• Membrane Journal
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• v.11 no.3
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• pp.124-132
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• 2001

Silica membranes were prepared on a porous ${\alpha}$-alumina tube with pore size of 150nm by sol-gel and chemical vapor deposition(CVD) method for hydrogen separation at high temperatures. Silica and ${\gamma}$-lumina membranes formed by the sol-gel method possessed a large amount of mesopores of a Knudsen diffusion regime. In order to improve the $H_2$ selectivity, silica was deposited in the sol-gel derived silica/${\gamma}$-alumina layer by thermal decomposition of tetraethyl orthosilicate(TEOS) at $600^{\circ}C$. The CVD with forced cross flow through the porous wall of the support was very effective in plugging mesopores that were left unplugged in the membranes. The CVD modified silica/alumina composite membrane completely rejected nitrogen permeation and thus showed a high $H_2$ selectivity by molecular sieve effect. the permeation of hydrogen was explained by activated diffusion and the activation energy was 9.52kJ/mol.

• Journal of Navigation and Port Research
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• v.44 no.3
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• pp.151-157
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• 2020

Harmful aquatic organisms introduced by ship movement cause marine ecosystem disturbances and are in the form of ballastwater and biofouling. Harmful marine life from ballastwater has been considerably reduced because mandatory treatment on all vessels is required to install onboard vessels. However, there remains risk of migration because biofouling is recommended to countries for management through the IMO guidelines. In particular, biofouling management has recently attracted attention for achieving IMO GHG reduction targets because it contributes to energy efficiency, as well as there are reasons for marine ecosystem protection. In recent years, increasing international consensus on the need for biofouling management is likely to lead to enforcement regulations. Thus, this study suggests the management method of hull attachment organisms in Korea, focusing on the cases of foreign countries that have regulated hull attachment organisms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1192-1200
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• 2007

A general rainfall outflow in urban drainage has early time of concentration because urban drainage areas are most paved area. In general, rainfall outflow is flowed in drainage pump station and is discharged to rivers in urban areas. However it is excluded through drainage pumps about a heavy rainfall which exceed the design rainfall and the rainfall outflows increase the urban inundation risk. A current pump operation is control according to water level of collecting well or reservoir in drain pump station. But recently, the localized downpours are happened frequently in urban drainage and the current pump stations are frequently incapable of the heavy rainfall outflows. In this study, a real urban inundation was simulated and the drain capacity of drain pump station was evaluated by analysis about flood-factor in urban underground passage. Then the analysis about the inundation was done by the simulation about the real rainfall which cause the inundation. Also, in the simulation the inundation risk and the evaluation of flood-factor were analyzed according to change of the pump operation rule.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.3
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• pp.245-256
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• 1999

Watershed delineation is the process of tracing surface water flow across a landscape to identify hydrologic basins. Manual and automated techniques have been developed to trace surface waters and locate watersheds on a variety of landscape. Low topographic relief landscapes, however, are particulary problematic for automated watershed delineation techniques. Therefore, this study aims at focusing the watershed delineation algorithm of low topographic relief landscape. By using topogrid, which manages enforcement drainage algorithms and incorporates topographic data into stream data, this study delineates watershed boundary in low relief landscape. Based on this research, in a low topographic relief landscape, enforcement drainage algorithms using topogrid generate better source grid to delineate watershed boundary than using only TIN. Also, comparing automated watershed delineation which incorporates contours and elevations into stream data with manual watershed delineation, we can know that the incorporation of both elevation and stream data generate more effective results.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.157-166
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• 1994

Recently. the excessive diesel engine torsional excitation of typical energy saving ships has resulted in severe damages of the propeller shaft. Up to now the design and torsional vibration analysis of the marine diesel shafting system has been performed on the assumption that excitations are deterministic. But a diesel engine excitation varies randomly from cylinder to cylinder and from cycle to cycle, due to the imperfect operation of the engine components due to engine misfiring. consequently, a more rational analysis method for the propulsion shafting torsional vibration is required. In this paper probabilistic analysis method of the marine diesel engine shafting system under torsional vibration is presented. First a response surface representing maximum shear stresses in a shafting system is built. Then Monte Carlo simulation with subsequent approximation of the results by one of Pearson's curves, is performed. Some numerical results based on the proposed method are compared with t도 some numerical data available. They show acceptable agreements with the data.

• The Journal of the Acoustical Society of Korea
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• v.41 no.1
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• pp.70-75
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• 2022

The critical bandwidth represents response interactions with respect to a signal tone and their neighboring bands. This study was to analyze the critical bandwidths of a clinically important 500 Hz tone in Korean young male and female subjects (male = 10, female = 10) at a conversational level (60 dB HL). Data were measured with notched band noise and two alternative forced choice methods. Results showed that the critical bandwidth was slightly greater (95 Hz) than the previous Western measures. There were no statistically significant differences in gender, nor were there any significant differences in lateralization of the ear (p > 0.05). These results may have implications in optimizing effective tinnitus masking or the related clinical applications.

• Nuclear Engineering and Technology
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• v.26 no.4
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• pp.516-525
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• 1994

Since the TMI and Chernobyl accidents, many passive safety features are suggested in advanced reactors in order to enhance the safety in future nuclear power plants. In order to verify the effectiveness and provide the data for detailed design of passive cooling system, in the present work, the effects of air inlet position and external condition on the natural circulated air flow rate and the natural and forced convective heat transfer coefficient have been investigated for the one-side heated closed path such as the passive containment cooling system of the Westinghouse's AP-600. A series of experiments have been peformed with the 1/26th scaled segment type test facility of the AP-600 passive containment. Under natural and forced convection, the air velocities and temperatures are measured at several points of the air flow path. The experimental result are compared with a simple one-dimensional model and it shows a good agreement.

• The Korean Journal of Air & Space Law and Policy
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• v.19 no.1
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• pp.9-35
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• 2004

A launching State shall be absolutely liable to pay compensation for damage caused by its space object on the surface of the earth or to aircraft in flight. The compensation which the launching State shall be liable to pay for damage under "the Convention on International Liability for Damage caused by Space Objects" shall be determined in accordance with international law and the principles of justice and equity, in order to provide such reparation in respect of the damage as will restore the person, natural or juridical, State or international organisation on whose behalf the claim is presented to the condition which would have existed if the damage had not occurred. In the event of damage being caused elsewhere than on the surface of the earth to a space object of one launching State or to persons or property on board such a space object by a space object of another launching State, and of damage thereby being caused to a third State or to its natural or juridical persons, the first two States shall be jointly and severally liable to the third State, to the extent indicated by the following: If the damage has been caused to the third State on the surface of the earth or to aircraft in flight, their liability to the third State shall be absolute; If the damage has been caused to a space object of the third State or to persons or property on board that space object elsewhere than on the surface of the earth, their liability to the third State shall be based on the fault of either of the first two States or on the fault of persons for whom either is responsible. The Insurance requirements are satisfied for a launch or return authorised by a launch permit if the holder of the permit or authorisation is insured against any liability that the holder might incur to pay compensation for any damage to third parties that the launch or return causes; and the Commonwealth is insured against any liability that Commonwealth might incur, under the Liability Convention or otherwise under international law, to pay compensation for such damage. The liability for Damage caused by Space Objects should be regulated in detail in Korea.

• The Korean Journal of Air & Space Law and Policy
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• v.33 no.2
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• pp.169-197
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• 2018

The purpose of this study is to present a reasonable and concrete standard for the Korean aviation insurance compulsory subscription system. Through this, we aim to improve the current revision of laws and regulations, and ultimately create an environment in which the safety and property of the Korean people who use aircraft with appropriate aviation insurance can be secured. In particular, by reviewing the aviation business law and its new laws and regulations enacted in 2017, the legislative improvement direction of aviation insurance will be proposed. In order to maintain the continuous growth of the air transportation industry and to make amicable compensation for the victims, considering the characteristics of the total accident, instantness, and giganticness of air accidents in which a lot of people and property are lost in the event of an accident, adequate insurance coverage is essential. In this respect, the compulsory insurance to amend the principle of freedom of contract, which is the great principle of the modern judicial system, will be persuasive. However, in comparison with foreign legislation, the legal provisions on Korea's obligation to comply with aviation insurance need to be revised around the following issues: First, it is reasonable to enforce the regulation of the mandatory aviation insurance by legislation from the Congress not by administrative regulations. Because it will force the monetary obligations of the individual such as common air carriers. Second, our law regulations respond to various kinds of air damages by using the phrase "limit of liability stipulated in international conventions". However, as we have seen in the text, the range of compensation are various according to the use of legal instruments in international conventions such as the Montreal Convention, which governs the compensation of passengers for damages to passengers today. Third, in countries with narrow territories, such as Korea, there are big differences in flying time and insurable risk between domestic and international transportation. Therefore, it is necessary to divide domestic transportation and international transportation even in the obligation to join the insurance. This dual discipline has the advantage for rookies in air carrier market who mainly start their business from domestic service. Fourth, according to Korean law, the regulations of automobile loss insurance is applicable to the aviation mandatory insurance of unmanned aerial vehicle accident which is lack of persuasion. In the future, it will be appropriate to discipline insurance for unmanned aerial vehicles with unlimited potential for development from a long-term perspective.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.150-160
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• 2004

This study investigates the influential factors for the user's satisfaction in usage of PDA in Korea Postal Services. This is the case of user's acceptance of information technology that organization mandatorily implements for the sake of employee's productivity. The factors examined in this study include system quality, information quality, perceived usefulness, user satisfaction, and compatibility with work. All these factors were found significant for users satisfaction. Especially, we notice the close relationship between compatibility with work, perceived usefulness, and user satisfaction in case of nonvolitional IT usage.