• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.7
• /
• pp.525-534
• /
• 2019

Water rocket is a pressurized liquid propellant rocket that shares the same basic principles of space launch vehicles. Water rockets can be used as an engineering educational material for the liquid rocket principles and the launch vehicle systems, far beyond the scope of K-12 level science education. In this paper, the principles and theories of water rocket propulsion and flight dynamics was investigated at the level of undergraduate rocket engineering classes. Also, the system level design and operation of water rocket is summarized by including the components of launch vehicle, launch pad, payload and recovery as well as altitude measurement methods.

• Korean Institute of Interior Design Journal
• /
• v.15 no.6 s.59
• /
• pp.205-212
• /
• 2006

The premise of this study is that an ultimate objective in planning an exhibition space is spectators' experiences shaped by a result of their first-hand experiences and responses within an exhibition space, and this result can be recognized in the spectators' movement. Thus, the sign system that can directly affects viewers' main line of flow and movement patterns was examined vis--vis a mutually complementary relation in a triangular composition with the structure of exhibition space and the exhibition contents. Based on the findings, predictive values before and after a complementary application of the sign system to the structure of exhibition space was analyzed and its validity was assessed. The results of this research analysis were drawn as follows. It was shown that an understanding of the locations of direction signs and the degree of recognition can function as an important factor to predict viewers' movement, along with an understanding of topological characteristics of an exhibition space. In terms of the connection and disconnection of space units that form the space structure, it suggests that the distribution of signs and the degree of recognition can adjust the degree of connection and disconnection. Even though exhibition spaces for research subjects were selected from a relatively large number of museums, but the research was limited with a focus on the structure of exhibition space and sign systems. Thus, it is proposed that future studies should be conducted by including varieties of exhibition and environmental factors.

• Korean Institute of Interior Design Journal
• /
• v.19 no.6
• /
• pp.47-58
• /
• 2010

Frank Lloyd Wright(1867-1959) was regarded as the pioneer of the modern architecture in the beginning and transition period of 20th century. His works have the pure shape form which have the deep relationship with the organic architecture. Wright told himself that the Froebel System had an influence on his works a lot. This study have researched about the three dimensional application of the Froebel System in his works with assembling and disassembling. Also the two dimensional application in the diagonal and circular plans are the one of the subjects here. The following conclusions are reached. First, The similar of the Wright's works and the Froebel System was the application of the similar principles rather than the copy of the method, which are the accent of the center, the composition of the part and whole, the understanding of the composition principle through the unit system and the unfolding of the crystal by rotation. Even thought the Wright's works have the triangle, square, hexagonal shape, the way of the expansion from the centered space was same. Also the space formed by the division of the center space, unfolds making the part and whole by overlap and continuation. The 2nd Froebel make space decided by the Net and Crystal Lattices which have the crystal characteristics by the rotation. The new geometric architecture, pinwheel, was created by this method. The application of the Froebel in the Wright's works have the several sets which are the 3th, 4th, 5th, 6th Froebels, 2nd, 7th Froebels and the 3th, 5th, 9th Froebels. The geometrical analysis of the square shape and the diagonal shape of the Wright's works was possible. The unfolding of the centered space can be found in the Guggenheim Museum using the analysis of the circular geometric of the 9th Froebel. The above study proves that the Froebel was not a mere tool for the basic shape training but also the main body of Wright's works which consists of the organic idea and philosophy of the space.

• Publications of The Korean Astronomical Society
• /
• v.32 no.1
• /
• pp.55-57
• /
• 2017

Presently, the number of known asteroids is more than 710,000. Knowledge of size and albedo is essential in many aspects of asteroid research, such as the chemical composition and mineralogy, the size-frequency distribution of dynamical families, and the relationship between small bodies in the outer solar system or comets. Recently, based on the infrared all-sky survey data obtained by IRAS, AKARI, and WISE, the large asteroid catalogs containing size and albedo data have been constructed. In this paper, we discuss the compositional distribution in the main belt regions based on the compiled data on size, albedo, and separately obtained taxonomic type information.

• Journal of The Korean Digital Architecture Interior Association
• /
• v.7 no.2
• /
• pp.33-41
• /
• 2007

This thesis aims at understanding Le Corbusier's architecture through study of proportion. Based on the analysis of these texts, four elements - geometry in the outline, diagonal regulation lines in the facade, arithmetic rhythm in the structure, composition in the inner space - were listed. Through these four proportional systems. ten houses of 1920's, designed by Le Corbusier were analysed. The Le Corbusier's proportional system can be classified by two different purposes ; aesthetics and utility standardization for the mass production was reflected. In the later period, the proportion system of 1920's has changed through the process of self-contradiction. But the concept of the golden section and the human scale was reflected on Modulor, which Le Corbusier created in 1940's. Therefore, Le Corbuiser's notion of proportion for harmony of architecture has consistent meaning throughout all of his works from the 1920's.

• Journal of KIISE:Software and Applications
• /
• v.30 no.1_2
• /
• pp.103-116
• /
• 2003

States explosion due to composition of spaces of data, temporal, and locational values is one of the well-known critical problems which cause difficulty in understanding and analysing real-time systems specified with state-based formal methods. In order to overcome this problem, this paper presents an abstraction method for state minimization based on an abstraction in system specification and an abstraction in system execution. The first is named the syntactic in system specification and an abstraction in system execution. The first is named the syntactic abstraction, through which the patterns of the unconditionally internalized computation and the repetition and selection structures are abstracted. The latter is named the semantic abstraction, through which the patterns of the execution space represented with data. Through the abstractions, the components of a system in specification and execution model is hierarchically organized. The system can be analyzed briefly in the upper level in an skeleton manner with low complexity. The system, however, can be abstraction method for the state minimization and the decrease in analysis complexity through the abstraction with examples.

• Journal of Institute of Control, Robotics and Systems
• /
• v.3 no.1
• /
• pp.46-51
• /
• 1997

The optimal control of a continuous process has been performed using genetic algorithms(GAs). GAs are robust and easily applicable for complex and highly nonlinear problems. We introduce the heuristics 'dynamic range' which reduces the search space dramaticaly keeping the robust search of GAs. GAs with dynamic range show the better performance than SQP(Successive Quadratic Programing) method which converges to a local minimum. The proposed methology has been applied to the optimal control of the continuous MMA-VA copolymerization reactor for the production of the desired molecular wieght and the composition of VA in dead copolymer.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.34 no.11
• /
• pp.113-123
• /
• 2018

First of all, the multi-story Housing applying resident's participation in europe was classified by the menu selection method, the two-step supply method and the cooperative method. And then I analyzed flexible unit plan of cases for deriving the planning methode and the characteristics of flexibility. First, I analyzed the area and form of the unit plan, structure and Installation, fixed and variable elements to derive the planning method. The area of units are distributed from a minimum of $35m^2$ to a maximum of $150m^2$, and many of the unit planes have a narrow front and a deep depth. The structure is a long-span wall-structure or a skeleton structure, and is designed without any columns and bearing walls in the interior space for flexibility in spatial composition. The vertical shafts are located in the center of the unit in a box-form or in the corner at the unit dividing wall for free placement of interior wall. Fixed elements are framework and facility systems. Most of the future residents in the two-steps supply method and the cooperative method were able to freely design the internal space within the zoning concept proposed by the architect and change the location of the facade element within module system proposed by the architect. Second, the characteristics of the flexibility applied to the unit plan were divided in integrated flexibility, functional flexibility, construction flexibility, and supply flexibility. The integrated flexibility enables residents to give the variable space combination based on the complex structure of the inner space for providing various living experiences. Regarding functional flexibility, the three-dimensional spatial structure with neutral space has multi-functionality according to the needs of residents and easily accepts mixing of hybrid programs such as work and residence. Constructive flexibility allows residents to create identity by freely planning interior space and changing the size or location of facade components in a determined system of architects. Finally, various types of size and space composition are proposed and realized in the whole building applying menu selection method, so that flexibility in the offer can accommodate and integrate various types of living.

• Journal of Intelligence and Information Systems
• /
• v.7 no.1
• /
• pp.149-159
• /
• 2001

There have been lots of researches for providing a personalized service to a customer using one-to-one marketing and collaborative filtering techniques in E-Commerce. However, there are technical difficulties for providing the recommendation of products far users, which often involve high complexity of computation. In this paper, we have presented an integrated method of classification problem solving method and constraint based configuration techniques. This method can reduce a complexity of computation by classifying a solution domain space that has a higher complexity of composition. Thereafter, we have modeled customers constraints and the components of products to configure a complete system by passing it to constraint processing module in Constraint Satisfaction Problems. Constraint-based configuration uses the constraint propagation using the constraints of buyers and the constraints among PC components to configure a proper product for a customer. We have transformed and applied vector space modeling method in the field of information retrieval to consider a customer satisfaction in addition to the CSP. Finally, we have applied our system to test data fur evaluating a customers satisfaction and performance of the proposed system.

• Computers and Concrete
• /
• v.3 no.5
• /
• pp.301-312
• /
• 2006

Experimental research revealed that the spatial dispersion of aggregate grains exerts pronounced influences on the mechanical and durability properties of concrete. Therefore, insight into this phenomenon is of paramount importance. Experimental approaches do not provide direct access to three-dimensional spacing information in concrete, however. Contrarily, simulation approaches are mostly deficient in generating packing systems of aggregate grains with sufficient density. This paper therefore employs a dynamic simulation system (with the acronym SPACE), allowing the generation of dense random packing of grains, representative for concrete aggregates. This paper studies by means of SPACE packing structures of aggregates with a Fuller type of size distribution, generally accepted as a suitable approximation for actual aggregate systems. Mean free spacing $\bar{\lambda}$, mean nearest neighbour distance (NND) between grain centres $\bar{\Delta}_3$, and the probability density function of ${\Delta}_3$ are used to characterize the spatial dispersion of aggregate grains in model concretes. Influences on these spacing parameters are studied of volume fraction and the size range of aggregate grains. The values of these descriptors are estimated by means of stereological tools, whereupon the calculation results are compared with measurements. The simulation results indicate that the size range of aggregate grains has a more pronounced influence on the spacing parameters than exerted by the volume fraction of aggregate. At relatively high volume density of aggregates, as met in the present cases, theoretical and experimental values are found quite similar. The mean free spacing is known to be independent of the actual dispersion characteristics (Underwood 1968); it is a structural parameter governed by material composition. Moreover, scatter of the mean free spacing among the serial sections of the model concrete in the simulation study is relatively small, demonstrating the sample size to be representative for composition homogeneity of aggregate grains. The distribution of ${\Delta}_3$ observed in this study is markedly skew, indicating a concentration of relatively small values of ${\Delta}_3$. The estimate of the size of the representative volume element (RVE) for configuration homogeneity based on NND exceeds by one order of magnitude the estimate for structure-insensitive properties. This is in accordance with predictions of Brown (1965) for composition and configuration homogeneity (corresponding to structure-insensitive and structure-sensitive properties) of conglomerates.