• 한국자동차공학회논문집
• /
• 제5권1호
• /
• pp.216-216
• /
• 1997

We developed the durability estimation and design systems to minimize the volume, considering the durability, efficiency, and design requirements of worm gears. That is, we consider each kind of factors affecting on durability on the basis of AGMA Standard for the cylindrical and double-enveloping worm gears. We also estimate input power on the basis of wear and durability, bending strength and deflection of worm shaft, and we developed the durability estimation and design systems of power transmission worm gears introducing the optimal design method on the personal computer to be easily used in field. Also, we developed a method which converts the design variables obtained from the optimal design method to integer values(number of worm threads, number of worm threads, number of worm wheel teeth, etc.,) to be used in real design and production. The developed durability estimation and design method can be easily applied to the design of worm gears used as power transmission devices in machineries and is expected to be used for weight minimization of worm gear unit.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
• /
• pp.659-664
• /
• 2000

In this paper, We have discussed on the modeling of machined outer geometry which was established for the case of round shape machining, also the effects of externally machined profile are analyzed and its modeling realiability was verified by the experiments of roundness testing, especially in lathe operation. In this study, we established harmonic geometric model with the parameter harmonic function. In general, we can calculate the theoretical roundness profile with arbitrary multilobe parameter. But in real experiments, only 2-5 lobe profile was frequently measured. the most frequently ones are 3 and 5 lobe profile in experiments. With this results, we can predict that these results may be applies to round shape machining such as turning, drilling, boring, ball screw and cylindrical grinding operation in bearing and shaft making operation with the same method. In this study, simulation and experimental work were performed to show the profile behaviors. we can apply these new modeling method in real process for the prediction of part profile behaviors machined such as in round shape machining operation.

• 한국지반공학회논문집
• /
• 제24권12호
• /
• pp.13-22
• /
• 2008

지반조건과 말뚝의 테이퍼각도가 태야퍼말뚝의 지지력에 미치는 영향을 조사하기 위해서 원통형말뚝과 테이퍼각도가 다른 두 개의 메이퍼딸뚝을 이용해서 모형말뚝재하시험을 수행하였다. 시험결과에 띠르면 지반의 평균응력과 상대밀도가 커지면 테이퍼말뚝의 단위 선단지지력은 증가하였고, 말뚝의 테이퍼각도가 커집에 따라 느슨한 지반에서는 단위 선단지지력은 증가하였으나 조밀한 지반에서는 단위 선단지지력이 반대로 감소하였다. 그리고 테이퍼말뚝의 단위 주면마찰력은 지반의 수평 및 연직응력과 상대밀도, 말뚝의 테이퍼각도가 커짐에 따라 증가하는 것으로 나타났다. 한편, 모형말뚝재하시험의 결과에 근거해서 형상계수를 표함한 테이퍼말뚝의 지지력 산정식을 제안하였고, 이 제안식에서는 지반조건과 테이퍼각도가 말뚝의 지지력에 미치는 영향이 고려되였다. 제안한 지지력 산정식에 대한 정확도를 검증하기 위해서 점토질 모래지반에 설치된 중간규모의 원통형말뚝과 테이퍼말뚝에 대한 현장재하시험이 실시되었고, 이때 측정된 지지력이 제안식에서 얻은 예측치와 비교되었다. 그 결과 제안된 지지력 산정식은 테이퍼말뚝의 지지력을 비교적 정확하게 예측하는 것으로 나타났다.

• 한국전기전자재료학회논문지
• /
• 제25권12호
• /
• pp.943-948
• /
• 2012

A new water energy harvester module, which is composed of piezoelectric bimorph cantilevers, harvesting circuit and a shaft with 16 impellers at a center axis, was fabricated for energy harvesting application. High energy density $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt% $Nb_2O_5$ (PZT-CN) thick film obtained by tape casting method was used for the bimorph cantilever. The PZT-CN bimorph cantilever with a proof mass of 49 g exhibited extremely high output power of 22.5 mW (24 $mW//cm^3$) at resonance frequency of 11 Hz. In addition, the fabricated water energy harvester has a cylindrical structure with 48 bimorph cantilevers clamped at inner surface. A significantly high output power of 433 mW was obtained at a rotation speed of 120 rpm with a resistive load of $500{\Omega}$ for the water energy harvester.

• 한국태양에너지학회 논문집
• /
• 제34권2호
• /
• pp.60-65
• /
• 2014

A meteorological(met) tower is the first structure installed during the planning stages of offshore wind farm. The purpose of this paper is to design the met tower with tripod bucket type support structure and to install the sensors. The support structure consist of a central steel shaft connected to three cylindrical steel suction buckets which is more cheaper than monopile or jacket type. And the remote wind condition sensors and marine monitoring equipment, including adcp, pressure type tide gauge, wave height sensors, and scour sensors, remote power supply are installed. The manufactured met tower constructed on sea area which is in front of Gasa island. All of functions of met tower showed normal operation conditions and the wind data got by remote data collection system successfully.

• 한국정밀공학회지
• /
• 제30권11호
• /
• pp.1129-1137
• /
• 2013

We report a centerless grinding machine which can perform multi-function with 600 mm wide grinding wheels. By increasing manufacturing area, long workpiece such as camshaft and steering shaft, is allowed to grind more quickly, compared with cylindrical grinding system. In this paper, the design of centerless grinding machine puts emphasis on symmetry to exploit the thermal stability. Results of finite element analysis shows that the difference of the structural deflection in the front and rear guideways is less than $1.5{\mu}m$ due to symmetric design. The difference is less than $3.0{\mu}m$, even though the thermal deformation is considered. According to the performance evaluation, the radial error motion of the G/W spindle, which is measured by applying Donaldson Ball Reversal, is about 1.1${\mu}m$. The yaw error of the G/W slide is improved from 2.1 arcsec to 0.5 arcsec by readjusting the slide preload and ball screw.

• Journal of Acupuncture Research
• /
• 제36권1호
• /
• pp.38-44
• /
• 2019

Background: The phrase "Nine Needles" refers to the 9 types of acupuncture needles describing their shapes, sizes, and uses in Huangdi's Internal Classic Ling-shu. The aim of this study was to present 3D illustrations of the "Nine Types of Needles" based on Huangdi's Internal classic Ling-shu, taking into consideration the conformation and application of the Nine Needles. Methods: Sketches of the "Nine Needles" were based on references to those needles cited in Huangdi's Internal Classic Ling-shu, the Great Compendium of Acupuncture and Moxibustion, and the Golden Mirror of Medicine. The computer programs Creo 3.0, Keyshot 5, Adobe Photoshop CS5, and Adobe Illustrator CS5 were used for 3D modelling and visualization. Results: Based on a review of Huangdi's Internal Classic Ling-shu, illustrations of the Spade needle, Round-Pointed needle, Pressure needle, Sharp-Edged needle, Sword-Shaped needle, Round-Sharp needle, Fine needle, Long needle, and Large needle, 3D models were created. The Spade needle had a sharp, large head, the Round-Pointed needle had an egg-shaped tip, and the Pressure needle had a blunt head like a grain of millet. The Sharp-Edged needle had a sharp blade with a triangular edge for bloodletting. The Sword-Shaped needle resembled a sword. The Round-Sharp needle resembled a horse's tail. The Fine needle and the Long needle had sharp points and thin bodies. The Large needle had a cylindrical shaft and rounded tip. Conclusion: This study demonstrated that 3D illustrations could be generated for the Nine Needles according to the descriptions and figures provided in the ancient literature.

• 항공우주시스템공학회지
• /
• 제18권3호
• /
• pp.17-26
• /
• 2024

항공기 엔진은 비행 중 고온, 고압과 터빈 축의 회전으로 인한 응력이 발생한다. 이러한 하중으로 인해 구조 내/외부에 미세한 균열이 발생할 수 있다. 이는 구조적 결함으로 이어져 부품의 수명에 악영향을 줄 수 있다. 이러한 현상을 사전에 방지하고자 균열에 대한 유한요소해석이 진행된다. 하지만 이 과정은 반복적인 균열 모델링이 이루어져 많은 시간과 노력을 수반한다. 그러므로 본 논문에서는 유한요소모델 기반의 균열 모델링 기법을 개발하였다. 균열 모델링에는 점 간의 연결에 제한을 가지고 공간을 삼각 분할하는 Constrained Delaunay Triangulation(CDT)을 사용하였다. 반타원 균열을 가지는 평판과 원통형 용기에 대한 응력확대계수 비교를 통해 기법을 검증하였으며, 균열 해석에 유용함을 보였다.

• Steel and Composite Structures
• /
• 제34권5호
• /
• pp.681-698
• /
• 2020

The paper addresses contribution to the modeling and optimization of major machinability parameters (cutting force, surface roughness, and tool wear) in finish dry hard turning (FDHT) for machinability evaluation of hardened AISI grade die steel D₃ with PVD-TiN coated (Al₂O₃-TiCN) mixed ceramic tool insert. The turning trials are performed based on Taguchi's L₁₈ orthogonal array design of experiments for the development of regression model as well as adequate model prediction by considering tool approach angle, nose radius, cutting speed, feed rate, and depth of cut as major machining parameters. The models or correlations are developed by employing multiple regression analysis (MRA). In addition, statistical technique (response surface methodology) followed by computational approaches (genetic algorithm and particle swarm optimization) have been employed for multiple response optimization. Thereafter, the effectiveness of proposed three (RSM, GA, PSO) optimization techniques are evaluated by confirmation test and subsequently the best optimization results have been used for estimation of energy consumption which includes savings of carbon footprint towards green machining and for tool life estimation followed by cost analysis to justify the economic feasibility of PVD-TiN coated Al₂O₃+TiCN mixed ceramic tool in FDHT operation. Finally, estimation of energy savings, economic analysis, and sustainability assessment are performed by employing carbon footprint analysis, Gilbert approach, and Pugh matrix, respectively. Novelty aspects, the present work: (i) contributes to practical industrial application of finish hard turning for the shaft and die makers to select the optimum cutting conditions in a range of hardness of 45-60 HRC, (ii) demonstrates the replacement of expensive, time-consuming conventional cylindrical grinding process and proposes the alternative of costlier CBN tool by utilizing ceramic tool in hard turning processes considering technological, economical and ecological aspects, which are helpful and efficient from industrial point of view, (iii) provides environment friendliness, cleaner production for machining of hardened steels, (iv) helps to improve the desirable machinability characteristics, and (v) serves as a knowledge for the development of a common language for sustainable manufacturing in both research field and industrial practice.

• 대한의용생체공학회:의공학회지
• /
• 제19권4호
• /
• pp.341-350
• /
• 1998

대퇴 전염각의 정확한 측정은 뼈를 절개하여 각을 조절하는 시술(derotation osteotomy)에 있어서 매우 중요하다 대퇴 전염각을 정확히 측정하기 위해서는 대퇴골 장축과 목축, 관절구축의 정확한 선정이 필수적이다. 기존의 2차원 영상에 의한 대퇴 전염각의 측정 방법은 간단하지만 3차원 공간상에서 축들을 결정하기 모호한 단점을 가지고 있고, 3차원 영상을 이용하는 방법은 뼈를 밖에서 직접 측정하는 것과 같은 결과를 얻을 수 있어 2차원 방법보다는 정확한 측정이 가능하나 처리과정이 복잡하고 정량적이고 객관화된 결과를 얻는 것이 어려운 문제점을 가지고 있다. 본 연구에서는 대퇴골을 3차원으로 모델링하여 정량적이고 객관적인 대퇴 전염각의 측정법을 제시한다. 이것은 먼저 촬영된 슬라이스 영상들을 3차원상에서 재구성한 뒤, 대퇴골두와 목 모델로부터 대퇴골 목축을 정하고, 대퇴 관절구 모델로부터 대퇴 관절구축을 결정한다. 또한, 대퇴골 주축을 원통으로 모델링하여 장축을 결정한다. 대퇴 전염각은 대퇴관절구의 접평면에 대한 대퇴골축의 기울어진 정도로 정의되며, 이 정의를 이용하여 대퇴 전염각을 구한다. 결과에서 20명 CT영상으로부터 대퇴골 샘플을 측정하여 기존의 2차원 및 3차원 영상법의 결과와 비교하여 제시한 방법이 객관적이고 정확한 측정방법임을 검증한다.