• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.2 s.29
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• pp.133-140
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• 2007

Since early times, captain have been sailing to select the optimum route considering the weather, ship loading status condition and operational scheduling empirically. However, it is rare to find digitalized onboard route support system whereas weather facsimile or wave and swell chart are utilized for the officer, based on captain's experience. In this paper, optimal route safety assessment system which is composed of voyage efficiency and safety component is introduced. Optimum route minimizea ETA(estimated time of arrival) and fuel consumption that shipping company and captain are requiring to evaluate for efficient voyage considering speed loss and power increase based on wave added resistance of ship. In the view point of safety, seakeeping prediction is performed based on 3 dimensional panel method. Finally, It is assistance measure for ship's optimum navigation route safety planning & assessment.

• Journal of Conservation Science
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• v.25 no.4
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• pp.373-381
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• 2009

To preserve steel cultural properties on display outdoors, the surface of these relics is processed with a covering treatment, which is a typical anti-corrosion method. Since the registered cultural heritage of Korea No. 78 Locomotive at Jangdan Station of Gyeongui Line will be treated by preservation process and displayed in the open outdoor area, effective surface covering agents were selected through testing to prevent the corrosion of the locomotive. The mixed wax are based on two types of microcrystalline wax which is one of regular surface covering agents for locomotives and bee‘s wax. For the weather resistance test, 3 types of wax were applied to each specimen of the locomotive and the specimens were tested in the Xenon-Arc Accelerated Weathering Tester for 1000 hours in accordance with the ISO 4892-1981 criteria and the test results were compared. As a result, on the surface of the specimen coated with the bee's wax, a whitening event appears after 400 hours which causes aging, and the specimens coated by the microcrystalline wax showed signs of a whitening event after 800 hours. The moisture contact angle with the microcrystalline wax coating was also less than with the bee's wax. Therefore, it was found that the high temperature microcrystalline wax is the most effective coating agent in terms of weather resistance and moisture blocking capability and the high temperature microcrystalline wax was adopted for coating the surface of the locomotive.

• Journal of Conservation Science
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• v.35 no.5
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• pp.480-493
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• 2019

In this study, the method for processing glue and glue-alum sizing from the dancheong ground treatment was evaluated with respect to weather resistance, and its effect on the conservation of dancheong was analyzed. Viscosity and pH of the glue and glue-alum specimen were measured and classified into three categories(none layer, glue layer, and glue-alum layer), which were further classified according to low concentration(four times for 2%) and high concentration(once for 10%). The base layer formation was subsequently classified into three categories based on pigment adoption, namely, Noerok(celadonite), Seokganju(terra rossa), and Jangdan(red lead). The completed specimen was subjected to a changing-environment experiment for evaluating weather resistance and observing the surface. Color variations were analyzed before and after the experiment. The results indicate that glue-alum sizing comprising 5% alum or 7% alum has strong acidity that can affect the life of dancheong, and the high level of 7% alum makes it difficult to create a solid coating layer. After ultraviolet irradiation, the specimen with 7% alum changes its color to yellow. Furthermore, after moisture absorption and drying, cracks can be observed on the entire specimen surface that corroborate the physical change. Additionally, gas-based corrosion causes marginal surface changes. Hence, the formation of a stable coating layer can be achieved by incorporating a low concentration glue solution that is almost neutral, and the application of glue-alum sizing having 2% concentration can aid in the conservation of dancheong.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.294-303
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• 2020

This study discusses data collection, calculation of wind and wave-induced resistance, and speed-power analysis of an 8,600 TEU container ship. Data acquisition system of the ship operator was improved to obtain the data necessary for the analysis, which was accomplished using SPA (Ship Performance Analysis, Park et al., 2019) in conformation with ISO15016:2015. From a previous operation profile of the container, the standard operating conditions of mean draft were 12.5 m and 13.6 m, which were defined with the mean stowage configuration of each condition. Model tests, including the load-variation test, were conducted to validate new ship performance and for the speed-power analysis. The major part of the added resistance of container ship is due to the wind. To check the reliability of wind-resistance calculation results, the resistance coefficients, added resistance, and speed-power analysis results using the Fujiwara regression formula (ISO15016:2015) and Computational fluid dynamics (Ryu et al., 2016; Jeon et al., 2017) analysis were compared. Wind speed and direction measured using an anemometer were used for wind-resistance calculation and the wave resistance was calculated using the wave-height and direction-data from weather information. Also, measured water temperature was used to calculate the increase in resistance owing to the deviation in water density. As a result, the SPA analysis using measured data and weather information was proved to be valid and able to identify the ship's resistance propulsion performance. Even with little difference in the air-resistance coefficient value, both methods provide sufficient accuracy for speed-power analysis. The differences were unnoticeable when the speed-power analysis results using each method were compared. Also, speed-power analysis results of the 8,600 TEU container ship in two draft conditions show acceptable trends when compared with the model test results and are also able to show power increase owing to hull fouling and aging. Thus, results of speed-power analysis of the existing 8,600 TEU container ship using the SPA program appropriately exhibit the characteristics of speed-power performance in deal conditions.

• International Journal of Highway Engineering
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• v.14 no.4
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• pp.1-8
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• 2012

PURPOSES : Skid resistance on pavements plays an important role in reducing the risk of vehicle skidding on wet surface particularly. Almost 9.3 percent of traffic accidents were occurred under rainy condition and these are over-represented in terms of the severity of the crashes. Recently, unusual weather conditions referred widely as the intensified rainfalls justify the need of a systematic management of skid resistance. In this context, the study carried out the observational study on the skid resistance characteristics of different types of pavement with the time passage. METHODS : This study measured the skid resistance with Pavement Friction Tester at three times within five years. The skid resistance measurement has followed the method suggested by ASTM. RESULTS : As the main results under the scope of this study, skid resistance of asphalt concrete has not nearly reduced with time. On the contrary, skid resistance of cement concrete has been rapidly reduced with time though the highest resistance was gained at the early observation. Porous asphalt concrete shows a steady decrease of skid resistance with time, anyway, the reduction rate according to the increase of measurement speeds is relatively lower than the others. CONCLUSIONS : Based on our study, skid resistance of the pavement should be regarded as one of the pavement management system, so periodic measurement should be made to assure road safety as a whole.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.645-650
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• 2003

The purpose of this study is to provide the optimum mix design of cold weather concrete to be placed at the foundation structures in substation. The basic performance tests including slump and slump flow, air content, compressive strength and freezing & thawing resistance were conducted for cold weather concrete by varying with W/C ratios such as 40%, 50% and 60% and air contents such as 3%, 4%, 5% and 6%. The effect on durability of concrete corresponding to the increasing amount of air content and W/C ratio was evaluated and the optimum mix design was recommended. From this study, the concrete mix design containing 6% of air content and 45% of W/C ratio is recommended for the foundation concrete of substation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.04a
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• pp.90-100
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• 1998

There is a limitation for a ship which is sailing on sea to gather weather and seastate informations. To make up for this weakness , land organizations can gather wider variety of information and evaluate the seakeeping performance on ship. and supply this information to the ship. In this study, calculated the response amplitude of ship motions with the weather information provided in real time, the norminal speed loss with obtaining increased of resistance caused by wave and stochastic process of the seakeeping performance elements. And the results have been achieved to develop a system whichcan evaluate the synthetic seakeeping performance. Using this system , the results have been studied to determine the feasibility of using this simulation inactual operation onboard ship.

• Journal of the Korean Institute of Navigation
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• v.22 no.2
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• pp.23-32
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• 1998

There is a limitation for a ship which is sailing on sea to gather weather and seastate informations. To make up for this weakness, land organizations can gather wider variety of information and evaluate the seakeeping performanceon ship. And supply this information to the ship. In this study, calculated the response amplitude of shp motions with the weather information provided in real time, the nominal speed loss with obtaining increase of resistance caused by wave and stochastic process of the seakeeping performance elements. And the results have been achieved to develop a system which can evaluate the synthetic seakeeping performance. Using this system, the results have been studied to determine the feasibility of using simulation in actural operation onboard ship.

• Journal of the Korea Institute of Building Construction
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• v.2 no.2
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• pp.151-156
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• 2002

When fresh concrete is exposed to low temperature, the concrete may suffer frost damage due to freezing at early ages and strength development may be delayed. One of the solution methods for resolve these problems is to reduce freezing temperature of concrete by the use of chemical admixture called Accelerators for freezing resistance. In this study, we investigate the effect on strength development of cement mortar using accelerators for freezing resistance with the variance curing condition. As the result of this study, the mortar using accelerators for freezing resistance show that continuously strength development in curing condition of -5$^{\circ}C$. And compressive strength under the variance temperature condition was higher than constant temperature condition in same maturity.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.155-158
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• 2008

In this study we compared corrosion resistance tests which were carried out according to the national technique standard and the UL standard to ensure the reliability of smoke detectors in foul weather. The sensitivity of smoke detectors became so blunt that the least operational smoke concentration was a maximum change of 13% in the national technique standard, while it was a maximum change of 145% in the UL standard. As a result of this study the test method of corrosion resistance was made an objective evaluation in the national technique standard. Therefore it could be said that a basis of developing the test method of corrosion resistance was prepared for our country.