matters which may affect the membrane fouling rate. RO process was later added to eliminate trace amounts of remaining organic matters and salt from the raw water for wastewater reclamation. The permeate through the RO process satisfied water quality regulations for industrial water uses. The experimental results showed that the initial fouling tendency differed not only by the feed water properties but also by the membrane characteristics. Membrane fouling was greater for the membranes with large surface roughness, regardless of the hydrophobicity and zeta potentials. Thus both careful consideration of pre-treatment options and proper selection of RO membrane are of paramount importance for an efficient operation of wastewater treatment.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.3
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• pp.21-32
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• 2005

In Incheon metropolitan city, the urban open space areas are deficient and it is nearly impossible to obtain newly the land for parks by reason of the risk of the land value, the budgetary deficit and so forth. Therefore, it seems to be urgent to consider how to manage the established urban natural park efficiently to enhance the quality of recreational experiences of the public. The organization for the urban natural parks management is to be completely put in good order, for the objects to manage is changeable as well as diverse and what users need should be full satisfied. The purpose of this study is to investigate the differences of urban natural park's management suggest the improvement and development directions in urban natural park by group(professionals and Users). To do this, data were collected in the typical regions by urban natural park for this study, using the questionnaires. In these urban natural park, the on-site survey was carried out the users of these urban natural park during October in 2004. Also The analysis was done with the valid questionnaires of user's 644 and professional's 146. The questionnaires contained three of categories : openspace types' satisfaction and urban natural park's satisfaction, and management, and park user's socioeconomic characteristics and behaviors. Data collected from respondents were analysized by descriptive statistics, T-test, factor analysis and regression analysis. The results of this study can be summarized as follows; The evaluation of urban natural park management is predicted the operation management. So, one can draw a conclusion that user's needs is likely to be increased correspondingly as urban natural park planning and design, management which meets the overall satisfaction. Using the results of this study, we can make a guideline for a park management program, market positioning, standards and provisions of urban natural park by group.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.10
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• pp.928-936
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• 2013

3D crosstalk is one of the disturbing things to recognize 3D images. This is caused by the phenomenon that input image for left eye is transferred at the right eye and right eye is transferred at the left eye because of the imperfect isolation by the device characteristics. In this paper, we review the 3D PDP (Plasma Display Panel) operation using active shutter glasses and crosstalk measurement method and investigate the major cause of 3D crosstalk and extend conventional 3D crosstalk using full white and full black image input to Gray-to-Gray (GtoG) 3D crosstalk. We suggest a specific method to reduce Gray-to-Gray 3D crosstalk by using Look up Table (LUT) and sub-field mapping in PDP. And then, we verify the method by measuring GtoG 3D crosstalk rate through specific test images and numerical results.

• Journal of the Korean association of regional geographers
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• v.18 no.1
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• pp.1-16
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• 2012

As the tourists of ecotourism are increasing, the supply for detailed information on tourist attraction is also significantly increasing. As a result of survey given to tourists, it showed that they are more interested in natural ecological resources rather than history or culture among resources of ecotourism and pointed out that more information on the region needs to be supplemented. In order to provide accurate, detailed and standardized information to tourists, ecotourism resources were categorized as experience type from the position of consumer and ecological resource type. And the category of experience is again divided into 4 types - nature, education, communication and adventure. Moreover, after developing the web-based homepage for it, the research proposed the cases of Tae-an area and Ulleungdo Island. If the problems from test operation are supplemented, it is expected to suggest the standard of mobile based digital storytelling technology in the field of ecotourism.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.82-88
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• 2011

Lean combustion and exhaust emission characteristics in a ethanol fueled spark-ignited engine according to ethanol-gasoline fuel blending ratio were investigated. The test engine was $1591cm^3$ and 10.5 of compression ratio SI engine with 4 cylinders. In addition, lambda sensor system was connected with universal ECU to control the lambda value which is varied from 1.0 to 1.5. The engine performance and lean combustion characteristics such as brake torque, cylinder pressure and rate of heat release were investigated according to ethanol-gasoline fuel blending ratio. Furthermore, the exhaust emissions such as carbon monoxide (CO), unburned hydrocarbon (HC), nitrogen oxides ($NO_x$) and carbon dioxide ($CO_2$) were measured by emission analyzers. The results showed that the brake torque, cylinder pressure and the stability of engine operation were increased as ethanol blending ratio is increased. Brake specific fuel consumption (BSFC) was increased in higher ethanol blending ratio while brake specific energy consumption (BSEC) was decreased in higher ethanol blending ratio. The exhaust emissions were decreased as ethanol blending ratio is increased under overall experimental conditions, however, some specific exhaust emission characteristics were mainly influenced by lambda value and ethanol-gasoline fuel blending ratio.

• Journal of Engineering Education Research
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• v.16 no.3
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• pp.3-9
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• 2013

It is very difficult for students to understand "Computer System Architecture" written by M. Morris Mano only through theoretical education. This study has developed DigCom as a computer architecture practice kit to make it easier for students to understand computer operations. The practice kit operates in the same manner as the "simple computer" described in Computer System Architecture. The purpose of this study is to examine whether using DigCom is effective in improving learning outcomes. For the purpose, t-test and two-way ANOVA were used to determine if there is any difference in learning outcomes between the experimental group of students who used DigCom and the control group who took the course in a traditional setting without using DigCom. The main conclusions of the study are as follows: Students understand computer operations better when DigCom is used in class.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.597-603
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• 2012

It is necessary to accurately evaluate the resistance performance and estimate the towing power of a tugboat for safety towing operation at actual seas. In this study, we have carried out the model tests firstly to investigate the resistance performance and flow characteristics around the tugboat in still water. The experiments are performed in infinite depth in circulation tank using 1/33.75 scaled model from 5kts to 10kts(designed speed 7kts) considering the effect of adverse and favorable current. Then the numerical calculations are executed to analyze the response amplitude operator and added resistance on tugboat due to the waves. The results obtained by the present computation are compared with the those acquired from the experiments in still water. As a result, it is noted that the added resistance become larger at head sea and higher speed conditions. We can also observe that the EHP increase 70 percent in comparison with those in still water.