Al7050합금의 단조 시제품 제작에 관한 연구

강성기(Seong-Ki Kang),이재근(Jea-Kun Lee) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.4

In this paper, process conditions are investigated for elimination of the grain coarsening and improved material flow during forging process by both of experiments and FEM analysis. Particular interest has been given to understand role of preform shape on the grain coarsening behavior and magnitude of the hammer forging load. As the results of FEM simulation by using DEFORM-3D, the simulated forging loads were 2,200ton in the case of a machined bar which is machined from 65㎜ to 60㎜ diameter, and below 1,900ton in the case of machined preform, respectively. The use of preform has been beneficial for reduction of the forging load and elimination of the grain coarsening. However, in the case of as received bar and the round bar, which was machined to 2.5㎜ thickness in surface layer, some degree of local grain coarsening behavior has been observed. The optimized preform shape could be properly designed by applying the FEM simulation.

초경 엔드밀의 플라즈마 이온 주입과 저온 열처리를 통한 내마멸성 향상

강성기(Seong-Ki Kang),왕덕현(Duck-Hyun Wang),김원일(Won-Il Kim) 한국생산제조학회 2011 한국생산제조학회지 Vol.20 No.2

In this research, nitrogen plasma source ion implantation(PSII) of non-coated tungsten carbide endmill tools was conducted with low heat treatment for increasing wear resistance. After the low heat treatment of PSIIed tools to give a homogeneity of wear resistance, the surface modification of tools was analyzed by hardness test, surface roughness and cutting forces. As for the resultant cutting forces, low heat treatment in temperature of 400℃ and 500℃ is stable because of low cutting resistance. The 20-minutes heat treated tool at spindle speed 25000rpm has superiority of surface roughness, Ra of 0.420㎛ and was found to have good wear resistance. The higher hardness value was obtained by increasing temperature from 300℃ to 600℃ for PSIIed tools with low heat treatment. As the PSIIed tools under 10minutes at temperature of 600℃ have the highest hardness as Hv of 2349.8, It was analyzed that temperature processing give much influences on hardness.

플라즈마 이온주입 공구의 가공조건이 절삭력과 표면 거칠기에 미치는 영향 분석

강성기(Seong Ki Kang) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.5

In this study, three dimensional cutting force components and surface roughness appeared in high speed cutting by using tungsten carbide endmill tools implanted ion or not found mutual relations through several analysis of statistical dispersion. It is showed that cutting force(Fx) is affect with spindle speed and feed rate, cutting force(Fy) is affect with spindle speed and ion implantation time and cutting force(Fz) is affect with feed rate in interaction through the statistical method of ANOVA of cutting force and surface roughness, it is analyzed that it is affected of spindle speed and feed rate in surface roughness.

WC-Co 공구의 이온 주입에 따른 표면층 및 가공된 표면거칠기 특성

강성기(Seong-Ki Kang),김영규(Yung-Kyu Kim),왕덕현(Duck-Hyun Wang),전영록(Young-Rok Chun),김원일(Won-Il Kim) 한국기계가공학회 2010 한국기계가공학회지 Vol.9 No.1

The most suitable condition for plasma source ion implantation(PSⅡ) was found based on the study of the characteristics of PSⅡed tool and machined surfaces. The depth analysis according to the chemical bonding state of elements and surface component elements through the XPS and SIMS, was conducted to find the improved property of the PSⅡed surface. Due to the diffusion of PSⅡ, the nitrogen was found up to a depth of about 150㎚ according to the supplied voltage and ion implanted time. The deep diffusion by nitrogen caused the surface modification, but the formation of oxide component was found due to the residual gas contamination on the surface. Statistical method of ANOVA was conducted to find the effects of spindle speed and feed rate in interaction for machined surface roughness with PSⅡed tools. The surface modification was found largely occurred by the nitrogen implanted surface with 2 hours for 27㎸, 35㎸ and 43㎸.

플라즈마 이온주입에 의해 표면 개질한 초경공구의 가공특성

강성기(Seong Ki Kang),왕덕현(Duck Hyun Wang),김원일(Won Il Kim) Korean Society for Precision Engineering 2010 한국정밀공학회지 Vol.27 No.1

In this research, the effects for surface Improvement of plasma ion implanted carbide endmill tools were observed by measuring cutting forces and tools wear affecting surface roughness in high speed cutting. From the 2nd ion mass analysis, the oxidation layer was found to be built up by sputtering. The residual gas contamination of oxygen was found to be contained impurities in nitrogen gas. The plasma implanted ion was found to be spreaded, especially the nitrogen was implanted up to 150nm depth as impressed voltage and ion implanting time. It is analyzed as bring surface improvement by spreading deeply forming oxidation on surface. The factors in Analysis of Variance(ANOVA) about mutuality cause reference of cutting force. The cutting force Fx is affected by the interaction of spindle rpm and federate, the cutting force Fy is influenced by spindle rpm and time injected ion, and cutting force Fz is affected by the interaction of impressed voltage and feedrate. Also, it was found that the cutting forces of implanted tools become lower and the surface roughness is improved by the effect of nitrogen according to the implantation.

비밀문서유통을 위한 보안 요구사항 분석

이지영,박진섭,강성기,Lee, Ji-Yeong,Park, Jin-Seop,Kang, Seong-Ki 대전대학교 군사연구원 2003 군사학연구 Vol.1 No.-

In this paper, we analyze the security requirement for a circulation of the classified documents. During the whole document process phases, including phases of drafting, sending/receiving messages, document approval, storing and saving, reading, examining, out-sending and canceling a document, we catch hold of accompanied threat factors and export every threat factors of security. We also propose an appropriate and correspondent approach for security in a well-prepared way. Last, we present the security guidelines for security architecture of the classified documents circulation.

MTS를 이용한 가압기 압력 제어 계통의 조기 고장 감지에 대한 연구

차재민,김준영,신중욱,염충섭,강성기,Cha, Jae-Min,Kim, Joon-Young,Shin, Junguk,Yeom, Choongseob,Kang, Seong-Ki 한국통계학회 2016 응용통계연구 Vol.29 No.7

원자력 발전소의 가압기는 1차 계통의 냉각재가 고온에서도 기화되지 않도록 압력을 가해주는 장치이다. 즉, 가압기의 고장은 원자력 발전소에 큰 영향을 미칠 수 있으며, 따라서, 가압기의 조기 고장 감지는 원자력 발전소의 안전에 매우 중요하다. 이를 위해, 본 연구에서는 마할라노비스 거리 개념과 다구찌 품질 공학 이론에 기반한 패턴 분류 인식 알고리즘 중 하나인 마할라노비스 다구찌 시스템(MTS)을 가압기 압력 제어 계통의 조기 고장 감지에 적용하였다. MTS의 고장 감지 성능을 검증하기 위해, 실제 원자력 발전소에서 발생하고 있는 가압기 압력전송기 고장 시나리오를 대상으로 하여, Full Scope 시뮬레이터를 통해 모사된 데이터에 적용하였다. 실험 결과, MTS는 단일 센서모니터링 기반의 전통적인 고장 감지에 비하여 매우 빠르게 고장을 감지할 수 있었다. A pressurizer is a major equipment system in a nuclear power plant (NPP) and controls the reactor cooling system pressure within the allowable range. Faults in the pressurizer can be critical to the NPP; therefore, early fault detection in the pressurizer is significant for NPP safety. This study applies Mahalanobis Taguchi system (MTS), which is one of the promising pattern classification methods, based on the Mahalanobis distance concept and Taguchi quality engineering theory to the early fault detection problem of the pressurizer pressure control system. We conducted experiments using data from full scope NPP simulator based on a pressurizer pressure transmitter faults scenario to validate the faults detection performance of MTS. As a result, MTS can rapidly detect the faults compared to conventional faults detection based on single sensor monitoring.

롤러 기어 캠의 시제품 가공특성에 관한 연구

김진수(Jin-Su Kim),강성기(Seong-Ki Kang),이동섭(Dong-Seop Lee) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.5

In the study, the effect grinding condition on the workpiece arithmetical average roughness(Ra) to 10 steps leading to cutting each section with the spindle rotational speed 8000rpm and feed rate 150mm/min of grinding in GC(green silicon carbide) grinding processing after heat treatment and non heat treatment of SCM415 material. Also the following conclusions were obtained analysis of stress distribution displacement and finite elements method(FEM) on assemble parts with 3+2 axis simultaneous control through grinding and gave a load 11kg on ATC arm both sides gave a load of 11kg. For the centerline average roughness(Ra) in the heat and non-heat treatment work pieces, which were appeared the most favorable in the fifth section were 0.511㎛ and 0.514㎛, that were shown in the near the straight line section was the smallest deformation of curve. In addition, the bad surface roughness appeared on the path is too long by changing angle, the more inclined depth of cut, because the chip discharging is not smoothly.

궤도 차량 로드 휠 강도평가와 잔류 변형에 관한 연구

신국식(Kuk-Sik Shin),강성기(Seong-Ki Kang) 한국기계가공학회 2011 한국기계가공학회지 Vol.10 No.3

A tracked vehicle is dependent on performance of power pack and suspension systems. Especially, road wheels which are components of suspension system contribute distributing vehicle weight on soil and preventing from misguiding tracks. In this study, the maximum force was calculated that a tracked vehicle is driven on the worst condition. And then, FE analyses were carried out to evaluate strength road wheel under maximum force condition. In standard of quality evaluation for road wheel, FE simulations and experimental works were carried out under thirty degree slant load of normal direction of shaft. And then, A relationship residual deformation for slant load was investigated. The result of this research is applicable to evaluate strength and to make use of basis data.

SCM415의 절단가공이 표면조도와 재료 두께에 미치는 영향

김진수(Jin-Su Kim),강성기(Seong-Ki Kang),신미정(Mi-Jung Shin) 한국기계가공학회 2013 한국기계가공학회지 Vol.12 No.2

This study focused on how it affects the surface roughness of work piece in cutting SCM415 steel, widely used steel in industry, by TiCN and TiN tools. Following conclusion was drawn from several experiments. The surface roughness of heat treated workpiece was better than that of non heat-treated materials. Moreover, the roughness of surface roughness(Ra 0.25) on feeding rate of 0.05 was better when it was in wet process, rather than dry process. As the feeding rate increases, TiCN coating tool shows better roughness of surface than TiN tool. Also, in heated treatment, TiCN coating tool shows the least straightness dimension deviation at feeding rate of 0.05, 0.15mm/rev, and concave-like R shape appears by the feeding rate orders of 0.05, 0.15, 0.1, 0.125 and 0.075mm/rev.