• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.7-15
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• 2010

The walkway level of service (LOS) is conceptualized using pedestrian flow rate, speed, and density according to the Korean Highway Capacity Manual (KHCM). However, as it is based on the data of commuters at peak hours, it needs to be reevaluated considering various trip purposes and a pleasant pedestrian environment. Thus, the authors aimed to investigate and analyze the characteristics of each group: pedestrians during the peak hour and those during the non-peak hour. Then they were verified statistically for the walkway evaluation criteria. In this study, the authors investigated pedestrian speed and flow in a complex transit center walkway with diverse trip purposes by peak and non-peak hour. Then the authors statistically verified the differences between the groups. A model was built for estimating pedestrian density by speed and flow; it was used to calculate the walkway capacity (67.3p/m/m) corresponding to LOS E. The authors established new criteria for LOS, applying the LOS from the HCM. These standards can then be used as the design standards for pedestrian walkways.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.357-362
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• 2021

UWB(ultra wide band) communication systems employ short pulses to transmit information which spreads the signal energy over a very wide frequency spectrum. Received signal-to-noise power ratio of UWB signals is an important factor in determining the accuracy of a positioning system. As the signal to noise power ratio gets higher, positioning errors decrease since noise becomes less effective. Calculation of signal to noise power ratio as a function of communication distance provides important guidelines for the system design. And the performance of a positioning system also depends heavily on the channel model. As a result of the analysis, it was found that the performance of the received signal to noise power ratio according to the communication distance was better in the LOS channel environment than in the Non LOS(line of sight) channel environment. And as the symbol interval of the preamble signal increases at a specific communication distance, the channel capacity of the UWB system increases.

• Safety and Health at Work
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• v.15 no.1
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• pp.59-65
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• 2024

Background: Different job strain formulations based on the Job Demand-Control model have been developed. This study evaluated longitudinal associations between job strain and psychological distress and whether associations were influenced by six formulations of job strain, including quadrant (original and simplified), subtraction, quotient, logarithm quotient, and quartile based on quotient, in randomly selected Japanese workers. Methods: Data were from waves I and II of the Survey of Midlife in Japan (MIDJA), with a 4-year followup period. The study sample consisted of 412 participants working at baseline and had complete data on variables of interest. Associations between job strain at baseline and psychological distress at follow-up were assessed via multivariable linear regression, and results were expressed as β coefficients and 95% confidence intervals including R² and Akaike information criterion (AIC) evaluation. Results: Crude models revealed that job strain formulations explained 6.93-10.30% of variance. The AIC ranged from 1475.87 to 1489.12. After accounting for sociodemographic and behavioral factors and psychological distress at baseline, fully-adjusted models indicated significant associations between all job strain formulations at baseline and psychological distress at follow-up: original quadrant (β: 1.16, 95% CI: 0.12, 2.21), simplified quadrant (β: 1.01, 95% CI: 0.18, 1.85), subtraction (β: 0.39, 95% CI: 0.09, 0.70), quotient (β: 0.37, 95% CI: 0.08, 0.67), logarithm quotient (β: 0.42, 95% CI: 0.12, 0.72), and quartile based on quotient (β: 1.22, 95% CI: 0.36, 2.08). Conclusion: Six job strain formulations showed robust predictive power regarding psychological distress over 4 years among Japanese workers.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.95-104
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• 2019

The Standard ASCE 61-14 proposes the Substitute Structure Method (SSM) as a Nonlinear Static Procedure (NSP) to estimate nonlinear displacement demands at the center of mass of piers or wharves under seismic actions. To account for bidirectional earthquake excitation according to the Standard, results from independent pushover analyses in each orthogonal direction should be combined using either a 100/30 directional approach or a procedure referred to as the Dynamic Magnification Factor, DMF. The main purpose of this paper is to present an evaluation of these NSPs in relation to four wharf model structures on soil conditions ranging from soft to medium dense clay. Results from nonlinear static analyses were compared against benchmark values of relevant Engineering Design Parameters, EDPs. The latter are defined as the geometric mean demands that are obtained from nonlinear dynamic analyses using a set of 30 two-component ground motion records. It was found that SSM provides close estimates of the benchmark displacement demands at the center of mass of the wharf structures. Furthermore, for the most critical pile connection at a landside corner of the wharf the 100/30 and DMF approaches produced displacement, curvature, and force demands that were reasonably comparable to corresponding benchmark values.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1385-1395
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• 2008

The introduction of KTX(Korea Train Express) has brought an historic change to the overall transit system in Korea. Especially, the high-speed railway stations are expanding the scope as public transit centers. However, we cannot deny that the evaluation on the high-speed railway stations had not been performed successfully so far. The evaluation covers from the connectivity of the scope from door to the stations and the transfer service in the interior of stations. We developed the service evaluation indicators of transfer facilities in the high-speed railway stations. The indicators consist of level of service(LOS), the propriety of allocation, and the quality of information throughout the facilities in the centers. We examined the 7 stations in Korea and standardized the methodology of the evaluation process by applying the indicators. Also, the evaluation is performed easy for anyone to follow.

• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.169-178
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• 2008

Level of Service (LOS) is one of ways to evaluate operational conditions. It is very important factor in evaluation especially for the facility of highways. However, some studies proved that ${\upsilon}/c$ ratio and accident rate is appeared like a second function which has a U-form. It means there is a gap between LOS and safety of highway facilities. Therefore, this study presents a method for evaluation of a signalized intersection which is considered both smooth traffic operation (delay) and traffic safety (accident). Firstly, as a result of our research, accident rates and EPDO are decreased when it has a big delay. In that reason, it is necessary to make a new Level of Service included traffic safety. Secondly, this study has developed a negative binominal regression model which is based on the relation between accident patterns and stream. Thirdly, standards of LOS are presented which is originated from calculation between annual delay costs and annual accident cost at each intersection. Lastly, worksheet form is presented as an expression to an estimation step of a signalized intersection with traffic accident prediction model and new LOS.

• Proceedings of the KOR-KST Conference
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• 1996.02a
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• pp.59-86
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• 1996

Current methods for evaluating unsignalized intersections, and estimating level-of-service (LOS) is determined from efficiency-based criteria such as little or no delay to very long delays. At present, similar procedures to evaluate intersections using safety-based criteria do not exist. The improvement of sight distances at intersections is the most effective way of improving intersection safety. However, a set of procedures is necessary to account for the limitations in current methodology. Such an approach would build upon such methods, but also account for: deficiencies in the current deterministic solution for the determination of intersection sight distances; opportunity for an accident and severity of an accident; and cost-effectiveness of attaining various levels of sight distances. In this research, a model that estimates the degree of safety at two-way stop-controlled intersections is described. Only crossing maneuvers are considered in this study because accidents caused by the crossing maneuvers are the dominate type among intersection accidents. Monte Carlo methods are used to estimate the hazard at an intersection as a function of roadway features and traffic conditions. Driver`s minimum gap acceptance in the crossing vehicles and headway distribution on the major road are used in the crossing vehicles and headway distribution on the major road are used in the model to simulate the real intersectional maneuvers. Other random variables addressed in the model are: traffic speeds; preception-reaction times of both drivers in the crossing vehicles and drivers in oncoming vehicles on the major road; and vehicles on the major roads. The developed model produces the total number of conflicts per year per vehicle and total potential kinetic energy per year per vehicle dissipated during conflicts as measurements of safety at intersections. Based on the results from the developed simulation model, desirable sight distances for various speeds were determined as 350 feet, 450 feet and 550 feet for 40 mph, 50 mph and 60 mph prevailing speed on the major road, respectively. These values are seven to eight percent less than those values recommended by AASHTO. A safety based level-of-service (LOS) is also developed using the results of the simulation model. When the total number of conflicts per vehicle is less than 0.05 at an intersection, the LOS of the intersection is `A' and when the total number of conflicts per vehicle is larger than 0.25 at an intersection, the LOS is `F'. Similarly, when the total hazard per vehicle is less than 350, 000 1b-ft2/sec2, the LOS is `F'. Once evaluation of the current safety at the intersection is complete, a sensitivity analysis can be done by changing one or more input parameters. This will estimate the benefit in terms of time and budget of hazard reduction based upon improving geometric and traffic characteristics at the intersection. This method will also enable traffic engineers in local governments to generate a priority list of intersection improvement projects.

• Journal of Korean Society of Transportation
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• v.34 no.3
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• pp.263-277
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• 2016

Traffic safety in freeway work zones is of keen interest since both crash frequency and severity are much higher than those in general freeway sections. The lane closure in work zones results in greater work load of drivers due to compulsory lane changes and speed reduction. Therefore, traffic merging control is an effective countermeasure for enhancing work zone safety. This study proposed an integrated framework based on driving and traffic simulations to evaluate traffic merging control methods in terms of traffic safety. In addition to the conventional merging method using the taper, joint merge and chicane-type merge were evaluated by the proposed methodology. Chicane-type merge outperformed other methods under level of service (LOS) A and B. On the other hand, it was identified that joint merge showed the best safety performance under LOS C traffic conditions.

• Journal of Korean Academy of Nursing Administration
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• v.8 no.2
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• pp.295-308
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• 2002

Purpose: The purpose of this quasi-experimental research is to develop the CP for primary THR patients and verify its effectiveness. Method: The CP is designed for both patients and medical employees to meet the 14-day-long hospitalization with an expert and clinical validity test, and the standardized orders are also created. 21 eligible subjects for the control group(with common care plan) and 27 subjects for the experimental group(with CP service) were assigned. Data were collected from questionnaires to evaluate patients' satisfaction level of nursing care and CP, investigation of physical complications, inspection of LOS(length of hospital stay) and hospital charges from April 2000 to February 2001 at K-hospital in Daegu. The collected data were analyzed by using the SAS program. Results: After implementation of CP, there was a statistically significant reduction in mean length of stay. The hospital charges have no considerable difference between two groups. Frequency of physical complications is reduced considerably. The experimental group scored much higher than the control group on the satisfaction level toward nursing care. And in the analysis of CP satisfaction questionnaires, many subjects have high satisfaction in items of 'I see the treatment process and hospital life', 'I feel that I am participating in my treatment process with health care staff'. The analysis of variances which cause a prolonged LOS supports that it's necessary to strengthen an evaluation of pre-operative outpatients' condition and link the home nursing care system in discharge for more shortening of LOS. Conclusion: The above results show that CP can have a positive impact on satisfaction level of inpatients with primary THR and the hospital.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.25 no.1
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• pp.27-30
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• 2014

Objectives : The purpose of this study was to investigate the endoscopic evidence of esophagitis in laryngopharyngeal reflux disease (LPRD) patients using transnasal esophagoscopy (TNE) and to correlate these findings with treatment response. Methods : Fifty patients underwent TNE at Korea University Anam Hospital from July 2007 to Feb 2009. Participants were selected from patients that presented with various laryngeal symptoms. One experienced otolaryngologist assessed esophagitis according to the Los Angeles classification system using the TNE findings. Results : Fifteen of 50 LPR patients (30%) were found to have esophagitis (12 patients with Grade A, 3 patients with Grade B, no patients with grade C/ D esophagitis). Among the 15 patients positive for esophagitis based on the endoscopic findings, 12 (80%) showed symptom improvement after pharmacological therapy. Symptom improvement was correlated with evidence of esophagitis (p=0.002) but not with RFS (p=0.749). Conclusion : Endoscopic evaluation of esophagitis using TNE is a potentially valuable tool for predicting treatment response in LPRD patients.