• 한국생산제조학회지
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• 제21권1호
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• pp.51-57
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• 2012

This study investigates structural and fatigue analyses at bicycle pedal. Maximum deformation at model 1 is 2 times as much as model 2 at static analysis. Models 1 and 2 have the possibility of the weakest strength at the part of contact with chain gear. Among the cases of nonuniform fatigue loads at Models 1 and 2, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^4$ MPa and the amplitude stress of 0 to $10^4$ MPa, the possibility of maximum damage becomes 4%. This stress state can be shown with 5 to 7 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The analysis result of this study can be effectively utilized with the safe design of pedal.

• Journal of Biosystems Engineering
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• 제36권1호
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• pp.9-14
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• 2011

This study was carried out to develop a vine crusher for harvesting sweet potato. The experimental two-row vine crusher attachable to agricultural tractor composed of vine crushing part with frail type vine crushing blades and vine lifting blades, power transmission part with chain and gear transmission mechanism, crushing height control part with two control wheels and manual levers, and implement frames, was designed and fabricated. And this vine crushing performance was also analyzed. From vine crushing tests, backward travel direction (i.e., rotational direction of the vine crushing blades) showed better vine crushing performance than forward travel direction. Crushing ratio of remained vine was increased, and length of remained vine and length of crushed vine were decreased as working speed was decreased and rotational speed of vine crushing blades was increased. At a working speed of 0.27 m/s and rotational speed of vine crushing blades of 800 rpm, crushing ratio of remained vine was 98%, length of remained vine was 104 mm, and length of crushed vine was 327 mm. But, when crushing vine on irregular ridges, vines and mulching vinyl were wound in the vine crushing part. Therefore, change of location of power transmission chain mechanism, and an automatic control device for controlling crushing height were needed.

• Journal of Biosystems Engineering
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• 제25권4호
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• pp.257-264
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• 2000

A tractor attached TMR(model 430) mixer has been developed in a previous study. However, the mixer was found to be improved through field applications in its capacity, manufacturing cost, ergonomic design and power-train requirement. The TMR mixer was modified into a model TMR500, approved by Institute of Agricultural Mechanization, as follows : 1. Roughage cutting system was seperated from the mixer, resulting in the 33% reduction of manufacturing cost. 2. Enlarged hopper capacity enabled to feed 60 heads at a batch. 3. Hydraulically controlled gate system saved ergonomic man power. 4. Power transmission system was changed from a chain-sprocket system(27:1) to the gear-train reduction system(38.6:1) to satisfy the recommended use of 540rpm PTO input.

• 대한안전경영과학회지
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• 제20권4호
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• pp.1-6
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• 2018

Recently, bicycle has means of effective healthy transportation, and riding the bicycles is considered as popular recreational and sporting activities. Also, the saddle, steering system, driving device and braking device are researched briskly because of consumer's need for driving performance and comfort. Especially, the importance of a cassette responsible for transmission function by transmitting power to the drive shaft through the chain is very focused. The writer conducted structural analysis for the sprocket of each level using the ANSYS widely used for the analysis. Speed shifting performance was enhanced by minimization / simplification of shifting point through a sort of tooth profile of the cassette. By partitioning a clear value type and other shifting point, it has been modified to enable smooth speed-shifting. In addition, as titanium precision forming process, this study studied the molding technique by blanking and dies forging for mass production of the cassette. so it could be expected that the entire drive train would utilize that in the future. The stamping process capability for thin materials for the mass production of the sprockets is applicable to producing automobile parts, so lightweight component production is likely to be possible through that, for the safety of driving.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.162-169
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• 2000

This study was carried out to develop a continuously variable-speed transmission(CVT) for agricultural tractor. A full-toroidal CVT mechanism with four discs and six rollers was selected as a device for changing speed ratio continuously. In the step of system layout design, the sizes of roller cylinders and end-load cylinder, which were critical factors for controlling the variator, were designed. Also the control pressure range was designed to limit the contact pressure of variator. In order to make the maximum speed of vehicle as 30km/h, the planetary gear and the six pairs of gears were designed. Also the hydraulic clutch, silent chain, hydraulic manifold and electronic controller were designed. After the design, a prototype with CVT controller was developed and tested. The speed of vehicle was changed continuously to the speed set by driver and the settling time was about 0.52 second at the step-response test (reduction ratio of variator 2.0 to 1.0), which was acceptable as a response time for working with tractor.

• 한국수산과학회지
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• 제56권3호
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• pp.341-346
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• 2023

This study aimed to suggest an alternative income generation (AIG) for local artisanal fisheries communities in the southern coastal area of Bangladesh, which is vulnerable to climate change. To analyze the problems of local artisanal fisheries caused by climate change, field surveys and in-depth interviews with fishermen and government officials were conducted. Livelihood risk factor (LRF) in the marine fishing sector included reduction of fishing days and fish production and damage to fishing vessels and fishing gear due to cyclone and sea-level rise. LRF in the aquaculture sector included cultured fish escape, reduction of aquaculture production, and water pollution due to Monsoon flood. A common challenge for two sectors was high interest rate on commercial loans. Small-scale tank aquaculture is recommended as AIG for securing income of artisanal fisheries communities. In the early stages of dissemination of small-scale tank aquaculture technology, it is necessary to prevent fishermen from struggling to repay high-interest rate loans through technology transfer and facility support by official development assistance. The aquaculture training center, along with the technical education, will also contribute toward expansion of local distribution network and marketing support to establish a value chain for local artisanal fisheries communities.

• 한국산업융합학회 논문집
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• 제26권6_3호
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• pp.1305-1314
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• 2023

The global ship repair and modification market is expected to grow up to approximately $ 30 billion by 2025. Korea's shipbuilding industry is leading the world grounded on its international competitiveness in design and production technology. The reality, however, is that the ship repair and modification industry is centered on Gyeongnam, and there are only two to three ship repair workplaces that can repair large ships. Therefore, domestic ship repair companies target small and medium-sized ships mainly. This is because there are few workplaces equipped with a large dock in which large ships like LNG ships can be inspected regularly or repaired, complaints are severe for environmental problems, and related environmental regulations are so strict that it is very hard to obtain government approval for the extension of ship repair and modification workplaces or the opening of new shipbuilding sites. Besides, on account of the workers' high wages, few experts related, and higher ship repair price compared to that of Southeast Asia, most of the volume of repairing large ships including domestic LNG ships is being lost to Southeast Asian or Chinese markets. In this study, the work process and pre-work preparation process for ship hull (winch, windlass, hatch cover, ramp door, cargo gear, anchor chain) repair were analyzed and presented to foster domestic ship repair experts and revitalize related industries.

• 수산해양기술연구
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• 제36권1호
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• pp.45-53
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• 2000

수산시설용 그물감 재료로 많이 사용되고 있는 PE 및 나일론과 신소재섬유로 구성된 Hi-PE 그물실의 내후성 기구를 파악하기 위하여 그물실에 인공광원을 조사한 후 시간의 경과에 따른 그물실 표면의 형태적 변화와 밀도 및 광각X선 회절 측정을 실시하였으며, 이들 결과를 인장시험에 의한 기계적 물성 특성과 비교\ulcorner고찰하였다. 실험의 결과를 요약하면 다음과 같다. 1. 그물실 표면의 형태적 변화는 염색 처리된 PE와 나일론 그물실의 경우에는 표면에 안료가 석출되었을 뿐 균열은 나타나지 않았으나, 미처리된 Hi-PE 그물실의 경우 자외선 etching에 따른 균열의 현저한 증가를 확인할 수 있었다. 2. 그물실의 분자 충진 밀도의 경우, 염색된 PE 및 나일론 그물실의 경우에는 노출시간이 증가함에 따라 큰 변화는 없었으나, Hi-PE 그물실의 경우에는 분자사슬의 재배열과 chain scission 등의 영향에 의해 밀도가 증가하였다. 3. 세 그물실 모두 회절 피크의 2$\theta$에는 큰 변화가 없는 것으로 보아 결정구조의 근본적인 변화는 없다고 생각할 수 있다. 4. 잔여 강도는 염색처리된 PE 및 나일론 그물실에서 각각 90.8%와 75.3%로 높게 나타났으나, 미처리된 Hi-PE 그물실에서는 68.3%로 가장 작았으며, 이는 전자현미경에 의해 촬영된 그물실 표면의 형태적 변화와도 잘 일치하고 있다.

• 에너지공학
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• 제23권1호
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• pp.46-57
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• 2014

본 논문은 한국 풍력산업의 부가가치 창출구조가 선순환을 나타내고 있는지를 풍력기업 내 가치사슬과 풍력산업 내 가치시스템을 통해 분석하고 있다. 연구 방법은 한국 풍력기업을 대상으로 한 설문조사 를 통해 연구개발-생산-이익률 등에 걸친 가치사슬 내 공정 간 인과관계에 대한 회귀분석을 활용하였다. 기업 내 가치사슬 분석 결과, 한국 풍력기업에서 정부의 연구개발 지원은 기업의 연구개발 투자 증가에, 기업의 연구개발 투자 증가는 기업의 연구개발 성과 증가에, 기업의 연구개발 성과 증가는 기업의 생산량 증가에 연쇄적으로 긍정적인 영향을 미치고 있는 것으로 분석되었다. 그러나 생산량 증가가 생산비용의 감소로 이어지지 못하고 경상이익률의 증가에는 기여하지 못한 것으로 분석되었다. 또한, 경상이익률의 증가가 생산량의 증가에는 기여하나, 기업의 연구개발투자 증가에는 기여하지 못하고 있어 가치사슬의 선순환구조가 취약한 것으로 분석되었다. 산업 내 가치시스템은 로터 블레이드, 기어박스, 발전기 등 시스템 그룹과 타워 등 구조물 그룹 상호 간에 정부의 연구개발 지원과 기업의 연구개발투자, 연구개발 성과, 매출액 대비 경상이익률 등에 있어서는 긍정적인 영향을 미치고 있는 것으로 분석되었다. 그러나 생산량과 생산비용 등에서는 상호 간에 긍정적인 효과를 미치지 못하고 있는 것으로 분석되어 산업생태계가 완성되어 있지 못한 것으로 나타났다. 이러한 실증분석의 결과로부터 국내 풍력기업의 공정 간 부가가치의 선순환 구조와 산업생태계를 구축하기 위해서는 규모의 경제효과를 달성하고 경상이익률 증가가 연구개발투자 증가를 유발할 수 있도록 연구개발지원정책을 강화할 필요가 있다. 또한, 한국 풍력산업 내 가치시스템의 원활한 작동을 위해 생태계 정립을 촉진하는 정책을 추진할 필요가 있다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권1호
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• pp.20-32
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• 2018

Purpose: The purpose of this study is to set up an anomaly detection criteria for sensor data coming from a motorcycle. Methods: Five sensor values for accelerator pedal, engine rpm, transmission rpm, gear and speed are obtained every 0.02 second from a motorcycle. Exploratory data analysis is used to find any pattern in the data. Traditional process control methods such as X control chart and time series models are fitted to find any anomaly behavior in the data. Finally unsupervised learning algorithm such as k-means clustering is used to find any anomaly spot in the sensor data. Results: According to exploratory data analysis, the distribution of accelerator pedal sensor values is very much skewed to the left. The motorcycle seemed to have been driven in a city at speed less than 45 kilometers per hour. Traditional process control charts such as X control chart fail due to severe autocorrelation in each sensor data. However, ARIMA model found three abnormal points where they are beyond 2 sigma limits in the control chart. We applied a copula based Markov chain to perform statistical process control for correlated observations. Copula based Markov model found anomaly behavior in the similar places as ARIMA model. In an unsupervised learning algorithm, large sensor values get subdivided into two, three, and four disjoint regions. So extreme sensor values are the ones that need to be tracked down for any sign of anomaly behavior in the sensor values. Conclusion: Exploratory data analysis is useful to find any pattern in the sensor data. Process control chart using ARIMA and Joe's copula based Markov model also give warnings near similar places in the data. Unsupervised learning algorithm shows us that the extreme sensor values are the ones that need to be tracked down for any sign of anomaly behavior.