• Fire Science and Engineering
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• v.28 no.5
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• pp.44-51
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• 2014

In this study, the Mock-up office space experiments have been performed for the fire behavior analysis of the compartmented space used for the performance-based fire safety design of buildings. Mock-up test was conducted using the compartmented office space dimensions, which are 2.4 m wide, 3.6 m wide, and 2.4 m hight. Test was conducted with the combustible materials such as a desk, a chair, a computer ect. The fire load in the Mock-up office space was $18.74kg/m^2$. As a result, the temperature of the central compartment space to reach $600^{\circ}C$ were 394 to 408 s. The temperature of the corner near the entrance edge to reach $600^{\circ}C$ were 404 to 420 s. At this study, the temperature curve in the compartmented space has been predicted using the temperature data appling the BFD curve. The BFD curve factor based on the fire tests was determined by the maximum temperature of $900^{\circ}C$, 7 min to reach the maximum temperature, and the shape coefficient of 1.5. The initiating fire was rapidly increased to 9 min, and decreased.

• Journal of Navigation and Port Research
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• v.41 no.6
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• pp.381-388
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• 2017

Recently, renewed attention for technological applications within the maritime industry has taken place, particularly regarding unmanned vessels. There has been a lot of interest about the number of projects aiming at testing the operational feasibility of unmanned vessels, particularly in relation to technological, safety and security issues. Nevertheless, no studies have investigated this issue from the point of view of seafarers towards unmanned vessels; this paper aims at filling this gap. Data has been collected through a survey questionnaire. A Pearson correlational coefficient has been used to test the correlation between some of the variables. The results show that more than half of the respondents indicated that unmanned vessels do not contribute to an increase in accidents at sea. In addition, seafarers believe unmanned vessels will not be operational in the near future, with most of the respondents indicating a 10-20 year time frame. Thirdly, most of the respondents(both officers and ratings).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.9
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• pp.801-811
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• 2021

Lightning can deliver large amounts of energy to the aircraft in a short period of time, resulting in catastrophic consequence. In particular, lightning strikes accompanied by high temperature heat and current can damage aircraft surface and internal electronic equipment, seriously affecting flight safety. Lightning experiments to analyze this effect use a Component A waveform with a maximum current of 200 kA as specified in SAE ARP 5412B. However, the actual lightning occurs mostly below 35kA and lightning indirect tests are conducted by reducing waveforms to prevent damage to internal electronic equipment. In this study, we examine previous methods to plot the Component A reduced waveform and identify their limitations. We then propose a new method to plot the reduced waveform based on adjusting the correction factor of the aircraft lightning Component A waveform. Finally, the electromagnetic analysis software EMA3D was used to compare the internal induced current size reduction ratio of the internal cable harness of the EC-155B helicopter.

• Tribology and Lubricants
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• v.38 no.3
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• pp.73-83
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• 2022

This paper is concerned with an analysis of a surface edge crack emanated from a sharp contact edge. For a geometrical model, a square wedge is in contact with a half plane whose materials are identical, and a surface perpendicular crack initiated from the contact edge exists in the half plane. To analyze this crack problem, it is necessary to evaluate the stress field on the crack line which are induced by the contact tractions and pseudo-dislocations that simulate the crack, using the Bueckner principle. In this Part I, the stress filed in the half plane due to the contact is re-summarized using an asymptotic analysis method, which has been published before by the author. Further focus is given to the stress field in the half plane due to a pseudo-edge dislocation, which will provide a stress solution due to a crack (i.e. a continuous distribution of edge dislocations) later, using the Burgers vector. Essential result of the present work is the corrective functions which modify the stress field of an infinite domain to apply for the present one which has free surfaces, and thus the infiniteness is no longer preserved. Numerical methods and coordinate normalization are used, which was developed for an edge crack problem, using the Gauss-Jacobi integration formula. The convergence of the corrective functions are investigated here. Features of the corrective functions and their application to a crack problem will be given in Part II.

• Journal of the Korean Geotechnical Society
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• v.26 no.4
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• pp.47-58
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• 2010

Seepage rate through the core zone of rockfill dam, estimated from graphical technique and the equation by Sakamoto (1998), is different from the real condition because of neglecting unsaturated flow. With existing method to estimate total seepage rate, it is difficult to understand the tendency of total seepage rate changes by reservoir water level change. Steady state seepage rate and the factors affecting the time needed to attain to changes of reservoir water level and saturated hydraulic conductivity and unsaturated hydraulic properties of core material are analysed thorough the 2-D steady and unsteady state seepage analyses of Soyanggang dam. Numerical results revealed that the seepage rate can be expressed by the linear equation form and the value of unsaturated soil parameter n is the most important factor affecting the seepage rate and the time needed to attain steady state. The estimation method presented in this study can be used by the designer and the personnel of dam safety for convenient estimation of seepage rate and quantitative analysis of measured seepage rate without 2-D and 3-D numerical analyses.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.358-371
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• 2014

For the systematic scientific management in Cheonsu Bay of Korea, this study was conducedt to survey the particle composition, organic matter(I.L.) and heavy metals in farming and non-farming areas. The sediment of study area showed feature mixed property by sand, silt and clay. The farming area showed superior by fine-grained sediment, non-farming area showed superior by coarse-grained sediment. The organic pollution of farming area were appeared to be heavily polluted more than non-farming area. The concentration of total nitorgen in sediment was higher farming area than non-farming area. Also, in the case of heavy metals pollution in sediments, farming area was higher than non-farming area. The correlation analysis among to heavy metals, organic matter and particle size was found to have a good interrelationship. For evaluation of heavy metals pollution of sediments, three criteria are applied, Enrichment Factor(EF), Geoaccumulation index(Igeo) and NOAA criteria for sediment. In the case of EF, Heavy metals pollution was appeared to artificial effect all heavy metals if except Cu. In the case of Geoaccumulation index, Cu, Al, Pb was shown zero grade, that is non polluted group, and Cd, Hg, Cr was shown to 0~1 grade, that is mid polluted group, As was shown to 2 grade, that is moderately polluted group. In the case of NOAA, pollution levels of heavy metals except Cd belonged to a group of ERL(Effect range low)~ERM(Effect range median).

• Journal of Food Hygiene and Safety
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• v.20 no.1
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• pp.22-35
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• 2005

A survey was conducted to investigate the perception of food sanitation officers toward the Genetically Modified Foods. They were mainly from Regional Agencies of KFDA, City/Province office, and National quarantine station. Some of them were professors of university and researchers of research institute. Most of respondents had experiences of hearing or reading GM foods (over $95\%$) and over $90\%$ of respondents much needed the label of GM foods. Although some of officers of city/province office and national quarantine station showed less knowledge than other respondent groups, most of respondents had basic knowledge about biology. The frequency of respondents worked over 20 years and worked in the general administration was higher than that of other groups in the question of unsafe of GM foods. The answer frequency of careless treatment of foods was highest in the question of risk factor, and the frequency of GM foods was lowest ($4.4\%$). It was concluded that food sanitation officers had positive opinion about GM foods, but there were some differences in the knowledge among agencies. Therefore, it is necessary more educations and informations are needed for food sanitation officers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.141-154
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• 2015

In general, conventional criticality analysis for spent fuel transport/storage systems have been performed based on the assumption of fresh fuel concerning the potential uncertainties from number density calculations of actinide nuclides and fission products in spent fuel. However, these evaluation methods cause financial losses due to an excessive criticality margin. In order to overcome this disadvantage, many studies have recently been conducted to design and commercialize a transportation and storage cask applied to the Burnup Credit (BUC). This study conducted an assessment to ensure criticality safety for reactor operating parameters, axial burn-up profiles and misload accident conditions, which are the factors that are likely to affect criticality safety when the BUC is applied to the dual-purpose cask under development at the KOrea RADioactive waste agency (KORAD). As a result, it was found that criticality resulting from specific power, changed substantially and relied on conditions of low enrichment and high burn-up. Considering the end effect in the case of high burn-up produced a positive-definite result. In particular, the increment of maximum effective multiplication factors due to misloading was 0.18467, confirming that misload is a factor that must be taken into account when applying the BUC. The results of this study may therefore be utilized as references in developing technologies to apply the BUC to domestic models and operational procedures or preventing any misload accidents during the process of spent fuel loading.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.103-113
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• 2020

Jack-up drilling rigs are widely used in the offshore oil and gas exploration industry. Although originally designed for use in shallow waters, trends in the energy industry have led to a growing demand for their use in deep sea and harsh environmental conditions. To extend the operating range of jack-up units, their design must be based on reliable analysis while eliminating excessive conservatism. In current industrial practice, jack-up drilling rigs are designed using the working(or allowable) stress design (WSD) method. Recently, classifications have been developed for specific regulations based on the load and resistance factor design (LRFD) method, which emphasises the reliability of the methods. This statistical method utilises the concept of limit state design and uses factored loads and resistance factors to account for uncertainly in the loads and computed strength of the leg components in a jack-up drilling rig. The key differences between the LRFD method and the WSD method must be identified to enable appropriate use of the LRFD method for designing jack-up rigs. Therefore, the aim of this study is to compare and quantitatively investigate the differences between actual jack-up lattice leg structures, which are designed by the WSD and LRFD methods, and subject to different environmental load-to-dead-load ratios, thereby delineating the load-to-capacity ratios of rigs designed using theses methods under these different enviromental conditions. The comparative results are significantly advantageous in the leg design of jack-up rigs, and determine that the jack-up rigs designed using the WSD and LRFD methods with UC values differ by approximately 31 % with respect to the API-RP code basis. It can be observed that the LRFD design method is more advantageous to structure optimization compared to the WSD method.

• The Korean Journal of Pesticide Science
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• v.16 no.1
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• pp.35-42
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• 2012

This study was carried out to elucidate the residual characteristics and calculate processing factors of difenoconazole in ginseng and its processed products, such as dried ginseng, red ginseng and their water and alcohol extracts. The pesticide was sprayed onto the ginseng according to its pre-harvest intervals in 2009 (four-year-old ginseng) and 2010 (five-year-old ginseng). Harvested ginseng was processed to dried ginseng, red ginseng and their extracts according to the commercially well-qualified conventional methods provided by the Korea Ginseng Corporation. Limit of detection (LOD) and limit of quantitation (LOQ) of difenoconazole in fresh ginseng were 0.001 and 0.003 mg/kg, respectively. In case of processed ginseng products, their levels were 0.002 and 0.007 mg/kg, respectively. Concentration of difenoconazole in both fresh ginseng and its processed products increased with the experimental period. Processing factors, calculated as a ratio of difenoconazole concentration in processed products to fresh ginseng were found to be 1.71 to 2.17 and 1.62 to 2.03 in case of dried and red ginseng, respectively, while those for their extracts ranged from 1.76 to 2.98. In case of five-year-old dried ginseng and red ginseng as well as their extracts, the ranges of processing factor of difenoconazole were found to be 2.9 to 3.1, 1.9 to 2.2 and 2.4 to 4.7, respectively.