쇼트피닝 가공에 의한 자동차용 Drive Plate의 내구성 향상

이국진,이동선,이재헌,정성균 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-

The effects of shot peening on the fatigue strength of SK-5M steel is investigated by experiment. The shot peening process is investigated optimum peening condition by changing impeller speed and exposure time. Bending fatigue test is accomplished to investigate the effect of optimum peening condition on the fatigue characteristics. As exposure time is increased, fatigue life in high stress is increased in early stage, become the maximum from 60 to 100 seconds, and then is decreased. Observing fracture surface through SEM after fatigue test, we can see clear configuration of cracks and peening layer.

부직포를 삽입한 Gr/Ep 복합재료의 인장특성에 관한 연구

이승환,임승규,정성균 서울産業大學校 産業大學院 1997 大學院論文集 Vol.5 No.-

In this paper, tensile properties of Gr/Ep with non-woven mat are investigated for effects to improve it. Composite materials are made by inserting non-woven glass mat and non-woven carbon mat between layers. The specimens were cut and polished according to ASTM standard. Longitudinal and Transverse Young's modulus are obtained by tensile test. Young's moduli without non-woven mat are compared with those with non-woven glass mat and non-woven carbon mat. Longitudinal and Transverse tensile strength, poisson's ratio are also investigated. Experimental results show that the longitudinal Young's modulus of composite materials with non-woven glass mat and with non-woven carbon mat is each about 16%, 23% lower than that of composite materials without non-woven mat. The longitudinal tensile strength of composite materials with non-woven glass mat and with non-woven carbon mat is each about 24% and 16% higher than that of composite materials without non-woven mat. And the transverse Young's modulus and tensile strength of composite materials with non-woven glass mat and with non-woven carbon mat is each about 10%, 35% higher than that of composite materials without non-woven mat. Longitudinal tensile strength of composite materials with non-woven carbon mat is about 10% higher than that of composite materials without non-woven mat. Longitudinal Pisson's ratio of composite materials with non-woven carbon mat is about 10% lower than that of composite materials without non-woven mat.

하악골 골절에 대한 임상통계학적 연구

이성훈,김기영,조규승,소광섭,박홍주,조요기,오희균,유선열 大韓顎顔面成形再建外科學會 1998 Maxillofacial Plastic Reconstructive Surgery Vol.20 No.1

會計情報시스템과 企業豫算모델

李九永,徐誠均 대구산업정보대학 1987 논문집 Vol.1 No.-

In modern business organization, computer is very important role for development accounting information system. Accounting information system is useful for all of management in modern enterprise planning and control activity. The purpose of this paper is to systematically illustate budgeting process, problem understanding on the process of budgeting and presentation of solving method, model establishment for rational budgeting. Theorytical background of this paper is accounting information system, modern accounting information system, traditional budget model, problem and solving method. The model of budgeting system on the basis of accounting information system theorytical background is Anthony's model, Habo's model, Mattessich's model. Now to conclude, we have need for total budgeting system in order to be greatest of accounting information utilization. Therefore, the new budget model must be development continuously.

결함을 갖는 기계부품의 표면가공에 따른 압축잔류응력의 영향 및 해석

이승호,서유원,정성균 서울산업대학교 산업대학원 2000 大學院論文集 Vol.7 No.-

Shot peening was applied on both smooth and notched specimen in order to investigate the stress distribution and the improvement in fatigue strength. The results shows that the fatigue strength of shot peened specimens increases by 34 percent compared to that of unpeened ones. Compressive residual stress also increased considerably, which resulted in the increase of fatigue strength. Finite element analysis showed that shot peening is effective in decreasing the bending stress by external force. the effectiveness of shot peening in reducing the compressive residual stress was anticipated by the superposition of the concentrated stress and the compressive residual stress.

기어의 생산성 향상을 위한 피닝공정의 실험적 연구

이재헌,이동선,정성균 서울産業大學校 2005 논문집 Vol.54 No.1

The shot peening process is well known technique for extending the durability of mechanical parts. We can expect the high cost and low fatigue life because the over peening process is applied in the industrial field. In this paper, the improvement of gear productivity was investigated by applying the optimum peening process. The experiment was accomplished for the SCM920 spur gear. Saturation curve and optimum peening condition were obtained by bending fatigue test. Experimental results show that the optimum peening time is between 6 minutes to 10 minutes. The improvement of productivity by optimum peening process was 36% higher than conventional process.

기어강의 표면가공에 따른 부식특성

이승호,서유원,정성균 서울산업대학교 산업대학원 2000 大學院論文集 Vol.7 No.-

The surface treatment to increasing corrosion resistance is becoming influence as very important technology. The influence of shot peening on the corrosion resistance of SCM 420 steel is investigated in this work. Then, surface compressive residual stress and hardness considerably increased, which resulted in the increase of corrosion resistance.

設計洪水量의 誘導를 위한 冪變換과 頻度分布分析의 比較

李淳赫,羅性均 충북대학교 농업과학기술연구소 1990 農業科學硏究 Vol.8 No.2

This study was conducted to pursue the normalization of frequency distribution by approaching the coefficient of skewness to zero through power transformation to the annual maximum series of four watersheds along Han, Guem, Nag Dong river basin. Analysis for the comparison of design flows according to the return periods were carried out between the best fitted probability distribution and power transformation. The results were analyzed and summarized as follows. 1. Power transformation has found to be best one in comparison with log and square root transformation for being the coefficient of skewness into closer zero as a means of getting the normalization of frequency distribution in the annual maxium series for the applied watersheds. 2. The best fitted probability was acknowledged as three paramater lognormal destribution for Jeong sun of Han, Im Ha of Nag Dong river basin and type 1 extremal distribution for Seok Hwa, Gyu Am of Geum river, respectively. 3. Empirical formulas for the probable flood flows and design flows according to the return periods were derivated for the applied watersheds. 4. Relative errors of three parameter lognormals and type 1 extermal distribution to power transformation which was acknowledged as a best fitted probable flows were shown to be within 10 percent in common for all watersheds from two to two hundred years of return period. 5. The part of higher nonexceedance probabilities, i.e. probable flood flows for power transformation leas found to be more approached to the observed data in comparison with the results of other fitted distributions in view of relative suitability.

會計情報시스템과 企業豫算모델

李九永,徐誠均 대구산업정보대학 1992 논문집 Vol.6 No.-

In modern business organization, computer is very important role for development accounting information system. Accounting information system is useful for all of management in modern enterprise planning and control activity. The purpose of this paper is to systematically illustate budgeting process, problem understanding on the process of budgeting and presentation of solving method, model establishment for rational budgeting. Theorytical background of this paper is accounting information system, modern accounting information system, traditional budget model, problem and solving method. The model of budgeting system on the basis of accounting information system theorytical background is Anthony's model, Habo's model, Mattessich's model. Now to conclude, we have need for total budgeting system in order to be greatest of accounting information utilization. Therefore, the new budget model must be development continuously.

쇼트피닝가공한 평기어의 최적 피닝강도 탐색에 관한 연구

이동선,이국진,김태형,정성균 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-

The shot peening process is often used to improve fatigue properties of metal parts. Among them, It is the most use in an auto-component. In order to achieve optimum, repeatable and reliable fatigue enhancement from the shot peening process, the important shot peening parameters must be controlled. In this paper, the optimum peening intensity (Almen intensity) condition is investigated by experiment..The Spur Gear steel was used to investigate shot peening effects. The fatigue life at σ_(a)=1,050 and σ_(a)=1,250MPa first gently increases, then drops gently as peening intensity increases compared with unpeened specimen. Experimental results show that the optimum peening intensity range is 0.391~0.434mmA..So the fatigue strength and fatigue life have been tremendously increased by optimum-peening treatment. However, the fatigue strength and fatigue life have been decreased by over peeing.