• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.3
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• pp.8-11
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• 1969

In the precision measurement of the voltage standing wave ratio (VSWR) or reflection coefficient by means of the slotted line technique, one of the important factors is the maximum error due to the discontinuities and multi-reflection in the slotted line. Particularly, this error becomes a critical factor when the VSWR or the reflection coefficient to be measured is very small. In this paper, the exact expression of this error is obtained by means of the Signal flow graph method.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.195-197
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• 2009

The role of environment-friendly and energy-efficient rail transportation is on the rise as a "sustainable transportation means" to cope with environmental changes that are major concerns around the world. Along with the environmental problems, the CO2 inhibition issue became critical for mankind to prepare global warming and high oil prices. It has come to a point where an alternate means are needed to revitalize plans including renewable energy, bicycle utilization, and prepare new solutions for decreasing number of cars within the city The personal rapid Transit(PRT) is the revolutionary future transportation means that can replace cars to deal with ever-increasing traffic congestions, vehicles, and environmental/energy problems. Expected as an efficient means, technology development has already taken place in developed countries such as U.S., England, and Germany. To meet the future demands, PRT installation around the nation's new and existing towns is being examined to produce important factors. The factors are produced for examining the availability of system requirements during design and construction practice.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.145-148
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• 2002

Membrane bioreactors for wastewater treatment must operate for long periods without chemical cleaning. This study investigates the critical flux concept introduced by Field et al. as a means for achieving this goal. We conducted two series of tests: at fixed transmembrane pressure(TMP) and at fixed permeate flux. set by a volumetric pump on the permeate. Comparison of constant pressure and constants flux tests under same conditions showed that the critical flux is almost identical to the limiting or pressure independent flux obtained in constant pressure. More generally, constant flux procedure below the critical flux avoids overfouling of the membrane in the initial stage and is more advantageous for membrane bioreactor operation.

• Korean Journal of Social Welfare
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• v.59 no.3
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• pp.253-280
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• 2007

This study explores the discoures of family and family policy in the legislative process of Strong Family Act. Critical discourse analysis was used. The results are follows. The Strong Family Act made family issue as a political agenda in spite of much critics. The characteristics of the family discourse in "strong family camp": 1) The emphasis on the moral principle in family 2) denial of deinstitutionalization of family 3) regarding the family problem as a moral and individual problem 4) regarding the state as managing and controling the family. The characteristics of the family discourse in "critical camp": 1) strong family discourse is related to "the family" ideology 2) regarding the family problem as a social, structural problem 3) regarding the state as subsiding, supplementing families. The characteristics of the family policy discourse in "strong family camp": 1) casual efficiency as justifying logics 2) family policy as means to recover family values 3) deunifying the family policy. On the one hand, the characteristics of the family policy discourse in "critical camp": 1) social consensus and academic discussion as justifying logics 2) regarding the family policy as a means of gender equality and strategical point of welfare state expansion. The discourse of family and family policy, especially 'Strong Family Discourse" resulted in conjugation of nationalism and neoliberalism.

• Progress in Superconductivity
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• v.6 no.1
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• pp.13-18
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• 2004

High-.ate in-situ$ YBa_2$Cu$Cu_3$$O_{7-x}$ (YBCO) film growth was demonstrated by means of the electron beam co-evaporation. Even though our oxygen pressure is low, ∼$5 ${\times}$10^{-5}$ Torr, we can synthesize as-grown superconducting YBCO films at a deposition rate of around 10 nm/s. Relatively high temperatures of around 90$0^{\circ}C$ was necessary in this process so far, and it suggests that this temperature at a given oxygen activity allows a Ba-Cu-O liquid formation along with an YBCO epitaxy. Local critical current density shows a clear correlation with local resistivity. Homogeneous transport properties with a large critical current density ($4 ∼ 5 MA/\textrm{cm}^2$ at 77K, 0T) are observed in top faulted region while it is found that the bottom part carries little supercurrent with a large local resistivity. Therefore, it is possible that thickness dependence of critical current density is closely related with a topological variation of good superconducting paths and/or grains in the film bodies. The information derived from it may be useful in the characterization and optimization of superconducting films for electrical power and other applications.

• Korean Management Science Review
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• v.23 no.1
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• pp.1-19
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• 2006

This study investigates the critical success factors for the promotion of IT industry in region and suggests some directions for operations strategy of them. This study based on the critical success factors, and we suggest followings : (1) start-ups support, (2) technology support, (3) management support, (4) law/institutional support. We suggested the strategy which based on critical success factors for successful operations of IT industry. This strategy suggested by AHP(Analytic Hierarchy Process) results and was evaluated by the three groups(IT firms, local government official worker, professor) which have an influence on IT policy. We suggested the priority of policy by AHP technique for successful development of IT industry. As a results, centralization of supporting facilities was perceived as the most important policy by three groups(IT firms, local government official worker, professor). This research contributes to assist planners and policy-makers in supporting IT industry by providing useful information about the suggested strategy, and by suggesting the effective means to assist the IT industry. Also, results of our research will be suggested as a priority of developing policy to assist successful IT industry.

• Journal of Korean Academy of Nursing Administration
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• v.16 no.2
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• pp.190-197
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• 2010

Purpose: The purpose of this study was to investigate factors which influence freshmen nursing students' problem solving abilities. Method: The data were collected from 119 students by means of self-reported questionnaires measuring problem solving abilities, critical thinking disposition, and self-directed learning, on March 7th and 11th, 2010. Result: For problem solving ability categories, the level of problem discovery was the highest followed by solution plan, problem definition, solution evaluation and solution implementation. The influencing factors on problem solving abilities of nursing students were critical thinking disposition, self-directed learning and gender. Conclusion: Using the results of this study as a foundation, nursing education curriculum should be comprised of critical thinking skills and self-directed skills for the improvement of nursing students' problem solving abilities. It is also recommended that further studies be conducted in order to investigate comprehensive curriculum designs that allow for maximum accumulation of these proficiencies.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.1
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• pp.51-56
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• 1989

This study was performed to investigate the effect of defect on fatigue strength under the stress of rotary bending. The specimens were made of low carbon steel having artificial microholes, namely, single micro-hole and two adjacent micro-holes as natural defects, and the effects of the diameter of hole and the distance between the holes on fatigue strength have been investigated. The obtained result can be summarized as follows: 1, The critical defect means the largest size of defect that does not affect fatigue limit, and correspondes to the size of defect leading to final fracture under fatigue limit of smooth specimen. The size of defect which has an effect on fatigue limit is larger than that of critical defect. 2, The defect larger than the critical defect affects fatigue strength for as a kind of size effect, and the physical meaning of size effect of defect is considered same as the one of notch effect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.334-339
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• 2002

In this report, numerical investigations have demonstrated, that the displacement underneath a moving loading reach a maximum value, if the speed of the load is equal to propagation velocity of the maximum wave. The load speed for which the maximum displacement occurs is called critical speed. The critical speed divides the velocities in a subcritical and a super-critical region. By means of calculations the dynamic behaviour of the slab track-soil is investigated. For concrete slab track dynamic wheel load are given in dependence of relevant excitation mechanismen and speed of the train. These loads can be used for the dimensioning of the track as well as for prognosis of the vibrations at the track and the surrounding soil.

• Structural Engineering and Mechanics
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• v.3 no.4
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• pp.313-324
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• 1995

Flexible cantilever pipes conveying fluids with high velocity are analysed for their dynamic response and stability behaviour. The Young's modulus and mass per unit length of the pipe material have a stochastic distribution. The stochastic fields, that model the fluctuations of Young's modulus and mass density are characterized through their respective means, variances and autocorrelation functions or their equivalent power spectral density functions. The stochastic non self-adjoint partial differential equation is solved for the moments of characteristic values, by treating the point fluctuations to be stochastic perturbations. The second-order statistics of vibration frequencies and mode shapes are obtained. The critical flow velocity is first evaluated using the averaged eigenvalue equation. Through the eigenvalue equation, the statistics of vibration frequencies are transformed to yield critical flow velocity statistics. Expressions for the bounds of eigenvalues are obtained, which in turn yield the corresponding bounds for critical flow velocities.