• STI Policy Review
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• 제4권1호
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• pp.74-93
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• 2013

Although open innovation (OI) has been an important research theme for over a decade, its theoretical framework has been relatively under-researched. As OI involves a wide range of innovation activities, a firm's capacities in the use of the various firm resources play a critical role in OI implementation. However, it is unclear how they affect firms' performances for little is known of OI capacities. Based on a theoretical framework derived from the literature, this study looks into the relationships between six OI capacities (inventive, absorptive, transformative, connective, innovative, and desorptive) and financial performance using the Korean Innovation Survey (KIS) 2008 data. The research model was tested using structural equation modelling (SEM) while potential differences in capacities between different firm groups were also investigated. The results indicate that 1) OI capacities are significantly associated with firms' financial performance; 2) capacities are highly correlated with one another; and 3) some capacities are differently configured between different types of firms. Findings suggest that policy makers should pay more attention to helping firms enhance OI capacities and attempt to develop relevant policies in order to complement inadequate capacities.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.328-333
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• 2007

The purpose of this study is modelling of system air-conditioner for TRNSYS. System air-conditioner is operated by a variable capacity compressor and accommodated by multiple evaporators. By reason of these feature, realizing performance of system air-conditioner for TRNSYS was incomplete. In this study performance data of system air-conditioner and control logics are used to make system air-conditioner module for TRNSYS. Performance data contains total capacity, power input and capacity index of system air-conditioner. The simulation was carried out in a mode of temperature level control using TRNSYS 16. The simulation shows that the system air-conditioner model operate variable capacity and can compute capacity index and power input of system.

• 전기학회논문지P
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• 제52권2호
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• pp.74-80
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• 2003

In this paper, a robust two-degree-of-freedom(TDF) the speed control system using $H_{\infty}$ optimization method and real genetic algorithm is proposed for the robust stability and the robust performance in dc servo motor system. This control system composed of feedback and feedforward controller. The feedback(FB) controller with $H_{\infty}$ optimization method is designed for real genetic algorithm that is model matching problem using mixed sensitivity function. The feedforward(FF) controller with $H_{\infty}$optimization method is minimized the error between transfer function of the optimal model and the overall transfer function. The proposed robust two-degree-of-freedom speed control system is simulated to the dc servo motor. By the simulation, feedback controller can obtain the robust stability property and feedforward controller can obtain the robust performance property under modelling error. The performance of the dc servo motor is analyzed by the experiment setting. The validity of the proposed method is verified through being compared with pid(proportional integrated differential)control system design method for the dc servo motor.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.263-267
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• 2008

본 연구에서는 헬리콥터 추진시스템의 장착 성능해석 모델링 시 고려하여야 할 흡입구 모델, 블리드 공기 손실, 보기류 시스템 구동에 사용되는 출력 추출 등을 포함한 장착 성능해석을 수행하였다. 흡입구의 압력 손실은 비행마하수와 유량에 따른 압력손실 값으로 나타낸 흡입구 성능 맵을 이용하였다. 추진시스템 장착 성능해석 모델링의 검증을 위해서는 실제 시험데이터와 비교해야 하지만 데이터 확보가 어려워 상용성능해석 프로그램인 GASTURB 해석결과와 비교 하였다. 해석결과 평균오차 0.5% 이내로 본 연구에서 수행한 추진시스템의 장착 성능해석 모델링의 타당성을 검증하였다.

• 한국추진공학회지
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• 제12권1호
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• pp.51-56
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• 2008

본 연구에서는 헬리콥터 추진시스템의 장착 성능해석 모델링 시 고려하여야 할 흡입구 모델, 블리드 공기 손실, 보기류 시스템 구동에 사용되는 출력 추출 등을 포함한 장착 성능해석을 수행하였다. 흡입구의 압력 손실은 비행마하수와 유량에 따른 압력손실 값으로 나타낸 흡입구 성능 맵을 이용하였다. 추진시스템 장착 성능해석 모델링의 검증을 위해서는 실제 시험데이터와 비교해야 하지만 데이터 확보가 어려워 상용성능해석 프로그램인 GASTURB 해석결과와 비교하였다. 해석결과 평균오차 0.5% 이내로 본 연구에서 수행한 추진시스템의 장착 성능해석 모델링의 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.120-123
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• 2005

This paper, for the establishment of power system models and test procedures for the dynamic performance test of transformer protective relay, presents power system model, environment establishement between RTDS and protective relay, and the dynamic performance test generated internal fault or external fault.

• 한국해안·해양공학회논문집
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• 제32권5호
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• pp.340-350
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• 2020

한반도 대기모델의 해상풍을 입력자료로 사용하는 초단기 파랑예측시스템을 구축하고, 예측성능을 결정하는 중요한 요소인 입력바람장-파랑 상호작용을 고려하여, 수치모의실험을 수행하였다. 예측성능을 검증하기 위해 비태풍시기와 태풍시기에 대한 파랑모델의 예측결과를 기상청 계류부이 관측자료와 비교하였다. 비태풍시기에는 전반적으로 모델의 과소모의 경향이 나타났으며, 입력바람장과 파랑의 상호작용 물리계수를 증가시키면 과소모의하는 예측경향과 평균제곱근오차(RMSE)는 감소하는 것을 확인할 수 있었다. RMSE가 최소가 되는 실험조건을 적용하여 태풍시기를 분석한 결과, 비태풍시기와 비교하여 예측오차가 증가하였다. 이는 파랑모델이 상대적으로 약한 비태풍시기의 바람장 영향을 고려했기 때문으로 보이며, 강한 바람장 형성으로 인한 파랑의 비선형효과와 파랑에너지 소산효과가 충분히 반영되지 않았던 것으로 판단된다.

• Journal of Computing Science and Engineering
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• 제8권3호
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• pp.129-136
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• 2014

This paper presents the equivalent circuit modelling and eigenfrequency analysis of a wideband robust capacitive radio frequency (RF) microelectromechanical system (MEMS) switch that was designed using Poly-Si and Au layer membrane for highly reliable switching operation. The circuit characterization includes the extraction of resistance, inductance, on and off state capacitance, and Q-factor. The first six eigenfrequencies are analyzed using a finite element modeler, and the equivalent modes are demonstrated. The switch is optimized for millimeter wave frequencies, which indicate excellent RF performance with isolation of more than 55 dB and a low insertion loss of 0.1 dB in the V-band. The designed switch actuates at 13.2 V. The R, L, C and Q-factor are simulated using Y-matrix data over a frequency sweep of 20-100 GHz. The proposed switch has various applications in satellite communication networks and can also be used for devices that will incorporate the upcoming IEEE Wi-Fi 802.11ad protocol.

• Structural Engineering and Mechanics
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• 제38권1호
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• pp.27-37
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• 2011

This paper presents the results of a study on the capability of nonlinear quasi-static finite element modelling in simulating the hysteretic behaviour of CFRP and GFRP-retrofitted RC exterior beam-column joints under cyclic loads. Four specimens including two plain and two CFRP/GFRP-strengthened beam-column joints tested by Mahini and Ronagh (2004) and other researchers are modelled using ANSYS. Concrete in compression is defined by the modified Hognestad model and anisotropic multi-linear model is employed for modelling the stress-strain relations in reinforcing bars while anisotropic plasticity is considered for the FRP composite. Both concrete and FRP are modelled using solid elements whereas space link elements are used for steel bars considering a perfect bond between materials. A step by step load increment procedure to simulate the cyclic loading regime employed in the testing. An automatically reforming stiffness matrix strategy is used in order to simulate the actual seismic performance of the RC concrete after cracking, steel yielding and concrete crushing during the push and pull loading cycles. The results show that the hysteretic simulation for all specimens is satisfactory and therefore suggest that the numerical model can be used as an inexpensive tool to design of FRP-strengthened RC beam-column joints under cyclic loads.

• Nuclear Engineering and Technology
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• 제41권1호
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• pp.1-10
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• 2009

The safe and reliable performance of fusion and fission plants depends on the choice of suitable materials and an assessment of long-term materials degradation. These materials are degraded by their exposure to extreme conditions; it is necessary, therefore, to address the issue of long-term damage evolution of materials under service exposure in advanced plants. The empirical approach to the study of structural materials and fuels is reaching its limit when used to define and extrapolate new materials, new environments, or new operating conditions due to a lack of knowledge of the basic principles and mechanisms present. Materials designed for future Gen IV systems require significant innovation for the new environments that the materials will be exposed to. Thus, it is a challenge to understand the materials more precisely and to go far beyond the current empirical design methodology. Breakthrough technology is being achieved with the incorporation in design codes of a fundamental understanding of the properties of materials. This paper discusses the multi-scale, multi-code computations and multi-dimensional modelling undertaken to understand the mechanical properties of these materials. Such an approach is envisaged to probe beyond currently possible approaches to become a predictive tool in estimating the mechanical properties and lifetimes of materials.