• 열처리공학회지
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• 제24권1호
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• pp.10-15
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• 2011

Recently, renewable energy sources such as wind turbine, solar cell are interested in preventing global warming which is caused by the consumption of fossil fuel. SCM440(H) and SNCM439 have been used in the major components of the wind turbine gear because of excellent mechanical properties. In the present study, the heat treated mechanical properties of SCM440(H) and SNCM439 with 150 mm diameter were compared with those with 25 mm diameter which is generally accepted material for structural application. Heat treated SCM440(H) showed better mechanical properties such as tensile strength, hardness and impact absorbed energy compared with those in SNCM439. Hardenss value between as-quenched and as-quenched followed by tempering showed big difference in SNCM439, however the difference in SCM440(H) was relatively small. Heat treated mechanical properties of the alloys with 25 mm diameter were more uniform value than those with 150 mm diameter.

• 한국정밀공학회지
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• 제33권8호
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• pp.623-628
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• 2016

This article describes the determination of the dynamic stability for a heavy press, particularly considering rotational speed. A finite element model of the driving parts for the heavy press was generated. We also applied boundary conditions and dynamic loads considering the driving conditions. Modal analysis was conducted using the finite element construction model. Therefore, no resonance was identified with the comparison between the results of the modal analysis and vibration excitation frequency by the gear tooth. In addition, the stress distribution of the driving parts for press was determined using transient analysis. As compared to the yield strength of the material, the dynamic stability the heavy press was confirmed.

• 한국기계가공학회지
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• 제18권6호
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• pp.76-81
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• 2019

In the mold-manufacturing field, various methods of advanced production technology are being used in the production of industrial-grade gear pulleys. Among the current methods are injection molding, hoop molding, insight molding, two-material molding, compound-mold molding, as well as engineering plastic mold. Currently, casting pulleys are inexpensive because they are produced in small quantities. However, they produce complications during the manufacturing process, are very unreasonable for mass production, and are disadvantageous in cost competitiveness. Pulleys are divided into hundreds of kinds and thousands of kinds, so the production methods vary. As these pulleys are made of a single material by a casting and welding method, they are not manufactured using injection molds consisting of different materials. In this research, pulleys, shafts, and reinforced plastic materials were incorporated using ANSYS software, and a low-cost, lightweight technology was applied for trial production with optimum design and extrusion technology.

• Advances in nano research
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• 제16권4호
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• pp.365-374
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• 2024

This study delves into the significant impact of integrating nanomaterials, specifically carbon and graphene nanoparticles, into the polymer matrix of aluminum alloy 356, utilizing the vortex casting technique, with the aim of improving the mechanical properties of table tennis equipment. Athletes and their coaching teams have long been on a quest for high-performance sports gear, recognizing its pivotal role in unlocking the full potential of players. The dedication of engineers to craft designs, select materials with precision, and uphold stringent testing standards reflects the commitment to meeting the demands of the sporting world. Yet, to remain at the forefront, sports engineering must continually align with contemporary technologies, and nanotechnology has emerged as a transformative force in this regard. This study not only underscores the meticulous efforts in material integration but also highlights the remarkable strides made possible by nanotechnology. Aluminum nanocomposites, particularly, showcase a groundbreaking fusion of exceptional strength and reduced weight, marking a notable achievement in sports equipment innovation. The research outcomes are compelling, revealing a substantial enhancement in the mechanical performance of the sports structures under scrutiny. This promising development hints at a potential paradigm shift in the manufacturing of sports equipment, promising a new era of elevated athlete performance and enhanced safety during the rigors of physical education training. This study stands as a testament to the tangible impact of nanotechnology on the ever-evolving landscape of sports equipment.

• 대한교통학회지
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• 제22권5호
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• pp.75-87
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• 2004

우리나라 해안지역은 강풍의 빈도가 높고 세기도 크지만 아직까지 바람을 고려한 적정속도를 안내하는 시스템은 전무한 상태이다. 강풍이 부는 곳에서의 무리한 주행은 핸들 조작의 어려움으로 인한 사고 위험과 풍속을 고려하지 않은 과속으로 인한 전복사고 등의 위험이 크다. 이러한 측면에서 바람 잦은 곳 중 주요지점에 기상정보센서(WIS:Weather Information Sensor)를 설치하고 이로부터 실시간으로 측정된 기상정보를 바탕으로 차량의 구동력과 주행저항의 크기를 극대화하는 적정속도를 VMS를 통하여 제공하는 방안이 필요하다. 목포시에 건설예정인 목포대교를 대상으로 풍속별 적정 속도를 산출한 결과, 연중 평균 풍향인 남풍일 경우 교량의 입지(정남-북)에 따라 남측으로 주행하는 차량에 대하여 풍속이 8m/h이상일 경우에는 평상시와 달리 돌풍을 대비한 여유구동력이 큰 60km/h의 속도를 안내해 주는 것이 바람직 한 것으로 나타났다. 또한 2003년도에 발생한 태풍 매미 시 목포시의 풍속인 18m/s 일 경우 시속 40km/s에서의 주행저항은 1131N으로써, 이미 변속 4단에서의 구동력(약 1054N)으로는 극복할 수 없으므로 3단 이하에서 변속을 하여야 하며, 이때의 적정속도는 주행저항과 구동력간의 차이가 가장 크게 발생하는 40km/h인 것으로 분석되었다.

• 수산해양기술연구
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• 제47권3호
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• pp.173-182
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• 2011

The purpose of this paper is to provide useful information for fishermen in the manner of investigation a sinking speed of current type tuna longline gear at the North Pacific Ocean as a new developed tuna longline fishing ground. The sinking depth of mainline in connection with different basket was investigated. The experiments were also performed with different materials such as Supermansen (i.e., PE) and Hitech (i.e., PA) for the mainline to investigate the sinking depth of mainline and hooks. Furthermore, the relation between the sinking depth of hooks and catches are investigated also. The sinking depth of mainline at the first and the last shooting basket shows deeper than that of middle part of a basket due to reduced shortening ratio. The sinking depth of mainline and hook with Hitech material shows more shallow than that of Supermanse material, even the Hitech case was designed to sink deeper than that of Supermanse case. The highest catches arise at the middle part basket as the hook number 7 with around 248m sinking depth. From the results, longline with Hitech material is needed to increase the sinking force for reaching the relevant sinking depth. Moreover, the current strength at the North Pacific Ocean will be considered for further commercial fishing.

• 한국소음진동공학회논문집
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• 제22권4호
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• pp.318-327
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• 2012

The operating sound radiated from a laser printer includes tonal noise components caused by the rotating mechanical parts such as gear, shaft, motor, fan, etc. The negative effects of the tonal noise components need to be considered in the process of developing a sound quality index for the quantitative evaluation of the emotional satisfaction in terms of psycho-acoustics. However, in a previous paper, it was confirmed that the Aures tonality did not have enough correlation with the results of jury evaluation. The sound quality index based on loudness, articulation index, fluctuation strength has a little problem in considering the effects of rotating mechanical parts on the sound quality. In this paper, to solve the tonality evaluation problem, the calculation algorithm of Aures tonality was investigated in detail to find the cause of decreasing the correlation. The new tonality evaluation model was proposed by modifying and optimizing the masking effect, loudness ratio, and shape of weighting curve based on the basic algorithm of Aures tonality, and applied to two kinds of operating sound groups in order to verify the usefulness of proposed model. As a result, it is confirmed that the proposed tonality evaluation model has enough correlation and usefulness for expressing the tonalness in the operating sounds of laser printers. In the following paper, this results will be used to model the sound quality index as the input data by using the classification algorithm.

• 대한정형외과스포츠의학회지
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• 제7권2호
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• pp.67-74
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• 2008

반복적으로 던지는 동작은 주관절에 심한 기계적인 스트레스를 주며, 주된 기전은 외반력이며 그 결과 내측 인장력과 외측 압박력, 후방부의 충돌현상이 발생한다. 성장기나 청년기에 지속적인 스트레스는 주관절에 해부학적 변화를 유발할 수 있다는 위험성을 운동선수와 가족, 코치들은 반드시 잘 이해하고 있어야 한다. 스포츠와 관련된 주관절 손상을 막기 위하여 적절한 운동법 교육, 워밍업, 의학적 전문 지식, 보호 장구 등이 필요하다. 또한 손상 예방과 재활은 적절한 투구 동작, 근력 강화, 견갑골에 대한 조절, 관절 운동 범위의 적절한 유지가 필수적이다.

• 한국수산과학회지
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• 제23권3호
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• pp.245-252
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• 1990

한국 남해에 분포하는 요각류와 모악류의 수괴 지표성종으로써의 가치를 이용하여 수괴의 특성을 구명하기 위하여 1988년 2, 4 및 8월에 한국 남해안28개 정점에서 NORPAC net를 이용하여 수직 채집한 동물성 부유생물을 분석하였다. 요각류와 모악류중 한국 남해의 주요 수괴 지표성종으로써 Acartia clausi, Centropages abdominalis는 연안 저온성종으로, Sagitta crassa는 연안성종으로, Pleuromamma gracilis, Undinula darwini, Calocalanus plumulosus, Calanopia elliptica와 Sagitta enflata는 난류 외양성종으로, 그리고 Temora discaudata, Centropages furcatus는 난류성종인 것으로 밝혀졌으며, 이들 종의 분포와 수심 30m에서 수온과를 비교 분석하였다. 또한 Cluster분석을 실시하여 수괴의 계절적 변동을 파악하였다. 2월에는 크게 2개의 해역으로 남해 연안 해역과 남해 외양역으로 대별되었으며 4월에는 크게 4개의 해역으로 대별되었다. 8월에는 크게 3개의 해역으로 대별되었으며, 쓰시마난류가 연안으로 강하게 영향을 미침을 나타내었다.

• International Journal of Advanced Culture Technology
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• 제7권1호
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• pp.231-236
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• 2019

Background/Objectives: This paper proposes a dual mode feedback-controlled cycling system for children with spastic cerebral palsy to rehabilitate upper extremities. Repetitive upper limb exercise in this therapy aims to both reduce and analyze the abnormal torque patterns of arm movements in three- dimensional space. Methods/Statistical analysis: We designed an exercycle robot which consists of a BLDC motor, a torque sensor, a bevel gear and bearings. Mechanical structures are customized for children of age between 7~13 years old and induces reaching and pulling task in a symmetric circulation. The shafts and external frames were designed and printed using 3D printer. While the child performs active/passive exercise, angular position, angular velocity, and relative torque of the pedal shaft are measured and displayed in real time. Findings: Experiment was designed to observe the features of a cerebral palsy child's exercise. Two children with bilateral spastic cerebral palsy participated in the experiment and conducted an active exercise at normal speed for 3 sets, 15 seconds for each. As the pedal reached 90 degrees and 270 degrees, the subject showed minimum torque, in which the child showed difficulty in the pulling task of the cycle. The passive exercise assisted the child to maintain a relatively constant torque while visually observing the movement patterns. Using two types of exercise enabled the child to overcome the abnormal torque measured in the active data by performing the passive exercise. Thus, this system has advantage not only in allowing the child to perform the difficult task, which may contribute in improving the muscle strength and endurance and reducing the spasticity but also provide customizable system according to the child's motion characteristic. Improvements/Applications: Further study is needed to observe how passive exercise influences the movement characteristics of an active motion and how customized experiment settings can optimize the effect of pediatric rehabilitation for spastic cerebral palsy.