• Title/Summary/Keyword: Boring

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Effect of Strength Properties of In-Situ Concrete Pile in Embankment Slopes on Embankment Materials and Boring Methods (성토사면에 타설된 현장 콘크리트 말뚝의 강도특성에 미치는 성토재료 및 타설 방법에 대한 영향)

  • Hwang, Moo-Suk;Jeoung, Jae-Hoon;Park, Seung-Ki;Lee, Chang-Soo;Park, Chan-Gi
    • Journal of The Korean Society of Agricultural Engineers
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    • v.50 no.5
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    • pp.73-81
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    • 2008
  • This study evaluated the applicability of in-situ concrete pile as a stabilization materials of embankment slopes including agricultural reservoir and rural road etc. The experimental embankment slopes was constructed to investigate the strength properties of in-situ concrete pile with embankment materials and boring methods. The test variable were applied the boring method(driving and augering) and water-cement ratio. In order to analyze the physical and mechanical properties of embankment materials, permeability and water contents test were was performed. Also, the freshly and harden of in-situ concrete properties were measured by the slump and compressive strength tests. The results showed the water content and permeability of embankment materials and boring methods affected on compressive strength of in-situ concrete pile.

Composition and Abundance of Wood-Boring Beetles Inhabited by Pine Trees

  • Park, Yonghwan;Jang, Taewoong;Won, Daesung;Kim, Jongkuk
    • Journal of Forest and Environmental Science
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    • v.35 no.3
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    • pp.189-196
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    • 2019
  • Plants are consumed by a myriad of organisms that compete for resources. Direct interactions among multiple plant-feeding organisms in a single host can range for each species from positive to negative. Wood-boring beetle faces a number of biotic and abiotic constraints that interfere with the good prospects from the tree. Biotic factors, including arthropod pests and diseases, and abiotic factors, such as drought and water-logging, are the major constraints affecting the species. The present study aimed to provide basic data for analyzing forest health, identify the kinds of wood-boring beetles in the central part of Korea. Our second goal was to analyze the species composition and diversity of regional communities and to examine. A total of 10,461 individual wood-boring beetles belonging to 8 families and 50 species attracted to trap trees in the pine forests were recorded during the study period on study sites. The results of the analysis of collected species showed that the community structure on all study sites was similar. Seasonal occurrences of dominant wood-boring beetles (5 species) from each study site showed the highest number of all species, except for Siphalinus gigas in May, followed by a gradual decline, and the largest number of Siphalinus gigas appeared in June. The similarity index of species composition was relatively high, ranging from 0.75 to 0.90 for each study site.

A Study on the Dynamic Response Characteristics of Lathe Boring Bar (선반용 보링바의 동적응답특성 변동에 관한 연구)

  • Chun, Se-Ho;Ko, Tae-Jo
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.8
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    • pp.62-69
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    • 2010
  • Internal lathe machining with a boring bar is weak with respect to vibration because the bar is long and slender. Therefore, it is important to study the dynamic characteristics of a boring bar. The purpose of this study was to identify the effects of overhang and cutting conditions on the dynamic response characteristics of a boring bar. For an efficient experiment, an $L_g(3^3)$ orthogonal array was applied and the results were quantitatively analyzed by ANOVA. Overhang, feed per revolution, and depth of cut were selected as independent variables. Meanwhile, dynamic stiffness, damping ratio, damping coefficient, and acceleration were chosen as dependent variables. The vibration signal was obtained from an accelerometer attached to the boring bar, followed by visualization by a signal analyzer. The effect of overhang was found to have a significant effect on the dynamic stiffness, damping ratio, and damping coefficient, but the other variables did not. As the length of the overhang increased, the dynamic stiffness decreased and the damping ratio increased. In addition, the damping coefficient increased until the length of the overhang was 4D (where D is the shank diameter), after which it remained constant. The acceleration decreased until the overhang length was 4D, and then increased sharply when the overhang was increased further. From these results, the behavioral trend of the damping characteristics changed when its overhang length was 4D. Consequently, there is a critical point that the dynamic characteristics of boring bar change.

A Study on the Optimal Setting of Large Uncharged Hole Boring Machine for Reducing Blast-induced Vibration Using Deep Learning (터널 발파 진동 저감을 위한 대구경 무장약공 천공 장비의 최적 세팅조건 산정을 위한 딥러닝 적용에 관한 연구)

  • Kim, Min-Seong;Lee, Je-Kyum;Choi, Yo-Hyun;Kim, Seon-Hong;Jeong, Keon-Woong;Kim, Ki-Lim;Lee, Sean Seungwon
    • Explosives and Blasting
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    • v.38 no.4
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    • pp.16-25
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    • 2020
  • Multi-setting smart-investigation of the ground and large uncharged hole boring (MSP) method to reduce the blast-induced vibration in a tunnel excavation is carried out over 50m of long-distance boring in a horizontal direction and thus has been accompanied by deviations in boring alignment because of the heavy and one-directional rotation of the rod. Therefore, the deviation has been adjusted through the boring machine's variable setting rely on the previous construction records and expert's experience. However, the geological characteristics, machine conditions, and inexperienced workers have caused significant deviation from the target alignment. The excessive deviation from the boring target may cause a delay in the construction schedule and economic losses. A deep learning-based prediction model has been developed to discover an ideal initial setting of the MSP machine. Dropout, early stopping, pre-training techniques have been employed to prevent overfitting in the training phase and, significantly improved the prediction results. These results showed the high possibility of developing the model to suggest the boring machine's optimum initial setting. We expect that optimized setting guidelines can be further developed through the continuous addition of the data and the additional consideration of the other factors.

Study of Active Damping Boring Bar Using Piezoelectric Actuator for Small Boring Process (압전 액추에이터를 이용한 소구경 능동 방진 보링바 기초연구)

  • Guo, Yang-Yang;Hong, Jun-Hee;Song, Doo-Sang
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.4
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    • pp.658-664
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    • 2013
  • In this paper, we present a case study of vibration suppression based on the application of active damping to the small boring process of a boring bar with diameter below ${\Phi}12$. The proposed active damping system consists of an acceleration sensor for real-time monitoring of the vibration signal, a driver for phase control in a computer program, and piezoelectric actuators for damping. In this system, the vibration signals are detected by the acceleration sensor and sent to the computer as an input. The phase shift parameter of the natural frequency of the input signal is sent to the data acquisition board in the computer and calculated by the phase control program. This study confirmed the effectiveness of this damping system, and it opens up the possibility of the development of active damping systems for small boring processes.

A Study of the Boring Bar Vibration Measurement using Optical Fiber Sensor (보링바 고유진동 계측을 위한 광섬유 진동센서 연구)

  • Song, Doo-Sang;Hong, Jun-Hee;Jeong, Hwang-Young;Kang, Dae-Hwa;Kim, Byung-In
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.4
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    • pp.107-113
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    • 2009
  • In this paper, we studied of measurement the vibration of natural frequency using optical fiber sensor. The boring bar for measurement of vibration in use optical fiber sensor has the advantage of direct measure for the frequency than accelerometer. Because it deal with output value on electrical signal of optical fiber in physical disturbance when it measures the frequency of vibration. The optical fiber sensor measured the vibration of boring bar by the gap in sensing jig while optical fiber just kept contact with boring bar. A prototype system was composed of jig part with gap and optical system part. In this paper, we found out the possibility to measurement of vibration by the gap in use optical fiber.

Development of a GUI Program for the Design of a Vibration Control Boring Bar with a Tube-Type Structure (튜브 타입 제진용 보링바 구조설계를 위한 GUI 프로그램 개발)

  • Guo, Yang-Yang;Park, Jong-Kweon;Hong, Jun-Hee;Song, Doo-Sang
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.25 no.4
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    • pp.295-300
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    • 2016
  • In the design of passive and active boring bars, the structural dimensions and shape of the vibration control boring bar are modified depending on the diameter and depth of the workpiece, which changes the dynamic behavior. Thus, the natural frequency, effective mass, and stiffness for the main structure of a tube-type boring bar need to be reset for each vibration control case. However, commercial finite element method (FEM) software and experimental modal analysis are mostly used at present despite being too time-consuming. To overcome the weaknesses of the two methods currently used for vibration control, we realized a graphical user interface (GUI) program for the modal analysis of a modified tube-type damping structure. The analysis results with the GUI program were compared to those with commercial FEM software in order to confirm the effectiveness of the former.

연속계 해석에 의한 보오링바의 비선형 동적 거동

  • 박수길;강명창;김정석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.04b
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    • pp.137-141
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    • 1993
  • In the case of a boring bar, the vibration amplitude is generallylarge due to its high slenderness. The boring bat is then modelled as a cantilever with dynamic force acting at the free end and a generalized model of nonlinear continous system is obtained. The Analysis of model is conducted for the specific case with a zero side cutting edge angle. The dynamic behaviour is investigated for machining processes in which the the overlap factor of regenerative effect is considered. The vibration characteristics of boring bar depth of cut rather than feed rate in given slenderness.

A Study on the Change in Hole Precision with Slenderness Ratio of Boring Cutter (보링커터의 세장비에 따른 구멍 정밀도 변화에 관한 연구)

  • Chun, Se-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.5
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    • pp.7-12
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    • 2017
  • It is assumed that the buckling and cutting conditions depending on the slenderness ratio will affect the machining quality of the rotary boring tool mounted on a milling machine. In this study, the boring cutter was designed and fabricated to precisely create the Ø30 hole. Through the performance evaluation, the accuracy of the hole according to the slenderness ratio and cutting conditions was analyzed, and the following conclusions were obtained. The higher the RPM, the smaller the change in the working diameter, and the smaller the hole. Next, the smaller the slenderness ratio, the smaller the change in straightness due to the change in cutting conditions. Finally, the slenderness ratio also affects the tendency for changes in the concentricity. The larger the slenderness ratio, the more sensitive the concentricity to changes in cutting conditions.