• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.25-34
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• 2013

The paper reviews the state of art in the design of liquefaction processes for the production of liquified natural gas, and addresses key design aspects to be considered in the design and how these design issues are systematically reflected in industrial applications. Various design options to improve energy efficiency of refrigeration cycles are discussed, including cascaded or multi-level pure refrigeration cycles which are used for covering wide range of cooling temperature, as well as mixed refrigerant cycle which can maintain a simple structure. Heat integration technique has been used for graphically examining differences of commercial cycles discussed in this paper, while energy efficiency and economics of commercial liquefaction processes has been summarized. Discussion also has been made about how to select the most appropriate set of drivers for compressors used in the liquefaction plant.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.163-174
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• 2004

A number of experiments were performed to investigate the punching shear strength of flat plate-column connections. According to the experiments, the punching shear strength varies significantly with design parameters such as the column size of the connection, reinforcement ratio, and boundary condition. However, current design methods do not properly address the effects of such design parameters. In the present study, a theoratical approach using Rankine's failure cirterion was attempted to define the failure mechanism of the punching shear According to the study, the failure mechanism can be classified into the compression-controlled and the tension-controlled, depending on the amount of bottom re-bars placed at the connection, and the punching shear strength is also significantly affected by the flexural damage of slab. Based on the finding, a new strength model of punching shear was developed, and verified by the comparisons with existing experiments and nonlinear finite element analyses. The comparisons show that the proposed strength model addressing the effects of various design parameters can predict accurately the punching shear strength, compared to the existing strength models.

• Journal of the Korean earth science society
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• v.28 no.4
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• pp.405-414
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• 2007

This study examined students' achievement of Earth science in the Trends in International Mathematics and Science Study (TIMSS) that was conducted with 46 participating countries in 2003 and analyzed average percent-correct items for Earth science were analyzed in terms of subcategory, item type and cognitive domain. In addition, items showing a gender difference and a big difference in the test scores of Korean and international students were analyzed. Korean students performed higher than the international average, especially in the astronomy-related topic and in the cognitive domain of 'reasoning and analysis'. In an analysis of the five items that Korean students scored lower than the international average, Korean students performed not so well in demonstrating what they understood with drawings and writings. Korean female students showed a difficulty more than male students did in multiple-choice items that asked recalling of factual knowledge and demonstrated lack of confidence in the items that they have not learned yet. Based on the result content organization of Earth science curriculum and ways to improve teaching and loaming methods were recommended.

• Korean Journal of Social Welfare
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• v.68 no.2
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• pp.185-211
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• 2016

This study analyzes key word networks of the papers which are published at Korean Journal of Social Welfare issued by Korean Academy of Social Welfare from 1979 to 2015. It aims at investigating the trends of social welfare researches in Korea by dividing the given period into two: 1979-2000 and 2001-2015. It shows the trends in three ways: methodologies, subjects, and intellectual structures. In order to identify intellectual structure, it calculate centrality indices basing on co-appearance frequency of key words. It also derives some values which explain relationship structure of key words by using pathfinder algorithm, and finally visualizes the intellectual structures by using the NodeXL program. Some implications of the findings of these analyses are discussed in the end.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.4
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• pp.63-71
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• 1989

Four series of reinforced concrete beams were tested to determine their shear cracking strengths and ultimate shear capacities. All beams were singly reinforced without shear reinforcement. The concrete strength was the prime variable which was varied from 247 to $708kg/cm^2$(8500 to 10000 psi). Within each series the shear span-to-depth ratio was varied from 2 to 5, while concrete strength was held constant. Test results indicate that the effect of concrete strength on shear capacities is varied as the shear span-to-depth ratio is changed. Furthermore, the current shear design provisions do not provide a consistency with respect to estimating shear capacities of reinforced concrete beams. By introducing the shear failure mode index, a new equation is proposed to predict ultimate shear strengths of reinforced concrete beams without web reinforcement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.183-190
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• 1993

It is desirable to utilize the result after studying the rainfall characteristics including the latest observation data in the districts for the sake of establishment of the more accurate plans for drainage or plans for hydraulic stuctures because the rainfall phenomena are different in their characteristics by regional groups and if we make a meteorological observation for a long period of time, the rainfall characteristics also change a great deal as compared with the preceding years. Therefore, we selected only the annual maximum rainfall from the self-recording rain gauge of the main rainfall observation station (Cheju, Sogwipo, Songsanpo) in the Cheju districts in the last twenty years, extracted the rainfall by actual measurement by the rainfall duration, and induced the optimal probable rainfall-intensity formulas by regional groups in the Cheju districts, taking advantage of the rainfall formulas being in wide use in general, that is, Talbot type, Sherman type, Japanese type, and new Semi-log type. As the result, the return periods at Cheju station appeared to be three years to five years and the optimal probable rainfall-intensity formula at Cheju station, Japanese type and outside the city, Talbot type; Sogwipo, Sherman type; Songsanpo, Talbot type respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.751-756
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• 2010

Ultrasonic nonlinearity is very sensitive to changes in material properties. This paper describes the study of the correlation between heat treatment and ultrasonic nonlinearity by taking nonlinear factors into consideration. A modified formula was proposed for ultrasonic velocity. This formula indicated that the changes occurring in nonlinearity during heat treatments cause changes in the ultrasonic velocity. The experimental results show that the relative nonlinearity parameters calculated from the modified ultrasonic velocities and the ratio of amplitudes of the second harmonic and fundamental wave are in good agreement. The experimental results prove that heat treatment can result in changes in material nonlinearity. Moreover, the relative nonlinearity parameter calculated from the modified velocity formula is has a large value. Since this parameter has high sensitivity to changes in nonlinearity, it can be used to represent the relative nonlinearity change calculated in this study by using the modified formula for ultrasonic velocity.

• The Journal of the Korea Contents Association
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• v.14 no.10
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• pp.350-360
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• 2014

The purpose of this study was to identify the moderating effect of resilience and hope among satisfaction of university, family cohesion, and perceived entrapment. It was conducted to measure research variables from 610 university students. The moderating effect according to resilience and hope was analyzed through hierarchical regression analysis and presented in graphs of significant moderating effect. As a result of analysis, first, there were significant relationship, among satisfaction of university, family cohesion, and perceived entrapment. Second, satisfaction of university and family cohesion had a significant negative effect on the perceived entrapment. Third, resilience had moderating effect within the relationship of university satisfaction and perceived entrapment. Forth, hope had moderating effect within the relationship of family cohesion and perceived entrapment. Implications of these results were explored in relation to the importance of resilience and hope that could be taken to reduce perceived entrapment.

• 한국해양학회지
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• v.25 no.1
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• pp.1-7
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• 1990

Seawater temperature, salinity, inorganic nutrients and the standing crop of phytoplankton species of the 841 water samples from the upper 125 m at 15-40 stations on the 6 semiannual cruises in the southwestern waters of the East Sea (Korea) were studied during the period from September, 1981 to October, 1984, Among the 235 taxa identified two pennate diatioms, cylindrotheca closterium and Nitzschia delicatissima, were the most common and dominant species. The multiple regression analyses between net phytoplankton abundance (dependent variable) and associated environmental factors(independent variables) were applied to the samples from the surface mixed-layer. In spring the coefficients for the seawater temperature was 1. to 4.2 times greater than those for salinity, while the coefficients for the salinity was 2.1 to 3.4 times greater than those for seawater temperature in autumn. Distribution seawater temperature in spring, and salinity in autumn. Schematically the zone of high standing crops moved about on the T-S diagram in a cyclic manner. The distribution of phytoplankton standing crop was quite closely associated with the hydrographic conditions among various kinds of environmental factors studied.

• Journal of Gifted/Talented Education
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• v.17 no.2
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• pp.280-306
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• 2007

The purpose of this study is to investigate the two assertions of hereditarianism and environmentalism in the intellectual abilities, which is one of the most important factors of giftedness, and thus to discuss and understand giftedness. As the result of various investigations about the two opposing opinions, it is general view that about 50% of the intellectual abilities are endowed by genetic factors, but they are not fixed life long but changed and developed by posterior experiences. In other word, it is said that giftedness itself of which an important factor is intellectual abilities is determined by heredity, but the degree of revelation of the potential faculty is determined by environmental factors. Therefore, the recent major concerns in this field seem to be on how to make unfold most the children's giftedness rather than arguments about the degree of genetic and environmental factors. It can be said that giftedness is sprung up and accelerated only when an excellent genetic factor and a special environmental factor are transacted dynamically and amplified exquisitely.