• 한국공작기계학회논문집
• /
• 제11권6호
• /
• pp.1-9
• /
• 2002

This study describes the geometric characteristics and the 5-axis machining method in order to make end mill cutter coming with insert tips. End mill geometry is consisted of flute part and insert tip part. Flute part modeled by using ruled surfaces with constant helix angle, and insert tip part modeled by rectangular planes containing tapped hole of specified direction in its center. In this study, the modeled insert tip part considered both of a radial rake angle and a axial rake angle, because they were important cutting conditions. In order to machining the virtual end mill defined from geometric characteristics, we programmed a special software to machining the end mill considered in this study. This software can generate NC-codes about following processes, end milling or ball end milling of flute part end milling of rectangular plane, centering of hole, drilling of hole, and tapping of hole. Ant sampled end mills were modeled and machined on 5-axis CNC machining center with two index tables. Since machined end mills were very agreeable to designed end mills, we saw that the method proposed in this study can be very useful for manufacturing of end mill body with insert tip.

• 대한기계학회논문집
• /
• 제12권6호
• /
• pp.1252-1264
• /
• 1988

본 연구에서는 실제 산업현장에서 이용되고 있는 5자유도의 수직 다관절형 로 봇과 2자유도의 포지셔너를 하나의 기구학적 모델로 모델링하여 기구학적 해석을 하고 이때 발생하는 여유자유도제어 및 그 타당성을 검토하고자 한다. 이를 위하여 먼저 역기구학적 해를 여유자유도인 포지셔너의 틸팅(tilting) 관절각을 고정한 후 6자유도 의 로봇으로 모델링하여 해석적으로 구하는 방법을 제시하고, Jacobian행렬을 통해 특 이상태를 분석하고자 한다. 또한 여유자유도가 특이성회피를 목적으로 하는 R-P 시 스템의 작업성능에 어떠한 영향을 미치는가를 알기 위해 역기구학적 해로부터 구한 각 관절각을 Jacobian 행렬을 이용하는 조작성지수식에 대입하여 조작성지수를 얻고, 이 조작성지수의 등고선그래프로부터 높은 작업성능을 갖는 여유자유도 각을 구하고자 한 다. 아울러, 주작업 및 특이성회피를 목적으로 하는 부작업을 만족시키는 여유자유 도 제어방법의 경우에 높은 작업성능을 갖는 방향으로 관절각이 변화하는지를 역기구 학적 해만을 이용한 경우와 비교 검토하고자 한다.

• 대한의용생체공학회:의공학회지
• /
• 제24권4호
• /
• pp.247-257
• /
• 2003

This paper proposes a three-dimensional (3D) segmentation algorithm for extracting a diagnostic object from ultrasound images by using a LoG operator In the proposed algorithm, 2D cutting planes are first obtained by the equiangular revolution of a cross sectional Plane on a reference axis for a 3D volume data. In each 2D ultrasound image. a region of interest (ROI) box that is included tightly in a diagnostic object of interest is set. Inside the ROI box, a LoG operator, where the value of $\sigma$ is adaptively selected by the distance between reference points and the variance of the 2D image, extracts edges in the 2D image. In Post processing. regions of the edge image are found out by region filling, small regions in the region filled image are removed. and the contour image of the object is obtained by morphological opening finally. a 3D volume of the diagnostic object is rendered from the set of contour images obtained by post-processing. Experimental results for a tumor and gall bladder volume data show that the proposed method yields on average two times reduction in error rate over Krivanek's method when the results obtained manually are used as a reference data.

• Metals and materials international
• /
• 제24권6호
• /
• pp.1333-1345
• /
• 2018

The effect of manganese sulfide (MnS) inclusions on the machinability of free-cutting steel is based on their morphology, size and distribution. Furthermore, the plasticity of MnS is high during the hot working caused different characterization of MnS. In this study, the deformation behavior of MnS in 1215MS steel after a thermomechanical process was investigated at 1323 K. The microstructures of MnS inclusions were characterized by optical microscopy, scanning electron microscopy, energy-dispersive spectrometry, and electron backscattering diffraction (EBSD). As the thickness reduction of the inclusions increased from 10 to 70%, their average aspect ratio increased from 1.20 to 2.39. In addition, the deformability of MnS inclusions was lower than that of the matrix. The possible slip systems of A, B, C, and D plane traces were (${\bar{1}}0{\bar{1}}$)[${\bar{1}}01$], ($10{\bar{1}}$)[101], (011)[$01{\bar{1}}$], and (110)[$1{\bar{1}}0$]. Furthermore, the EBSD measurements suggested that slip planes in MnS inclusions occur on {110} planes.

• 지질공학
• /
• 제26권4호
• /
• pp.447-460
• /
• 2016

이 연구에서는 직접적으로 기본마찰각을 측정할 수 있는 직접전단시험과 삼축압축시험, 간접적으로 측정할 수 있는 기울임 시험을 이용하여 톱 절단면, #100 연마면, #600 연마면 등 총 3종류의 면을 갖는 황등 화강암과 Berea 사암의 기본마찰각을 측정하고 시험 결과들을 서로 비교하였다. 직접전단시험과 삼축압축시험에서 측정된 기본마찰각은 대체로 정확하지만 면의 상태에 따라서는 매우 차이가 나는 값이 측정되기도 한다. 기울임 시험은 모든 암종에서, 모든 면의 상태에서 유사한 결과를 산출하여 기본마찰각의 측정에 유용하게 사용될 수 있음을 보여주지만, 오차의 범위는 직접적인 시험에 비하여 비교적 넓은 범위를 보인다. 안정된 기본마찰각을 측정하기 위해서는 톱 절단면 보다는 전단면을 항상 일정하게 유지시킬 수 있는 연마면을 사용하는 것이 유리하며, 연마면 중에서도 #600 연마면 같이 매우 매끄러운 면 보다는 #100 연마면 같은 부드러운 수준의 면에서 보다 안정된 결과를 얻을 수 있다. 그러므로 #100 연마면 시료에서 직접전단시험이나 삼축압축시험으로 측정된 기본마찰각이 가장 신뢰성이 높을 것으로 예상되며, #100 연마면 시료에 대한 기울임 시험도 기본마찰각을 측정하는데 있어서 충분한 신뢰성을 갖는 것으로 판단된다.

• Journal of Biosystems Engineering
• /
• 제12권3호
• /
• pp.30-41
• /
• 1987

The geometrical shape of a plow bottom may be the most important factor affecting the performance of a plow for a given soil and operating conditions. There are various designs of the Jaenggi (Korean plow) available commercially, which may be different from each other and from the plow (Western plow) in respect to the shape and performance. This study was intended to investigate the geometrical characteristics of Jaenggi. The coordinate digitizer equipped with 3 potentiometers was designed and manufactured for measurement of the shape of curved plane of moldboard and share. The digitizer was connected to a microcomputer having the data acquisition system. This device was used to analyze the plow bottoms of 5 differently-made Jaenggis and one cylindrical plow. The results of the study are summarized as follows: 1. It was possible to measure easily and quickly the curved plane of plow bottom and to plot the view on three major plans using the coordinate digitizer electrically connected to a microcomputer system. 2. The shape of five Jaenggi bottoms analyzed could be characterized by the cutting angle having the range of $33-42^{\circ}$, the maximum share-lift angle of $41-50^{\circ}$, and the setting angle of moldboard wing of $46-70^{\circ}$. The most critical difference of the shape factors between the Jaenggi and the plow was found in the maximum share-lift angle, the former was more than twice as much as the latter. 3. The analysis of the shape of Jaenggi bottoms showed that the share projections on 3 major plans had a varied triangle, which was quite different from that of plow bottom. Especially, it was analyzed that the shape of furrow slice for the Jaenggi had a skewed rectangle, leaving a considerable height of the ridge at the furrow bottom. 4. The dihedral angle was similar range of $30-85^{\circ}$ for the all bodies investigated, but the directional angle was somewhat different from each other. The difference in directional angle was $5^{\circ}$ for the plow, $20^{\circ}$ for the Jaenggi A and $30^{\circ}$ for the Jaenggi B. 5. Area of the spherical representation region was 0.0328 for the plow, 0.1194 for the Jaenggi A and 0.1716 for the Jaenggi B. This may indicate that the plow came close to a working surface and the Jaenggi A and the Jaenggi B departed from a working surface to a somewhat greater extent.

• 한국전자파학회논문지
• /
• 제15권8호
• /
• pp.781-787
• /
• 2004

본 논문에서는 셀룰러/PCS/IMT-2000서비스를 동시에 수용할 수 있는 기지국용 다중대역 평판 안테나를 설계 및 제작하였다. 설계된 안테나는 두 개의 유전체 층과 폼 물질로 구성되었고 마이크로스트립 패치의 길이 방향과 너비 방향에 노치가 삽입되었다. 안테나의 광대역 특성을 위해서, 공진 개구면을 가지는 개구면 결합 안테나에 폼 물질을 사용하였으며, 패치의 너비 방향에 노치를 삽입하여 이중 공진 특성을 얻었다. 이를 통해, 광대역 특성을 유지하면서 주파수비( $f_{H/}$ $f_{L}$)가 1:2를 넘는 이중 공진 특성을 얻을 수 있었다. 설계된 안테나의 대역폭은 전압정재파비 1.5 이하로 셀룰러/PCS/IMT-2000 대역을 모두 만족하였고 측정된 안테나의 대역폭은 전압정재파비 1.5 이하로 셀룰러 대역에서 77 MHz, PCS/IMT-2000대역에서 550 MHz이며, 이득은 전 대역에서 약 5.65 dBi에서 7.4 dBi를 얻을 수 있었다.다.다.

• 한국의류학회지
• /
• 제31권5호
• /
• pp.692-704
• /
• 2007

Recently, Basic patterns with excellent body fitness and automation availability are required to be developed in order to automate the patterns of women's clothes. In this study, this reference points, reference lines and segments were fixed onto 3D scan data for the lower body the women in their twenties, they were directly spread out to be 2D flat pattern to facilitate development into the design of slacks adhered closely to the human body such as special and highly-functional clothes, and then slacks 2D pattern was developed for the purpose of seeking scientific approach to the development into basic form slacks and 3d emotional pattern. For conversion of 3D pattern into 2D flat pattern, reference points and segments were created by using Rapid Form of 3D shape analysis software, and triangle mesh of the body surface of the created shape was developed with Auto CAD 2005. The correspondence between slacks and human body was examined by the fixation of major reference lines. Specially, the wearing characteristics of slacks were considered by the fixation of side lines in consideration of posture. As a result of using the way of development to constantly maintain the length while 3D triangle mesh is converted into 2D flat mesh, the shape was shown to be excellently reproduced, and the area of flat pattern was increased compared to the shape of parting plane. Also, the sunk-in curve like the brief line of front crotch length needed a cutting line when it was closely adhered, when mesh was overlapped, and the pattern area was smaller compared to the actual shape.

• 대한기계학회논문집
• /
• 제17권8호
• /
• pp.2001-2011
• /
• 1993

This study deals with the machining of sculptured surfaces on 5-axis CNC milling machine with end mill cutter. The study (I) has the following contents. In 5-axis CNC milling, CL-data consist of CC-data and cutter axis direction vector at the CC-point. Thus, in machining of the sculptured surface on 5-axis CNC milling machine, determination of the direction vector of the milling cutter is very important. The direction vector is obtained by the fact that bottom plane of the milling cutter must not interfere with the free-form surface being machined. The interference is checked by the z-map method which can be applied in all geometric types of the sculptured surfaces. After generating NC part programs from 5-axis post-processing algorithms, sculptured surfaces were machined with 5-axis CNC milling machine (CINCINNATI MILACRON, 20V-80). From these machining tests, it was shown that the machining of the free-form surfaces on 5-axis CNC milling machine with the end mill has smaller cusp heights and shorter cutting time than on 3-axis CNC milling machine with the ball-end mill. Thus, 5-axis CNC end milling was effective machining method for sculptured surfaces. The study (II) deals with the prediction of cusp height and the determination of tool path interval for the 5-axis machining of sculptured surfaces on the basis of study(I).

• 한국지리정보학회지
• /
• 제5권4호
• /
• pp.24-34
• /
• 2002

본 연구의 목적은 DMZ 지역의 개발과 보전적 전략에서 생태적 평가를 수행하는데 있다. 군사적인 이유에 의해 연구지역을 현장조사하고 이를 바탕으로 생태적인 평가를 수행하기 어렵다. 때문에 본 연구에서는 Landsat ETM+ 위성영상 자료와 수치지도의 보조 자료를 이용하여 DMZ의 생태적 평가를 수행하였다. 생태적 영향권 조사를 위해 식생지수 가운데 하나인 NDVI값을 이용하였으며, 본 연구시점의 DMZ는 DMZ 내부를 제외하고는 식생활력도가 군사적 교란, 민간인의 영농활동 등으로 매우 낮은 값으로 나타났다. 또한 DMZ을 기준으로 설정한 거리별 식생지수값의 변화는 로지스틱한 형태로 표현되지 않고 있다. 이는 서부 및 중부지역의 평야지대의 경우 개발압력이 민통선지역에까지 이르렀으며, 동부지역의 경우 정기적인 사계청소의 영향이라 판단된다.