• 드라이브 ㆍ 컨트롤
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• 제19권3호
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• pp.1-8
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• 2022

In this paper, the design of automatic impact force control mechanism of hydraulic breaker was studied. The control mechanism uses the change of piston upper chamber pressure, when the hydraulic breaker impacts various strength rock. The piston stroke is controlled by rock strength sensing valve, piston stroke switching valve, and piston control valve. It is imperative to denote the area of each valve section, the spring constant of the spring. It provides convenience to users by automatically adjusting the appropriate striking force, according to the strength of the rock. Additionally, by increasing work productivity, it can contribute to reducing greenhouse gas emissions due to fuel efficiency reduction.

• 한국시뮬레이션학회논문지
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• 제8권4호
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• pp.109-124
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• 1999

The major objective of this research is to design and build the variable structure DEVS modeling & simulation framework. To do this, we have proposed the direct message passing mechanism between the model and its simulator to deal with the structural demand from the model during the simulation. In this approach, four types of basic messages are introduced for the vertical(creation/deletion of the child) and horizontal(creation/deletion of the brother) structural changes. Proposed methodology has been successfully applied to the multi-processor system and the forest fire information system.

• 한국인쇄학회지
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• 제25권1호
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• pp.53-64
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• 2007

Gravure printing is the most useful printing process than any other engraving printing method. According to the cell which is variable size and depth, ink is transferred substrates. So, the amount of ink from cells has a great effect on the qualities of final printed products. The variables effect on the printability of final products are proportion of the width and length, the rhelogical properties, roll speed etc. However the mechanism of gravure is difficult to study scientifically because of high speed and excessively small size of the cell. To approach the mechanism we experimented the real test by using gravure printability. The condition of variables of IGT is pressure and velocity. By using Polyflow 3. 10. 0 simulation software, we built up the theoretical model under the constant variables. Then, we compared the real test with the simulation results. Therefore, it is studied the mechanism of gravure scientifically and it can be analysed the effect of the variable conditions.

• ETRI Journal
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• 제39권3호
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• pp.345-352
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• 2017

Traffic management is a highly beneficial mechanism for satisfying quality-of-service requirements and overcoming the resource scarcity problems in networks. This paper introduces an optimal connection admission control mechanism to decrease the packet loss ratio and end-to-end delay in cognitive radio sensor networks (CRSNs). This mechanism admits data flows based on the value of information sent by the sensor nodes, the network state, and the estimated required resources of the data flows. The number of required channels of each data flow is estimated using a proposed formula that is inspired by a graph coloring approach. The proposed admission control mechanism is formulated as a semi-Markov decision process and a linear programming problem is derived to obtain the optimal admission control policy for obtaining the maximum reward. Simulation results demonstrate that the proposed mechanism outperforms a recently proposed admission control mechanism in CRSNs.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.569-570
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• 2007

• 정보보호학회논문지
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• 제19권3호
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• pp.95-105
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• 2009

본 논문은 VoIP의 주요 보안 위협인 스팸에 대응하기 위한 목적으로 VoIP 스팸 탐지 기술의 성능평가를 위한 시뮬레이션 모델을 설계하고 있다. 성능평가 시뮬레이션 모델은 입력 데이터를 제공하는 기능과 출력 데이터를 분석하는 기능을 갖는다. 본 논문에서는 VoIP스팸 탐지 기술의 성능평가 입력 데이터를 위하여 VoIP 발신자 특성을 고려하여 네 종류의 Caller 모델을 개발하였고, 각 caller 모델은 결정된 패턴 내에서 call을 생성하게 된다. 성능평가는 SPIT (Spam over Internet Telephony) Level 결정 알고리즘을 대상으로 수행하고, 성능평가의 지표 도출을 통해 평가 알고리즘의 성능 지수를 산정한다. 성능평가 모델은 DEVS 형식론 기반으로 설계하였으며 DEVSJAVA$^{TM}$를 이용한 모델링 및 시뮬레이션을 통해 설계된 모델을 검증하였다.

• 한국시뮬레이션학회논문지
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• 제19권1호
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• pp.13-22
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• 2010

본 논문에서는 해상 크레인이 인양하는 중량물의 운동 감쇠를 위하여 Tagline을 이용한 PD제어를 수행하였다. 해상 크레인 및 중량물을 각각 6자유도 운동을 하는 강체로 가정하고 뉴턴의 제 2법칙에 따라 운동 방정식을 유도하였다. 중량물의 운동을 감쇠하기 위한 제어 메커니즘으로 Tagline을 사용 하였고, 해상 크레인의 Deck에 설치한 Winch로 Tagline의 장력을 조절하였다. 장력을 조절하는 제어 알고리즘으로는 PD제어를 사용 하였다. 이를 바탕으로 수치적 제어 시뮬레이션을 수행하였다. 또한, 1/100 Scale의 모형 해상 크레인을 제작하고 실험을 통해 제어 시뮬레이션의 결과를 검증 하였다. 제어 시뮬레이션과 모형 시험 수행 결과 Tagline을 이용한 제어가 중량물의 운동을 감쇠시키는데 효과가 있음을 알 수 있었다.

• Geomechanics and Engineering
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• 제29권4호
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• pp.391-405
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• 2022

A newly proposed grouting simulation method, the sequential diffusion solidification method was introduced into the numerical simulation of combined bi-borehole grouting. The traditional, critical and difficult numerical problem for the temporal and spatial variation simulation of the slurry is solved. Thus, numerical simulation of grouting and blocking of flowing water in karst conduits is realized and the mechanism understanding of the combined bi-borehole technology is promoted. The sensitivity analysis of the influence factors of combined bi-borehole grouting was investigated. Through orthogonal experiment, the influences of proximal and distal slurry properties, the initial flow velocity of the conduit and the proximal and distal slurry injection rate on the blocking efficiency are compared. The velocity variation, pressure variation and slurry deposition phenomenon were monitored, and the flow field characteristics and slurry outflow behavior were analyzed. The interaction mechanism between the proximal and distal slurries in the combined bi-borehole grouting is revealed. The results show that, under the orthogonal experiment conditions, the slurry injection rate has the greatest impact on blocking. With a constant slurry injection rate, the blocking efficiency can be increased by more than 30% when using slurry with weak time-dependent viscosity behavior in the distal borehole and slurry with strong time-dependent viscosity behavior in the proximal borehole respectively. According to the results of numerical simulation, the grouting scheme of "intercept the flow from the proximal borehole by quick-setting slurry, and grout cement slurry from the distal borehole" is put forward and successfully applied to the water inflow treatment project of China Resources Cement (Pingnan) Limestone Mine.

• 한국전산유체공학회지
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• 제10권3호
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• pp.43-47
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• 2005

In this study, the numerical and dynamic simulation on staging problem including forward jet mechanism is conducted. The forward jet plays a vital role in staging, which jets out from aftbody. This staging environment needs full dynamic characteristics study and flow analysis for securing staging safety. Present study performs dynamic simulation of forebody and aftbody with flow analysis using the Chimera grid scheme which is usually used for moving body simulations. As a result, the separation mechanism using forward jet well work in staging for given initial conditions and reverse thrust, chamber pressure variation from experiments. Furthermore, it is found that the technique using forward jets for staging is excellent for securing the separation safety.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.410-415
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• 2004

Molecular dynamics simulations of nanoimprint lithography in which a stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA) surface are performed to study the deformation of polymer. Force fields including bond, angle, torsion, inversion, van der Waals and electrostatic potential are used to describe the intermolecular and intramolecular force of PMMA molecules and stamp. Periodic boundary condition is used in horizontal direction and $Nos\acute{e}$-Hoover thermostat is used to control the system temperature. As the simulation results, the adhesion forces between stamp and polymer are calculated and the mechanism of deformation are investigated. The effects of the adhesion force and friction force on the polymer deformation are also studied to analyze the pattern transfer in nanoimprint lithography. The mechanism of polymer deformation is investigated by means of inspecting the indentation process, molecular configurational properties, and molecular configurational energies.