• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.261-267
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• 1995

Using the dual of a categorical definition of an injective envelope, Enochs defined an injective cover. In this paper we will show how injective covers can be used to characterize several well known classes of rings.

• Kyungpook Mathematical Journal
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• v.18 no.1
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• pp.85-89
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• 1978

In this paper locally uniform spaces have been characterized through covers. It has been shown that both the approaches are equivalent.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2005.04a
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• pp.81-84
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• 2005

• Journal of Convergence for Information Technology
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• v.8 no.1
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• pp.227-233
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• 2018

The purpose of this study was to develop a warm cover for greenhouse with excellent thermal insulation and to propose ways of commercialization of the product. Feathers were used as filling materials because they formed the air layer to enhance insulation. Instead of downs for clothing or other textile products, we used disposed feathers. The developed product covers the outside of the greenhouse to keep the crops warm. It has multiple layers including feathers as filling materials, padding, inside fabric, heat insulation materials and outer fabric. It has proven to improve the insulation ratio. We developed other kinds of warm covers that are applicable to the inside of the greenhouse or the small houses in the greenhouse. Also, R&D system of educational industrial complex enables us to commercialize the products and building marketing strategies for them. This technology contributes to the expansion of energy-saving facilities for farmers, and it can serve the development and spread of various products utilizing feather.

• Journal of the Korean Geographical Society
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• v.45 no.3
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• pp.360-374
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• 2010

The distributions, factors, and vegetation covers of debris slopes and changes of debris at the eastern Ongjeom-ri, Cheongsong-gun are analyzed. The important factors influencing on the developments of the slopes are felsites having advantages to the developments of cliffs and supply of enough debris, and the relatively long days below zero temperatures promoting the physical weathering processes. The distributional areas of the slopes at southern and western slopes are more extensive than those of northern and eastern slopes due to the active water evaporation by high insolation. The Ga area at eastern Ongjeom-ri has experienced the steady decreases of area of the slopes due to the vegetation covers and shows the increasing rates of vegetation covers of $431.0m^2/yr$ as averaged values. However, it is estimated at the Na area using terrestrial LIDAR that 1 or 2 debris were moved or displaed per year in slope.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.5
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• pp.439-445
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• 2012

Only the sand carriers fitted with hopper doors can remove their hatch covers in current regulations. However, there is no sand carriers fitted with hopper doors in korea. Through the analysis of accidents, inspection of equipment installed on ships, and evaluation of stability and seakeeping performance concerning the sand carriers, it is expected that the current exemption requirement is modified for hatch covers for sand carriers. As the result, this paper proposed the removal of hatch covers and be fitted by tarpaulin instead to protect water ingress into the holds. This can be done by making the holds smaller designed to be filled full until the top of the hold without exceeding loadline. Also, the bilge pumps should have the sufficient capacity of pumping water out in the early stage of sand-water mixture to wetted condition in approximately 1 hour and be operationally ready in every voyage conditions.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.807-816
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• 2012

The Three Mile Island Unit 2 (TMI-2) accident has been studied extensively, as part of both post-accident technical assessment and follow-up computer code calculations. The models used in computer codes for severe accidents have improved significantly over the years due to better understanding. It was decided to reanalyze the severe accident scenario using current state of the art codes and methodologies. This reanalysis was adopted as a part of the joint standard problem exercise for the Atomic Energy Regulatory Board (AERB) - United States Regulatory Commission (USNRC) bilateral safety meet. The accident scenario was divided into four phases for analysis viz., Phase 1 covers from the accident initiation to the shutdown of the last Reactor Coolant Pumps (RCPs) (0 to 100 min), Phase 2 covers initial fuel heat up and core degradation (100 to 174 min), Phase 3 is the period of recovery of the core water level by operating the reactor coolant pump, and the core reheat that followed (174 to 200 min) and Phase 4 covers refilling of the core by high pressure injection (200 to 300 min). The base case analysis was carried out for all four phases. The majority of the predicted parameters are in good agreement with the observed data. However, some parameters have significant deviations compared to the observed data. These discrepancies have arisen from uncertainties in boundary conditions, such as makeup flow, flow during the RCP 2B transient (Phase 3), models used in the code, the adopted nodalisation schemes, etc. In view of this, uncertainty and sensitivity analyses are carried out using simulation based techniques. The paper deals with uncertainty and sensitivity analyses carried out for the first three phases of the accident scenario.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.124-133
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• 2017

In the current lighting market, LEDs that have a high luminous efficiency, a long life and consume less power have emerged as next generation lighting. Owing to various designs and sizes of LEDs, the production process of existing LEDs involves many tasks that require manual labor; hence, the assembly of LEDs necessitates manpower. Because of the use of manpower, the production costs of LEDs increases and production efficiency decreases. Recently, the assembly parts of LEDs have been standardized for minimizing manual labor, and an LED is developed as an LED panel. The automatic assembly system produces LED convergent lighting by assembling two LED panels and one diffusion cover. To increase the production efficiency of the LED convergent lighting module, it is important that the development of a feeder can continuously supply the LED panels is required, and whose design has sufficient stability. The automatic assembly system of the LED convergent lighting module consists of two feeders, which convey LED panels and diffusion covers to a main conveyor, which assembles the lifted panels and covers. In this study, structural analysis and fatigue life for forced loads on the conveyer line of the feeder in the process of lifting LED panels and diffusion covers of each feeder, is analyzed. In addition, the drive of the belt constituting the conveyor line of each feeder is simulated, and the dynamic characteristics of the belt is analyzed using the virtual engineering method.

• Korean Institute of Interior Design Journal
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• v.22 no.1
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• pp.247-255
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• 2013

In this study, the colors and characteristics of Gwangbok-ro of Busan were analyzed in the standpoint of local images based on the examination of the facade designs of stores along the road of Gwangbok-ro, Busan a main street with massive population flow. To that end, the facades of stores, correlation with the city, color and locality were examined, and after the status of facade designs in Gwangbok-ro were identified through case survey by it, color images were analyzed. For color analysis, Munsell color system was used as basic tool. As a result of examining the colors in Gwangbok-ro area, the following status could be analyzed on 3 attributes of hue, brightness and chroma: First, analysis results of hue indicated that dominant color that covers 70% or more of the area represented mid brightness and low chroma in GY(36.1%) series, subsidiary color which covers 25% or more of the area mid brightness and low chroma in YR(26.5%) series, and accent color that covers less than 5% of the area high brightness and low chroma of GY(40%) series. Second, in brightness analysis, dominant color mostly represented mid brightness, subsidiary color mid brightness and accent color high brightness respectively. In particular accent color showed more intensive crowding phenomenon in high brightness. Third, as for chroma, dominant color, subsidiary color and accent color all are gathered in low chroma, however in small number of accent colors, peculiar high chroma appeared notable. In conclusion, the colors of Gwangbok-ro area analyzed based on the facade design of the stores along the road in this study were superficial colors that reflect the life of people in the area, artificial colors by improvement of the local environment. This study is meaningful in that the image of Gwangbok-ro was found through building colors in one part of the city Busan. It is judged that the study results would become useful as reference document in planning out environment colors later on.

• Journal of Korean Elementary Science Education
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• v.24 no.5
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• pp.620-626
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• 2005

In this study, we conducted a comparative study to investigate the curriculums on electricity and magnetism between in Korean and in Ontario elementary schools in Canada with respect to connectivity and difference among course materials with grades. We compared textbooks that contain the contents about electricity and magnetism, and connectivity in curriculums that were relevant to the science content system in each country. We report the following differences in the curriculums on electricity and magnetism in each country. First, it turns out that science is taught from the first grade in Ontario, while it is taught from the third grade in Korea. Second, Ontario covers electricity and magnetism only in science curriculum, while Korea covers the same topics both in the science and practical arts curriculum. Third, while the curriculum in Korea introduces 'a magnet' in the third grade, 'electricity' in the fourth and the fifth grade, and 'an electromagnet' in the sixth grade, while the curriculum in Ontario covers the concept of energy from the first grade. As the grades go up, the contents of electricity and magnetism tend to be more deepen. It also emphasizes enhancing students' ability that they can communicate what they learn about technology with others, and that they can apply their knowledge to other fields as well. Based on this study of the Ontario curriculum, we suggest that it is necessary for us to n Science curriculum from the first grade, so that the students can learn science from the early grade, without a need to run another subject, like practical arts. We also found that the Korean curriculum has an interesting structure for the young students to learn to apply their knowledge to the real life immediately, based on an idea that the topic of 'Manipulating the electric appliances' in practical arts curriculum moves to the Science.