• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.6
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• pp.93-99
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• 2003

In this study, new shock absorbing system is proposed by using nano-technology based on the theoretical analysis. The new shock absorbing system is complementary to the hydraulic damper, having a cylinder-piston-orifice construction. Particularly for new shock absorbing system, the hydraulic oil is replaced by a colloidal suspension, which is composed of a porous matrix and a lyophobic fluid. The matrix of the suspension is consisted of porous micro-grains with a special architecture: they present nano-pores serially connected to micro-cavities. Until now, only experimentally qualitative studies of new shock absorbing system have been performed, but the mechanism of energy dissipation has not been clarified. This paper presents a modeling and theoretical analysis of the new shock absorbing system thermodynamics, nono-flows and energy dissipation. Compared with hydraulic system, the new shock absorbing system behaves more efficiently, which absorb a large amount of mechanical energy, without heating. The theoretical computations agree reasonably well with the experimental results. As a result. the proposed new shock absorbing system was proved to be an effective one, which can replace with the conventional one.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.832-838
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• 2011

The shock absorber with magnetic effect is suggested for a lunar lander. The shock absorber consists of a metal tube, a piston rod, and several permanent magnets moved by a piston rod in the tube, and the shock energy can be dispersed and dissipated by magnetic effects such as the magnetic force existed between a metal and magnets and the eddy current effect generated by a relative motion with a conductor and magnets. Besides, the shock-absorbing effect similar to that of a coil spring can be obtained by arranging the magnets in line, which are facing the same polar each other. The device has a very simple structure and is usable in space due to the unnecessariness of any oil or gas. The shock absorber was designed and manufactured for experiments and its spring and damping characteristics were studied by the theoretical, analytical and experimental methods.

• The tire
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• s.83
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• pp.2-9
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• 1979

OPEC의 원유가인상과 이란 정책으로써 원유가격이 대폭적으로 오르게 되었다. 제2차 oil shock의 양상이 나타나기 시작하고 있다. 원재료의 70%를 석유제품에 의존하고 있는 자동차타이어도 앞으로 이 영향을 필연적으로 받게 될 것이다. 그러므로 타이어가 석유제품과 어떠한 관계에 있는가 또 "석유고가시대"에 일본의 타이어 메이커들은 어떻게 성에너지 대책을 세우고 있는가 등을 참고적으로 이 기회에 검토해 보고자 한다. <편집자주>

• The tire
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• s.84
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• pp.35-37
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• 1979

원재료의 70%를 석유제품에 의존하고 있는 타이어산업에 있어서는 앞으로 필연적으로 받게 될 Oil Shock의 영향을 고려할 때, 원재료의 대체개발에 주목하지 않을 수 없다. 특히 최근 당면하고 있는 석유위기의 타개책과 성에너지 정책에 즈음하여, 본고는 일본 동경공대 신원 주 교수의 「80년대의 고무 원료」에 대한 해설 중에서 몇 가지 내용을 간추려 본 것이다.<편집자 주>

• Journal of Energy Engineering
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• v.1 no.1
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• pp.6-18
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• 1992

산업혁명 이래 전 세계의 에너지의 공급은 석탄에 의존하여 왔으나, 1950년대 중동의 석유개발 이후 석유자원의 편의성으로 말미암아 석탄 활용기술에 대한 연구는 미진하였다. 그후 1970년대의 oil shock이후 미국을 위시한 선진국에서 대체에너지원으로서 석탄에너지의 활용기술에 대한 연구가 활발히 진행되어져 오다가 석유 가격의 안정화에 따라 이에 대한 연구의 열기가 감소하게 되었다. (중략)

• 전기의세계
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• v.23 no.6
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• pp.27-32
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• 1974

오늘날 에너지의 수요가 날로 증대하게 되면서 그 공급보장에 대한 우려가 항상 논의의 대상이 되어오더니 지난해 갑자기 불어닥친 Oil Shock와 함께 세계각국이 한결같이 새로운 대체에너지원의 하나로서 원자력발전에 박차를 가하고 있는바 본고에서는 세계적인 원자력발전동향을 검토하고 우리나라의 에너지사정 원자력발전개발현황과 전망 및 타개되어야할 주요 문제점등을 살펴보고자 한다.

• International Journal of Fluid Machinery and Systems
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• v.8 no.1
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• pp.23-35
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• 2015

This paper presents the rotordynamic performance measurement of oil-free turbocharger (TC) supported on gas foil bearings (GFBs) for 2 liter class diesel vehicles and comparison to floating ring bearings (FRBs). Oil-free TC was designed and developed via the rotordynamic analyses using dynamic force coefficients from GFB analyses. The rotordynamics and performance of the oil-free TC was measured up to 85 krpm while being driven by a diesel vehicle engine, and compared to a commercial oil-lubricated TC supported on FRBs. The test results showed that the GFBs increased the rotor speed by ~ 20% at engine speeds of 1,500 rpm and 1,750 rpm, yielding the reduction of turbine input energy by more than 400 W. Incidentally, an external shock test on the oil-free TC casing was conducted at the rotor speed of 60 krpm, and showed a good capability of vibration damping due to the well-known dry friction mechanism of the GFBs.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.124-131
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• 2003

When a secondary gaseous flow is injected vertically into a supersonic flow through circular nozzle, a complicated structure of flow field is produced around the injection area. The interaction between the two streams produces a strong bow shock wane on the upstream side of the side-jet. The results show that bow shock wave and turbulent boundary layer interaction induces the boundary layer separation in front of the side-jet. This study is to analyze the structure of flow fields and distribution of surface pressure on the flat plate according to total pressure ratio using a supersonic cold-flow system and also to study the control force of affected side-jet. The nozzle of main flow was designed to have Mach 2.88 at the exit. The injector has a sonic nozzle with 4mm diameter at the exit of the side-jet. In experiments, The oil flow visualization using a silicone oil and ink was conducted in order to analyze the structure of flow fields around the side-jet. The flow fields are visualized using the schlieren method. In this study, a computational fluid dynamic solution is also compared with experimental results.

• Journal of the Korean Operations Research and Management Science Society
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• v.7 no.1
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• pp.31-43
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• 1982

A general equilibrium growth model is constructed to analyse the income distributional impacts of the 1973 world oil crisis upon the Korean economy. Our results show that all consumer groups experienced a virtually uniform percentage reduction in their income levels. This implies that a lower income groups may be more damaged in a relative sense. In any rate, there were no domestic groups who benefit from the international oil crisis. This model could be used to figure out which social group will be most vulnerable against the next possible oil crisis we may expect in the future. Our result nay provide us a guideline for a compensating program to protect such groups against an external shock.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.3
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• pp.94-106
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• 1986

Since the oil shock of '70s the engine makers have developed new types of diesel engine with low fuel consumption. There is an obvious tendency towards the use of poorer quality fuels, such as the residual oil from chemical processes of refinery. The shaft driving generators is also widely adopted on behalf of the auxiliary diesel engines, which are driving on the expensive diesel oil and have high fuel oil consumption rates, and some mania propulsion diesel engines are equipped with reduction gear systems to get better propulsive efficiency by slower propeller revolutions. The propulsion shafting system equipped with the shaft driving generator or the geared diesel engine shafting system has flexible couplings, and it requires extensive investigations of the torsional vibration and torque fluctuation in order to ensure the acceptable operation range in service. The characteristics of misfiring must be especially examined for the high viscosity fuels to be used. Both torsional vibration and fluctuating torque resulted from misfiring, should be examined for thier effects on the flexible coupling and propulsion shafting system. This paper is to investigate and solve the above mentioned problems which must be predicted on the design-stage of marine propulsion shafting system. A computer program is developed to calculate the indicated diagram, fluctating torque and torsional vibration for both normal and misfiring conditions.