• Title/Summary/Keyword: straightness

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Acacia mangium Willd. - A Fast Growing Tree for Tropical Plantation

  • Hegde, Maheshwar;Palanisamy, K.;Yi, Jae Seon
    • Journal of Forest and Environmental Science
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    • v.29 no.1
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    • pp.1-14
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    • 2013
  • Acacia mangium is an evergreen fast-growing tropical tree, which can grow up to 30 m tall and 50 cm thick, under favorable conditions. It is a low-elevation species associated with rain forest margins and disturbed, well-drained acid soils. It is native to Papua, Western Irian Jaya and the Maluku islands in Indonesia, Papua New Guinea and north-eastern Queensland in Australia. Due to its rapid growth and tolerance of very poor soils, A. mangium was introduced into some Asian, African and western hemisphere countries where it is used as a plantation tree. A. mangium has good quality wood traits, such as a comparatively low proportion of parenchymatous cells and vessels, white and hard wood, and high calorific value. Therefore, it is useful for a variety of purposes, such as furniture, cabinets, turnery, floors, particleboard, plywood, veneer, fence posts, firewood, and charcoal. It is also being used in pulp and paper making because it has good pulp traits, with high yields of pulp, quality of kraft, and produces paper with good optical, physical and surface properties. Because there are significant provenance differences in growth rate, stem straightness, heartwood formation and frequency of multiple leaders, the productivity and quality also varies depending upon environmental conditions, so genetic improvement programmes have been undertaken in countries like Australia, India, Indonesia, Malaysia, the Philippines, Taiwan and Thailand. The programme includes provenance identifications and testing, plus tree selection and clonal multiplication, establishment of seed orchards and hybridization. The phenology, reproductive biology, fruit characteristics, silvicultural practices for cultivation, pest and diseases problems, production of improved planting stock, harvesting, wood properties and utilization have been discussed in this paper.

The blocking channel to reduce the performance decrease using the low correlation with cyclic delay scheme in LED-ID system (LED-ID 시스템에서 채널 차단에 따른 성능 열화를 줄이기 위한 저 상관 순환 지연 기법)

  • Lee, Kyu-Jin;Kim, Gui-Jung
    • Journal of Digital Convergence
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    • v.13 no.10
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    • pp.319-325
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    • 2015
  • We proposed the blocking channel to reduce the performance decrease using the low correlation with cyclic delay scheme in LED-ID system. LED-ID is based on the visible light to transmit the data. However, It is occurred the block channel by structure or environment of indoor for light of straightness. LED-ID system is degraded the performance by the block channel as loss of data, and burst error. To solve the block channel, the proposed system is overcome the burst error by low correlation among data, which is able to obtain the maximize time diversity gain to improve the performance of BER by cyclic delay scheme. The BER performance is evaluated by computer simulation according to channel parameter. The simulation results shows that proposed system gives much better performance than conventional system and constant cyclic delay scheme system.

Measurement and Active Compensation for 3-DOF Motion Errors of an Air Bearing Stage with Magnetic Preloads (자기예압 공기베어링 스테이지의 3 자유도 운동오차 측정 및 능동 보정)

  • Ro, Seung-Kook;Kim, Soo-Hyun;Kwak, Yoon-Keun;Park, Chun-Hong
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.2
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    • pp.109-117
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    • 2009
  • This paper presents a linear air bearing stage with compensated motion errors by active control of preloads generated by magnetic actuators with combination of permanent and electromagnets. A 1-axis linear stage motorized with a linear motor with 240mm of travel range is built for verifying this design concept and tested its performances. The three motions of the table are controlled with four magnetic actuators driven by current amplifiers and a DSP based digital controller. Three motion errors were measured combined method with laser interferometer and two-probe method with $0.085{\mu}m$ of repeatability for straightness error. The measured motion errors were modeled as functions of the stage position, and compensation were carried out with feedforward control because the characteristics of the motion control with magnetic actuators are linear and independent for each degree-of-freedoms. As the results, the errors were reduced from $1.09{\mu}m$ to $0.11{\mu}m$ for the vertical motion, from 9.42 sec to 0.18 sec for the pitch motion and from 2.42 sec to 0.18 sec for roll motion.

A Study on Optimization of Manufacture Conditions for Water Treatment Membrane by Using Electrospinning Method (전기방사법을 이용한 수처리용 막 제조 조건 최적화 연구)

  • Lee, Sang Hyun;Choi, Sung Yeol;Chang, Soon Woong;Kim, Sung Su
    • Journal of Korean Society of Environmental Engineers
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    • v.39 no.8
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    • pp.456-461
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    • 2017
  • In this study, nano fibers with various physical properties were materialized by using a variety of polymers [PAN (Polyacrylonitrile), PU (Polyuretane), PSU (Polysulfone)] which are raw materials of dope solution manufactured for electrospinning and solvents [NMP (N-methyl-2 pyrrolidone), DMF (Dimethylformamide)] and evaluated characteristics of their flux and SS (Suspended Solids) separation and then ascertained application of manufactured fibers as separation membrane for water treatment. In this study, analysis of surface of manufactured material was carried out through SEM analysis to ascertain the cause of flux and SS separation performance by checking diameter, uniformity and straightness of fiber. If additive is used in manufacturing nano fiber water treatment separation membrane, it is expected to solve problems such as membrane fouling and mechanical strength and to be used as basic factor for manufacturing separation membrane with catalyst function added.

Variation in Seed and Cone Characteristics of Loblolly Pine (Pinus taeda L.) Families in Southern Part of Korea

  • Lee, Hyunseok;Lim, Hyemin;Lee, Wiyoung;Jang, Kyunghwan;Kang, Junwon
    • Journal of Forest and Environmental Science
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    • v.34 no.1
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    • pp.82-86
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    • 2018
  • Loblolly pine (Pinus taeda L.) is widely distributed in the southern part of the United States and it has been used as a major economic species in the region due to its excellent growth and stem straightness. The tree also grows only in the southern part of Korea because it is susceptible to cold. Recently climate changes have had widespread impacts on forest trees. Thus, the use of good quality seeds is prerequisite for assessing assisted migration adaptation trial. In this study, we conducted to investigate its cone and seed characteristics of each family, which is expected to improve seeds productivity for planting valuable timber trees. A total of 14 families were selected from the experimental forest in Boseong, Jeonnam province in 1981. The seed production capacity was estimated to range from 87.2 to 129.4 among families and the average was 111.3. The number of aborted ovules was investigated in the range of 11.4 to 29.5 for the first test and 7.4 to 22.2 for the second test. The average number of empty and filled seeds was 1.4 and 79.2 per cone, respectively. Based on the results, we can conclude that there is a strong correlation between the number of fertile scale and the seed production ability.

A Study on the Measurement of Roundness Profile for Rotating Object Using Two Points in Succession Measuring Method (축차 2점법을 이용한 회전체의 진원도 프로파일 측정에 관한 연구)

  • Lee, Min-Ki;Lee, Eung-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.8
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    • pp.1029-1034
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    • 2010
  • In this paper, we present the roundness profile and run-out error measurement for a rotating shaft. The devices for measuring the roundness require a precision rotation table which is used as a reference to obtain the circular profile. Therefore, the roundness measuring system is expensive and requires precision manufacturing. The two-point method for succession measurement has been used to obtain a linear profile or used in straightness measurement using two displacement measuring devices. In this paper, the method is used for measuring the circular profile of a rotating shaft. A method to remove the vibration of the shaft, i.e., the run-out, is used, and the original circular profile is obtained from the measured raw data that excludes the run-out error of the rotating shaft. This method will be useful for obtaining the precise circular profile without using a precision reference circular artifact.

Development of Standard Test Specification for Hiking Stick (등산스틱 시험규격 개발 연구)

  • Kil, S.K.;Kim, J.H.;Kim, T.W.;Lee, S.C.;Hwang, J.H.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.9 no.4
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    • pp.309-317
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    • 2015
  • In this paper, we proposed the standard test specification for safety and function of hiking stick for the elderly. We have concluded nine factors representing specification of hiking stick through analysis of hiking patents and research papers, products survey of business market, case studies for damaged hiking stick and expert surveys. To test the factors, we designed three different kinds of apparatus to examine twist resistance, stick and tip durability and stick straightness. The sample of hiking sticks purchased from market based on Naver sales ranking top to fifteenth. As a result, we concluded six-standard test specification based on eccentric load, adjustable parts load, hand strap load, basket load, tip load and pull load of hiking stick.

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Modeling and Validation of 3DOF Dynamics of Maglev Vehicle Considering Guideway (궤도 선형을 고려한 자기부상 열차의 3자유도 동역학 모델 수립 및 검증)

  • Park, Hyeon-cheol;Noh, Myounggyu;Kang, Heung-Sik;Han, Hyung-Suk;Kim, Chang-Hyun;Park, Young-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.34 no.1
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    • pp.41-46
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    • 2017
  • Magnetically levitated (Maglev) vehicles maintain a constant air gap between guideway and car bogie, and thereby achieves non-contact riding. Since the straightness and the flatness of the guideway directly affect the stability of levitation as well as the ride comfort, it is necessary to monitor the status of the guideway and to alert the train operators to any abnormal conditions. In order to develop a signal processing algorithm that extracts guideway irregularities from sensor data, virtual testing using a simulation model would be convenient for analyzing the exact effects of any input as long as the model describes the actual system accurately. Simulation model can also be used as an estimation model. In this paper, we develop a state-space dynamic model of a maglev vehicle system, running on the guideway that contains jumps. This model contains not only the dynamics of the vehicle, but also the descriptions of the power amplifier, the anti-aliasing filter and the sampling delay. A test rig is built for the validation of the model. The test rig consists of a small-scale maglev vehicle, tracks with artificial jumps, and various sensors measuring displacements, accelerations, and coil currents. The experimental data matches well with those from the simulation model, indicating the validity of the model.

Permittivity Measurements of various Materials in 13-28GHz Band (13-28GHz 대역에서 다양한 매질의 유전율 측정)

  • Park, No-Uk;Jeong, Won-Ho;Jung, Myung-Won;Chong, Young-Jun;Kim, Jong-Ho;Kim, Kyung-Seok
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.14 no.1
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    • pp.161-167
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    • 2014
  • This paper presents the results of permittivities of various materials by measurements of the dielectric properties for the materials in millimeter-wave band. Since the advantages of millimeter wave band include the miniaturization, weight reduction of component and a lot of information transfer, its study has received increasing attention of researches. Also, because of the characteristics of the band have the superior straightness and the small diffractive, in the band, the analysis for the reflection and transmission characteristics of the materials will be very important. Moreover, a low interference is one of characteristics of the band due to the fact that the millimeter wave is absorbed in the materials. Therefore, in this paper, the reflection and transmission characteristics of materials are measured in the band by using the free space method. Based on the presented result, the permittivities of the materials are derived by the calculation of Nicolson-Ross Weir method.

Effect of Cholesterol-loaded-cyclodextrin in Presence and Absence of Egg Yolk during Freezing Step on Quality of Markhoz Buck's Spermatozoa

  • Farshad, A.;Amidi, F.;Khor, A. Koohi;Rashidi, A.
    • Asian-Australasian Journal of Animal Sciences
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    • v.24 no.2
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    • pp.181-189
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    • 2011
  • Cryopreservation protocols induce partially irreversible damage to mammalian sperm plasma membranes. Previous studies have indicated that adding cholesterol to the plasma membrane, as cholesterol-loaded-cyclodextrins, improves cryosurvival of sperm. Therefore, the purpose of this study was to determine if treating sperm of Markhoz bucks with cholesterol-loaded-cyclodextrins (CLC) (0, 0.75, 1.5, 2.25 and 3 mg/ml diluted $240{\times}10^6$ sperm/ml) in Tris-citric acid-glucose diluents with and without egg yolk (containing 5% glycerol) would improve the post-thaw sperm quality. The motion characteristics were evaluated with a Computer Assisted System Analyzer (CASA); acrosome integrity and vitality were measured with the triple-stain technique. Samples were recovered before and after freezing by means of putting straws into $37^{\circ}C$ water for 30 sec and then parameters were assessed. The results showed that the treatments significantly affected motility, progressive motility, recovery rate, curvilinear velocity, beat cross frequency, live sperm with reacted acrosome, live sperm with unreacted acrosome, dead sperm with reacted acrosorne, and dead sperm with unreacted acrosome during freezing (p<0.05). However; no significant differences were found for average path velocity, straight line velocity, amplitude of lateral head displacement, straightness and linearity (p>0.05). The best results were observed for extender containing 2.25 mg/ml ($240{\times}10^6$ sperm/ml) CLC supplemented with 2.6% egg yolk. In conclusion, the findings of this study indicate improved Markhoz sperm viability and motility following treatment in the presence of egg yolk.