• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2464-2472
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• 2011

열차주행이 고속화 되고 콘크리트궤도가 건설되고 있는 가운데 레일 체결장치는 저탄성화로 전달하중, 소음, 진동 등을 저감 하려는 추세이다. 따라서 저탄성패드의 적용은 궤도전체의 내구성과 안정성에 미치는 영향이 크다고 할 수 있다. 본 연구에서는 선행연구에서 다룬 패드스프링계수별 정적해석과 실물반복재하시험에 이어 동적응답해석을 추가적으로 수행하였다. 열차바퀴를 실물로 모델링하여 레일위에서 직접 주행시킴으로서 이 때 발생하는 궤도각부의 변형특성을 비교 분석하여 저탄성패드의 스프링계수에 따라 노반으로 전달되는 하중의 저감 효과를 검토하였다.

• 한국기계가공학회지
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• 제14권6호
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• pp.84-89
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• 2015

The thickness of a stable and economical frame has been designed in order to reduce costs. Therefore, this study applied structural analysis and vibration analysis based on a comparison of the thicknesses of frames. Four types of frames (1mm, 2mm, 3mm, and 5mm) were modeled on a bicycle frame that has a length of 842mm, a width of 100mm, and a height of 400.5mm, and all of these frames generated the stress and maximum deformation amount in the state and around the saddle. The maximum stress shown was 25.732 MPa in 1mm, 11.79 MPa in 2mm, and 8.2015 MPa in 3mm, and the maximum deformation amount shown was 0.063611mm in 1mm, 0.031978mm in 2mm, and 0.022319mm in 3mm. The natural frequency of the frame thicknesses 1mm, 2mm, and 3mm was estimated as within 270 Hz. The critical frequency of conditions of 3mm was the biggest at 118.1Hz compared with the 3-mm model; thus, 3mm was shown to have the most satisfactory resistance.

• Journal of Mechanical Science and Technology
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• 제17권10호
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• pp.1450-1457
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• 2003

Structural integrity of either a passenger car or a light truck is one of the basic requirements for a full vehicle engineering and development program. The results of the vehicle product performance are measured in terms of durability, noise/vibration/harshness (NVH), crashworthiness and passenger safety. The level of performance of a vehicle directly affects the marketability, profitability and, most importantly, the future of the automobile manufacturer. In this study, we used the Virtual Proving Ground (VPG) approach for obtaining the dynamic stress or strain history and distribution. The VPG uses a nonlinear, dynamic, finite element code (LS-DYNA) which expands the application boundary outside classic linear, static assumptions. The VPG approach also uses realistic boundary conditions of tire/road surface interactions. To verify the predicted dynamic stress and fatigue critical region, a single bump run test, road load simulation, and field test have been performed. The prediction results were compared with experimental results, and the feasibility of the integrated life prediction methodology was verified.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.866-867
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• 2011

As part of the green growth, The Green Car has attracted wide attention. Types of the Green Car are Electric Vehicle, Plug-in Hybrid Electric Vehicle, Hybrid Electric Vehicle, Fuel Cell Vehicle and Clean Diesel Vehicle. Of these, The electric vehicle is equipped with the BDU(Battery Disconnecting Unit). BDU is supplying stable battery power and blocking it to protect electrical system of the electric vehicle. The BDU consists of electric components such as current sensor, fuse and pre-charge resistor. These must pass Voltage withstand test, Salt mist test, Thermal shock test, Vibration test and Short-circuit test commonly to verify reliability of the electric components. In addition, The current sensor should be verified whether normal operation. The breaking capacity of fuse should be verified. The durability of pre-charge resistor should be verified by supplying battery power and blocking it repeatedly. The reliability of BDU as well as the electric vehicle is secured by verifying the reliability of electric components. In addition, It will contribute to the acceleration and promotion of Green Car Technology.

• 산업경영시스템학회지
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• 제34권1호
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• pp.90-96
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• 2011

The shock absorber base assembly is one of the parts in the shock absorber equipment that controls the vehicle movement. It absorbs the shock and vibration to guarantee riding stability and comfort. It demands strength, reliability and strict airtightness of the welded section because the shock absorber base assembly is a container which resists pressure and needs durability by being filled with gas and oil. However, the current engineering needs a lot of production time, has a high cost and shows a low production rate. These problem due to the eight production processes, four of which are spot welding, reinforcement welding like metal active welding (MAG), prior process of the base assembly cap and tube for precision and pressing. We will analyze the manufacturing processes of the base assembly and suggest an improved manufacturing method that uses frictional welding. The results will show that the new method of the frictional welding is better than the previous welding technique. Through the use of this concept of frictional welding, the welding conjunction will be strengthened, measurements will be more precise, and the cost and the number of processes will be reduced.

• 소음진동
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• 제9권4호
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• pp.643-651
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• 1999

A brief description of the current technology (contact-start-stop) employed in most of today's hard disk drive is presented. The dynamics and head/disk interactions during a start/stop process are very complicated and no one has been able to accurately model the interactions. Thus, the head/disk interface that meets the start/stop durability and stiction requirements are always developed statistically. In arriving at a solution. many sets of statistical tests are run by varying several parameters. such as, the carbon overcoat thickness. lubricant thickness. disk surface roughness, etc. Consequently, the cost associated III developing an interface could be significant since the outcome is difficult to predict. An alternative method known as Load/Unload technology alters the problem set. such that. the start/stop performance can be designed in a predictable manner. Although this techno¬logy offers superior performance and significantly reduces statistical testing time, it also has some potential problems. However. contrary to the CSS technology. most of the problems can be solved by design and not by trial and error. One critical problem is that of head/disk contacts during the loading and unloading processes. These contact can cause disk and slider damage because the contacts are likely to occur at high disk speeds resulting in large friction forces. Use of glass substrate disks also may present problems if not managed correctly. Due to the low thermal conductivity of glass substrates. any head/disk contacts may result in erasure due to frictional heating of the head/disk interface. In spite of these and other potential problems. the advantage with L/UL system is that these events can be understood. analyzed. and solved in a deterministic manner.

• 한국융합학회논문지
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• 제6권6호
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• pp.279-284
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• 2015

항공기의 추력으로 구동되는 추진축의 회전운동에서 발생되는 진동은 추진축의 수명에 큰 영향을 끼친다. 그리고 회전중 추진축에서 피로파괴가 발생하게 될 시에, 막대한 인명피해를 야기하게 된다. 비행환경에 따라 다양한 회전에 놓이게 되는 추진축에서 떨림이 발생한다. 따라서 이러한 피로파괴가 우려되는 추진축 부위를 본 논문에서는 해석적 연구를 통해 사전에 파악함으로서, 파손방지를 위한 그 내구성이 향상되고 근간된 안전설계를 토대로 융합기술에 접목하여 그 미적인 감각을 나타낼 수 있다.

• 한국정밀공학회지
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• 제28권2호
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• pp.185-192
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• 2011

This study deals with a basic proposal to prove the safety for the exhausted fittings of the hydrogen fuel cell vehicle. First, this study was approached to numerical analysis solving to close the exact boundary condition (Axial, Bending, Lateral) and the second, this study produced the Lateral movement equipment for the vibration. For the numerical analysis, This study was considered with the exact solution of Lateral movement and the resonance effect for durability sample according to fitting positions. The second, This study was made for special equipment for displacement/gas leak and the frequency because the domestic samples were comparing with foreign fitting and foreign fitting for the hydrogen fuel cell vehicle. The result of this study was satisfied with domestic fittings for the basic reference but it need more test because of other situation for hydrogen fuel cell vehicle.

• 한국정밀공학회지
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• 제23권5호
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• pp.177-183
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• 2006

A tape feeder is an important feeding device to supply micro-chips such as 1005 and 0603 components to PCB in SMT process. Traditionally, tape feeding methods using sprocket wheel mechanism has been used for the pickup system of chip-mounters. However, there is growing needs for new feeding mechanism with high accuracy and confidence as electric components are getting much smaller. Thus, recently, a tape feeder using cam-slider mechanism is developed to meet such requirements. The major advantages of developed system are; significantly reduced indexing and backlash errors, slim and compact design, and improved repetitive capacity compared to existing system. In this paper, the performance evaluation criteria for the developed tape feeder are suggested. Stability against induced vibration, positioning accuracy, cycle time, durability and supply error rate are estimated using developed self testers. As a result, the excellence of developed tape feeding mechanism is validated using the effective rating methods.

• 센서학회지
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• 제14권4호
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• pp.237-243
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• 2005

Strain gauge type load cell is used widely as weight sensor. However, it has problems such as noise, power consumption, high cost and big size. Semiconductor type piezoresistive pressure sensor is practically used in recent for low hysteresis, good linearity, small size, light weight and strong on vibration. In this paper, we have fabricated the piezoresistive pressure sensor and packaged the miniature weight sensor. We packaged the miniature weight sensor by flip-chip bonding between die and PCB for durability, because the weight sensor is directly contacted on a physical solid distinct from air and oil pressure. We measured the characteristics of the weight sensor, which had the output of $10{\sim}80$ mV on the weight range of $0{\sim}2$ kg. In the result, we could fabricate the weight sensor with an accuracy of 3 %FSO linearity.