• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.6
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• pp.84-92
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• 2005

This paper is concerned with optimum design of a center-pillar assembly induced by the high-speed side impact of the vehicle. In order to simulate deformation behavior of the center-pillar assembly, simplified finite element model of the center-pillar and a moving deformable barrier are developed based on results of the crash analysis of a full vehicle model. In optimization of the deformation shape of the center-pillar, S-shaped deformation is targeted to guarantee reduction of the injury level of a driver dummy in the crash test. Tailor-welded blanks are adopted in the simplified center-pillar model to control the deformation shape of the center-pillar assembly. The thickness of each part which constitutes the simplified model is selected as a design parameter. The thickness of parts which have significant effect on the deformation mechanism are selected as design parameters with sensitivity analysis based on the design of experiment technique. The objective function is constructed so as to minimize the weight and lead to an S-mode deformation shape. The result shows that the simplified model can be utilized effectively for optimum design of the center-pillar members with remarkable saving of computing time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.716-718
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• 2012

This paper have presented the change for subthreshold characteristics for double gate(DG) MOSFET based on scaling theory and the shape of Gaussian function. To obtain the analytical solution of Poisson's equation, Gaussian function been used as carrier distribution and consequently potential distributions have been analyzed closely for experimental results, and the subthreshold characteristics have been analyzed for the shape parameters of Gaussian function such as projected range and standard projected deviation. Since this potential model has been verified in the previous papers, we have used this model to analyze the subthreshold chatacteristics. The scaling theory is to sustain constant outputs for the change of device parameters. As a result to apply the scaling theory for DGMOSFET, we know the subthreshold characteristics have been greatly changed, and the change of threshold voltage is bigger relatively.

• Structural Engineering and Mechanics
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• v.55 no.3
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• pp.555-581
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• 2015

Triangular pyramid and Quadrangular pyramid elements for partial double-layer spherical reticulated shells of pyramidal system are investigated in the present study. Macro programs for six typical partial double-layer spherical reticulated shells of pyramidal system are compiled by using the ANSYS Parametric Design Language (APDL). Internal force analysis of six spherical reticulated shells is carried out. Distribution regularity of the stress and displacement are studied. A shape optimization program is proposed by adopting the sequence two-stage algorithm (RDQA) in FORTRAN environment based on the characteristics of partial double-layer spherical reticulated shells of pyramidal system and the ideas of discrete variable optimization design. Shape optimization is achieved by considering the objective function of the minimum total steel consumption, global and locality constraints. The shape optimization of six spherical reticulated shells is calculated with the span of 30m~120m and rise to span ratio of 1/7~1/3. The variations of the total steel consumption along with the span and rise to span ratio are discussed with contrast to the results of shape optimization. The optimal combination of main design parameters for six spherical reticulated shells is investigated, i.e., the number of the optimal grids. The results show that: (1) The Kiewitt and Geodesic partial double-layer spherical reticulated shells of triangular pyramidal system should be preferentially adopted in large and medium-span structures. The range of rise to span ratio is from 1/6 to 1/5. (2) The Ribbed and Schwedler partial double-layer spherical reticulated shells of quadrangular pyramidal system should be preferentially adopted in small-span structures. The rise to span ratio should be 1/4. (3) Grids of the six spherical reticulated shells can be optimized after shape optimization and the total steel consumption is optimized to be the least.

• Korean Institute of Interior Design Journal
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• v.20 no.5
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• pp.13-22
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• 2011

The purpose of this study is to analyze Alva Aalto's libraries for understanding his efficient induction of natural light. To fulfill this purpose, Alvar Aalto's thought about library and natural light are examined through his working years and building types. The comparison of his libraries on usage of natural light shows different ways of natural light induction based on different locations and programs of libraries. Similarities and differences of Alvar Aalto's library architecture have strong relationship to the usage of natural light in libraries because Alvar Aalto himself regard reading as the core function of library and the efficient use of natural light is the main key of reading. In his natural light planning, regional characteristics including environmental factors and programmatic differences act as a basic standard for natural light plan. Especially, altitude of sun and its path, seasonal features affect the induction way of natural light. While conical skylights used at Viipuri library shows the characteristics of universality in Modernism architecture, later libraries presents not only various kinds of pan-shape plan but different ways of inducing natural light in according to appropriate function. From conical skylight to monitor with curved reflection wall make it possible shed diffused light to reading space and this affects to form Alvar Aalto's organic architecture. As a result, using natural light in Alvar Aalto's library architecture act as the core of forming library concepts and their development.

• Journal of the Korean housing association
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• v.17 no.5
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• pp.87-95
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• 2006

Building components have been deteriorated by various factors such as location, a building type, a surrounding environment and so on. In addition, each component has a peculiar characteristics, compared with other components in properties of matter an used part. Building components would be required to maintain its function and performance to provide the resident with a decent living condition. It is important to decide the repair time, scope and a required cost in repair plan, considering the each component's characteristics. In this parer, it aimed at providing the economic repair pattern to analyze the relation of the time-elapse and the cumulative repair cost in the apartment housing using 3rd quadratic function. Results of the study are as follows: First, the shape of the function for the economic repair is classified into two type. One is the continuous increase type of the cumulative cost which properly means the iterative repair type after built. The other is that the function has the maximum state at a point which means one-repair after its repair would be delayed to a scheduled time. Second, the iterative repair pattern would include window, roof proof, lighting and water supply pipe. The other repair pattern would include the paintings, heating pipe and sign board.

• Journal of KIEE
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• v.11 no.1
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• pp.14-20
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• 2001

To design a controller based on the pole placement method, it is necessary to obtain either a target transfer function or a desired characteristic equation which results in the closed-loop response. Specially, a step response in which no overshoot occurs in highly desirable in many applications. In this paper, we present two new present two new prototypes of Type I target transfer functions whose step responses have an overshoot of less than 0.1%. One prototype is obtained by Taylor's approximation of a Gaussian function. It is, however, observed that the response delays increase with increasing order, while the rise times are nearly constant. The other prototype is a modification of the first prototype, so that their transfer function coefficients have particular values in terms of specific parameters ${\gamma}$i and $\tau$ (see section 2). The second prototype gives very useful properties in which step responses are almost the same shape, irrespective of the order. It, also, has no overshoot. Some other properties of the prototypes and an application example are given.

• Wind and Structures
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• v.16 no.2
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• pp.157-178
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• 2013

Output-only modal parameter identification is based on the assumption that external forces on a linear structure are white noise. However, harmonic excitations are also often present in real structural vibrations. In particular, it has been realized that the use of forced acceleration responses without knowledge of external forces can pose a problem in the modal parameter identification, because an external force is imparted to its impulse acceleration response function. This paper provides a three-stage identification procedure as a solution to the problem of harmonic and white noise excitations in the acceleration responses of a linear dynamic system. This procedure combines the uses of the mode indicator function, the complex mode indication function, the enhanced frequency response function, an iterative rational fraction polynomial method and mode shape inspection for the correlation-related functions of the force-embedded acceleration responses. The procedure is verified via numerical simulation of a five-floor shear building and a two-dimensional frame and also applied to ambient vibration data of a large-span roof structure. Results show that the modal parameters of these dynamic systems can be satisfactorily identified under the requirement of wide separation between vibration modes and harmonic excitations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1B
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• pp.47-55
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• 2011

This study suggests new synthetic unit hydrograph method considering hydrodynamic characteristic on the basin. The suggested method based on width function GIUH, and the procedure is summarized as follows; 1) Draw up a travel distance distribution map (width function) which is raster of length between from center of individual cells to the outlet by GIS. 2) Calculation of travel time distribution map (rescaled width function) by hydrodynamic parameters and travel distance distribution map. 3) Derivation of IUH and Duration UH from rescaled width function. 4) Comparison of shape of UH between suggested method and existing synthetic unit hydrograph methods. The target basins are selected Ipyeong and Tanbu subwatershed in the Bocheong Basin. The target basins are similar scale (watershed area), but different drainage structure (drainage density et al.). Therefore we anticipate that there are different hydrologic response functions because different hydrodynamic characteristics. As a result of derivation of UH, existing synthetic unit hydrograph methods are similar shape of UHs about Ipyeong and Tanbu watersheds, but the suggested method is different shape of ones. As a result of application to observed data, the peak discharge by suggested method is similar to existing synthetic unit hydrograph methods, but the peak time is well correspondence between those. Henceforth, if the suggested method combines with the rational velocity estimation method, it is useful method for synthetic of UH in ungauged watershed.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.644-658
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• 2021

Understanding the functional traits of dominant species in urban ecosystems provides insight into species' trait adaptation and ecosystem function in response to fragmented and isolated urban vegetation and reduced biological interactions. This study compared means and variances of environmental factors (geographic, meteorological, and soil attributes) and 4 leaf traits (leaf area, specific leaf area, leaf dry mass content, and leaf shape index) and 7 reproductive traits (fruit width, fruit length, fruit shape, fruit dry weight, fruit dry matter content, seed weight, and seed ratio) measured of 40 Sorbus alnifolia individuals in four mountainous areas south of Seoul downtown, South Korea. We then performed the multivariate analysis of trait combinations. While the measured environmental factors indicated the individuality of the survey sites, the urban vegetation was drier and had a longer growth period. The leaves of S. alnifolia in the urban areas were smaller and heavier, and the fruits produced longer and lighter seeds, showing the traits affected by long urbanization. The study confirmed changes in the growth and reproduction mechanism of the S. alnifolia population under the urban environment, indicating reduced biological interaction due to vegetation fragmentation and isolation. This study provides limited but distinct ecological information about the function and persistence of key species in cities with a reduced scale of biological interactions and many negative environmental factors such as air pollution.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.319-330
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• 2002

A toe spring and ball girth data, when marathone shoes research, development, and production in Korea, is a important point in athlete shoe research. It is clear from the results presented that any differences between MA3 and MA1, MA4 in 70%, 80% session in forepart last comparision. Especially the more 70%-80% session getting wide, the more 90% session getting up, Also, To development for high performance marathones shoes last, in all session, in korean style, 70%, 80%, and 90% session part function changed and consequently there is a need for normative last data that desribe foot, last shape, dimension. this leads to the conclusion that unique shoe lasts for both marathone shoes developmented last comparison are required for optimal marathone shoe comfort. The more ball girth construction will wide in forepart in last, the more comfort characteristic sill development. But relative with performance ability, it is need to research. The further study of Korea marathoner forefoot measurements(70% session ~ 90% session) among toe spring's angular difference of marathone last to north american and Korea marathone shoes last is required to develop and improve athletes performance in an effective way of study and to prevent forefoot injury.