• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.4
• /
• pp.807-815
• /
• 2017

For liquid rocket engine(LRE)-based space launch vehicles, longitudinal instability, often referred to as the pogo phenomenon in the literature is predicted. In the building block of system-level task, accurate dynamic modeling of a fluid-filled tank is an essential. This paper attempts to apply the virtual mass method that accounts for the interaction of the vehicle structure and the enclosed liquid oxygen to LOX-filled tanks. The virtual mass method is applied in a modal analysis considering the hydroelastic effect of the launch vehicle tank. This method involves an analysis of the fluid in the tank in the form of mass matrix. To verify the accuracy of this method, the experimental modal data of a small hemispherical tank is used. Finally, the virtual mass method is applied to a 1/8-scale space shuttle external tank. In addition, the LOX tank bottom pressure in the external tank model is estimated. The LOX tank bottom pressure is the factor required for the coupling of the LOX tank with the propulsion system. The small hemispherical tank analysis provides relatively accurate results, and the 1/8-scale space shuttle external tank provides reasonable results. The LOX tank bottom pressure is also similar to that in the numerical results of a previous analysis.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.9 no.2
• /
• pp.32-39
• /
• 2005

The effectiveness of the pogo suppression device (PSD) on the response of the piping system simulating the fuel (or oxidizer) supply lines of the rocket engines was investigated. The system response defined as the ratio of the flow rate to the pressure in the main tube was obtained for various PSD gas volumes $((0\~2)\times10^{-3}m^3)$ and three different baffle hole diameters (5, 50, 115mm). Existence of a gas volume in the PSD reduced the system resonance frequency. With a larger gas volume, the resonance frequency became lower, but only slightly, while the fluctuations of the main tube pressure and the flow rate damped down considerably. The resonance frequency decreased with the increase of the PSD inlet restriction (or the decrease of the baffle hole diameter), though slightly. However, with a larger inlet restriction, the PSD pressure wave showed a delayed response with the smaller amplitude compared to the pressure variation in the main tube.

• Journal of Arbitration Studies
• /
• v.15 no.2
• /
• pp.37-59
• /
• 2005

Trade between Korea and Quingdao, Sandongseung has been developed into Private Trade from the Tributary Trade of Silla. Today there are around 6,000 Korean Enterprises in Quingdao, being $22.5\%$ of total Quingdao trades and $60\%$ in the number of investments and monetary scale. Korea is in the first rank among Quingdao's trade parteners. Trade Dispute Settlement System, however, is still in poor condition. It should be improved for the activation of trade. The big solution is the Unification of Arbitration Procedure. For it, First, The staff of The Korean Commercial Arbitration Board should be dispatched to Quingdao Arbitration Commission. Second, there should be common arbitration rules between two institutes.(The Korean Commercial Arbitration Board and Quingdao Arbitration Commission). Third, a single arbitration panel should be made. Fourth, there should be the unification of methods in choosing the place of arbitration and arbitrators. Finally, a common arbitration institute should be installed.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.7 no.4
• /
• pp.10-18
• /
• 2003

In the present study, several different types of PSD performance test systems were reviewed. Basically there are two methods to pulsate the system; whole-feeding-system pulsation and working-fluid pulsation. The latter method adopts either a piston-type pulsator or a restrict-type pulsator The working-fluid pulsation using a restrict-type pulsator was considered to be the most appropriate experimental system to study the effects of the primary parameters, and a practical design of the system was proposed.

• Journal of Technology Innovation
• /
• v.14 no.2
• /
• pp.1-27
• /
• 2006

This paper rejuvenates the existing discussion on the importance of cluster approach to industry development strategies. Current evidences suggest that the shape of economic policy and practice is changing significantly around the world. Governments continually search for new tools and policy formulas to improve economic performance and create economic prosperity for all citizens. In this context a more proactive and strategic role for government in support of the cluster-based economic development model has emerged. This paper uses Singapore's petrochemical industry as an example to study the cluster approach to industry development. In doing so, there is much optimism to the importance of state and its institutions to play a significant role on industry development. Nevertheless, the study also raises doubts on whether the cluster-based strategy is due to the concept itself or due to other important factors.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03b
• /
• pp.424-427
• /
• 2008

The longitudinal instability (POGO) of the rocket should not be occurred during the whole flight time for the large class liquid propulsion system to complete a mission successfully. The longitudinal instability is caused by the resonance between the propulsion system and rocket structure in the low frequency range below 50Hz, ordinarily. We can consider various types of propulsion system in the early stage of rocket development. So the longitudinal instability analysis tool is needed for corresponding to each propulsion system. This article deals the generalized method applied to the analysis on the low frequency dynamic characteristics of various types of liquid propulsion system.

• International Journal of Fluid Machinery and Systems
• /
• v.10 no.3
• /
• pp.307-317
• /
• 2017

In liquid-propellant rockets, POGO instability can occur, in which a fluctuation of propellant supply to the engine, a thrust fluctuation, and a structural vibration are coupled. For the prediction of this instability, it is required to provide dynamic characteristics of the pump represented as the transfer matrix correlating the upstream and downstream pressure and flow rate fluctuations. In the present study, the flow rate fluctuation is evaluated from the fluctuation of pressure difference at the different locations assuming that the fluctuation is caused by the inertia of the flow rate fluctuation. The experiments were performed in some flow conditions, and it was shown that the tendencies of dynamic characteristics are related to excitation frequencies, cavitation numbers and flow rate coefficients.

• Korean Journal of Microbiology
• /
• v.27 no.2
• /
• pp.77-84
• /
• 1989

The temperature sensitive (ts) mutation on RNA1 gene of Saccharomyces cerevisiae prevents growth at restrictive temperature ($36^{\circ}C$) by accumulation of precursor tRNA, rRNA and mRNA (Hutchison et al., 1969; Shiokawa and Pogo, 1974; Hopper et al., 1978). RNA1 gene was cloned by complementation of the temperature sensitive growth defect of an rna1-1 mutant strain and identified by retransformation and concomitant loss of recombinant plasmid on non-selective condition. By deletion mapping, it was found that RNA1 gene resides within 3.5kb of BgII fragment.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.19 no.2
• /
• pp.73-80
• /
• 2015

It had been almost a half century since Apollo Mission was ended. However, in these days, a lot of researches are being conducted for restoration and making improvements in technologies used in Saturn V rocket's development. This study reviews the first stage of Saturn V rocket(S-IC), from development history to technologies in various subsystems such as engine purge system, POGO suppression system, hydraulic and pneumatic control system, propellant dispersion system, telemetry system and retrorocket system. Understandings of S-IC stage's operation systems would be helpful in understanding of launch vehicle system and reduction of time and cost in future development process.

• Acta Via Serica
• /
• v.8 no.2
• /
• pp.125-154
• /
• 2023

Historically, commerce was a significant factor in the proliferation and development of Buddhism, which is especially manifest in the cult of the bodhisattva Avalokiteśvara. Iconographic and textual evidence testifies that maritime trade on the Indian Ocean played a fundamental role in the formation of Avalokiteśvara worship. The sea was also a major conduit through which elements of the Avalokiteśvara faith were transmitted from India through China to Korea and Japan, the easternmost ends of the Silk Road. These elements include Avalokiteśvara's role as a maritime savior, oceanic symbolism, and the concept of the bodhisattva's worldly abode, Potalaka. Cultic sites dedicated to maritime safety were established at important transport hubs in East Asia. Due to China's strategic location on the Silk Road, as well as its cultural influence, the most important cultic sites were founded in China, first on the Shandong Peninsula, then in the southern Jiangnan region, in present-day Zhejiang Province. Especially notable is the role that Korean seafarers played in this process by assisting monks in search of the Dharma, establishing temples, and transmitting religious beliefs across the ocean. The present study focuses on the role that maritime figures played in the cultural exchanges between Korea, China, and Japan examined through Avalokiteśvara faith. By this, it aims to demonstrate how Korean seafarers inherited and continued the traditional relationship between commerce and Buddhism, while extending the Maritime Silk Road to the "East Asian Mediterranean."