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이재령(Jaeryung Lee),김성진(Seong Jin Kim),박현달(Hyundal Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This paper describes the weight reduction technology of brushless DC (BLDC) motor with both advanced magnetic powder core instead of Si sheet steel core and copper cladding aluminum (CCA) instead of copper winding. In order to apply the high-density magnetic core for BLDC motor, the warm compaction process with die wall lubrication was used in this work. In general, the density of magnetic core is strongly associated with the core loss. The motor efficiency was improved as the magnetic core density was increased. Results showed that the oil pump motor using the advanced magnetic powder core was decreased about 10% in size and reduced about 10% in weight comparing to the convention motor with Si sheet steel core. Consequently, the motor and oil pump system containing the advanced powder core was satisfied the requirements during the performance and durability test.
김기정(Kijung Kim),김기범(Kibum Kim),김성진(Seong Jin Kim),박현달(Hyundal Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The novel PM (powder metallurgy) steel for automotive power-train gear components were developed to reduce manufacturing cost, while meeting the requirements. The high-density PM steel was manufactured by mixing using special Cr-Mo atomized iron powders, high-pressure compaction, and sintering. Tensile strength, charpy impact, bending fatigue, and contact fatigue tests for the PM steel were carried out comparing to the conventional forged steel. The pinion gears for 6-speed auto-transmission were also manufactured by helical pressing, sintering, and external rolling process (selective surface densification). In order to evaluate the durability of the PM parts, the auto-transmission durability tests were performed using dynamometer tests. Results showed that the PM steel fulfilled the requirements for pinion gears indicating suitable bending and contact fatigue strengths. The PM gears also showed improved gear tooth profile and better performance during the transmission durability tests. In particular, the PM gears manufactured by helical pressing and selective surface densification showed a significant advantage in reducing the manufacturing cost of about 30% as compared to the conventional forged steel gear manufactured by tooth machining (hobbing, shaving, and grinding) process.
Dualcasting 허브 일체형 브레이크 디스크 개발
이재영(Lee, Jae Young),이경돈(Lee, Kyung Don),박현달(Park, Hyun Dal),김성진(Kim, Seong Jin) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
A novel hub integrated brake disc is developed aiming reduction of its manufacturing cost and weight. This hub integrated disc is made of two different ferrous casting material of gray iron and ductile iron by specific dualcasting process and pattern design. As the friction part of the disc is closely related to performance and NVH in braking, it is normally made of gray iron. In the other hand, the hub integrated hat part is closely related to braking torque and the toughness. it is normally made of ductile iron. Specific time duration is required when pouring ductile iron after gray iron melt is poured into the mold to form stable interface between gray iron and ductile iron parts. In the green sand mold, two inlets are embodied to take two different types of casting melts into the mold. More accurate casting interface can be achieved by imparting melt reservoir(overflow) in the pattern design which is used for taking gray iron melt overflowing over the level of casting interface. Hub integrated brake discs had fulfilled mechanical strength test of the interface, brake torque test, and metallurgical analysis was done with the samples taken from the discs. As a result, this paper suggests novel concept of hub integrated brake disc manufactured by dualcasting process, and which is suitable for cost effective light weight brake system.
Studies on the Coating Materials for Forming Dies of Advanced High Strength Steel Sheets
Sungchul Cha(차성철),Hoyoung Kong(공호영),Iksoo Kim(김익수),Kunuk Park(박건욱),Hyundal Park(박현달) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
To increase the safety and lighten the weight of car body and chassis, the application of advanced high strength steel (AHSS) is being rapidly expanded. Current forming dies with thermal diffusion (TD) of vanadium carbide or coatings (AlTiCrN+MoS2, TiAlN) don’t have enough wear resistance and durability. The coatings shall have complex material properties, e.g. wear, temperature, fatigue resistance and low friction property. The main concept of coating and layer development is to add the low friction property through carbon addition to temperature resistant elements. The toughness, fatigue resistance and bonding are realized through nitrided layer, CrN or TiN and multilayer structure. Total 18 coatings are compared and discussed in this work. As conclusion, TiAlCN and AlTiCrN+CN show the competitive solutions.
홍채환(Chae-Hwan Hong),김세원(Se Won Kim),김용운(Yong-Woon Kim),박현달(Hyun-Dal Park),신현재(Hyun-Jae Shin) 한국생물공학회 2014 KSBB Journal Vol.29 No.5
Recently seaweed polysaccharides have been extensively studied for alternative energy application. Because their producing cost is high and efficiency low, their industrial applications have been limited. The main component of cell wall of red algae represented by Gelidiales and Gracilariales is agar. Red-algae agar or galactan, consisting of D-galactose and 3, 6-anhydro-L-galactose, is suitable for bio-product application if hydrolyzed to monomer unit. For the hydrolysis of algae, chemical or enzymatic treatment can be used. A chemical process using a strong acid is simple and efficient, but it generates together with target sugar and toxic compounds. In an enzymatic hydrolysis process, target sugar without toxic compounds generation. The objective of this review is to summary the recent data of saccharification by chemical and enzymatic means from red seaweed for especially focused on automobile industry.
자동차용 브레이크 디스크의 부식으로 인한 마찰특성의 변화에 대한 연구
한재민(Jaemin Han),조근형(Keun Hyung Cho),장호(Ho Jang),김성진(Seong Jin Kim),이재영(Jae-Young Lee),박현달(Hyun-Dal Park) 한국트라이볼로지학회 2005 한국트라이볼로지학회 학술대회 Vol.2005 No.11
Corrosion tests of discs were carried out in an environmental chamber, simulating in-vehicle situation, and torque variation during braking was measured using a single-end brake dynamometer. A friction model was introduced to confirm the pattern of torque variation. Ingredients in a friction material were substituted to series of springs and dashpots in this model. The velocity of the brake disc and the strength of the friction layer representing the existence of corrosion layer ware calculated as a variable. Results showed that the friction film and moisture content strongly affected the amount of corrosion. The dynamometer results also showed that the existence of the corrosion layer affected brake torque variation, and this result was confirmed by the friction model. The model showed that the amount of the torque variation increased when the corrosion layer existed and when the amount of ingredients with high stiffness increased at the fixed velocity. This suggested that the strength of corrosion layer and the transition of iron oxide particles were crucial factors for the corrosion induced torque variation.