• Computational Structural Engineering
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• v.10 no.4
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• pp.195-203
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• 1997

The interaction between cracks and stress wave due to impact and explosive loads is numerically calculated in the study. The interaction and the effects of stress wave are numerically examined with the application of Bicharacteristic Method. This method has been used with confidence for its reliability in reproducing the realistic and physical wave pattern in the complete solution domain. The dynamic stress intensity factor, K/sub I/(t) for cracks under impact loads are numerically simulated and its results are compared favorably with Kalthoff's experimental output. Also the influence of stress wave to the dynamic stress intensity factor for the case of two symmetric holes around cracks are investigated. The results of study are also compared favorably with the experiment and proven to be applied to the structures exposed to impact and explosive loads.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.995-1000
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• 2016

The maximum cross-correntropy (MCC) algorithm with a set of random symbols keeps its optimum weights undisturbed from impulsive noise unlike MSE-based algorithms and its main factor has been known to be the input magnitude controller (IMC) that adjusts the input intensity according to error power. In this paper, a normalization of the step size of the MCC algorithm by the power of IMC output is proposed. The IMC output power is tracked recursively through a single-pole low-pass filter. In the simulation under impulsive noise with two different multipath channels, the steady state MSE and convergence speed of the proposed algorithm is found to be enhanced by about 1 dB and 500 samples, respectively, compared to the conventional MCC algorithm.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.499-505
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• 2005

Underwater explosion shock response analysis of a nonlinear double resiliently mounted equipment on a MIL-S-901D Large floating Shock Platform(LFSP) was carried out using LS-DYNA3D/USA. As a nonlinear double resiliently mounted equipment, real main engine module of naval ship was considered, where the engine, bearing, and base frame including sound enclosure were treated as rigid bodies with six degrees of freedom. The nonlinear effects of resilient mounts on its shock response characteristics were examined, and the usefulness of our suggested method was also confirmed comparing with calculation results by the equipment maker.

• Transactions of the KSME C: Technology and Education
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• v.3 no.2
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• pp.131-140
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• 2015

The mono-ski for the paraplegia designed to skiing is formed as seat bucket on the sled. The impact force transferred by snow surface during skiing is absorbed by the leg joints of normal human, but it is transferred to the human body on the seat when using mono-ski. Most of commercially available mono-ski have absorbing device and link mechanism between seat and ski mount in order to complement it. In this study we developed the comfort evaluation model that could provide skiing simulation of mono-ski with hydraulic damper and analyzed vibrational acceleration occurred during skiing uneven surface. The evaluation method used in this study is the international standard BS6841. We evaluated comfort performance of mono-ski in accordance with nozzle adjustment of hydraulic damper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.9
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• pp.801-805
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• 2016

In this paper, engine clutch engagement shock is analyzed during the mode change of plug-in hybrid electric vehicles. Multi-driving mode includes the EV (electric vehicle) mode, HEV (hybrid electric vehicle) mode, and engine operating mode. Depending on the mode change, the engine clutch is either engaged or disengaged. The magnitude of shock during clutch engagement is very important because it impacts vehicle acceleration and clutch synchronization speed, which affects ride comfort substantially. The performance simulator of plug-in hybrid electric vehicles was developed using MATLAB/Simulink. The simulation results show that the mode change control algorithm is necessary for minimizing shock during clutch engagement.

• KDI Journal of Economic Policy
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• v.16 no.3
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• pp.3-44
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• 1994

본교(本橋)는 백터자기회귀모형(自己回歸模型)(VAR)에 비하여 작성과정이 까다롭고 복잡하지만 경제구조의 파악이 용이하고 경제체계내에 주어진 충격의 해석이 분명한 연립방정식(聯立聯立方程式) 구조모형(構造模型)을 사용하여 경기순환(景氣循環)의 원인을 밝히고자 하였다. 새로 작성된 경기순환모형(景氣循環模型)은 거시경제(巨視經濟) 분기모형(分期模型)으로서 추정기간은 1972년부터 1992년까지 21년으로 통계청(統計廳) 기준의 제1순환기부터 제5순환기까지 포함하고 있으며, 경기순환(景氣循環)의 원인분석을 위해서 가상적(假想的) 시뮬레이션(counter factual simulation) 기법을 사용하였다. 본고(本稿)는 향후 경기순환(景氣循環)의 안정(安定)을 도모하거 위해서 다음의 몇가지 결론을 내리고 있다. 첫째, 건설투자(建設投資)는 경기변동(景氣變動)의 진복(振福)을 확대(擴大)시켜 온 경향이 있기 때문에 경기부양(景氣浮揚) 및 경기진정(景氣鎭靜)을 위한 정책변수로 바람직하지 않다. 왜냐하면 정부가 경기변동(景氣變動)을 감지(感知)하기까지는 시간이 걸리며, 경기변동(景氣變動)의 체감 직후 건설투자(建設投資)를 통해서 경기부양(景氣浮揚) 혹은 경기진정(景氣鎭靜)을 이루고자 하더라도 정책수립부터 정책효과의 가시화(可視化)에까지 이르는 시차(時差)로 인하여 건설투자(建設投資)가 정부의 의도와는 반대로 경기순행적(景氣順行的)인 역할(役割)을 할 가능성이 있기 때문이다. 둘째, 통화(通貨)가 생산(生産) 및 물가변동(物價變動)에 미치는 영향은 서로 상충관계(相衝關係)(trade-off) 에 있는 것으로 보이기 때문에 정부는 민간신용(民間信用) 등 통화변수(通貨變數)를 경기조절수단(景氣調節手段)으로 사용할 경우에는 사전에 정책효과(政策效果)를 충분히 고려해서 시행해야 할 것이다. 셋째 해외도매물가(海外都賣物價), 원유도입가격(原油導入價格) 및 국제상품가격(國際商品價格) 등 해외물가변수(海外物價變數)의 변동은 GNP는 물론이고 큰 폭의 물가변동(物價變動)을 초래하기 때문에, 해외부문(海外部門)의 충격에 따른 경기변동(景氣變動)을 안정시키기 위해서 정부는 유가자유화(油價自由化)를 통한 유류가격안정(油類價格安定)및 원유비양수준(原油備養水準)의 제고(提高), 해외원자재(海外原資材) 수입선(輸入先)의 다변화 등을 통하여 해외물가충격(海外物價衝擊)이 국내경제에 미치는 영향을 최소화하도록 노력해야 할 것이다.

• Journal of the Korean Institute of Gas
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• v.25 no.3
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• pp.53-58
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• 2021

The number of patients with cardiovascular diseases who experience an out-of-hospital cardiac arrest (OHCA) are increasing among young adults as well as the aged population. An automated external defibrillator (AED) is vital in improving survival rates of OHCA victims. Survival rates of OHCA were shown to decline exponentially in time to defibrillation, yet studies in Korea are uncommon that captures the properties of their survival rates in examining optimal locations of AEDs. In this study, we worked on the maximal gradual coverage location problem (MGCLP) with exponential decay coverage function to decide on their optimal locations. The exponential decay coverage function mitigates the drawback of over-estimating survival rates of OHCA patients. It is expected that a more sophisticated facility location problem will be developed to identify the "emergent" characteristics of pedestrians who responds to the OHCA occurrence by incorporating random pedestrian locations and movement through simulation.

• Journal of Korean Society of Disaster and Security
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• v.16 no.3
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• pp.45-56
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• 2023

In this study, the application of ANC (Active Noise Control) technology to address inter-floor noise was explored. To achieve this, an ANC system was developed to manage the heavy impact sound within the frequency range of 40 to 500 Hz. The ANC system utilized an adaptive filter employing a feedforward approach based on the Fx-LMS algorithm. To set up the ANC system, a comprehensive analysis of various variables within the system was performed using computational simulations. This process enabled the identification of optimal filter settings and system configuration arrangements. In addition, the ANC system was implemented in the inter-floor noise test room at the Korea Conformity Laboratories (KCL). Through a certified standard testing procedure, it was confirmed that the ANC system led to a 4 dB reduction in inter-floor noise when the system was activated compared to when it was turned off. The results of this study indicate that the developed ANC system has an effect significant enough to elevate the rating criteria by one level for heavy impact sound.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.361-366
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• 2017

As the recent development of computing architecture and application software technology, real world simulation, which is the ultimate destination of computer simulation, is emerging as a practical issue in several research sectors. In this paper, metal plate motion in a square shock tube for small time interval was calculated using a supercomputing-based fluid-structure-combustion multi-physics simulation tool called Illinois Rocstar, developed in a US national R amp; D program at the University of Illinois. Afterwards, the simulation results were compared with those from experiments. The coupled solvers for unsteady compressible fluid dynamics and for structural analysis were based on the finite volume structured grid system and the large deformation linear elastic model, respectively. In addition, a strong correlation between calculation and experiment was shown, probably because of the predictor-corrector time-integration scheme framework. In the future, additional validation studies and code improvements for higher accuracy will be conducted to obtain a reliable open-source software research tool.

• Journal of the Korean GEO-environmental Society
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• v.21 no.5
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• pp.23-33
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• 2020

As the scale of the economy expands, the number of cases of damage in enclosed spaces such as tunnels is increasing due to the accident of transportation vehicles of dangerous substances such as explosive flammable materials that have increased rapidly. In the case of road tunnels in particular, in the aspect of protection against the long-winding trend and the environment in the downtown area, the number of cases of passing through the downtown area increases, and securing the safety of structures against unexpected extreme disasters such as explosions during tunnel passage is very urgent. For this reason, developed countries are already conducting a review of internal bombardment, but there are almost no evaluation and countermeasures for explosion risk in Korea. Therefore, in this study, in order to evaluate the explosion safety of road tunnels, a boiling liquid explosive explosion (BLEVE), which is considered to have the greatest explosion load among vehicles driving on the road, is set as a reference explosion source, and the equivalent TNT explosion load is used for simulation of the explosion. A method of conversion was presented. In addition, by applying the derived explosion load, dynamic behavior simulation was performed by assuming various variables for the tunnel, and the explosion safety of the tunnel was analyzed.