• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.1-7
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• 2012

Systematic safety research by Korea Government has been made to enhance the safety of CNG (compressed natural gas) vehicles since the burst of compressed cylinder of an urban bus in August 9, 2010. This article summarizes some major activities to ensure the safety of CNG vehicles, which covers review of regulation, safety management system including standard of inspection and certification, and training program of inspectors and car mechanics. Specifically, the followings were reviewed; type of CNG cylinder, location of CNG cylinder, material and type of fuel line and vent line, modification of pipeline connection, installation of gas detector, installation of emergency shutdown valve, installation of protecting cover for cylinder, obligations for CNG vehicle filling station. improving periodical inspection, routine test on gas vehicles, training program for engaged in gas vehicles, and designation of safety manager for CNG bus company. This paper suggests how to improve safety of CNG vehicles as a result of review of above mentioned check items.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.555-563
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• 2016

Line capacity of railways is a core criterion to decide maximum trips in accordance with traffic demand and a priority in railway investment to improve transportation capability. Particularly, because two operators will start revenue services in the HSR from mid-2016, the line capacity should be carefully calculated and controlled to avoid conflicts between the maximum number of KTXs, and the number needed to guarantee the effective competition of the operators. Meanwhile, there have been many arguments about calculating the line capacity, because this number is affected by the number of trips by train types, stopping pattern and dwell time in each station, journey time, crossing or passing, safety headway between trains, etc. To deal successfully with these kinds of problems, this study proposes a simulation method to calculate the line capacity that considers train operation according to the operator's service policies.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.725-744
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• 2022

As the construction of infrastructure using the underground tunnel in urban area have been rapidly increased, various accidents and collapses of tunnel including structure have been occurred in deep urban tunnelling. The concern and worry relating to the risk and safety of the tunnel during excavation is becoming the key issues in deep urban tunnelling. In this study, it was conducted for deep urban tunnel at GTX (Great Train Express) line which was located in Seoul metropolitan area to determine the risk characteristics for tunnel according to urban tunnelling. Also, it was reviewed the risk analysis and evaluation of the tunnel, shaft and station. And after a review of risk analysis and evaluation for risk register and hazard identification by using a risk matrix method, safety management of the tunnel according to excavation was evaluated to be secured. This study is expected to be applied as useful approach in deep urban tunnelling if you need to review the risk and safety management system of tunnel according to mitigation measures in complex urban tunnelling.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.51-60
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• 2018

This study would like to know the relationship among interpersonal competency based self-understanding and acceptance of others, self leadership, stress-coping and military adjustment. For this, 1289 military trainee in the army training station were surveyed. In results, The first, the acceptance of others did not have a significant effect on the perform-will, but had a significant effect on the job satisfaction and self leadership. The self-understanding had a significant effect on perform-will, job satisfaction and self leadership. The second, self leadership mediated between interpersonal competency and military adjustment. The third, in case of the perform-will, the moderating effect was showed in self leadership when the stress coping level was high. But in case of the job satisfaction, it was showed in both high group and low. Implications of this study is that the interpersonal competency based self-understanding and acceptance of others, self leadership and stress coping can be the positive potential variables on the military adjustment.

• Progress in Medical Physics
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• v.30 no.1
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• pp.1-6
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• 2019

Purpose: This study conducts a comparative evaluation of the skin dose in CyberKnife (CK) and Helical Tomotherapy (HT) to predict the accurate dose of radiation and minimize skin burns in head-and-neck stereotactic body radiotherapy. Materials and Methods: Arbitrarily-defined planning target volume (PTV) close to the skin was drawn on the planning computed tomography acquired from a head-and-neck phantom with 19 optically stimulated luminescent dosimeters (OSLDs) attached to the surface (3 OSLDs were positioned at the skin close to PTV and 16 OSLDs were near sideburns and forehead, away from PTV). The calculation doses were obtained from the MultiPlan 5.1.2 treatment planning system using raytracing (RT), finite size pencil beam (FSPB), and Monte Carlo (MC) algorithms for CK. For HT, the skin dose was estimated via convolution superposition (CS) algorithm from the Tomotherapy planning station 5.0.2.5. The prescribed dose was 8 Gy for 95% coverage of the PTV. Results and Conclusions: The mean differences between calculation and measurement values were $-1.2{\pm}3.1%$, $2.5{\pm}7.9%$, $-2.8{\pm}3.8%$, $-6.6{\pm}8.8%$, and $-1.4{\pm}1.8%$ in CS, RT, RT with contour correction (CC), FSPB, and MC, respectively. FSPB showed a dose error comparable to RT. CS and RT with CC led to a small error as compared to FSPB and RT. Considering OSLDs close to PTV, MC minimized the uncertainty of skin dose as compared to other algorithms.

• Journal of Convergence for Information Technology
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• v.9 no.6
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• pp.65-74
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• 2019

The purpose of this study is to reveal the causal relationship between core categories experienced by firefighters in the organization based on the grounded theory as a method of qualitative research. In this study, we interviewed 50 firefighter information providers who work in Seoul in 2014, 2017, and 2018, and conducted a research model that shows the causal relationship of core categories through open coding, axial coding, and selective coding. As a result, compassion experienced by information providers is revealed as a core category, and this compassion has a positive effect on positive work related identity, collective self esteem, and job performance. Therefore, the theoretical implication of this study is that it has derived a research model that shows the causal relationship between compassion and job performance based on grounded theory as a qualitative research methodology. This study will contribute to the formation of the organizational culture that enables firefighters who desperately need compassion in the fire department organization to more actively exchange compassionate actions.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.427-436
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• 2018

HADAX is a serial communication converter of train control computer. It is connected with various signal equipments such as wayside signal equipments, station signal equipments, train control computers, and transmits control information and signal condition information for train control. And transmits information to several electronic interlocking devices through a splitter interface. Since HADAX interfaces with many signaling devices through serial communication, frequent communication connection faults necessitate improvement of performance such as dual system configuration, integration of external splitter, and multi-channelization of communication card. The improved HADAX device should have compatibility with the dimensions of existing enclosure and enclosure, and verify the performance of dual system and splitter integration. Therefore, we verified the performance of HADAX through the route control test, dual system test, and multi-channel communication test with splitter integrated connection by connecting with the existing signal equipment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.1-14
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• 2021

It is highly challenging to measure the efficiency of electric vehicle charging stations (EVCSs) because factors affecting operational characteristics of EVCSs are time-varying in practice. For the efficiency measurement, environmental factors around the EVCSs can be considered because such factors affect charging behaviors of electric vehicle drivers, resulting in variations of accessibility and attractiveness for the EVCSs. Considering dynamics of the factors, this paper examines the technical efficiency of 622 electric vehicle charging stations in Seoul using data envelopment analysis (DEA). The DEA is formulated as a multi-period output-oriented constant return to scale model. Five inputs including floating population, number of nearby EVCSs, average distance of nearby EVCSs, traffic volume and traffic congestion are considered and the charging frequency of EVCSs is used as the output. The result of efficiency measurement shows that not many EVCSs has most of charging demand at certain periods of time, while the others are facing with anemic charging demand. Tobit regression analyses show that the traffic congestion negatively affects the efficiency of EVCSs, while the traffic volume and the number of nearby EVCSs are positive factors improving the efficiency around EVCSs. We draw some notable characteristics of efficient EVCSs by comparing means of the inputs related to the groups classified by K-means clustering algorithm. This analysis presents that efficient EVCSs can be generally characterized with the high number of nearby EVCSs and low level of the traffic congestion.

• Health Policy and Management
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• v.31 no.2
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• pp.158-172
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• 2021

Background: Metabolic syndrome has been known as a risk of cardiovascular disease. Meanwhile, high sensitivity C-reactive protein (hs-CRP) is used as a predictor of cardiovascular disease. In this paper, we aimed to investigate the association between hs-CRP and metabolic syndrome. Method: A total of 7,633 were chosen as the study population from the 7th Korea National Health and Nutrition Examination Survey dataset (2016-2017). Our dependent variable was whether an individual had metabolic syndrome or not, and the independent variable of interest was hs-CRP which was categorized into three groups. The chi-square tests and hierarchical logistic regression analyses reflecting survey characteristics were conducted. All analyses were stratified by gender. Results: According to the adjusted model with all covariates, compared to individuals having the low risk of hs-CRP, those having its average risk were more likely to have metabolic syndrome in men (odds ratio [OR], 1.41; 95% confidence interval [CI], 1.12-1.76) and women (OR, 1.69; 95% CI, 1.33-2.16). Individuals having the high risk was not significantly different in men; however, they were more likely to have metabolic syndrome in women (OR, 2.03; 95% CI, 1.28-3.23). Conclusion: In an upcoming aging society, it is important to reduce the risk of metabolic syndrome to improve population health. This study suggests that hs-CRP may be used as a marker of the risk of metabolic syndrome in a gender-specific way, thereby contributing to enhancing awareness of the risk of metabolic syndrome among the general public.

• Atmosphere
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• v.32 no.3
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• pp.179-189
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• 2022

The purpose of this study is to build and evaluate a high-resolution (50 m) KMAPP (Korea Meteorological Administration Post Processing) reflecting building data. KMAPP uses LDAPS (Local Data Assimilation and Prediction System) data to detail ground wind speed through surface roughness and elevation corrections. During the detailing process, we improved the vegetation roughness data to reflect the impact of city buildings. AWS (Automatic Weather Station) data from a total of 48 locations in the metropolitan area including Seoul in 2019 were used as the observation data used for verification. Sensitivity analysis was conducted by dividing the experiment according to the method of improving the vegetation roughness length. KMAPP has been shown to improve the tendency of LDAPS to over simulate surface wind speeds. Compared to LDAPS, Root Mean Square Error (RMSE) is improved by approximately 23% and Mean Bias Error (MBE) by about 47%. However, there is an error in the roughness length around the Han River or the coastline. Accordingly, the surface roughness length was improved in KMAPP and the building information was reflected. In the sensitivity experiment of improved KMAPP, RMSE was further improved to 6% and MBE to 3%. This study shows that high-resolution KMAPP reflecting building information can improve wind speed accuracy in urban areas.