• Steel and Composite Structures
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• 제15권2호
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• pp.203-220
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• 2013

The study of the tensile strength of composite materials is far more complex than analysis of the properties of elasticity and plasticity. Indeed, during mechanical loading, micro-cracks in the matrix, the fibers break, debonding of the interfaces are created. The failure process of composites is of great diversity and cannot be described if even we know: the strength criterion of each individual component, the state of stress and strain in the material, the propagation phenomena cracks in the structure and nature of the interface between the matrix and the reinforcement. This information is only partially known and the obtained by the analysis of a stress limit beyond which there is destruction of the material is almost impossible. To partially process the issue, a solution lies in a mesoscopic approach of seeking a law to locate the ultimate strength of the material for a plane stress state. Tests on rectangular plates in bending PEEK/APC2 and T300/914 three were made and this in order to validate our approach, the calculation has been implemented in a nonlinear finite element code (Castem 2000), in order to make comparison with the numerical results. The results show good agreement between numerical simulation and the two materials; however, it would be interesting to consider other phenomena in the criterion.

• 한국압력기기공학회 논문집
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• 제16권1호
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• pp.30-36
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• 2020

In SMART, the flow mixing header assembly (FMHA) is used to mix the coolant flowing into the reactor core to maintain a uniform temperature. The FMHA is designed to have enough stiffness so the resonance with reactor internal structures does not occurs during the pipe break and the seismic accidents. Since the gap between the FMHA and the core support barrel assembly is very narrow compared with the diameter of FMHA, the hydrodynamic mass effect acting on the FMHA is not negligible. Therefore the hydrodynamic mass characteristics on the FMHA are investigated to consider the fluid and structure interaction effects. The result of modal analysis for the dry and underwater conditions, the natural frequency of primary vibration mode for the horizontal direction is reduced from 136.67 Hz to 43.76 Hz. Also the result of frequency response spectrum seismic analysis for the dry and underwater conditions, the maximum equivalent stress are increased from 13.89 MPa to 40.23 MPa. Therefore, reactor internal structures located in underwater condition shall consider carefully the hydrodynamic mass effects even though they have sufficient stiffness required for performing its functions under the dry condition.

• Journal of Biosystems Engineering
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• 제34권4호
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• pp.220-227
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• 2009

In the process of oyster mushroom production, loading work of culture medium needs the most intensive labor power. Therefore, development of culture medium machine causes to reduce the manpower and cost. The main objective of this study is to develop the culture medium loading machine and investigate the optimal operation conditions and to evaluate the economic value of the machine. The results are summarized as follows: 1. Optimum transporting velocity of the conveyor was 0.61 m/s 2. Optimum speed of blower was 3183 rpm at the transporting velocity of 0.61 m/s with the loading quantity of 3.41 t/hr 3. Recommendable opening area ratio of pressure controller was 1/2 at the blower speed of 3183 rpm and the transporting velocity of 0.61 m/s 4. The break even point resulted in $240\;m^2$ of cultivating area compared to the method of with portable workbench, and $350\;m^2$ of cultivating area compared to the method of with a tractor and a truck.

• 설비공학논문집
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• 제26권4호
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• pp.145-150
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• 2014

Many studies are being conducted with the aim of reducing the energy consumption in data centers, which are one of the highest consumers of energy. The use of an air-side economizer system that uses external air during intermediate and winter seasons is being considered for reducing the energy consumption of air conditioners. In this study, using the energy simulation, we evaluated the energy performance of a central chilled water cooling system and air-side economizer system in domestic data centers. Further, the cost-effectiveness of the air-side economizer was analyzed through Life-Cycle Cost Analysis. The results showed that with the use of air-side economizer systems, the energy costs increased as the applied filter grade increased; however, unlike existing central chilled water systems, it would break even within 2 years.

• 대한건축학회논문집:구조계
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• 제34권4호
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• pp.65-74
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• 2018

The primary objective of this study is to develop a conceptual design of automated pothole patching machine that improves the conventional work in safety, quality, and productivity. For this, the following research works are conducted sequentially; 1)literature review, 2)selection of element technology for conceptual design, 3)deduction of work process and conceptual design, 4)life cycle cost analysis of the conceptual design. As a result, X-Y table telescopic manipulator, pothole patching end effector, realtime pothole recognizer, 3D pothole volume profiler, automated pothole patching machine controller are selected as core technologies. Furthermore, a conceptual design and working process of an automated pothole patching machine are developed based on the core technologies. According to the life cycle cost analysis result, the cost of the automated method was 38.3% less than that of the conventional method, and the economic efficiency was also superior(ROR 77.1%, Break-even Point 23.8month). It is expected that the application range and impact on the construction industry will be enormous due to the increasing trend of road maintenance market.

• 대한건축학회논문집:구조계
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• 제35권2호
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• pp.37-44
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• 2019

The primary objective of this study is to develop a prototype of all-in-one attachment-based PHC pile head cutting robot that improves the conventional work in safety, productivity, and quality. For this, the following research works are conducted sequentially; 1)literature review, 2)development of an all-in-one attachment-based PHC pile head cutting robot prototype, 3)performance evaluation of each device, 4)economic analysis of an automated method. As a result, PHC pile cutting level sensing device, PHC pile cutting device, PHC pile handling device are developed. Futhermore, working process of an automated method is developed based on result of performance evaluation. According to the economic analysis result, the cost of the automated method was 21.37% less than that of the conventional method, and the economic efficiency was also superior(ROR 215.44%, Break-even Point 5.52month). It is expected that conclusions for future improvements are used in the development of the all-in-one attachment-based PHC pile head cutting robot to practical use.

• 지능정보연구
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• 제22권4호
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• pp.69-85
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• 2016

연인과의 성공적인 관계형성은 인생의 만족감을 결정짓는 핵심적인 요소 중 하나이다. 기존에 심리학 분야에서는 성공적인 연인관계에 영향을 미치는 요인들에 대한 다양한 연구가 수행되어 왔으나, 주로 통계적인 분석기법에 기반하고 있기 때문에 복잡한 비선형의 관계를 분석하고, 특징을 추출하는 데에는 한계가 있었다. 이에, 본 연구는, 기존의 통계적인 분석 기법과 더불어, 데이터마이닝의 의사결정나무 분석기법을 활용하여 사랑의 형태에 따른 연인관계의 몰입(commitment) 수준과 관계지속 여부를 분석하였다. 특히, 기존 연구에서 도출된 주요 변인들 이외에 사랑의 여섯 가지 형태인 에로스(eros), 루두스(ludus), 스트로게(storge), 매니아(mania), 프래그마(pragma) 그리고 아가페(agape)를 추가적으로 고려하여, 이들이 연인관계에서 서로에 대한 몰입수준 및 연인관계 지속여부에 어떠한 영향을 미치는지 분석하고, 예측하는 모형을 수립하였다. 본 연구에는 실제 남녀커플 105쌍, 총 210명에 대한 데이터가 활용되었다. 본 연구결과 연인관계 몰입수준 및 관계 지속여부의 영향요인으로, 기존에 심리학 분야에서 제시된 변수들 이외에, 에로스, 아가페, 프래그마 등이 유의한 영향을 미친다는 것을 확인하였다. 특히, 남성은 아가페적 사랑의 형태가 몰입에 중요한 영향을 미치는 반면, 여성은 에로스적 사랑의 형태가 더욱 중요한 영향을 미치는 것으로 나타났다. 또한, 연인관계 지속여부에는 남성의 나르시시즘, 만족, 투자 및 매니아적 성향이 영향을 주고 있는 것으로 나타난 반면, 여성의 경우, 여성이 남성을 매니아적으로 사랑하는 정도만이 영향을 주고 있어, 남성이 관계의 지속 또는 결별에 더욱 결정적인 영향을 미치고 있는 것을 알 수 있었다. 이러한 연구는 데이터마이닝의 적용분야를 심리학 영역으로 확장한 융합연구로, 연인관계에 대한 새로운 분석을 시도하였다는 점에서 의의가 있으며, 조화로운 연인관계를 형성하는데 실질적인 시사점을 제공할 수 있을 것으로 기대된다.

• 한국통신학회논문지
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• 제36권3B호
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• pp.240-247
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• 2011

본 논문은 U-City (Ubiquitous City)의 무선망을 구축하는데 있어 WLAN 기반의 무선망과 WiBro 기반의 무선망을 고려하고 각 방식을 통해 구축할 경우 소요되는 비용과 얻을 수 있는 편익을 분석하여 경제적 효율성이 높은 무선망 방식을 선정하는 방법론을 제시하였다. 비용 분석을 위한 기초 데이터 획득을 위해 셀 설계 및 커버리지 분석을 수행하였으며, WiFi와 WiBro의 기술적 특정을 바탕으로 편익 분석을 수행하였다. 비용-편익 분석 결과 WiBro 무선망의 손익분기점이 WiFi 무선망에 비해 1.75년 빨리 도달하며, NPV(Net Present Value)도 114억원 가량 큰 것으로 나타나 경제적으로 효율적인 무선망 방식으로 분석되었다.

• 산업경영시스템학회지
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• 제44권3호
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• pp.39-49
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• 2021

The Korean Air-Force aircraft maintenance depot paints the exterior of various aircraft, including high-tech fighters. Aircraft exterior painting is a maintenance process for long-term life management by preventing damage to the aircraft surface due to corrosion. The de-painting process is essential to ensure the quality of aircraft exterior paints. However, because the Korean Air-Force's de-painting process is currently done with sanding or Plastic Media Blasting (PMB) method, it is exposed to harmful dust and harmful compounds and consumes a lot of manpower. This study compares the de-painting process currently applied by the ROK Air-Force and the more improved process of the US Air Force, and performs economic analysis for the introduction of advanced equipment. It aims to provide information that can determine the optimal time to introduce new facilities through Cost-Volume-Profit (CVP) analysis. As a result of the analysis, it was confirmed that the sanding method had the most economical efficiency up to 2 units per year, the PMB method from 3 to 21 units, and the laser method from 22 units or more. In addition, in a situation where the amount of de-painting work is expected to increase significantly due to the increase in fighters in future, BEP analysis was conducted on the expansion of the existing PMB method and the introduction of a new laser method. As a result of the analysis, it was confirmed that it is more economical to introduce the laser method when the amount of work exceeds the PMB work capacity(18 units per year). The paper would helpful to improve the productivity and quality of the Korean Air Force Aircraft maintenance depot through timely changes of facilities in the workplace in preparation for expansion.

• 한국정보시스템학회지:정보시스템연구
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• 제20권2호
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• pp.109-134
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• 2011

The purpose of this paper is to present an overview of the characteristics of the e-sports business at a crucial point in the era of information and knowledge. That is, an investigation was conducted surrounding the key success factors of e-sports as a newly growing industry, and the relationship between the key success factors and the usage effect. In order to do this, the key success factors were extracted from interviews with e-sports experts in conjunction with a survey that was conducted to gather empirical data. The key points of the statistical analysis of the survey are as follows. First, the success factors of a policy do not have a significant effect on the usage. Second, some administrative success factors of the e-sports business include the distribution of e-sports in the form of franchise chain, the establishment of policies to prevent the excellent members of e-sports from seceding, making a good impression as a high-class sport, the frequent notice of the break-even point, and educating people on how to use the e-sports machine. Third, the development and distribution of excellent e-sports software was analyzed as a technical success factor of the e-sports business. Finally, there is no doubt that results of this study can be used to facilitate the growth of the e-sports business as a new industry related to the IT industry.