• 한국전자통신학회논문지
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• 제6권3호
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• pp.405-410
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• 2011

단조산업에서의 철강제품의 열처리는 산업의 근간이 되며 제품경쟁력에 아주 중요한 부분을 차지한다. 열처리를 수행하는 열처리로에서의 버너제어는 연료인 LNG가스의 절감뿐만 아니라 균질한 열처리를 요구하는 제품 경쟁력에 막대한 영행을 준다. 본 연구는 열처리로에서의 버너제어를 비례제어를 이용하여 수행하고, 그 결과가 에너지 절감뿐만 아니라 열처리로의 성능을 향상시키는 것을 보여준다.

• 융합정보논문지
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• 제8권5호
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• pp.251-261
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• 2018

중국은 ICT 기술의 발전에 힘입어 스마트 농업분야에서 선진국을 급격히 추격하고 있다. 본 논문에서는 추격이론을 이용하여, 중국의 양대 국가 전략인 중국제조2025와 일대일로 전략이 스마트농업을 발전시키는데 있어서 어떻게 "기회의 창"을 제공하는지 분석하고자 한다. 시간 차원의 기술 선진화 전략인 '중국제조2025'와 공간 차원의 시장 확대 전략인 '일대일로' 정책이 T자형 상승 작용을 이루어 스마트 농업의 발전을 이끌고 있음을 단계 생략형, 경로 창출형, 경로 추종형 3가지 유형으로 나누어 설명하였다. 한국 스마트 농업의 주요 수출 시장이며, 글로벌 시장에서 강력한 경쟁자인 중국 스마트 농업에 대한 이해를 통해 한국 스마트 농업의 해외진출 전략에 대한 시사점을 도출하였다.

• 한국화재소방학회논문지
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• 제16권2호
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• pp.8-13
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• 2002

유도가열 기술은 담금질, 단조를 위한 예열, 용융 그리고 요리 등과 같은 산업 전반에 걸쳐서 아주 폭넓게 사용되는 기술이다. 본 논문에서는 IH-JAR의 효과적인 설계를 위하여 자계 및 열 해석을 하였다. IH-lAR의 내부자계는 3차원 축대칭 유한요소법을 사용하여 해석하였으며, 열원은 IH-JAR 내부에서 유도된 와전류에 의하여 발생되고, 열은 열원과 열방정식을 사용하여 계산되어진다. 또한, IH-JAR의 온도분포를 시간과 투자율에 따라 제시하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.677-684
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• 2006

An ejector is a fluid transfer device to be used for mixing of fluids, maintaining vacuum, and overcoming a poor suction condition. To date, most ejectors have been made from the casting process. which is time-consuming and high-cost process. Therefore, a new production method of ejectors is desired if any. In this experimental study, we proposed a new type ejector manufactured from the commercial fitting materials and the welding process, which is equipped with an orifice type nozzle. The proposed ejector has a good integrity compared with the conventional ejector because the fittings have manufactured by forging and they have more strength than the casting materials. Furthermore we adopted a multi-opening orifice type nozzle for improving a suction capacity and compared with a single-opening orifice type nozzle. From the experimental results. we confirmed that the multi-opening nozzle had a food suction capacity than the single-opening nozzle and the proposed new type ejector showed higher vacuum than the conventional type ejector in non-load condition. These improved characteristics suggests that a new type ejector by using the commercial fittings opens the feasibility to be adopted in various industry fields and that the increased suction capacity can be achieved by altering the nozzle design of a conventional ejector.

• 한국표면공학회지
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• 제43권5호
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• pp.230-237
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• 2010

FTMP(friction thermo-mechanical process) is an adaptation of friction stir welding, and can be used as a generic process to modify the microstructure at selective locations. In this study, in order to analyze characteristics of surface modification of ACA4 castings by FTMP, change of rotating speed(R/S) and traveling speed(T/S) of tool were applied as conditional parameter. Analysis of microstructure, hardness, surface roughness and depth of modified zone(MZ) were searched. The best condition were obtained at R/S 600 rpm and T/S 100 mm/min. At this time, hardness was 82 HV, the surface roughness was 0.07 mm and the depth at MZ was 1.72 mm. Free defects microstructure and fine Si particles formation and strong forging effects were analyzed at MZ.

• 융합경영연구
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• 제9권4호
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• pp.9-18
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• 2021

Purpose: This study examines some successful and failed cases of Korean private universities' profitable business and explores the desirable economic value and direction of their profitable business business operations with a view to shedding light on some clues conducive to their financial health and quality education. Research design, data and methodology: This study reviews news articles, reports and literature to find out Korean universities' financial condition and examines some successful and failed examples of their corporations' profit-making business operations to suggest a direction. Results: Private universities suffer declining enrollments and/or tuition freeze but they lack in making efforts to secure financial health. The reviewed examples of private universities' profit-making business operations suggest both universities and their corporations should first assume the public accountability prior to engaging in diverse business activities. Conclusions: First, to remain financially healthy, university corporations should exert themselves to transform their low-profit-margin lands and buildings into high-profit-margin businesses and to credit the realized income to their school-expense accounts. And, the ultimate purpose of universities' profit-making business operations is to realize a decent income without prejudice to their public accountability for the country and community, while forging a virtuous cycle by investing the income for the betterment of their educational quality and competitiveness.

• 한국기계가공학회지
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• 제19권9호
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• pp.100-106
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• 2020

This study analyzes the residual stress of AISI 1536V for an engine shaft of the shipbuilding industry and AISI A387 for a reactor shell of the chemical refining industry by the hole drilling method with a strain gauge rosette, which transforms fine mechanical changes into electrical signals. Tensile residual stress is generated in the forging and heat treatment process because specimens are affected by thermal stress and metal transformation stress. In the heat treatment process, the residual stress of AISI A387 is almost 170% the yield strength at 402 MPa. Since during the machining process, variable physical loads are applied to the material, compressive residual stress is generated. Under the same condition, the mechanical properties greatly affect the residual stress during the machining process. After the stress-relieving heat treatment process, the residual stress of AISI A387 is reduced below the yield strength at 182 MPa. Therefore, it is necessary to control the temperature, avoid rapid heat change, and select machining conditions depending on the mechanical properties of materials during manufacturing processes. In addition, to sufficiently reduce the residual stress, it is necessary to study the optimum condition of the stress-relieving heat treatment process for each material.

• 대한기계학회논문집A
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• 제34권1호
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• pp.85-90
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• 2010

자동차 후진기어용 축재는 단조재로서 그 형상은 복잡하고 열처리 및 가공공정이 어려울 뿐 아니라, 제품수명 저하 등의 문제점으로 인한 경제적 손실이 크다. 따라서 종전의 일체형 단조품을 캠 형상 부분만을 기존의 단조품(SF 45)으로 사용하고, 나머지 축 부분은 일반 기계구조용 탄소강재(SM 45C)로 대체를 위한 이종마찰용접을 적용하였다. 마찰용접 변수인 회전수, 마찰압력, 업셋압력, 가열시간, 업셋시간 등의 상호작용에 의한 용접품질과의 상관관계를 고찰하였으며, 최적조건에서 마찰용접을 한 후 용접재(as-welded)와 고주파 열처리를 시행한 후열처리재(PWHT)의 접합부 특성을 비교 고찰하였다. 이는 종전의 일체형 단조품에 비해 단조비용 절감, 피로수명향상, 기계가공에 따른 공정수 및 재료절감 등의 경제적 파급효과가 클 것으로 기대된다.

• 비파괴검사학회지
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• 제35권5호
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• pp.358-366
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• 2015

본 논문에서는 자주포, 전차 및 장갑차 등 지상궤도전투장비에 적용되는 비파괴검사 방안 검토 및 설계방안에 대해서 연구하였다. 비파괴검사 방안 중에서 지상궤도전투장비 비파괴검사자의 기량검증 요건은 미군규격에서 최초로 언급 되었으며, 이후 국내 지상궤도전투장비 무기 개발시 국방규격에도 적용되었다. 그러나 민 군 규격통일화사업을 통해 방산용 비파괴검사자의 자격은 기존 항공분야에서 적용중이던 NAS410이 항공/방산 공용규격으로 통합화 되었다. 본 연구에 대한 설계방안의 검증은 자주포에 사용되는 Al 단조품에 대해 최적설계된 액체침투탐상검사 방법을 적용하여 제품의 신뢰성 및 건전성을 확인하였다.

• Journal of Computational Design and Engineering
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• 제1권1호
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• pp.27-36
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• 2014

Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors affecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteristics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufacturability (and its limitation in logarithmic spiral bevel gears) is analyzed using precision forging and multiaxis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multiaxis freeform milling also need to be solved in a further study.