• International Commerce and Information Review
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• v.15 no.3
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• pp.3-24
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• 2013

This study has examined the relationship between entrepreneurial orientation(EO), dynamic capability(DC) and export performance of international new ventures(INVs). Also, the moderating effect of external environment factors(the hostility at domestic markets and the industrial dynamics) were analysed. Empirical analysis was performed on 101 INVs. It was conducted using the PLS(Partial Least Square). The result of empirical analysis showed that there is a positive relationship between EO, DC and export performance. The result of moderating effect showed that two external environment factors have positive moderating effect on the relationship between EO and DC. However, there was not moderating effect of external environment factors on the relationship between DC and export performance.

• Journal of KIISE
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• v.41 no.11
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• pp.892-899
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• 2014

Dynamic binary instrumentation is a code insertion technique for debugging a program without scattering its execution flow, while the program is running. Most dynamic instrumentations are implemented using dynamic binary translation techniques. Existing studies translated program codes dynamically by parsing the machine code stream to intermediate representation (IR) and then applying compilation techniques for IRs. However, they have high overhead during translation, which is a major cause of difficulty in applying the dynamic binary translation technique to the program which requires high responsiveness. In this paper, we introduce a light-weight dynamic binary instrumentation framework based on a novel dynamic binary translation technique which has low overhead while translating the program code. In order to reduce the translation overhead, our approach adopts a tabular-based address translation and exploits a translation bypassing scheme, which stores the translated address of a frequently called library function in advance. It then accesses the translated address and executes function codes without code translation when calling the function. Our experiment results demonstrated that the proposed approach outperforms the prior dynamic binary translation techniques from 2% up to 65%.

• Journal of the Korean GEO-environmental Society
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• v.17 no.1
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• pp.5-12
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• 2016

Investigation of in-situ ground in cold region is difficult due to low accessibility and environmental factors. In this study, correlation between dynamic cone resistance and shear strength is suggested to estimate the strength of frozen soils by using instrumented dynamic cone penetrometer. Tests were conducted in freezing chamber after preparing sand-silt mixture with 2.3% water content. Vertical stresses of 5 kPa and 10 kPa were applied during freezing, shearing, and penetration phase to compare the dynamic cone resistance and shear strength. The dynamic cone resistance, additionally, is calculated to minimize the effect of energy loss during hammer impact. Experimental results show that as the shear strength increases, the dynamic cone penetration index (DCPI) decreases nonlinearly, while the dynamic cone resistance increases linearly. This study provides the useful correlation to evaluate strength properties of the frozen soils from the dynamic cone penetration and direct shear tests.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.186-186
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• 2010

개별 블레이드 피치 제어(individual blade pitch control)는 각각의 로터 블레이드의 피치각을 독립적으로 조정함으로써 블레이드에 작용하는 공력을 변화시키는 원리로 풍력 터빈 구조물에 발생하는 동적 피로하중을 저감시키기 위한 제어기법이다. 그러나 개별 피치 제어에 의해 발생하는 각 블레이드의 독립적인 피치 운동은 풍력 터빈 회전자에 비대칭성을 야기하고 구조물의 동적 불안정 현상을 발생시킬 수 있기 때문에 이에 대한 정확한 동적 해석이 선행되어야 한다. 하지만 블레이드의 피치 운동이 반영된 풍력 터빈은 시변계로 간주되어 기존의 시불변계 해석기법을 직접 적용할 수 없기 때문에 동적 해석에 어려움이 있다. 이 논문에서는 각각의 블레이드 피치운동을 주기함수로 근사화 함으로써 풍력 터빈을 주기 시변계로 모형화한다. 그리고 효율적으로 주기 시변계의 근사해를 구하기 위한 변조 좌표 변환(modulated coordinate transformation)기법을 적용하여 블레이드의 피치운동이 반영된 풍력 터빈의 동적 안정성 해석을 수행하였다. 그리고 현재 풍력 터빈의 동적 해석에 활용되는 대표적인 해석 기법인 다중 블레이드 좌표변환(multi-blade coordinate transformation)기법을 이용한 해석보다 정확한 결과를 얻을 수 있음을 보였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.91-97
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• 2002

Dynamic extinction of solid propellants subjected to rapid pressure drop was studied with the aid of energy equation of condensed phase and flame model in gas phase. It is found that the total residence time($\tau_\gamma$) which measures the residing time of fuel in the reaction zone may play a crucial role in determining the dynamic response of the combustuion to extinction. Residence time was modeled by various combinations of diffusion and chemocal kinetic time scale. Effect of pressure history coupled with chamber volume on the extinction response was also performed and was found that dynamic extinction is more susceptible in a confined chamber than in open geometry. And, dynamic extinction was revealed to be affected profoundly by diffysion time scale rather than chemical kinetic time scale.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.743-746
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• 2011

본 연구에서는 유한요소해석을 이용하여 차량속도 및 긴장재의 설계에 따른 CFTA 거더의 동적거동 및 동적증폭계수를 분석하였다. 긴장재의 해석변수로서는 긴장재의 양과 긴장력을 고려하였으며 차량하중은 도로교설계기준의 DB-24 하중을 선택하였다. 차량하중은 3축-2트랙에 작용하는 등가절점하중으로 변환하여 속도에 따라 시간함수로 모델링하였다. 긴장재의 양은 외측 �� 내측 덕트의 유무에 따라 변화시켰으며 긴장력은 설계긴장력의 0%에서 100%까지 25%씩 증가시켰다. 차량속도는 40km/hr에서 100km/hr까지 20km/hr씩 증가시켰으며, 해석결과 긴장재의 긴장력 변화는 거더의 동적거동에 영향을 주지 않았으며 초기처짐에만 영향을 주었다. 긴장재의 양에 따라서는 거더의 동적거동이 다르게 나타났으며 긴장재의 양이 적을 수록 동적처짐은 증가하였다. 이를 바탕으로 거더의 동적증폭계수(DAF)를 산출하였으며, 이 결과 긴장재가 없는 경우에도 도로교표준시방서에서 정한 기준 값보다 매우 작은 거동을 보였다.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.159-168
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• 2012

본 연구에서는 해성 점성토에 대하여 반복 삼축시험을 실시하고 응력-변형률 관계 및 유효응력경로 특성 분석을 통해 동적 변형 및 강도 특성을 조사하였다. 시험에 사용된 시료는 일본 도쿠시마현의 코마츠시마 항 인근에서 채취된 점성토이며, 반복 삼축시험으로 동적 비배수 삼축시험, 동적 비배수 삼축시험 후 동적 삼축변형시험, 다단계 동적 비배수 삼축시험, 동적 삼축 변형시험 등 4종류의 시험을 수행하고, 시험 주파수로서 0.1 및 0.01 Hz을 적용하였다. 본 연구 결과 0.01 Hz로 수행된 동적 삼축시험 결과는 0.1 Hz로 수행된 삼축시험 결과보다 평균유효응력의 감소량이 크며, 반복 하중은 해성 점성토의 구조적 약화를 초래하고 초기 거동시 발생하는 간극수압과 밀접하게 관련이 있는 것으로 나타났다. 또한 미소변형률 영역에서 등가 탄성계수는 시험 횟수가 증가함에 따라 점차 감소하며, 감쇠비는 점차 증가하는 것으로 보아 변형계수는 반복 하중으로 인한 전단변형률의 축척에 따른 변형률 의존 거동에 관련하는 것으로 판단된다.

• Tunnel and Underground Space
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• v.13 no.3
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• pp.180-186
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• 2003

The fracture processes under dynamic loading in tension were simulated using a proposed numerical approach and analyzed to determine dynamic tensile strength. The dynamic tensile strength and the scatter of the strength data decreased with increasing uniformity coefficients. The differences of static and dynamic tensile strength were due to the stress concentrations and redistribution mechanisms in the rock specimen. Although there were different mechanisms for the static and dynamic fracture processes, the static and dynamic tensile strengths were close to the mean microscopic tensile strength at high values of the uniformity coefficient. This paper shows that the rock inhomogeneity has an effect on dynamic tensile strength and is a factor that contributes to the different specimen strengths under dynamic and static loading conditions.

• Journal of Korean Society of Transportation
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• v.23 no.7 s.85
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• pp.125-136
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• 2005

The goal of this paper is to develop freeway Origin-Destination (OD) demand estimation model using VDS and AVI data. The formulation of methodology proposed in this paper includes traffic flow technique to be able to remove the bi-level problem and optimal solution algorithm using a kalman filter algorithm. The proposed dynamic OD estimation model use ilk and off-ramp volumes collected from VDS and partial OD collected from AVI data to raise the accuracy of dynamic OD estimation. The proposed model is evaluated by using the real-time data of SOHAEAN freeway, South Korea. The result of the proposed dynamic OD estimation model based on VDS and AVI data is better than that of based on VDS data. The more AVI systems are equipped at on and off-ramp, the more excellent result of estimation accuracy is expected.

• Journal of Korea Multimedia Society
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• v.5 no.5
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• pp.488-493
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• 2002

MPEG-4 movies are composed of several media objects, organized in a hierarchical fashion. Those media objects are served to the clients as elementary streams. To play the movie, client players compose the elementary streams according to the meta- information called the scene graph. The meta-information streams are delivered as BIFS and OD elementary stream. Using dynamically generated BIFS and OD streams, we can provide a service something differs from traditional file services. For example, we can insert weather or stock information into the bottom of the screen while an existing movie was played in the screen. In this paper, we propose a dynamic service framework and dynamic server. Dynamic service framework is an object-oriented framework dynamically generating BIFS and OD streams based on the external DB information. Dynamic server provides a GUI for the server management and interface for registering dynamic services. In this framework, the dynamic service has the same interface as a file service. So, a dynamic service is considered as a file service by clients and other services.