• 제어로봇시스템학회논문지
• /
• 제20권5호
• /
• pp.570-577
• /
• 2014

This paper describes the design of a force applying system for a smart phone curved glass molding system and its characteristic test. The force applying system is composed of a motor and gear, a rectilinear movement structure, a force sensor, an LVDT (Linear Variable Differential Transformer) sensor, an up and down moving block, and so on. The system precisely controls the applying force and time to the plane glass because the glass can be easily destroyed under applied force, and can be bent imperfectly. As a result of the characteristic test, the curved glass can be manufactured using this system, and the holding time under 0N force, the applying force to the plane glass, the time for applying from 0N to maximum force, and the holding time under maximum force at the manufacture feasible temperature $620^{\circ}C$ were found.

• Journal of Welding and Joining
• /
• 제35권1호
• /
• pp.34-42
• /
• 2017

This paper presents a comparative study of the AC and MFDC resistance spot welding process with consideration of sheet thickness. The previous studies have confirmed that there is difference in the optimum welding current and expulsion current with AC and MFDC. The aim of this study was revealing the effect of sheet thickness on weldable current range and expulsion behavior for AC and MFDC welding processes. The optimum welding current of AC was lower (1.6 kA) than MFDC welding process in 0.8 mm sheet thickness. Early nugget growth being caused by the peak current of AC developed weld interface deformation, which resulted in suppressing the growth of corona bond and occurrence of low current expulsion. The resistance spot welding for thicker sheet (1.4 mm) required lower current of 0.6 kA for the expulsion on the MFDC welding process. The growth of contact diameter (size of corona bond) and button diameter was linear up to the expulsion current with MFDC welding process. Therefore, more attention is required when the AC and MFDC resistance spot welding process is applied for different thickness of steel sheet combination for automotive application.

• 한국융합학회논문지
• /
• 제4권2호
• /
• pp.21-27
• /
• 2013

점용접은 자동차 산업에서 많이 사용되어지는데 조립공정의 자동화로 인하여 경제성과 차체 중량을 높이지 않아 자동차 연비 개선효과가 있다. 그러나 차량 주행시 노면으로부터 불규칙적인 하중전달 및 진동으로 인하여 점 용접부에 응력집중이 발생하고 피로파괴가 종종 발생한다. 이에 대하여 강성변화를 고려한 점용접부의 피로수명 평가는 필수적이다. 본 논문에서는 선형정적해석을 수행하여 취약부위를 파악하였다. 점용접부의 피로특성을 획득하였고, 시간영역에서 3단계의 하중이력을 도출하여, 준정적 피로해석에 조건으로 설정하여 수행하였다. 또한 점용접부에 대한 피로수명예측 방법은 기존 방법과 피로누적으로 인한 손상방법을 적용하여 나타낸 결과를 가지고 비교분석하였다.

• 한국대기환경학회지
• /
• 제19권6호
• /
• pp.719-731
• /
• 2003

In order to maintain and manage ambient air quality, it is necessary to identify sources and to apportion its sources for ambient particulate matters. The receptor methods were one of the statistical methods to achieve reasonable air pollution strategies. Also, receptor methods, a field of chemometrics, is based on manifold applied statistics and is a statistical methodology that analyzes the physicochemical properties of gaseous and particulate pollutant on various atmospheric receptors, identifies the sources of air pollutants, and quantifies the apportionment of the sources to the receptors. The objective of this study was 1) after obtaining results from the PMF modeling, the existing sources of air at the study area were qualitatively identified and the contributions of each source were quantitatively estimated as well. 2) finally efficient air pollution management and control strategies of each source were suggested. The PMF model was intensively applied to estimate the quantitative contribution of air pollution sources based on the chemical information (128 samples and 25 chemical species). Through a case study of the PMF modeling for the PM-10 aerosols, the total of 11 factors were determined. The multiple linear regression analysis between the observed PM-10 mass concentration and the estimated G matrix had been performed following the FPEAK test. Finally the regression analysis provided quantitative source contributions (scaled G matrix) and source profiles (scaled F matrix). The results of the PMF modeling showed that the sources were apportioned by secondary aerosol related source 28.8 ％, soil related source 16.8％, waste incineration source 11.5%, field burning source 11.0%, fossil fuel combustion source 10%, industry related source 8.3％, motor vehicle source 7.9%, oil/coal combustion source 4.4％, non-ferrous metal source 0.3％. and aged sea- salt source 0.2％, respectively.

• 한국산학기술학회논문지
• /
• 제12권3호
• /
• pp.1085-1090
• /
• 2011

철도차량의 안전성을 확보하기위해서는 견인성능 및 속도의 변동성을 고려하여 감속기의 피로해석에 관한 연구를 수행하는 것이 중요하다. 본 논문은 고속철도차량 감속기 기어의 변동하중하에서 피로파괴에 대하여 준정적 유한요소해석과 선형 Miner's Rule에 의한 내구성해석을 수행하였다. 해석을 위한 변동하중이력은 열차견인성능곡선과 상업운전조건에서 운전선도를 기초로 MSC.ADAMS의 동역학 해석에 의하여 구축하였다. 또한 감속기 피로수명은 기어표면의 침탄부 효과를 고려한 유한요소모델을 사용하여 변형률-수명접근법에 의하여 예측하였다. 해석결과로부터 급출발에 의한 빈번한 높은 기동토크와 정차역수의 증가는 철도차량 감속기 기어수명을 감소시킴을 알 수 있었다.

• Journal of Biosystems Engineering
• /
• 제35권3호
• /
• pp.163-168
• /
• 2010

With income growth and "well-being" trends, sales of corn has been increased recently. Corns are processed at processing facilities on the main production site. Corn processing steps include removing bract, steaming, vacuum packing, and storing. To replace manual corn bract removing, some bract removing machines were imported and used. However, the machines were abandoned shortly, because of high damaging ratio of corns. In this research, factors of successful bract removing was studied with rotating rollers and air-injection nozzles to develop corn bract removing system. The test device was composed of a cylindrical roller, an air spray nozzle, a regulator, and a motor. Designing factors were roller type, diameter of air spraying nozzle, spraying angle, and spraying pressure. The measured factors were bract removing rate and damaging rate. It was found that optimum cylindrical roller surface shape was cylindrical roller and linear grove roller. This roller shape produced lowest damaging rate. Test results of the efficacy of preprocessing showed that the air spraying after preprocessing produced highest performance. The rotational speed and inclination of the roller didn't affect the bract removing performance. Optimum injection angle of the air jet nozzle was $70^{\circ}$. To increase bract removing rate and to reduce corn damage, required injection pressure and injection nozzle diameter were decided to less than 0.4 MPa and 2.5 mm, respectively. More than 3 times of nozzle passing produced good bract removing performance and there were no significant difference between the number of passing times.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 춘계학술대회 논문집
• /
• pp.466-471
• /
• 2014

The interior vehicle noise due to the exterior aerodynamic field is an important topic in the acoustic design of a car. The air flow detached from the A-pillar and impacting the side windows are of particular interest as they are located close to the driver / passenger and provides a lower insulation index than the trimmed car body parts. This paper presents a numerical analysis method for a simplified vehicle model. The internal air cavity including trim component are included in the simulation. The car body includes the windshield and two side windows. The body is made of aluminum and trimmed with porous layers. The methodology proposed in this paper relies on two steps: the first step involves the computation of the exterior flow and turbulence induced non-linear acoustic field using PowerFlow. The second step consists in the computation of the vibro-acoustic transmission through the window using the finite element vibro-acoustic solver Actran. Additionally in order to validate the numerical process, an experimental set-up has been created based on the simplified vehicle. The vibration of the windshield and windows, the total wind noise level results and the relative contributions of the different windows are then presented and compared to measurements. The influence of the flow yaw angle (different wind orientation) is also assessed.

• Tribology and Lubricants
• /
• 제35권6호
• /
• pp.369-375
• /
• 2019

This paper presents a new method on how to calculate the thrust forces acting on an auto-leveling device in headlamps for passenger vehicles. The leveling device is used to lower the angle of lights when a load in the trunk of the vehicle lifts it. In the process of the headlamp design, it is imperative to predict the external forces so that the designers can decide whether to proceed or not. The device is composed of three pivot joints with no reaction moment, a plate that holds the lamp, and a leveling motor that changes rotation to linear motion. In this study, force balance, moment balance, and geometric compatibility are applied to the leveling device system so that a nonlinear system of equations can be derived; the multi-dimensional Newton-Raphson algorithm is then used to solve these. A sensitivity analysis is carried out to verify which design variables affect the system the most: the mass of the lamp and the height between the pivot and leveling device affect the thrust forces the most. Then, considering the friction forces between the moving parts, the hysteresis of the forces are derived. An experimental apparatus, designed and developed in this study, is used to verify the exactness of the derived equations. The results from experiments coincide well with the calculated results. The friction hysteresis, in particular, proves this upon analysis.

• 한국식품위생안전성학회지
• /
• 제8권3호
• /
• pp.163-169
• /
• 1993

ICR 마우스를 이용하여 계면 활성제인 LAS-Na 와 MES의 급성 경구독성을 실시하였다. 6주령된 마우스 LAS-Na는 0, 1,000, 1,320, 1,780, 2,280, 3,000 mg/kg의 용량으로 MES는 0, 1,000, 1,560, 2,450, 3,830, 6,000mg/kg의 용량으로 1회 경구 투여한 후 14일간 관찰하였다. 두 물질 모두 관찰 기간동안 대조군에 비하여 유의성 있는 체중변화는 관찰되지 않았다. 시험물질과 관련된 주요 임상증상으로는 설사, 활동성 감소, 입모 등이 관찰되었다. 사체에 대한 부검결과 시험물질에 의한 것으로 판단되는 소장 점막의 충혈이 소수례 관찰되었으며, 생존 동물에서는 특이한 만한 이상소견은 발견되지 않았다. 이상의 결과로부터 $LD_{50}$값은 LAS-Na의 경우 수컷과 암컷에서 각각 1,319 mg/kg, 1,402 mg/kg이었으며, MES의 경우 수컷에서는 2,040 mg/kg, 암컷에서는 2,546 mg/kg으로 산출되었다.

• 조명전기설비학회논문지
• /
• 제14권3호
• /
• pp.29-37
• /
• 2000

본 논문에서는 TMS320C32 DSP를 사용하여 저속에서 구동되는 반송용 펀측식 전행 유도전동기의 슬립 각 주파수에 의한 벡터제어를 이용하여 추력제어하였다. 먼저, 반송용 편촉식 선형 유도전동기를 설계 및 제작하고, 이를 해석하였다. 저속에서 제풍의 운반시에 안정성있은 구동올 위해서 벡터제어에 의한 추력제어를 하였고, 정위치 제어를 하기 워해서 Ziegles- Nichols법을 이용하여 PiD제어기를 설계하였다. 저속에셔의 종량부하흘 갖는 반송용 선형기기에서 PID제어기에 추력제어가 가능한 벡터제어기법을 부가한 결과는 제품외 운반시에 안정성있는 구동을 하였으며, 정위치제어를 위한빠른 응답특쟁 및 soft start/stop을 이루었으며, 부하 변동시에도 제동시에 정위치제어를 위한 빠른 응탑 특성의 결과를 얻었다.