• 전력전자학회논문지
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• 제25권6호
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• pp.459-468
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• 2020

The pole interaction of the line-commutated converter high-voltage direct current (HVDC) is analyzed, and a practical solution that uses a surge arrester is proposed. Jeju HVDC No. 2 is a double-monopole HVDC link that has a rated power capacity of 2 × 200 MW and was commissioned in 2012. During normal operation, Jeju HVDC No. 2 is operated in the bipolar mode to minimize the loss caused by the dedicated metallic return. However, when one pole of the inverter valve is bypassed, a commutation failure can occur in the other pole. This phenomenon is called pole interaction in this work. This pole interaction interrupts the HVDC power transfer for almost 2 s and may affect the stability of the power system. This research proposes the installation of a surge arrester at the inverter neutral, which can be an effective and practical solution for pole interaction. The HVDC system is analyzed, and the residual voltage of the surge arrester is determined. Detailed simulation using PSCAD/EMTDC demonstrates that the proposed method eliminates the pole interaction of the bipolar-operated HVDC.

• 한국융합학회논문지
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• 제11권3호
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• pp.45-52
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• 2020

본 연구에서는 현존하고 있는 잠금 해제 방식에서 보이는 문제점으로부터 출발해 보안성 및 사용성 측면에서 개선된 블라인드 인터랙션을 적용한 상대적 위치 기반 패턴 잠금 해제 방식을 제안하고 이론적 타당성을 고찰했다. 기존 숫자암호 잠금 해제 방식과 패턴 그리기 잠금 해제 방식과의 차이를 실험을 통해 확인하고 실용적 가치를 평가했다. 상대적 위치 패턴은 숫자 암호 보다 쉽게 기억되고 그리기 패턴과 비슷한 정도의 학습 용이성을 보여 주었고 타 방식에 비해 훔쳐보기 공격에 안전한 결과를 얻었다. 생체신호를 센싱 할 센싱 모듈을 사용할 필요 없이 터치스크린의 기본기능만으로 실현 가능하기에 적은 원가로 제작할 수 있다. 시각적 요소가 필요 없는 방식이기에 시각 장애인과 같은 특수 사용자들도 불편함 없이 사용할 수 있기에 실용적 가치도 상대적으로 높다.

• The Korean Journal of Physiology and Pharmacology
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• 제25권6호
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• pp.545-553
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• 2021

Fixed-dose combinations development requires pharmacokinetic drugdrug interaction (DDI) studies between active ingredients. For some drugs, pharmacokinetic properties such as long half-life or delayed distribution, make it difficult to conduct such clinical trials and to estimate the exact magnitude of DDI. In this study, the conventional (non-compartmental analysis and bioequivalence [BE]) and model-based analyses were compared for their performance to evaluate DDI using amlodipine as an example. Raw data without DDI or simulated data using pharmacokinetic models were compared to the data obtained after concomitant administration. Regardless of the methodology, all the results fell within the classical BE limit. It was shown that the model-based approach may be valid as the conventional approach and reduce the possibility of DDI overestimation. Several advantages (i.e., quantitative changes in parameters and precision of confidence interval) of the model-based approach were demonstrated, and possible application methods were proposed. Therefore, it is expected that the model-based analysis is appropriately utilized according to the situation and purpose.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.132-139
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• 2000

This paper presents a new hybrid approach for nonlinear dynamic analysis of the soil-structure interaction system in the time domain. It employs, in a practical manner, a linear SSI program and a general-purpose nonlinear finite element program. In order to demonstrate the validity and applicability of the proposed method, seismic response analyses are carried out for a free-field problem and a 2-D subway station. The results indicate that the proposed methodology gives reasonable solution for the linear/nonlinear SSI problem utilizing a general-purpose finite element program. Some further studies will endorse the applicability of the method to various soil-structure interaction problems.

• 한국자기공명학회논문지
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• 제25권1호
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• pp.1-7
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• 2021

Employing of 13C stable-isotopes in NMR metabolomics can give unique splitting patterns and coupling constants information originated from 13C-13C coupling interaction that provide an important structural information regarding the cellular metabolic process. But it has been known that an undesirable signal distortion in 2D heteronuclear correlation study, due to 13C-13C interaction, hampers an analysis of the coupling information. Recently, we proposed J-scaled distortion-free heteronuclear single-quantum coherence (HSQC) sequence which provides a distortion-free 13C-13C coupling information with a selective resolution enhancement of JCC splitting. In this paper, we dicuss theoretical aspect and practical feature of J-scaled HSQC pulse sequence. The conceptual explanation of orgin of the signal distortion by 13C-13C coupling interaction and design of J-scaled HSQC through exemplified results are provided in brief.

• 한국가정과교육학회지
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• 제33권1호
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• pp.1-16
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• 2021

본 연구의 목적은 원격학습 환경에서 실천적 추론 과정에 대한 중학생의 요구도를 조사하고, 학습자의 개인적 특성과 교사 상호작용, 학생 간 상호작용에 따라 요구도의 차이를 검증하며, 교사와의 상호작용, 학습자의 자발적 참여도, 실천적 추론 과정에 대한 반영도와의 관계를 알아보는 것이다. 이를 위해 경기, 대전, 충북, 세종 등 7개 학교의 중학생 1,842명을 대상으로 하여 실천적 추론 과정의 질문 내용에 대한 중요도와 현재 원격수업의 반영도를 온라인으로 설문 조사하였다. 이 중 1,095명이 답한 결과로 요구도를 산출하고, 기술통계, 독립표본 t-검정, 일원배치 분산분석, 경로분석을 하였다. 연구 결과 첫째, 원격학습 환경에서 가정교과의 실천적 추론 과정에 대해 중학생들은 중요도 평균이 3.76으로 실천적 추론 과정이 중요하다고 인식하였다. 가정교과 원격수업에서 요구도의 우선순위를 The locus for focus 모델로 확인한 결과, 문제의 가치와 중요성, 문제의 상황과 관련된 고정관념, 해결방안의 파급효과, 정보의 신뢰성, 실천을 어렵게 하는 요소의 극복 방안, 실천내용을 반성하게 하는 질문이 우선적으로 고려되어야 하는 것으로 나타났다. 둘째, 중학생의 개인적 특성, 교사와의 상호작용, 학생 간 상호작용에 따라 요구도에 차이가 있는지 검증한 결과, 성별, 원격수업의 자발적 참여도에 따라서 유의한 차이가 없었다. 반면에 교사와의 상호작용, 학생 간의 상호작용은 실천적 추론 과정의 요구도에 유의한 차이를 보이는 것으로 나타났다. 셋째, 원격학습 환경에서 학생의 자발적 참여도와 교사와의 상호작용은 반영도에 정(+)적으로 유의한 영향을 미치는 것으로 분석되었고, 반영도는 요구도에 부(-)적으로 유의한 영향을 미치는 것으로 분석되었다. 원격학습 환경에서 실천적 추론 수업을 실행할 때 비판적 질문을 통해서 학습자로 하여금 행동을 반성하고 깨달음을 얻을 수 있는 질문을 우선적으로 고려할 필요가 있다. 또한, 교사, 학생 간의 상호작용과 학생의 자발적 참여도를 높이기 위한 방안을 탐색하여 실행할 필요가 있다.

• Structural Engineering and Mechanics
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• 제1권1호
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• pp.17-30
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• 1993

A practical multi-spring model is proposed for a nonlinear analysis of reinforced concrete members, especially columns, taking into account the interaction of axial load and bi-directional bending moment. The parameters of the model are determined on the basis of material properties and section geometry. The axial force-moment interaction curve of reinforced concrete sections predicted by the model was shown to agree well with those obtained by the flexural analysis utilizing realistic stress-strain relations of materials. The reliability of the model was also examined with respect to the test of reinforced concrete columns subjected to varying axial load and bi-directional lateral load reversals. The analytical results agreed well with the experiment.

• 수산해양기술연구
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• 제40권1호
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• pp.73-77
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• 2004

It is well known that the hydrodynamic interaction forces between ship and bank wall affect ship manoeuvring motions. In this paper, the calculation method based on the slender body theory for estimation of the hydrodynamic interaction forces between ship and bank wall is investigated. The numerical simulations on hydrodynamic interaction force acting on a ship in the proximity of bank wall are carried out by using this theoretical method. The theoretical method used in this paper will be useful for practical prediction of ship manoeuvrability at the initial stage of design, for discussion of marine traffic control system and for automatic control system of ship in confined waterways.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2001년도 봄 학술발표회 논문집
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• pp.363-370
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• 2001

A computationally efficient algorithm to analyze a group pile behavior is proposed by consideration of both soil-pile and pile-cap interactions. Using toad transfer method the nonlinear characteristics of the soil-pile interaction for a single pile is modeled by piecewise linear soil springs (p-y, t-z, and q-z curves). Beam-column method, one of the most practical approaches, is used for numerical modeling of the soil-pile system. In addition to the group effect resulting from the soil-pile-soil interaction, for a more realistic analysis it is essential to consider the effect of pile-cap interaction including geometric configuration of the piles in a group and conectivity conditions between piles and the cap. This paper mainly focuses on the pile-cap interaction and the development of a rational numerical procedure of its incorporation with the beam-column method.

• Wind and Structures
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• 제5권2_3_4호
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• pp.101-114
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• 2002

Both a Finite Volume and a Discrete Vortex technique to solve the unsteady Navier-Stokes equations have been employed to study the air flow around long-span bridge decks. The implementation and calibration of both methods is described alongside a quasi-3D extension added to the DVM solver. Applications to the wind engineering of bridge decks include flow simulations at different angles of attack, calculation of aerodynamic derivatives and fluid-structure interaction analyses. These are being presented and their specific features described. If a numerical method shall be employed in a practical design environment, it is judged not only by its accuracy but also by factors like versatility, computational cost and ease of use. Conclusions are drawn from the analyses to address the question of whether computer simulations can be practical design tools for the wind engineering of bridge decks.