간행물
한국기계기술학회지 KCI 등재 Journal of the Korean Society of Mechanical Technology 韓國機械技術學會誌
- 발행기관 한국기계기술학회
- 자료유형 학술지
- 간기 격월간
- ISSN 1229-604X (Print)2092-0385 (Online)
- 수록기간 1999 ~ 2024
- 주제분류 공학 > 기계공학 공학 분류의 다른 간행물
- 십진분류KDC 550DDC 620
권호리스트/논문검색
제22권 제2호 (2020년 4월) 29건
1.
2020.04
구독 인증기관 무료, 개인회원 유료
In this study, numerical analysis was carried out to develop low-noise axial fans, which are often used for ventilation in houses. A commercial program and the turbulence models are used for the analysis of internal fan. Proudman acoustic power model and the Curle surface acoustic power model were used for analysis. As a result, the distribution of flow velocity and pressure around the blade and guide of the fan was high, and low in the center of the fan. Noise from the inner wall of the fan case and the blade surface was the highest at the body and vane connections of the blade, and low at the center of the vane and the center of the body.
4,000원
2.
2020.04
구독 인증기관 무료, 개인회원 유료
The potential for biodiesel to replace diesel has been explored as an alternative fuel for naturally aspirated indirect injection diesel engines. Overall biodiesel smoke emissions were significantly reduced compared to diesel fuel, which was approximately 36% lower at 2000 rpm, peak load conditions. And torque, power and brake energy consumption did not show much difference. However, compared to diesel fuel, NOx emissions from biodiesel have increased. To combat this problem, an EGR(exhaust gas recirculation) method has been applied to reduce NOx emissions. It was confirmed that simultaneous reduction of NOx and smoke was confirmed by cooling EGR method(10~15%) and biodiesel(20 vol%).
4,000원
3.
2020.04
구독 인증기관 무료, 개인회원 유료
The calculation of the optimal trajectory of the stepped top-down robot was made using a genetic algorithm and a computational torque controller. First, the total energy efficiency was minimized using the Red-Cold Generic Algorithm (RCGA) consisting of reproductive, cross, and mutation. The reproducibility condition related to the position assembly of the start and end of the stride and the joints, angles, and angular velocities are linear constraints. Next, the unequal constraint accompanies the condition for preventing the collision of the swing leg at the corner with the outer surface of the stairs, the condition of the knee joint for preventing kinematic peculiarity, and the condition of no moment in safety in the traveling direction. Finally, the angular trajectory of each joint is defined by fourth-order polynomial whose coefficient is to approximate chromosomes. This is to approximate walking. In this study, the energy efficiency of the optimal trajectory was analyzed by computer simulation through a biped robot with seven degrees of freedom composed of seven links.
4,000원
4.
2020.04
구독 인증기관 무료, 개인회원 유료
Considering the features of body repair for automotive body where same damage and repair conditions does not exist in car accident, it is essential to acquire know-how and continuously approach new materials and new technologies on the site of maintenance where the theoretical instruction of textbook cannot react accurately minute by minute. Especially, in case of car repair from unexpected accidents such as body repair or dent repair, it is difficult to satisfy vehicle owners despite their request. Accordingly, this study researched the better maintenance technology to restore to its original state with more improved technology as vehicle owners wish. This study made time to repair reduced by 98% and the cost reduced by 79.6% through the accurate diagnostic technique before repair and maintenance technologies of body crash analysis applying property of high-speed tensile. It also obtains intangible effects including prevention of environmental pollution and maximization of vehicle owners satisfaction.
4,000원
5.
2020.04
구독 인증기관 무료, 개인회원 유료
This paper introduces the new concept of a gripper mechanism mounted on the home cleaning robot. This new mechanism composed of two grippers and an auxiliary dustpan can tidy and load up objects. We additionally analyze the required motor torque and dynamic motion of this robot using dynamic simulation of Recurdyn. This new tidying gripper mechanism is expected to be used in various home cleaning applications.
4,000원
6.
2020.04
구독 인증기관 무료, 개인회원 유료
The digital image correlation method is useful and widely used to measure the deformation of thin film materials for mechanical testing and provides full-field deformation of the specimen. The accuracy and precision of the digital image correlation method depends on the quality of the image obtained during the test. The noise included in the digital image causes errors in the calculated displacement results. Strain is calculated by differentiating the displacement, so the effect of noise is amplified in the calculated result of strain. Therefore, noise is one of the most important factors in measuring displacement using images. In order to evaluate the effect of noise, one hundred images were taken continuously in a stationary state and the distribution of the local strain was calculated using digital image correlation. If the size of the subset is greater than 15×15pixel, the calculated results for strain show that the effect of noise is within the maximum error range of 1% and the standard deviation is 0.11% or less.
4,000원
7.
2020.04
구독 인증기관 무료, 개인회원 유료
This paper reports the pH effect of reduced graphene oxide (RGO) colloids on formation of three dimensional (3D) graphene network in nucleate boiling condition, so called boiling method. When nucleated bubbles grow on the hot surface, thin liquid film beneath the bubble is supposed to be dried, in which RGO flakes become close to each other and form a structure. Accordingly, what happened when they are in high particle density would be a key issue for the formation of 3D graphene network. Here, we changed pH and oxidation level of RGO colloids so that their effect was observed on extent of 3D graphene network after boiling method. As pH was lower, i.e. being acid, the RGO colloids become unstable, resulting in 3D structure rather than 2D structure. Similarly, As oxidation level was lower, i.e. being more reduced, it showed a tendency to form 3D structure.
4,000원
8.
2020.04
구독 인증기관 무료, 개인회원 유료
This study aims at investigating the fracture characteristic according to the shape of the double cantilever beam specimen for mode II with ultra-high strength steel and Mg alloy steel. As the analysis, all three models had the left-hand holes that were constrained by the cylindrical support and the right-hand holes were enforced by the constraint condition of 6mm/min. This study result showed that the shorter the load block of the double envelope test specimen, the higher the safety. The results of this study are thought to be useful for examining the fracture characteristics of specimen for mode II with ultra high strength steel and Mg alloy steel.
4,000원
9.
2020.04
구독 인증기관 무료, 개인회원 유료
In this study, the spray characteristics of blending fuel with diesel fuel and high viscosity biodiesel fuel was investigated. The research was performed for the effect on biodiesel fuel blending ratio and injection pressure for the spray behavior. The experimental process of spray injection was analyzed with LDPAlaser diffraction particle analyzer). In addition, spray atomization characteristics were researched with SMD(Sauter mean diameter) and droplet distribution on various injection pressure conditions. Fuel containing high viscosity biodiesel fuel has some different spray behaviors on account of the viscosity and surface tension. Though this experimental result, we found that the increase of injection pressure enables SMD to get smaller, but the increase of blending ratio makes SMD larger.
4,000원
10.
2020.04
구독 인증기관 무료, 개인회원 유료
This study reinterpreted Tesla’s gravity theory by Dirac's vacuum. Most of the mass in the proton is in the form of energy from color charges field. Dirac's vacuum, in which virtual particle-antiparticle pairs are constantly producing and annihilating repeatedly, is polarized by the electric and color charges contained in the masses. Polarization of the virtual particles leads to rigidification of the vacuum, which leads to paralysis of the vacuum’s function of gravity transmission. This paralysis of the vacuum’s function of gravity transmission between the two masses does not allow the gravitational field lines to pass each other, and finally, causes universal gravitation. For the aspherical anisotropic gravitational field, it is found that the symmetry of universal gravity is not maintained, unlike the result obtained by the principle of superposition. This study interprets universal gravitation mechanism by using vacuum polarization.
4,000원
11.
2020.04
구독 인증기관 무료, 개인회원 유료
CFRP materials are one of the excellent lightweight materials of the next generation. Also, the CFRP materials are attracting materials form the global automotive industry. However, CFRP material is made at a high cost of carbon fiber as raw material, so research of production cost reduction into the development of molding equipment and molding process technology related to mass production for the automotive industry is actively administered. Generally, CFRP is known as a high corrosion-resistant material in which no corrosion occurs. However, the investigation of the relationship with corrosion behavior on the roughness of CFRP's conditions according to is rarely studied. In this paper, the surface roughness has conducted three surface roughness conditions given arbitrarily, and the electrochemical evaluation has performed under the electrolysis conditions of 5 wt.% NaCl, which is the salt-water test condition of vehicle parts in automotive industries. Moreover, the samples were analyzed with changes of microstructures by FE-SEM and chemical composition's variation by EDS before and after electrochemical evaluation.
4,000원
12.
2020.04
구독 인증기관 무료, 개인회원 유료
This study is carried out to analyze the velocity distribution for each location and the uniformity index according to straight distance on exit side by changing the design factors of branch pipe connected to 180° circular mixing-tee using RSM(Reynolds Stress Model) turbulence model. As the results of the flow characteristics according to hydraulic diameter, the velocity profiles in the 90° sectional area are generally similar. In the 180° section, the maximum velocity point shows Y/D=0.7~0.8 after rapid increase of the flow velocity. In the result according to the distance away from inlet, the maximum velocity point in the 90° sectional area is located in outer side of the curved pipe as the distance away from inlet increases. In the 180° sectional area, the maximum velocity point is showed in Y/D=0.7~0.8 after the rapid increase of the flow velocity regardless of the variation of branched distance. In case of inclined angle, the maximum velocity point in the 90° sectional area is located in outer side of the curved pipe as the inclined angle increases. In the 180° sectional area, the maximum velocity point is observed in Y/D=0.8 regardless of the inclined angle. In addition, the uniformity index of flow velocity shows that it is stabilizing after approximately L/D=40 away from the end of the curved pipe regardless of the flow factors in the branch pipe.
4,000원
13.
2020.04
구독 인증기관 무료, 개인회원 유료
In this research, a capacitance pressure sensor with graphene membrane and titanium substrate have been developed and studied as a potential robust substrate and a sensitive membrane material for micromachined devices. Mechanical lamination process combined with micromachining processes have been selected for the fabrication of the pressure sensor. Prior to the fabrication, capacitive pressure sensors based on a graphene diaphragm and titanium substrate have been designed. The fabricated pressure sensor uses a titanium substrate, a graphene film laminated with a floating movable plate, and a fixed surface micromachined back electrode of electroplated nickel. Finite element method is adopted to investigate the residual stresses formed in the process.Also, the out-of-plane strain is calculated under the pressure of the diaphragm. The sensitivity of devices manufactured using these techniques is 7.5 to 4 kPa-1, and the net capacitance change in the range of 0 to 180 kPa is 013 pF.
4,000원
14.
2020.04
구독 인증기관 무료, 개인회원 유료
In this study, the uncertainty in the ballistic test was calculated. Characteristic factor plots were used to identify the sources of uncertainty. The results are as follows. First, the uncertainty about the projectile was calculated to be 0.008m/s. Second, the uncertainty for depth measurement was calculated to be 0.03mm. The biggest factor influencing the uncertainty was the human error by the measurer. Therefore, in order to reduce the uncertainty, it is necessary to minimize human intervention by introducing automatic measuring equipment.
4,000원
15.
2020.04
구독 인증기관 무료, 개인회원 유료
Vortex tube is a simple structure and environmentally friendly method of temperature separation. In this paper, the applicability of the vehicle air conditioning system using the Vortex tube was reviewed. Experimental conditions, the pressure was set at 0.5~5.0kgf/cm2, and the cold air flow ratio (yc) was set at 0.1~0.9. Experiment result, the high temperature section represents the highest temperature value at yc=0.8. The cold zone represents the lowest temperature value at yc=0.5. In case of indirect heat exchanger experiment result, the maximum temperature difference was 11°C in the cold zone and 15°C in the hot zone. In case of direct heat exchange, the low temperature area was 11°C and the high temperature area was 11°C. According to the experiment result, although indirect heat exchange method performs better than direct heat exchange method, the time to reach normal temperature is four times slower than direct heat exchange method. Therefore, in order to apply to a vehicle air conditioning system, it is judged that it is effective to use a direct heat exchange method having a fast reaction speed and a low flow rate resistance.
4,000원
16.
2020.04
구독 인증기관 무료, 개인회원 유료
PartI of this paper identified the location and size of the noise sources from the axial flow fans, and partII based on that, identified the magnitude of sound pressure from the case and the blade according to frequency in the range of 2200 Hz to 5000 Hz. The equation of Lighthill was used for calculation. Generally, when measuring noise, the analytical area was extended more than 1m from the outlet of the fan. To eliminate the effects of backflow coming from the rear of the fan, the analytical area was extended a little longer than 1m. From the results of the analysis, high noise occurs in the low frequency area, and the lower noise becomes in the high frequency area. The maximum sound pressure generated in the range of 2000Hz~5000Hz is 65dB at a distance of 1m and 82dB at the outlet of the fan. Noise of the fan mainly occurred around the blade and guide, and the noise decreased as the frequency increased between 2200Hz and 3400Hz, but the noise increased as the frequency increased between 3800Hz and 5000Hz.
4,000원
17.
2020.04
구독 인증기관 무료, 개인회원 유료
Recently, home workout has attracted attention as it can be done easily and conveniently at home. Accordingly, many types of home workout equipment are produced but, these kinds of exercise equipment using dumbbells or weights are too heavy to use for at-home-workout and they are too bulky in size. This paper studies a form of exercise done at home which is using a motor instead of dumbbells and weights that are originally used in the exercise equipment. DAFUL, a multi-body dynamics analysis program, is used to verify the dynamic performance of the proposed equipment. Therefore, motor-based exercise equipment is expected to be smaller than existing exercise equipment and more suitable for use at home.
4,000원
18.
2020.04
구독 인증기관 무료, 개인회원 유료
An underwater cable guide device which is using the caterpillar movement to move smoothly along the slippery and curved surface of the cast iron pipe was developed. We performed structural analysis with maximum stress and structural safety for the designed guide device. As a result of the structural analysis, the maximum stress occurred between the connecting link and the pin, and it was confirmed that it was structurally safe by satisfying the safety factor of 2.5 or more. In addition, we performed modal analysis to find out the possibility of resonance between the guide device and motor for driving the Caterpillar. The natural frequency of guide device was calculated to be higher than the frequency of motor ,so no resonance was found. We tested performance of the developed guide device, the target performance was satisfied in the watertight test, salt spray test, vibration test, and durability test.
4,000원
19.
2020.04
구독 인증기관 무료, 개인회원 유료
In this study, the laminar burning velocity of low calorific gas fuels are verified through the comparison and examination of experimental and predicted results. The bunsen burner which has contraction nozzle is used to measure the laminar burning velocity with the cone angle method. In addition, PREMIXED code combined with two mechanism, i.e., the GRI 3.0, and USC II reaction mechanisms is used to predict the laminar burning velocity. As heating value decrease, the laminar burning velocity correspondingly decreases due to inert gases in the fuels. Through the comparison and analysis of the experimental results and the predicted results, it is confirmed that LCF 9000 and LCF 8000 with the GRI 3.0 reaction mechanism and LCF 7000 and 6000 with the USC II reaction mechanism have a similar distribution of laminar burning velocity between the experimental result and the predicted result. This similarity is due to a large amount of propane, which is not suitable for the GRI 3.0 reaction mechanism in LCF 7000 and 6000.
4,000원
20.
2020.04
구독 인증기관 무료, 개인회원 유료
The verification and the design improvement of weight-training machines were performed. This research was carried out with computer simulation using the musculoskeletal model of the human body. The main topic of this research is the improvement of an arm-curl machine. Also the improved exercise effects were observed in this paper. The existing exercise which moves the scapula on the axis of the elbow with raised forearm is effective for only Biceps. We suggested the new concept arm-curl machine that also raises the scapula after raising the forearm to be effective for Triceps and adjacent muscles. The exercise effect to the Biceps and Triceps was verified in the partⅠ, that to the non-adjacent muscle such as Lattismus Dorsi was verified in the partⅡ of this study. The analysis with computer simulation using the musculoskeletal model could be helpful to develop improved healthcare machines with reduced price and time.
4,000원
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