• 한국정밀공학회지
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• 제14권2호
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• pp.129-135
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• 1997

Experimental studies have been carried out to obtain uniform cups by one operation of backward extrusion. A lot of factors on dimensional accuracy of backward extruded cups are billet material, billet shape, punch shape, punch velocity, geometry of tool, tool material, and lubrication etc. In manufacturing cup-shaped parts by backward extrusion, it is very important to design the initial billet shape or the preform. The objective of this paper is to find that the shape of the initial billet is related to dimensional accuracy and also to manufacture the more accurate product simultaneously reducing the loss of material as forming the shape of the initial billet by means of upsetting.

• 한국기계가공학회지
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• 제17권6호
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• pp.61-67
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• 2018

The face milling cutter, which is mainly used for the face milling, is used to cut the Carbon steel(SM20C) in the machining center for 5 times and 10 times respectively. This study clarify the dimensional accuracy characteristics according to the number of fine machining varied the condition of cutting depth, table feed speed and spindle speed. Cutting depth is varied 0.05~0.2mm, table feed speed is varied 0.05~0.2mm/min and spindle speed is varied 1500~2500rpm. As a result, the dimensional accuracy was stable 6 times machining with table feed speed 150mm/min and 10 times machining with table speed 100mm/min and cutting depth 0.05mm regardless times of machining.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.330-333
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• 2000

Dimensional accuracy and surface quality are very important in rapid prototyping especially when the models are used for the production of tools. This paper presents the development of benchmarking part to investigate dimensional accuracy and surface finish. A new test part is designed to perform benchmarking of major rapid prototyping processes such as selective laser sintering, laminated object manufacturing, stereolithography apparatus, and fused deposition modeling. The test part design includes basic manufacturing features such as holes, walls, squares, cylinder and etc. In addition, the small features are included in order to evaluate the fine details that can be manufactured by a specific RP process. The CMM program that automatically measures different features in the test part is also developed. The evaluation of accuracy as well as surface roughness are discussed for major rapid prototyping processes.

• 대한산업공학회지
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• 제24권4호
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• pp.601-611
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• 1998

The machining accuracy of CNC machine tools will decrease the production lead time because the coordinate compensation of the tool path will be unnecessary to meet design specifications. Improving the accuracy of machined parts enhances the reliability and functionality of the assembly as well as the life of the product. Among various factors affecting the accuracy of machined parts, the ambient temperature is the major factor that refers to the temperature surrounding the machine and workpiece. In this study, an experiment was conducted to confirm the dimensional variations caused by changes in the ambient temperature. The ambient temperature resulted in overcutting when it increased. A developed pre-processor converts the CNC program to compensate the dimensional variations caused by temperature changes. This methodology can be used to determine the machining accuracy and improve the positioning accuracy of a machine tool.

• 한국지구과학회지
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• 제39권1호
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• pp.46-52
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• 2018

이 논문은 자체 개발된 드론을 이용하여 사진측량기술을 적용하여 3차원 수치지표면모델(DSM)개발 연구를 수행하였다. 이 DSM을 개발하기 위하여 제주도 지역을 선정하여 24장의 사진을 개발된 드론으로 직접 촬영을 수행하였다. 촬영된 사진의 정확한 3차원 좌표를 부여하기 위하여, 10개의 지표기준점(GCP)점을 선정하여 상대측위 지구위치시스템(DGPS)측량을 실시하였다. 사진의 정확도를 평가하기 위하여 3개의 GCP점을 선정하여 사진상의 좌표와 지상점의 좌표의 정확도를 비교하였다. 사진좌표계과 지상좌표계의 정확도를 평가한 결과 수평오차는 8.8-14.7 cm로 나타났으며, 연직오차는 12.4 cm로 나타났다. 이 정확도는 국토지리정보원(NGII)이 인정하는 1/1,000 수치지도의 정확도를 가지는 측량결과이다. 이 연구를 통하여 본 연구에서 개발된 드론과 사진측량기법이 제주지역에서 우리가 원하는 DSM자료를 얻는데 유용한 기술임을 알 수 있었다.

• The Journal of Advanced Prosthodontics
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• 제16권2호
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• pp.91-104
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• 2024

PURPOSE. The objectives of the current study were to estimate the influence of self-reinforced hollow structures with a graded density on the dimensional accuracy, weight, and mechanical properties of Co-Cr objects printed with the direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS. Sixty-five dog-bone samples were manufactured to evaluate the dimensional accuracy of printing, weight, and tensile properties of DMLS printed Co-Cr. They were divided into Group 1 (control) (n = 5), Group 2, 3, and 4 with incorporated hollow structures based on (spherical, elliptical, and diamond) shapes; they were subdivided into subgroups (n = 5) according to the volumetric reduction (10%, 15%, 20% and 25%). Radiographic imaging and microscopic analysis of the fractographs were conducted to validate the created geometries; the dimensional accuracy, weight, yield tensile strength, and modulus of elasticity were calculated. The data were estimated by one-way ANOVA and Duncan's tests at P < .05. RESULTS. The accuracy test showed an insignificant difference in the x, y, z directions in all printed groups. The weight was significantly reduced proportionally to the reduced volume fraction. The yield strength and elastic modulus of the control group and Group 2 at 10% volume reduction were comparable and significantly higher than the other subgroups. CONCLUSION. The printing accuracy was not affected by the presence or type of the hollow geometry. The weight of Group 2 at 10% reduction was significantly lower than that of the control group. The yield strength and elastic modulus of the Group 2 at a 10% reduction showed means equivalent to the compact objects and were significantly higher than other subgroups.

• Journal of Information Processing Systems
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• 제14권5호
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• pp.1167-1175
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• 2018

Microarray data plays an essential role in diagnosing and detecting cancer. Microarray analysis allows the examination of levels of gene expression in specific cell samples, where thousands of genes can be analyzed simultaneously. However, microarray data have very little sample data and high data dimensionality. Therefore, to classify microarray data, a dimensional reduction process is required. Dimensional reduction can eliminate redundancy of data; thus, features used in classification are features that only have a high correlation with their class. There are two types of dimensional reduction, namely feature selection and feature extraction. In this paper, we used k-means algorithm as the clustering approach for feature selection. The proposed approach can be used to categorize features that have the same characteristics in one cluster, so that redundancy in microarray data is removed. The result of clustering is ranked using the Relief algorithm such that the best scoring element for each cluster is obtained. All best elements of each cluster are selected and used as features in the classification process. Next, the Random Forest algorithm is used. Based on the simulation, the accuracy of the proposed approach for each dataset, namely Colon, Lung Cancer, and Prostate Tumor, achieved 85.87%, 98.9%, and 89% accuracy, respectively. The accuracy of the proposed approach is therefore higher than the approach using Random Forest without clustering.

• 소성∙가공
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• 제25권4호
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• pp.268-274
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• 2016

In the automotive seat industry, the use of a fine blanking press is important for manufacturing of high precision products. Among them, a gear part which is a main component of an automotive seat recliner is generally manufactured by fine blanking press. However, the use of conventional mechanical press has been increasing in manufacture of gear part because of low productivity of fine blanking press. In this study, new forming process is suggested to fabricate the gear part with high precision by using mechanical press. The effect of flow restriction die (FRD) which has the restriction of blank edge on dimensional accuracy is investigated by FE-analysis. FE-analysis results for different conditions of FRD indicated that FRD has high dimensional accuracy with the lowest roll-over and the highest perpendicularity of gear part. After application to fabrication of the gear part using mechanical press, the measured dimensional characteristic was compared with the required specification of final product. In addition, results of the performance test showed that the product fabricated by developed process satisfied the required strength and durability. The results show that the suggested forming process by using FRD and mechanical press can replace fine blanking on the viewpoint of dimensional accuracy and productivity.

• 한국정밀공학회지
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• 제25권7호
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• pp.55-63
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• 2008

Fine blanking is a process of press shearing which makes it possible to produce the thick sheet metal of the finished surface and the close dimensional accuracy over the whole material thickness in the single blanking operation. In this paper, a plate holder of automotive seat recliner is manufactured by FCF(Flow Control Forming) method using the conventional mechanical press instead of the fine blanking press. Main processes for manufacturing of the plate holder by FCF method are embossing, half blanking and trimming processes. Optimal clearance, stripper force and counter force to increase the dimensional accuracy of the plate holder have been investigated by FE-analysis. As a result of FE-analysis, the clearance for both embossing and half blanking processes was -2%t and the forces of stripper and counter were 25ton and 15ton, respectively. After manufacturing the plate holder by FCF method, the measured dimensional characteristics have been compared with the required specifications as the final product. Although the dimensional accuracy of the plate holder manufactured by FCF method was a little inferior to that by fine blanking process, it was satisfactory in a general sense.

• 대한인간공학회지
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• 제29권6호
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• pp.925-932
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• 2010

Most of the research on three-dimensional interaction field have showed different accuracy in terms of sensing, mode and method. Furthermore, implementation of interaction has been a lack of consistency in application field. Therefore, this study is to suggest research trends of three-dimensional interaction using meta-analysis. Searching relative keyword in database provided with 153 domestic papers and 188 international papers covering three-dimensional interaction. Analytical coding tables determined 18 domestic papers and 28 international papers for analysis. Frequency analysis was carried out on method of action, element, number, accuracy and then verified accuracy by effect size of the meta-analysis. As the results, the effect size of sensor-based was higher than vision-based, but the effect size was extracted to small as 0.02. The effect size of vision-based using hand motion was higher than sensor-based using hand motion. Therefore, implementation of three-dimensional sensor-based interaction and vision-based using hand motions more efficient. This study was significant to comprehensive analysis of three-dimensional motion recognition for interaction and suggest to application directions of three-dimensional interaction.