• Journal of Power Electronics
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• v.18 no.5
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• pp.1545-1554
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• 2018

This paper proposes a modified control strategy to improve the performance of three-phase four-leg shunt active power filters (APFs) for the compensation of three phase unbalanced loads. Unbalanced current cannot be obtained accurately by a harmonic detector due to the lower frequency. The proposed control strategy eliminates conventional harmonic detectors by directly regulating the source current. Therefore, the computational complexity is greatly reduced and the performance of the APF is improved. A mathematic model has been developed based on the source currents. The corresponding controllers have been designed based on the sinusoidal internal model principle. The proposed control strategy can guarantee excellent compensation performance and stable operation after an extreme disturbance such as a short circuit fault. In addition, the proposed technique can selectively compensate specific harmonics. A 50kVA prototype APF is implemented in the laboratory to validate the feasibility and performance of the proposed control strategy.

• Computers and Concrete
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• v.18 no.5
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• pp.1041-1051
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• 2016

In this study, the construction of a reinforced concrete bridge pier was analyzed from durability point of view. The goal of the study is to analyze the crack iniation condition due to construction and present some recommendations for construction conditions of the reinforced concrete bridge pier. The bridge is located at the western port area of Shenzhen, where the climate is high temperature and humidity. To control the cracking of concrete, a construction simulation was carried out for a heat transfer problem as well as a thermal stress problem. A shrinkage model for heat produced due to cement hydration and a Burger constitutive model to simulate the creep effect are used. The modelling based on Femmasse(C) is verified by comparing with the testing results of a real underground abutment. For the bridge pier, the temperature and stress distribution, as well as their evolution with time are shown. To simulate the construction condition, four initial concrete temperatures ($5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, $20^{\circ}C$) and three demoulding time tips (48h, 72h, 96h) are investigated. From the results, it is concluded that a high initial concrete temperature could result in a high extreme internal temperature, which causes the early peak temperature and the larger principle stresses. The demoulding time seems to be less important for the chosen study cases. Currently used 72 hours in the construction practice may be a reasonable choice.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.561-566
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• 2008

The reciprocating compressor is widely used in the industry field, because it has simple principle and high efficiency. In this work, in order to improve design of discharge passage line in hydrogen compression system Numerical analysis was conducted. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including velocity, pressure and turbulence kinetic energy distribution of hydrogen gas going out from the cylinder to discharge-path line are presented in this paper. Discharge-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows velocity, pressure and turbulent kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement might be done.

• Convergence Security Journal
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• v.22 no.3
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• pp.3-11
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• 2022

With increasingly sophisticated cyber threats, accelerating cloud adoption, and the adoption of remote and hybrid work environments due to the COVID-19 pandemic, the traditional security model, in which many businesses implicitly trust everything within their boundaries, is changing without boundaries, allowing data and users The concept of zero trust is getting more and more attention as the fact that it is not suitable for today's increasingly decentralized environment has been highlighted. Zero Trust is a cyber security model on the premise that 'no one trusts'. In principle, there is no safe area or user in the entire system, and internal users are also verified. is a way As telecommuting becomes commonplace due to the COVID-19 pandemic, and existing cyber security measures are facing limitations, Zero Trust technology is drawing more attention. Accordingly, it is expected that the Korean government will also check the status of acceptability of the domestic public and private sectors and tasks that need improvement when introducing Zero Trust with reference to the NIST standard. In this paper, the basic principles, philosophy, and considerations of Zero Trust and Zero Trust are explained, and practical basic measures to strengthen security by combining Zero Trust technology are presented.

• 기호학연구
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• no.54
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• pp.205-224
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• 2018

This research is to investigate the way to combine Peirce's typology of signs with architectural design. A new diagram is suggested to ensure the continuity of Peirce's typology, by rearranging and reconstructing the well known inverted triangle diagram showing the structure of the typology. The new diagram is easier to understand the organization of the typology, by showing the linkages between sign types and their relationships with other types. A way to adapt the new diagram to architectural design for the purpose of representing typology as well as ensuring model growth as semiotic model for architectural design model. The new model is organized of three sign clusters, sinsign cluster, legisign cluster, and symbolic cluster. They are interrelated through successive inclusion and case inclustion. The new model is organized of threefold layers. The first layer is internal structure of each cluster. The second is interrelation between cluster. The third is mediation of symbolic cluster between sinsign cluster and legisign cluster. This paper investigate and demonstrate the possibility of adaptation of the new model in architectural design. It has been argued that the theoretical basis of sign typology is adaptable to architectural design by principle. More future research issues are discussed.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.687-694
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• 2014

This study established a displacement ductility ratio model for ductile design for the boundary element of shear walls. To determine the curvature distribution along the member length and displacement at the free end of the member, the distributions of strains and internal forces along the shear wall section depth were idealized based on the Bernoulli's principle, strain compatibility condition, and equilibrium condition of forces. The confinement effect at the boundary element, provided by transverse reinforcement, was calculated using the stress-strain relationship of confined concrete proposed by Razvi and Saatcioglu. The curvatures corresponding to the initial yielding moment and 80% of the ultimate state after the peak strength were then conversed into displacement values based on the concept of equivalent hinge length. The derived displacement ductility ratio model was simplified by the regression approach using the comprehensive analytical data obtained from the parametric study. The proposed model is in good agreement with test results, indicating that the mean and standard deviation of the ratios between predictions and experiments are 1.05 and 0.19, respectively. Overall, the proposed model is expected to be available for determining the transverse reinforcement ratio at the boundary element for a targeted displacement ductility ratio.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.3
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• pp.148-156
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• 2005

The purpose of this paper is to propose an approach to design a robust servo controller based on the mixed $H_2/H_{\infty}$ theory, and confirm its validity by applying to a benchmark problem. First, the existing $H_{\infty}$ servo problem is modified to a structure for the mixed $H_2/H_{\infty}$ control problem by virtue of the internal model principle. By making use of proposed structure, we can divide specifications required in the robust servo system design into $H_2$ and $H_{\infty}$ performance criteria, respectively. It is shown that the proposed design approach is quite effective through an application to a three inertia benchmark problem.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.257-274
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• 2015

The purpose of the current study was to validate Fetzer Institute & National Institute on Aging Working Group[NIA](1999)'s Brief-Multidimensional Measure of Religiousness/Spirituality Scale (BMMRS) in Korean adults. The Korean version of BMMRS, Spiritual Well-Being Scale(SWS), Korean Sprituality Scale(KSS), Penn State Worry Questionnaire(PSWQ), and Intolerance of uncertainty Scale(IUS) were administered to the 286 students and community samples. A principle axis factoring analysis with direct oblimin rotation and Kaiser normalization identified a six-factor solution accounting for 66.24% of the variance in scores, labeled as: positive spiritual experience, negative spiritual experience, forgiveness, religious practices, negative congregational support, and positive congregational support. Confirmatory factor analysis results showed that 6 factor model of BMMRS have a good fitness. Also, the internal consistency(.64~.97) and the test-retest reliablity was adequate.(.72~.88) Korean version of BMMRS has adequate psychometric characteristics so it can be used to verify the effects of various compassion-related psychotherapeutic approaches.

• The Journal of Korean Medicine
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• v.17 no.1 s.31
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• pp.447-464
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• 1996

Hyperemesis gravidarum is one of the most common symptom in the early pregnancy and if it cause severe malnutrition by means of heavy vomiting as a basic sign of disease of pregnant syndrome, appropriate treatments are necessary. In the clinics the methods of treatment of hyperemesis gravidarum include herb-medication usually. But herb-medication therapy is rather difficult because during pregnancy it may cause vomiting by the smell and taste of herbs. So the author investigated the literatures referred to the external treatments of hyperemesis gravidarum excluding herb-medication and the results obtained here were as follows. 1. The external methods of treatment of hyperemesis gravidarum are various and include moxibustion, the method of applying drug at the umbilicus, ear-acupuncture method, pressure massage therapy, naso-spray method, acupoint injection, intervenous injection 2. Among the external methods of treatment of hyperemesis gravidarum , the method of applying drug at the umbilicus is most variable and almost all prescriptions use Zingiber officinalis Rose, characteristically. 3. Ear-pressure massage method to treat the hyperemesis gravidarum uses the car-acupoints of Gan, We, Shin-mun, Gyo-gam. 4. Among the external methods of treatment of hyperemesis gravidarum , moxibustion, pressure massage, and acupoint injection select frequently Nae-gwan(PC6), Chok-samni(ST36) and Chung-wan(CV12). 5. In the both the internal and external methods of treatment of hyperemesis gravidarum one have to differentiate syndromes in the viewpoint of oriental medicine and treat with the principls of treatment and prescriptions which are fit to each differentiation model under the principle of regulating the stomach and relieving vomiting.

• Journal of Practical Engineering Education
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• v.14 no.2
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• pp.413-423
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• 2022

The purpose of this study is to analyze the role of the job competency assessor who assess achievement of job performance ability based on NCS (educational training, qualifications, field experience, etc.) through competency assessment. For this purpose, job analysis including development and verification of the job model and selection of core task are conducted. As a result, main duties of the job competency assessor are to understand the NCS based assessment principle, establish an assessment plan, design and develop assessment tools, assess competence, provide feedback and re-assessment, record and manage assessment result, verify the internal assessment result, establish the RPL (recognition of prior learning) plan, implement the RPL and verify the RPL assessment result, and 48 task are derived. In addition, a total of 21 core tasks are derived based on the threshold value multiplied by the importance and difficulty of the task for each duty. Based on this, implications for job analysis of the job competency assessor are presented.