• 대한기계학회논문집A
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• 제34권7호
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• pp.935-941
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• 2010

하나로는 한국에 설치되어 있는 열출력 30MW의 개방 수조형 연구로 이다. 이는 발전로와 달리 원자로에서 발생하는 열을 이용하여 전기를 생산하는 것 대신에 원자로의 노심 온도를 유지하기 위하여 냉각탑을 통해 대기로 이 열을 냉각한다. 냉각탑 월간 점검 중에 냉각탑 4번의 냉각팬 감속기가 기준을 상회하는 고진동을 기록하였다. 본 연구의 목적은 고진동의 원인을 찾아 정상적으로 수리하기 위함이다. 연구 방법은 FFT 스펙트럼 기법을 적용하여 고진동의 원인을 분석하였다. 그 결과 고진동 주파수는 피니언 기어의 고유 진동수의 두 배인 354Hz이었다. 피니언 기어를 점검한 결과 이빨 표면이 깨져 있었다. 깨진 피니언 기어를 제거하고 새것으로 교체한 후에는 감속기는 정상적으로 작동하였다.

• Structural Monitoring and Maintenance
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• 제1권3호
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• pp.249-271
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• 2014

This paper presents a unique study of Structural Health Monitoring (SHM) for the maintenance decision making about a real life movable bridge. The mechanical components of movable bridges are maintained on a scheduled basis. However, it is desired to have a condition-based maintenance by taking advantage of SHM. The main objective is to track the operation of a gearbox and a rack-pinion/open gear assembly, which are critical parts of bascule type movable bridges. Maintenance needs that may lead to major damage to these components needs to be identified and diagnosed timely since an early detection of faults may help avoid unexpected bridge closures or costly repairs. The fault prediction of the gearbox and rack-pinion/open gear is carried out using two types of Artificial Neural Networks (ANNs): 1) Multi-Layer Perceptron Neural Networks (MLP-NNs) and 2) Fuzzy Neural Networks (FNNs). Monitoring data is collected during regular opening and closing of the bridge as well as during artificially induced reversible damage conditions. Several statistical parameters are extracted from the time-domain vibration signals as characteristic features to be fed to the ANNs for constructing the MLP-NNs and FNNs independently. The required training and testing sets are obtained by processing the acceleration data for both damaged and undamaged condition of the aforementioned mechanical components. The performances of the developed ANNs are first evaluated using unseen test sets. Second, the selected networks are used for long-term condition evaluation of the rack-pinion/open gear of the movable bridge. It is shown that the vibration monitoring data with selected statistical parameters and particular network architectures give successful results to predict the undamaged and damaged condition of the bridge. It is also observed that the MLP-NNs performed better than the FNNs in the presented case. The successful results indicate that ANNs are promising tools for maintenance monitoring of movable bridge components and it is also shown that the ANN results can be employed in simple approach for day-to-day operation and maintenance of movable bridges.

• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.106-111
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• 2024

A triboelectric nanogenerator is a promising energy harvester operated by the combined mechanism of electrostatic induction and contact electrification. It has attracting attention as eco-friendly and sustainable energy generators by harvesting wasting mechanical energies. However, the power generated in the natural environment is accompanied by low frequencies, so that the output power under such input conditions is normally insufficient amount for a variety of industrial applications. In this study, we introduce a non-contact rotational triboelectric nanogenerator using pedaling and gear systems (called by P-TENG), which has a mechanism that produces high power by using rack gear and pinion gear when a large force by a pedal is given. We design the system can rotate the shaft to which the rotor is connected through the conversion of vertical motion to rotational motion between the rack gear and the pinion gear. Furthermore, the system controls the one directional rotation due to the engagement rotation of the two pinion gears and the one-way needle roller bearing. The TENG with a 2 mm gap between the rotor and the stator produces about the power of 200 ㎼ and turns on 82 LEDs under the condition of 800 rpm. We expect that P-TENG can be used in a variety of applications such as operating portable electronics or sterilizing contaminated water.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.711-712
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.715-716
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.1245-1246
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• 2013

• Tribology and Lubricants
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• 제20권5호
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• pp.272-277
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• 2004

This study deals with the friction and wear characteristics of C-N coated spur gear. The PSII apparatus was built and a SCM415 test piece and test gear with steel substrate was treated with carbon nitrogen by this apparatus. The composition and structure of the surface layer were analyzed and compared with that of PVD coated TiN layer. It was found that both of friction coefficient of C-N coating and TiN coating decreased with increasing load, however, C-N coating showed relatively lower friction coefficient than that of TiN coating. We was investigated the effect of C-N coating on hardness, friction and wear. The TiN coated gear showed a more serious friction phenomena than that of C-N coated gear. It was considered that coating of TiN, which was conducted at a vacuum chamber at about 500$^{\circ}C$, results in a tempering of base material that causes microstructural change, which in turn resulted in decreasing of hardness. The C-N coated gear and pinion had higher wear resistance that of TiN coated gear and pinion. C-N coating significantly improved the friction and wear resistance of the gear.

• 대한기계학회논문집A
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• 제29권2호
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• pp.239-246
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• 2005

A rotor dynamic analysis is implemented to confirm the vibration stability of the high speed centrifugal chiller coupled with gear system. As the rotating speed of the centrifugal chiller under investigation is increased up to 17605rpm at the pinion rotating part, the bearing instability is getting higher and, furthermore, the rotor-bearing system might experience a few critical speed which lead to system failure due to the excessive vibration. In this study, considering the loading capacity and stability conditions, offset journal bearings are adopted for the pinion rotating system and general cylindrical bearings are used for motor part. From the modal analysis, the system is found to be stable as the critical damping ratio which shows the damping characteristics of the system are positive over all operating ranges, and in addition, the synchronous rotating frequency does not come across with any whirl natural frequency. From these results the authors confirm the vibration stability of the rotor-bearing system suggested in this study.

• 대한기계학회논문집
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• 제15권1호
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• pp.154-162
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• 1991

본 연구에서는 내치차의 절삭가공에서 발생하는 치형오차를 대상으로 이에 영 향을 미치는 제반 조건 중, 커터의 이론적인 인벌류트 치형으로부터의 편차, 커터와 내치차의 잇수에 의한 간섭, 창성과정(generating process)중 원주방향 이송과 같은 가공조건이 기어의 치형오차에 미치는 영향을 분석하고 이를 최소로 하는 조건을 유도 하여 양질의 내치차 생산에 기여 하고자 한다.

• 한국생산제조학회지
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• 제19권1호
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• pp.134-139
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• 2010

In this study, we developed the gear type vane damper replacing the link type through gear design using Finite Element Analysis(FEA). FEA about the pinion and the vane shaft in the boss of gear type damper for quality improvement was accomplished. We analyzed fluid flow according to angular displacement. Catched the problem of the torque and backlash bring to the pinion as structure improvement of the forced draft fan(FD FAN). Finally, we compared the gear driving result with simulation. It is the objective of the present study to identify a nonlinear flow rate control of gear type vane damper and to suggest a damper shape with a linear flow rate control. This study is related to the development of gear type vane damper change link type in forced draft fan.