Earticle

유니버설 조인트는 두 회전 축 사이에서 힘을 전달하는 구성 요소이며, 구동축과 피동축이 나란히 정렬되지 않아도 나란히 정 렬되지 않아도 동력전달이 가능하게 하며 각도 변화가 있는 전동축에서도 효율적으로 동력을 전달시키는 부품으로서 자동차의 동 력전달 장치에서 많이 적용되고 있다. 차량의 경량화를 위해 고강도 알루미늄의 사용이 증가하고 있다. 본 연구에서는 알루미늄 6061 재질을 사용하여 유니버셜 조인트 샤프트를 성형하기 위해 환봉 압출, U-Shape 성형, Spline 성형 등에 대한 단조 해석 연구하였다. Bar Extrusion 성형 시 23.3Ton, U-shape 성형 시 62.2Ton, Spline 성형 시 3.2Ton, 총 Cycle Time 226sec의 성형 조건을 산출하였으며, 이를 적용하여 알루미늄 유니버셜 조인트를 제작하였다. 비틀림 시험을 통해 토크값은 평균 425.8 (N・m), 비틀림 각은 평균 171.6∘ 의 실험값을 통해 기존 제품에 비해 단조 제품이 12.0∼14.4%의 비틀림 성능의 향상을 보였다.

When oil spill disaster on sea takes place, the most effective measure is to use oil fence with vertical wall. It has been big challenges that suitable oil fence in consideration of variety of variables such as wind speed, height of wave and current direction is chosen. And current characteristics below two of vertical wall was studied by PIV experiment with utilizing technic of visualized analysis like velocity distribution, contour of velocity and streamline pattern in flow characteristic between vertical wall of oil fence. In this study it is purposed to identify characteristics of inside water flow between two vertical walls depending on respective various water speeds to minimize outflow of floating article below bottom of vertical wall and observed that re-circulation flow and irregular vortex at certain places between two vertical walls occurred. Consequently, the study showed that failure of oil fence such as entrainment failure and submergence failure can be largely lessen by means of optimizing length between two vertical walls with water speeds.

The flow-surface interaction and resulting pockets is the case of a turbulence boundary layer. Conditionally sampled hot-wire measurements within the wall region show that a strong vortex forms within the pocket, bordering the upstream portion, which stay in the wall region. This vortex is the result of the rearrangement of existing sublayer vorticity and its amplification. The work in this area has been applied to the prediction and reduction of drag. The study is focused on determining change in the length scale of the pockets. An important relationship between pocket and modified wall has been found. By changing the upstream boundary condition at the wall, the length scale of pockets were decreased.

Pipe for water supply is one of the important parts that supply water to home, factory and so on. Water leakage in pipe for water supply due to deterioration, ground sinking and earthquake leads to enormous economical loss. Therefore, pipe for water supply should be designed to satisfy the requirement of, for instance, structural stability and fatigue durability. The purpose of this study was to investigate the fatigue durability of flexible joint for relaxing the impact due to earthquake and ground sinking. For this purpose, flexible joint was simulated using dynamic characteristics and fatigue life. As the results, the problem of fatigue durability may occur when flexible joint and pipe for water supply are treated as rigid body in simulation. Thus it means that the role of packing in flexible joint is very important and packing should be designed as optimal conditions that are considered fatigue durability as well as waterproof.

In this study, heat exchangers used in data center and building air-conditioners were tested according to the type of heat exchangers to select them for commercial use. The experiment was performed three samples, one micro channel heat exchanger, the same volume oval coil and the same performance oval coil. The experiment conducted under actual operation conditions in the data center and building. Micro-channel heat exchanger has lower air side pressure drop and higher capacity per volume than oval coil. It may be advantageous when the installation small space or the little design static pressure in the fan, such as in-row systems or CRAC installed in data center.

The purpose of this study was to establish the noise characteristics of noise sources and the corresponding noise reduction measures during each manufacturing process closest to the workers in the metalworking factory. To this end, the noise generated in the manufacturing process of metal products was measured and analyzed, and the frequency characteristics of noise sources and the causes of noise were identified. The noise map was used to predict the noise reduction effect. Moreover, it is expected that this will ultimately contribute to the reduction of human risks caused by the noise of the civil environment around metalworking factories.

In this study, a white smoke reduction simple prediction model of white smoke reduction heat exchange system was developed by using EES. In order to verify the reliability of the EES model, it was compared with the computational results. The developed EES predictive model was used to calculate the temperature and absolute humidity of the mixed SA and EA according to the change of cooling water capacity, flow rate ratio of SA/EA, and SA inlet temperature. The difference between final temperature and absolute humidity at the outlet of the mixer calculated by computational analysis and EES was within 1.4% and 3.6%. As the cooling water capacity and the inlet flow rate ratio increased, and as the inlet air temperature decreased, the temperature and absolute humidity of the mixer decreased. The most influential factor in the white smoke reduction effect among the design variables of the white smoke reduction heat exchange system was the flow rate ratio of SA/EA.

This paper presents a prototype of a three degree of freedom mannequin simulator for rehabilitation education. A three degree of freedom (shoulder 2, elbow 1) model which is similar to the human body is developed. In addition design of mathematical model with consideration about the resistance of muscles and ligaments is proposed. To apply ROM inspection method to the mannequin simulator, this paper introduces the PID controller of the mannequin simulator prototype with the ROM inspection method. Rehabilitation specialists verify the mannequin simulator with the ROM test method, and the validation experiments show that the simulator has “good” levels of similarity.

Water supply through the water supply system is an essential element for normal industrial and living, and the interruption of water supply due to leakage and breakage can cause major problems. Local leaks and breakdowns of pipelines that make up the water supply system are unavoidable problems caused by the aging of pipelines, which require water leak detection and prevention through monitoring the integrity of structures. In this study, smart bolts, which can be determined whether or not to be loosened, were proposed for bolts used for tightening water pipes, valves, etc. that make up the water supply system, and their applicability was verified through actual fabrication and experimentation.

This paper reports an uncertainty analysis of quantitative visualization methodology for slug bubble dynamics in downward-facing nucleate boiling condition. Measurement of dynamics of slug bubble, i.e. departing speed, frequency, and diameter, is very important to predict safety margin of thermal systems in moving vehicle. By employing high speed visualization and post-processing, we quantitatively measured the volume and location of slug bubble, so that vapor generation rate and departing speed data were derived from their time differentiation. As a visualization methodology, its reliability was evaluated via uncertainty analysis. For 95% confidence interval, uncertainty of vapor generation rate and departing speed were 3% and 2%, respectively, and which were one order lower than standard deviation of those data.

In this study, the shrinkage at the artificial skin tissue and temperature characteristics of rubber pole were analyzed by the experimental and numerical method. A artificial skin tissue was produced by using the rigid sponge pad. The impact of tissue was applied by three types of rubber pole. The shrinkage results along the depth of tissue were measured according to the repetition count of impact. When the shape of rubber pole was sphere type, the shrinkage was greatest. The temperature around the pole was highest in the sphere type while that inside pole was greatest in the twine deep sphere type. This is because the pole temperature of twine deep sphere type was transmitted more inside. As a result, the sphere type rubber pole was the most effective because it showed the largest shrinkage and the lowest temperature gradient during impact.

In this study, a high speed planing boat with 7.2 meters in length is developed as the beam larger about 10% by comparing with the general planing boat. The design speed of a boat is 30 knots (about 15.4 m/s) by using 150 hp outboard engine and the main material is FRP. The resistance performance related to the free running attitude as trim and sinkage is discussed and the wave patterns are observed to clear the relationship between the performance and wave characteristics by model test. The turning circle is estimated by Lewandowski´s equation. The results show that not only the wave pattern but also the free running attitude of the boat have the strong influence on a resistance performance. The boat needs smaller engine power and has more stable running attitude because of large sinkage and small variation of trim due to the large area for the lift force and light weight.

Recently air pollution is becoming a global environment issue. Especially, the smoke from engines and boiler systems, which burn fossil fuels directly, is an extremely serious issue. For this reason, IMO is tightening regulations for the control of NOx and SOx. Therefore, in this study, the NOx reduction effect of emulsified oil mixed with 10% of water was tested after applying the emulsified oil to an industrial boiler burner using Bunker-C oil. The study showed that the exhaust gas oxygen concentration of emulsified oil was nearly 1.3% high and this was identified by the effect of dissolved oxygen contained in water. Also, based on the standard oxygen concentration(4%), the average and maximum NOx reduction rates were 28.53% and 30.23% respectively, which means the reduction efficiency was very high.

In this study, the shape optimization of the injector according to fuel and tip was conducted through analytical techniques. As an analysis condition, a flow rate of 0.08 kg / s was applied to the inlet and the outlet was given a condition of 0 Bar. The working fluid for each fuel was applied. As a result of the analysis, it can be seen that the pressure and velocity of model with the modified tip become higher than that of the base model in diesel. Compared with the base model in the case of gasoline, the modified model of the tip was found to have more stable injection when the pressure inside the combustion chamber and the straightness of the fuel were observed. Finally, in case of LPG injector, the same modified tip as gasoline was found to be the more stable injection. On the basis of this study result, the shape parameters of the injector can be inferred.

As the solar power generation system expands, researches on the development and production technology of solar modules are being actively conducted. In addition, in the production of polysilicon for solar modules, a high-purity carbon electrode is essential, which greatly affects the performance and productivity of the solar module. This research is about the development of a carbon electrode used to manufacture high-purity polysilicon rod, which is essential for the manufacture of the photovoltaic modules. Fine graphite chuck is used as a carbon electrode. Generally, it is a consumable material that is used once and discarded. Therefore, this study aimed to develop an assembly-type high purity graphite chuck that can recycle some resources to dramatically improve the utilization of resources. In order to maintain the purity and performance of polysilicon, the composition and performance of the graphite chuck are important. The fine graphite chuck is manufactured through the high-purification process after precision machining, and the performance is confirmed through the component analysis of the specimen. At about 5,000 nm or more from the surface, the compositions of the sample appeared almost constant, and a high purity sample satisfying the target specification was obtained. In addition, it was confirmed that the cost reduction could be achieved by designing the graphite electrode as a separable type, and the results of this study can be applied to the design of the fine graphite chuck for the production of high purity polysilicon.

In this study, an algorithm for control of SPD(Suspended Particles Display) on Smart Skin was proposed. The office with SPD located in Jeonju, Jeollabuk-do was modeled and simulated using TRNSYS18. Through simulation, the energy and lighting consumption of building were analyzed The two kinds of control algorithm(SPD and dimming control method for cool energy and lighting energy saving(CASE 1) and improved control method(CASE 2)) were compared. For this research, Two models(with and without SPD and dimming control) were analyzed by comparing the cooling energy and the light energy consumption was reduced 15.1%, and the lightind energy consumption was reduced by 39.2% more than the model without SPD and dimming control. But, at the improved control method(CASE 2) the cooling energy consumption was reduced of more 2.5% and lighting energy consumptions was reduced of more 18.3% than CASE 1. When using SPD and dimming control, lighting energy consumptions showed more sensitive to solar radiation than cooling energy consumptions. As the improved control method(CASE 2) showed more advantageous saving tate than SPD and dimming control metrhod for cool energy and lighting energy saving(CASE 1), it was found that the improved control method (CASE 2) must be utilized in practice for SPD and dimming control.

In this experiment, the engine (i30 FD) was fabricated and installed in front of the intake manifold of the gasoline engine of the 2010 1,600cc MPI(Multi Point Injection) 4-cylinder 16-valve DOHC(Double Over Head Camshaft) electronic control fuel injection system, and the plenum chamber was 150cc, 300cc, 4. The engine rotation speed was increased from 1000rpm to 3000rpm by 500rpm, and the pressure change and engine volume efficiency change of the air intake manifold runner were analyzed. In this study, the volume of air flowing into the cylinder was maximized through the stabilization of pressure vibration in the intake manifold runner part due to the engine operation condition and the volume change of the intake manifold plenum chamber, and the uniform distribution rate of the intake air was confirmed by minimizing the interference between the cylinders. It has in the purpose to analyze the flow characteristic at the intake manifold inside. It can apply to obtain the optimal design factor.

In this study, in order to solve the quality problem (Safety accident) that the chain breaks out of the wheel gear due to the problem of the spare tire carrier device, the wheel gear is rotated in such a way that the upper part of the chain is caught on one side of the triangular wheel gear. When falling, the tire falls due to the chain falling off and the chain is caught by the wheel gear so that it cannot bear the tire load and slip occurs. Also, in order to solve the quality problem that the chain is caught (Due to malfunction), the “ㄷ” shaped chain the guide should play the role of guiding the movement of the chain by holding the chain in the direction. The technical development goal is to solve the problem of the chain dropping and the chain hanging from the wheel gear of this product.

The purpose of this study was to establish the noise generation actual condition of large machine in plant. most of the plant's large-scale machines are designed and manufactured overseas, so it is difficult to access basic information. The regulatory standards, management plans and measurement methods for these machines are insufficient. It is necessary to obtain information about the noise storage devices installed for warranty and the noise reduction device when designing the equipment. Investigation of the occurrence of large-scale machine noise at domestic plant sites was conducted. The sound insulation design of the industrial safety and health care law benchmark and the large-scale machine compound noise design of the equipment are carried out.

A two-phase flow in mini-channels is consist with various flow regimes (such as bubble slug, annular, churn flow) according to gas and liquid phase flow rates. A previous researches revealed that in a case of slug flow in hydrophobic mini-channels, gas and liquid phase are perfectly separated by interfaces and triple contact line. In this study, the single dry slug flow experiments in circular mini-channel (D = 1.018 mm) are conducted to observe interfacial break-up phenomena in high capillary number range (Ca < 0.02). The slug is consist with D.I. water or D.I. water-ethanol binary mixtures (5% and 10%, mole fraction). On the base of previous researches, we calculate the pressure drop at moving triple contact line. In an addition, a single dry slug flow is visualized by using high-speed camera. Through the experiment, three regimes of pressure drop are observed; steady, loss, separation. As a result, criteria between steady and loss regimes is closely related to capillary number, and criteria between loss and separation regimes is related to surface tension.

In this study, the uniformity of the horizontal velocity and the temperature of each zone were investigated by computerized analysis method to divide the drying room into three multi - rooms to ensure the uniformity of flow inside the forced convection hot air dryer. The internal structure of the drying room of the dryer was modeled using Solidworks. In order to control the flow of hot air circulating in the drying chamber, the possibility of controlling the horizontal flow inside the drying room was verified by using a perforated plate, a guide vane, and a vertical plate. From the results of the flow visualization in the drying room, it was understood that the internal flows of the dryer models 1, 2 and 3 change from ununiform flow to uniform flow. From the analysis of velocity and temperature fluctuation, the results of the analysis of the dryer model 3 satisfied the design conditions.

This paper proposes a method to reduce the pose error and to solve the dead reckoning issue which occurs when the mobile robot with continuous-tracks travels in the unstructured environments. When the continuous-track type mobile platform travels on terrain such as sand, gravel, stairs and etc., slippage occurs and thus the driving state of the mobile robot cannot be recognized normally. To compensate for this pose error, the proposed method utilizes optical flow estimation detected by camera. This method is tested through experiment. Finally, This method reduces the pose error detected on inertia measurement unit within some limit, while the pose error of without compensation increases without limit during robot move.

In this study, the energy use of buildings was compared and analyzed by using weather data predicted with machine running techniques. Python was used as a predictive program to predict weather data and TRNSYS was used to simulate the energy usage of buildings. For weather forecasting, weather data from 1 August to 7 August were studied to forecast ambient air temperature and solar radiation. The lowest error came in seven days, with the outside air temperature standing at 1.8 percent and the solar radiation at 2.4 percent. The energy use of the building was simulated by using weather data predicted through the 7 days learning data with the lowest error. As a result , the error rate of cooling energy use was 1.92%, the sum of cooling energy and lighting energy use was 1.79%, and the building control by using predicted weather data didn’t show a big difference with just control.

Due to rapid industrialization and urbanization, maintenance of high voltage transmission lines in narrow alleys, complex roads, or old factory areas is required. Since the existing aerial lift vehicle is made of steel, there is a risk of electric shock. Therefore, there is a need for the development of an insulated aerial lift vehicle that can prevent electric shock accidents during electrical work. In particular, the development of an insulated aerial lift vehicle is required in a recent work environment where live line work is inevitable. The development of composite insulation boom for the vertical swing type aerial lift vehicle is studied. The insulated boom was developed by applying glass fiber-epoxy composite and filament winding process. The developed insulated boom was verified by measuring dielectric breakdown strength, surface resistance and volume resistance according to ASTM D149 and ASTM D257.

Cassettes are a key component for power transmission and smooth shifting, and their construction consists of sprockets and spiders. The sprocket receives the force generated by pressing the pedal through the chain and rotates the rear wheel. It is a circular part. As the shifting system for efficient driving of bicycles has been developed, chains and sprockets require more complicated shapes than the conventional ones, and researches are being conducted to increase the production efficiency of sprockets. Cr-Mo steel is mainly used as the material for sprockets, but the trend of converting high-performance cassette material to titanium, which is a material with high specific strength, is gradually increasing. In this study, we also studied the molding technology of titanium material for the 5th and 6th stage shape design, the finite element analysis and the mass production using the press mold.

As carbon fibers have the high performance, such as high strength, light weight, and high corrosion resistance, they are gradually expanding and growing at various industries. In particular, this study was conducted to determine whether the market could be applied to street lanterns among the construction sectors expected to grow in scale. In this study, the material characteristics of street lanterns using carbon fiber composites were studied in order to determine whether carbon fiber composites could be applied as a substitute for stainless steel and cast iron street lanterns. The physical relationship was experimentally evaluated to obtain a suitable material through the comparison of physical properties of fiber composite materials.

The technology competitions of automobile manufacturers are getting hot. The characteristics of the environment friendly automobile are not only lowering the emission of harmful exhaust gas through the change of the power source, but also paying great attention to improvement of the power efficiency. As the market for pure electric vehicles continues to grow, we have analyzed the global technology competitiveness by DCT (Dual Clutch Transmission) patents. Clustering can be classified into five types ; 1) a cluster associated with a dual clutch transmission system, 2) a cluster of a torque transmission device and a reverse speed ratio, 3) a cluster of co-planar sets and dual clutch assemblies related to transmitting devices, 4) Device clusters, and 5) a cluster of synchronizers and clusters to prevent simultaneous operation of dual clutch transmissions. In recent years, demand for pure electric vehicles has been rapidly increasing, and patent applications related to DCT have been steadily increasing for energy efficiency of motor power sources.

In this study, the injection pressure of 31 MPa and clamping force of 1,000 kN toggle electric injection molding machine were used to measure the load transmitted to the frame during injection molding and to use it as the design basis data. In general, the toggle structure is composed of a movable plate, tie bars, crossheads, toggle links, toggle pins, base plates, etc and The material is spherical graphite cast iron(FCD 400). In this study, it was found that there was a 1.3% safety factor by calculating the clamping force in the structure of the five-point toggle link system. In addition, Expected static bottom load, Expected dynamic additional load, Maximum expected additional load, and Maximum weight load were measured using tensile measurements and presented as important basic design data of the assembly.

Deicing agent refers to the substance that melts snow by exothermic or endothermic chemical reaction after spraying on snow. It also has the function of reducing the freezing point to prevent freezing. However, the long-term use of deicing agent can cause some negative problems, such as pot hole, concrete corrosion, vehicle and steel bridge parts corrosion. At present, wet salt spray deicing is a cost-effective deicing method that is being widely used. Typical deicing agents are calcium chloride and sodium chloride. Deicing equipment is placed to similar or higher corrosive environment than coastal or marine environment due to direct contact to chloride in deicing operation. Therefore, the anti-corrosion control is very important for the maintenance of deicing equipment. In this study, corrosion resistance, blistering and repairability of the deicing equipment were tested by using test standard (salt water production and spraying- KS D 9502 , evaluating degree of rusting- ASTM D 610, evaluating degree of blistering- ASTM D 714, pull-off strangth of coatings- ASTM D 4541). And an economical coating system with long-term antirust performance was constructed. The results show that the performance of the coating system has been improved than with the original coating.

FDM 3D Printer is used in maker space for mass production by the maker. Makers desire to manufacture products in a variety of colors using ABS Filaments. The purpose of this study is to identify the relation between the color of resin and each position on the bed. So, when printed using the 3D Printer, we found out the difference in the colors that it appears depending on the position of the bed. To see the difference in color, basic, blue, yellow, white, and black were selected and the bed plate was divided into three sections. Specimens were measured to obtain delta E values between each sections by the chromatic differential system. Obtained delta values were analyzed by the NBS system. As a result, the delta E value of black was found to correspond to “Appreciable”. In most cases, delta E values between the middle and the outer or the inner and the outer was greater than values between the middle and the inner. Using Infrared Thermal Camera, We found that the color difference relates 3D printing positions and temperatures. As a result, the 3D printing bed positions should be considered when 3D printing mass production.