• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.350-358
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• 2014

The demand for the lightweight wall has increased as the structure of the multi-unit dwelling has shift to the rahmen structure. The lightweight wall is required to secure certain degree of shock resistance for the structural safety. The study performed the load analysis test for 7 small hard bodies with different masses and shapes and 5 hard materials which applied the impact load on the wall. It was found out from the experiment that different pendulum weight doubled the load maximum even though the shock energy was the same. In addition, the study compared and analyzed the weight of materials and the load of small hard bodies to propose fundamental data for the material design of the lightweight wall.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.4
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• pp.482-490
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• 2013

This study suggests a suitable logo design application of a three colors LED light source and flexible plastic optical fiber (POF). In this study, characteristic relevant brightness of (according to the embodiment conditions of the flexible POF for logo design) for smart clothing were analyzed through two experiments. The suitable conditions of the logo design for three colors of light source were observed in 'Experiment 1'. The angle of $80^{\circ}$ to $100^{\circ}$ and the length of 8cm to 16cm appeared a more suitable condition for green-colored and red-colored light sources. The angle of $80^{\circ}$ to $100^{\circ}$ at a length of 8cm to 12cm appeared a more suitable condition for a blue-colored light source. In 'Experiment 2', a 'Klavika' in small letter was selected as suitable logo design for the application POF. The alphabet was separated by a morpheme, which is the minimal linguistic unit. All alphabets were classified into sixteen morphemes. The luminance of fourteen morphemes (realized by the embroidery method) were measured and analyzed. Subsequently, eight morphemes appeared to show a relatively equal luminance of $3-4cd/m^2$ in a green-colored light source, $2-3cd/m^2$ in red-colored light source, and $2cd/m^2$ in a blue-colored light source. Four of the fourteen morphemes, showed a 20% brighter level of luminance compared to the eight morphemes above, the cast of combination of green or red light source. This result indicates that a flexible POF with 20% less luminance are believed more suitable for four morphemes combined with a green or red light source. The results of this study provide fundamental data for further approaches to clothing logo design for the application of a flexible POF.

• Steel and Composite Structures
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• v.21 no.5
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• pp.1031-1043
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• 2016

Optimization of the construction scheme of the cable-strut tensile structure based on error sensitivity analysis is studied in this paper. First, the element length was extracted as a fundamental variable, and the relationship between element length change and element internal force was established. By setting all pre-stresses in active cables to zero, the equation between the pre-stress deviation in the passive cables and the element length error was obtained to analyze and evaluate the error effects under different construction schemes. Afterwards, based on the probability statistics theory, the mathematical model of element length error is set up. The statistical features of the pre-stress deviation were achieved. Finally, a cable-strut tensile structure model with a diameter of 5.0 m was fabricated. The element length errors are simulated by adjusting the element length, and each member in one symmetrical unit was elongated by 3 mm to explore the error sensitivity of each type of element. The numerical analysis of error sensitivity was also carried out by the FEA model in ANSYS software, where the element length change was simulated by implementing appropriate temperature changes. The theoretical analysis and experimental results both indicated that different elements had different error sensitivities. Likewise, different construction schemes had different construction precisions, and the optimal construction scheme should be chosen for the real construction projects to achieve lower error effects, lower cost and greater convenience.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.128-133
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• 2005

In this study, performance design programs for components of a turbopump unit (TPU) in a Liquid Rocket Engine (LRE), that has non-cryogenic centrifugal pumps and 1-stage impulse turbine with partial admission nozzle, were developed. The programs were integrated in a TPU module by balancing the mass flow rate for pump-turbine power, and the module was inserted into the LRE system conceptual design program. The fundamental design conditions, satisfying LRE system requirements and minimum mass flow rate condition of gasgenerator, were found and compared with data from a Russian liquid rocket engine.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.303-310
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• 2004

The purpose of this study was to investigate the effect of using method and replacement ratio of limestone powder and water-cement ratio on the compressive strength and the resistance to sulfate attack of mortar incorporating limestone powder as fundamental study to use limestone powder as an addition for concrete. As a results, The method using limestone powder as a part of cement showed decrease of the compressive strength of mortar. The strength of mortar incorporating limestone powder almost decided upon unit cement content. It was recognized that the method replacing limestone powder as a part of cement was effective to decrease the heat of hydration in concrete. The method using limestone powder as a part of fine aggregate showed the considerable increase of the strength and resistance to sulfate attack of concrete. Furthermore, it was recognized that the method using limestone powder as a part of fine aggregate were effective materials as an addition for concrete in view of the improvement of strength and resistance to sulfate attack.

• Journal of the Korea Institute of Building Construction
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• v.7 no.1 s.23
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• pp.115-121
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• 2007

Ordinary concrete uses aggregate sufficiently soaked with water, and is weighed, mixed with other materials and placed in accord with performances required in the construction field. Recently special concrete with high fluidity and durability is required but it is difficult to use top-quality concrete due to lack of high-quality aggregate, delayed transportation because of traffic jam, etc. In addition, sometimes the use of a remicon is inevitable just for small-sized concrete constructions or it is difficult for a remicon to reach remote construction places such as mountainous areas. To solve these problems, this study attempted to pack concrete materials. In other words, it is to instantize concrete. This study dried aggregate, a material of concrete, and compared the change of absorption phase of the aggregate in water and in paste in order to examine the effect of the dryness of aggregate on its absorption rate and, based on the absorption rate, decided water addition ratio necessary for the reduction of unit quantity caused by the use of dry aggregate in designing concrete mixture, and analyzed the properties of unhardened concrete according to water addition ratio in manufacturing concrete using aggregate in the state of absolute dryness and in the state of surface dryness.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2037-2047
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• 1991

Strength is not simply a single given value but rather is a statistical one with certain distribution functions. This is because it is affected by many unknown factors such as size, shape, stress distribution, and combined stresses. In this study, a model of loss probability is proposed in view of the fact that one of the fundamental configuration of nature is hexagonal, for example, the shapes of lattice unit, grain, and so on. The model sues the concept of loss of certain element in place of Jayatilaka-Trustrum's length and angle of cracks. Using this model, the loss probability due to each loss of certain elements is obtained. Then, the maximum principal stress is calculated by the finite element method at the centroid of the elements under the tensile load for the 4,095 models of analysis. Finally, the failure probability of the brittle materials is obtained by multiplying the loss probability by the ratio of the maximum principal stress to theoretical tensile strength. Comparison of the result of the Jayatilaka-Trustrum's model and the proposed model shows that the failure probabilities by the two methods are in good agreement. Further, it is shown that the parametric relationship of semi-crack lengths for various degrees of birittleness can be determined. Therefore, the analysis of the failure probability suing the proposed model is shown to be promising as a new method for the study of the failure probability of birttle materials.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.2
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• pp.216-233
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• 2013

Conventional optimization designs of wireless networks mainly focus on spectral efficiency (SE) as a performance metric. However, as diverse media services are emerging, a green wireless network, which not only meets the quality of experience (QoE) requirements for users and also improves energy efficiency (EE), is the most appropriate solution. In this paper, we firstly propose the unit QoE per Watt, which is termed QoE efficiency (QEE), as a user-oriented metric to evaluate EE for wireless networks. We then analyze which is the kind of wireless resource given priority to use under different scenarios to obtain an acceptable QEE. Particularly, power, delay and data-rate related to QoE are separately addressed for several typical services, such as file download, video stream and web browsing services. Next, the fundamental tradeoffs are investigated between QEE and SE for wireless networks. Our analytical results are helpful for network design and optimization to strike a good balance between the users perceived QoE and energy consumption.

• School Mathematics
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• v.19 no.1
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• pp.117-135
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• 2017

Even though patterns and correspondence serve a fundamental basis of function for elementary students, there has been lack of research in this field. This study explored prior studies to extract the key instructional elements on how to teach patterns and correspondence. This study then analyzed the unit of 'patterns and correspondence' in the mathematics textbooks in terms of four key instructional elements (i.e., relation to real-life contexts, diversity of pattern tasks, exploration for a correspondence relationship, and teaching variables). The results of this study showed that topics dealing with patterns and correspondence were represented with relation to real-life contexts but diversity of pattern tasks and exploration for a correspondence relationship were needed to be further considered in the textbooks. Another noticeable result was that teaching variables was not explicitly addressed in the textbooks. Based on these results, this study provides textbook writers with implications on what to further consider in dealing with patterns and correspondence.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.1
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• pp.11-19
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• 2004

Such social structures as bridges,, buildings, dams and towers have been transformed by their own load or fundamental ground. They have been behaved by other external causes. These regular or irregular behaviors threaten to do their users safety. Therefore, to monitor the load of the structures or reaction shown by them could help to verify their behaviors. RTK GPS allows the use of a static base station and remote rover unit to allow f3r data collection within several seconds and in real time. It is useful for monitoring the behaviors of massive structures like bridges. In this Study, Among GPS methods, we used RTK GPS to analyze the precision of monitoring and then on the basis of it, we developed a monitoring system using RTK GPS when measured the behavior of main tower of a suspension bridge by using RTK GPS. Comparing a deviation between observation values, X axis was Imm, Y axis was 1mm and Z axis 2.2mm. It turned out that it was possible to monitor and measure structures by RTK GPS.