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

• 한국기계가공학회지
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• 제16권4호
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• pp.127-134
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• 2017

A rotary table is a positioning device used in metalworking for the multiple axes of machine tools, and the utilization trend is increasing with machining efficiency. In the construction of a rotary table, the core technology is a power transfer unit that drives the table, typically a gear type and a roller gear cam type. As the rollers installed on the turret column have rolling movement on the contact surface of the roller gear cam, the roller gear cam type has the advantage of low wear, high load, and fast driving. Therefore, it is currently being replaced by a roller gear cam type. In this study, we researched a 5-axis machining method for the roller gear cam on a rotary table and a new method of applying double roller gear cam curve to reduce the noise and shock between the roller and the cam surface. We implemented the 5-axis machining process in this study using software to generate NC-code and machined the roller gear cams using a Mazak Integrex-200IV. We found that the roller gear cam and turret were able to identify mutual touch status and the noise from the operation of the roller gear cam was substantially reduced.

• 소성∙가공
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• 제21권4호
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• pp.234-239
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• 2012

This study examines the forming properties and forming loads needed to increase the edge thickness on the external face of a plate using finite element analysis(FEA). Recently, forming optimization techniques within FEA are being extensively used in designing the optimal forming conditions for processes like forging, extrusion, rolling, and spinning. Most of these existing forming operations involve reducing the volume per unit length, but research for increasing volume per unit length is not very extensive. For this study we chose an automotive engine flywheel which is a welded assembly of a plate and a gear with each component having a different thickness. We considered a forming technique to increase the thickness in order to allow the machining of the gear directly on the external face of plate alleviating the need for a weld. To study various forming techniques, we used the finite element method with the flow stress of material and incremental forming steps. We conclude from this study that the analysis of forming properties and forming loads by using the finite element analysis and testing is useful as a method to increase the thickness per unit length.

• 한국가스학회지
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• 제26권2호
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• pp.21-26
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• 2022

사륜구동은 구동력을 4바퀴에 모두 전달하기 때문에 노면과의 접지력이 상승하여 구동력이 상승한다. 하지만 그로 인해 연비가 저하되는 단점을 가지고 있다. 따라서 평소에 이륜구동으로 주행하다가 필요에 의해 선택적 사륜구동으로 변환하는 방법으로 사륜구동을 많이 사용한다. 이러한 선택적 사륜구동은 운전자가 보내는 전기적 신호를 Transfer case에서 기계적으로 바꿔서 구동력을 변환시킨다. 본 연구에서는 전기적 신호를 기계적으로 바꿔주기 위해 모터에 감속기를 적용하여 토크를 증대시켜 기능을 수행하였다. 따라서, 본 연구에서는 구동을 변환시켜주기 위해 적용되는 Transfer case내부에 있는 모터에 적용할 수 있는 감속메커니즘을 도출하고 그에 따른 유성기어형태를 적용한 감속비를 최적화하였다. 그리고 도출된 감속비를 토대로 링기어를 공통으로 사용하는 유성기어 2세트를 적용하여 입력축과 출력축이 동일상에서 감속이 진행되는 유성기어 기어치형의 개발 및 Transfer csae 내에 있는 구동변환장치 구동부의 최적화 설계를 진행하였다.

• 한국기계기술학회지
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• 제13권4호
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• pp.37-42
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• 2011

The purpose of this study is to investigate the actual field application of the super-charger for heavy equipment. In this paper, the numerical analysis and performance evaluating experiments were performed. ANSYS CFX program has been used to obtain the solutions for the problems of three-dimensional turbulent air flow in the super-charger. To evaluate the flow performance of the super-charger, the performance test facility and data acquisition system were manufactured. We obtained satisfactory results from CFD analysis and flow experiment.

• 제어로봇시스템학회논문지
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• 제14권3호
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• pp.301-306
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• 2008

Drivers are becoming more fatigued and uncomfortable with increase in traffic density, and this condition can lead to slower reaction time. Consequently, they may face the danger of traffic accidents due to their inability to cope with frequent gear shifting. To reduce this risk, some drivers prefer automatic transmission (AT) over manual transmission (MT). The AT offers more superior drivability and less shifting shock than the MT; therefore, the AT market share has been increasing. The AT is controlled by an electronic control unit (ECU), which provides better shifting performance. The transmission control unit (TCU) is a higher-value-added product, so the companies that have advanced technologies end to evade technology transfer. With more cars gradually using the ECU, the TCU is expected to be faster and more efficient for organic communication and arithmetic processing between the control systems than the l6-bit controller. In this paper, the model of an automatic transmission vehicle using MATLAB/Simulink is developed for the Hardware in-the-Loop (HIL) simulation with a 32-bit embedded system, and also the AT control logic for shifting is developed by using MATLAB/Simulink. The developed AT control logic, transformed automatically by real time workshop toolbox, is loaded to a 32-bit embedded system platform based on Freescale's MPC565. With both vehicle model and 32-bit embedded system platform, we make the HIL simulation system and HIL simulation of AT based on real time operating system (RTOS) is performed. According to the simulation results, the developed HIL simulator will be used for the performance test of embedded system for AT with low cost and effort.

• 한국농공학회지
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• 제17권1호
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• pp.3627-3641
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• 1975

The Government is trying to increase total food grain yield to meet national self sufficiency by means of increasing unit yield as well as extending crop land, and this year he set the target of 321,000 hectare of forest to clear for cropping. This study was carried to investigate the most efficient method of clearing hillock by bulldozer, and successful method to develope yielding potential of newly cleared land in short term. Since the conventional land clearing method is just earth leveling and root removing neglecting top soil treatment, the growth of crop was poor and farmer tends not to care the land. The top-soil-furrowing method is applied through out this study, that is advantageous especially for the land having shallow top soil and low fertility like Korean forest. In this study, various operating method were tried to find out most efficient method separately in connection with the land slope less than 25 percent and over, and several fertilizing methods to develop yielding potential. The results are as follows; 1) For the natural land slope utilization method, applicable to the land having less than 25 percent slope, reverse operating was more efficient than using forward gear of bulldozer. The operating time was 3 hour 32 minutes and 36 seconds using forward gear was 2 hour 32 minutes and 30 seconds for reverse gear operation per 1,000 square meter. 2) Bulldozer having angle blade adjustment needed 7hr 15min. for constructing of terrace per 10a compaire with the one having angle & tilt adjustment needed 6hr 4min for same operations. Specially there is significant difference for operation time of first period (earth cutting) such as bulldozer having angle blade adjustment needed 3hr 56min compaired with the one having angle & tilt adjustment 3hr 59min. In construction of terrace, the bull-dozer having tilting and angle blade adjustment was most suitable and performed efficiently. 3) For the fertilizer application treatment, the grass (Ladino clover) yield in first year was almost same as ordinary field's in the plot applied(N.P.K+lime+manure) while none fertilizer plot showed one tenth of it, and (N.P.K.+lime) applied plot yielded on third. 4) The effect of different land clearing method to yield showed significant difference between each treatment especially in the first year, and the conventional method was the lowest. In the second year, still conventional terracing plot yielded only half of ordinary field while the other plots showed as same as ordinary field's. 5) The downward top soil treatment plot showed most rapid improvement in soil structure during one year physio chemically, it showed increase in pH rate and organic composition, and the soil changed gradually from loam to sand-loam and the moisture content increased against the pF rate, and it gives good condition to grow hay due to the increase of field water capacity with higher available water content. 6) Since the soil of tested area was granite, the rate of soil errosion was increased about 2 to 5 percent influencing in soil structure more sand reducing clay content, and an optimum contour farming method should be prepared as a counter measure of errosion.

• 한국통신학회논문지
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• 제39C권10호
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• pp.920-929
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• 2014

최근 통신, 교통, 의료, 산업시설 등에서 수요가 급증하고 있는 임베디드 시스템은 단순한 임베디드 시스템이 아닌 다양한 임베디드 기기의 동작이 통신을 통해 관찰되고 제어되는 Cyber Physical System(CPS)으로 확장되었다. 또한 구글 글래스, 삼성 갤럭시 기어, 소니 스마트 워치 등의 웨어러블 기기를 활용한 사물인터넷(IoT) 기술활용에 대한 관심이 증가하고 있다. 이러한 상황에서 삼성전자의 스마트홈(Smart Home)과 LG전자의 홈챗(Home Chat)이 잇따라 출시되고 있다. 하지만 이러한 서비스들은 스마트폰과 가전기기간에만 통신이 가능하며 그 이외의 단말과는 통신이 불가능하며 모든 정보는 상업용 포털이 운영하는 글로벌 메시징 서버를 통하여 통신이 이루어진다는 단점이 있다. 본 논문에서는 앞서 언급한 단점을 보완하기 위해 단위공간 기반 실내위치인지망 구축하는 구조를 제안한다. 이를 통해 기기들 및 개개인에 대한 정보가 외부로 유출되는 것을 방지하면서 사물인터넷 채팅을 통해 망 내에 존재하는 모든 단말과의 선택적 통신이 가능하다. 또한 좀 더 범용적인 기기 제어가 가능해지고 개인정보의 외부유출 방지가 가능하다.