• Journal of the korean Society of Automotive Engineers
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• v.11 no.1
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• pp.31-43
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• 1989

The paper shows a solution by giving vegetable oil a chemical treatment, i.e., transesterification of the rapeseed oil without any modification of the diesel engine for reducing carbon deposits, and to evaluate rate of combustion with vegetable oils, their esterified fuel and their blend fuels using a double Wiebe's function approximation in a naturally aspired D.I. diesel engine. Since any oil will be as material for ester, if it is fatty acid, the sardine oil was considered. In the experiment, engine performance, exhaust gas emissions, and combustion characteristics were measured and calculated for a number of fuels: rapeseed oil, palm oil, ester of rapeseed oil, and these fuels blended with ethanol or diesel fuel.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.67-76
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• 1992

A procedure to determine the axle load limits of asphalt concrete pavements are proposed in this study. Axle load limits are determined by calculating maximum tensile strains at the bottom of the asphalt stabilized base layer and maximum vertical strains at the top of the subgrade. In order to investigate the efficiency of axle configuration, calculated influence line of wheel load on domestic expressway pavement system is used. Limiting strains are selected through the analysis of conventional failure criteria. From the analysis of axle load limits about axle composition(single-axle, tandem-axle, tridem-axle), it is found that the axle load limits of tandem-axle and tridem-axle can be calculated by muitipling the axle load limits of single-axle by axle numbers and that axle load limits are closely related to the thickness of each layer of pavement structure. It is also found that the axle load limits by tensile strains are more critical than those by vertical strains on asphalt concrete pavement models of YOUNG-DONG, KYONG-IN and KYONG-BU expressways.

• Journal of Information Management
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• v.41 no.2
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• pp.161-181
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• 2010

The purpose of this study is to investigate citation behavior in internet news to research papers of 10 domestic economic institutes and to suggest institutes' impact quantitatively with h-index and various modified indices. Content analysis of 878 news articles that collected from NAVER news site was performed. First, as citing behavior, cited numbers of research papers, preferred news media, speed, source entry accuracy, centrality, subject section, and length by the institutes were examined. Next, impact indices for institutes were calculated by cited numbers using h-index, g-index, $h_s$-index, and $g_s$-index, and the ranking of 10 research institutes were determined by each impact indices. As a result, institutes belonged to upper ranks showed little variation among the different indices. On the other hand, institutes belonged to middle and lower ranks showed variations in impact indices and experts' survey.

• Journal of the Health Care and Life Science
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• v.11 no.2
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• pp.375-380
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• 2023

This study aims to develop a laryngoscope that can more quickly remove foreign substances in the mouth and perform endotracheal intubation and confirm its usefulness. A laryngoscope suitable for the purpose was manufactured and conducted on 30 fourth-year students at H University. The experimental method was to perform oral suction and endotracheal intubation after inserting a laryngoscope when there was no foreign material, and when there was a foreign material, endotracheal intubation was performed using a laryngoscope with an aspirator attached. When a foreign body was present, suction was performed using the existing method and the developed integrated laryngoscope. The suction time was shorter when the integrated laryngoscope was used than the existing method, and a statistically significant difference was found (p< .000). In the case of the time required for endotracheal intubation, the time required for endotracheal intubation was shorter when the integrated laryngoscope was used than the conventional method, and a statistically significant difference was found (p< .000). The development of an integrated laryngoscope with an aspirator is a useful device that can more effectively remove foreign substances and perform endotracheal intubation when there are foreign substances in the mouth.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1222-1230
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• 2022

The rotor blade is an important component of a tidal stream turbine and is affected by a large thrust force and load due to the high density of seawater. Therefore, the performance must be secured through the geometrical and structural design of the blade and the blade structural safety to which the composite material is applied. In this study, a 1 MW class large turbine blade was designed using the blade element momentum (BEM) theory. GFRP is a fiber-reinforced plastic used for turbine blade materials. A sandwich structure was applied with CFRP to lay-up the blade cross-section. In addition, to evaluate structural safety according to flow variations, static load analysis within the linear elasticity range was performed using the fluid-structure interactive (FSI) method. Structural safety was evaluated by analyzing tip deflection, strain, and failure index of the blade due to bending moment. As a result, Model-B was able to reduce blade tip deflection and weight. In addition, safety could be secured by indicating that the failure index, inverse reserve factor (IRF), was 1 or less in all load ranges excluding 3.0*Vr of Model-A. In the future, structural safety will be evaluated by applying various failure theories and redesigning the laminated pattern as well as the change of blade material.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.2
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• pp.1-8
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• 2015

Dual pulse rocket motor is a variant of solid rocket motor with two propellant grain separated by a pulse separation device. The major performance of such a rocket motor is influenced by the change in the hole area of pulse separation device to nozzle throat area ratio. In this study, we performed flow analysis to investigate the internal flow characteristics according to the pulse separation device hole area to nozzle throat area ratio change. Gases used flow analysis were used combustion gas of HTPB/AP composite propellant and nitrogen gas. Flow analysis results of the dual pulse rocket motor were validated by comparison with experimental results of pneumatics. Commercial CFD code ANSYS FLUENT 14.5 is used in this study to simulate flow analysis.

• Journal of Advanced Navigation Technology
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• v.28 no.1
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• pp.51-59
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• 2024

Currently, the approved training organization (ATO) is being used worldwide to supply excellent pilots in the aviation industry. This system, which is used worldwide, has been transformed and utilized according to each country. In this study, the operation method and educational environment of specialized pilot training institutions in Korea were examined in detail, and the differences were compared by comparing the operation methods and flight education environments of international standards, the United States, Europe, Canada, and neighboring countries such as Japan, China, and Singapore to derive differences from the system of specialized educational institutions in Korea. Based on these comparative data, through a survey of workers in the relevant work, satisfaction with the number of department classes set by the domestic aviation safety law specialized educational institution designation standards differed greatly depending on the characteristics of the survey subjects, and the importance differed depending on the department's class subjects.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.63-71
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• 2009

The elastic effects of the valve train components are analyzed by using the finite element models of the rocker arm and valve. The whole equations of motion of the valvetrain of an internal combustion engine formulated by finite element techniques are solved by imposing the contact conditions with the augmented Lagrange multiplier method. The velocity and acceleration constraints as well as the displacement constraints are imposed on the contact points. The numerical simulations show that, even if the magnitude of the elastic deformation of the components is very small, it may have large effects on the valvetrain dynamics of a high-speed engine.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2085-2088
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• 2003

인터넷의 발전과 함께 사용자 인증 기술도 발전하였다. 이러한 사용자 인증 기술 중 패스워드 인증기술이 특정 컴퓨터 또는 통신 시스템 서버의 서비스를 요구하는 클라이언트의 신분을 확인하는 기술로 가장 널리 사용되고 있다. 그러나 일반적으로 사용되는 패스워드 인증의 약한 안전성으로 인한 보안 사고는 매년 증가하고 있고, 그 피해 또한 상당하다. 본 논문은 이런 패스워드 인증 방식 중 강한 인증으로 분류되는 AKE 프로토콜에 대해 분석하고, man-in-the-middle attack이 가능하다는 것을 보인 후, 이 취약점을 보완하여 제 3의 신뢰기관을 두지 않고 두 파티간의 상호인증이 가능한 변형된 AKE 프로토콜을 제안한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.3
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• pp.13-19
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• 2007

This paper described design method to minimize the crosstalk effect of multiaxis thrust measurement stand which can measure the thrust vector control performance of Solid Rocket Motor. This paper presents a theoretical solution for predicting the magnitude of crosstalk and calculates design sensitivity. The results indicate that the most important parameter of crosstalk is the displacement of flexure-loadcell-flexure assembly. And shape, dimension and mechanical properties of flexure and loadcell can also influence the magnitude of crosstalk.