• 한국산학기술학회논문지
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• 제19권1호
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• pp.34-47
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• 2018

융합기술 개발에 대한 선진국들의 관심이 고조되는 가운데 우리나라의 융합기술 분야의 경쟁력 강화를 위한 전략적 기술개발의 접근으로, 기술 및 산업분야에 미치는 후생적 파급효과가 큰 핵심융합기술을 발굴할 수 있는 방법론이 요구된다. 본 연구에서는 특허의 기술융합수준을 후생적으로 타기술분야들을 연계하는 파급효과 수준으로 정의하고, 스마트공장의 ICT 융합기술 분야 1,124개 미국출원특허를 이용한 특허 인용 네트워크 분석을 통하여, IPC 기술분야 네트워크로부터 산출한 IPC 기술분야 매개중심성 지수를 이용하여 해당 특허의 기술융합수준을 측정하는 이종분야 기술융합지수를 소개하였다. 본 연구에서 제안한 이종분야 기술융합지수와 중재자역할 지표와의 상관관계를 분석한 결과, 다른 지수들 (타분야비율지수 및 동종분야 기술융합지수) 대비 이종분야 기술융합지수가 후생적으로 다른 기술분야들을 연계하는 파급효과 차원의 융합특성을 측정하는 지수임이 확인되었다. 제안한 이종분야 기술융합지수를 이용하여 정부부처에서 제시한 스마트공장의 주요 ICT기술 전략분야들 중 핵심 ICT 융합기술분야들을 분석한 결과, '제조실행분석 애플리케이션'을 포함한 6개의 핵심 ICT융합 기술분야들을 도출하였다. 추가로 '제조실행분석 애플리케이션'에 속한 특허들의 IPC들을 대상으로 블록모델링 분석한 결과, '전자통신기술'과 '전자 디지털데이터 처리기술'로 대표되는 블록들(블록 3&4)이 핵심기술과 융합 가능한 관련 기술분야임을 확인하였다. 본 연구의 결과에 근거하여 스마트공장의 융합기술 개발방안에 대한 정책적 시사점을 제공하였다.

• 한국가스학회지
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• 제25권2호
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• pp.22-27
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• 2021

이 논문은 LPG 자동차용 엔진의 고장사례를 연구하여 자동차 생산에 활용함이 목적이다. 첫번째 사례는 엔진의 실린더헤드를 분해하여 확인한 결과 실린더 헤드의 점화플러그가 조립되는 나사부 마멸때문에 점화플러그의 불꽃이 누설되어 출력이 떨어지면서 엔진의 부조화 현상이 가끔 유발되는 것을 발견하였다.. 두 번째 사례는 캠샤프트의 위치와 크랭크 샤프트 위치를 맞춘 타이밍 마크가 0.5칸 틀어져 엔진의 부조화 현상이 발생된 것을 확인되었다. 세 번째 사례는 실린더 헤드를 분해하여 확인한 결과, 실린더 헤드에 제거되지 못한 이물질이 3번 흡기포트에서 공기 흐름에 따라 이동하다가 흡기밸브의 닫힘시기를 원활하지 못하여 하여 고장이 발생된 것을 확인하였다. 따라서, 자동차 관리자는 철저하게 점검해야 하고, 자동차 생산자는 철저한 품질확보를 통해 고장의 원인을 제거해야 할 것으로 판단된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1386-1391
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• 2004

It is known that an aircraft with delta-wings which are attached to the body at a large angle like a kite or a hang glider has a measure of maneuverability and stability. Aircrafts of this kind can fly stably. Even if engine trouble occurs, it will not fall and might be able to land. In this paper, one of the conventional control methods, PID control, is applied to the aircraft with LQ local control block. This is based on an idea that the aircraft flies so stably that the automatic control system might be realized by a simple controller. The proposed PID controller consists of several sub-controllers which are constructed to each system neglecting the interference. In addition, the LQ control is involved as a local loop of the aileron and rudder control in order to increase stability of the attitude when circling. The effectiveness of the proposed method is shown through 3D computer simulations and experiments of the flight path control.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.285-288
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• 2001

Hypereutectic Al-25Si-X alloys, expected to be applied to the cylinder-liner-part of the engine-block of an automobile due to the excellent wear resistance, low density and low thermal expansion coefficient has been fabricated through a spray forming process. The obtained microstructure of the hypereutectic Al-25Si-X alloy appeared to consist of Al matrix and equiaxed Si particles of average diameter of $5-7{\mu}m$. To characterize the deformation behavior of this alloy, a series of load relaxation and compression tests have been conducted at temperatures ranging from RT to $500^{\circ}C$. The strain rate sensitivity parameter (m) of this alloy has been found to be very low (0.1) below foot and reached 0.2 at $500^{\circ}C$. During the deformation above 300'c in compression, strain softening has been observed. The diagram of extrusion pressure vs. ram-speed has been constructed, providing the extrusion condition of Al-25Si-X alloys.

• 천문학회보
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• 제40권2호
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• pp.37.2-38
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• 2015

According to the unified model of AGNs, type 1 and 2 AGNs are intrinsically the same objects but seem different due to an obscuring matter which can block lights from the central engine of the AGN depending on the viewing angle. The obscuring object is thought to be shaped in a toroidal form and thus the geometry of tori of AGNs is an important factor to determine the fraction of type 1 (or type 2) AGNs. Oh et al. (2015) provides a new catalog of type 1 AGNs from SDSS DR7 in the nearby universe (z < 0.2) and it contains nearly 50% more type 1 AGNs than previously known. Using this new catalog, we test the fraction of type 1 AGNs along the black hole mass (MBH) and the bolometric luminosity of AGNs (Lbol), which are regarded as key parameters of the AGNs. First of all, because the methods to derive the black hole mass and the bolometric luminosity bear uncertainties, we test how the different methods lead to different values of type 1 fraction. We found that the fraction of type 1 AGNs varies with both MBH and Lbol. The extensively-studied, "receding torus model" can only explain the trend along Lbol and hence fails to explain the trend. To understand the new trend, we test the geometry of the torus based on the "clumpy torus model". We present our results on the basic properties of the torus such as a column density or opening angle and compare with those from previous studies based on other wavelengths (e.g. Infrared or X-ray).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1299-1302
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• 2004

A real object duplication system (RODS), including three dimensional (3D) scanner and solid freeform fabrication system (SFFS), is a device to make three-dimensional objects directly from the drawing or photo data. A Selective Multi-Laser Sintering (SMLS) process designed in this paper is by which computer images received using 3D scanner are built up from polymer powder on building room of large size using dual laser at industrial type SFF system. Using the process can rapidly produce real object duplication components of industrial type such as cylinder, engine block, chassis of automobile, etc. In this paper, the industrial type SFF system using SMLS process is manufactured and the system is satisfied with high precision and high speed processing technique. To research characteristics of each part for theindustrial type SFF system, a structure and thermal analysis and test of each part is carried out. Also, to achievement of high performance for industrial type SFF system, design and fabrication for the structure, heater, nitrogen supply, laser and control part are carried out.

• Tribology and Lubricants
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• 제23권4호
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• pp.170-174
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• 2007

Wear and scuffing tests were conducted using friction and wear measurement of piston rings and cylinder blocks in low friction diesel engine. The frictional forces, wear amounts and cycles to scuffing in boundary lubricated sliding condition were measured using the reciprocating wear tester. The cylinder blocks were used as reciprocating specimens, and the piston rings with several coatings were used as fixed pin. Several coatings were used such as DLC, TiN, Cr-ceramic and TiAlN in order to improve the tribological characteristics. From the tests wear volume of piston ring surfaces applied various coatings were compared. During the tests coefficients of friction were monitored. Test results showed that DLC coatings showed good tribological properties. TiN and Cr-ceramic coated rings showed good wear resistance properties but produced high friction.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.20-23
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• 2001

Hypereutectic Al-25Si alloy, which is expected to be applied to the cylinder-liner-part of the engine-block of an automobile due to its excellent wear resistance, low density and low thermal expansion coefficient, has been fabricated through a spray forming process. The obtained microstructure of the hypereutectic Al-25Si alloy appeared to consist of Al matrix and equiaxed Si particles of average diameter of 5-7 mm. To characterize the deformation behavior of this alloy, a series of load relaxation and compression tests have been conducted at temperatures ranging from RT to $500^{\circ}C$. The strain rate sensitivity parameter (m) of this alloy has been found to be very low (0.1) below $400^{\circ}C$ and reached maximum value of about 0.2 at $500^{\circ}C$. During the deformation above $300^{\circ}C$ in compression, strain softening has been observed. The diagram of extrusion pressure vs. ram-speed has been constructed. The extrusion has been successfully conducted at the temperatures of $300^{\circ}C$ and above with the ratio of area reduction of 28 and 40 in this study.

• 한국추진공학회지
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• 제11권4호
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• pp.59-66
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• 2007

부분분사비에 따른 초음속 충동형 터빈 성능변화에 대하여 실험적 연구를 수행하였다. 실험은 개방형액체로켓 엔진의 터보펌프에 사용되는 터빈을 이용하였으며 부분분사비 조절을 위해 실험용 노즐블럭을 설계/제작하였다. 실험에 사용된 터빈은 축대칭 수축-확산형 노즐을 갖고 있으며 작동노즐의 개수조절을 통해 부분분사비를 변화시켰다. 작동유체는 고압공기를 사용하였다. 실험결과 초음속 충동형 축류터빈은 부분분사비 변화에 따른 성능변화가 크지 않은 것으로 나타났다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.407-410
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• 1998

Configuration is a set of building block processes, a series of selection and combining parts or components which composes a whole thing. A whole thing could be such a configurable object as manufacturing product, network system, financial portfolio, system development plan, project team, etc. Configuration problem could happen during any phase of product life cycle: design, production, sales, installation, and maintenance. Configuration has long been one of cost and time consuming work, because only high salaried technical experts on product and components can do configuration. Rework for error adjustments of configurations at later process causes far much cost and time, so accurate configuration is required. Under the on-line electronic commerce environment, configuration problem solving becomes more important, because component-based sales should be done automatically on the merchant web site. Automated product search, order placement, order fulfillment and payment make that manual configuration is no longer feasible. Automated configuration means that all the constraints among components should be checked and confirmed by configuration engine automatically. In addition, technical constraints and customer preferences like price range and a specific function required should be considered. This paper gives an brief overview of configuration problems: characteristics, representation paradigms, and solving algorithms and introduce CRSP(Constraint and Rule Satisfaction Problem) method. CRSP method adopts both constraint and rule for configuration domain knowledge representation. A survey and analysis on web sites adopting configuration functions are provided. Future directions of configuration for EC is discussed in the three aspects: methodology itself, companies adopting configuration function, and electronic commerce industry.