• Safety and Health at Work
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• v.1 no.1
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• pp.98-101
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• 2010

This study explored the health hazard of those exposed to methylene chloride by assessing its atmospheric concentration when a tear gas mixture was aerially dispersed. The concentration of methylene chloride ranged from 311.1-980.3 ppm (geometric mean, 555.8 ppm), 30 seconds after the dispersion started. However, the concentration fell rapidly to below 10 ppm after dispersion was completed. The concentration during the dispersion did not surpass the National Institute for Occupational Safety and Health 'immediately dangerous to life or health' value of 2,300 ppm, but did exceed the American Conference of Governmental Industrial Hygienists excursion limit of 250 ppm. Since methylene chloride is highly volatile (vapor pressure, 349 mmHg at $20^{\circ}C$), the post-dispersion atmospheric concentration can rise instantaneously. Moreover, the o-chlorobenzylidenemalononitrile formulation of tear gas (CS gas) is an acute upper respiratory tract irritant. Therefore, tear gas mixtures should be handled with delicate care.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.285-292
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• 2020

This paper introduces a new computational efficient Dilution of Precision (DOP)-based landmark exclusion method while ensuring the safety of the LiDAR-based navigation system that uses an innovation-based Nearest-Neighbor (NN) Data Association (DA) process. The NN DA process finds a correct landmark association hypothesis among all potential landmark permutations using Kalman filter innovation vectors. This makes the computational load increases exponentially as the number of landmarks increases. In this paper, we thus exclude landmarks by introducing DOP that quantifies the geometric distribution of landmarks as a way to minimize the loss of integrity performance that can occur by reducing landmarks. The number of landmarks to be excluded is set as the maximum number that can satisfy the integrity risk requirement. For the verification of the method, we developed a simulator that can analyze integrity risk according to the landmark number and its geometric distribution. Based on the simulation, we analyzed the relationship between DOP and integrity risk of the DA process by excluding each landmark. The results showed a tendency to minimize the loss of integrity performance when excluding landmarks with poor DOP. The developed method opens the possibility of assuring the safety risk of the Lidar-based navigation system in real-time applications by reducing a substantial amount of computational load.

• Journal of the Korea Safety Management & Science
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• v.14 no.3
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• pp.135-141
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• 2012

This study was conducted to evaluate the characteristics of exposure to asbestos for ship repair workers in Korea by a systematic review. The number of articles studying asbestos exposure levels from ship repair workplaces was found to be 4. All asbestos concentration reported as either geometric mean and geometric standard deviation or ranges were transformed to arithmetic mean to estimate exposure level. In addition, weighted arithmetic means(WAMs) were calculated by weighing of the different number of samples. The WAM concentrations were 2.746 f/cc during asbestos dismantling work, 0.034 f/cc before asbestos dismantling work and 0.065 f/cc after working respectively. The maximum airborne concentration of asbestos during asbestos removal work was 7.02 f/cc which was 70 times higher than the occupational exposure limit of Korea, 0.1 f/cc. This study recommends that retrospective exposure to asbestos based on various ship types and operations should be assessed.

• Geotechnical Engineering
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• v.6 no.2
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• pp.47-54
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• 1990

The accuracy of a limit equilibrium analysis of slope stability depends on the accuracy with which the strength properties and geometric conditions can be defined, and on the inherent accuracy of the method of analysis. Most of the slope stability analysis method have been computer coded, and this is a comparative study on the accuracy of these programs. Comparative analyses have shown that for the slopes with relatively simple conditions Host of the programs which are widely used in this country result in the same value of safety factor with an accuracy no worse than $\pm$5%. Similar results can be obtained from the examination of the several slope failure for which accurate information is available on the strength and geometric conditions of the earth slope. The critical failure surface, however, can be different from the actual slip surface, although nearly the same factors of safety are obtained from the analyses of each surface.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.4
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• pp.169-176
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• 2001

This study aims to present a more reasonable control value than the exiting one by comparing and analyzing control values and field instrument8tion values of the whole excavation depth of the four case sites, using geometric averaging as a statistical method. The range of the study is confined to the horizontal displacement of braced excavation walls among a variety of items, prescribed in the control values by approximately of the allowable and design values, and by safety factors. As a result, it is desirable to revise 70, 90, and 100 percent of LEVEL I, II, and III, respectively. The horizontal displacement values of the allowable and design values approximations should change to 104, 133, and 148 percent of the allowable and design values, respectively. In addition, modifying the horizontal displacement control value of the braced excavation walls is not needed. The horizontal displacement value, presented in the control value as a safety factor, is now 1.19, as it has a slight difference from the present value.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.55-60
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• 2002

In order to investigate the microbiological contamination of spring water, we performed the standard plate count, coliform and psychrotrophilic bacteria in 109 spring waters in Seoul. Of 109 spring waters, geometirc mean standard plate count was 0.19 CFU/ml, and the highest in Mt. Boolam, 4..43 CFU/ml and Mt. Dobong, 3.86 CFU/ml, but not detected in Mt. Woomyun and Mt. Cheonggye. Four spring waters have shown over 100 CFU/ml in standard plate count. The geometric mean psychrotrophilic bacteria was 49.2 CFU/ml, the most prevalent spring water was Mt. Nam, 125 CFU/ml, the lowest Mt. Woomyeun. Among a total of 109, coliform was detected from 21 spring waters(19.3%) and the geometric mean of coliform was 0.005 MPN/100ml. The isolated genera of coliform were 7 isolates of E. coli(33%), 5 Klebsiella(24%), 4 Enterobacter(19%), 3 Citrobacter(14%) and 2 Serratia(10%), respectively. The 22 spring waters(20.2%) failed to meet the standard limits of drinking water based on regulation in Korea. The inappropriate rate of standard plate count in spring water was 4.5%, that of coliform was 81.1% and both of them was 13.6%. There was the significant correlation between standard plate count and psychrotrophilic bacteria in spring water(r=0.95, p<0.01).

• Journal of Korea Multimedia Society
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• v.14 no.5
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• pp.595-606
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• 2011

This paper proposes a robust watermarking scheme for GIS digital map by using the geometric properties of polyline and polygon, which are the fundamental components in vector data structure. In the proposed scheme, we calculate the lengths and the perimeters of all polylines and polygons in a map and cluster them to a number of groups. Then we embed the binary watermark by changing the mean of lengths and perimeters in an embedding group. For improving the safety and robustness, we permute the binary watermark through PRNS(pseudo-random number sequence) processing and embed it repeatedly in a model. Experimental results verified that our scheme has a good invisibility, safety and robustness to various geometric attacks and also our scheme needs not the original map in the extracting process of watermark.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.142-154
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• 1994

In this paper, stochastic imperfection sensitivity analyses of stiffened cylindrical shells under static load are presented. Multimode formulation is performed for the buckling load calculation based on the Donnell's theory and Galerkin approximation. Random imperfection field theory and response surface method are combined with deterministic bucking analysis scheme to perform stochastic imperfection sensitivity analyses of stiffened cylindrical shells considering random geometric imperfection. From the characteristics of probabilistic bucking load, the relation between reliability index and safety parameter can be obtained in addition to the relation between load and reliability index. Those results can be used to determine the range of required safety parameter and acceptable imperfection.

• Journal of Auto-vehicle Safety Association
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• v.13 no.4
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• pp.7-13
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• 2021

This paper presents an vulnerable road user (VRU) classification and tracking algorithm using vision and LiDAR sensor fusion method for urban autonomous driving. The classification and tracking for vulnerable road users such as pedestrian, bicycle, and motorcycle are essential for autonomous driving in complex urban environments. In this paper, a real-time object image detection algorithm called Yolo and object tracking algorithm from LiDAR point cloud are fused in the high level. The proposed algorithm consists of four parts. First, the object bounding boxes on the pixel coordinate, which is obtained from YOLO, are transformed into the local coordinate of subject vehicle using the homography matrix. Second, a LiDAR point cloud is clustered based on Euclidean distance and the clusters are associated using GNN. In addition, the states of clusters including position, heading angle, velocity and acceleration information are estimated using geometric model free approach (GMFA) in real-time. Finally, the each LiDAR track is matched with a vision track using angle information of transformed vision track and assigned a classification id. The proposed fusion algorithm is evaluated via real vehicle test in the urban environment.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.151-160
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• 2009

The aim of this study is to propose economical driving speed index which those are geometric road status; assess the levels of which those cost-benefit of driving energy consumption and emission; are search road safety design and operational technology for driving simulator. For the objective, we analyzed the current status of driving energy consumption and driving scenarios by the road alignments, and reviewed driving and technical specifications by the geometric types of road according to the implementation, and extended completion. Throughout the result of this study, diverse related driving information provision service, efficiently navigation driving module is expected to be implemented in the national highway design system.