• 한국연소학회지
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• 제21권4호
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• pp.16-22
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• 2016

Pressure and temperature variations in a shock tube have been studied numerically by changing the diameter ratio of a driven part to a driver part. There are five cases where the adopted diameter ratios are 40%, 50%, 60%, 80%, and 100% respectively. The diameter of the driver part remains unchanged meanwhile the shock tube driven part diameter increases from 40% to 100% of the driver part. In the 100% ratio case, the driver part and driven parts have the same diameter of 66.9 mm. As the diameter ratio decreases, the pressure in the shock tube and available test time are increased.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.68-71
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• 2004

The experiments for NACA airfoils are conducted as the preliminary study for the aerodynamic characteristics of the transonic airfoil flow in the shock tube. The test section configurations were designed to use shock tube as simple and less costly experimental facility generating transonic flow at relatively high Reynolds numbers. Experiments at hot gas Mach numbers of 0.80, 0.82 and 0.84, Reynolds numbers of about $1.2\times10^6$ on airfoil chord length and angle of attack of $0^{\circ}\;and\;2^{\circ}$ were carried out by means of shadowgraph visualization method and static pressure measurements. Visualization results were compared with the corresponding results from the conventional transonic wind tunnel tests. The results of study showed that present shock tube facility is useful to study the proper performance characteristics in transonic Mach number range.

• 한국염색가공학회지
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• 제26권2호
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• pp.106-113
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• 2014

Work-related falls are a major problem in the construction and roofing industries. To avoid serious injury to the worker caused by high decelerations or forces, different systems to absorb the energy of a fall are implemented in personal protective equipment. In this study, shock energy absorber lanyard protection tube was prepared using high tenacity PET fiber, P-aramid fiber, and UHMWPE fiber, respectively. Dynamic load test and static load test, bursting strength test based on the Korea fall protection equipment standard(Korea Occupational Safety & Health Agency standard 2013-13) or conformity European safety test(CE : EN355) were conducted. Especially maximum arrest force by dynamic load test of energy absorber showed below 6,000N.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.202-204
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• 2002

The supurfluid shock tube facility has been developed as a versatile tool for experimental research of low-temperature thermo-fluid dynamic phenomena The shock tube is designed to operate with the He II filled test section which is immersed in superfluid helium. The thermo-dynamic phenomena occurred in this facility are measured using pressure transducers, superconductive temperature sensor and visualization method. In this paper, the design and performance of the superfluid shock tube facility and the superconductive temperature sensor is presented.

• 한국항공우주학회지
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• 제34권2호
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• pp.11-16
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• 2006

충격파관을 이용하여 NACA와 이중쐐기 날개 주변의 천음속 유동에 대한 실험적 연구가 수행되었다. 벽면효과와 반사충격파의 영향을 최소화하기 위해 슬랏벽과 챔버를 가지는 실험부가 설계되었으며 이를 통해 충격과관을 비교적 높은 레이놀즈수의 천음속 유동을 발생시키는 간단하고 경제적인 풍동장치로 이용하고자 하였다. 열기류 마하수 0.80~0.84, 레이놀즈수 약 $1.2{\times}10^6$ 받음각 $0^{\circ}$ 와 $2^{\circ}$의 유동 조건에서의 천음속 날개 유동은 섀도우그래프법에 의해 가시화되었다. 날개 주변의 충격파 분포는 기존의 일반 천음속 풍동 실험의 결과와 비교되었다. 실험결과는 본 실험에 사용된 충격파관은 실험 마하수 범위와 날개에 대해 천음속 풍동으로서의 유효한 성능 특성을 나타내었다.

• 국제강구조저널
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• 제18권5호
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• pp.1541-1559
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• 2018

This paper addresses the dynamic loading characteristics of the shock tube onto sandwich steel beams as an efficient and accurate alternative to time consuming and complicated fluid structure interaction using finite element modeling. The corrugated sandwich steel beam consists of top and bottom flat substrates of steel 1018 and corrugated cores of steel 1008. The corrugated core layers are arranged with non-uniform thicknesses thus making sandwich beam graded. This sandwich beam is analogous to a steel beam with web and flanges. Substrates correspond to flanges and cores to web. The stress-strain relations of steel 1018 at high strain rates are measured using the split-Hopkinson pressure. Both carbon steels are assumed to follow bilinear strain hardening and strain rate-dependence. The present finite element modeling procedure with an improved dynamic impulse loading assumption is validated with a set of shock tube experiments, and it provides excellent correlation based on Russell error estimation with the test results. Four corrugated graded steel core arrangements are taken into account for core design parameters in order to maximize mitigation of blast load effects onto the structure. In addition, numerical study of four corrugated steel core placed in a reverse order is done using the validated finite element model. The dynamic behavior of the reversed steel core arrangement is compared with the normal core arrangement for deflections, contact force between support and specimen and plastic energy absorption.

• 한국추진공학회지
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• 제25권6호
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• pp.20-28
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• 2021

극초음속 유동 시험에 활용되고 있는 충격파 터널 등은 원하는 시험 조건을 얻기 위해 격막의 파열 압력비를 맞추어 운용한다. 주로 금속 재질로 이루어진 격막은 정확한 압력비를 맞추기 위해 특정 형태로 가공하거나 강제 파열 장치를 사용하여 개방한다. 격막의 개방 과정은 수백 microsecond 동안 파열과 변형을 통해 이루어지는데, 동일한 압력비에서도 개방 정도와 개방 소요 시간에 따라 시험 조건이 달라질 수 있을 것으로 예상된다. 본 연구에서는 격막의 두께 및 재질 차이를 반영할 수 있는 파열모델을 적용하여 수치 해석을 수행하고 충격파의 형성과 정체 조건의 특성에 대해 살펴보았다. 격막 파열로 인해 생성된 충격파의 속도는 격막 개방 속도에 비례하였으며, 격막의 최종 개폐율 및 소요 시간에 따라 저압관 끝단에 형성되는 정체 압력과 시험 시간에 차이가 나타나는 것을 확인할 수 있었다.

• 한국산학기술학회논문지
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• 제12권7호
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• pp.2919-2924
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• 2011

자동서랍함용 완충기는 서랍을 여닫을 때 충격을 흡수하고 속도를 조절하는 역할을 해 준다. 완충기 튜브는 완충기의 구성품을 에워 쌓고 있는 원통 모양의 케이스이며 아세탈 재질로 되어있다. 본 연구는 사출 성형 공정에서 제작된 완충기 튜브의 품질 안정성을 평가하는 데 목적이 있다. 완충기 튜브는 4 캐비티 냉각장치를 갖춘 사출 성형공정에서 제작된다. 본 연구에서는 완충기 튜브의 품질 안정을 판단하기 위해 분석과 시험이 수행되었다. 분석과 시험은 컴퓨터 시뮬레이션을 통한 품질 분석과 연구된 튜브에 대한 외산품과의 성능 비교 시험이다. 사출 압력은 87.6 MPa로, 전체 휨량은 0.07~1.0 mm로 계산하였다. 연구된 튜브와 외산품을 비교해 볼 때 튜브의 최대 압축-하중은 231 kgf, 구간별 변위-하중은 0.05 kgf, 그리고 또 튜브 내경의 표면거칠기(Ra)는 $0.02\;{\mu}m$ 향상되었다. 결과적으로 사출 성형 공정에서 제작되어지는 연구된 튜브의 품질은 안정되었고 성능이 우수함을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.293-297
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• 2004

The ignition of monomethylamine was studied in reflected shock waves over the temperature range of 1255- 1579 K and the pressure range of 1.04-1.51 bar. The ignition delay time was measured by the sudden increase of pressure profile and the radiation emitted by OH radicals. The relationship between the ignition delay time and the concentrations of monomethylamine and oxygen was determined in the form of mass-action expressions with an Arrhenius temperature dependence. In contrast to the behavior observed in hydrocarbons, monomethylamine acts to accelerate rather than inhibit its own ignition. And numerical modeling of the ignition of $CH_3NH_2$ has also been carried out to test the several kinetic mechanisms.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1997년도 제8회 학술강연회논문집
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• pp.43-51
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• 1997

Steady and unsteady numerical simulations are conducted for the experiments performed to investigate the ram accelerator flow field by using the expansion tube facility in Stanford University. Navier-Stokes equations for chemically reacting flows are analyzed by fully implicit and time accurate numerical methods with Jachimowski's detailed chemistry model for hydrogen-air combustion involving 9 species and 19 reaction steps. Although the steady state assumption shows a good agreement with the experimental schlieren and OH PLIF images for the case of $2H_2$+$O_2$+$17N_2$, it fails in reproducing the combustion region behind the shock intersection point shown in the case of $2H_2$+$O_2$+$12N_2$, mixture. Therefore, an unsteady numerical simulation is conducted for this case and the result shows all the detailed flow stabilization process. The experimental result is revealed to be an instantaneous result during the flow stabilization process. The combustion behind the shock intersection point is the result of a normal detonation formed by the intersection of strong oblique shocks that exist at early stage of the stabilization process. At final stage, the combustion region behind the shock intersection point disappears and the steady state result is retained. The time required for stabilization of the reacting flow in the model ram accelerator is found to be very long in comparison with the experimental test time.