• Journal of Radiation Protection and Research
• /
• v.37 no.3
• /
• pp.108-115
• /
• 2012

The Urban Areas Working Group within the EMRAS-2 ($\underline{E}$nvironmental $\underline{M}$odelling for $\underline{RA}$diation $\underline{S}$afety, Phase 2), which has been supported by the IAEA (International Atomic Energy Agency), has designed some types of accidental scenarios to test and improve the capabilities of models used for evaluation of radioactive contamination in urban areas. For the comparison of the results predicted from the different models, the absorbed doses in air were analyzed as a function of time following the accident with consideration of countermeasures to be taken. Two kinds of considerations were performed to find the dependency of the predicted results. One is the 'accidental season', i.e. summer and winter, in which an event of radioactive contamination takes place in a specified urban area. Likewise, the 'rainfall intensity' on the day of an event was also considered with the option of 1) no rain, 2) light rain, and 3) heavy rain. The results predicted using a domestic model of METRO-K have been submitted to the Urban Areas Working Group for the intercomparison with those of other models. In this study, as a part of these results using METRO-K, the countermeasures effectiveness in terms of dose reduction was analyzed and presented for the ground floor of a 24-story business building in a specified urban area. As a result, it was found that the countermeasures effectiveness is distinctly dependent on the rainfall intensity on the day of an event, and season when an event takes place. It is related to the different deposition amount of the radionuclides to the surfaces and different behavior on the surfaces following a deposition, and different effectiveness from countermeasures. In conclusion, a selection of appropriate countermeasures with consideration of various environmental conditions may be important to minimize and optimize the socio-economic costs as well as radiation-induced health detriments.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.9
• /
• pp.885-892
• /
• 2015

In this study, we simulate the railway crash accident that occurred at the Sangwangsimni station on the Seoul Metro Line #2, and we propose a solution to minimize the damage. We use LS-DYNA, which is the commercial software employed for collision analysis to perform 1-D and 3-D simulations for the recurrence of accidents. By performing 1-D simulations, we analyze the load, displacement, absorbed energy of the couplers, and acceleration of vehicles, and we evaluate the safety in accidental collisions. By performing 3-D simulations, we analyze the deformation of the car and over-ridding. We propose methods to improve the safety in collisions involving railway vehicles, and we perform collision accident simulations to determine improvements when applying a high-performance energy absorber to the front car.

• Journal of Korean Society on Water Environment
• /
• v.20 no.3
• /
• pp.256-264
• /
• 2004

Adsorption characteristics of three endocrine disruptors, amitrol, nonylphenol, and bisphenol-A, were evaluated depending on the type and service duration of activated carbon (AC). Bituminous coal-, wood-, and coconut-based coals were tested. Bituminous coal-based AC (BCAC) had the greatest sorption capacity for the three chemicals tested, followed by wood-based AC (WAC) for nonylphenol and coconut palm-based AC (CAC) for bisphenol-A. During the column test, amitrol removal efficiency increased over time, indicating that hydrophilic endocrine disruptors are biodegraded in the AC column. Removal efficiencies of hydrophobic compounds such as nonylphenol and bisphenol-A decreased over time since the main removal mechanism was adsorption. The order of the amitrol removal was: BCAC-5.9 yr, CAC-3.l yr > BCAC-2.2 yr > BCAC-virgin > CAC-virgin > WAC-virgin > WAC-3.l yr. In general, used AC had greater removals than virgin AC. The order of the bisphenol-A removal was: CAC-virgin > BCAC-2.2 yr > CAC-3.l yr > WAC-virgin > BCAC-5.9 yr > WAC-3.l yr. The order of the nonylphenol removal was: BCAC-virgin > WAC-virgin > CAC-3.1 yr, WAC-3.1yr> BCAC-2.2 yr > BCAC-5.9 yr > CAC-3.1 yr. Bituminous coal AC performed the best over time. Endocrine disruptors such as these three compounds appear to be removed effectively by activated carbon through biodegradation and adsorption. Wood and coal based among the virgin ACs and 3.1 years used wood base among the used ACs appeared the lowest carbon usage rate(CUR) for nonylphenol removal by prediction model. Virgin and used coconut base ACs except BCAC had the lowest CUR for removal Bisphenol-A. Biodegradation of nonylphenol and Bisphenol-A did not occurred during the 9,800 bed volume experiment period. BCAC had the highest biodegradation capacity of 46% for amitrol among virgin ACs and the used coal based ACs had 33-44% higher biodegradation capacity than virgin's for amitrol so biodegradation is the effective removal technology for hydrophilic material such as amitrol.

• Structural Engineering and Mechanics
• /
• v.68 no.1
• /
• pp.67-80
• /
• 2018

Recently, U-section decks have been more and more used in metro and light rail bridges as an innovative concept in bridge deck design and a successful alternative to conventional box girders because of their potential advantages. U-section may be viewed as a single vent box girder eliminating the top slab connecting the webs, with the moving vehicles travelling on the lower deck. U-section bridges thus solve many problems like limited vertical clearance underneath the bridge lowest point, besides providing built-in noise barriers. Beam theory in mechanics assumes that plane section remains plane after bending, but it was found that shearing forces produce shear deformations and the plane section does not remain plane. This phenomenon leads to distortion of the cross section. For a box or a U section, this distortion makes the central part of the slab lagging behind those parts closer to the webs and this is known as shear lag effect. A sample real-world double-track U-section metro bridge is modelled in this paper using a commercial finite element analysis program and is analysed under various loading conditions and for different geometric variations. The three-dimensional finite element analysis is used to demonstrate variations in the transverse bending moments in the deck as well as variations in the longitudinal normal stresses induced in the cross section along the U-girder's span thus capturing warping and shear lag effects which are then compared to the stresses calculated using conventional beam theory. This comparison is performed not only to locate the distortion, warping and shear lag effects typically induced in U-section bridges but also to assess the main parameters influencing them the most.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.21 no.3
• /
• pp.196-202
• /
• 2018

Purpose: Treatment of chronic constipation and fecal impaction is usually outpatient and requires high or frequent doses of laxatives. However, there are children who fail outpatient treatments, sometimes repeatedly, and are ultimately hospitalized. We sought to compare the characteristics of the children who failed outpatient treatment and needed inpatient treatment vs those who achieved success with outpatient treatment, in an effort to identify attributes that might be associated with a higher likelihood towards hospitalization. Methods: In this retrospective cohort study, we reviewed the medical records of all patients aged 0 to 21 years, with chronic functional constipation and fecal impaction seen in the pediatric gastroenterology clinic over a period of 2 years. Results: Total of 188 patients met inclusion criteria. While 69.2% were successfully treated outpatient (referred to as the outpatient group), 30.9% failed outpatient treatment and were hospitalized (referred to as the inpatient group). The characteristics of the inpatient group including age at onset of $3.6{\pm}3.6years$ (p=0.02); black ethnicity (odds ratio [OR] 4.31, 95% confidence interval [95% CI] 2.04-9.09); p<0.001); prematurity (OR 2.39, 95% CI 1.09-5.26; p=0.02]; developmental delay (OR 2.20, 95% CI 1.12-4.33; p=0.02); overflow incontinence (OR 2.26, 95% CI 1.12-4.53, p=0.02); picky eating habits (OR 2.02, 95% CI 1.00-4.08; p=0.04); number of ROME III criteria met: median 4, interquartile range 3-5 (p=0.04) and $13{\pm}13.7$ constipation related prior encounters (p=0.001), were significantly different from the outpatient group. Conclusion: Identification of these characteristics may be helpful in anticipating challenges and potential barriers to effective outpatient treatment.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.11
• /
• pp.1113-1120
• /
• 2012

This paper deals with the analysis of interior noise and low frequency noise characteristic for the Busan citizens to use public transport, Busan Metro Line 3. The interior noise evaluation index, articulation index(AI) is evaluated the lower value about average 22 % in a whole range, this is difficult to have a conversation. Also, noise criteria(NC) curve is partially evaluated as NC-65 below 2000 Hz, space type is evaluated as factories. Another of interior noise evaluation index, preferred speech interference level(PSIL) is evaluated the upper value about average 66 dB(A) in a whole range, this is evaluated to be interrupted. In the case of low frequency noise(20~200 Hz), the measurement of low frequency noise is assessed largely beyond noise criteria of ISO 226. The low frequency noise should be reduced because low frequency noise affects on psychological stress and displeasure although low frequency noise is not recognized by auditory sense. The low frequency noise criteria and guideline will be enacted from now on in Korea.

• International Journal of Safety
• /
• v.7 no.1
• /
• pp.39-43
• /
• 2008

With ever increasing number of citizen using subway stations everyday, safety, health and comfort of passengers and occupants (mostly metro personnel) have become important social issues. Considering the fact that various physical variables and pollutants such as particulate, VOCs and biological agents are closely related to indoor air quality (IAQ) which may cause health problems, a method of quantitative assessment using information-theoretic measure on such variables needs to be devised and implemented for comfort, health and safety of passengers and occupants in the subway station. A basic framework for assessing indoor air quality (for comfort and health) and safety in subway station is suggested. In particular, application of information-theoretic measure for the assessment of indoor air quality, comfort and safety in subway station is discussed. Some examples are presented as well.

• Journal of the Korean Society of Safety
• /
• v.26 no.6
• /
• pp.111-117
• /
• 2011

Risk-based railway safety management has been mandatory in Korea as by relevant laws and regulations enacted since the Railway Safety Act 2004. In particular, the Railway Vehicle Safety Guidance came into effect on Jan 1, 2008 specifies the details of methodology for hazard analysis, risk assessment and safety verification and validation. Fundamentals for success of the risk-based safety management are systematic hazard identification and risk assessment by use of reasonable risk assessment criteria, but the principle of risk-based safety management has not been applied in an effective way to introduction and maintenance of railway vehicle systems because definite risk assessment criteria have not been set down for each railway system or railway network. The purpose of this study is to suggest a risk matrix development principle for risk assessment of domestic urban metro vehicles by analyses of relevant rules and railway operating environment of Korea.

• International Journal of Internet, Broadcasting and Communication
• /
• v.10 no.3
• /
• pp.51-58
• /
• 2018

In order to utilize various data provided by Korea public open data portal, data should be systematically managed using a database. Since the range of open data is enormous, and the amount of data continues to increase, it is preferable to use a database capable of processing big data in order to analyze and utilize the data. This paper proposes data modeling and implementation method suitable for public data. The target data is subway related data provided by the public open data portal. Schema of the public data related to Seoul metro stations are analyzed and problems of the schema are presented. To solve these problems, this paper proposes a method to normalize and structure the subway data and model it in NoSQL database. In addition, the implementation result is shown by using MongDB which is a document-based database capable of processing big data.

• Journal of Digital Convergence
• /
• v.18 no.10
• /
• pp.437-442
• /
• 2020

Information boards installed in Seoul subway stations are currently in four languages: Korean, English, Chinese, and Japanese. Informational announcements are provided to inform the main information or operation information through the LCD monitor installed in the train and in Korean. However, users are confused because the subway guide board screen displays advertisements more heavily than driving information As a research method, we grasped the current status and problems of the subway guide board installed on the Seoul subway, and presented an improved new subway guide board drafts. An online survey was conducted on 67 people, ranging from teens to 60s who mainly use the Seoul Metro. As a result of the study, the screen design is different for each boarding route, so it is necessary to unify the subway guide board that provides only necessary information. In particular, since the user transfers the subway several times in order to move from place to place, the subway guide board design should function as an emergency disaster guide or boarding information, not an advertising signboard.