• Title, Summary, Keyword: Gap size

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The Pattern of Natural Regeneration by Canopy Gap Size in the Mixed Broadleaved-Korean Pine Forest of Xiaoxing'an Mountains, China

  • Jin, Guangze;Tian, Yueying;Zhao, Fengxia;Kim, Ji Hong
    • Journal of Korean Society of Forest Science
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    • v.96 no.2
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    • pp.227-234
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    • 2007
  • The forest canopy gap has been well known as a substantial process of forest cyclic regeneration and important role in stand structure, dynamics, and biodiversity of the forest ecosystem. Based on 3,600 $5m{\times}5m$ square grids in a 9ha permanent experimental plot, the study was conducted to evaluate the regeneration pattern of woody species by developmental stage {seedlings (<1 m of height), saplingI (>1 m of height, <2 cm of DBH), and saplingII (2 cm$<200m^2$), $201-400m^2$, $400-600m^2$, $601-800m^2$, and $>800m^2$) in the mixed broadleaved-Korean pine forest. The results indicated that the regenerating trees of Populus ussuriensis occurred only in the canopy gap area, considered to be a typical gap-dependent species. The regeneration of Ulmus japonica, Ulmus laciniata, and Maackia amurensis could be generally satisfied with the gap size of $201-600m^2$, Betula costata and Prunus padus with gap size of $401-800m^2$, Picea koraiensis with gap size of $201-800m^2$, Fraxinus mandshurica and Syringa reticulata var. mandshurica with smaller than $800m^2$, respectively. Acer ukurunduense and Acer tegmentosum were likely to have no problem with the gap size to make gap regeneration. Acer mono and Tilia amurensis looked more capable of regenerating in the closed canopy disregarding the upper crown condition. The regeneration of Pinus koraiensis and Abies nephrolepis had no trouble under the canopy condition in less than $800m^2$of gap size. The density of regenerating shrubs was rather high, especially under the closed canopy, considered to be associated with great amount of regeneration production in such shade tolerant species as Lonicera maackii, Corylus mandshurica, Euonymus pauciflorus, and Philadelphus schrenkii under the closed canopy. Pearson correlation coefficient was computed to compare the similarity among non-gap area and five gap size classes by developmental stages for trees and shrubs. The similarity coefficients among closed canopy and the gap size classes were mostly significantly correlated to each other with a few exceptions.

Laser Weldability and Formability of Hot Rolled Steels for Hydroforming Applications (하이드로포밍용 열연 강재의 레이저 용접성 및 성형 특성)

  • Lee Won-Beam;Lee Jong-Bong
    • Journal of Welding and Joining
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    • v.22 no.6
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    • pp.19-24
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    • 2004
  • The laser welding and its analysis of thin-sheet carbon steels were carried out with high power $CO_{2}$ laser. The main factor of weld quality of laser welding is gap and edge quality. This work was preformed to focus on the gap tolerance problem during laser welding. First, bead on plate welding of thin sheet was examined to investigate the effect of laser welding variables, and to obtain optimum welding condition. Butt welding was also carried out to show the effect of gap on the laser weldability of thin sheet. In order to investigate the effect of gap on formability of welded thin sheet, LDH test was caried out. At high welding speed, the partial penetration was obtained by low heat input. Otherwise, porosity was formed in the bead at low weld speed because of too much heat input. The optimum welding condition of welding was derived from bead width, penetration and hardness property. The maximum gap tolerance on laser welding was observed to be about 0.2mm. This gap size has good relationship with beam size of laser spot(about 0.3mm). The formability of welded sheet was about $80{\%}$ value of base metal and the gap size has not affected on the formability, although weld quality is dependent on the gap size.

Wage Gap and Determinants of Large and Small Enterprises (대기업과 중소기업 임금격차 및 결정요인)

  • Moo, Young-man
    • Journal of Labour Economics
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    • v.42 no.1
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    • pp.43-72
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    • 2019
  • As a result of decomposing the wage gap between large enterprises and SMEs using Oaxaca's wage gap decomposition method, the total wage gap of supply side factors was 44.2%, and the service years and educational background were the biggest influences. and As a result of decomposing the wage gap by firm size based on demand side factors such as business performance, total wage gap was 44.9%, and the influence on wage gap was in the order of labor productivity, union and outsourcing ratio. The results of this analysis suggest that it is necessary to consider the demand side factors such as business performance and capital structure of supply side companies such as differences in human capital in order to solve wage gap by firm size.

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Laser weldability and mechanical behavior of hot rolled steels for hydroforming applications (하이드로포밍용 열연강재의 레이저 용접성 및 기계적 특성)

  • 이원범;이종봉
    • Proceedings of the KWS Conference
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    • pp.84-86
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    • 2003
  • The laser welding and its analysis of thin-sheet carbon steels were carried out with high power CO$_2$1aser. Bead on plate welding of thin sheet was examined to investigate the effect of weld variables of laser welding, and to obtain optimum welding condition. Butt-welding was also carried out to show the effect of gap on the laser weldability of thin sheet. At high welding speed, the partial penetration was obtained by low heat input. Otherwise, porosity was formed in the bead at low weld speed because of too many heat input. The maximum gap tolerance on laser welding was observed to be about 0.2mm. This gap size has good relationship with beam size of laser spot(about 0.3mm). The formability of welded sheet was about 80% value of base metal and the gap size has not affected on the formability, although weld quality is dependent on the gap size.

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Recognition of Gap between base Plates for Automated Welding of Thick Plates (후판 자동용접을 위한 용접물의 갭 측정)

  • Yi, Hwa-Cho
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.4
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    • pp.37-45
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    • 1999
  • Many automated welding equipment are used in the industry. However, there are some problems to get quality welds because of the geometric error, thermal distortion, and incorrect joint fit-up. These factors can make the gap between base plates in case of a thick plate welding. The welding product with the quality welds can not be obtained without consideration of the gap. In this paper, the robot path and welding conditions are modified to get the quality weld by detecting the position and size of the gap. In this work, a low-priced laser range sensor is used. The 3-dimensional information is obtained using the motion of a robot, which holds a laser range sensor. The position and size of the gap is calculated using signal processing of the measured 3-dimensional information of joint profile geometry. The data measured by a laser range sensor is segmented by an iterative end point method. The segmented data is optimized by the least square method. The existence of gap is detected by comparing the data with the segmented shape of template. The effects of robot measuring speed and gap size are also tested. The recognizability fo the gap is verified as good by comparing the real joint profile and the calculated joint profile using the signal processing.

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Studies on Target Market of GAP Certified Raw-Ginseng (GAP 인증 수삼의 표적시장 연구)

  • Kim, Gwan-Hou;Lee, Ka-Soon;Yi, Doo-Hee;Hong, Seung-Jee
    • Korean Journal of Food Preservation
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    • v.18 no.5
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    • pp.684-691
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    • 2011
  • This study was carried out to suggest producers' marketing direction for GAP certified rawginseng using STP(segmentation, targeting and positioning). In order to fulfill this object, conjoint analysis and cluster analysis were used. The main results are as follows. Based on the results of part worth for attributes such as safety, size, and price, GAP certified raw-ginseng, large size, and low price were preferred to conventional ginseng, small size, and high price respectively. In the relative importance for each attributes, safety was 47.2%, size was 30.0%, and price was 17.8%. As a result of market segmentation, 3 consumer groups(large size preferred, safety preferred, lower price preferred) were classified. Among those groups, the safety preferred group was selected as a target market for GAP certified raw-ginseng and its market size was estimated approximately 2,968 tons which is 26.8% of total raw ginseng market.

The Effect of Gap Size on Counter Current Flow Limitation Phenomena in Narrow Annular Gaps with Large Diameter

  • Jeong, Ji-Hwan;Lee, Seung-Jin;Park, Rae-Joon;Kim, Sang-Baek
    • Nuclear Engineering and Technology
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    • v.34 no.4
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    • pp.396-405
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    • 2002
  • An experimental study on counter-current flow limitation phenomena in narrow annular passages was carried out The gap sizes tested were 1, 2 and 3 mm. This is very small compared with the outer diameter of the annular passage, 500 mm. It was visually observed that a CCFL might occur in some part of the periphery while the other part is remained in a counter current flow pattern. That is, non-uniform behaviour of fluids due 4o a 2-dimensional effect appear in a large diameter facility. Because of this non-uniformity, a CCFL is defined in the present work as the situation where net water accumulation is sustained. That is, some amount of water should not be allowed to penetrate the gap and accumulate over the gap at CCFL criterion. The measured data are presented in the form of Wallis'type correlation with characteristic length of gap size. It was found that the present correlation is in good agreement with other empirical correlation based on measurements whose test section diameter is close and the gap size is much larger than that of the present test section.

STUDIES OF CELL COMMUNICATION BY USING GAP JUNCTION CHANNELS RECONSTITUTE IN UNILAMELLAR LIPID VESICLES

  • Joe, Cheol-O
    • Proceedings of the Korean Biophysical Society Conference
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    • pp.6-6
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    • 1996
  • Gap junction channels were reconstituted into unilamellar liposomes using immunoaffinity purified connexin 32 gap junction protein from rat liver. Vesicles containing open channels and close channels were separated by means of iso-osmolar sucros density gradient sedimentation. The open channels formed in lipid vesicles were permeable to a fluorescent dye molecule, lucifer yellow of which the hydrodynamic size is similar to pore size of gap junctions in vivo. (omitted)

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Development of Gap Acceptance Models for Permitted Left Turn Intersections (비보호좌회전에서의 간격수락 행태모형 개발)

  • Lee, Chung Won;Lee, Dong Min;Hwang, Soon Cheon
    • International Journal of Highway Engineering
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    • v.18 no.5
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    • pp.95-103
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    • 2016
  • PURPOSES : Permitted left turn is a turning maneuver in which a vehicle turns left using a gap between oncoming vehicles, called gap acceptance, and it enables for more efficient traffic operation at intersections. In Korea, the permitted left turn has not been a common maneuver at signalized or un-signalized intersections. However, many experts and the Police Agency tried to apply this effective turning maneuver at intersections in Korea since 2010. Though the investigation of gap acceptance is significantly important in understanding a driver's behavior at intersections, there have not been many studies about this topic, specifically a study to develop probability models of gap acceptance behavior. METHODS : In this study, the probability model of gap acceptance behavior for a permitted left turn was developed based on observational field studies. To develop the model, seven variables were analyzed including gap, waiting time, traffic volume, conflict-flow vehicle type, left-turning vehicle type, the number of lane, and time. RESULTS : In the final model, gap and left-turning vehicle type were found to be significant influencing factors. CONCLUSIONS : Through this model development, it was concluded that as the gap size increased, the probability of gap acceptance was higher. Moreover, when a left-turning vehicle was a passenger car, the probability of gap acceptance was higher than compared to large size buses or freight cars.

Numerical Study of Gap Size Ratio Effect for Noncondensable Gas Ventilation in Condensers (응축기의 비응축 가스 배출 타입에 따른 틈 간격 비율의 영향에 대한 수치적 연구)

  • Je, Jun-Ho;Kim, Soo-Jea;Choi, Chi-Woong;Kim, Moo-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.1
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    • pp.67-74
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    • 2012
  • A numerical analysis was carried out to estimate the effect of the gap size ratio on the performance of condensers under noncondensable gas ventilation using the porous medium approach (PMA). In the PMA, the details of the tube bundle in the condenser are considered to be those of a porous medium, and the flow resistance term is added in the momentum equation. Three-dimensional analysis of the condensation for a McAllister condenser was conducted with the PMA using Fluent and user-defined functions (UDFs). The gap size effect on the condensation was negligible under pure steam conditions. However, the gap size effect was dominant in condensation with noncondensable gas and external venting. As the gap size decreased, the condensation rate increased for noncondensable gas in an external venting system.