• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.2
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• pp.245-256
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• 2015

This study is intended to provide navigator with specific information necessary to assist the avoidance of collision and the operation of ships to evaluate the maneuverability of dead weight tonnage 8,000 tons Oil/Chemical tanker. The actual maneuvering characteristics of ship can be adequately judged from the results of typical ship trials. Author carried out sea trials based full scale for turning test in ballast condition and full load condition, semi balanced rudder and flap rudder. The turning circle maneuvering were performed on the starboard and port sides with $35^{\circ}$ rudder angle at the normal continuous rating. The results from tests could be compared directly with the standards of maneuverability of IMO and consequently the maneuvering qualities of the ship is full satisfied with its.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.1
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• pp.61-69
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• 2015

In the beginning of the 1990's, numerous shaft bearing damages, especially in aft stern tube bearing, were reported. The main reasons of bearing damages were estimated that hull deflections have been increased by more flexible hulls and propeller dynamic loads have not been considered in shaft alignment. After that time, studies to take into account hull deflections in shaft alignment have been actively carried out, but for the latter leave much to be desired. In this study, the effects of the propeller forces on the propeller shaft bearing have been investigated by estimating thrust eccentricity as reasonable as possible although some assumptions to simulate turning of ship were introduced. Three dimensional nominal wake to estimate thrust eccentricity have been calculated by using CFD analysis and model test in the towing tank. This study presents the procedure to estimate the propeller eccentric forces and their influence on the stern tube bearing for a container carrier. As a result, it has been found that the lateral propeller forces in turning condition should be considered in shaft alignment to prevent shaft bearing damages.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.4
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• pp.199-205
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• 2013

To research and develop an azimuth thruster, the new type of open water test dynamometers to measure thrust, torque, total thrust and duct force are designed and manufactured by Samsung Ship Model Basin(SSMB). A compact servomotor to be accurately controlled is connected to precise spiral bevel gear through shafting system combined by couplings and main shafts. The dynamometers have shown excellent linearity and repeatability for all components of forces and a torque. Also, the open water tests have been successfully performed to show the performance of the system. In near future, it is expected that the device can be used for the study of scale effects and development of azimuth thrusters.

• Journal of Sensor Science and Technology
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• v.5 no.6
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• pp.43-50
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• 1996

It is very important to improve the combustion efficiency and reduce pollutant emission in order to save energy and environment. Especially, thermal NOx has been reduced through monitoring burner flame, because the thermal NOx is strongly related to flame characteristics. In this work, a flame-monitoring system was fabricated with photodiode, optical fiber, interference filter and data acquisition system, and it was applied to a lab-scale methane combustion system and a testing facility. Flame intensity and mean frequency increased with increasing turbulent intensity and fuel loading. The sensor signal from flame fluctuations differed from that without flame, which showed the availability af the flame scanner to find the presence of flame. NOx emissions increased with flame intensity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.11
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• pp.1104-1111
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• 2008

The supersonic advanced trainer based on digital flight-by-wire flight control system uses aircraft flight information such as altitude, calibrated airspeed and angle of attack to calculate flight control law, and this information is measured by IMFP(Integrated Multi-Function Probe) equipment. The information has triplex structure using three IMFP sensors. Final value of informations is selected by mid-value selection logic to have more flight data reliability. As the result of supersonic flight test, pitch oscillation is occurred due to IMFP noise when altitude hold autopilot mode is engaged. This tendency may affect stability and handling quality of an aircraft during autopilot mode. This paper addresses autopilot control law design to remove pitch oscillation and these control laws are verified by non-real time simulation and flight test. Also, pitch response characteristics of pitch attitude hold autopilot mode is improved by upgrading the control law structure and feedback gain tuning during bank turn.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.127-132
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• 2009

This study presents the test results on the compaction characteristics of warm mix asphalt mixtures that include the additive in 3 different mixtures(hot mix asphalt, SBS and SMA). The tests were conducted to find out the compaction characteristics on the compactability with varying compaction time, different amount of the warm mix additive and lowering the compaction temperature. The Superpave gyratory compactor was used to find out the variation of the density when the number of the gyration is varied. A dense mixture and 3 different warm mix additives were employed to find the relationship between compactability and compaction time. The comparison of the compactability with lowering the temperature was conducted using dense mixture, SBS polymer modified mixture and stone matrix asphalt mixture(SMA). The difference of the density of warm mix asphalt mixtures was not found due to the lowering of compaction temperature when it was compared with the standard mixture and the warm mix showed the stable condition in density. In the mean time, depending upon the different warm mix additive and mixture, the difference of density and the variation trend of compaction is found to be existed and shows the relationship between these two variables.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.21-26
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• 2022

Zinc is emerging as a environment-friendly plating material to replace cadmium, which is harmful to the human body, to prevent hydrogen gas penetration or release from metal materials. Electroplating of Zn and Zn alloys, which is usually performed in an aqueous acidic atmosphere, has disadvantages such as low coulombic efficiency, corrosion, and hydrogen release, resulting in industrial use difficult. In this study, a deep-eutectic solvent was synthesized using choline chloride and ethylene glycol. Using this as a solvent, an electrolyte for Zn plating was prepared, and then zinc was plated on the STS 304 substrate. The surface microstructure and roughness were observed using SEM and AFM. The crystal structure of the electro-plated film was analyzed using XRD. Finally, the preventing effects of hydrogen release through Zn-based deep-eutectic plating on the STS 304 substrate were compared with the uncoated substrate.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.51-58
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• 2008

Development of a new design guide which is based on empirical-mechanistic concept for pavement design is in action. It is called AASHTO 2002 Design Guide in USA and the KPRP(Korean Pavement Research Project) in Korea. The material characteristic of hot mix asphalt is a key role in the design guide. Therefore it is urgent to get a proper materials database, especially the dynamic modulus of hot mix asphalt. In this research, dynamic modulus test, which is based on aged asphalt binder, has been carried out and proposed the predicted equation of dynamic modulus. Nine different hot mix asphalt with three different asphalt binder have been used for the dynamic modulus test. Short-term aging, which is covers the time for the production of asphalt plant, transportation, lay-down, and compaction, can be simulated at $135^{\circ}C$ with 2 hour curing. Long-term aging has been carried out for a performance period of asphalt pavement. The dynamic modulus of asphalt pavement increases with aging time. As the nominal aggregate size increases, the change of dynamic modulus is not big.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.313-322
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• 2011

On September 2007, numerous slopes at Jeonranam-Do collapsed as a result of rainfall related to Typhoon Nari. Failure occurred at a road cut-slope on the ${\bigcirc}{\bigcirc}$ detour road, damaging transport infrastructure. This study aims to determine the cause of failure based on field investigations, the geotechnical properties of soil, clay mineral composition, and quantitative analysis. The studied cut slope consists of weathered soil that originated from volcanic rocks, and minor faults and a mafic dyke. Surface water tends to seep into the soil because the roadway is not sealed and because of poorly installed drainage. Sieve and XRD analyses indicate that soils in the failure zone are ML and CH, which are prone to swelling due to the presence of clay minerals such as smectite and vermiculite. The slope failed due to the improper construction of drainage facilities, the presence of geological weak zones, and high soil contents of swelling clay.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.49-55
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• 2009

Our domestic economy has been developed very rapidly after 1960's. Also, it is dramatically increasing traffic on road and surround environmental issues. Especially, rapid economic growth has been induced large construction of pavement, and bigger and higher traffic for transportation. These are making air pollution, traffic noise and vibration. The social requirement against the revealed road environment and traffic sound reduction is being demanded. Traffic noise of city zone is showed over the environmental specification more than 57%. In order to overcome these situations, the social attention is being increased. The quiet pavement is the same format of permeable pavement, but is not same for functional performance. In this research, it has been carried out to evaluate the fundamental-mechanical properties of hot mix asphalt for quiet pavement. Especially, couple of laboratory tests are conducted like marshall stability, resilient modulus, indirect tensile test, and compaction energy analysis with gyratory compaction curve. Also, two-layer pavement system has been adopted for developing of quiet pavement. The basic performance of hot mix asphalt of quiet pavement show a satisfaction of specification of hot mix asphalt.