• Title/Summary/Keyword: Hard point

Search Result 609, Processing Time 0.03 seconds

Residual sterss and damaged layer in an intermittent hard turning (단속하드터닝에서 잔류응력과 가공변질층의 고찰)

  • 전준용
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
    • /
    • 2000.04a
    • /
    • pp.270-276
    • /
    • 2000
  • Hard turning has the potential to replace grinding process and to achieve significant reduction in production time and cost. The main applications for hard turning is finishing process, namely grinding process. Therefore, it must be able to satisfy high surface integrity of the workpiece. This paper discusses surface quality in terms of residual stress and damaged layer with respect to cutting parameters in an intermittent hard turning. Damaged layer experiment is carried out orthogonal array. From that is based on the orthogonal array. From the response table, cutting parameters are analyzed from the view point of the damaged layer and residual stress. From this experimental results, even though in the intermittent hard turning, surface integrity turns out be good enough for replacing grinding process.

  • PDF

A CEPHALOMETRIC STUDY ON THE SOFT-TISSUE PROFILE CHANCES FOLLOWING THE INCISOR RETRACTION (전치부 후방이동에 따른 연조직 측모 변화의 두부방사선 계측학적 연구)

  • Ha, Jeong-Kuk;Cha, Kyung-Suk
    • The korean journal of orthodontics
    • /
    • v.24 no.3 s.46
    • /
    • pp.547-554
    • /
    • 1994
  • This study was carried out in order to find out the soft tissue profile changes associated with maxillary incisor retraction in Angle's class I malocclusion patients. For this study fifty two female adult patients (Maximum Retraction Group 23, Minimum Retraction Group 29) who received orthodontic treatment were chosen. Following conclusions were obtained by analysing the changes of soft tissue and hard tissue before and after treatment. 1. When considering the mean changes of soft tissue and hard tissue, UP, LIP, Ls, Li (p<0.001), Point B, Si (p<0.01), Point A, Ss (p<0.05) were significant posterior movement in Maximum Retraction Group and UIP (p<0.001), LIP, Ls, Li (p<0.01), Point B, Si (p<0.05) were significant posterior movement in Minimum Retraction Group. 2. When considering the correlations between hard tissue and soft tissue changes, greater correlations were found in Minimum Retraction Group between UIP and Ls (p<0.01), Point A and Ss, UIP and Li, Point B and Si (p<0.05) than Minimum Retraction Group. 3. Correlations (p<0.01) were found between upper incisor retraction and posterior movement of the upper and lower lip in Thin Lip-Thickness Group, whereas no significant correlations were found in Thick Lip-Thickness Group. 4. Mean changes of the soft tissue thickness subsequent to incisor retraction were increased (p<0.01) in upper lip (Ls-Ls'), whereas no changes were found in lower lip.

  • PDF

A Study on Changes of Furniture Hard Ware in Korea - From the Joseon Era to Modern Times - (한국 가구 하드웨어 변화 연구 - 조선시대부터 현대까지 -)

  • Cho, Sook-Kyung;Moon, Sun-Ok
    • Journal of the Korea Furniture Society
    • /
    • v.23 no.2
    • /
    • pp.122-129
    • /
    • 2012
  • This article was intended as fundamental materials to recognize the current status of furniture hard ware in Korean market and to fix the identity of Korean furniture, by investigating and comparing the furniture hard ware used in the Joseon era and in modern times by type, function, shape and material. The analysis of furniture hard ware of the Joseon era and modern times from the view of functional aspects was oriented to the hard ware necessary to open and close the door & drawer on one side, and to that being attached to the main body of furniture not to scratch the wood by another wood on the other side, and from this the following conclusion was drawn. First of all, "Gwangdoojung" - a kind of spike- and metal decoration on the edge of the furniture disappeared, while the function-oriented hard wares have been diversified in modern times, from the perspective of the change of kinds. Second, the functional aspect of the furniture hard ware was emphasized in modern times than the Joseon era. In other words, the hard wares of the Joseon era came into view due to their strong appeal to decoration, whereas those of modern times were mostly hidden or moderated, keeping the function substantially. Third, the hard wares from the Joseon era were shown in concrete and detailed shape motivated by natural objects and furthermore even gloriously, but the modern hard wares are simple & basic geometry, from a formative point of view. Fourth, the material aspects present that the Joseon era's hard ware was mainly cast iron, whereas that of modern times shows the diversification from metal to even plastic. Finally, the recent trend in naming of the hard wares is the words of foreign origin. This resulted from that the foreign names of hard wares are valid also after import process in Korean market, so the domestic development of hard ware as the essential factor for the furniture design is urgently necessary to establish the identity of Korean modern furniture.

  • PDF

Soft tissue changes of upper lip and nose following posterosuperior rotation of the maxilla by Le Fort I osteotomy (Le Fort I 골절단술을 통한 상악의 후상방 회전에 따른 상순과 비부의 연조직 변화)

  • Kwon, Young-Wook;Pyo, Sung-Woon;Lee, Won;Park, Je-Uk
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
    • /
    • v.37 no.6
    • /
    • pp.457-463
    • /
    • 2011
  • Introduction: This study evaluate the soft tissue changes to the upper lip and nose after Le Fort I maxillary posterosuperior rotational movement. Materials and Methods: Twenty Skeletal class III patients, who had undergone bimaxillary surgery with a maxillary Le Fort I osteotomy and bilateral sagittal split ramus osteotomy, were included in the study. The surgical plan for maxilla was posterosuperior rotational movement, with the rotation center in the anterior nasal spine (ANS) of maxilla. Soft and hard tissue changes were measured by evaluating the lateral cephalograms obtained prior to surgery and at least 6 months after surgery. For cephalometric analysis, four hard tissue landmarks ANS, posterior nasal spine [PNS], A point, U1 tip), and five soft tissue landmarks (pronasale [Pn], subnasale [Sn], A' Point, upper lip [UL], stomion superius [StmS]) were marked. A paired t test, Pearson's correlation analysis and linear regression analysis were used to evaluate the soft and hard tissue changes and assess the correlation. A P value <0.05 was considered significant. Results: The U1 tip moved $2.52{\pm}1.54$ mm posteriorly in the horizontal plane (P<0.05). Among the soft tissue landmarks, Pn moved $0.97{\pm}1.1$ mm downward (P<0.05), UL moved $1.98{\pm}1.58$ mm posteriorly (P<0.05) and $1.18{\pm}1.85$ mm inferiorly (P<0.05), and StmS moved $1.68{\pm}1.48$ mm posteriorly (P<0.05) and $1.06{\pm}1.29$ mm inferiorly (P<0.05). The ratios of horizontal soft tissue movement to the hard tissue were 1:0.47 for the A point and A' point, and 1:0.74 for the U1 tip and UL. Vertically, the movement ratio between the A point and A' point was 1:0.38, between U1 tip and UL was 1:0.83, and between U1 tip and StmS was 1:0.79. Conclusion: Posterosuperior rotational movement of the maxilla in Le Fort I osteotomy results in posterior and inferior movement of UL. In addition, nasolabial angle was increased. Nasal tip and base of the nose showed a tendency to move downward and showed significant horizontal movement. The soft tissue changes in the upper lip and nasal area are believed to be induced by posterior movement at the UL area.

Energy Efficiency Analysis and Optimization of Multiantenna Heterogeneous Cellular Networks Modeled by Matérn Hard-core Point Process

  • Chen, Yonghong;Yang, Jie;Cao, Xuehong;Zhang, Shibing
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.14 no.8
    • /
    • pp.3366-3383
    • /
    • 2020
  • The Poisson point process (PPP) is widely used in wireless network modeling and performance analysis because it can provide tractable results for heterogeneous cellular networks (HetNets) analysis. However, it cannot accurately reflect the spatial distribution characteristics of the actual base stations (BSs). Considering the fact that the distribution of macro base stations (MBSs) is exclusive, the deployment of MBSs is modeled by the Matérn hard-core point process (MHCPP), and the deployment of pico base stations (PBSs) is modeled by PPP. This paper studies the performance of multiantenna HetNets and improves the energy efficiency (EE) of HetNets by optimizing the transmit power of PBSs. We use a simple approximate method to study the signal-to-interference ratio (SIR) distribution in two-tier MHCPP-PPP HetNets and derive the coverage probability, average data rate and EE of HetNets. Then, an optimization algorithm is proposed to improve the EE of HetNets. Finally, three transmission technologies are simulated and analyzed. The results show that multiantenna transmission has better system performance than single antenna transmission and that selecting the appropriate transmit power for a PBS can effectively improve the EE of the system. In addition, two-tier MHCPP-PPP HetNets have higher EE than two-tier PPP-PPP HetNets.

An Approximation Scheme For A Geometrical NP-Hard Problem (기하학적 NP-hard 문제에 대한 근사 접근법)

  • Kim, Joon-Mo
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.44 no.8
    • /
    • pp.62-67
    • /
    • 2007
  • In some wireless sensor networks, the sensor nodes are required to be located sparsely at designated positions over a wide area, introducing the problem of adding minimum number of relay nodes to interconnect the sensor nodes. The problem finds its form in literature: the Minimum number of Steiner Points. Since it is known to be NP-hard, this paper proposes an approximation scheme to estimate the minimum number of relay nodes through the properties of the abstract from. Reducing the number of nodes in a sensor network, the amount of data exchange over the net will be far decreased.

A Study on the Synthesis and Physical Properties of Polyurethane Elastomer (Polyurethane 탄성체(彈性體)의 합성(合成)과 물성(物性)에 관(關)한 연구(硏究))

  • Yoon, Jeong-Sik;Yoo, Chong-Sun;Paik, Nam-Chul
    • Elastomers and Composites
    • /
    • v.25 no.1
    • /
    • pp.13-19
    • /
    • 1990
  • The purpose of this study is to estabilish the synthetic condition of polyurhethane elastomer for excellent properties. Polyurethane elastomer which have different NCO percentage and hard segment contents was synthesized by casting method. And the effects of hard segment contents were investigated by analytical methods such as IR, DSC, etc. [NCO]/[OH] ratio was proper at the range $1.02{\sim}1.05$. By IR absorption peak($1250cm^{-1}$) which indicate interurethane hydrogen bond it was confirmed that hard segment were crystallized. Melting point that was determined by DSC showed the effects of hard segment contents, phase mixing and crystalline size.

  • PDF

The Transverse Dynamic Stability of Hard-chine Planing Craft

  • Lewandowski, Edward-M.
    • Journal of Ship and Ocean Technology
    • /
    • v.2 no.1
    • /
    • pp.1-12
    • /
    • 1998
  • A method to predict the dynamic roll stability of hard-chine planing craft is presented. Starting with the equation of motion, an equation governing small roll perturbations is developed. The roll restoring moment acting on the hull is evaluated by considering “static”and dynamic contributions. The contribution of rudders and skegs, which is significant for this type of craft, is also determined. A worked example is presented to show how the method can be used to find the maximum center of gravity height for transverse stability.

  • PDF

Kinematic Design Sensitivity Analysis of Suspension System Using a Symbolic Computation Method (기호계산 기법을 이용한 현가장치의 기구학적 민감도 해석)

  • 송성재;탁태오
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.4 no.6
    • /
    • pp.247-259
    • /
    • 1996
  • Kinematic design sensitivity analysis for vehicle in suspension systems design is performed. Suspension systems are modeled using composite joins to reduce the number of the constraint equations. This allows a semi-analytical approach that is computerized symbolic manipulation before numerical computations and that may compensate for their drawbacks. All the constraint equations including design variables are derived in symbolic equations for sensitivity analysis. By directly differentiating the equations with respect to design variables, sensitivity equations are obtained. Since the proposed method only requires the hard point data, sensitivity analysis is possible in suspension design stage.

  • PDF

Developemtn of Vehicle Dynamics Program AutoDyn7(II) - Pre-Processor and Post-Processor (차량동역학 해석 프로그램 AutoDyn7의 개발(∥) - 전처리 및 후처리 프로그램)

  • 한종규;김두현;김성수;유완석;김상섭
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.8 no.3
    • /
    • pp.190-197
    • /
    • 2000
  • A graphic vehicle modeling pre-processing program and a visualization post-processing program have been developed for AutoDyn7, which is a special program for vehicle dynamics. The Rapid-App for GUI(Graphic User Interface) builder and the Open Inventor for 3D graphic library have been employed to develop these programs in Silicon Graphics workstation. A Graphic User Interface program integrates vehicle modeling pre-processor, AutoDyn7 analysis processor, and visualization post-processor. In vehicle modeling pre-processor, vehicle hard point data for a suspension model are automatically converted into multibody vehicle system data. An interactive graphics capabilities provides suspension modeling aides to verify user input data interactively. In visualization post-processor, vehicle virtual test simulation results are animated with virtual testing environments.

  • PDF