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Identifying Roadway Sections Influenced by Speed Humps Using Survival Analysis (생존분석을 활용한 과속방지턱 영향구간 분석)

  • YOON, Gyugeun;JANG, Youlim;KHO, Seung-Young;LEE, Chungwon
    • Journal of Korean Society of Transportation
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    • v.35 no.4
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    • pp.261-277
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    • 2017
  • This study defines influencing sections as the part of the road section where passing vehicles are traveling with the lower speed compared to speed limit due to speed humps. The influencing section was divided into 3 parts; influencing section before the speed hump, interval section, and influencing section after the speed hump. This analysis focused on the changes of each part depending on installation types, vehicle types, and daytime or nighttime. For the interval section, especially, the ratio of distance traveled with lower speed than speed limit to interval section is defined as effective influencing section ratio to be analyzed. Vehicle speed profiles were collected with a speed gun to extract influencing section lengths. The survival analysis was applied and estimated survival functions are compared with each other by several statistical tests. As a consequence, the average length of influencing section on the 50m sequential speed humps was 75.3% longer during the deceleration than that of isolated speed hump, and 18.9% during the acceleration. The effective influencing section ratio for the 30m and 50m sequential speed humps had a small difference of 81.0% and 76.0% while the absolute values of the section that passing speed were less than the speed limit were longer on 50m sequential speed humps, each being 24.3m and 38.0m. Using the log rank test, it was evident that sequential speed humps were more effective to increase the length of influencing sections compared to the isolated speed hump. Vehicle type was the strong factor for influencing section length on the isolated speed hump, but daytime or nighttime was not the effective one. This research result can be used for improving the efficiency selecting the installation point of speed humps for road safety and estimating the standard of the distance between sequential speed humps.

The Flow-rate Measurements in a Multi-phase Flow Pipeline by Using a Clamp-on Sealed Radioisotope Cross Correlation Flowmeter (투과 감마선 계측신호의 Cross correlation 기법 적용에 의한 다중상 유체의 유량측정)

  • Kim, Jin-Seop;Kim, Jong-Bum;Kim, Jae-Ho;Lee, Na-Young;Jung, Sung-Hee
    • Journal of Radiation Protection and Research
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    • v.33 no.1
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    • pp.13-20
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    • 2008
  • The flow rate measurements in a multi-phase flow pipeline were evaluated quantitatively by means of a clamp-on sealed radioisotope based on a cross correlation signal processing technique. The flow rates were calculated by a determination of the transit time between two sealed gamma sources by using a cross correlation function following FFT filtering, then corrected with vapor fraction in the pipeline which was measured by the γ-ray attenuation method. The pipeline model was manufactured by acrylic resin(ID. 8 cm, L=3.5 m, t=10 mm), and the multi-phase flow patterns were realized by an injection of compressed N2 gas. Two sealed gamma sources of 137Cs (E=0.662 MeV, Γ factor=0.326Rh1m2Ci1) of 20 mCi and 17 mCi, and radiation detectors of 2"×2" NaI(Tl) scintillation counter (Eberline, SP-3) were used for this study. Under the given conditions(the distance between two sources: 4D(D; inner diameter), N/S ratio: 0.120.15, sampling time Δt: 4msec), the measured flow rates showed the maximum. relative error of 1.7 % when compared to the real ones through the vapor content corrections(6.1). From a subsequent experiment, it was proven that the closer the distance between the two sealed sources is, the more precise the measured flow rates are. Provided additional studies related to the selection of radioisotopes their activity, and an optimization of the experimental geometry are carried out, it is anticipated that a radioisotope application for flow rate measurements can be used as an important tool for monitoring multi-phase facilities belonging to petrochemical and refinery industries and contributes economically in the light of maintenance and control of them.

Earthquake impacts on hydrology: a case study from the Canterbury, New Zealand earthquakes of 2010 and 2011

  • Davie, Tim;Smith, Jeff;Scott, David;Ezzy, Tim;Cox, Simon;Rutter, Helen
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.8-9
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    • 2011
  • On 4 September 2010 an earthquake of magnitude 7.1 on the Richter scale occurred on the Canterbury Plains in the South Island of New Zealand. The Canterbury Plains are an area of extensive groundwater and spring fed surface water systems. Since the September earthquake there have been several thousand aftershocks (Fig. 1), the largest being a 6.3 magnitude quake which occurred close to the centre of Christchurch on 22February 2011. This second quake caused extensive damage to the city of Christchurch including the deaths of 189 people. Both of these quakes had marked hydrological impacts. Water is a vital natural resource for Canterburywith groundwater being extracted for potable supply and both ground and surface water being used extensively for agricultural and horticultural irrigation.The groundwater is of very high quality so that the city of Christchurch (population approx. 400,000) supplies untreated artesian water to the majority of households and businesses. Both earthquakes caused immediate hydrological effects, the most dramatic of which was the liquefaction of sediments and the release of shallow groundwater containing a fine grey silt-sand material. The liquefaction that occurred fitted within the empirical relationship between distance from epicentre and magnitude of quake described by Montgomery et al. (2003). . It appears that liquefaction resulted in development of discontinuities in confining layers. In some cases these appear to have been maintained by artesian pressure and continuing flow, and the springs are continuing to flow even now. In spring-fed streams there was an increase in flow that lasted for several days and in some cases flows remained high for several months afterwards although this could be linked to a very wet winter prior to the September earthquake. Analysis of the slope of baseflow recession for a spring-fed stream before and after the September earthquake shows no change, indicating no substantial change in the aquifer structure that feeds this stream.A complicating factor for consideration of river flows was that in some places the liquefaction of shallow sediments led to lateral spreading of river banks. The lateral spread lessened the channel cross section so water levels rose although the flow might not have risen accordingly. Groundwater level peaks moved both up and down, depending on the location of wells. Groundwater level changes for the two earthquakes were strongly related to the proximity to the epicentre. The February 2011 earthquake resulted in significantly larger groundwater level changes in eastern Christchurch than occurred in September 2010. In a well of similar distance from both epicentres the two events resulted in a similar sized increase in water level but the slightly slower rate of increase and the markedly slower recession recorded in the February event suggests that the well may have been partially blocked by sediment flowing into the well at depth. The effects of the February earthquake were more localised and in the area to the west of Christchurch it was the earlier earthquake that had greater impact. Many of the recorded responses have been compromised, or complicated, by damage or clogging and further inspections will need to be carried out to allow a more definitive interpretation. Nevertheless, it is reasonable to provisionally conclude that there is no clear evidence of significant change in aquifer pressures or properties. The different response of groundwater to earthquakes across the Canterbury Plains is the subject of a new research project about to start that uses the information to improve groundwater characterisation for the region. Montgomery D.R., Greenberg H.M., Smith D.T. (2003) Stream flow response to the Nisqually earthquake. Earth & Planetary Science Letters 209 19-28.

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Simulation of Groundwater Flow and Sensitivity Analysis for a Riverbank Filtration Site in Koryeong, Korea (경북 고령군 강변여과 취수 지역의 지하수 유동 모사 및 민감도 분석)

  • Won, Lee-Jung;Koo, Min-Ho;Kim, Hyoung-Su
    • Journal of Soil and Groundwater Environment
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    • v.11 no.2
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    • pp.45-55
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    • 2006
  • A 2-D unconfined flow model is developed to analyze annual variations of groundwater level and bank filtration rate (BFR) for an experimental riverbank filtration site in Koryeong, Korea. Two types of boundary conditions are examined for the river boundary in the conceptual model: the static head condition that uses the average water level of the river and the dynamic cyclic condition that incorporates annual fluctuation of water level. Simulations show that the estimated BFR ranges 74.387.0 annually with the mean of 82.4% for the static head boundary condition and 52.798.1 with the mean of 78.5% for the dynamic cyclic condition. The results illustrate that the dynamic cyclic condition should be used for accurate evaluation of BFR. Simulations also show that increase of the distance between the river and the pumping wells slightly decreases BFR up to 4%, and thereby indicate that it is not a critical factor to be accounted for in designing BFR of the bank filtration system. A sensitivity analysis is performed to examine the effects of model parameters such as hydraulic conductivity and specific yield of the aquifer, recharge rate, and pumping rate. The results demonstrate that the average groundwater level and BFR are most sensitive to both the pumping rate and the recharge rate, while the water level of the pumping wells is sensitive to the hydraulic conductivity and the pumping rate.

A Study of the Butterfly Community of Mt. Gyeryong National Park, Korea (계룡산국립공원의 나비류 군집에 관한 연구)

  • Jeon, Sung-Jae;Cho, Young-Ho;Han, Yong-Gu;Kim, Young-Jin;Choi, Min-Joo;Park, Young-Jun;Nam, Sang-Ho
    • Korean Journal of Environment and Ecology
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    • v.26 no.3
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    • pp.348-361
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    • 2012
  • Altitude is a factor that plays an important role in the diversity, richness and composition of species. Recently, much attention has been paid to the distribution of butterflies and insects according to altitude. The purpose of this article is to propose a method to preserve and manage species efficiently by reviewing the distribution of butterflies according to different altitudes in Mt. Gyeryong National Park. This study found that the number of species and individuals decreased as the altitude increased, possibly due to the increased amount of shade caused by the crown density. When analyzing the factors influencing the distribution of species other than altitude, it was found that the slope, vegetative colonies and hydrosphere distance were correlated with the change in species distribution. As these species are closely related to food plants, it may save time and reduce the cost as well as allow an efficient evaluation of the bio-diversity if these species are selected as biological indicator species suitable for detecting the changes in the forest. It is judged to be a more efficient means of species preservation to accumulate and quantify the materials regarding environmental elements such as the climate, microclimate and food plants, as this would allow the butterfly distribution to be estimated.

A Study on the Marine Traffic Risk Assessment by using Ship Handling Simulator (선박조종 시뮬레이터를 이용한 해상교통 위험도 평가에 관한 연구)

  • Park, Young-Soo;Kim, Jong-Sung;Kim, Chol-Seong;Yong, Jeong-Jae;Lee, Hyong-Ki;Jeong, Eun-Seok
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.19 no.2
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    • pp.138-144
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    • 2013
  • Large and small marine accidents which are related to vessel's navigation are happening continuously and these maritime accidents have caused loss of lives and properties, and serious maritime environmental pollution damage. It is also true that maritime pollution damage is increasing due to these accidents, probability of growth of seaborne volume and complicated maritime traffic environment. Korea, recently, is developing an evaluation index which can assess sea risk through the evaluation of maritime traffic environment and provide danger and general information with relation to maritime traffic environment on target sea area to evaluate maritime traffic safety. In this paper, we intend to confirm the validity of maritime traffic safety on the basis of vessel navigator's risk consciousness and various sailing conditions by using the ship handling simulator. To confirm the validity of sailing vessel's maritime traffic safety, we use analysis of variance. By using analysis of variance, we analyze vessel navigator's characteristics, distance, speed and encounter type between vessels. Through multiple comparison of each factor's risk difference, we can confirm the change of numerical value of risk difference in statistical aspect.

Influence of High Temperature of the Porcelain Firing Process on the Marginal Fit of Zirconia Core (도재 소성 과정에서의 고온이 지르코니아 코어의 변연적합도에 미치는 영향)

  • Kim, Jae-Hong;Kim, Ki-Baek
    • Journal of dental hygiene science
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    • v.13 no.2
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    • pp.135-141
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    • 2013
  • One factor for successful prognosis of finished dental prosthesis is good marginal fit. The purpose of this study in vitro investigation was to compare the marginal fit of all-ceramic crown before and after porcelain veneering, to evaluate the influence of high temperature of the porcelain firing on the fit. For this experiment, model of abutment tooth of maxillary right central incisor was prepared. Ten working models were produced. Ten zirconia cores were made by dental computer aided design/computer aided manufacturing system. The marginal fit of specimens were examined using silicone replica technique. Silicone replicas were sectioned four times and were measured through a digital microscope (×160). Marginal fit is a distance connected between edge end part of specimen and abutment margin. Each specimens was measured twice, the first measurement was done prior to veneering porcelain firing, while the second measurement was done after the porcelain firing to evaluate this process. Statistical analyses were performed with paired t-test. Mean±SD marginal fit was 60.8±14.2μm for zirconia core and 86.1±13.3μm for all-ceramic crown. They were statistically significant differences (p<0.001). But all specimens showed a marginal fit where the gap widths ranged within the clinical recommendation (120μm), all-ceramic crown production using the zirconia core was adequate.

A Study of Optimal path Availability Clustering algorithm in Ad Hoc network (에드 혹 네트워크에서 최적 경로의 유효성 있는 클러스터링 알고리즘에 관한 연구)

  • Oh, Young-Jun;Lee, Kang-Whan
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2012.05a
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    • pp.278-280
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    • 2012
  • We are propose the position of the node context-awareness information and the validity of the head node in the path according to the clustering how to elect one of the energy efficiency ECOPS (Energy Conserving Optimal path Schedule) algorithm. Existing LEACH algorithm to elect the head node when the node's energy probability distribution function based on the management of the head node is optional cycle. However, in this case, the distance of the relay node status information including context-awareness parameters does not reflect. These factors are not suitable for the relay node or nodes are included in the probability distribution, if the head node selects occurs. In particular, to solve the problems from the LEACH-based hierarchical clustering algorithms, this study defines location with the status context information and the residual energy factor in choosing topology of the structure adjacent nodes. ECOPS algorithm that contextual information is contributed for head node selection in topology protocols. The proposed ECOPS algorithm has the head node replacement situations from the candidate head node in the optimal path and efficient energy conservation that is the path of the member nodes. The new head node election show as the entire node lifetime and network management technique improving the network lifetime and efficient management the simulation results.

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A Study on the Ground Surface Area Calculation of Golf Course using Triangulated Irregular Network (불규칙 삼각망을 이용한 골프장의 지표면적 산출에 관한 연구)

  • Kim, Sang-Seok;Chang, Yong-Ku;Kwak, Jae-Ha;Kim, Youn-Soo
    • Journal of the Korean Association of Geographic Information Studies
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    • v.4 no.4
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    • pp.61-71
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    • 2001
  • In these days, surveying instruments are developing rapidly and the precision is improving continuously. The reappearance of three dimensional terrains of a great precision are possible and the calculation of the area or the volume has a high precision due to the development of the technique of the spatial information system using computer. But actually, in construction site they calculate two-dimensional area using the traditional method, plane table surveying, planimeter, and then get ground surface area through timing the slope correction factor. In this study, I show the defect and inefficiency of the calculation of the area by the traditional methods and survey the area with Electronic Distance Measuring equipment and GPS instrument. With these data, we made the three dimensional terrain model and calculated two-dimensional area and ground surface area. After that, I compared areas that calculated by algorithm method of irregular triangle and analysis of grid method with standardizing the area that calculated by the traditional method. Finally, I suggested more effective and precise method in calculating ground surface area.

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A Roentgenographic Study on the Extraction Index in Korean Adolescent (발치지수(Extraction Index) 기준에 관한 두부 방사선학적 연구)

  • Shin, Soo-Jung;Chang, Young-Il
    • The korean journal of orthodontics
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    • v.26 no.4
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    • pp.349-358
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    • 1996
  • To extract or not to extract permanent teeth for the correction of malocclusion has been a great debate in the history of orthodontics, and there is a variety of analytic methods and criteria to aid in the diagnosis. Extraction formulas that has been presented are many analytic methods that depend on arch length discrepancy, dental prominence, and skeletal pattern of the each patients. Of these analysis, the most important diagnostic factor is patient's skeletal pattern. Because the behavior of the dentition is closely dependent upon the skeletal pattern of each patient, dentition must be arranged within that person's skeletal frame. EI(Extraction Index) is composed of CF, interincisal angle, and lip position. CF is made of ODI and APDI that differentiate vertical and horizontal component of the skeletal pattern. So, EI not only represents patient's skeletal pattern, but also takes facial appearance into consideration. This study was undertaken to investigate EI and related cephalometric variables on the cephalogram of Korean adolescents which consisted of 153 persons with normal occlusion, harmonious skeleton and pleasing face. The following conclusions were obtained. 1. The mean value of the ODI is 73.5, APDI 82.5, CF 156.3 2. The mean value of the interincisal angle is 123.6 3. The mean distance of upper lip to E-line is 0.0mm, lower lip to E-line is 1.4mm. 4. The mean value of the EI is 153.8.

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