• Archives of Metallurgy and Materials
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• v.64 no.2
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• pp.571-578
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• 2019

The densification behavior of H13 tool steel powder by dual speed laser scanning strategy have been characterized for selective laser melting process, one of powder bed fusion based metal 3d printing. Under limited given laser power, the laser re-melting increases the relative density and hardness of H13 tool steel with closing pores. The single melt-pool analysis shows that the pores are located on top area of melt pool when the scanning speed is over 400 mm/s while the low scanning speed of 200 mm/s generates pores beneath the melt pool in the form of keyhole mode with the high energy input from the laser. With the second laser scanning, the pores on top area of melt pools are efficiently closed with proper dual combination of scan speed. However pores located beneath the melt pools could not be removed by second laser scanning. When each layer of 3d printing are re-melted, the relative density and hardness are improved for most dual combination of scanning. Among the scan speed combination, the 600 mm/s by 400 mm/s leads to the highest relative density, 99.94 % with hardness of 53.5 HRC. This densification characterization with H13 tool steel laser re-melting can be efficiently applied for tool steel component manufacturing via metal 3d printing.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.182-190
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• 2005

The fiber Raman amplifier(FRA) is a distinctly advantageous technology. Due to its wider, flexible gain bandwidth, and intrinsically lower noise characteristics, FRA has become an indispensable technology of today. Various FRA modeling methods, with different levels of convergence speed and accuracy, have been proposed in order to gain valuable insights for the FRA dynamics and optimum design before real implementation. Still, all these approaches share the common platform of coupled ordinary differential equations(ODE) for the Raman equation set that must be solved along the long length of fiber propagation axis. The ODE platform has classically set the bar for achievable convergence speed, resulting exhaustive calculation efforts. In this work, we propose an alternative, highly efficient framework for FRA analysis. In treating the Raman gain as the perturbation factor in an adiabatic process, we achieved implementation of the algorithm by deriving a recursive relation for the integrals of power inside fiber with the effective length and by constructing a matrix formalism for the solution of the given FRA problem. Finally, by adiabatically turning on the Raman process in the fiber as increasing the order of iterations, the FRA solution can be obtained along the iteration axis for the whole length of fiber rather than along the fiber propagation axis, enabling faster convergence speed, at the equivalent accuracy achievable with the methods based on coupled ODEs. Performance comparison in all co-, counter-, bi-directionally pumped multi-channel FRA shows more than 102 times faster with the convergence speed of the Average power method at the same level of accuracy(relative deviation < 0.03dB).

• 지역과문화
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• v.8 no.3
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• pp.27-48
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• 2021

In recent years, China's tourism performing art in a series of new completion of the project, increase the box office of tourism performing arts industry, higher economic income, at the same time led to the formation of brand of tourism performing arts and has a good reputation, with the regional culture, has a certain role in promoting economic development, including Large scenario experience drama is one of the key projects. Large scenario experience drama is a new form of drama that simulates the space design of real environment and enables the audience to have active experience in visual, auditory, smell, taste, touch and other senses with strong interactivity.Large scenario experience drama are adapted from traditional Chinese culture, regional culture and long-passed stories, and combine high technology such as lighting, sound effects, special effects and 3D effects to make the audience's experience more real.As the first Large scenario experience drama in China, 'You Jian Ping-yao' reflects the profound culture of Shanxi with new forms of expression and creative means, in the form of scene experience and make the audience more intuitive feel the 'Shanxi emotion', 'Shanxi sentiment' and 'Shanxi Morality', carry forward the traditional culture at the same time, also passed the Shanxi ancient and great values, strengthened the drama of China's movie village, impetus the development of the tourism industry in Shanxi, drive the Shanxi region of jingjing, gradually formed a complete industrial chain. However, there are also limitations such as improper plot connection and improper tourist management, which can improve the performance effect through more audience interaction and guidance. Therefore, it can be seen that large-scale situational experience dramas play a great role in promoting the dissemination of traditional culture and values, the development of tourism industry, the formation of regional brand characteristics and economic development. Through these, it can be seen that large-scale situational experience plays have enlightenments such as innovative thinking content, gradually forming an industrial chain closed-loop, and broadening publicity channels for the development of live-action performances.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.233-240
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• 1996

Analyses of the viscous and end effects on electromagnetic (EM) pumps of annular linear induction type for the sodium coolant circulation in Liquid Metal Fast Breeder Reactors have been carried out based on the MHD laminar flow analysis and the electromagnetic field theory. A one-dimensional MHD analysis for the liquid metal flowing through an annular channel has been performed on the basis of a simplified model of equivalent current sheets instead of three-phase currents in the discrete primary windings. The calculations show that the developed pressure difference resulted from electromagnetic and viscous forces in the liquid metal is expressed in terms of the slip, and that the viscous loss effects are negligible compared with electromagnetic driving forces except in the low-slip region where the pumps operate with very high flow velocities comparable with the synchronous velocity of the electromagnetic fields, which is not applicable to the practical EM pumps. A two-dimensional electromagnetic field analysis based on an equivalent current sheet model has found the vector potentials in closed form by means of the Fourier transform method. The resultant magnetic fields and driving forces exerted on the liquid metal reveal that the end effects due to finiteness of the pump length are formidable. In addition, a two-dimensional numerical analysis for vector potentials has been performed by the SOR iterative method on a realistic EM pump model with discretely-distributed currents in the primary windings. The numerical computations for the distributions of magnetic fields and developed pressure differences along the pump axial length also show considerable end effects at both inlet and outlet ends, especially at high flow velocities. Calculations of each magnetic force contribution indicate that the end effects are originated from the magnetic force caused by the induced current ( u x B ) generated by the liquid metal movement across the magnetic field rather than the one (E) produced by externally applied magnetic fields by three-phase winding currents. It is concluded that since the influences of the end effects in addition to viscous losses are extensive particularly in high-velocity operations of the EM pumps, it is necessary to find ways to suppress them, such as proper selection of the pump parameters and compensation of the end effects.

• Convergence Security Journal
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• v.17 no.2
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• pp.173-183
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• 2017

This study is for presenting the factors about success attribution that fit the korean security service conditions and developing the actual analysis of measurement tools by investigating the success factors of the security service agents. To this end, conducted a meeting from the fully open questionnaire at first, and then formed the semi-structured questionnaire, finally carried out the survey from the closed questionnaire and analyzed data from SPSS 21.0, AMOS 21.0 and developed the measurements. It was conducted from December, 2014 to June, 2015. This survey was conducted of 170 security guards after the verification of the content validity though the pilot survey and presented the success attribution factors and standards on the basis of the result form this survey. At the first and second analysis process, the success attribution factors of the guards consisted of inner qualities, external qualities, induction factors for inner qualities, and induction factor for external qualities. On analysis of the final data and documents, however, at the third analysis, the success attribution factors of the guards consisted of 'martial arts and physical ability'(4 questions), 'attitudes to work'(3 questions), 'support for the working environment'(3 questions), 'organized business skills'(3 questions), 'attitudes to the duty'(3 questions), and 'coping with crises(2 questions).

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.567-575
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• 2012

A research was conducted to develop a 2-D nonlinear Galerkin finite element analysis of reinforced concrete structures subjected to high temperature with experiments. Algorithms for calculating the closed-form element stiffness for a triangular element with a fully populated material conductance are developed. The validity of the numerical model used in the program is established by comparing the prediction from the computer program with results from full-scale fire resistance tests. Details of fire resistance experiments carried out on reinforced concrete slabs, together with results, are presented. The results obtained from experimental test indicated in that the proposed numerical model and the implemented codes are accurate and reliable. The changes in thermal parameters are discussed from the point of view of changes of structure and chemical composition due to the high temperature exposure. The proposed numerical model takes into account time-varying thermal loads, convection and radiation affected heat fluctuation, and temperature-dependent material properties. Although, this study considered standard fire scenario for reinforced concrete slabs, other time versus temperature relationship can be easily incorporated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.499-505
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• 2017

In this study, the limit loads calculated by the $m_{\alpha}-tangent$ method based on the linear finite element analysis are compared with the closed form solutions that are proposed by various authors. The objects of the analysis is to select the elbow and the branch pipe which are representative structure of piping system. The applicability of the $m_{\alpha}-tangent$ method are investigated by applying it to cases with various geometries. The internal pressure and the in-plane bending moment are considered and the $m_{\alpha}-tangent$ method is in good agreement with the existing solutions in case of elbows. However, the limit loads calculated by the $m_{\alpha}-tangent$ method for branch junctions do not agree well with the existing solutions and do not show any tendency. The reason is a biased result due to the stress concentration of the discontinuous parts.

• Journal of Physiology & Pathology in Korean Medicine
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• v.35 no.6
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• pp.211-218
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• 2021

In order to increase the clinical value of an identification of patterns according to the eight principles (IPEP) in Korean medicine practice, The research on the Clinical Practice Guideline (CPG) of IPEP should comprehend the situation of clinical usage of IPEP practiced by Korean medicine doctors at first. Google survey form were emailed to Korean Medicine doctors registered in the Association of Korean Medicine on 04/15/2021 and the survey was closed at 04/22/2021. Data of 505 answered cases were analyzed by Frequency analysis, Chi-Square analysis, correlation analysis for understanding differences by groups. Out of 505 respondents, 57.6% have answered that they are using IPEP. It means that 42.4% of KM doctors don't use in the medical practice reversely in spite of fundamental diagnostic theory. The 64.7% respondents of no using IPEP presented their opinion about the theoretical problem that it is difficult to use because the concept of IPEP is ambiguous. And next, the 52.1% of the respondents expressed that there is no objective tools to measure and record the IPEP evidences in actual implementation. And 49.6% of the respondents also suggested that it is hard to trust and use IPEP similar to the previous comment. Even about 50% of the respondents are carrying out diagnosis and treatment using IPEP, it showed that there were several unsolved problems such as lack of understanding and practical tools or objective indicators for diagnosis of IPEP. Through the above results, the concept, usage, measurement requirements with indices and discriminant logic of IPEP were manifested as the main hopes of attending members of Korean medicine in the survey, so the IPEP CPG should make clear about these difficult but necessary assignment in the near future.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.375-381
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• 2021

This study aimed to examine the dilemma of rural China under rapid urbanization process after economic reform, by paying attention to the problem of the order of village community and the expression of individual desires depicted in the film with a rural background. To this end, the narrative analysis, which is suitable for exploring the story structure and expression style of the text, was conducted to examine the community order and ethics, patriarchy and paternity, and the expression of desires of subject. In the film, closed space and villagers, who are disciplined by community customs, local culture, and formality of the rule of manners, are depicted. The film is covered in a form of mystery movie dealing with the deaths of members of the village community. However, the film talks about the rise of the Imaginary desire of subject against the symbolic rules of community order and ethics through the puzzle pieces story according to the perspectives of the characters. In conclusion, through the narrative analysis, it was possible to examine the implications of weakened communal discipline and paternity of the countryside by the rapid urbanization of China, and implications of the lethargy and neurosis of the subjects.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.86-92
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• 2012

Point estimate method has a less accuracy than Monte Carlo simulation that is usually considered as an exact probabilistic method, but this method still remains popular in probability-based reliability assessment in geotechnical and rock engineering, because it significantly reduce the number of sampling points and produces the statistical moments of a performance function in a reasonable accuracy. In the present study, we investigated the accuracy and applicability of point estimate methods proposed by Rosenblueth and Zhou & Nowak by comparing the results of these two methods with those of Monte Carlo simulations. The comparison was carried out for the problem of a lined circular tunnel in an elastic medium where an closed-form analytical solution is given. The comparison results showed that despite the non-linearity of the analytical solution, the statistical moments calculated by the point estimate methods and the Monte Carlo simulations agreed well with an average error of roughly 1-2%. This average error demonstrates the applicability of the two point estimate methods for the probabilistic reliability assessment of underground structures in combination with numerical analysis.