• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.175-183
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• 2022

The collision between a ship and bridge across a waterway may result in extremely serious consequences that may endanger the safety of life and property. Therefore, factors affecting ship bridge collision must be investigated, and the impact force should be discussed based on various collision conditions. In this study, a finite element model of ship bridge collision is established, and the peak impact force of a ship bridge collision based on 50 operating conditions combined with three input parameters, i.e., ship loading condition, ship speed, and ship bridge collision angle, is calculated via numerical simulation. Using neural network models trained with the numerical simulation results, the prediction model of the peak impact force of ship bridge collision involving an extremely short calculation time on the order of milliseconds is established. The neural network models used in this study are the basic backpropagation neural network model and Elman neural network model, which can manage temporal information. The accuracy of the neural network models is verified using 10 test samples based on the operating conditions. Results of a verification test show that the Elman neural network model performs better than the backpropagation neural network model, with a mean relative error of 4.566% and relative errors of less than 5% in 8 among 10 test cases. The trained neural network can yield a reliable ship bridge collision force instantaneously only when the required parameters are specified and a nonlinear finite element solution process is not required. The proposed model can be used to predict whether a catastrophic collision will occur during ship navigation, and thus hence the safety of crew operating the ship.

• Journal of Integrative Natural Science
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• v.4 no.2
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• pp.149-157
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• 2011

Urbanization of the world's population has given rise to more than 450 cities around the world with populations in excess of 1 million (megacity) and more than 25 so-called metacities with populations over 10 million (Brinkhoff, 2010). The United States today has a total resident population of more than 308,500,000 people, with 81 percent residing in cities and suburbs as of mid - 2005 (UN, 2008). Urban meteorology is the study of the physics, dynamics, and chemistry of the interactions of Earth's atmosphere and the urban built environment, and the provision of meteorological services to the populations and institutions of metropolitan areas. While the details of such services are dependent on the location and the synoptic climatology of each city, there are common themes, such as enhancing quality of life and responding to emergencies. Experience elsewhere (e.g., Shanghai, Helsinki, Tokyo, Seoul, etc.) shows urban meteorological support is a key part of an integrated or multi-hazard warning system that considers the full range of environmental challenges and provides a unified response from municipal leaders. Urban meteorology has come to require much more than observing and forecasting the weather of our cities and metropolitan areas. Forecast improvement as a function of more and better observations of various kinds and as a function of model resolution, larger ensembles, predicted probability distributions; Responses of emergency managers, government officials, and users to improved and probabilistic forecasts; Benefits of improved forecasts in reduction of loss of life, property damage, and other adverse effects. A national initiative to enhance urban meteorological services is a high-priority need for a wide variety of stakeholders, including the general, commerce and industry, and all levels of government. Some of the activities of such an initiative include: conducting basic research and development; prototyping and other activities to enable very--short and short range predictions; supporting and improving productivity and efficiency in commercial and industrial sectors; and urban planning for long term sustainability. In addition urban test-beds are an effective means for developing, testing, and fostering the necessary basic and applied meteorological and socioeconomic research, and transitioning research findings to operations. An extended, multi-year period of continuous effort, punctuated with intensive observing and forecasting periods, is envisioned.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.423-430
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• 2013

An algorithm to allow shoreline movement during numerical experiment on sediment transport, deposition or resuspension for general coastal morphology is proposed here. The bed slope near shoreline, i.e. mean sea level, is influenced by bed material, tidal current, waves, and wave-induced current, but has been reported to remain within a stable range. Its annual variation is not large, either. The algorithm is adjusting the bathymetry, if the largest bed slope within shoreline band exceeds a given bed slope due to continuous erosion at zones below the shoreline. This algorithm automatically describes retreat of shoreline caused by erosion, when used within a numerical system. The algorithm was tested to a situation which includes a continuous dredging at a point, and showed satisfactory development of concentric circle contours. Next, the algorithm was tested to another situation which includes sinking of eroded part of bed plate, and produced satisfactory results, too. Finally, the algorithm was tested to a movable-bed laboratory experimental conditions. The shoreline movement behind detached breakwater was reasonably reproduced with this algorithm.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.2
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• pp.77-86
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• 2017

Selection of location in food service start-up business is sure to be a shortcut to achievement of business performance, and in this context, it's no exaggeration to say that food service industry is an real estate industry. This study looked into what influence of the location factor in food service start-up business had on sales performance, and intended to verify whether the location factors ultimately influenced business performance consequent on the influence of location factors on start-up business satisfaction. To this end, this study set food service owner-operators as its research subject, and conducted a survey of the operators (of restaurants) located in Anyang-si from December 1, 2016 until January 30, 2017. This study distributed a total of 300 copies of questionnaires, and collected 245 copes, among which this study used 198 copies for empirical study excluding the copies whose reply was unfaithful. This study did empirical analysis of 198 copies using SPSS 22.0 Statistical Package Program, together with the application of frequency analysis, factor analysis and regression analysis. The major results of this study are as follows: First, this study divided the location factors in food service start-up business stores into the four, i.e. accessibility, clustering property, placeness and visibility, etc. Second, the study results showed that accessibility, clustering property, placeness and visibility had significant influence as one in the influence of locational factors on sales performance. Third, this study could understand that start-up business satisfaction had a partial mediated effect in the influence of location factors on sales performance. Resultantly, this study confirmed food service start-up business's own selection of location, and wished to find major factors and a differentiated point in time of selection of location of stores in other fields. Such a result gives an implication that it's necessary to concentrate all efforts to increase sales performance of food service start-up business from the location selection phase, and to make efforts to increase start-up business satisfaction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.501-511
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• 2014

Bio-oil derived from biomass through fast pyrolysis process has the potential to displace a significant amount of petroleum fuels. However, the use of bio-oil in a diesel engine is very limited because of its poor properties, e.g., its low energy density, low cetane number, and high viscosity. Therefore, bio-oil should be emulsified or blended with other fuels that have high centane numbers. Because bio-oil has poor miscibility with petroleum fuels, the most suitable candidate fuels for direct mixing are alcohol fuels. In this study, bio-oil was blended with ethanol, and two types of cetane improvers were added to a blended fuel to improve the self-ignition property. The two types of cetane improvers, PEG 400 and 2-EHN, made it possible for bio-oil blended fuels to combust in a diesel engine with a maximum bio-oil content of 15 wt%. A high-compression-ratio piston is also proposed for the combustion of bio-oil in a diesel engine.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.3
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• pp.41-63
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• 2004

The area covered by product liability in broadest sense is so vast that an attempt to analyse all its impact on the aviation world risk. Every effort has been made to confine our review of subject a closely as possible to its influence on aircraft manufacturers, airlines and passengers, in spite of strong connections with other spheres of commercial. Product Liability in aviation is the liability of aircraft's manufacturer, processor or non-manufacturing seller for injury to the person or property of a buyer or third party caused by a product which has been sold. Here-in a product is aircraft, third party is passengers who suffered damage by defective design, defective construction, inadequate instructions for handling in aircraft. Whenever a product turns out to be defective after it has been sold, there are under Anglo-American law three remedies available against the aircraft's manufacturer (1) liability for negligence (2) breach of warranty (3) strict liability in tort. There are Under continental law Three remedies available against the aircraft's manufacturer (1) liability for defective warranty (2) liability for non-fulfillment of obligation (3) liability in tort. It is worth pointing out here an action for breach of warranty or for defective warranty, for non-fulfillment of obligation is available only to direct purchaser on the basis of his contract with the aircraft's manufacturer, which of course weakness its range and effectiveness. An action for tort offers the advantage of being available also to third parties who have acquired the defective product at a later stage. In tort, obligations are constituted not only by contract, but also by stature and common law. In conclusion, There in no difference in principle of law. In conclusion I would like to make few suggestions regarding the product liability for aircraft's manufacturer. Firstly, current general product liability code does not specify whether government offices(e.g. FAA) inspector conducted the inspection and auditory certificate can qualify as conclusive legal evidence. These need to be clarified. Secondly, because Korea is gaining potential of becoming aircraft's manufacturer through co-manufacturing and subcontracting-manufacturing with the US and independent production, there needs legislation that can harmonize the protection of both aircraft's manufacturers and their injured parties. Since Korea is in primary stage of aviation industry, considerate policy cannot be overlooked for its protection and promotion. Thirdly, because aircraft manufacturers are risking restitution like air-carriers whose scope of restitution have widened to strict and unlimited liability, there needs importation of mandatory liability insurance and national warranty into the product liability for aircraft's manufacturers. Fourthly, there needs domestic legislation of air transportation law that clearly regulates overall legal relationship in air transportation such as carrier & aircraft manufacturer's liability, and aviation insurance.

• Journal of Korea Technology Innovation Society
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• v.15 no.2
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• pp.242-261
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• 2012

Early stages of technology valuation have been often overlooked or under-represented. The early stage technologies are even riskier due to their inadequacy of commercial development and market applicability. More than 95% of patents fail to earn any revenues so that the majority of patents were valueless. Technology transfers from laboratories at universities and research institutes to industrial firms have increased to acquire value from invented technologies. Technology transfer, a process of transferring discoveries and innovations resulted from research to commercial sectors, typically comprises several steps: disclosing the discoveries and innovations, i.e., intellectual property (IP), evaluating the IP's economic prospects, securing a patent, copyright or trademark for the IP, commercializing the technology through licensing, forming a joint venture, or selling. At each of those stages in the research and development of technology, the value of technology would play a very important role of making decision on the movement toward the next step, however, the financial value of technology is not easy to determine due to a great amount of uncertainty in the course of research and development, and commercialization. This paper refers to technology embodied as devices, equipment, software or processes primarily developed at public research institutions such as universities. Sometimes it is also as the result of externally financed projects contracted with industry. Nearly always technology developed at public research entities results in laboratory prototypes. When it is required to define the technology transfer contract terms for the license of the university patrimonial rights to external funding companies or other interested parties, a question arises: what is the monetary value? In this paper, we present a method for technology valuation based on the identification of specific value points related to its development. The final technology value must be within previously defined value limits. This paper consists of the review of issues related to technology transfer and commercialization, the identification of characteristics of technologies in the early stage of technology development, the formulation of framework of methods to value the early stage technologies, and the conclusion and implication of the previous review.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.53-61
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• 2008

Public Key Broadcast Encryption (PKBE) allows a sender to distribute a message to a changing set of users over an insecure channel. PKBE schemes should be able to dynamically exclude (i.e., revoke) a certain subset of users from decrypting a ciphertext, so that only remaining users can decrypt the ciphertext. Another important requirement is for the scheme to be forward-secrecy. A forward-secure PKBE (fs-PKBE) enables each user to update his private key periodically. This updated private key prevents an adversary from obtain the private key for certain past period, which property is particularly needed for pay-TV systems. In this paper, we present a fs-PKBE scheme where both ciphertexts and private keys are of $O(\sqrt{n})$ size. Our PKBE construction is based on Boneh-Boyen-Goh's hierarchical identity-based encryption scheme. To provide the forward-secrecy with our PKBE scheme, we again use the delegation mechanism for lower level identities, introduced in the BBG scheme. We prove chosen ciphertext security of the proposed scheme under the Bilinear Diffie-Hellman Exponent assumption without random oracles.

• Journal of Powder Materials
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• v.28 no.2
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• pp.143-149
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• 2021

In this study, (GaN)_1-x(ZnO)_x solid solution nanoparticles with a high zinc content are prepared by ultrasonic spray pyrolysis and subsequent nitridation. The structure and morphology of the samples are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The characterization results show a phase transition from the Zn and Ga-based oxides (ZnO or ZnGa₂O₄) to a (GaN)_1-x(ZnO)_x solid solution under an NH3 atmosphere. The effect of the precursor solution concentration and nitridation temperature on the final products are systematically investigated to obtain (GaN)_1-x(ZnO)_x nanoparticles with a high Zn concentration. It is confirmed that the powder synthesized from the solution in which the ratio of Zn and Ga was set to 0.8:0.2, as the initial precursor composition was composed of about 0.8-mole fraction of Zn, similar to the initially set one, through nitriding treatment at 700℃. Besides, the synthesized nanoparticles exhibited the typical XRD pattern of (GaN)_1-x(ZnO)_x, and a strong absorption of visible light with a bandgap energy of approximately 2.78 eV, confirming their potential use as a hydrogen production photocatalyst.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.4
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• pp.266-274
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• 2024

In this paper, we designed a low-area 32-bit PF (Poly-fuse) OTP IP, a non-volatile memory that stores data required for analog circuit trimming and calibration. Since one OTP cell is constructed using two PFs in one select transistor, a 1cell-2bit multibit PF OTP cell that can program 2bits of data is proposed. The bitcell size of the proposed 1cell-2bit PF OTP cell is 1/2 of 12.69㎛ × 3.48㎛ (=44.161㎛2), reducing the cell area by 33% compared to that of the existing PF OTP cell. In addition, in this paper, a new 1 row × 32 column cell array circuit and core circuit (WL driving circuit, BL driving circuit, BL switch circuit, and DL sense amplifier circuit) are proposed to meet the operation of the proposed multbit cell. The layout size of the 32bit OTP IP using the proposed multibit cell is 238.47㎛ × 156.52㎛ (=0.0373㎛2) is reduced by about 33% compared that of the existing 32bit PF OTP IP using a single bitcell, which is 386.87㎛ × 144.87㎛ (=0.056㎛2). The 32-bit PF OTP IP, designed with 10 years of data retention time in mind, is designed with a minimum programmed PF sensing resistance of 10.5㏀ in the detection read mode and of 5.3 ㏀ in the read mode, respectively, as a result of post-layout simulation of the test chip.