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선삭에서 기계구조용 탄소강의 가공시 절삭저항과 표면거칠기에 미치는 영향에 관한 연구
신근하(Shin Keun Ha),이건준(Lee Gun Joon) 한국공작기계학회 1999 한국공작기계학회지 Vol.8 No.5
The purpose of this study was to der the effects of various cutting conditions on the cutting resistance and surface roughness of material in turning operation using a coated carbide tool. The workpiece materials were the carbon steel SM20C and SM45C. The results of this study are su㎜arized as follows: The cutting force decreases as the fee dee amount and the cutting depth decrease and the cutting speed increases. In order to obtain a proper surface roughness to each material, it is desirable to set the feeding amount as 0.059㎜/rev, the cutting depth as 0.4㎜ and the cutting speed as 270m/min for SM20C, while setting the feeding as 0.059㎜/rev, the cutting depth as 0.6㎜ and the cutting speed as 270m/min for SM45C.
맞대기 이음용접의 강도향상을 위한 어니일링 효과에 관한 연구
송삼홍,신근하,Shin, Keun-Ha 대한기계학회 1979 대한기계학회논문집 Vol.3 No.2
This paper presents the effect of stress relief annealing on mechanical properties in single Vee-groove welding joint. In this experiment, the investigation of annealing effect on mechanical properties of test material carried out by changing the annealing temperature from $600^{\circ}C$ to $900^{\circ}C$ under the given conditions. The results pbtained by this study are as follows: (1) Under the constant welding conditions, the tensile strength of test welded joint decrease in accordance with the increase of annealing temperature. The experimental results show that the reduction rate of tensile strength is about 35.09% of base metal strength. (2) Microhafdness distribution of welded joint bring about the maximum hardness near the bended line of welding joint. (3) Izod impact energy of welded joint in increase in according to the rise of annealing temperature and the peak energy of impact test occurs at $800^{\circ}C$
TS볼트체결에서 체결력 , 토오크계수 및 품질관리에 관한 연구
손승요(Seung Yo Son),신근하(Keun Ha Shin),최돈흥(Don Heung Choi),조인습(In Sub Cho),안교철(Kyo Chul Ahn) 한국강구조학회 1994 韓國鋼構造學會誌 Vol.6 No.3
TS(abridged from Torque-Shear) bolts are originaly developed for the purpose of quality assurance in clamping force by means of fracture mechanism due to the stress concentration around the V-type notch at the bolt tip. In the control of tightening a bolt, torque factor as well as geometries of the notch (diameter, angle and roundness) are of prime importance to assure the quality of the joint performance in a structure. Some theoretical aspects of fastening torque and clamping force in a TS bolt are examined with focus on the friction coefficients. A simple relationship between face friction coefficient and thread friction one is derived, and numerical calculations and plots based on the experimental data are presented, which may be used as a complementary guide in a situation to cope with torque factor degradation. It is found that the interaction between friction torque on the thread and the tensile force developed in a bolt leads to an elliptic stress space. The upper limit of thread friction coefficient μ_s and the lower limit of face friction coefficient μ_w are derived and plotted against the axial force ratio.
GIS와 RS를 이용한 토지피복 및 식생 분포의 시ㆍ공간적 변화 -평안북도 서부 지역을 중심으로-
이민부(Min-Boo Lee),김남신(Nam-Shin Kim),최한성(Han-Sung Choe),신근하(Keun-Ha Shin) 대한지리학회 2003 대한지리학회지 Vol.38 No.5
본 연구에서는 GIS 및 RS를 이용하여 평안북도 서부지역을 대상으로 1988년~2001년 사이의 토지피복과 식생 분포의 시·공간적 변화를 살펴보았다. 이를 위해, Landsat TM 및 ETM 영상을 사용하여, 기하 방사 보정 후, 감독 분류와 NDVI 분석을 실시하였다. 분석 결과, 평안북도 삭주, 대관, 구성, 의주 지역에서는 13년 동안 산림이 감소하고 시가지, 인간의 간섭에 의해 발생한 황무지, 범람과 사태 등의 자연적 요인에 의한 나대지 등이 증가한 것을 관찰하였다. 또한, DEM 분석을 통해 대부분 지역에서 고도가 높고 경사도가 큰 지역까지 시가지 개발 및 확장, 개간이 이루어지면서 더 많은 황무지가 발생하고, 비교적 높은 고도에서도 NDVI 값이 감소한 사실을 알 수 있었다. 이러한 변화는 지형적 특성을 고려하지 않은 채 이루어진 개발에 의한 것이며, 산사태 등의 자연재해 방지, 안정적인 식량공급 등을 위해 많은 연구 및 해결책 제시가 필요할 것으로 본다. This study deals with the spatio-temporal change of land cover and vegetation distribution between 1988 and 2001 using remote sensing images and GIS techniques in west area of Pyeongbuk Province, northwest Korea. Landsat TM and ETM images are geometrically and radiometrically corrected for the analysis of land cover and NDVI. Forested areas are decreased during 13 year from 1988 to 2001 in study area including Sakju, Daegwan, Guseong and Euiju of Pyeongbuk Province, because wasteland are increased by human impact and denuded land by landslide and flooding. DEM analysis presents that settlement and cropland are developed toward higher and steeper mountain slope, together with decrease NDVI values. these changes have resulted from unplanned increase of cropland without consideration of geomorphic condition. Therefore, more researches and reasonable policies are required to protect forest and cropland and stable food supply against natural hazard like landslide.