• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.739-748
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• 2017

Notches such as slots are typical geometric features on mechanical components that promote fatigue crack initiation. Unlike for components with open hole type notches, there are no conventional treatments to enhance fatigue behavior of components with slots. In this work we evaluate the viability of applying laser shock peening (LSP) to extend the fatigue life of 6061-T6 aluminum components with slots. The feasibility of using LSP is evaluated not only on damage free notched specimens, but also on samples with previous fatigue damage. For the LSP treatment a convergent lens was used to deliver 0.85 J and 6 ns laser pulses 1.5 mm in diameter by a Q-switch Nd: YAG laser, operating at 10 Hz with 1064 nm of wavelength. Residual stress distribution was assessed by the hole drilling method. A fatigue analysis of the notched specimens was conducted using the commercial code FE-Safe and different multiaxial fatigue criteria to predict fatigue lives of samples with and without LSP. The residual stress field produced by the LSP process was estimated by a finite element simulation of the process. A good comparison of the predicted and experimental fatigue lives was observed. The beneficial effect of LSP in extending fatigue life of notched components with and without previous damage is demonstrated.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.305-310
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• 2003

This study is intended to outline the lessons that can be learned from European experience of the opportunities and challenges involved in operating train ferries to carry freight. The study considers the various train ferry routes that have operated over recent years in Europe, examines their characteristics, and then proceeds to evaluate the economic viability of train ferries in general. On the basis of this analysis, we have attempted to outline the conditions that appear to be required under which Train Ferries may be competitive. This study shows that long crossing train ferries in Europe have survived where the adjacent railway systems handle a significant volume of domestic traffic and do themselves playa serious role in the transport industry. There is no reason to suppose railway wagons cannot be carried economically over long distances. Experience in Western Europe is that they are best operated as mixed road trailer and rail wagon services. Only the lower deck need carry railway wagons, which greatly simplifies loading and the physical construction of the ship. Existing road based ro-ro ferries can be adapted to become rail ferries. It is, however, essential that there is commercial clarity as to the responsibility for ensuring the overall service is viable. To that end, the ferry company is responsible for marketing the service and managing relationships between the two railway authorities.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.264-273
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• 2005

Broadband power line communications have been receiving tremendous interest In recent years because this technology enables utilities to deploy a communication network over existing power line infrastructures. Despite the enormous potential, there is some skepticism about the technology and its commercial viability. In this paper, we investigate the performance characteristic of PLC through field test carried out in actual households. Also it addresses major field deployment aspects, such as range, coverage, the number of node for operation and maintenance.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.64-69
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• 2009

Because of their low operating and maintaining costs, ground-source heat pump(GSHP) systems are an increasingly popular choice for providing heating, cooling and water heating to public and commercial buildings. Despite these advantages and the growing awareness, GSHP systems to residential sectors have not been adopted in Korea until recently. A feasibility study of a residential GSHP system was therefore conducted using the traditional life cycle cost(LCC) analysis within the current electricity price framework and potential scenarios of that framework. As a result, when the current residential electricity costs for running the GSHP system are applied, the GSHP system has weak competitiveness to conventional HVAC systems considered. However, when the operating costs are calculated in the modified price frameworks of electricity, the residential GSHP system has the lower LCC than the existing cooling and heating equipments. The calculation results also show that the residential GSHP system has lower annual prime energy consumption and total greenhouse gas emissions than the alternative HVAC systems considered in this work.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5111-5116
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• 2014

Computed Tomography Colonography (CTC) is a medical imaging technology used in identifying polyps and colon cancer masses in the large intestine. The technique has evolved a great deal since its invention and has become a routine diagnostic procedure in Western countries due to its non invasiveness and ease of use. The objective of our study was to explore the possibility of CTC application in Indian hospitals. This paper gives an overview of the procedure and its commercial viability. The explanation begins with the domain aspects from gastroenterologist perspective, the new way of thinking in polyp classification, the technical components of CTC procedure, and how engineering solutions have helped clinicians in solving the complexities involved in colon diagnosis. The colon cancer statistics in India and the results of single institution study we carried out with retrospective data is explained. By considering the increasing number of patients developing colon malignancies, the practicality of CTC in Indian hospitals is discussed. This paper does not reveal any technical aspects (algorithms) of engineering solutions implemented in CTC.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.852-857
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• 2010

In this paper, we proposed and demonstrated an indoor visible-light communication system using an array of light-emitting diodes (LEDs). The main idea is based on that the LEDs can be used not only for lighting but also for free-space optical communications. Because LEDs offer advantageous properties such as high brightness, reliability, lower power consumption and long lifetime, the indoor visible-light communication systems are going to provide high quality of service by the high radiation power of the LED lighting. Prototype of simplex channel for audio and the full-duplex channel for text message were developed. Results indicates the viability of creating inexpensive free-space optical communication transceivers that might be embedded in commercial light products to supports indoor wireless networking.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.75-80
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• 1997

An ethanolic fermentation process was developed for preparing Doenjang with high ethanol. Higher and efficient viable cell production of salt-tolerant ethanolic yeast is a prerequisite for the successful commercial-scale process of ethanol production during Doenjang fermentation. Culture conditions of salt-tolerant yeast, S. cerevisiae KFCC 10823, was studied in terms of the effect of several environmental and nutritional factors. Viable cell numbers were the highest in a medium containing the following components per liter of water: soysauce, 300ml; dextrose, 50 g; beef extract, 5 g; yeast extract, 5 g; $KH_2PO_4$, 5 g; NaCl, 50 g. The optimal culture conditions of S. cerevisiae KFCC 10823 were pH 5.5, $25^{\circ}C$, 200 rpm and 0.5 vvm. Yeast viability during batch fermentation was gradually decreased to a level less than $90{\%}$ after 35 hours. The maximum cell number was $2.2{\times}10_7$ cells/ml at the optimal condition. Doenjang prepared with ethanolic yeast was ripened after 45 days at $30^{\circ}C$. This Doenjang contains 470 mg% of amino nitrogen and 2.5% ethanol. The shelf-life at $30^{\circ}C$ was theoretically estimated as 444 days.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2003.11a
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• pp.117-118
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• 2003

This experiment was conducted to investigate the effect of feed restriction in early stage of growth on the compensatory growth in male and female broiler chickens. Day-old 480 male and 480 female commercial broiler chickens(Ross strain) were randomly allotted to 32 pens(replicates), 30 birds per pen, to compare the sex difference in growth performance and carcass characteristics. Birds in control group(C) were full fed throughout the study. T1, T2 and T3 were restricted at 4∼11d, 4∼14d and 4∼18d, respectively. Chickens were weighed every week, and one bird was selected from each pen to measure carcass characteristics at the end of experiment. In female chickens, all restricted-fed groups except for T3 weighed same as or heavier than the control group at 7 weeks of age. In male chickens, both T2 and T3 that had longer feed restriction period were significantly different from the control group. Viability was not different significantly. Feed intake in both male and female chickens of T3 group statistically differed from the control group. The female chicks showed larger abdominal fat pad sizes than did male birds up to market age.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2329-2333
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• 2022

Base metal corrosion forms a significant issue during the chemical decontamination of the primary coolant loop in nuclear power plants as it is directly related to the economic and safety viability of decommissioning. In this technical note, potentiodynamic evaluations of several base metals (304 stainless steel, SA106 Grade B carbon steel, and alloy 600) were performed to determine their corrosion behavior during the hydrazine (N₂H₄)-based reductive ion decontamination (HyBRID) process. The results suggested that N₂H₄ protected the surface of the base metals in the HyBRID solution, which is primarily composed of H₂SO₄. The corrosion resistance of the carbon steel was further improved through the addition of CuSO₄ to the solution. The corrosion rate of carbon steel in the H₂SO₄-N₂H₄-CuSO₄ solution was lower than that exhibited in an oxalic acid solution, a commonly used reaction medium during commercial decontamination processes. These results indicate the superiority of the HyBRID process with respect to the base metal stability.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.3
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• pp.281-301
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• 2023

The shipboard combat system is a key system for naval combat that supports a command and control process cycle consisting of Detect - Control - Engage in real time to ensure ship viability and conduct combat missions. Modern combat systems were developed on the basis of Open Architecture(OA) to maximize acceptance of latest technology and interoperability between systems, and actively introduced the COTS(Commercial-of-the-shelf). However, as a result of that, vulnerabilities inherent in COTS SW and HW also occurred in the combat system. The importance of combat system cybersecurity is being emphasized but cybersecurity research reflecting the characteristics of the combat system is still lacking in Korea. Therefore, in this paper, we systematically identify combat system threats by applying Data Flow Diagram, Microsoft STRIDE threat modelling methodology. The threats were analyzed using the Attack Tree & Misuse case. Finally we derived the applicable security requirements which can be used at stages of planning and designing combat system and verified security requirements through NIST 800-53 security control items.