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

• 대한치과교정학회지
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• 제45권5호
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• pp.245-252
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• 2015

Objective: To assess the labial and lingual alveolar bone thickness in adults with maxillary central incisors of different inclination by cone-beam computed tomography (CBCT). Methods: Ninety maxillary central incisors from 45 patients were divided into three groups based on the maxillary central incisors to palatal plane angle; lingual-inclined, normal, and labial-inclined. Reformatted CBCT images were used to measure the labial and lingual alveolar bone thickness (ABT) at intervals corresponding to every 1/10 of the root length. The sum of labial ABT and lingual ABT at the level of the root apex was used to calculate the total ABT (TABT). The number of teeth exhibiting alveolar fenestration and dehiscence in each group was also tallied. One-way analysis of variance and Tukey's honestly significant difference test were applied for statistical analysis. Results: The labial ABT and TABT values at the root apex in the lingual-inclined group were significantly lower than in the other groups (p < 0.05). Lingual and labial ABT values were very low at the cervical level in the lingual-inclined and normal groups. There was a higher prevalence of alveolar fenestration in the lingual-inclined group. Conclusions: Lingual-inclined maxillary central incisors have less bone support at the level of the root apex and a greater frequency of alveolar bone defects than normal maxillary central incisors. The bone plate at the marginal level is also very thin.

• Structural Engineering and Mechanics
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• 제35권6호
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• pp.677-697
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• 2010

This paper focuses on geometrically non-linear static analysis of a simply supported beam made of hyperelastic material subjected to a non-follower transversal uniformly distributed load. As it is known, the line of action of follower forces is affected by the deformation of the elastic system on which they act and therefore such forces are non-conservative. The material of the beam is assumed as isotropic and hyperelastic. Two types of simply supported beams are considered which have the following boundary conditions: 1) There is a pin at left end and a roller at right end of the beam (pinned-rolled beam). 2) Both ends of the beam are supported by pins (pinned-pinned beam). In this study, finite element model of the beam is constructed by using total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element. The considered highly non-linear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. In order to use the solution procedures of Newton-Raphson type, there is need to linearized equilibrium equations, which can be achieved through the linearization of the principle of virtual work in its continuum form. In the study, the effect of the large deflections and rotations on the displacements and the normal stress and the shear stress distributions through the thickness of the beam is investigated in detail. It is known that in the failure analysis, the most important quantities are the principal normal stresses and the maximum shear stress. Therefore these stresses are investigated in detail. The convergence studies are performed for various numbers of finite elements. The effects of the geometric non-linearity and pinned-pinned and pinned-rolled support conditions on the displacements and on the stresses are investigated. By using a twelve-node quadratic element, the free boundary conditions are satisfied and very good stress diagrams are obtained. Also, some of the results of the total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element are compared with the results of SAP2000 packet program. Numerical results show that geometrical nonlinearity plays very important role in the static responses of the beam.

• 통상정보연구
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• 제15권1호
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• pp.333-356
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• 2013

본 연구는 uTradeHub시스템의 정식운영이 개시된 후 일정한 기간이 경과한 시점에서 uTradeHub시스템 활용실태를 분석하고, 다수의 표본기업들을 선정하여 이들에 대한 설문조사를 통해 우리나라 중소기업들이 uTradeHub시스템을 활용하는데 영향을 미치는 요인이 무엇인지를 파악하고자 한다. 이러한 활용요인과 uTradeHub시스템의 활용수준 및 성과의 인과관계를 검증함으로써 중소기업의 특성에 맞는 글로벌 전자무역의 활용전략과 이를 발전시키기 위한 협력 방안을 제시하는 것이 본 연구의 궁극적인 목적이다. 이러한 연구 목적을 달성하기 위해서 uTradeHub시스템을 이용하고 있는 회원 중소기업들을 대상으로 설문조사를 통해 실증분석을 한 결과 uTradeHub시스템의 활용 요인 중 기업외부요인으로는 산업내 경쟁강도와 거래강도, 기업내부요인으로는 최고경영자의 지원, 정보화 요인으로는 기업의 IT인프라와 정보화 훈련정도 등이 uTradeHub의 활용에 정의 영향을 미치는 것으로 나타났다. 또한 uTradeHub시스템의 활용도는 전자무역의 재무적 성과와 비재무적 성과에 유의한 정의 영향을 미치는 것으로 나타났다.

• 한국기계가공학회지
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• 제20권3호
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• pp.92-99
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• 2021

An automatic transmission, which consists of several decks of planetary gear sets, provides multiple speed and torque ratios by actuating brakes and clutches (mechanical friction components) for connecting central members of the planetary gear sets. The gear set consists of the sun gear, the ring gear, and the carrier supporting multiple planet gears with pin shafts. In designing a new automatic transmission, there are many steps to design and analyze: gears, brakes and clutches, shafts, and other mechanical components. Among them, selecting thrust bearings that not only allow the relative rotation of the central members and other mechanical components but also support axial forces coming from them is important; doing so yields superior driving performance and better fuel efficiency. In selecting thrust bearings, the magnitude of axial forces on them is a critical factor that affects their bearing size and performance; its results are systematically related to the direction of the helical angle of each planetary gear set (a geometric design profile). This research presents the effects of the helical angle direction on the axial forces acting on thrust bearings in an automatic transmission consisting of planetary gear sets. A model transmission was built by analyzing kinematics and power flows and by designing planetary gear sets. The results of the axial forces on thrust bearings were analyzed for all combinations of helix angle directions of the planetary gear sets.

• Steel and Composite Structures
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• 제44권3호
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• pp.437-450
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• 2022

When the vertical load-bearing members in high-rise structures fail locally, the beam-column joints play an important role in the redistribution of the internal forces. In this paper, a static laboratory test of three full-scale flush flange beam-reinforced connections with side and cover plates (CP-FBSP connection) with double half-span steel beams and single L-shaped columns composed of concrete-filled steel tubes (L-CFST columns) was conducted. The influence of the side plate width and cover plate thickness on the progressive collapse resistance of the substructure was thoroughly analyzed. The failure mode, vertical force-displacement curves, strain variation, reaction force of the pin support and development of internal force in the section with the assumed plastic hinge were discussed. Then, through the verified finite element model, the corresponding analyses of the thickness and length of the side plates, the connecting length between the steel beam flange and cover plate, and the vertical-force eccentricity were carried out. The results show that the failure of all the specimens occurred through the cracking of the beam flange or the cover plate, and the beam chord rotations measured by the test were all greater than 0.085 rad. Increasing the length, thickness and width of the side plates slightly reduced the progressive collapse resistance of the substructures. The vertical-force eccentricity along the beam length reduced the progressive collapse resistance of the substructure. An increase in the connecting length between the beam flange and cover plate can significantly improve the progressive collapse resistance of substructures.

• 마이크로전자및패키징학회지
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• 제30권3호
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• pp.88-93
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• 2023

고대역폭 메모리(HBM)에 대한 수요가 증가하고 직경이 더 큰 웨이퍼의 핸들링 기술이 발전함에 따라 본딩 웨이퍼의 두께 균일성에 대해 신뢰성을 확보할 수 있는 측정 방법이 요구되고 있다. 본 연구에서는 300mm 웨이퍼를 대상으로 웨이퍼의 전 영역에 대해 TTV를 측정할 수 있는 모듈을 설계 제직하고, 측정 모듈의 설계를 바탕으로 발생할 수 있는 측정 오차를 분석하였으며, 웨이퍼의 처짐과 척의 기구적 오차를 고려한 모델 해석을 통해 예측된 기울기 값에 따른 측정 오차를 추정하였다. TTV 측정 모듈은 웨이퍼 지지를 위한 센터 척과 리프트 핀을 활용하여 웨이퍼의 전체 영역에 대해 측정이 가능하도록 하였다. 모달 해석을 통해 모듈의 구조적 안정성을 예측하였으며, 구동부와 측정부 모두 100Hz 이상의 강성을 갖는 것을 확인하였다. 설계된 모듈의 측정 오차를 예측한 결과 두께 1,500um의 본딩 웨이퍼를 측정할 경우 예측된 측정 오차는 1.34nm로 나타났다.

• 통상정보연구
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• 제13권3호
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• pp.31-53
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• 2011

본 연구는 중국 중소기업들이 전자무역을 활용하는데 어떤 요인들이 영향을 미치고 전자무역의 경제적 성과에는 어떤 영향을 주는지 실증 분석하는데 중점을 맞추고 있다. 이를 위해 전자무역에 관한 기존 문헌고찰을 통해 전자무역거래의 활용수준 및 성과와 관련하여 영향을 미칠 수 있는 요인들을 크게 기업외부 요인, 기업내부 요인, 관계특성 요인으로 구분하여 연구모형과 가설을 설정한 다음 중국 장강삼각주 소재의 중소기업들을 대상으로 각 요인들이 전자무역 활용 및 성과에 영향을 미치는 정도에 대한 가설들의 유의성을 실증적으로 검증하고자 하였다. 연구 결과 기업외부요인 중에서는 정부유관기관의 지원정도, 기업내부요인 중에서는 CEO의 지원이 전자무역 활용수준에 유의한 영향을 미치는 것으로 나타났으나, 관계특성요인은 전자무역 활용수준에 유의한 영향을 미치지 않는 것으로 나타났다. 그리고 전자무역 활용수준은 전자무역 활용성과에 유의한 영향을 미치는 것으로 나타났다. 이를 토대로 향후 중국 중소기업의 전자무역 활성화를 위한 시사점과 정책방향을 제시하였다.

• 해양환경안전학회지
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• 제24권2호
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• pp.282-287
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• 2018

긴급하거나 광역으로 발생한 해상유류오염사고에는 방제정만으로 대응하기에는 한계가 있어서, 해양경찰청 경비함정도 방제작업에 동원된다. 본 연구에서는 소형 경비함정에 적합한 유흡착장비를 개발하였다. 장비는 고정지지대, 폴대, 슬라이드고정부 3개 부속품으로 구성되어 용접 또는 추가 구조물 설치 없이 소형 경비함정 현측 추락방지봉에 간단하게 토글핀으로 결속하는 방식으로 장착 및 분리가 가능하다. 각 부속품의 무게는 고정지지대 약 9.2 kg, 폴대(2개) 약 6.5 kg, 슬라이드 고정부(4개) 약 3.5 kg이며, 좌 우 $180^{\circ}$로 원활하게 움직이는 길이 3 m의 폴대는 갑판 방향으로 접어서 유흡착재 교체작업을 할 수 있다. 본 장비의 개발로 소형 경비함정에서 유흡착재의 투입 및 수거가 용이한 방법으로 개선되어 보다 효율적인 방제작업이 가능할 것으로 판단된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.269-269
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• 2012

A new ion source has been designed, fabricated, and installed at the NBTS (Neutral Beam Test Stand) at the KAERI (Korea Atomic Energy Research Institute) site. The goalis to provide a 100 keV, 2MW deuterium neutral beam injection as an auxiliary heating of KSTAR (Korea Super Tokamak Advanced Research). To cope with power demand, an ion current of 50 A is required considering the beam power loss and neutralization efficiency. The new ion source consists of a magnetic cusp bucket plasma generator and a set of tetrode accelerators with circular copper apertures. The plasma generator for the new ion source has the same design concept as the modified JAEA multi-cusp plasma generator for the KSTAR prototype ion source. The dimensions of the plasma generator are a cross section of $59{\times}25cm^2$ with a 32.5 cm depth. The anode has azimuthal arrays of Nd-Fe permanent magnets (3.4 kG at surface) in the bucket and an electron dump, which makes 9 cusp lines including the electron dump. The discharge properties were investigated preliminarily to enhance the efficiency of the beam extraction. The discharge of the new ion source was mainly controlled by a constant power mode of operation. The discharge of the plasma generator was initiated by the support of primary electrons emitted from the cathode, consisting of 12 tungsten filaments with a hair-pin type (diameter = 2.0 mm). The arc discharge of the new ion source was achieved easily up to an arc power of 80 kW (80 V/1000 A) with hydrogen gas. The 80 kW capacity seems sufficient for the arc power supply to attain the goal of arc efficiency (beam extracted current/discharge input power = 0.8 A/kW). The accelerator of the new ion source consists of four grids: plasma grid (G1), gradient grid (G2), suppressor grid (G3), and ground grid (G4). Each grid has 280 EA circular apertures. The performance tests of the new ion source accelerator were also finished including accelerator conditioning. A hydrogen ion beam was successfully extracted up to 100 keV /60 A. The optimum perveance is defined where the beam divergence is at a minimum was also investigated experimentally. The optimum hydrogen beam perveance is over $2.3{\mu}P$ at 60 keV, and the beam divergence angle is below $1.0^{\circ}$. Thus, the new ion source is expected to be capable of extracting more than a 5 MW deuterium ion beam power at 100 keV. This ion source can deliver ~2 MW of neutral beam power to KSTAR tokamak plasma for the 2012 campaign.