• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.705-707
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• 2004

In this paper, we propose a robust control technique against parameter uncertainties as well as external disturbances. It is robust control scheme using discrete-time state space disturbance observer. It does not require disturbance modeling, plant inverse modeling and/or Q filter. In frequency domain, its performance is evaluated in terms of sensitivity and complementary sensitivity as well as gain and phase margin. Finally we discuss design criterion of state space disturbance observer considering its performance in frequency domain.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.297-308
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• 2022

Most air-breathing aircraft operated in the hypersonic region are equipped with a scramjet engine. In a scramjet engine, a shock wave generated at an inlet acts as a compressor for a general gas turbine engine instead, so total pressure loss caused by the shock wave is considered very important. In this study, to minimize total pressure loss, a method of designing an external compression inlet using isentropic compression surface was proposed, and an external compression inlet with 3-deflection angles and Busemann inlet were designed under the same conditions. After that, through computational analysis, the performance characteristics at off-design conditions were compared. Each inlet shape was truncated according to the length of the 3-ramp external compression inlet, and the boundary layer correction was performed. The isentropic external compression inlet showed superior performance at the design point, but under the off-design conditions, its performance was degraded compared to the 3-ramp external compression inlet.

• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.107-113
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• 2019

The highest percentage of single-person households is older than 60. Many of them live in dilapidated residential space because they are in difficult economic situations. The windows of them often don't exist or don't function properly as windows. As a result, they are suffering from social problems such as depression, solitude. This paper proposes an interactive window interface that reflects external environmental information for older people in their 60s or older of one household living in a dilapidated residential space. This content utilizes an inexpensive TV or PC monitor that doesn't require extra space and cost. Recognizing a user's hand through intuitive touch-sensing technology, which doesn't require much help from older people, this content provides weather videos and temperature information that reflect current external environment. Alert notification sound and SMS service are provided in preparation for more critical user emergencies. This content enables users to feel emotional stability and respond quickly to emergencies.

• Journal of the Korean Institute of Rural Architecture
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• v.24 no.4
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• pp.9-16
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• 2022

The purpose of this study is to analyze the cross-sectional ratio of the courtyard, an external space that not only was used as a workplace, shelter, and playground in our lives, but also gave symbolic meaning to Koreans. Since the beginning of 2000, Hanok began to receive rapid attention from people, and Hanok construction and remodeling were actively carried out in urban and rural areas. In particular, Bukchon and Seochon in Seoul, around Cheonmachong in Gyeongju, and Hanok Village in Jeonju became popular places related to hanok, and Gyeongju, Buyeo, Gongju, and Iksan were designated as ancient districts to encourage the construction of hanok. However, although hanok is being built with national trends, support, and interest, attention is focused only on the external form, materials, and convenience of use, and the composition and system of the external space have not been properly reviewed. Therefore, this study aims to understand the functions and meanings of the yard in traditional housing, and to analyze the proportion of the height of the building surrounding the yard and the depth of the yard in terms of closure and opening. In addition, the system and characteristics of the external space of traditional architecture felt by this can be used as basic data in designing traditional architecture.

• Steel and Composite Structures
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• v.46 no.2
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• pp.211-220
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• 2023

Welded hollow spherical joints are commonly used joints in space grid structures. An internal stiffener is generally adopted to strengthen the joints when large hollow spheres are used. To further strengthen it, external stiffeners can be used at the same time. In this study, axial compression tests are conducted on four full-scale 550 mm spherical joints. The failure modes and strengths of the tested joints are investigated. It shows that the external stiffeners are able to increase the strength of the joint up to 25%. A numerical model for large spherical joints with stiffeners is established and verified against the experimental results. Parametric studies are executed considering six main design factors using the verified model. It is found that the strength of the spherical joint increases as the thickness, height and number of the external stiffeners increase, and the hollow sphere's diameter has a neglectable effect on the enhancement caused by the external stiffeners. Based on the experimental and numerical results, a practical formula for the compressive bearing capacity of large welded hollow spherical joints with both internal and external stiffeners is proposed. The proposed formula gives a conservative prediction on the compressive capacity of large welded hollow spherical joints with both internal and external stiffeners.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.85-90
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• 2005

• Korean Institute of Interior Design Journal
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• v.19 no.1
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• pp.46-54
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• 2010

Since the accomplishment of industrialization and mechanization, human and the nature have gone farther their own way. Human depending on technology have been increasingly expanding and developing their artificial space and as times go by in such a way, estrangement between the human and nature has resulted in dissatisfaction of human's instinctual desire and devastation of human's living. People, to deal with such challenge, begins taking a look at the nature. In introducing the nature into the modern architecture, a physical natural element is often directly taken into or the shape that could be inferred from the nature is taken. The study was intended to identify the characteristics of the pattern introducing the nature into the modern architecture, as mentioned in the former case, which is summarized as follows, Introduction of the nature contains a variety of functions in the space and it creates the new space by integrating the internal and external space which becomes boundaryless integrated space. The boundary in the building tends to be getting more ambiguous, while the space accommodating the nature serves the interface, playing a role of intermediator for both the internal and external space. It functions the open public place that helps build the natural community among the users but taking the nature into the inner space, and it is used to attempt to change the interior of the building or for ventilation lighting or energy-saving purpose. The spatial meaning was found to have varied depending on pattern of the nature introduced. Such conclusions mentioned hereon is expected to help forecast and understand the forthcoming space accommodating the nature when reviewing the pattern of introducing the nature appeared In modern architecture.

• Korean Institute of Interior Design Journal
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• v.23 no.4
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• pp.83-93
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• 2014

Because the 'image' is the 'reality' in this era, there are the characteristics dematerialized between reality and non-reality in the contemporary architecture. These are promoting individualization, differentiation and multi-layered time with the development of electronic technology. This trend emphasizes the importance of imagines that are not only homogenized, simultaneous but also overlapped, multi-layered, discriminatory. Perspectives and essential characteristics of the architectural skin are changing in terms of the technical and social awareness and that means the skin has features as a complex body. Recently as an imagine creator, the architectural skin make form of media boundaries reflecting the various relationships between the observer and the external environment and also, the interior space become another sensory skin by removing the boundaries of the internal and external. It is important that making an identity of the architecture defined by the media or the imagine as well as the importance of space in architecture. These changes of skin make the third space based on the viewer's imagination and show the potential of new architectural skin with the expansion space by blurring the boundary between reality and illusion. It occurs to the diversity of the architectural skin with the identity. It will more diversified and be recognized immediately and sensibly through the interface attributes in contact with the city directly. In addition, it is more important that the skin become a unified body related with urban, social and cultural context.

• Korean Institute of Interior Design Journal
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• v.22 no.2
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• pp.186-193
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• 2013

In the commercial space, the modern consumers want to consume not only product but also culture. Thus, the modern commercial space tries to induce the customer's concern and purchase to the differentiated design. The introduction of this 'the natural element' delivers the pleasure and stability to the consumer buying process and availability is enlarged. Therefore, the purpose of study is gain that expression and characteristic method of the natural element in the commercial space. The detailed study method are as follows. First, the study looks into the natural element expression tendency in the modern space. Second, the expression type of the natural element was classified as 'Reappearance', 'Transformation', and 'Fuse' based on the preceding research. And according to the content of the expression type, subdivided method of 'Inclusion' and 'Replication' of 'Reappearance' and method of 'Imitation' and 'Association' of 'Transformation' and method of 'Juxtaposition' and 'Combine' of 'Fuse'. Third, the result of analyze the characteristic of expression of the natural element of the besides the commercial space case 20 place is as follows. First, 'Inclusion' of 'Reappearance' introduced the external scenery or planned garden as the inside through the opening. 'Replication' is used for decorative purposes or functional purposes as the natural element. 'Imitation' of 'Transformation' imitated the form, pattern, and color of the natural element and was mainly expressed in the wall and objet. The method of 'Association' expressed the concept of the natural element for the whole of the space and a portion of the wall and objet repetitively. As for 'Juxtaposition', mixture of 'Reappearance' had a good visual effect, because it can be obtained the external-internal nature. As for 'Combine', mixture of 'Replication' and 'Imitation' was the most common method. Thus, the study results are expected to be utilized as base date in designing the commercial with development of the natural element application method.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.653-664
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• 2015

When the structural analysis is performed for the concrete lining of the water pressure tunnel, many parameters are considered such as relaxed ground loads, internal water pressure, external water pressure, the shrinkage of the concrete lining, grouting pressure, etc. But, there are no standards and manuals for the structural analysis for the concrete lining of the water pressure tunnel. Above all, the external water pressure has an much effect on the stability of tunnel. So, in case that permeability of ground is large, the external water pressure should be decreased by installation of weep hole, or reinforced ground by ground improvement grouting should be pressed by the external water pressure instead. But, when weep hole is installed to reduce the external water pressure, the many problems may me occurred. Thus, reasonable approach for treatment of the external water pressure is necessary if weep hole is not installed. Therefore, the purpose of this study is to analyze design cases and studies for treatment of the external water pressure in performing structural analysis for the concrete lining of the water pressure tunnel, and to find reasonable method for tunnel lining modeling which is the treatment of the external water pressure according to permeability of ground and consequently the design of ground improvement grouting.