• Magazine of the Korean Society of Agricultural Engineers
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• v.6 no.1
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• pp.737-749
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• 1964

This is an attempt to find out the periodicity of the natural hydrological phenomena by the function of vibration periodicity, under the assumption that the phenomena are periodic. The result of this study at Suwon is as foIlows: 1. Annual precipitation and tota1 precipitation during summer season have the periodicity of five years. 2. Annual temperature and tota1 temperature during winter season have the periodicity of seven years. 3. The regulation curve equations of the above vibration phenomena are as foIlows: a Annual precipitation. Y = 1149-250cos2/5${\PI}$t-33 sin 2/5 t b. Total precipitation during summer season. Y=212'.9+33.06sin (2/5${\PI}$t+$88^{\circ}$13') c. Annual temperature. Y= 140.3+3.3 sin (2/7${\PI}$t+ $154^{\circ}C$55')

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.393-398
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• 2001

Pulsations, vibration and stress are the basic dynamic phenomena in power plant piping systems which directly affect system reliability. These phenomena are both acoustical and mechanical in nature and are closely interrelated. It was noticed that thermodynamic parameters were changed after replacing with new type tube bundles of reheat exchanger. It was reported later that the drain piping connecting the new bundle header with the associated drain tank is regularly pulsating at about every 3 second with 13.4㎐ and 7.5mm, p-p in amplitude. This amplitude is about 6 times higher than reference level of sound piping. The results of finite element analysis of the pipeline showed that its dominant natural frequency is 13.4㎐. The soundness is predicted whether the bending dynamic stress evaluated excesses the maximum allowable high cycle fatigue stress or not by the measured amplitude of vibration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.332-336
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• 2004

To position precision machines accurately, linear motion (LM) guides having rolling elements can be used. For ultra-accurate positioning control of the precision machines, the understanding of the dynamic behavior of the LM guide at the macro and/or micro scales is most critical, but the research on this subject is rare. The objective of the present research is to observe the vibration phenomena of the LM guide. Bails are used as the rolling elements in this work. Several experiments show the nonlinear characteristics of the LM guide such as hysteresis behavior and force-dependent natural frequencies phenomena.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.161-165
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• 2013

In this paper, possibility of controlling motion of a floating structure using a tuned liquid damper (TLD) is numerically investigated. A TLD is a tank partially filled with liquid. Sloshing phenomena of liquid inside a tank can suppress movement of the tank subject to external excitations at specific frequency. The effects of sloshing phenomena inside a rectangular floating body on its sway motion are investigated by varying excitation frequency. First, a grid-refinement study is carried out to ensure validity of grid independent numerical solutions using present numerical techniques. Then, sway motion of the floating body subjected to wave with five different frequencies are simulated. The normalized amplitudes of sway motion of the target floating body are compared over the frequency, for cases with and without water inside the floating body. It is shown that the motion of the floating body can be minimized by matching the sloshing natural frequency to excitation frequency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.10
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• pp.1029-1034
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• 2004

Linear motion ( LM) guides having rolling elements have been used to position precision machines accurately. For ultra-accurate Positioning control of Precision machines, the understanding of the dynamic behavior of the LM guide at the macro and/or micro scales is most critical, but the research on this subject is rare. The objective of the present research is to investigate the vibration phenomena of the LM guide where balls are used as the rolling elements. Several experiments show the nonlinear characteristics of the LM guide such as hysteresis behavior and force-dependent natural frequencies phenomena.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.534-537
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• 2012

Hydroelastic effects on sloshing phenomena in a rectangular tank are numerically investigated. The dimension of the tank is $1000mm{\times}600mm$, and the filling ratio of water is 20% of tank height. One of the side walls of tank is assumed to be flexible. The tank is excited into sway motion with amplitude of 100mm and frequency of 0.53Hz that is first natural frequency of water inside the tank. Prediction results for time histories of pressure and displacement of flexible and rigid walls are compared to quantitatively assess hydroelastic effects on sloshing phenomena.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1059-1064
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• 2008

The present study is to reduce the thermal phenomena and stack effect of nude elevator of the high-rise building used CFD simulation. Since many High-rise buildings used the curtain-wall glass, thermal phenomena and stack effect can easily occur at hot and cold season, respectively. The simulation has been conducted and verified for the effects of the amount of suppling air to the environment of the inside nude elevator shaft. The results of simulations show that the problems due to the thermal and stack effect will be reduced by enforced ventilation or natural ventilation and those will be presented by temperature and velocity profiles and pressure differences.

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.937-942
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• 2003

The relaxation phenomena of ionic currents through the charged membrane under the constant applied potentials has been studied. The formulation was obtained for the non stationary current by assuming that the ion mobility is independent of concentration and the potential gradient is a constant within membrane, and it was applied to the experimental results with the sulfonated polystyrene collodion base membrane. It has been shown that the initial ion distributions in the membrane play a predominant role in the relaxation phenomena.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.155-164
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• 1996

Dual-fuel engines are being researched with emphasis on the possible types of natural gas supply systems. Hence, a three-dimensional combustion model by using finite volume method was developed to provide a fundamental understanding of the auto-ignition of pilot distillate and subsequent burning of natural gas, when the natural gas as well as the distillate was directly injected into a quiescent diesel engine like combustion bomb tests and the numerical results were investigated for the mixed combustion phenomena. With high-pressure natural gas injection, it was found that the gaseous fuel injection characteristics had to be well harmonised with that of the pilot distillate. For better combustion efficiency, however, further researches are required for the optimisation of injection system in the existence of air motion.

• The Southeast Asian review
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• v.21 no.2
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• pp.77-123
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• 2011

Recently, Southeast Asian people, its food, natural sceneries and so on have been increasingly exposed to Korean people through mass media and multi-cultural events. At the same time, Koreans can frequently encounter Southeast Asians in their everyday lives. Thus, specific images and discourses of Southeast Asia has been established in our society, which creates a new social trend called 'Southeast Asia phenomena'. In short, 'Southeast Asia phenomena' means a totality of Korean people's experience of Southeast Asian and their perception on the region. On the one hand, 'Southeast Asia phenomena' is a result of inflow of Southeast Asians and their culture into Korea. On the other hand, it is also a consequence of Korean people's understanding of Southeast Asia from their trip to Southeast Asia or from their interactions with Southeast Asian people. This article aims to analyze the origin and diffusion of 'Southeast Asian Phenomena' in Korea in the context of Southeast Asia focusing on 4 topics, that is, migrant workers, overseas investments, retirement migration, study-abroad categorized as human movement. This article is also about a country-by-country comparative analysis both at the macro level and the micro level. At the macro level, overseas investments and trade, human exchanges, positive perception to Koreans which considered to be the structural causes become a strong mechanism playing a important bridge role between Korea and Southeast Asia. So these create the high probability of the emergence of 'Southeast Asian Phenomena' At the micro level which is more direct causes of 'Southeast Asian Phenomena', the economic cause is the most important common cause for 4 Southeast Asian Phenomena. Additionally, Korean wave is also remarkable common cause creating 'Southeast Asian Phenomena' even it is not the origin in the context of Southeast Asia. The diffusion of 'Southeast Asian Phenomena' is different by the topics and the elements contributing to create the favorable situation for the diffusion are not only overseas investments and trade, human exchanges at the macro level but also policy elements at the micro level. The relative differences of the causes of 'Southeast Asian Phenomena' in the country-by-country analysis are found. Regarding overseas investments in Vietnam and Cambodia, the economic degree of freedom in Cambodia is higher than in Vietnam. Even Korean Wave has had the longer history in Vietnam, but the favorable perspectives on Korean Wave are stronger in Cambodia. For migrant workers from Vietnam and Indonesia, the economic causes in Vietnam are more significant than in Indonesia. The impact of Korean Wave is stronger in Vietnam than in Indonesia. In case of study-abroad, the social-cultural elements and policy elements are more diverse in Malaysia than in Korea. For the Korean retirees who immigrate to the Philippines and Malaysia, the economic causes in the Philippines is more significant in Malaysia.