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
제24권 제4호 (2022년 8월) 36건
1.
2022.08
구독 인증기관 무료, 개인회원 유료
9% nickel steel has remarkable mechanical properties in a cryogenic condition and is widely used in storage containers for LNG fueled ships. Demand for laser welding rather than conventional arc welding has grown to increase manufacturing efficiency. However there are various types of heat sources which are suggested by other researchers. With that, it is difficult to select a proper heat source shape for welding conditions. The author proposed a representative heat source model that can cover most of suggested heat source models through previous studies. Welding power was fixed at 4kW and the speed was changed to 1.0m/min, 1.5m/min, and 2.0m/min respectively. The shapes of the welding heat sources were derived, and the tendency of the main parameters was also deducted. It was observed that the width and depth of the weld bead decreased as the welding speed increased through welding experiment, parameters of welding heat source are changed linearly. Based on this study, it is expected that it will be possible to estimate the shape of the heat source under untested welding conditions.
4,000원
2.
2022.08
구독 인증기관 무료, 개인회원 유료
In the present study, it is conducted to understand the heating performance and compressor operation characteristics according to 7 indoor unit combinations and 3 setting temperatures of the inverter multi-heat pump under heating standard temperature conditions. Heating capacity, COP and compressor frequency are investigated using the multi-calorimeter. The indoor unit combinations are simultaneous operation(A+B+C), partial operation(A+C, A+B, B+C) and independent operation(A, B, C), and the setting temperature is 20, 21, and 30°C. Since the increase in the setting temperature increases the compress frequency, the heating capacity increases, but COP decreases due to the increase in power consumption. The frequency increases as the indoor unit combination capacity increases, and decreases as the setting temperature decreases in the steady state.
4,000원
3.
2022.08
구독 인증기관 무료, 개인회원 유료
생체용 마그네슘 합금은 전연성 부족과 열에 의한 팽창률 변화가 심하여 2mm 이하의 판재를 만드는 것이 매우 어려움 문제이다. 이를 해결하기 위해 압연 방식, 세이퍼 방식, 밀링 방식 등의 다양한 방법이 존재할 수 있다. 압연 방식을 적용하여 실험을 진행하였으나 Mg 합금은 전연성, 취성의 문제로 인해 파괴되는 현상이 발생하였다. 그리고 세이퍼 방식은 가공시 충격이 발생하는 단속절삭이기 때문에 표면에 자국이 남게 되고 시험편이 휘어지는 현상이 발생하는 문제가 발생하였다. 최종적으로 밀링 방식으로 전환하여 가공실험을 수행해 본 결과 매우 만족할 만한 결과값을 얻게 되었고, 이 결과는 절삭조건을 절삭회전수 1000rpm, 이송속도 127mm/rev, 절삭깊이 0.5mm로 엔드밀 사용하여 가공하였을 때 Ra = 0.44㎛의 표면거칠기값을 얻게 되었다. 본 논문에서는 생체 마그네슘 합금재료로 미소판재를 가공하였을 때 매우 좋은 표면을 유지하며 2mm 이하의 미소 두께를 지속적으로 가공이 가능하도록 하였으며, 다양한 절삭조건, 2날과 4날 엔드밀 날수 변화 등을 통해 최적의 가공조건을 알아보는 실험을 진행하였다.
3,000원
4.
2022.08
구독 인증기관 무료, 개인회원 유료
Most of automobile steering parts are manufactured through the multi-stage cold forging process using round-bar drawn materials. The same process is applied to the ball stud parts of the outer ball joint, and various research activities are being carried out to reduce the extreme manufacturing cost in order to survive in the limitless competition. In this paper, we present a quantitative prediction method for the limiting life of the die as a method for cost reduction in the multi-stage cold forging process. The load on the die was minimized by distributing the forming load based on process optimization through finite element analysis. In addition, based on the quantitative prediction algorithm of the limiting life of the die, the application of the split die and the optimization of the phosphate treatment of the material surface are presented as a conclusion as a method to improve the limiting life of the die.
4,000원
5.
2022.08
구독 인증기관 무료, 개인회원 유료
Diesel engine has the advantages of strong power, low fuel consumption and good durability, so it has been widely used in transportation, automobile, ship and other fields. However, the nitrogen oxides(NOx) and particulate matter(PM) emitted by diesel engines have become one of the main causes of air pollution. Especially during idling, the engine temperature is low, and there are more residual exhaust gases in the combustion chamber, resulting in the formation of more harmful emissions. In this study, performance of a single cylinder, four-stroke, direct injection (DI) diesel engine fueled with diesel–biodiesel mixtures has been experimentally investigated.
4,000원
6.
2022.08
구독 인증기관 무료, 개인회원 유료
This research was conducted for dewatered sludge cake of industrial wastewater treatment, i.e., as the object of inorganic sludge discharged especially in iron & steel manufacturing shop which used Air drying system to reduce water content. That drying system's single-type cyclone separator was confirmed to have significantly lower separation efficiency on the conditions 20μm and below of particular size through computational fluid dynamics(CFD) analysis. However, we found out the primarily advanced value of separation efficiency on dual-type directly connected. Regarding separation efficiency on size of 10μm, the efficiency of a single-type was presented at 51.91%. On the other side, the efficiency of the dual-type was 97.88%. This advanced effect of the dual cyclone separator was checked at a demo facility of air drying equipment designed by 340m3/min of airflow on site.
4,000원
7.
2022.08
구독 인증기관 무료, 개인회원 유료
Recently, the medical industry’s use of biomaterial has taken an important place. A biomaterial is a semi-permanent material that can be used instead of a specific part of the body when there is a disability. Among them, Nitinol alloy has used in the human body, the material surface quality is very important, and research on processing methods is important to improve the surface quality. Therefore, in this study, a study was conducted to obtain high-quality surface quality using the MR polishing process. As a result, high-quality surface roughness was obtained at a wheel rotation speed of 400rpm(Ra=3.5nm).
4,000원
8.
2022.08
구독 인증기관 무료, 개인회원 유료
Recently, 3D printing has been actively studied. A representative material in this 3D printing technology is plastic, and PLA, an eco-friendly material, is widely used. FDM is widely used as a way to output these PLA materials. However, this method lacks mechanical properties compared to injection-molded products as it is a method of stacking materials by melting. Therefore, in this study, using an FDM-type 3D printer, a tensile test was performed after printing a tensile specimen with PLA filament with the layer angle and layer density as control factors. After that, changes in tensile properties according to the layer angle and density were compared and evaluated. As a result, to improve the tensile strength, the layer density had to be considered, and to improve the elastic modulus, both the layer angle and the layer density had to be considered.
4,000원
9.
2022.08
구독 인증기관 무료, 개인회원 유료
In order to reduce environmental pollution, it is necessary to increase the recycling rate of waste. For this, the separation of recyclables is of utmost importance. The paper conducted a study to automatically discriminate containers by material for beverage containers among recyclables. We developed an algorithm that automatically recognizes containers by four materials: metal, glass, plastic, and paper by measuring the vibration signal generated when the beverage container collides with the bottom plate of the collection box. The amplitude distribution, time series information, and frequency information of the vibration signal were used to extract the characteristics indicating the characteristic difference of the vibration signal for each material, and a classifier was developed through machine learning using these characteristics.
4,000원
10.
2022.08
구독 인증기관 무료, 개인회원 유료
Hydrogen gas is usually used in many industrial facilities, for instance, such as semiconductor, vehicle and gas station. Because hydrogen embrittlement leads to the big damages in bolts, nut, especially, high pressure valves with common materials, therefore, special alloy including Monel material is recommended to reduce the hydrogen embrittlement. The purpose of this study is to investigate the characteristics of Monel within elastic limit through numerical analysis when Monel is drawn by drawing system. As the results, it showed that safety factor was decreased, but deformation and stress was increased, when the number of pass was increased. Furthermore, the method for designating work hardening in numerical simulation was needed to achieve the exact solution in this study.
4,000원
11.
2022.08
구독 인증기관 무료, 개인회원 유료
Study on Fishway Design and Flow Characteristics to Apply the Fishway in the Turning Type Flood Gate
In this study, numerical analysis is conducted to investigate the flow characteristics of a turning type flood gate fishway with various design factors. The shapes of the fishway are circular and rectangular type. Baffles are installed to reduce the velocity in the fishway, and the gap and rotational arrangement of the baffles are set as design factors. To reduce the maximum velocity, a cavity-shaped break region is installed to examine the flow characteristics according to the presence of the break region. As a result, in the condition where the shape of the fishway is rectangular, the outlet average flow velocity is larger than that in the circular condition. The highest flow velocity occurs when the baffle is rotated in 90-degree arrangement. As the baffle gap increases, the average velocity increases. The cavity-shaped break region creates a recirculation zone in the fishway, and as a result, shows a decrease in the maximum velocity of up to 5.8%.
4,000원
12.
2022.08
구독 인증기관 무료, 개인회원 유료
In this paper, based on the existing research, we define the parameters for the number of ignition devices to be applied to the pyrovalve, the operation and airtightness according to the temperature, the material of the nipple and the thickness of the fractured part, and ANSYS Ver. 19.2 was used to analyze the FEA model, and a comparative analysis was conducted through structure analysis according to the piston shape of the pyrovalve. In addition, an experimental study was conducted by manufacturing a prototype according to the design variables. As a result, high-strength pyrovalves can stably supply working fluids such as fuel and oxidizer for space launch vehicle propulsion engines, as well as precisely control flow path switching was confirmed.
4,000원
13.
2022.08
구독 인증기관 무료, 개인회원 유료
Dimethoxymethane, also known as methylal, is an oxygenated additive that contains approximately 42% oxygen content and is soluble in diesel fuel. Experiments were conducted by using the five kinds of blended fuels with different volumetric percentage of DMM in a diesel fuel. The test engine was used four stroke, single cylinder, DI diesel engine. Also, data was collected at 24 kinds of various engine speed-load conditions. The aim of this study was to examine the effects of the addition of oxygenated additive to diesel fuel on the emissions and the performance. Smoke emissions of all DMM blended fuels were reduced substantially in comparison with diesel fuel. In addition, this study showed that simultaneous reduction of NOx and smoke emissions could be achieved by oxygenated additive and EGR method that was applied to decrease smoke emissions increasing with NOx emissions reduction.
4,000원
14.
2022.08
구독 인증기관 무료, 개인회원 유료
Hydrogen embrittlement refers to a phenomenon in which the ductility and toughness of steel materials are lowered by hydrogen absorbed in metal materials, especially steel, and the tendency to fracture without plastic deformation increases. Fracture due to hydrogen absorption is also called delayed fracture, and it mainly occurs at grain boundaries, stress concentration areas, or areas subject to tensile stress. From a practical point of view, hydrogen embrittlement is frequently associated with corrosion, welding, pickling, electroplating, etc., and in materials, it is prominently displayed in stainless steel or high tensile steel. Regarding the embrittlement mechanism, there is no generally accepted orthodoxy. In this study, A hydrogen embrittlement mechanism is proposed. In addition, the method of suppressing hydrogen embrittlement will be considered.
4,000원
15.
2022.08
구독 인증기관 무료, 개인회원 유료
A heat exchanger refers to a pressure vessel that indirectly exchanges heat between low-temperature/ high-temperature fluids with a solid wall interposed therebetween, and a shell-and-tube cylindrical heat exchanger is generally applied. The shell-and-tube cylindrical heat exchanger is widely used in ships and there is a problem in that the welding area is narrow and welding defects occur a lot due to high-level welding. In particular, in the case of a ship heat exchanger, if a problem occurs in the welding part during operation, the possibility of a safety accident is high, and repair is not easy. In this study, to solve this problem, the GTAW(Gas Tungsten Arc Welding) method was applied to secure the optimum conditions for pipe welding of STS304 material with a thickness of 5.5mm and to conduct a test. Afterwards, in accordance with the ASME rules, welding performance was verified through cross-sectional observation of welds, mechanical property tests, (tensile strength, bending strength, cryogenic impact strength) and non-destructive testing(PT, RT).
4,000원
16.
2022.08
구독 인증기관 무료, 개인회원 유료
In this study, to develop and verify the Jeju-type groundwater thermal system design program, the energy consumption and system performance derived by input into the design program based on the load calculated on the demonstration site and the groundwater temperature were compared and analyzed with the actual measured values. The theoretical values of energy consumption and heating and cooling COP obtained through the Jeju-type groundwater thermal system design program were 11.24kW, 5.28 for heating, 13.31kW, 3.94 for cooling respectively. The measured values of energy consumption and COP of the Jeju-type groundwater thermal system were 3967.2kW and 4.5, respectively. The error between the theoretical value and the measured value obtained through the design program is 0% and 2.39%, respectively. The errors that occur in the predicted values and the actual values are due to variables that are ignored in the system assumptions. If users consider errors and use it when designing groundwater thermal systems, they can estimate the cost of required drilling works, heat exchangers, and heat pumps and analyze economic feasibility.
4,000원
17.
2022.08
구독 인증기관 무료, 개인회원 유료
In this paper, to improve the optical quality of aspherical plastic lenses for mobile use, the optimal molding conditions that can minimize the phase difference are derived using injection molding simulation, design of experiments, and machine learning. First, factors affecting the phase difference were derived using the design of the experiment method, and a data set was created using the derived factors, followed by the machine learning process. After predicting the model trained using the generated training data as test data and verifying it with the performance evaluation index, the model with the best predictive performance was the random forest model. Therefore, to derive the optimal molding conditions, random forests were used to predict 10,000 random pieces of data. As a result of applying the derived optimal molding conditions to the injection molding simulation, the phase difference of the lens could be reduced by 8.2%.
4,000원
18.
2022.08
구독 인증기관 무료, 개인회원 유료
In order to experimentally investigate the operation characteristics of the multi-heat pump with 3 indoor units, the dynamic characteristics of the cooling cycle is studied using the psychrometric multi-calorimeter. The compressor of the heat pump is the scroll inverter type, and since 3 indoor units operate cooling at the same time, it is operated at 100% full load. In particular, 3 types of indoor unit temperatures (20, 24, 26°C) are selected to understand the operation process of the multi-heat pump by the setting temperature. From this experiment, the compressor controls the EEV opening for each indoor unit while varying the frequency according to the initial start, transient, and steady operation. In addition, as the setting temperature increases in the steady range, the frequency of the compressor and the average opening degree of the EEV decrease.
4,000원
19.
2022.08
구독 인증기관 무료, 개인회원 유료
In this paper, cycle performance analysis of two-stage compression two-stage expansion refrigeration system using eco-friendly refrigerants is presented to offer the basic design data for the operating parameters of the system. Eco-friendly refrigerant R600a(Isobutane) for freon refrigerant R22 were used working fluids in this study. The coefficient of performance(COP) of R600a is about 5% greater than that of R22 two-stage compression refrigeration system in the range of evaporation temperature –30℃∼-60℃. The coefficient of performance of two-stage compression and two-stage expansion refrigeration system decreases with the increasing condensation temperature and superheating degree but increases with the increasing evaporation temperature, subcooling degree and mass flow rate ration of intercooler.
4,000원
20.
2022.08
구독 인증기관 무료, 개인회원 유료
In this paper, a simulation computerized crash analysis evaluation method through reverse engineering was applied to the Defender vehicle to systemize and simplify the certification of small-scale electric vehicles. The Defender vehicle was selected as a benchmarking vehicle that converts into an electric vehicle, and the layout of the frame and element analysis of individual parts were conducted through reverse engineering. To review the vehicle package layout, the fastening and assembly method for each part was analyzed referring to the Defender maintenance guide and parts list, and it was used for frame element technology analysis. In addition, collisions according to the main frame material and the shape of the crash box were analyzed, and various cases were analyzed through parameter study. As a result of the crash analysis, it was found that the mild steel main frame could not guarantee the safety of the vehicle in a fixed wall collision situation, and the ATOS material would increase the collision safety of the Defender relatively. Through the crash analysis according to the shape of the crash box, it was found that the strength of the crash box is too high compared to the main body, and this should be reflected in the design for small-volume production of multiple products.
4,000원
1
2
