• 해양환경안전학회지
• /
• 제29권4호
• /
• pp.356-362
• /
• 2023

기후 변화에 따른 위험성은 전 세계적으로 오랜 기간 강조되고 있으며, 이를 극복하기 위한 노력은 해운분야에서도 국제해사 기구를 중심으로 이어지고 있다. 연소과정에서 발생한 매연을 제어하기 위하여 매연 생성 특성에 관한 연구는 필수적이다. 본 연구에서는 에틸렌 가스를 기반으로 한 대향류 확산화염에서 불활성 기체인 질소를 혼합하여 화염온도, 화염형태, 매연 생성 관련된 화학종의 상태변화를 확인하기 위해 광소멸법과 화학반응 수치해석을 수행하였다. 연구 결과. 질소의 혼합비율이 증가함에 따라 화염온도 감소와 매연체적분율 감소로 이루어졌다. 매연 입자가 분포하는 구간도 감소하였으며, 30% 이상 혼합비율이 높아지면 체적분율 감소율이 감소하였다. 매연 성장에 관여하는 화학종들의 몰분율도 감소하였다. HACA 반응 관련 화학종은 탄화수소 연료 비율에 따라 영향을 받으나, 홀수탄소 경로 관련 화학종은 탄화수소 연료 비율뿐만 아니라 화염온도 영향을 받는 것을 확인하였다.

• 국제학술발표논문집
• /
• The 7th International Conference on Construction Engineering and Project Management Summit Forum on Sustainable Construction and Management
• /
• pp.32-41
• /
• 2017

Accidents on offshore oil and gas platforms (OOGPs) usually cause serious fatalities and financial losses considering demanding environment platforms locate and complex topsides structure platforms own. Evacuation planning on platforms is usually challenging. The computational tool is a good choice to plan evacuation by emergency simulation. However, the complex structure of platforms and varied evacuation behaviors usually weaken the advantages of computational simulation. Therefore, this study developed a simulation model for OOGPs to evaluate different evacuation plans to improve evacuation performance by integrating building information modeling (BIM) and agent-based model (ABM). The developed model consists of four parts: evacuation model input, simulation environment modeling, agent definition, and simulation and comparison. Necessary platform information is extracted from BIM and then used to model simulation environment by integrating matrix model and network model. During agent definition, in addition to basic characteristics, environment sensing and dynamic escape path planning functions are also developed to improve simulation performance. An example OOGP BIM topsides with different emergent scenarios is used to illustrate the developed model. The results showed that the developed model can well simulate evacuation on OOGPs and improve evacuation performance. The developed model was also suggested to be applied to other industries such as the architecture, engineering, and construction industry.

• 한국화재소방학회논문지
• /
• 제27권2호
• /
• pp.75-79
• /
• 2013

본 연구는 구획화재의 출입구를 통한 연기밀도를 정량적으로 측정하고 측정기법의 신뢰성을 평가하기 위해 불확실성 해석을 수행한다. 메탄 화재 강도에 따른 축소모형 구획공간의 출입구 상층부를 통해 유출되는 연기 유동에 대해 광소멸 측정을 수행하고 Bouguer's의 법칙을 적용하여 연기밀도를 산정하였다. 광투과율, 경로길이, 질량비광소멸상수에 대하여 연기밀도의 측정 불확실도를 평가하였으며 계산된 연기밀도 측정의 확장불확실도는 20% 정도이며 신뢰수준은 95% 이다. 준정상상태의 화재 발열량에 대하여 출입구에서의 평균 연기밀도를 산정하였으며 구획공간내부의 총괄당량비 증가에 따라 출입구의 연기농도가 선형적으로 증가하는 경향을 보였다.

• Journal of Welding and Joining
• /
• 제11권3호
• /
• pp.22-33
• /
• 1993

Arc sensor is indispensable to arc welding robot systems for compensating the joint misalignment such as mismatch of the workpiece, ill-conditioned positioner and thermal deformation during welding. Furthermore, the amount of these mismatches cannot be preivously expected, and changes from time to time. There are many kinds of seam trackers for correcting the welding path of the robot, where non-contact type sensors arc prevalently used in arc welding robot systems. In this study, an arc sensor was developed for GMA and FCA welding robot system. Since the arc sensor uses the arc characteristics during welding, the operating principle of the arc sensor must be adjusted according to the welding condition. Especially in GMA welding with the $CO_{2}$ shielding gas, the welding arc is not stable because of the short circuit and non-axial globular transfer mode of the molten droplet. In this study, the 2nd order least square curve fitting algorithm was adopted and the applicability of this algorithm was investigated for robot welding systems. For easy usage of the arc sensor, the operating parameters for arc sensor were limited to eight which can be easily determined by the operator.

• 대한기계학회논문집B
• /
• 제41권10호
• /
• pp.667-673
• /
• 2017

공개소스 전산유체 해석 라이브러리인 OpenFOAM을 이용하여 음극 지지체형 고체산화물 연료전지의 온도균일성에 관한 연구를 수행하였다. 3가지 유형의 유동흐름(병행류, 대향류, 직교류)에 대하여 수치해석이 이루어졌다. 다공성 물질내에서의 기체의 흐름은 유효확산계수를 이용하여 계산하였고 분리판의 리브 영향도 고려하였다. 전기화학반응의 계산을 위하여 실험식으로부터 얻은 집중내부저항 모델이 사용되었다. 수치해석 결과 대향류가 가장 균일한 온도분포를 나타내었다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.693-698
• /
• 2002

For the evaluation of the plasma display panel (PDP)'s noise, vibration and sound characteristics of fanless PDP are measured and investigated. PDP is a type of two-electrode vacuum tube which operates on the same principle as a household fluorescent light. An inert gas such as argon or neon is injected between two glass plates on which transparent electrodes have been formed, and the glass is illuminated by generating discharge. For this discharge, both high voltage and currents are needed and cause an acoustic noise. We investigated the noise characteristics connected with both a electromagnetic elements from SMPS to panel through X, Y and logic board, and a mechanical elements form panel to case through transfer path which related with vibration and heat. To reduce the noise of PDP, a discharge pulse memory design related with both higher brightness and lower power consumption is important and mechanical characteristics connected with dissipation process of both heat and vibration generated by panel discharge must be investigated.

• Journal of Biosystems Engineering
• /
• 제24권3호
• /
• pp.209-216
• /
• 1999

A self-travelling sprayer was developed to avoid the exposure of an operator to agricultural chemicals and exhaust gas, to improve safety and to increase working efficiency during the application and transport work in the greenhouses. This system consists of self-travelling system and the control system for application and safety device. The auto-spray car is equipped with a liquid chemical tank of 80l capacity. The travelling system adopted mechanical steering system which link mechanism of front wheel is guided by guide rollers. The sprayer travels along the guiding pipe which is set on the furrow in the greenhouses. The sprayer stops automatically applying and traveling when the liquid chemical tank becomes empty or when the sprayer reach the turning point. The spray booms swings in a vertical plane. The control system of safety devices controls the automatic stop of the sprayer when there is an obstacle on the traveling path, or when the battery becomes discharged. The auto-spray car traveled smoothly and steadily along the guide pipe during traveling straightly and turning on the ground.

• 한국자동차공학회논문집
• /
• 제16권1호
• /
• pp.100-105
• /
• 2008

Cross-drilling on the brake disc is generally known as a way of improving cooling efficiency. In other theories, cross-drilled holes act like a path of gas or water and are also known that they can reduce fading and wetting of brake rotors. However, in disc rotors with cross-drilling, thermal crack phenomena have been reported more frequently and more manufacturing cost should be paid than non cross-drilled disc rotors. In this study, to examine various effects of cross-drilling on the brake disc, two kinds of brake disc rotors, cross-drilled and non cross-drilled, were used in computational fluid dynamic analyses and dynamometer tests.

• Tribology and Lubricants
• /
• 제30권1호
• /
• pp.15-20
• /
• 2014

A more accurate expression for effective viscosity is obtained using a linear regression of the data from Fukui-Kaneko's model, which are obtained through numerical calculations based on the linearized Boltzmann equation. Veijola and Turowski's expression is adopted as a base function for effective viscosity. The four coefficients in that equation are optimized, and sensitivity analysis is conducted for these coefficients. The results show that the coefficient for the first-order Knudsen number is the most accurate, whereas the coefficient in the exponential of the Knudsen number is the least accurate compared with Fukui-Kaneko's results. The expression for effective viscosity is accurate within 0.02% rms of Fukui-Kaneko's results for the inverse Knudsen numbers from 0.01 to 100 and surface accommodation coefficients ranging from 0.7 to 1.

• 한국수소및신에너지학회논문집
• /
• 제20권4호
• /
• pp.265-273
• /
• 2009

Proton Exchange Membrane Fuel Cell (PEMFC) has low operating temperature and high efficiency. And PEMFC consists of many components as bipolar plate, gas diffusion layer, membrane etc.. Flow-field in bipolar plate roles path for transporting reactants to membrane. Therefore a design of flow-field has an effect on PEMFC's performance. In this study, Computational Fluid Dynamics (CFD) simulations were performed for comparing mixed multiple serpentine (MMS) flow-field and multiple serpentine (MS) flow-field. And we studied an effect according to change mixing region design in MMS flow-field. Finally the applicability of results is verified by performing CFD simulation about fixed MMS flow-field which is combined good designs.