• 한국수학교육학회지시리즈E:수학교육논문집
• /
• 제34권3호
• /
• pp.235-256
• /
• 2020

본 연구는 예비수학교사의 교육실습 현장수행 역량을 높이기 위해, 디자인 사고 프로세스를 활용한 대학수업과 학교 현장의 교육실습 연계형 프로그램을 운영하고 참여한 예비수학교사들의 경험을 분석하는 데 목적을 두었다. 이를 위해, 2019학년도 1학기 교육실습 대상자인 예비수학교사 8명이 참여한 대학 전공 수업에 디자인 사고 5단계 프로세스를 적용한 후, 참여자 집단 및 개별 면담 자료와 디자인 사고 활동 결과물 등 질적 자료를 수집 분석하였다. 자료 분석에 따른 연구결과는 다음과 같다. 첫째, 대학수업에서의 디자인 사고 1~4단계를 통해 참여자들의 인식은, 초기에 공감 단계의 혼돈과 막연함에서 시작하였으나 시간의 흐름에 따라 프로그램 활동에 대해 보다 적극적인 변화를 보였다. 둘째, 교육실습 중, 디자인 사고의 5번째 단계인 평가단계에서는, 참여 예비수학교사들이 이전단계에서 생성한 프로토타입의 적용성을 확인하는 활동을 적극적으로 수행하였다. 다만, 일부 현장의 허용적이지 않은 상황으로 인해 프로토타입의 적용에 어려움을 가진 사례도 있었다. 셋째, 교육실습 후, 대학수업에서의 평가 및 성찰 과정에서 참여자들은 디자인 사고 활동의 필요성에 긍정적으로 공감하였다. 끝으로, 대학수업과 학교현장의 교육실습 간 융통성 있는 연결을 위해 두 영역의 긴밀한 연계가 전제될 필요가 있음이 확인되었다.

• Steel and Composite Structures
• /
• 제30권2호
• /
• pp.81-96
• /
• 2019

The behavior of a new Three-Tube Buckling-Restrained Brace (TTBRB) with circumference pre-stress (${\sigma}_{{\theta},pre}$) in core tube are investigated through a verified finite element model. The TTBRB is composed of one core tube and two restraining tubes. The core tube is in the middle to provide the axial stiffness, to carry the axial load and to dissipate the earthquake energy. The two restraining tubes are at inside and outside of the core tube, respectively, to restrain the global and local buckling of the core tube. Based on the yield criteria of fringe fiber, a design method for restraining tubes is proposed. The applicability of the proposed design equations are verified by TTBRBs with different radius-thickness ratios, with different gap widths between core tube and restraining tubs, and with different levels of ${\sigma}_{{\theta},pre}$. The outer and inner tubes will restrain the deformation of the core tube in radius direction, which causes circumference stress (${\sigma}_{\theta}$) in the core tube. Together with the ${\sigma}_{{\theta},pre}$ in the core tube that is applied through interference fit of the three tubes, the yield strength of the core tube in the axial direction is improved from 160 MPa to 235 MPa. Effects of gap width between the core tube and restraining tubes, and ${\sigma}_{{\theta},pre}$ on hysteretic behavior of TTBRBs are presented. Analysis results showed that the gap width and the ${\sigma}_{{\theta},pre}$ can significantly affect the hysteretic behavior of a TTBRB.

• Nuclear Engineering and Technology
• /
• 제45권6호
• /
• pp.721-730
• /
• 2013

Within the framework of the ASTRID project, core design studies are being conducted by the CEA with support from AREVA and EDF. The pre-conceptual design studies are being conducted in accordance with the GEN IV reactor objectives, particularly in terms of improving safety. This involves limiting the consequences of 1) a hypothetical control rod withdrawal accident (by minimizing the core reactivity loss during the irradiation cycle), and 2) an hypothetical loss-of-flow accident (by reducing the sodium void worth). Two types of cores are being studied for the ASTRID project. The first is based on a 'large pin/small spacing wire' concept derived from the SFR V2b, while the other is based on an innovative CFV design. A distinctive feature of the CFV core is its negative sodium void worth. In 2011, the evaluation of a preliminary version (v1) of this CFV core for ASTRID underlined its potential capacity to improve the prevention of severe accidents. An improved version of the ASTRID CFV core (v2) was proposed in 2012 to comply with all the control rod withdrawal criteria, while increasing safety margins for all unprotected-loss-of-flow (ULOF) transients and improving the general design. This paper describes the CFV v2 design options and reports on the progress of the studies at the end of pre-conceptual design phase 1 concerning: - Core performance, - Intrinsic behavior during unprotected transients, - Simulation of severe accident scenarios, - Qualification requirements. The paper also specifies the open options for the materials, sub-assemblies, absorbers, and core monitoring that will continue to be studied during the conceptual design phase.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.284-288
• /
• 2015

Recently, the mandate on utilizing BIM implemented by public institutions of many countries has great impact on the significantly increasing practices of BIM. The improvement of work efficiency and productivity, which is occurred by BIM adoption, depends on the consistency and accuracy of data. To maximize the benefit of BIM, the interests in BIM data quality have been enlarging all over the world. The BIM data quality pre-check, which is conducted by designer in the design phase, offers opportunities for quality improvement by continuously assessing BIM data. However, BIM quality pre-check is being conducted under arbitrary interpretation of users because of the absence of specific review factors and assessment methods for checking BIM quality. The purpose of this study is to establish an automated BIM quality pre-checking system to improve BIM design quality effectively and efficiently. It could be expected to meet the owner's requirements and to minimize the cost and time occurred additionally from revising and reproducing data by constructing consistency and accuracy of it.

• 전자공학회논문지
• /
• 제50권1호
• /
• pp.131-136
• /
• 2013

칩 적층기술의 발달로 TSV(Through Silicon Via) 기반 3D IC가 개발되었다. 3D IC의 높은 신뢰성과 수율을 얻기 위해서는 pre-bond 와 post-bond 수준에서 다양한 TSV 테스트가 필수적이다. 본 논문에서는 pre-bond 다이의 TSV 연결부에서 발생하는 미세한 고장과 post-bond 적층된 3D IC의 TSV 연결선에서 발생하는 다양한 고장을 테스트할 수 있는 설계기술을 소개한다. IEEE 1500 표준 기반의 래퍼셀을 보완하여 TSV 기반 3D IC pre-bond 및 post-bond의 at speed test를 통하여 known-good-die와 무결점의 3D IC를 제작하고자 한다.

• Journal of electromagnetic engineering and science
• /
• 제9권2호
• /
• pp.71-77
• /
• 2009

OFDM(Orthogonal Frequency Division Multiplexing) signals sutler serious nonlinear distortion in the nonlinear HPA(High Power Amplifier) because of high PAPR(Peak Average Power Ratio). Nonlinear distortion can be improved by a pre-distorter, but this pre-distorter is insufficient when the PAPR is very high in an OPFDM system. In this paper, a DFT(Discrete Fourier Transform) transform technique is introduced for PAPR reduction. It is especially important to consider the memory effect of HPA for more precise predistortion. Therefore, in this paper, we consider two models, the TWTA(Traveling-Wave Tube Amplifier) model of Saleh without a memory effect and the HPA memory polynomial model that has a memory effect. We design a pre-distorter and an adaptive pre-distorter that uses the NLMS(Normalized Least Mean Square) algorithm for the compensation of this nonlinear distortion. Without the consideration of a memory effect, the system performance would be degraded, even if the pre-distorter is used for the compensation of the nonlinear distortion. From the simulation results, we can confirm that the proposed system shows an improvement in performance.

• 화약ㆍ발파
• /
• 제20권3호
• /
• pp.59-71
• /
• 2002

The points of this design case are the planning and excavation method of a new double-tracked railroad tunnel which is approx. 11∼22 meters apart from existing single-tracked railroad tunnel. For the optimum excavation method some needs are required in design stage, such as the reduction of noise and vibration, public resentment, damage of buildings and construction costs. Hence the estimation and application of allowable noise and vibration criterion is important. The ground coefficient (K, n) of this site is determined by field trial blasting. The excavation method is chosen to satisfy the allowable noise and vibration criterion. In addition, in order to ensure the stability of existing single-tracked railroad tunnel, the instrumentation of maintenance level is accompanied during the construction stage. As a result of this design condition, central diaphragm excavation with line drilling and pre-large hole boring blasting is applied to the area within 15 meters apart from existing tunnel. And above 15 meters apart, pre-large hole boring blasting is designed.

• Computers and Concrete
• /
• 제11권1호
• /
• pp.75-91
• /
• 2013

In this paper, a new approach for cable layout design of pre-stressed concrete slabs is presented. To account the cable profile accurately, it is modelled by B-spline. Using the convex hull property of the B-spline, an efficient algorithm has been developed to obtain the cable layout for pre-stressed concrete slabs. For finite element computations, tendon and concrete are modelled by 3 noded bar and 20 noded brick elements respectively. The cable concrete interactions are precisely accounted using vector calculus formulae. Using the proposed technique a two way prestressed concrete slab has been successfully designed considering several design criteria.

• 한국생산제조학회지
• /
• 제25권1호
• /
• pp.89-95
• /
• 2016

This study investigated the design factors of the opening area in order to consider the kinematic stability of a valve plate, conducting an analysis of the reduction effects of pressure pulsation and flow ripple depending on the design factors, using the $SimulationX^{(R)}$ (Germany) hydraulic analysis program. Further, we performed a structure analysis to confirm the kinematic stability of the valve plate in a swash plate type piston pump, and analyzed the effects of pulsation on a 1-step V-type notch, 2-step V-type notch, and 2-step U-type notch to determine the effects of pulsation reduction. Finally, we show the effectiveness of our proposed design of the pre-compression sections on a valve plate in terms of low pulsation by using the hydraulic analysis program, $SimulationX^{(R)}$.

• 대한조선학회논문집
• /
• 제50권3호
• /
• pp.145-152
• /
• 2013

Recently, with oil price jumping and environmental issues, Green ship is paid deep attention to by ship owner, operator, builder, class and government. Fuel efficiency and reduction of $CO_2$ emissions are expected to have a strong influence on the design and operation of merchant ships. Many ship owners and operators are seeking the more economic method by the best operating route and the application of reliable and effective energy saving devices. With the Energy Efficiency Design Index (EEDI) in 2013 attention will more than ever be focused at achieving maximum fuel economy in the hydrodynamic design of hull forms, their appendages and propellers. IMO requirements for $CO_2$ emission for ships will now be implemented for vessels ordered from 1st January 2013. So far, a lot of new idea and patents have been proposed, tested, claimed and applied for various kinds of ship type. This paper shows numerical and experimental work related to a study on a energy saving devices particularly for fuller ship such as merchant vessel of Tanker and Bulker. From the bare hull wake measurements, typical upper/lower asymmetry of hull wake at the propeller disk was found. The pre-swirl duct have been designed and reviewed to recover the loss of propeller running in that condition. The general function of the pre-swirl duct was set to work against this asymmetry of wake and generate pre-swirled flow into the propeller against the propeller rotating direction.