• Composites Research
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• 제37권1호
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• pp.7-14
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• 2024

이중 롤러는 Gap block 설계에 따라 동일한 크기와 하중 조건에서도 다양한 변형 양상을 가질 수 있다. 이러한 특성을 활용하여, 본 연구에서는 제품 이송 과정에서 발생되는 주름과 같은 결함을 최소화하기 위한 Carbonfiber reinforced plastic (CFRP) 이중 롤러의 Gap block 설계 방법을 제안한다. 가장 먼저, Gap block에 대한 주요 설계 변수와 공정 정밀도를 고려한 분석 case들을 선정하고, 유한 요소 해석을 활용하여 CFRP 이중 롤러의 변형 양상을 추출한다. 여기서, 본 연구의 목적을 만족하는 최적의 Gap block 설계를 수행하기 위해, 제품과 롤러가 접촉하는 지점들 간의 변형 편차에 기반하여 CFRP 이중 롤러의 변형 양상들을 비교 분석한다. 그 결과, 본 연구에서 제안한 Gap block 설계 방법을 통해, 롤러의 직경 또는 길이와 같은 전체적인 크기 변화없이 제품 이송 시 결함을 크게 감소시킬 수 있는 최적화된 CFRP 이중 롤러를 구축할 수 있었다.

• 한국전산유체공학회지
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• 제16권3호
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• pp.95-103
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• 2011

In the block type VHTR core, there are inevitable gaps among core blocks for the installation and refueling of the fuel blocks. These gaps are called bypass gap and the bypass flow is defined as a coolant flows through the bypass gap. Distribution of core bypass flow varies according to the reactor operation since the graphite core blocks are deformed by the fast neutron irradiation and thermal expansion. Furthermore, the cross-flow through an interfacial gap between the stacked blocks causes flow mixing between the coolant holes and bypass gap, so that complicated flow distribution occurs in the core. Since the bypass flow affects core thermal margin and reactor efficiency, accurate prediction and evaluation of the core bypass flow are very important. In this regard, experimental and computational studies were carried out to evaluate the core bypass flow distribution. A multi-block experimental apparatus was constructed to measure flow and pressure distribution. Multi-block effect such as cross flow phenomenon was investigated in the experiment. The experimental data were used to validate a CFD model foranalysis of bypass flow characteristics in detail.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.626-630
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• 2005

This paper presents a novel Intelligent-Welding-Carriage (IWC) for automation of curved block in shipbuilding. The curved block is usually used in both front and back side of the ship. In curved block root gap is big, $1{\sim}7$ [mm] and inclination, $0{\sim}30$ [deg]. Since available conventional carriage type is limited to use below root gap of 3 [mm], only manual welding is employed in curved block. To adopt an IWC in curved block, it requires control of the welding conditions, i.e., voltage, current and travel speed, with respect to root gap and inclination to achieve good welding quality. In this paper, an IWC is developed for automization of welding operation to accommodate gap and inclination. Kinematics model and dynamics using Lagrangian formulation of the manipulator is introduced. IWC utilizes a database to perform accurate welding. The database is programmed based on numerous experimental test results with respect to gap, inclination, material, travel speed, weaving condition, voltage, and current. Finally, experimental result using PID control is addressed for verify the trajectory tracking accuracy of end-effector.

• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.171-176
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• 2005

This paper presents a novel Intelligent-Welding-Carriage (IWC) for automation of curved block in shipbuilding. The curved block is usually used in both front and back side of the ship. In curved block root gap is big, 1-7 (mm) and inclination, 0-30 (deg). Since available conventional carriage type is limited to use below root gap of 3 (mm), only manual welding is employed in curved block. To adopt an IWC in curved block, it requires control of the welding conditions, i.e., voltage. current, weaving speed, dwell time and travel speed, with respect to root gap and inclination to achieve good welding qualify. In this paper, an IWC is developed for automization of welding operation to accommodate gap and inclination. Kinematics model and dynamics using Lagrangian formulation of the manipulator is introduced. IWC utilizes a database to perform accurate welding. The database is programmed based on numerous experimental test results with respect to gap, inclination, material, travel speed, weaving condition, voltage, and current. Finally, experimental result using PID control is addressed for verifying the trajectory tracking accuracy of end-effector.

• 지질공학
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• 제32권4호
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• pp.661-670
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• 2022

기후변화로 인한 극한 강우 및 지구 온난화로 인해 도심지 홍수 및 열성현상 저감을 위한 대책이 필요한 실정이다. 이에 본 연구에서는 보강섬유(아라미드, 탄소섬유)를 이용한 친환경 투수블록을 개발하고자 하였고, 기존의 투수블록과 비교하여 환경문제 및 구조적인 안정성을 확보할 수 있도록 최적의 시멘트 사용량일 줄이고 산업부산물인 고로슬래브 미분말을 사용한 배합비를 개발하고자 하였다. 실험결과, 일축압축시험을 실시한 결과 재령 28일을 기준으로 섬유를 보강하지 않은 경우는 26.1 MPa, 탄소섬유의 경우는 29.4 MPa, 아라미드섬유의 경우는 31.82 MPa인 것을 확인할 수 있었다. 인터로킹 오차시험의 경우 각 구역에서 1.5 cm, 1.6 cm, 2 cm로 적절한 틈이 있는 모습을 확인할 수 있었다. 투수시험의 결과는 섬유가 보강되지 않은 경우 k = 1.12 × 10^-2 cm/sec, 아라미드섬유는 k = 1.13 × 10^-2 cm/sec, 탄소섬유는 k = 1.11 × 10^-2 cm/sec으로 비슷한 것을 확인할 수 있었으며 기준인, 1.0 × 10^-2 cm/sec 보다는 크게 측정된 것을 확인할 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.341-343
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• 2012

This study introduces a method for computation of process and operation gap in the specific construction operation(i.e., RC frame construction applying a block-grouping scheme) using CYCLONE-based simulation modeling and analysis technique. Since uncertainty of construction environment exists, a thoughtful production planning is required to effectively deal with a risk resulting in schedule delay in advance. This study presents the concepts of a time delay occurred in a process level and operation level in a operation model, and a method of measuring gap-times in each level while the simulation progresses. It helps a site manager to decide how many segmentation in a construction block is suitable for eliminating unproductive time-delays under the constrained resources (e.g., laborer, equipment). A case study presents a network model representing a three segmented RC frame work, and result obtained from the simulation experiment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.92-97
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• 2009

The performance of cooling fan is affected by many peripheral parts, such as radiator, condenser, engine block and etc. Higher power has been requested in more confined automobile engine room. Thus, cooling performance becomes very important to remove the heat generated from the automobile engine more efficiently. In this paper, the performance of cooling fan including effects of engine block is investigated by using a fan tester based on the ASHRAE and the AMCA standards. A flow rate - gap distance curves and a flow rate - engine block constant curves are obtained from this study.

• Macromolecular Research
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• 제15권3호
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• pp.225-233
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• 2007

To improve the poor mechanical and low-temperature properties of glycidyl azide polymer (GAP)-based propellants, the addition of binders was investigated using GAP and flexible polymer backbone-structural polycaprolactone (PCP) at various weight(wt) ratios, and varying the ratio of Desmodur N-100 pluriisocyanate (N-100) to isophorone diisocyanate (IPDI). Using Gee's theory, the solubility parameter of the PCP network was determined, in order to elucidate the physical and chemical interaction between GAP and PCP. The structure of the binder networks was characterized by measuring the cross-link densities and molecular weights between cross-links ($M_c$) obtained by a swelling experiment using Flory-Rhener theory. The thermal and mechanical properties of the segmented block copolyurethane (GAP-b-PCP) binders prepared by the incorporation of PCP into the binder recipes were investigated, along with the effect of the different curatives ratios.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.61-62
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• 2009

This paper describes the characteristics of lightning impulse current of ZnO block for transmission line arrester with external gap. The ageing parameters of lightning arresters ate impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by impulse current. Total energy applied to the ZnO arrester each time is $4/10{\mu}s$, 30kA and $2/20{\mu}s$, 10kA impulse current. Before and After the test, the residual voltage variation of varistors passed was below 5%. According to the test, it is thought that the ZnO arrester shows good stability with impulse current test.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.458-459
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• 2007

This paper describes the characteristics of lightning impulse current of ZnO block for transmission line arrester with external gap. The ageing parameters of lightning arresters are impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by impulse current. Total energy applied to the ZnO arrester each time is $4/10{\mu}s$, 30kA and $2/20{\mu}s$, 10kA impulse current. Before and After the test, the residual voltage variation of varistors passed was below 5%. According to the test, it is thought that the ZnO arrester shows good stability with impulse current test.