• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.16-28
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• 2014

This paper presents a novel high-power-factor circuit topology of AC to AC current-fed type high frequency resonant inverter which includes the function of power factor correction(PFC) in the proposed inverter to operate the AC input block with high power factor. The proposed circuit topology of AC to AC current fed type high resonant inverter removes DC link electrolytic capacitor and has also the one of power factor correction(PFC) in the inverter circuit without an additional PFC circuit since the input current by constituting it in parallel as an unit inverter, which assumes the class-E high frequency resonant inverter of conventional current-fed type, flows in the form of the resultant current flowing through each constant current reactor($L_{d1}$, $L_{d2}$). The circuit analysis of proposed inverter is generally described by adopting the normalized parameters and the evaluation of its operating characteristics are conducted by using the parameters such as the ratio of switching and resonant frequency(${\mu}$), coupling coefficient(k) and so on. An example of procedure for circuit design based on the characteristic values obtained from the theoretical analysis is presented. To confirm the validity of the theoretical analysis, the experimental results are also presented. In the future, the proposed inverter shows it can be practically used as power supply system for induction heating application, DC-DC converter etc.

• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.583-592
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• 2011

The radiological characteristics for waste classification were assessed for neutron-activated decommissioning wastes from a CANDU reactor. The MCNP/ORIGEN2 code system was used for the source term analysis. The neutron flux and activation cross-section library for each structural component generated by MCNP simulation were used in the radionuclide buildup calculation in ORIGEN2. The specific activities of the relevant radionuclides in the activated metal waste were compared with the specified limits of the specific activities listed in the Korean standard and 10 CFR 61. The time-average full-core model of Wolsong Unit 1 was used as the neutron source for activation of in-core and ex-core structural components. The approximated levels of the neutron flux and cross-section, irradiated fuel composition, and a geometry simplification revealing good reliability in a previous study were used in the source term calculation as well. The results revealed the radioactivity, decay heat, hazard index, mass, and solid volume for the activated decommissioning waste to be $1.04{\times}10^{16}$ Bq, $2.09{\times}10^3$ W, $5.31{\times}10^{14}\;m^3$-water, $4.69{\times}10^5$ kg, and $7.38{\times}10^1\;m^3$, respectively. According to both Korean and US standards, the activated waste of the pressure tubes, calandria tubes, reactivity devices, and reactivity device supporters was greater than Class C, which should be disposed of in a deep geological disposal repository, whereas the side structural components were classified as low- and intermediate-level waste, which can be disposed of in a land disposal repository. Finally, this study confirmed that, regardless of the cooling time of the waste, 15% of the decommissioning waste cannot be disposed of in a land disposal repository. It is expected that the source terms and waste classification evaluated through this study can be widely used to establish a decommissioning/disposal strategy and fuel cycle analysis for CANDU reactors.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.6
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• pp.799-811
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• 2006

As an alternative measure to replace reactive stance with proactive one, a risk based management scheme has been commonly applied to enhance public satisfaction on water service by providing a higher creditable solution to handle a rehabilitation problem of pipe having high potential risk of leaks. This study intended to examine the feasibility of a simulation model to predict a recurrence probability of pipe leaks. As a branch of the data mining technique, probabilistic neural network (PNN) algorithm was applied to infer the extent of leaking recurrence probability of water network. PNN model could classify the leaking level of each unit segment of the pipe network. Pipe material, diameter, C value, road width, pressure, installation age as input variable and 5 classes by pipe leaking probability as output variable were built in PNN model. The study results indicated that it is important to pay higher attention to the pipe segment with the leak record. By increase the hydraulic pipe pressure to meet the required water demand from each node, simulation results indicated that about 6.9% of total number of pipe would additionally be classified into higher class of recurrence risk than present as the reference year. Consequently, it was convinced that the application of PNN model incorporated with a data base management system of pipe network to manage municipal water distribution network could make a promise to enhance the management efficiency by providing the essential knowledge for decision making rehabilitation of network.

• Bulletin of the Korean Mathematical Society
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• v.30 no.1
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• pp.71-77
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• 1993

Every ring considered in the paper will be assumed to be commutative and have a unit element. An ideal A of a ring R will be called primal if the elements of R which are zero divisors modulo A, form an ideal of R, say pp. If A is a primal ideal of R, P is called the adjoint ideal of A. The adjoint ideal of a primal ideal is prime [2]. The definition of primal ideals may also be formulated as follows: An ideal A of a ring R is primal if in the residue class ring R/A the zero divisors form an ideal of R/A. If Q is a primary idel of a ring R then every zero divisor of R/Q is nilpotent; therefore, Q is a primal ideal of R. That a primal ideal need not be primary, is shown by an example in [2]. Let R[X], and R[[X]] denote the polynomial ring and formal power series ring in an indeterminate X over a ring R, respectively. Let S be a multiplicative system in a ring R and S$^{-1}$ R the quotient ring of R. Let Q be a P-primary ideal of a ring R. Then Q[X] is a P[X]-primary ideal of R[X], and S$^{-1}$ Q is a S$^{-1}$ P-primary ideal of a ring S$^{-1}$ R if S.cap.P=.phi., and Q[[X]] is a P[[X]]-primary ideal of R[[X]] if R is Noetherian [1]. We search for analogous results when primary ideals are replaced with primal ideals. To show an ideal A of a ring R to be primal, it sufficies to show that a-b is a zero divisor modulo A whenever a and b are zero divisors modulo A.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.299-308
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• 2001

The company invests its time and money for temporary maintenance to satisfy the fast change of the computer use environment and the user's demands. Therefore, various problems occur including low performance because of duplication of codes and unstable structures from the restructuring and redevelopment. Furthermore, if a developer, who did not participate in initial process of development, wrote additional program codes to upgrade or restructure, it would cause many problems such as lack or lose of development documentation, understanding of documentation and reuse of existing program language. This study, Object-oriented Refactoring Process, suggests that the developers can reuse object unit to overcome the limit of the reusing code. In addition, this paper shows case study to verify our process by adjusting the project called "D2D", which is a case tool for developing windows system from Company D. Our works get positive results such as improvement of system pelfonnance, decreased cost of development and maintenance and optimizing structure and class.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.12 no.1
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• pp.21-29
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• 2005

Purpose: The purpose of this study was to identify the frequency with which nursing interventions according to domains and classes, and core nursing interventions of the Nursing Intervention Classification (NIC) were performed by nurses on orthopedic surgery nursing units. Method: For this purpose, the third edition of NIC was used. Of the 486 nursing interventions, 424 were selected at 75% consent by experts. Data were collected from June, 2003 to July, 2003 5 hospitals and 69 nurses(return rate : 95.8%) in Gwang-ju and Chonnam region. 5 point Likert scale describing frequency was used. Results: The most frequently performed domain was 'physiological : basic'($2.97{\pm}.60$), followed by 'health system'($2.65{\pm}.65$) and 'physiological : complex'($2.55{\pm}.46$). The most frequently performed class was 'activity and exercise management'($3.82{\pm}.89$), followed by 'immobility management'($3.64{\pm}.62$), 'skin/wound management'($3.41 {\pm}.60$), 'physical comfort promotion'($3.23{\pm}.68$) and 'thermoregulation'($3.01{\pm}.91$). The most frequently performed nursing intervention was 'medication administration' ($4.96{\pm}.21$), followed by 'medication administration : intravenous'($4.93{\pm}.31$), 'analgesic administration'($4.91{\pm}.51$), 'pain management'($4.87{\pm}.34$) and 'medication administration : intramuscular'($4.78{\pm}.68$). Conclusion: In conclusion, the third edition of NIC was found to be a general and comprehensive classification system for application on orthopedic surgery nursing units. These findings will help in building of a standardized language for orthopedic surgery nursing units and enhance the quality of nursing care.

• Membrane and Water Treatment
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• v.9 no.2
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• pp.69-77
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• 2018

The use of membrane as an innovative technology for water treatment process has now widely been accepted and adopted to replace the conventional water treatment process in increasing fresh water production for various domestic and industrial purposes. In this study, ultrafiltration (UF) membranes with different formulation were fabricated via phase inversion method. The membranes were fabricated by varying the polymer concentration (16 wt%, 18 wt%, 20 wt%, and 21 wt%). A series of tests, such as field emission scanning electron microscope (FESEM), pore size and porosity, contact angle, and zeta potential were performed to characterize the membranes. The membrane performance in terms of permeation flux and rejection were evaluated using a laboratory bench-scale test unit with mine water, lake water and tube well as model feed solution. Long hour filtration study of the membranes provides the information on its fouling property. Few pore blocking mechanism models were proposed to examine the behaviour of flux reduction and to estimate the fouling parameters based on different degree of fouling. 21 wt% PVDF membrane with smaller membrane pore size showed an excellent performance for surface water treatment in which the treated water complied with NWQS class II standard.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.5
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• pp.79-86
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• 2014

A turbopump real-propellant test facility(TPTF) is to verify the performance of a turbopump unit(TPU) based on liquid oxygen and kerosene. One of the most important sub-facilities is a hot-gas generation system which makes the driving force of the TPU with an alcohol burner. The alcohol burner generates the required flow rates and temperature at the facility using high pressure air and ethanol. In the study, the verification tests of the alcohol burner which was manufactured entirely with domestic technology were performed and fabrication technique and operation skill for the burner could be obtained ahead of the construction of the facility. Two burners will be operated simultaneously for the real-propellant test of 75tf class turbopump and satisfy the power requirement from the turbine of the TPU.

• Hwankyungkyoyuk
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• v.13 no.1
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• pp.75-86
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• 2000

The purpose of this study is to analyze the content of environmental inquiry activities and values of elementary school students written in their reports of the Energy Environment Inquiry Activity Contest which is a unit contest of the Youth Science Festival held annually in Korea and get some ideas for the valuable way of Korean environmental education. 10 teams' reports were gathered and the locality, class study area, inquiry theme, inquiry method and values were analyzed and introduced as case studies to get some insights to teach elementary school students environmental values through inquiry activities of science subject approach. Each teams set various inquiry themes in the content domain of energy resources and earth environment conservation focusing on each team's geographical characteristics and occurring environmental problems in their local areas. There were 16 sentences representing technocentrism and 12 sentences representing ecocentrism. 5 of 10 teams showed both of technocentrism and ecocentrism in their reports. But their was only scientific knowledge without any environmental values in one team's report. Inquiry activity is a good teaching-learning method to develop environmental literacy. There should be environmental values involved as far as it is the environmental inquiry activities using environmental subject matter. The result of this study proposes that environmental educators should actively intervene for inquirers to set a stage in the whole process to search for an alternative to solve environmental problems involved in their project activities. The reason is because the environmental education in the elementary school is established to operate by the infusion way into various subjects already existed in the Korean curriculum.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.12
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• pp.987-997
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• 2019

Walk score, walkablity index of built environmental condition, has developed and used in everyday life in United States. The purpose of this study is to produce walk score in Seoul, and to develop computer-based walk score system for improving it's usage. This study covers city of Seoul, and the unit of spatial analysis is 100m × 100m grid cell. This study uses same methodology with walk score in US, the Geographic Information Systems(GIS) is used for calculating the values of walk score(N=58,062). This study implemented Java-based system that utilizes walk score dataset(latitude, longitude, and walk score). This system provided search functions including both lat/long-based and address-based options. Meanwhile, this system was designed to provide the closest value of walk score in dataset if location did not match the certain points in dataset. This study has significance to provide walk score system being easily available to all.