한국기계기술학회지 [Journal of the Korean Society of Mechanical Technology]

간행물 정보
  • 자료유형
  • 발행기관
    한국기계기술학회 [Korean Society of Mechanical Technology]
  • ISSN
  • 간기
  • 수록기간
  • 등재여부
    KCI 등재
  • 주제분류
    공학 > 기계공학
  • 십진분류
    KDC 550 DDC 621
제19권 제2호 (22건)



이종재료 하향 경사계면의 길이 효과


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.149-155

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This study discusses the length effect of the downward inclined surface to apply the inclined interface surface design of the composite material under shear loading. The fracture parameter is analyzed by finite element method of the ANSYS. If the negative shear displacement is applied, energy release rate is reduced further to about the increasing inclined length, and the positive shear displacement applied, it had increased rather. If the negative shear displacement is applied, the reduction in the energy release rate in crack tip is found to be affected by the reduction in shear stress. If the positive shear displacement is applied, the increasing in the energy release rate in the crack tip is found to be affected by the increase in shear stress.



자동압착기의 형상변화에 따른 구조와 피로해석 연구

차재민, 변선준, 왕쩐후안, 권영철

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.156-161

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In the present study, the structural and fatigue analysis on the shape change of an automatic press are investigated for prediction of operation safety and reliability of the automatic press along the thickness(t) and length(L) of head, and corner shapes(case 1, 2, 3). The equivalent stress and deformation characteristics of the automatic press were studied by computerized analysis method for the bushing production of the seat frame. An external stress of 14.0 MPa was applied to predict the operation stability and the fatigue limit of the structure. As the thickness of the header increased and the length of the header decreased, the load stability applied by the piston improved and the maximum stress and deformation were reduced. In addition, due to the change in shape of the corners, the load applied at the cross-sectional area of the corners decreases, and then the maximum stress and deformation appearing in the header are reduced. That is, the change of corner shapes affects the equivalent stress and deformation. That is the change of corner shapes affects the equivalent stress and deformation. From the fatigue and vibration analysis, fatigue failure does not occur even when the number of alternating operation of the automatic press increases, and the natural frequency is predicted for dynamic characteristics.



가스 스프링 Elevation 동작 마찰력 보상 연구 - 피스톤 로드의 부피 보상 장치 및최적화된 피스톤 구조 개발


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.162-170

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In this study, factors analysis is performed for reducing friction in elevation motion of a large television stand over 50 inch. The first study is for specification decision and volume compensation experiment as an apparatus for compensating of the volume of the cylinder is compressed as the volume of piston rod. The second study is for optimized piston structure development by comparison pipe orifice and labyrinth orifice. Consequently, the result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod ∅8 x ∅4 and riveting system. and the labyrinth orifice is not founded that of the Ø0.4~0.6 orifice both tests on 300 mm intervals.



PEMFC 사다리꼴 단면 가스채널에서의 물 액적의 거동에 공기 및 물 유입 속도가 미치는 영향

고영진, 김우태

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.171-177

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In a PEMFC gas channel with a trapezoidal cross-section, the effect of air and water inlet velocities on water removal characteristics is numerically studied via the volume of fluid(VOF) method. When the channel wall contact angle is 60 degrees, the air inlet velocities higher than 2.5 m/s are advantageous to obtain lower GDL surface water coverage ratio(WCR). The WCR increases as the wall contact angle increases to 90 or 120 degrees due to the relatively lower surface tension force. In overall, WCR decreases as the air inlet velocity increases and WCR increases as the water inlet velocity increases.



고압튜브 내에서 분출되는 공기의 압축성유동 특성에 관한 수치해석 연구

정종길, 조정권, 윤준규, 임종한

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.178-185

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In this study, FLUENT v.16.1 was used to investigate the compressible flow generated by the supersonic jet spewed from a high pressure tube. As the boundary condition for CFD (Computational Fluid Dynamics) analysis, the inlet temperature of air was constantly 300 K and the variation of JPR (Jet Pressure Ratio) were 5, 50, 100, 150 and the variation of tube diameter were 10, 20, 30 cm. As a result, it was confirmed that the effective range was increased as the JPR was higher, but it was confirmed that the effective range was lower than the JPR rise, and that the effective range was increased as the diameter was larger. Therefore, it is found that the tube diameter is more sensitive than the JPR among the influence factors of jet, and if the result of this study were reflected in the design of high pressure system, it will contribute to the design of the system for preventing the second accident.



Lattice Boltzmann Method과 Smoothed Profile Method을 이용한 동심원의 자연대류 시뮬레이션

수레쉬 알라파티

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.186-193

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In this work, the natural convection in an annulus between two concentric cylinders is studied numerically. The fluid flow between the cylinders is solved by the lattice Boltzmann method (LBM) while a separate finite difference method (FDM) is used to solve the heat transfer. No-slip and constant boundary conditions at curved boundaries of the cylinders are treated with a smoothed profile method (SPM). At first, the velocity and temperature profiles obtained from the present LBM-SPM and FDM-SPM are validated with the corresponding theoretical results. Later, natural convection simulations inside the annulus are performed using coupled scheme of LBM-FDM-SPM by varying Ra in the range Ra=1000, Ra=10000, Ra=50000, and Ra=100000. From the temperature and fluid flow patterns obtained at different Ra, it is found that the heat transfer is mainly dominated by conduction process when Ra is low and by convection process when Ra is high.



Intake System이 Four-valve SI 기관 연소실 내 유동장에 미치는 영향


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.194-200

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In-cylinder flows in a motored 3.5L four-valve SI engine are investigated quantitatively using three-dimensional LDV system to determine how intake system affects the flow field. For this study, the same engine head, cylinder, and piston are used. The purpose of this work is to develop quantitative methods which correlate in-cylinder flows to engine performance. The LDV results reveal that collision regions and zones around vortices can be traced as the origins of turbulent kinetic energy. High levels of turbulent kinetic energy are found in regions of high shear flow, attributed to the collisions of intake flows. These specific results support the more general conclusion that the inlet conditions play the dominant role in the generation of the turbulence fields during the intake stroke.



250km/h급 고속용 강체전차선용 이행장치의 동적해석 모델 개발

원용희, 김봉석, 배상준, 장광동, 이기원

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.201-208

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In development of high speed Rigid conductor line(R-bar) over 250km/h, it is important to develop the method to anticipate the mechanical stability of the R-bar and of the transition structure which connects the flexible Overhead Contact Line. To do this, firstly, the FE(Finite Element) model for a transition structure was established and the initial deformed configurations due to gravitational force is obtained by a static analysis and the pantograph was modeled by a simplified mass-spring-damper system and the contact behavior between conductor and pantograph was defined by the penality method. Secondly, FE analysis results were reviewed with the test results of contact force between conductor and pantograph at the low speed of train. Finally, using the established analysis method, the evolution of contact forces was performed for a newly designed high speed R-bar and for its transition structure.



펨토초 레이저 Trepanned Drilling 방식을 이용한 스텐레스 스틸 박판 미세 홀 가공

강민기, 안윤준, 김태동, 이종훈, 김현덕, 이호

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.209-215

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Stainless steel is known as a corrosion-resistant material and this superior ability could be a desired property for a pinhole aperture operated in a corrosive environment and thereby be able to maintain both smoothness and a perfect circular shape in order to achieve precise beam alignment. Laser drilling has widely been preferred when placing holes into stainless steel due to its non-contact method of machining. In addition, this method is capable of performing delicate machining while inducing relatively low amounts of heat in the affected zone in comparison with other traditional machining techniques such as punching. Laser drilling is also beneficial for specimens having a thin thickness since manufacturing tolerances are minimal in this case. In this paper, we have attempted to produce holes of various diameters in 10 m thick stainless steel foil by using a femtosecond laser trepanned method. We have demonstrated these to be of perfect circular shape and adhering to low tolerance manufacturing by adjusting the beam parameters. In addition, holes with various diameters have been made by employing previously selected machining parameters and the viability of pinhole apertures fabricated by laser drilling have been evaluated.



알루미늄 6061합금의 파이버 레이저 용접특성에 관한 연구

김영곤, 권의표

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.216-221

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In this study, the laser welding experiments were performed with the 1 mm thickness of Al 6061-T6 using by 5 kW fiber laser welding system. The optimum laser welding condition of the lap joint has been investigated by analyzing the penetration depth and the porosity fraction through observation of the cross-sections. Based on the test results, the sound joint was obtained from the welding condition with the power of 2 kW and the focal position of -0.8 mm at the continuous laser welding speed of 2 mpm. Also, the tensile strength of the sound joint after heat treatment(170℃, 12hr) was increased almost 87% that of the base material. Especially, the fatigue test result of the sound joint showed that the fatigue cycle was 3×10 4 at the highest test load of 100 MPa.



엔진 크랭크축의 필렛 롤링 효과에 따른 구조적 특성 및 내구성 평가


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.222-227

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Crankshaft is one of the most important moving parts in internal combustion engine. In order to design more lighter and compacter crankshaft, strength and durability analysis is significant in evaluating the engine performance and lifetime as well as overall mechanical information. In this paper, structural analysis is performed to obtain the stress amplitudes and mean stresses at critical locations of crankshaft over the engine rotational speed. The load magnitudes are calculated by considering the firing pressure, inertia force, and torsional load. Next. using the stress results and the fatigue properties of the material, durability analysis is done to calculate the fatigue safety factors. As a result, the critical areas of the crankshaft were crank pin and journal’s fillet areas, and their safety factors satisfied the analytical criteria at all rotational speed by considering the fillet rolling effect.



수분오염 윤활환경 하에서 구름접촉 피로손상의 미시적 관찰

심충기, 김홍석, 신기훈, 정성균

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.228-234

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Rolling contact fatigue(RCF) is a major cause of failure that appears in components of rolling contacts. In the recent years, the fatigue propagation and failure have been an important issue in respect of the safe operation and to reduce the noise and vibration of the rolling contact components. The water-contaminated lubrication is known to be one of the significant factors that reduces the lifetime of the rolling contact components. Thus, in this study, the effect of water-contaminated lubrication environment on the rolling contact fatigue was investigated. Bearing life testing was performed in two different lubrication conditions (i.e. normal lubrication environment and water-contaminated lubrication environment). The effect of the debirs on the rolling contact fatigue could be eliminated by establishing the debris filter system. Microscopic features of the rolling contact surfaces were examined using energy dispersive spectrometry and non-contact 3D measurement system. In the case of the water-contaminated lubrication, the increase of surface roughness values up to 17.6% was observed. The oxidation state and pattern of the rolling contact surfaces were very different depending on the lubrication environment. It was also found that the bearing rating life, L10 , was decreased significantly in the watercontaminated lubrication condition. The amount of reduction was about 49.7%.



루버 각도에 따른 차량용 루버핀 열교환기의 성능에 대한 3차원 수치 해석

오영민, 이수룡

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.235-241

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In this study, a numerical approach for automotive louvered fin heat exchanger is carried out to investigate the effect of louvered angle on the heat transfer characteristics. The numerical simulation code STAR-CCM+ is utilized to calculate flow and temperature fields with polyhedral meshes. The results show that the flow efficiency is increased as the louver angle is high. Also, the outlet temperatures are nearly the same according to louver angles because the average Nusselt numbers are nearly equivalent regardless of louver angle.



필링머신의 롤러 지그 개발에 관한 구조해석

허윤영, 양영준

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.242-248

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Peeling machine has been industrially used to peel the metallic circular bar such as cast iron, cast steel, SUS series. Especially peeling process was reported to not ease in case of SUS series due to its high hardness. Structural analysis for roller jig in peeling machine was performed to evaluate the structural safety. For these purposes, stress, deformation and safety factor were investigated. As the results, maximum stress was occurred at shaft and maximum deformation was occurred at side plate in roller jig. Further since the minimum safety factor of top plate was 8.16 in case of guarantee pressure, it is considered that roller jig of peeling machine in this study was structurally safe.



이종재료를 사용한 3D 프린터용 히팅블록 개발


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.249-254

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In this study, the heating block for 3D printer has a problem that heat is transferred to the filament guide portion to dissolve the filament, thereby preventing the filament from being discharged quickly out of the nozzle. In order to solve these problems, the cladding with different thermal conductivity was fabricated and the heating block was manufactured. The properties of the fabricated clad material and the surface temperature of the fabricated heating block were measured and the following conclusions were obtained. As a result of modeling thermal analysis of the heating block made of the clad material developed in this study rather than the existing heating block, the surface temperature of the filament guide portion was predicted to be lower than the surface temperature of the heating portion. The shear strength of the clad material developed in this study was measured and the average value of 82.8 MPa was obtained. The thermal conductivity of the existing heating block was 237W/m K at 300K. The thermal conductivity of the heating block made of the clad material ⋅ developed in this study was 81.416W/m K, which is lower than the conventional thermal conductivity. The ⋅ surface temperature of the heating block made of the clad material developed in this study is 172.3℃, which is lower than that of the conventional heating block. Future research is to evaluate the thermal distribution by using a metal with a lower thermal conductivity than carbon steel and by cladding pressure, evaluating the physical properties of the clad material, and fabricating it as a heating block.



초초임계압 보일러 헤더용 P92 강 용접부의 고온 크리프 특성 평가


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.255-261

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P92 steel weldment scheduled to use for next generation ultra super critical(USC) boiler header is assessed on creep characteristics. The test method to assess local structure of weldment is small-punch creep(SP-Creep) test, which is a kind of micro test proved the availability on evaluation of mechanical property for local structure. The results for P92 steel weldment are compared with that of tensile creep test for same microstructures of steel weldment. Overall, the creep resistance of coarse grain HAZ(CGHAZ) at 650℃ is inferior to the other structures while fine grain HAZ(FGHAZ) is most superior in the P92 steel weldment. The power law relationships can be obtained for each weldment structures(BM, ICHAZ, FGHAZ, CGHAZ and W.M) of USC boiler header



직접분사식 디젤기관에서 연료첨가제와 EGR의 적용 특성 연구

최승훈, 김홍석

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.262-267

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This research aims to analyze the potential possibility of the butyl ether (BE, oxygenates of di-ether group) as a fuel additives for a naturally aspirated direct injection diesel engine fuel. Compared with the diesel fuel, smoke emission decreased approximately 26% by applying the blended fuel(diesel fuel 80 vol-% + BE 20vol-%) at the engine speed of 2,500 rpm and with full engine load. There was none significant difference between the blended fuel and the diesel fuel on the power, torque, and brake specific energy consumption rate of the diesel engine. But, NOx emission from the blended fuel was higher than that of the commercial diesel fuel. As a counter plan, the EGR method was employed to reduce the NOx. We found the possible area where the simultaneous reduction of the smoke and the NOx emission from the diesel engine was achieved by applying the BE blended fuel and the cooled EGR method.



파동합성에 의해 생성된 비선형 음장의 시뮬레이션 연구

정현조, 조성종

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.268-273

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Applications of nonlinear acoustics are getting popular in the field of nondestructive characterization of material microstructure and damage. Before the nonlinear acoustic technique is fully utilized, it is important to understand the behavior of nonlinear acoustic fields generated by finite amplitude excitation. A two wave mixing technique can be considered and the difference frequency component can be used to determine the nonlinear material properties. One important advantage of using the difference frequency component is known to minimize the source nonlinearity and to acquire low attenuating nonlinear signals. In this paper, the expression for the difference frequency sound beam is derived from the quasilinear theory of the Westervelt equation which includes the material nonlinearity, beam diffraction and material attenuation. Simulation results are presented and the beam properies are discussed in comparison with the behavior of the second harmonic beam fields.




CNT 기반 신소재를 적용한 극지 해양 분야 결빙 방지용 면상발열체 특성에 관한 연구


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.274-280

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This study is based on the screen printing method with heat resistant thin film as base material and development for expansion is proceeding. Therefore, it is convenient to be applicable to the installation and it will be possible to reduce the cost compared with the existing construction such as heat trace by 50% or more. As a result, it is possible to develop and commercialize the market for Polar ship, shipbuilding and offshore plants as it is possible to secure CNT(Carbon Nano Tube) based surface heating element and heating paste composition technology as a heating element material at a cryogenic temperature. It is expected that the efficiency will be great when this method is applied to other industries.



AZ60 마그네슘합금을 이용한 용접 공정별 접합부 특성 평가

김부민, 김인규, 이한섭, 박상흡

한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.281-285

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In this study, the mechanical characteristics with micro structure were analyzed on the butt joint of AZ60 magnesium material extruded by GMAW and GTAW processes. As the result of tensile test, the fracture in the welding joint area happened at both processes and seemed to be brittle fracture. The yield strength of GMAW was 84.29% and GTAW was 60.43% as compared with base metal. The yield strength of GMAW was higher 23.86% than that of GTAW. The result of decreased micro hardness was indicated at both processes. The value of minimum micro hardness in FZ at GMAW was Hv 46.7 and GTAW was Hv 43.6 as compared with base metal. The value of minimum micro hardness at GMAW process was higher 5.64 % than that at GTAW process. The size of grain boundary at GMAW process in HAZ is smaller than that at GTAW process. GMAW process is more superior than GTAW process from the productivity and quality in case of automatic welding for magnesium alloy such as the automobile seat frame.



드릴가공 냉각효율에 관한 고압 절삭유 공급조건 해석


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.286-291

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Cutting tools tend to wear gradually with progressing of machining process due to extremely high surface loads and temperature from the relative motions between tool and workpiece. Especially, the high cutting temperature is a dominant factor in the relation to tool life. High-pressure coolant has been reported as an effective method to prevent the severe wear from cutting temperature. This research investigates efficient supplying conditions of high-pressure coolant with the CFD results from a internal-flush drilling process. The flow rate of coolant is increased drastically up to three times under 70 bar compared to conventional way.



듀얼 A형 브릿지를 적용한 스톤 커팅머신 개발


한국기계기술학회 한국기계기술학회지 제19권 제2호 2017.04 pp.292-298

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The study is the development of stone processing machines for larger blocks of stone for more than 2 meters. The wire saw were replaced by the cutting of existing prototypes and employed as a new form of cutting tools equipped with industrial diamonds. In addition, a turn table was developed to enable the milling of large blocks of stone allowing them to spin. On the other hand, large processing machinery has been imported and used mostly by Chinese machinery and has caused many inconveniences in managing and using equipment. Therefore, it is difficult for domestic production products to remain unstable, thus maintaining the nation`s crumbling granite industry. As a result, it is uncomfortable to find domestic products, but it is difficult to maintain the domestic stone industry. Therefore, we look forward to the revitalization of the domestic stone industry through this development.


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