• Journal of Korean Society of Transportation
• /
• v.29 no.2
• /
• pp.37-45
• /
• 2011

The main objective of this study is two-fold: 1) to analyze the effect of PG technology application on road user's satisfaction and driving speed, and 2) to investigate the relationship between driver's subjective workload level and their reactions related to the PG technology application. Based on the result of field observation, the experimental scenario for driving simulation study was prepared. The experimental results showed that drivers were more satisfied to the road condition with PG technology applied, and even the pattern of speed reduction was more stable than control condition. The pattern of speed reduction along driver's subjective driving workload level were slightly different by physical road condition, and road user's satisfaction was revealed to be negatively correlated with their subjective driving workload level. This result indicates that depending on situation and driver characteristic, information for the drivers could be nothing more than nuisance that just distracts drivers. In order to facilitate the implementation of PG technology in Korea, further study on related human factors, especially for those who are weak in traffic situations, is recommended.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.3B
• /
• pp.175-183
• /
• 2012

In this study, Galerkin scheme and SU/PG scheme of Petrov-Galerkin family were applied to the shallow water equations and a finite element model for shallow water flow was developed. Numerical simulations were conducted in several flumes with convection-dominated flow condition. Flow simulation of channel with slender structure in the water course revealed that Galerkin and SU/PG schemes showed similar results under very low Fr number and Re number condition. However, when the Fr number increased up to 1.58, Galerkin scheme did not converge while SU/PG scheme produced stable solutions after 5 iterations by Newton-Raphson method. For the transcritical flow simulation in diverging channel, the present model predicted the hydraulic jump accurately in terms of the jump location, the depth slope, and the flow depth after jump, and the numerical results showed good agreements with the hydraulic experiments carried out by Khalifa(1980). In the oblique hydraulic jump simulation, in which convection-dominated supercritical flow (Fr=2.74) evolves, Galerkin scheme blew up just after the first iteration of the initial time step. However, SU/PG scheme captured the boundary of oblique hydraulic jump accurately without numerical oscillation. The maximum errors quantified with exact solutions were less than 0.2% in water depth and velocity calculations, and thereby SU/PG scheme predicted the oblique hydraulic jump phenomena more accurately compared with the previous studies (Levin et al., 2006; Ricchiuto et al., 2007).

• International Journal of Highway Engineering
• /
• v.13 no.1
• /
• pp.59-67
• /
• 2011

It can prevent traffic accidents in a way as taking precautionary measures for road safety at signalized intersection in advance. Particularly, traffic accidents can be reduced at relatively low cost without redesigning alignments. That is 'Positive Guidance method' which can help prevent traffic accidents through improvement of road facilities at signalized intersection. In this study, potentially higher hazardous signalized intersection due to speeding was selected through site investigation. Field analysis at designated section was conducted and devised a plan for improvements of road facilities. Subjects drove in driving simulator in 3-D virtual reality of designated intersection. Based on data from simulator, statistical analysis(t-verification) was conducted for 'Before and After effectiveness' of speed reduction. As a result, it indicates that speed reduction was effective after improvements at each spot in driving simulator. In the future, hazardous signalized intersections which can be applied for PG method will be effective for road safety based on this research.

• Economic and Environmental Geology
• /
• v.36 no.3
• /
• pp.201-212
• /
• 2003

Recently, the ability of earthquake detection in the Kyungsang Basin of southeastern Korean Peninsula is greatly improved since seismic stations including seismic network of KIGAM(Korea Institute of Geoscience and Mineral Resources) have been significantly increased. However, a large number of signals from explosions are recorded because of frequent medium to large chemical explosions. The discrimination between natural earthquakes and explosions in the Basin has become an important issue. High frequency local records from 43 earthquakes and 43 explosions with comparable magnitude are selected to establish a reliable discrimination technique in the Basin. Several discrimination techniques in spectral domain using spectral amplitude ratios among Pg, Sg, and Lg waves are widely examined with tile selected data. Among them the Pg/Lg spectral ratio method is appeared to be a good discrimination technique to improve the discrimination power. Multivariate discriminant analysis is also applied to the Pg/Lg spectral ratios. The discrimination power of the Pg/Lg ratios for distance corrected three component record compared to uncorrected vertical component one shows distinct improvement. In the frequency band 4 to 14 Hz, Pg/Lg spectral ratio for distance corrected three component record provides discrimination power with a total misclassification probability of only 0.89%.

• Proceedings of the Korea Contents Association Conference
• /
• 2005.11a
• /
• pp.601-607
• /
• 2005

In this paper, we aggregate multi-links information between boundary nodes using the line segment scheme that aggregates topology information within PG referring bandwidth and delay parameter. To do this, we propose a modified line segment algorithm using two line segment method that represents two points which consist of delay-bandwidth pair to reduce topology information and provide a flexibility to the multiple-links aggregation. And we apply it to current star topology aggregation. Through the simulation result analysis, the proposed star topology aggregation scheme presents the better performance than existing scheme.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.18 no.2
• /
• pp.103-111
• /
• 2005

In this paper, a new meshfree technique which improves the numerical integration accuracy is introduced. This new method called thc Petrov-Galerkin natural clement method(PG-NEM) by authors is based on the Voronoi diagram and the Delaunay triangulation which is based on the same concept used lot conventional natural clement method called the Bubnov-Galerkin natural element method(BG-NEM). But, unlike the BG-NEM, the test basis function is differently chosen, based on the concept of Petrov-Galerkin, such that its support coincides exactly with a regular integration region in background mesh. Therefore, it is expected that the proposed technique ensures the remarkably improved numerical integration accuracy in comparison with the BG-NEM.

• Journal of the East Asian Society of Dietary Life
• /
• v.11 no.1
• /
• pp.26-32
• /
• 2001

독소원성 대장균(enterotoxigenic Escherichia coli, ETEC, EC81, serotype O148:H28)이 생산하는 heat labile enterotoxin(LT)를 검색해 본 결과, reversed passive latex agglutination(RPLA)법에 있어서는 2배로 희석한 용액 (50 ng)으로부터 64로 희석한 용액 (1.56 ng)에서까지 양성반응을 보였으며 polymerase chain reaction (PCR)기법에 있어서는 10 ng으로부터 1 pg희석용액에서까지 147-base pair(bp)의 LT DNA fragment가 확인되었다. Clostridium perfringens A형 (NCTC8238, Hobbs serotype 2)이 생산한는 장독소를 검색해 본 결과, RPLA법에 있어서는 2배로 희석한 용액 (50 ng)으로부터 64로 희석한 용액 (1.56 ng)에서 까지 양성반응을 보여 독소원성대장균이 생산하는 LT와 일치하였으나, PCR기법에 있어서는 10ng로부터 10 pg 희석용액에서 까지 354-bp의 DNA fragment가 확인되어 독소원성대장균이 생산하는 LT보다 1/10의 낮은 감도를 보였다. PCR기법은 RPLA법에 비하여 훨씬 신속하고 소량의 sample로 장독소를 확인할 수 있었다.

• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.198-198
• /
• 2011

The numerical simulation of dam break problem suffers from several challenges in terms of accuracy, stability, and versatility of the simulation algorithm since the water flow is generally discontinuous and presents abrupt variations. Thus, to obtain stable and accurate solutions, flow models for this purpose require numerical schemes provided with shock-capturing properties, and with the ability to work with flexible two-dimensional meshes. In this context, SU/PG method(Hughes and Brooks, 1979) is excellent candidate for the solution of the dam break problem. The weak formulation of the equations and the discontinuous polynomial basis lead to an accurate representation of bore waves(shocks). Furthermore, the discretization of the domain in finite elements is extremely effective in modeling complex geometries. In this study, a finite element model based on the SU/PG scheme is developed to solve shallow water equations and the model is applied to dam break problem. It is found that the present model accurately captures the bore wave that propagates downstream while spreading laterally and the depression wave that moves upstream. Furthermore, the propagation and formation of water surface profile compared favorably with those obtained by the previously published results.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2003.05a
• /
• pp.485-488
• /
• 2003

• Korean journal of applied entomology
• /
• v.37 no.1
• /
• pp.31-37
• /
• 1998

Random amplified polymorphic DNA (RAPD) markers were used to analyze genetic similarity among 8 clones of apierous green peach aphid, two types (M. persicae Sulzer and M. nicotianae lack man) classified by their mo~hologi~cahla raters and host preference (Blackman, 1987), collected from tobacco plants. The genetic variation among these clones was evaluated by polymerase chain reaction amplification with 20 random primers. The higher GC contents of primers, the better in amplification efficiency of PCR reaction in general. The genetic similarities among eight aphid clones were analyzed from UPGMA (unweighted pair group average method) cluster analysis based on simple matching coefficient. The range of genetic similarity coefficients was 0.414 to 0.808. The most close relationship among the clones was similarity coefficient of 0.808 between the PG2 and the PG3 clone. The eight aphid clones analyzed were clustered into three groups by the genetic similarity coefficient. The first group, PG1, PG2, PG3 clone including in M. persicae type by their morphological characters and RED clone in M. nicotianae type was clustered at the genetic similarity coefficient of 0.643. The second group, GR1, GR2, BRN in M. nicotianae type was at the 0.636;and the third group was DBR clone in M. persicae type. The results did not indicate any correlation between m&-phological types (M. persicae and M. nicotianae) and RAPD polymorphism. We could not detect any obvious genetic relationships of the two morphological types of the green peach aphid collected from tobacco plants.