• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.576-585
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• 2017

Dynamic thermal rating (DTR) of overhead transmission lines can provide a significant increase in transmission capacity compared to the static thermal rating. However, the DTR are usually estimated by the traditional thermal model of overhead conductor that is highly dependent on the solar, wind speed and wind direction data. Consequently, the estimated DTR would be unreliable and the safety of transmission lines would be reduced when the solar and wind sensors are out of function. To address this issue, this study proposed a novel thermal model of overhead conductor based on the thermal-electric analogy theory and Markov chain. Using this thermal model, the random variation of conductor temperature can be simulated with any specific current level and ambient temperature, even if the solar and wind sensors are out of function or uninstalled. On this basis, an estimation method was proposed to determine the DTR in the form of probability. The laboratory experiments prove that the proposed method can estimate the DTR reliably without measured solar and wind data.

• Journal of Environmental Impact Assessment
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• v.15 no.6
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• pp.453-458
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• 2006

A turnout system which permits trains to pass from one track to another consists of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 180km/h, at conventional lines by the year of 2010. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefore, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, evaluation of noise characteristics around the improved turnout system was performed through the field measurements. Field measurements of noise around the conventional and the high-speed turnout system were also carried out for the comparison.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.107-110
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• 2009

A basic design for a Technical Development Model (TDM) of liquid oxygen lines from the turbopump exit to the oxidizer valves of the combustion chamber and the gas generator was conducted to develop a turbopump-fed liquid rocket engine. The TDM is composed of straight lines, elbows, bellows, a branch, an orifice, flanges and a heat insulator. Materials were determined by consideration of operation conditions, weight constraint and manufacturing procedures. The size and the location of each component were determined by flow analysis of the required flowrate and the pressure loss. Basic designs of the components were conducted by consideration of the operating temperature and the maximum expectation operating pressure. The safety factors were evaluated by structural analysis of design of each component.

• Strategy21
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• s.36
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• pp.150-179
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• 2015

This thesis analyzes Somali piracy as a non-traditional threat to the Sea Lines of Communication (SLOC) and international countermeasures to the piracy. In an era of globally interdependent economies, the protection of sea lines and freedom of navigation are prerequisites for the development of states. Since the post-Cold War began in the early 1990s, ocean piracy has emerged as a significant threat to international trade. For instance, in the Malacca Strait which carries 30 percent of the world's trade volume, losses from failed shipping, insurance, plus other subsequent damages were enormous. Until the mid-2000s, navies and coast guards from Malaysia, Indonesia, Singapore, together with the International Maritime Organization (IMO), conducted anti-piracy operations in the Strait of Malacca. The combined efforts of these three maritime states, through information sharing and with reinforced assets including warships and patrol aircrafts, have successfully made a dent to lower incidents of piracy. Likewise, the United Nations' authorization of multinational forces to operate in Somali waters has pushed interdiction efforts including patrol and escort flotilla support. This along with self-reinforced security measures has successfully helped lower piracy from 75 incidents in 2012 to 15 in 2013. As illustrated, Somali piracy is a direct security threat to the international community and the SLOC which calls for global peacekeeping as a countermeasure. Reconstructing the economy and society to support public safety and stability should be the priority solution. Emphasis should be placed on restoring public peace and jurisdiction for control of piracy as a primary countermeasure.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.755-770
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• 2006

1974. 8.15 SeoulMetro, beginning with the first electric railway established at six cities, so it is managing mass transportation of traffic. Especially, in case of seoul, It is managing that from one to eight lines, 286.9km, 265 stations have installed and now it is carrying about 5.5million of passengers everyday, and 2,000million passengers a year. So accident is increasing from the station every year. For this measure, SeoulMetro prepares safety fence for passengers crash but, as suicides or people who watch the accident took place, for at the bottom of passengers crash protection, PSD installing is needed. Even though, PSD is managing ATO section but, in controlling SeoulMetro, one to four lines sections are (ATS, ATC)section. Between as ATS, ATC section, ATO section, subway gate and PSD must have opened and crossed always at the time. And the interlock control corrosion protection gate, managing skills with installation, method, using in history, apply to 10rail cars one train sets, and maximum applying 224% sections of passengers congested that consideration is to be needed. So 2004, SeoulMetro improved technology and basic design of PSD at ATS section. Based on this, from 2005.4 to 2006.6, using subway 2lines per 12stations set the model installation(full type 11stations, half type 1station) After installing in case of success, it is going about to suggest that effective analysis and hereafter subject.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.985-992
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• 2008

A turnout system which permits trains to pass from one track to another is a combination of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 180km/h, at conventional lines by the year of 2010. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefore, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, evaluation of noise characteristics around the improved turnout system was performed through the field measurements. Field measurements of noise around the conventional and the high-speed turnout system were also carried out for the comparison.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1000-1005
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• 2008

A turnout system which permits trains to pass from one track to another is a combination of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and switch machines for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 180km/h, at conventional lines. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefor, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, evaluation of Vibration characteristics around the improved turnout system was performed through the field measurements. Field measurements of Vibration around the conventional and the high-speed turnout system were also carried out for the comparison.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.49-60
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• 2017

As well as the strength check, fatigue life check is also mainly required for designing mooring lines of the floating structures. In general, forces which induce dynamic structural response significantly affect to fatigue design of the mooring lines. So, waves are mainly considered as the governing loading for fatigue design of the mooring lines. In this study, characteristics of the fatigue damage of the mooring lines for submerged floating tunnels (SFT) under irregular waves are investigated. For this study time domain hydrodynamic analysis is used to obtain motion of the tunnel and tension and stresses of the mooring lines under the specific environmental conditions. Also, the Rainflow-counting method, the Palmgren-Miner's rule, and S-N curves for floating offshore structures presented by DNV recommendation is applied to calculate the fatigue damage due to the fluctuating stresses. Referring to the design plactice of the tendon pipes for TLP (tension-leg platform), which is very similar structural system to SFT, it is assumed that a 100 year return period wave attacks the SFT systems during 48 hours and the fatigue damages due to the environmental loading are calculated. Following the analysis sequence, the effects of the tunnel draft, spacing and initial inclination angle of the mooring lines on the fatigue damage under the specific environmental loadings are investigated.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.414-417
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• 2007

A methodology for XML documentation of the structural calculation document is presented to support manipulation of the design information on the internet. The text file format is chosen as a neutral format because it can be easily translated from office documents generated from engineering practice. The first word of each line is compared with the reserved numbering groups, and relative levels among the lines are defined to generate the hierarchically structured XML document of the text file. The demonstration subjected to sample general documents and structural calculation documents shows that the prototype application module based on the developed methodology can be adopted to build the database of design information which supports the safety management of infrastructures.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.277-284
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• 1998

LPG refueling include a lot of risk done by human beings, dealing with highly combustible gas, so, during the refueling, the leakage initiated by human errors can result in a catastrophic accident. Therefore, this research tried to show what kind of tasks would include the high probability of the human errors and what should be considered for effective safety management in the LPG refueling. At first, 4 typical cases were taken through surveying various accident cases, and then a prototype of the refueling task was presented. And each task was analysed by FTA and ETA. The results showed that overpressure occupies 64.64% of the major reasons for gas leakage, and its probability was approximately 6.62E-06. Among the tasks, gas leakage resulted from mal-assembly of lorry hoses had the highest rate, and human errors related to opening and closing valves of pipe lines were most frequent. Also, the effects of confirming tasks were analyzed quantitatively.