• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.9-14
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• 2006

This study presented the feasibility of R152a refrigerant as an alternative of R134a which is used in the current automobile air conditioning system. The performance of air conditioning system installed in the actual vehicle was tested using the climate wind tunnel. The experiments were conducted at various refrigerant charge quantities and various driving conditions such as city traffic, highway traffic and parking. Same components and lubricant were used for both R134a and R152a system. The effects of air set values of thermal expansion valve on the performance were also investigated. In case of the R152a system, refrigerant charge quantity can be reduced about 20%, better performance and superior compressor durability is expected due to the lower discharge pressure compared to the R134a system.

• The korean journal of orthodontics
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• v.49 no.2
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• pp.116-123
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• 2019

As an alternative to the conventional fixed appliance that uses orthodontic brackets, a simple round tube without a bonding base can be bonded to the tooth surface by covering the tube with flowable resin. In this technique, bent wires cannot be inserted into the simple tubes; therefore, repositioning of the simple tubes is often required for adjustments. To reduce repositioning of simple tubes, a dome-shaped resin covering of the simple tube can be designed with a customized in-and-out compensation, using three-dimensional computer-aided design software based on digital simulation of orthodontic tooth movement. In the present case, the use of simple tubes bonded with customized resin coverings in a Class I nonextraction case is described in a 17-year-old male, in whom moderate crowding of the anterior teeth was treated over an 8-month period. This case shows that simple tubes can be used as an alternative to brackets in some Class I nonextraction cases, with the potential benefit of reducing decalcification.

• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.219-230
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• 2021

International seismic codes stipulate that adjacent buildings should be separated by a specified minimum distance, otherwise the pounding effect should be considered in the design. Recent researches proposed an alternative method (Double Difference Combination Rule) to estimate seismic gap between structures, as this method considers the cross relation of adjacent buildings behavior during earthquakes. Four different criteria were used to calculate the minimum separation distance using this method and results are compared to the international codes for five separation cases. These cases used four case study buildings classified by different heights, lateral load resisting systems and fundamental periods of vibrations to assess the consistency in results for the alternative methods. Non-linear analysis was performed to calculate the inelastic displacements of the four buildings, and the results were used to evaluate the relation between elastic and inelastic displacements due to the ductility of structural elements resisting seismic loads. A verification analysis was conducted to guarantee that the separation distance calculated is sufficient to avoid pounding. Results shows that the use of two out of the four studied methods yields separation distances smaller than that calculated by the code specified equations without under-estimating the minimum separation distance required to avoid pounding.

• Journal of Urban Science
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• v.12 no.2
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• pp.19-30
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• 2023

The seismic design of water tanks for fire protection is important to prevent secondary earthquake damages due to fires. In this study, the seismic performance of stainless steel water tanks was evaluated considering both static and dynamic water pressure effects, and the influence of different panel shapes was investigated through numerical analysis. First, a basic water tank model comprised of flat panels was built, and then water pressure distribution including sloshing effects was evaluated. In the result of structural analysis, many panels of the basic water tank exceeded a specified allowable stress for load combinations including earthquake loads. In order to reduce the bending stress of the panel by increasing the moment of inertial of the panel section, alternative shapes of a truncated quadrangular pyramid were developed. Five water tanks with different alternative panel shapes were built and analyzed for the same load combinations. Based on the results of the numerical analysis, a number of effective aspect ratios were selected and modified to increase economic feasibility through additional analysis and structural safety check.

• Journal of the Korean housing association
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• v.20 no.1
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• pp.45-58
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• 2009

This research starts from the questioning of current housing development on the hilly site in Korea. It aims to investigate various design techniques of low-rise housing as an alternative housing plan on hilly sites. Several generic solutions of the combination of building type and road pattern are tested for a simulation process, and evaluated in terms of crucial design issues; development density, parking space and open space. As a result, four reasonable models are selected for making full use of geographical features of hilly site, two models each land slope of $18^{\circ}$ and $26^{\circ}$. Several design techniques for each model are also suggested, in ensuring the development feasibility by considering land slope, vehicular access and parking, common open space, and community facilities.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1743-1753
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• 2011

Seoul Metropolitan Government has performed alternative transit system, light rail transit(LRT), for settling the problems of urban public transit system based on conventional bus service and heavy rail transit(HRT). LRT projects of total 8 lines(about 73.6km), including Ui-Sinseol line, have been planned as Build-Transfer-Operate(BTO) projects. For the first LRT, Ui-Sinseol line, however, design of structure had met standard for design of HRT, because of no domestic design code for LRT when participates of Ui-Sinseol project submitted the design proposal. This case study reports a successful example of LRT design minimizing the scale of stations designed in base of HRT code. The problems, like oversized structures compared with LRT vehicles, excessive costs for construction, had been resolved through negotiations with the participates of Ui-Sinseol line. Result suggests that present and future costs for construction and maintenance of the LRT projects in Seoul be considerably reduced in advance.

• Wind and Structures
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• v.9 no.4
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• pp.331-344
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• 2006

The cable-stayed-suspension hybrid bridge is a cooperative system developed from the traditional cable-stayed and suspension bridges, and takes some advantages of the two bridge systems. It is also becoming a competitive design alternative for some long and super long-span bridges. But due to its great flexibility, the flutter stability plays an important role in the design and construction of this bridge system. Considering the geometric nonlinearity of bridge structures and the effects of nonlinear wind-structure interaction, method and its solution procedure of three-dimensional nonlinear flutter stability analysis are firstly presented. Parametric analyses on the flutter stability of a cable-stayed-suspension hybrid bridge with main span of 1400 meters are then conducted by nonlinear flutter stability analysis, some design parameters that significantly influence the flutter stability are pointed out, and the favorable structural system of the bridge is also discussed based on the wind stability.

• Steel and Composite Structures
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• v.3 no.6
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• pp.451-474
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• 2003

Details are given of a cold-formed steel portal framing system that uses simple bolted moment-connections for both the eaves and apex joints. However, such joints function as semi-rigid and, as a result, the design of the proposed system will be dominated by serviceability requirements. While serviceability is a mandatory design requirement, actual deflection limits for portal frames are not prescribed in many of the national standards. In this paper, a review of the design constraints that have an effect on deflection limits is discussed, and rational values appropriate for use with cold-formed steel portal frames are recommended. Adopting these deflection limits, it is shown through a design example how a cold-formed steel portal frame having semi-rigid eaves and apex joints can be a feasible alternative to rigid-jointed frames in appropriate circumstances.

• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.325-335
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• 2003

Robust design is to identify appropriate settings of control factors that make the system's performance robust to to changes in the noise factors that represent the source of variation. In the Taguchi parameter design, the product array approach using orthogonal arrays is mainly used. However, it often requires an excessive number of experiments. An alternative approach, which is called the combined array approach, was suggested by Welch et. al. (1990) and studied by others. In these studies, only single response variable was considered. We propose how to simultaneously optimize multiple responses when we use the combined array approach.

• Journal of the Korea Institute of Building Construction
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• v.2 no.2
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• pp.157-164
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• 2002

In this study, attempts to analyze the case study of production design were carried out through: 1) exploration of the factors influencing the interface between architectural and production design phases; 2)application of precast technologies. Building design and construction planning in Japan may be characterized by ample use of Production Design which extends over the whole projects phases. Taking a composite construction system for apartment buildings which allow for alternative combination of different technologies as a case study object, three projects have been chosen to analyze actual process of determining product sub-system and their specification. And the expectancies of this paper are that it can be used as efficient data for improvement of system to systematize Constructability(Buildability) in korea.