• Journal of Biosystems Engineering
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• 제36권2호
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• pp.79-88
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• 2011

The purpose of this study was to analyze power requirement of an agricultural tractor by major field operations. First a survey was conducted to obtain annual usage ratio of agricultural tractor by field operation. Plowing, rotary tillage, and loader operations were selected as major field operations of agricultural tractor. Second, a power measurement system was constructed with strain-gauge sensors to measure torque of four driving axles and a PTO axle, speed sensors to measure rotational speed of the driving axles and an engine shaft, pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to calculate power requirement. Third, the major field operations were experimented under fields with different soil conditions following planned operation paths. Power requirement was analyzed during the total operation period consisted of actual operation period (plowing, rotary tillage, and loader operations) and period before and after the actual operation (3-point hitch operating, forward and reverse driving, braking, and steering). Power requirement of tractor major components such as driving axle part, PTO part, main hydraulic part, and auxiliary hydraulic part were measured and calculated to determine usage ratio of agricultural tractor power. Results of averaged power requirement for actual field operation and total operation were 23.1 and 17.5 kW, 24.6 and 19.1 kW, and 14.9 and 8.9 kW, respectively, for plowing, rotary tillage, and loader operations. The results showed that rotary tillage required the greatest power among the operations. Averaged power requirement of driving axles, PTO axle, main hydraulic part, and auxiliary part during the actual field operation were 8.1, 7.8, 3.4, and 1.5 kW, respectively, and the total requirement power was about 70 % (20.8 kW) of the rated power. Averaged power requirement of driving axles, PTO axle, main hydraulic, and auxiliary hydraulic for the total operation period were 6.5, 6.0, 2.1, 0.9 kW, respectively, and total requirement power was about 52 % (15.5 kW) of the rated power. Driving axles required the greatest amount of power among the components.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.157-161
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• 2004

Urban transit is system that offer target Performance and function because various lower part system such as vehicles, signaling, power supply, rail track is consisted as complex. It is important first of all that describe correctly system requirement until configuration of system, design, manufacture, installation and test verification so that the complicated urban transit system is to act safety and reliable and to display target Performance and function properly. The system requirement assist the system developer to comprehensive the performance and function of system in basic design. Therefore, In this paper wishes to study way to analyze system of system requirement and apply to Urban transit.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.67-76
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• 2010

RAM(Reliability, Availability, Maintainability) characteristics of weapon system is a part of Required Operational Capability, must be reasonable and achievable. In this study, we studied the criteria, important factors to establish RAM requirement and reviewed the current process. Then we propose the new process and method to establish the reasonable and achievable RAM requirement by BCS(Baseline Comparison System) model.

• 항공우주시스템공학회지
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• 제7권2호
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• pp.42-46
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• 2013

In 2010, Airworthiness standard for VLA(Very Light Airplane) category was newly introduced as KAS Part VLA. KAS Part VLA is an adaption of EASA CS-VLA which was developed to reduce unnecessary burden of manufacturer of very light, simple, single-reciprocating-engine/propeller powered airplanes having low stall speeds by tailoring some requirements of Part 23. In this paper, difference and similarity of structural requirements between Part 23 and VLA was analyzed.

• 농업과학연구
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• 제31권1호
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• pp.26-34
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• 2004

In this study, motion characteristics and power requirement of rotary tilling according to shape of conventional rotary blade were measured. This study was performed to establish factors which needed to develop energy saving rotary blade. Starting point of edged curve of imported rotary blade was faster than that of domestic rotary blade after measuring and analyzing edged curve of rotary blade. So domestic rotary blade tills much soil than imported rotary blade. In analyzing motion of rotary blade, Rotary blade of A, D type was begun to contact at part 3. Analyzing back surface of rotary blade which contact to soil at critical $\lambda$ results in contacting at e-f part. In measuring power requirement of rotary blade, specific torque and specific work of rotary blade are $160{\sim}170kgf{\cdot}m/m^2$, $3,700kgf{\cdot}m/m^3$. It shows power requirement of rotary blade according to shape of rotary blade are very different.

• 정보처리학회논문지D
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• 제15D권5호
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• pp.647-658
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• 2008

자연어로 작성된 고객의 요구사항은 개발과정에서 모델링 언어로 재작성 된다. 그러나 개발에 참여하는 다양한 계층의 사람들은 모델링 언어로 작성된 요구사항을 이해하지 못하는 경우가 많이 발생한다. 본 논문에서는 REED(REquirement EDitor)로 작성된 요구사항 모델을 자연어로 번역하여 개발에 참여하는 모든 계층의 사람들이 요구사항 모델을 이해할 수 있도록 도와주는 방안을 제시한다. 제시한 방법은 3단계로 구성되어 있다. 1단계 IORT(Input-Output Relation Tree) 생성, 2단계 RTT(Requirement Translation Tree) 생성, 3단계 자연어로 번역의 단계를 거친다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.382-387
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• 2009

Requirement management is an important phase that has a significant influence on the project success. As a risk to a project fail is getting bigger, people adopt Systems Engineering method to the development of the effective requirement management. Accordingly, Railroad Safety Technology R&D Corps. is progressing the plan of the construction of Railway Safety Test Facilities as a part of the Railway Total Safety Project to enhance the railway safety, and carrying out researches on effective requirement management methods with Systems Engineering techniques. To support that, we introduce the Systems Engineering Requirement Management Process and propose the more effectual management method of constructing the Railway Safety Test Facilities applying the model-based systems engineering tool to the research.

• 시스템엔지니어링학술지
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• 제3권1호
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• pp.33-40
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• 2007

The requirement verification is the integral part of the weapon system R&D to reduce cost and schedule. And, a systems engineering is an interdisciplinary engineering management process that evolves and verifies an integrated, life-cycle balanced set of system solutions that satisfy customer needs. Therefore, this study analyzes the national defense need and acquisition management process, investigates the systems engineering verification activity. Through the requirement verification example in terms of technical evaluation this study presented the requirement verification approach in the weapon system R&D.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2010년도 한국우주과학회보 제19권1호
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• pp.25.3-25.3
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• 2010

Our previous study used a bar-type reference mirror to measure the relative distance to the target surface. The target measurement accuracy was required to $1{\mu}m$ PV for aspheric optical surface up to 1m in diameter. Earlier system suffers from the reference surface deformation when the measuring part moves. In order to reduce the deformation, measuring part and the reference part separated from each order in the new design. This system utilizes a kinematic support assembly using invar flexure to minimize the reference surface deformation under gravity and vibration. The surface deformation requirement of reference mirror is defined as of $0.2{\mu}m$ under gravity and 40Hz vibration. The finite element results, shows reference mirror deformation of $0.164{\mu}m$. The first resonance mode was computed to analysis 46.05Hz for reference part and 43.44Hz for measuring part. Thesis satisfies the frequency requirement.

• 정보처리학회논문지D
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• 제14D권6호
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• pp.641-648
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• 2007

요구사항이 빈번히 변경되는 동적 비즈니스 시스템 프로젝트를 확정가로 개발할 경우, 개발과정에서 발생하는 요구사항의 변경에 따른 추가 소요 비용으로 인해 확정가 범위 이내로 개발을 완료하는 것은 거의 불가능하다. 확정가 범위 이내에서 성공적으로 프로젝트를 완료하기 위해서는 요구사항 변경 규모와 이에 기반하여 개발이 되지 않아도 되는 옵션 요구사항의 비율을 관리하여야 한다. 이에 대해 Bhagwat는 요구사항 변경이 구축단계에서만 발생한다고 한정하였다. 또한, 소프트웨어 개발비용, 구축단계 소요 비용과 요구사항 변경에 소요되는 추가 비용이 동일하다고 가정함으로써 요구사항 변경 비율과 옵션 요구사항의 비율 유도의 모순을 보였다. 본 논문은 요구사항 변경은 정련단계와 구축단계에서 발생한다고 가정하였다. 또한, 소프트웨어 개발비용, 구축단계 소요 비용과 요구사항 변경 비용간에는 차이가 발생한다고 가정하였다. 그 결과 확정가 대비 요구사항 변경에 따른 추가 소요 비용과 개발이 되지 않아도 되는 옵션 요구사항의 비율도 보다 현실성을 반영하는 결과를 얻을 수 있었다.