• Solar Energy
• /
• v.9 no.3
• /
• pp.44-54
• /
• 1989

Heat transfer phenomena during inward melting process of the phase change material were studied experimentally. N-docosane paraffin [$C_{22}H_{46}$] is used for phase change material and its melting temperature is $42.5^{\circ}C$. Experiments were performed for melting of an initially no-sub cooled or subcooled solid in a horizontal cylinder, in order to compare and investigate the radial temperature distribution, ratio of melting and melted mass, various energy components stored from the cylinder wall, figure of the melting front in the horizontal cylinder. The solid-liquid interface motion during phase change was recorded photographically. The experimental results reaffirmed the dominant role played by the conduction at early stage, by the natural convection at longer time during inward melting in the horizontal cylinder. Ratio of melting and melted mass are more influenced by wall temperature, rather than by the initial temperature of solid. The latent energy is the largest contributor to the total stored energy.

• Journal of the Korean Society of Visualization
• /
• v.1 no.2
• /
• pp.52-57
• /
• 2003

The present paper investigated the effect of ultrasonic vibrations on the melting process of a phase-change material (PCM). The melting process in the square cavity with a heated vertical wall has been studied in terms of acoustic streaming. In the present study, applying with ultrasonic vibrations to the liquid were found to induce acoustic streaming which was clearly observed using by a particle image velocimetry (PIV) and a thermal infrared camera. The experimental results revealed that acoustic streaming could accelerate the melting process as much as 2.5 times, compared to the rate of natural melting (i. e., the melting without acoustic streaming). In addition, temperature and Nusselt numbers over time provided conclusive evidence of the important role of the acoustic streaming on the melting phenomena of the PCM.

• Journal of Ocean Engineering and Technology
• /
• v.1 no.1
• /
• pp.49-56
• /
• 1987

The dynamic behaviour of a marine riser was studied theoretically and experimentally. In linear analysis, the natural frequencies and mode shapes of the riser were obtained from the experiment and they were found to be in good agreement with theoretical results by using a simple asymptotic formula. In nonlinear ananlysis including viscous drag and large displacement, a numerical-perturbation technique based on the derived linear asymptotic solutions is used to predict the displacements and stresses of the riser in harmonic motion. These results were also compared with experimental data and found to be in general in good agreement.

• Journal of Ocean Engineering and Technology
• /
• v.17 no.4
• /
• pp.8-15
• /
• 2003

When a typoon sets into harbour, a moored ship shows erratic motions and even mooring line failure may occur. such troubles may be caused by harbour resonance phenomena, resulting in large motion amplitudes at low frequency, which is close ti the natural frequency of th moored ship. The nonlinear motions of a ship moored to quay are simulated under external forces due to wave, current including mooring forces in time domain. The forces due to waves are obtained from source and dipole distribution method in the frequency domain. The current forces are calculated by using slow motion maneuvering equation in the horizontal plane. The wind forces are calculated from the empirical formula of ABS and the mooring forces of ropes and fenders are modeled as linear spring.

• Korean Institute of Interior Design Journal
• /
• no.34
• /
• pp.45-52
• /
• 2002

It is noted that the expressionistic feature appears as one of characteristic phenomena for representing the regional culture and economic level. In architecture, it seems to be difficult to define the expressionism in a concrete way because of lots of meanings the word originally has. In this study, the expressionistic feature is defined as a mode which impresses the users emotionally with strength or as a touching and stimulating one, contrary to the designing conception which pursues only the rationality and the functionality. These features can be expressed as designing methods such as organic form, adoption of natural design factor, decisive opening of space or its extreme closing, contrast of mutually opposite components, or application of basic design components.These methods described above are largely categorized into spatial form, openness, scale and design component and also are studied for each example within the scope of these categories. This study has significance in conceptualizing this expressionistic tendency and in analyzing some detailed aspects for expression.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.05a
• /
• pp.737-739
• /
• 2003

Today, satellite remote sensing and geographic information systems plays an important role as a advanced science and technology, and becomes a superpower tool of the study and research in various fields of Earth Science. This study reviews the application of satellite remote sensing and geographic information systems for many specialists in the fields of the fishery and ocean science. In future, satellite remote sensing and geographic information systems will be greatly used to observed, monitor and predict various phenomena associated with the fisheries and oceans, in order to seek safety in a natural disaster, and menage and conserve the fisheries and resources and the oceanic environments.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.11
• /
• pp.2922-2931
• /
• 1994

We propose a modified 6-node element, where the sampling point of Gauss quadrature moved in the thickness direction. The modified 6-node element has been applied to static problems and forced motion analyses. In this study, this method is extended to the finite element analysis of the natural frequencies of two dimensional problems. We also propose a modified 16-node element for three dimensional problems, which behaves much like a 20-node element with smaller degree of freedom. The modified 6-node and 16-node elements have been applied to the modal analyses of beams and plates, respectively. The results agree well with the results of the 8-node or 20-node element models.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.41-44
• /
• 2007

Steam reforming reaction of natural gas is an important process for fuelcell commercialization. In this paper, steam reforming reaction is studied by numerical method. Pseudo-homogeneous model is incorporated for chemical reactions and one medium approach is used to take into account thermally equilibrium phenomena between catalyst and bulk gas. The model is validated with our experimental results under the same operating conditions. Because performance of reformer has relation to heat flux from wall, heat flux profiles was investigated by using Nusselt number. Value of Nusselt number in steam reformer is larger than one in channel, which does not have chemical reaction because steam reforming reaction is an endothermic reaction. When the difference of Nusselt number at the front and the rear is larger, performance is improved.

• Proceedings of KOSOMES biannual meeting
• /
• 2003.05a
• /
• pp.141-151
• /
• 2003

In this study the writer would like to study the art of navigation in the Era of Silla. For the purpose of this study, the writer studied ship's log book of Ennin's Diary, the ancient ship's structures of Korean, Chinese, Japanese, winds and ocean currents around Korean Peninsular which effect the navigation of sailing ship, and ancient reference books and materials. The result of this study. in the ship's structure in the Era of Silla. bottom structure is considered flat and V-Shaped type, and sailing ship had anchor, sail, considerable deckhouse, transverse bulkhead. And the ship's main materials of sailing ship was wood. partially used irons in the panting structures. In the art of navigation, navigators used winds, ocean current, anchor, sail, depth and color of sea water, lights, ballast. Especially navigators used astrologers and geomancers for astronomical observation, weather forecast, natural phenomena.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1995.04a
• /
• pp.221-231
• /
• 1995

This paper proposes that a GDSS research boundary needs to be further expanded to include more human-nature variables arising in natural group interaction processes. By doing so, we can better understand the GDSS phenomena and have a better picture for designing effective GDSS for group decisions. Specifically, this paper reviewed literature and explored variables to be further included in GDSS research arena. As results, this paper proposed an extended framework for GDSS research that includes variables that have been little considered in most empirical studies to date. Then, the variables and their relationships are used to explain the handicaps of current GDSS uses and to redirect the ways of utilizing GDSS technologies for group decision-making. Based on the framework, we suggested proposititions for the future research.