• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.1
• /
• pp.6-13
• /
• 2008

National standard system for calibrating current transformer(CT) up to primary current of 20,000A have been established. The system consists of 20,000 A AC high current source, CT comparator, standard CT, CT under test and CT burden. An AC high current is applied tn the primary windings of both the standard CT and the CT under test, and then the CT comparator measures the ratio error and the phase displacement by comparing the secondary currents of the two transformers. As a validity check for 20,000 A CT calibration system, the comparison with the two national standard institutes(NMIs) has been performed using same CTs. The comparison results of the CTs are consistent with those measured at two NMIs within 0.004 % for ratio error and 0.1 min for phase displacement in the primary current ranges of Ip = 10 - 20,000 A with a secondary current of Is = 5 A.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.2
• /
• pp.164-169
• /
• 2008

National standard system for calibrating voltage transformer(VT) up to primary voltage of 240 kV have been established in 2005. The system consists of voltage source, regulating unit, VT testing unit, standard VT, VT under test and VT burden. To verify and validate the performance for 240 kV VT calibration system, the comparison with the National Measurement Institute of Australia(NMIA) has been performed using same VTs. The comparison results of the VTs mesured at the Korea Research Institute of Stansdards and Science(KRISS) are consistent with those measured at NMIA within 0.002 % for ratio error and 0.14 min for phase displacement in the primary voltage ranges of Vp = 3300 V - 22000 V with a secondary voltage of Vs = 110 V.

• Journal of the Korean Institute of Educational Facilities
• /
• v.24 no.6
• /
• pp.27-36
• /
• 2017

Educational facilities have an affect to make a decently learning environment. After constructed, it needs a maintenance plan to keep the performance or function which provide the repair time, repair scope and ratio. But the fundamental data are so insufficient that the field worker can't provide the maintenance plan and has no choice use the other data which concerned with apartment or office building. Above all, the service life is indispensible to make a repair plan because the repair time and scope would be provided within the service life. This study aimed at providing the method to make a service life of component in educational facilities and applying the method into the roof proof and floor finishing. Results are shown that first, it is important to set the $1^{st}$ repair time after constructed. when it proposes the three ways with the probability approach, choice probability model and cumulative cost function. Second, the service life of roof proof is provided with about 35 years. In addition, the service life of the floor finishing is about 40 years. These result would be utilized to conduct the repair plan under the service life.

• Journal of the Korean Dietetic Association
• /
• v.18 no.4
• /
• pp.372-384
• /
• 2012

The purpose of this study was to provide a basic resource for establishment of hygienic management standards for meal delivery from the central kitchen to schools. Flow diagrams for delivery of food were analyzed, and time-temperature conditions of the food and environment were measured. Four different foods samples including Mexican salad, radish salad, stir-fried pork and vegetables, and stir-fried chicken and vegetables were collected after production and before service. Microbiological analysis was performed for aerobic plate counts (APC), Enterobacteriaceae, coliforms, E. coli, Salmonella spp., S. aureus, B. cereus, C. perfringens, and L. monocytogenes. After completion of production of cooked foods 2~3 hours were taken for the cooked foods to reach the temperature danger zone. Food temperatures at the meal service did not meet the recommended temperatures ($10/57^{\circ}C$) for conventional school food service systems. The highest APC counts were observed in radish salad (5.70 log CFU/g), followed by Mexican salad (5.18 log CFU/g). Enterobacteriaceae and coliform counts were within acceptable levels of those recommended by the UK Public Health Laboratory Service. No E. coli or pathogens were found. These results provide useful information for determination of microbiological hazards in school food service systems, and suggest that time-temperature control during delivery is necessary for the safety of cooked foods.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.151-156
• /
• 2008

The after 1974 capital region electric railroad is opened to traffic Koraill and Seoul metro adopt each other different power supply method and they operate and they are come. AC 25[kv] method voltage the insulation becomes larger standing distance highly, the case tunnel section which will introduce in the underground segment becomes on a large scale and the cost of construction increases to the city center and the underground segment adoption of DC method was many. To recent times with R-bar (Rigid-bar) introductions change of tunnel section the introduction of AC method came to be easy without in the underground segment. Operates sees in the electric protection where the Seoul metro and the Korail are different each other and, from the dead section segment the interior electric light to put out lights the passenger brings about inconveniently and the civil appeal which demands a power supply method unification occurs, within the company interchange electric railroad brazier safety improvement and maintenance expense curtailment etc. the flaw is original proposal, is a condition which finishes a feasibility study service about the power supply method fringe land. Interchange analysis of the DC electric railway it leads from the present paper and it compares under analyzing being it could be reflected to also the route which is in the process of actual using boil the strong point and a weak point of DC and AC method of the establishment route constructive at the time of and

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.29 no.2
• /
• pp.94-99
• /
• 2021

UTM is an air traffic management ecosystem under development for autonomously controlled operations of UAS by the FAA, NASA, other federal partner agencies, and industry. They are collaboratively exploring concepts of operation, data exchange requirements, and a supporting framework to enable multiple UAS operations beyond visual line-of-sight at altitudes under AGL 500ft in airspace where air traffic services are not provided. Minimum Safe Altitude is a generic expression, used in various cases to denote an altitude below which it is unsafe to fly owing to presence of terrain or obstacles. The European drone regulation mentions that the UAS is maintained within 120 metres from the closest point of the surface of the earth during flight, except when overflying an obstacle. This study attempted to develop a minimum flight altitude database system. Based on domestic and international rules and regulations on setting the minimum flight altitude it is expected that it can be applied to the operation of aircraft and unmanned aerial system in UTM environments for specific area in Korea.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.6
• /
• pp.1379-1386
• /
• 2018

Conventional underwater cameras used in fish farms can only shoot limited areas and are vulnerable to underwater contamination. There is also a problem with contaminated farms as surplus residues are deposited as a result of feed supply to farms' nets. This paper proposes underwater drones for underwater monitoring of fish farms and cleaning nets. If underwater drones are used for management of fish farms, underwater imaging, monitoring and cleaning of fish farms' nets can be possible. By using this technology, data can be collected by detecting changes in the environment of a fish farm and responding to changes that occur within a fish farm based on the data. In addition, the establishment of an integrated control system will enable to build efficient and stable smart farms.

• The Journal of the Korean dental association
• /
• v.57 no.9
• /
• pp.504-513
• /
• 2019

Dental education is gradually transitioning to competency-based education system, which aims to help dentists achieve certain core competencies by means of various systems, such as curriculum accreditation. This study examined satisfaction with dental school education and the differences in the perceived importance and self-assessment of competencies among general dentists, in an attempt to propose a desirable direction for dental education. A questionnaire was administered to new general dentists who graduated from a dental school within the past 10 years. The results of the survey were analyzed using the Importance-Performance Analysis to understand differences in dentists' perceptions. Overall satisfaction with education was low in terms of the curriculum's relevance to actual practice and its capacity for cultivating required competencies. Furthermore, many of the respondents strongly perceived the need to improve dental education. Additional investigations into the satisfaction with education showed no difference. Among the seven key competency domains, dentists perceived Health Promotion to be important and also assessed themselves as having high competence. However, regarding the perceived importance of the remaining domains, self-assessment of competence was low for Professionalism, Communication & Interpersonal Skills, Knowledge Base, Information Handling & Critical Thinking, Clinical Information Gathering, Diagnosis & Treatment Planning, and Establishment & Maintenance of Oral Health. The results of this study suggest that a competency-based education model should be developed and incorporated into dental education to set performance standards and to promote systematic self-assessment in order to foster the development of competence in dental students.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.34 no.11
• /
• pp.23-32
• /
• 2018

The purpose of this study is to establish a walking energy weighted ERAM model that can predict the pedestrian volume by the connection structure of the vertical and horizontal spaces within a three-dimensional building. The process of building a walking-energy weighted ERAM model is as follows. First, the spatial graph was used to reproduce three-dimensional buildings with vertical and horizontal spatial connection structures. Second, the walking energy was measured on the spatial graph. Third, ERAM model was used to apply weights with spatial connection properties in random walking environment, and the walking energy weights were applied to the ERAM model to calculate the walk energy weighted ERAM values and visualize the distribution of pedestrian flow. To verify the validation of the established model, existing and proposed spatial analysis models were compared to real space. The results of this study are as follows : The model proposed in this study showed as much elaborated estimation of pedestrian traffic flow in real space as in traditional spatial analysis models, and also it showed much higher level of forecasting pedestrian traffic flow in real space than existing models.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.35 no.1
• /
• pp.107-115
• /
• 2019

This research explores a historical trajectory of the Milwaukee Art Museum from its establishment to the third expansion over the last six decades. After established in 1957 by the architect, Eero Saarinen, this museum underwent three expansions led by three different architects including, David Kahler, Santiago Calatrava, and James Shields. Reasons for expanding the museum were varied. A lack of exhibition space, an absence of visual identity, and path interruption problem within urban contexts were the main factors of a series of expansion. Furthermore, this research points out that there are three issues in the process of the expansion. The first is connection issues between the downtown and the lakefront in which the museum has blocked the public flow. The second, there were controversies on the allocation of the expanded space among the main body of the decision including architects, curators, and stakeholders. The last one is relationships among architects. This is related to each architect's attitude toward the museum. Drawing on historical documents and interviews with the regional architects, I argue that the identity and values of the museum have changed over time through the expansions rather than having the invariable.