• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.61-68
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• 2011

The circuit breaker of power distribution board is essential part for the protection of electrical disaster from load short, trouble of power system. For the normal operation of circuit breaker, trip coil of the circuit breaker can cut the mechanical contact of circuit breaker from the detection of power system troubles. This paper presents a design and experimental results of trip coil fault detection system for the real time monitoring of the circuit breaker. The designed system is consisted by the trip coil fault detector which is connected to the each circuit breaker and remote monitoring unit. The trip coil fault detector can detect the impedance and operating voltage of the trip coil, and the detected values are compared with the normal state. And the remote monitoring unit can be connected to the 32 channels of trip coil fault detectors by serial communication. From the designed system, the fault and normal states of the trip coil can be remotely monitored in real time. The designed system is verified by the practical circuit breaker of power distribution board. And the results shows the effectiveness of the designed system.

• Journal of the Korean earth science society
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• v.28 no.1
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• pp.14-23
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• 2007

The purpose of this study was to investigate beginning earth science teachers' perceptions about Learning in Geologic Field Trip. The hundred and sixteen high school earth science teachers who were in the training for their promotion answered the questionnaire of Learning in Geologic Field Trip. It was divided into five parts: needs and educational values, teachers' experiences and their difficulties, and desirable teaching methods of Learning in Geologic Field Trip. Results indicated that the participants perceived Learning in Geologic Field Trip important in earth science education and responded positively to the educational values of Learning in Geologic Field Trip. Most of the beginning teachers had experience of geologic field trip, but did not learn how to teach it to their students during the geologic field trip in the pre-service training program. It was shown that only a few teachers had experience of geologic field trip and of teaching students in the outdoor of geologic fields after they became a classroom teacher. Most of the participants perceived that teaching students about the geologic field trip is difficult because of lack of their experience. In order to overcome the difficulty, teachers suggested that they need to learn how to teach the geologic field trip to students through their in-service training. leachers suggested that a desirable teaching method of the geologic field trip is to provide teachers with a teacher's manual including geological explanation and information about field trip sites before their visit so that they can scaffold it and facilitate the students' cooperative group activity during the field trip. As a follow up activity, the participants agreed that the presentation and discussion about the results should concur.

• Korean Journal of Materials Research
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• v.19 no.6
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• pp.293-299
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• 2009

The microstructures and mechanical properties of Dual Phase (DP), Transformation-Induced Plasticity (TRIP), and Quenching & Partitioning (Q&P) steels were investigated in order to define the strengthening mechanism of 0.2 C steel. An intercritical annealing between Ac1 and Ac3 was conducted to produce DP and TRIP steel, followed by quenching the DP and TRIP steel being quenched at to room temperature and by the TRIP steel being austemperingaustempered-air cooling cooled the steel toat room temperature, respectively. The Q&P steel was produced from full austenization, followed by quenching to the temperature between $M_s$ and $M_f$, and then enriching the carbon to stabilize the austenite throughout the heat treatment. For the DP and TRIP steels, as the intercritical annealing temperature increased, the tensile strength increased and the elongation decreased. The strength variation was due to the amount of hard phases, i.e., martensite and bainite, respectively in the DP and TRIP steels. It was also found that the elongation also decreased with the amount of soft ferrite in the DP and TRIP steels and with the amount of the that was retained in the austenite phasein the TRIP steel, respectively for the DP and TRIP steels. For the Q&P steel, as the partitioning time increased, the elongation and the tensile strength increased slightly. This was due to the stabilized austenite that was enriched with carbon, even when the amount of retained austenite decreased as the partitioning time increased from 30 seconds to 100 seconds.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.273-276
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• 2008

In this study, microstructure and distribution of alloy elements were investigated in thermo-mechanically processed C-Mn-Si transformation induced plasticity (TRIP) steels. The microstructures of TRIP steels were investigated by using advanced analysis techniques, such as three dimensional atom probe tomography (3D-APT). At first, the microstructure was observed by using TEM. TEM results revealed that microstructure of C-Mn-Si TRIP steel was composed of ferrite, bainte, and retained austenite. 3D-APT was used to characterize atomic-scale partitioning of added elements at the phase interface. In the retained austenite phase, Ti and B were enriched with C. However, there was no fluctuation of Mn and Si concentration across the interface. Through these analysis techniques, the advanced characteristics of constituent microstructure in C-Mn-Si TRIP steels were identified.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.499-500
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• 2007

The existing digital protection relay is continuously growing with an improvement in technology. In this paper, we propose the development of the digital protection relay which displays the trip area in real time. In most of the digital protection relays monitor whether analog signal enters into the pre-determined trip area, but those aren't provide the trip area information for a operator in real time. Therefore, if the digital protection relay continuously displays the trip area in real time, the operator analysis power system status easily. This paper particularly introduces selective ground protective relay and differential protective relay with trip area and presents a method of providing the trip area information to operator in real time.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.1
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• pp.55-70
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• 2018

Recently, as shared transportation services has expanded, integrated mobility services that link personal transportation and public transportation are paid attention. To do this, it is necessary to analyze trip mode chaining behavior. This study analyzed the characteristics of the trip mode chaining behavior using the 2010 travel diary survey in Seoul, and analyzed factors to affect mode choice of trip chaining through the multinomial logit model. The transportation means were classified into passenger cars, city buses, intercity buses, railways, taxis, and others, and 25 trip mode chaining types were identified. Among them, the trip share connected between city bus and railways was the highest. It was also found that the trip mode chaining occurred mainly at commuting and in the morning and afternoon peak. According to the model results, the mode choice of trip chaining is significantly influenced by individual attributes (sex and age), household attributes (car ownership and income), trip attributes (trip purpose, trip time and trip length), and arrival area attributes (number of subway lines and bus lines, ratio of commercial area, land use mix and central region).

• Journal of the Korean institute of surface engineering
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• v.46 no.1
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• pp.42-47
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• 2013

The strain-induced phase transformation from austenite to martensite is responsible for the high strength and ductility of TRIP steels. However high strength steels are susceptible to hydrogen embrittlement. This study aimed to evaluate the effects of hydrogen on the behavior of hydrogen delayed fracture in TRIP steel with hydrogen charging conditions. The electrochemical hydrogen charging was conducted at each specimen with varying current density and charging time. The relationship between hydrogen concentration and mechanical properties of TRIP steel was established by SP test and SEM fractography. The maximum loads and displacements of the TRIP steel in SP test decreased with increasing hydrogen charging time. The results of SEM fractography investigation revealed typical brittle mode of failure. Thus it was concluded that hydrogen delayed fracture in TRIP steel result from the diffusion of hydrogen through the ${\alpha}$' phase.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.7-19
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• 2011

Using 2006 metropolitan household travel survey data, this study analyzes trip behaviors based on a concept of trip chains using both trip purpose and number of trip linkages. For the analysis, trip chains are classified into two groups depending on including commute trips. Each group is further classified into a single linkage (i.e., Origin-Destination trips without any intermediate stop-by) and multiple linkages (Origin-Destination trip with at least one intermediate stop-by). The analysis is conducted using the two-step Nested Logit Model. Computational results identifying the characteristics of single and multiple linkages show that the young, male and office employee drivers tend to have more multiple linkages than single linkages in their trips. In contrast, it is shown that a driver whose monthly income is less than 3,000,000 Korean Won with a longer commute time more likely to make a trip chain with single linkages (p<0.0001).

• The Journal of Information Systems
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• v.28 no.4
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• pp.49-64
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• 2019

Purpose The purpose of this paper is to observe the relative priorities of importances among IT services for Smart tourism as well as the relative priorities of importances among ways for developing the IT Services. Design/methodology/approach AHP analysis model was designed with 3 layers in order to recognize the relative importances priorities of IT services and the ways developing the IT services in Smart tourism. The factors in the top layer consist of Pre-trip IT services, During-trip IT services and Post-trip IT services. The lower factors in second layer of the Pre-trip IT services consists of Tourism information search, Online reservation and Price comparison. The lower factors of the During-trip IT services consists of Context recognition, Virtual Reality and Drone Application. The lower factors of the Post-trip IT services consists of Interactive Sharing and Tagging. The factor of third layer, the ways of developing the IT services consist of Company leading, University leading and Industry-University Collaboration. The structural questionnaire based on the AHP analysis model was designed and used to survey experts in IT and tourism areas. The collected data by the question investigation was analyzed by AHP analysis technique. Findings The importance priority of During-trip IT service was highest among in the three type IT services of tourism life cycle. The importance priority of Price comparison service was highest among IT services for Pre-trip. The importance priority of the Context recognition service was highest among IT services for During-trip. The Interactive sharing service was highest among IT services for Post-trip. It would be confirmed for the IT service development ways of Company leading to be suitable for most of the It services, such as Tourism information search, Online reservation, Price comparison, Context recognition, Virtual reality, Drone application, Interactive sharing.

• Tunnel and Underground Space
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• v.25 no.6
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• pp.534-542
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• 2015

Round trip activity occurs discretely due to the abrasion of drill bit in the deep drilling project. Round trip has great impact on the drilling performance because it takes more time to change a drill bit as the depth goes deeper. Therefore, a reliable prediction technology of the round trip should be secured for feasibility analysis and effective management of the drilling project. Lee et al. (2013) developed the TOSA (round trip occurrence simulation algorithm) which can analyze the depth and timing of round trip occurrence at each abrasion state of bit. However, TOSA has weakness that it takes long time for simulation because the number of simulation increase exponentially as increasing the number of simulation section. This study developed the TOSA based round trip performance prediction module using genetic algorithm for simulating in a short time and verified simulation results.