斷續切削에 있어서 切削抵抗과 工具壽命에 關한 硏究

梁均懿,남궁석 충남대학교 공업교육연구소 1980 論文集 Vol.3 No.2

The cutting resistance of grooved and non-grooved workpieces and the tool life under various cutting conditions was investigated experimentally with the use of a tool dynamometer. The results of this experiment are as follows : 1) The cutting force (principal and feed forces) increases with increasing depth of cut due to the force of the impact (force) between tool and workpiece in interrupted cutting. 2) The tool life of a P 20 cutting tool reduces with increasing feed cutting speed, and number of grooves. 3) The life of a P 20 tool is exceedingly short by comparision to the tool life of a H.S.S. tool in proportion to the increase of number of grooves.

연강 용접재의 부식피로 균열진전 거동에 관한 연구

나의균 군산대학교 1991 群山水産專門大學 硏究報告 Vol.25 No.1

This paper aims to clarify the effects of corrosive environment on crack growth for the weldment of the mild steel. Submerged arc welding was done and heat input was 30KJ/cm. Fatigue and corrosion fatigue tests were conducted at the frequency of 30Hz and stress ratio of zero. The results were summarized as follows. 1, Regardless of air and 3.5% NaCl solution, crack growth rate of the as-weld was slower than that of the parent because of the singularities at weld HAZ. 2. Fatigue life for the parent and the as-weld in corrosive environment increased in comparison with that obtained in air. 3. The increased fatigue life in corrosive environment is attributed to the crack closure which causes the stress amplitude to decrease. 4. The delayed rate (Nc/Na ; the radio of the number of cycles to failure in corrosive environment to that in air) for the as-weld was larger than that of the parent because of the crack closure and secondary cracks produced at HAZ.

HT-60강 용접부의 SCC 및 AE신호특성에 관한 연구

나의균,유효선,김훈 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.1

인공해수에서 HT-60강 용접부의 응력부식균열(SCC)과 음향방출(AE)신호특성을 알아보기 위하여 SCC와 AE실험을 동시에 실시하였으며, 양 실험결과를 상호 비교ㆍ분석하였다. 모재의 경우, -0.8V에서 보다 긴 파단수명을 보였고, 용해기구 등으로 인하여 -0.8V에 비해 -0.5V에서 AE가 많이 발생하였다. 그러나 시험편에 가해진 전위 값에 관계없이 최대하중 이후의 영역에서 AE 발생과 큰 진폭의 범위(40~100dB)를 나타내었으며 최대하중 이후에도 AE 발생이 활발하였다. 또한, 보다 크고 많은 균열이 파단면에 형성되었음을 SEM관찰을 통하여 관찰할 수 있었으며, 이들 결과로부터 용접부는 인공해수에서 SCC현상이 가장 심하게 일어나고 있음을 확인할 수 있었다. 후열처리는 용접부의 연화를 초래하였고, 용접재에 비해 부식환경에 대한 민감도를 떨어뜨리는 효과를 가져왔다. In order to characterize the microscopic fracture behaviour of the weldment during stress corrosion cracking(SCC) phenomena, SCC and acoustic emission(AE) tests were carried out simultaneously and the correlation between mechanical parameters obtained from SCC and AE tests was investigated. In the case of base metal, much more AE events were produced at -0.5V than at -0.8V because of the dissolution mechanism before the maximum load. Regardless of the applied voltages to the specimens, however, AE events decreased after the maximum load. In the case of weldment, lots of AE events with larger amplitude range(40~100dB) were produced because of the singularities of weld HAZ in comparison to the base metal and post-weld heat-treated (PWHT) specimens. Numerous and larger cracks for the weldment were observed on the fractured surfaces by SEM examination. From these results, it was concluded that SCC for the weldment appeared most severely in synthetic seawater. Weld HAZ was softened by PWHT which also contributed to the reduced susceptibility to corrosive environment in comparison to weldment.

음향방출법에 의한 고 장력강 용접부의 부식손상 특성 평가

나의균,김훈 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.3

본 연구의 목적은 음향방출법을 이용하여 고 장력강 용접부의 응력부식균열특성을 평가하는데 있다. 이를 위해 용접재와 후열처리재를 대상으로 인공해수에서 저 변형률로 하중을 가하면서 응력부식균열을 일으키고, 동시에 음향방출법에 의해 손상과정을 감시하였다. 부식환경은 전위계에 의해 제어되었으며, 시험편에는 각각 -0.8 V와 -1.1 V의 전위값을 가하였다. -0.8 V인 부식환경 하에서 일층 용접부는 후열처리재에 비해 단위 시간당 AE counts 수가 훨씬 많이 발생하였으며, 응력부식균열과정에서 균열의 발생 및 합체가 가장 활발하게 이뤄지고 있음을 누적 AE counts의 결과로부터 확인할 수 있었다. 가해진 전위 값이 -1.1 V인 경우, 일층 용접재의 파단시간은 이층 용접재에 비해 줄었고, AE counts수는 이층 용접재에 비해 현저히 많이 발생하였다. AE진폭 범위는 -0.8 V일층 용접재에서 가장 높았고, -1.1 V 일층 용접재에서 가장 작은 값을 보였는데, fractography분석결과 AE 진폭범위는 균열의 크기 및 폭과 밀접한 관계가 있음을 알 수 있었다. This study is to evaluate the characteristics of SCC at the welded region of high strength steel using acoustic emission(AE) method. Specimens were load by a slow strain rate method in synthetic seawater and the damage process was monitored simultaneously by AE method. Corrosive environment was controlled using the potentiostat, in which -0.8 Vand -1.1 V were applied to the specimens. In the case of one-pass weldment subjected to -0.8 V, much more AE counts were detected compared with the PWHT specimen. It was verified through the cumulative counts that coalescence of micro cracks and cracks for the one pass weldment with -0.8 V were mostly detected. In case of the one pass weldment subjected to -1.1 V, time to failure became shorter and AE counts were produced considerably as compared with that of the two pass weldment. It was shown that AE counts and range of AE amplitude have close relations with the number and size as well as width of the cracks which were formed during the SCC.

HT-80鋼 熔接材의 熔接後熱處理時 作用應力이 疲勞龜裂進展擧動에 미치는 影響

羅義均,吳錫炯 군산대학교 1992 群山水産專門大學 硏究報告 Vol.26 No.1

This study was conducted to examine the effects of the applied stress during PWHT on fatigue crack growth behaviours for the weldment of HT -80 steel. Stress during PWHT was applied to the weld HAZ in order to simulate the residual stress at welds. Submerged arc welding was done. Fatigue test was done at the frequency of 30Hz. The obtained data were analyzed between stress intensity factor range and crack growth rate. The fractured surface was observed by SEM and optical microscope. Crack growth rate of as -weld was slower than that of parent because of the singularities at HAZ. Crack growth rate for the specimen subjected to stress of 98Mpa was the fastest among PWHT specimens due to the precipitation of carbides which was formed during PWHT.

NC 가공을 위한 Ferguson 곡면의 오차 해석에 관한 연구

梁均懿,張鐘聲 全北大學校 1990 論文集 Vol.32 No.-

Sculputured surface are widely found in car body, ship hull and air plane parts. This paper covers computer-aided design of soulptured(or free-form) surface ; surface interpolation methods ; methods of generating CL-data for the machining of 3-D sculptured surface. The purpose of this paper is aimed to express how much we could show the real surface accurately comparing with the Ferguson surface used so many times, which is abtained from the 3-D point data through engineering calculation.

現行 算數敎育의 問題點과 그 對策 - 現場敎師 中心으로 -

申澤均,李義源 大邱敎育大學校 科學敎育硏究所 1988 과학·수학교육연구 Vol.12 No.-

旋削에 있어서 不均質被削材의 切削抵抗에 對하여

梁均懿,辛泰碩 충남대학교 공업교육연구소 1979 論文集 Vol.2 No.1

This paper describes that the cutting resistance of non-homogeneous workpiece siuch as mild steel having 6-4 brass fitted on 6 parts of grooved mild steel in turning operations with various cutting conditions by using tool dynanometer was investigated experimentally. The three components of cutting forces was recorded on the oscillograph, the size of workpiece was 50 ㎜ø × 300 ㎜ and Chemical composition of tool was w(18%) - Cr(4%) - V(1%). The results of this experiment are as follows; (1) The cutting forces increase with increasing depth of Cut, and feeds. (2) The cutting forces ( principal forces, feed forces) increase little by little till cutting velocity 60m/min, but the cutting forces increase rapidly from cutting velocity 60m/min to 110m/min and decrease from this point continously.

SS41강 다층용접부의 피로균열진전거동 평가에 관한 연구

羅義均 군산대학교 1993 群山水産專門大學 硏究報告 Vol.28 No.1

The purpose of this study is to evaluate the effects of PWHT on fatigue crack growth behaviours for the multi-passed weldments. Multi-passed weld was done using the submerged arc welder. Heat input per each pass was 30KJ/cm. Microstructure was observed by means of the optical microscope. Various kinds of microstructures through the midsection were produced due to the multi- passed welding process. Two kinds of specimens(0.5CT size, weld block) were given to PWHT(post weld heat treatment: PWHT). Fatigue test was conducted at the frequency of 3.3Hz with sine wave. The obtained data were analyzed from the view point of fracture mechanics. The crack growth behaviour was dependent upon PWHT conditions. In Paris's equation da/dN=C(ΔK)n, exponent value(n) for PWHT specimens increases and the vague of material constant(C) decreases compared with that for the as-weld.

가셋트-강관접합부의 극한관벽모멘트와 극한수직분력

신의균,윤석천 충남대학교 산업기술연구소 2000 산업기술연구논문집 Vol.15 No.1

In previous research, the behavior and strength of a gusset-tube joint subjected to axial and lateral loading was studied. From test results and analysis test results, main reasons of local buckling and local plastic deformation of tubular members were reviewed and the influence of degree of eccentricity on the ultimate strength was investigated. Therefore, to propose a practical design method to obtain the ultimate strength of a connection subjected axial and lateral forces, it was examined that lateral load is replaced by equivalent moment of tube-wall and normal component of the load. Mwu and Pvu ultimate strenth equation of gusset-tube joint will be proposed in this paper.