• Journal of the Korean Mathematical Society
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• v.44 no.5
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• pp.1121-1137
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• 2007

There are 7 types of 4-dimensional solvable Lie groups of the form ${\mathbb{R}^3}\;{\times}_{\varphi}\;{\mathbb{R}}$ which are unimodular and of type (R). They will have left. invariant Riemannian metrics with maximal symmetries. Among them, three nilpotent groups $({\mathbb{R}^4},\;Nil^3\;{\times}\;{\mathbb{R}\;and\;Nil^4)$ are well known to have lattices. All the compact forms modeled on the remaining four solvable groups $Sol^3\;{\times}\;{\mathbb{R}},\;Sol_0^4,\;Sol_0^'4\;and\;Sol_{\lambda}^4$ are characterized: (1) $Sol^3\;{\times}\;{\mathbb{R}}$ has lattices. For each lattice, there are infra-solvmanifolds with holonomy groups 1, ${\mathbb{Z}}_2\;or\;{\mathbb{Z}}_4$. (2) Only some of $Sol_{\lambda}^4$, called $Sol_{m,n}^4$, have lattices with no non-trivial infra-solvmanifolds. (3) $Sol_0^{'4}$ does not have a lattice nor a compact form. (4) $Sol_0^4$ does not have a lattice, but has infinitely many compact forms. Thus the first Bieberbach theorem fails on $Sol_0^4$. This is the lowest dimensional such example. None of these compact forms has non-trivial infra-solvmanifolds.

• Journal of the Korean housing association
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• v.27 no.6
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• pp.105-112
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• 2016

Although smart homes have been much developed in China, smart homes has been mainly towards the adoption of new technologies. There is little development of smart homes to consider and meet residents' needs in China. This study investigated residents' living in apartments in China using a questionnaire to identify their demands on smart homes. Through the survey, this study analyzed residents' space use patterns, daily living patterns etc. according to their ages. The results implied that there are significant differences in the use of spaces and demands on daily living within apartments. The results of this study should be considered for the development of smart homes in future. For example, it might be easier for people in the 20's to adopt Internet of Things (IoT) and environmental control systems compared to other age groups because most of them in the 20's use smart phones effectively without difficulties. In case of people in their 50's who stay home more times for taking a rest and eating meals compared to other age groups, smart technologies should be applied to support their health care and works in housings. This research emphasizing residents' experiences could be basis for the development of smart homes in China.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.454-461
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• 2010

The new SOLAS regulation permits the alternative design approach for the approval of designs which deviate from those where prescriptive rules apply. The new approach is being promoted by recent advances of noble designs such as those employing large public spaces in passenger ships. From the respect of fire safety, it is needed to show that the level of safety of new design is equivalent to what can be achieved from the prescriptive rules where the fire simulation is regarded to be the essential tool. This paper provides an overview of the process of performance-based design of the smoke extraction system in a cafeteria of a ROPAX. FDS, a CFD fire simulation software is used to show that the field-model software can improve the fire safety over what are expected from prescriptive rule sets or zone-model application.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2173-2180
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• 1995

This paper presents free vibration analysis method using the characteristics of the rotationally periodic structures and includes the analysis results of a tire as an example. The normal modes of the rotationally periodic structures are the kind of standing waves, so all sectors have the same deflection shapes, and only different phases. This property makes it possible to derive the analysis method called sector method. The sector method can give the accurate natural frequencies and the corresponding mode shapes of the rotationally periodic structure with information of only one sector. When the free vibration analysis is performed to find the dynamic characteristics of the rotationally periodic structure by using the sector method, the computer memory spaces and the CPU times can be saved. We obtained much economic benefits by using the sector method in the analysis of dynamic characteristics of a tire made of non-linear materials.

• Korean Institute of Interior Design Journal
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• v.22 no.2
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• pp.89-99
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• 2013

The comtemporary architecture has not an discourse on form and representative style, but a new architectural concept of the generative process through the various relationship of the urban context, the continuity of the time and the experience of the people. This architectureal concepts make new and various architectural attempts to have a virtuality. The viruality is a reality to coexist with the present in contemporary philosophy. Daniel libeskind makes various arhcitectural experimentative attempts to reveal his virtuality through his memory as the Jews and his unconscious virtuality. The 'line' has the connotation of architectural reality and virtuality. Every line drawn becomes architectural form for example, walls, windows and makes spaces, and reveal a boundary as a connection. Architecture's visibility understates and structures its invisible aspect, so that the visible and the invisible make the architecture together. Daniel libeskind maks the virtual lines having the invisible of unconsious, time, and place. He no longer divide the form of architecture, its spatiality from all the implications which it adresses beyond its own particular built time and place and public unconsious mind. He demands the 'virtual line' that remembers distress and the past and reveal the virtuality of time and place. The virtual line is the sentimental communication of architecture.

• Structural Engineering and Mechanics
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• v.3 no.4
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• pp.373-382
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• 1995

The weighting strategy has received a great attention and has been widely applied to multicriterion optimization. This gaper examines a global criterion method (GCM) with the weighting objectives strategy in fuzzy structural engineering problems. Fuzziness of those problems are in their design goals, constraints and variables. Most of the constraints are originated from analysis of engineering mechanics. The GCM is verified to be equivalent to fuzzy goal programming via a truss design. Continued and mixed discrete variable spaces are presented and examined using a fuzzy global criterion method (FGCM). In the design process a weighting parameter with fuzzy information is introduced into the design and decision making. We use a uniform machine-tool spindle as an illustrative example in continuous design space. Fuzzy multicriterion optimization in mixed design space is illustrated by the design of mechanical spring stacks. Results show that weighting strategy in FGCM can generate both the best compromise solution and a set of Pareto solutions in fuzzy environment. Weighting technique with fuzziness provides a more relaxed design domain, which increases the satisfying degree of a compromise solution or improves the final design.

• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.31-44
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• 2009

While the classical theory of Griffith is the foundation of modern understanding of brittle fracture, it has a number of significant shortcomings: Griffith theory does not predict crack initiation and path and it suffers from the presence of unphysical stress singularities. In 1998, Francfort and Marigo presented an energy functional minimization method, where the crack (or its absence) as well as its path are part of the problem's solution. The energy functionals act on spaces of functions of bounded variations, where the cracks are related to the discontinuity sets of such functions. The new model presented here uses modified energy functionals to account for molecular interactions in the vicinity of crack tips, resulting in Barenblatt cohesive forces, such that the model becomes free of stress singularities. This is done in a physically consistent way using recently published concepts of Sinclair. Here, for the consistency of the model, it becomes necessary to allow for crack reversibility and to consider local minimizers of the energy functionals. The latter is achieved by introducing different time scales. The model is solved in its global as well as in its local version for a simple one-dimensional example, showing that local minimization is necessary to yield a physically reasonable result.

• Journal of architectural history
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• v.1 no.2 s.2
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• pp.172-182
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• 1992

The binary classification, Yin & Yang, can be shown in our culture. Yin & Yang thinking reveals the Up/Down (Principal/Subordinate) relation in space, and Before/After relation in time, and it shows the sequence of Contrast${\to}$Reconciliation & Unification${\to}$Contrast. For example, a follower is Yin against King, while Yang as a father against his son in our trational cognitive structure. With Left/Right, Front/Rear, and Upper/Lower, In/Out division is a basic body-space term to grasp the space position. In the traditional Korean house, when we go out from the deepest 'In', Anbang to Daechung, we may call Anbang 'In' and Daechung 'Out'. When from Daechung to Anmadang reversely, we call Daechung 'In' and Anmadang 'Out'. Namely, Daechung is both 'In' and 'Out'. This is a fallacy logic in view of western basic conception. 'The In/Out Structure, system of a series of inner spaces, is defined as a transformation of cognitive structure of Yin & Yang thinking to the Korean architectural space. The space structure is one of the important deep structure in Korean society.' The concept of the space structure, apperred in east Asia, can make humane space, for it is not a physical 'type' of typepology but related to cognitive structure of human thinking, The structure is applicable to space design in modern society, for the cognitive structure exists in living culture by transformation.

• Journal of applied mathematics & informatics
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• v.19 no.1_2
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• pp.397-414
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• 2005

In the existing literature, most of the purchasing models were developed only for retailers problem ignoring the constraint of storage capacity of retailers shop/showroom. In this paper, we have developed a deterministic model of wholesaler-retailers' problem of single product. The storage capacity of wholesaler's warehouse/showroom and retailers' showroom/shop are assumed to be finite. The items are transported from wholesaler's warehouse to retailers' Own Warehouse (OW) in a lot. The customer's demand is assumed to be displayed inventory level dependent. Demands are met from OW and that spaces of OW will immediately be filled by shifting the same amount from the Rented Warehouse (RW) till the RW is empty. The time duration between selling from OW and filling up its space by new ones from RW is negligible. According to relative size of the retailers' existing (own) warehouse capacity and the demand factors, different scenarios are identified. Our objectives are to optimize the cost functions of wholesaler and two retailers separately. To solve this problem, a real coded Genetic Algorithm (GA) with roulette wheel selection/reproduction, whole arithmetic crossover and non-uniform mutation is developed. Finally a numerical example is presented to illustrate the results for different scenarios. To compare the results of GA, Generalised Reduced Gradient Method has been used for the problem. Also, a sensitivity analysis has been performed to study the variations of the optimal average cost with respect to the different parameters.

• Korean Institute of Interior Design Journal
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• v.22 no.5
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• pp.68-77
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• 2013

'The Third space,' which is the concept that embraces sociological, spatial, and marketing concepts, refers to the place which is other than the home and the workplace and which is a comfortable frequented place where meditation, psychological relaxation, and social needs can be satisfied. 'The Third space' has the characteristics of comfort, openness, interactivity, playfulness, and diversity. In modern times, most of consumption spaces play the role of 'the Third space,' and the typical example is $Caf{\acute{e}}$. $Caf{\acute{e}}$ began from its origin with the characteristics of 'the Third space,' and recently it has become the complex cultural space of urban dwellers. $Caf{\acute{e}}$ as 'the Third space' has the characteristics of a healing space, communication space, personalized space, value-expressive space, culture and consumption space, nomad space. Such characteristics of $Caf{\acute{e}}$ are well represented in the cafes around the regions where 'street culture' has recently been formed. As examined through the examples, $Caf{\acute{e}}$ as 'the Third space' can be more strategically produced by establishing themes through storytelling, giving spatial identity through style creation, diversifying the sequence through complex space organization, and establishing interaction devices through experience elements.