• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.573-577
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• 2009

Dynamic behavior simulation of supersonic engine was performed and PI control algorithm was studied for the buzz control in the inlet and the thrust control. Firstly, required thrust was tracked according to the fuel flow control and then inlet pressure was regulated through the nozzle throat area control so that the buzz margin has the positive all the time. The control was performed according to the change of flight Mach number, altitude and angle of attack. The proportional gain and the integral gain for regulating the buzz margin was induced and simulated. In the results, it was confirmed and satisfied that control target in the operating area was changed the angle of attack from $0^{\circ}$ to $10^{\circ}$ at the flight Mach number of 2.1~3.0.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.89-98
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• 2006

This paper describes signal attenuation characteristics as splicing the output on LVDT for stability and reliability of switching mechanism, which is developed to use common signal between FLCC and EDFLCC, on T-50 aircraft. The method of test is classified a Pspice simulation and an actual hardware evaluation. The difference of error margin for two methods is 10times, the latter higher. The result in this experiment shows that the signal attenuation as splicing the output on LVDT doesn't affect and the static error margin is 53% for develope the EDFLCC.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.05a
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• pp.64-67
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• 2002

인터넷 기반의 전자상거래에 참여하는 판매자와 구매자는 가격, 마진 등 다양한 거래조건들을 가지고 협상 (negotiation)을 진행하는 경우가 많다. 그러나, 기존연구에서는 대부분 가격과 거래량과 같은 두 개 미만의 정량적 (quantitative)인 거래조건을 중심으로 협상을 진행하는 방안을 중점적으로 다루었다. 그 결과, 단순한 실험적 문제에 대해서만 협상지원이 가능했고, 실세계의 전자상거래 협상과정에서 발생할 수 있는 다중 협상 요인들간의 동적인 변화를 고려하지 못했다는 지적을 피하기 어렵다. 본 연구에서는 이러한 점에 주목하여 전자상거래 판매자와 구매자가 웹 상에서 다차원적인 거래조건을 가지고 실시간으로 시뮬레이션을 하면서 보다 동적으로 협상을 수행할 수 있도록 퍼지 멤버심 함수와 AHP 추론기법을 이용한 전자상거래 협상지원 (Fuzzy AHP Negotiation support. FAHP-NEGO) 메커니즘을 제안하고자 한다. 실험결과, 협상에 필요한 정량적인 값과 판매자와 구매자의 주관적인 의사결정 행동양식이 반영된 보다 동적인 협상을 진행할 수 있었다. 따라서, 본 연구결과는 향후, 전자상거래 협상에 있어서 보다 현실적인 협상을 지원할 수 있을 것으로 기대한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.28-28
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• 2002

가스터빈 엔진을 운용하는 데 있어서 가/감속율을 크게 하면 엔진성능 천이 시간은 짧으나 압축기에서의 서지나 터빈 입구온도의 급격한 상승이 발생할 수 있으며 가/감속율을 작게 하면 엔진은 안정적이나 천이시간이 길어지게 되어 결과적으로 엔진의 동적 응답성이 나빠지게 된다. 또한 압축기에서 발생할 수 있는 서지를 방지하기 위하여 압축기 서지 마진이 l0%∼20%인 서지 한계선(조정선)을 설정하여 엔진이 서지 한계선을 넘지 않도록 제어한다.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.37-37
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• 2003

목적 : 일반적으로 세기조절방사선치료 조사면의 작은 조각 크기에 대해, 이상적인 플루언스 지도 혹은 치료계획장치로부터의 최적화된 결과에 가까운 선량분포에서 더 좋은 leaf sequence를 얻을 수 있다. 한편, 치료중 장기의 움직임이 가장 작은 조각 크기의 선택을 방해하는 문제는 항상 존재한다. 게다가, 전통적인 정지 조사면과 달리 표적이 움직이는 동안 조사면 자체도 움직이므로 움직이는 표적에 대한 세기조절방사선치료의 경우에서 적절한 표적 마진에 관한 질문이 제기되어왔다. 따라서, 이 연구에서는 조각 크기에 대한 치료중 표적 움직임의 효과를 연구하였다. 대상 및 방법 : 세기조절방사선치료 플루언스 지도에 대해, 다양한 크기 - 0.5$\times$0.5, 1.0$\times$1.0, $1.5\times$1.5, 2.0$\times$2.0, 3.0$\times$3.0, 4.0$\times$4.0, 5.0$\times$5.0 $ extrm{cm}^2$ - 의 정사각형 패턴들을 설계하였고, Leaf sequence 는 step-and-shoot 빔 전달 방법을 이용하였다. 인접 조각들 사이의 세기 비율은 0.2, 0.4, 0.6, 0.8, 1.0로 하였고, 표적 움직임은 범위가 0.5-2.0 cm인 사인곡선 형태로 가정하였다. 움직임 묘사를 위해 동적 leaf 의 움직임이 표적의 움직임 을 반영하도록 계산되었고 움직임의 효과를 분석하기 위해 필름선량측정을 수행하였다. 결과 : 인접 조각의 세기 비율은 모든 경우에서 저하되었고, 호흡 진폭의 반보다 작은 조각 크기에 대한 선량분포는 임상적으로 유의할만큼 저하된 세기 지도를 보였다. 조각에 대해 방사선 조사시간의 두 호흡주기이상에 대해서는, 표적 마진 주위의 선량분포가 통상적인 정지 조사면에서와 같았다. 결론 : 플루언스 지도에서 세기조절방사선치료 조각의 최소 크기는 치료중 장기 움직임을 고려한 후 선택되어야 한다. 조각에 대한 방사선 조사시간의 두 호흡주기이상에 대해서는, 표적 마진을 기존의 정지 조사면과 같게 정의할 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.539-546
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• 2013

Surge phenomenon can be occurred in a compressor when compressor performance of turbofan engine for an aircraft is changed considerably in a short time on the cases like take-off phase and changing of RPM from idle to maximum, because performance of aircraft engine is changed suddenly. This study is aimed to avoid surge in a compressor. Dynamic simulation in a compressor is modeled by simulink in specific condition. Fuel flow is control input, rpm and air mass flow are expressed in terms of transfer function. Surge margin is obtained by using compressor performance map from NPSS. VIGV(Variable Inlet Guide Vane) is controlled by PD controller with difference between surge margin and reference. Finally this paper verifies IGV can prevent surge phenomenon in a compressor.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.5
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• pp.653-658
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• 2017

To evaluate the effects of amylose content and dissolution media on the molecular structure of maize starch, changes in the hydrodynamic diameter of starch molecules were assessed via dynamic light scattering depending on amylose content and dissolution media. As the amylose content of starch increased, the hydrodynamic diameter of starch molecules proportionally decreased from 204 to 92 nm. To alter ionic strength, hydrogen bonding, or polarity of dissolution media, various contents of NaCl (1, 2, or 3 M), urea (1, 2, or 3 M), or 1-butanol (0.1, 0.5, or 1.0%) were added to media, respectively, resulting in increased hydrodynamic diameter of starch. However, the degree of expansion was dependent on amylose content and the concentration and/or type of additive. The hydrodynamic diameter of starch molecules exhibited significant correlation with amylose content obtained by size exclusion chromatography, regardless of dissolution conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.27-34
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• 2014

Buzz margin scheduling and control technique which are suitable to regulate stable and high pressure air in wide range of Mach number are suggested for fixed geometry of a supersonic intake. From the analysis of preceding study, most effective control variable is induced and scheduling law is newly suggested in a real application point of view. The appropriateness of the control law in wide range of Mach number is addressed by numerical simulation of controlled propulsion system. Also, the simulation for stabilization and tracking performances of the controller are studied to investigate the phenomena under flight maneuver and disturbances.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.52-61
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• 2015

This paper performed a numerical study to analyse the transient performance behavior of a turbofan engine with variable inlet guide vane (IGV) and bleed air schedules. The low bypass ratio mixed flow turbofan engine was considered in this study. For modeling the compressor performance with IGV, the performance maps were generated by using a one-dimensional meanline analysis and feed to the engine simulation program. The IGV and bleed air according to the rotating speed were scheduled to satisfy 10% of surge margin at steady-state condition. The transient engine performance analysis was conducted with the schedules. The engine with IGV schedule showed a higher surge margin and lower turbine inlet temperature than the engine with bleed air schedule during the transient period.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.13-18
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• 2005

The variation of discharge characteristics of an ac PDP was observed with the charge of scan electrode driving circuit. Conventional scan electrode driving circuit provides two switches per one scan line, and the suggested one can be constituted by one switch per one scan line with the consideration of capacitive load characteristic of an ac PDP. To verify the workability of the suggested scheme, the performances of the ac PDP was investigated. The dynamic voltage margin was slightly decreased with the adoption of the suggested scheme, which is estimated to result from the misfiring of unselected discharge cells due to the deformation of voltage level of the neighboring scan electrode. In the observation of the delay characteristics of addressing discharge, the performances of the conventional circuit and the suggested one are assumed to be equivalent.