• Korean Journal of Mathematics
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• 제20권2호
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• pp.161-176
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• 2012

The authors [6] introduced the concept of a complete matrix of grade $g$ > 3 to describe a structure theorem for complete intersections of grade $g$ > 3. We show that a complete matrix can be used to construct the Eagon-Northcott complex [7]. Moreover, we prove that it is the minimal free resolution $\mathbb{F}$ of a class of determinantal ideals of $n{\times}(n+2)$ matrices $X=(x_{ij})$ such that entries of each row of $X=(x_{ij})$ form a regular sequence and the second differential map of $\mathbb{F}$ is a matrix $f$ defined by the complete matrices of grade $n+2$.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권9호
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• pp.3401-3420
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• 2021

We provide a traceable ciphertext-policy attribute based encryption (CP-ABE) construction for monotone access structures (MAS) based on composite order bilinear groups, which is secure adaptively under the standard model. We construct this scheme by making use of an "encoding technique" which represents the MAS by their minimal sets to encrypt the messages. To date, for all traceable CP-ABE schemes, their encryption costs grow linearly with the MAS size, the decryption costs grow linearly with the qualified rows in the span programs. However, in our traceable CP-ABE, the ciphertext is linear with the minimal sets, and decryption needs merely three bilinear pairing computations and two exponent computations, which improves the efficiency extremely and has constant decryption. At last, the detailed security and traceability proof is given.

• East Asian mathematical journal
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• 제40권1호
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• pp.75-83
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• 2024

For a reduced, irreducible and nondegenerate curve C ⊂ ℙ^r of degree d, it was shown that the arithmetic genus g of C has an upper bound π₀(d, r) by G. Castelnuovo. And he also classified the curves that attain the extremal value. These curves are arithmetically Cohen-Macaulay and contained in a surface of minimal degree. In this paper, we investigate the arithmetic genus of curves lie on a surface of minimal degree - the Veronese surface, smooth rational normal surface scrolls and singular rational normal surface scrolls. We also provide a construction of curves on singular rational normal surface scroll S(0, 2) ⊂ ℙ³ which attain the maximal arithmetic genus.

• 한국실내디자인학회논문집
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• 제15권5호
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• pp.68-76
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• 2006

Frei Otto, who is called to be the father of the ecological architecture, has shaped a peculiar architectural form style. In distance from the formalistic persistence to the modernist form canon and the postmodern tendencies to the self-representation of architects, Frei Otto has taken a more fundamentalistic position. Through the interdisciplinary researches on the self-organizing processes in the nature and the technical world Frei Otto could reason with architects, engineers, biologists, historians and philosophers the principle and structure of the natural construction that is applicable to the morphological research and the architectural construction research. In the middle of his architectural and scientific works is the idea of 'the natural construction' situated, and the basic principle and instrument of this 'Die Prinzip der Selbstbildung, The Principle of Self-making'. Founding himself on this principle, Frei Otto seeks after the new architectural form that is light, natural, flexible and variable by reasoning the typical formation process which refers to the common denominator of the self-making processes in the nature, the technique and the architecture. Despite his architecture is to be called to the anonymous, his architectural vision is headed toward the rationalistic form in accord with the natural laws. This study is purposed to elucidate the constellation to which his scientific attempts belong and the theoretical and methodological foundations of his architecture of 'the natural construction'.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.359-365
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• 2008

As housing supply ratio has become over 100%, the strategic vision of government's policies has been changed from new construction to maintenance and regeneration of old architectural-structures. This fact has brought a light on the reconstruction and remodeling industries and a need for retrofit and rehabilitation techniques of existing foundation. Various methods of foundation for architectural-structures do exist. Among them, micropiling technologies are increasingly applied in foundation rehabilitation and seismic retrofitting projects. Micropiling techniques provide environmental-friendly methods for minimizing disturbance to adjacent structures, ground, and the environment. The installation is possible in restrictive area and general ground conditions. The fact that the installation procedures cause minimal vibration and noise and require very low ceiling height makes the micropiling methods to be commonly used for underpin existing structures. Specialized drilling equipment is often required to install the micropiles for existing basement facilities. This paper presents a case study in which micropiles were constructed to support a superstructure for vertical extension of existing elevator core and provide accessibility to underground parking lot. It is intended to become useful reference for the similar remodeling project.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.571-578
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• 2009

Recently, micropiling techniques are increasingly applied in foundation rehabilitation/underpinning and seismic retrofitting projects where working space provides the limited access for conventional piling methods. Micropiling techniques provide environmental-friendly methods for minimizing disturbance to adjacent structures, ground, and the environment. Its installation is possible in restrictive area and general ground conditions. The cardinal features that the installation procedures cause minimal vibration and noise and require very low ceiling height make the micropiling methods to be commonly used for underpin existing structures. In the design point of view, the current practice obligates the bearing capacity of micropile to be obtained from skin friction of only rock-socketing area, in which it implies the frictional resistance of upper soil layer is ignored in the design process. In this paper, a new micropiling method and its verification studies via field installation are presented. The new method provides a specific way to grout bore-hole to increase frictional resistance between surrounding soil and pile-structure and it allows to consider the skin friction of micropiles for upper soil layer during design process.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.123-124
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• 2023

Despite the acuuracy, stability, and economic feasibility of geomagnetic field-based indoor positioning, its applicability in construction sites needs to be thoroughly discussed due to the issue of distortion of geomagnetic fields around ferromagnetic objects such as rebars. In this study, the possibility of applying the geomagnetic field-based indoor positioning in construction sites was reviewed through the Student's t-test after measuring the changes in geomagnetic field values depending on the presence or absence of rebars. The statistical analysis revealed that there is a high probability (over 80%) of significant changes in geomagnetic field values when measuring points are located within 60cm from the rebars. On the other hand, the probability of minimal changes in geomagnetic field values is over 90% when measuring points are located more than 60cm from the rebars. This suggests the application of geomagnetic-based indoor positioning in construction sites would be possible if the issue of distortion in geomagnetic field values near rebars within 60cm is resolved.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.671-679
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• 2010

The construction of concrete track for the first time in Korea gives lots of meanings to civil engineering in various aspects. Settlement level needs to be kept minimal for the safety of the track. Concrete track has different structural characteristics comparing to conventional ballast track, so load distribution in concrete track is also different. Since it is the first time to build concrete track, there are very few experience and data available on the subject. Therefore it is important to evaluate how much load is transferred to the ground due to the running vehicle in concrete track and to determine the optimal thickness of layers. In this research, 9 individual earth pressure cells were installed at OOOk930 site in 2nd stage of Kyungbu high speed railway during under construction. The in-situ pressure data were measured at each layers during pump-car and locomotive were moving on the high speed railway surface.

• Structural Engineering and Mechanics
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• 제17권2호
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• pp.245-266
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• 2004

Incremental launching method is one of the highly competitive techniques for construction of concrete bridges. It avoids costly and time consuming form work and centralizes all construction activities in a small casting yard, thus saving in cost and time against conventional bridge construction. From the quality point of view, it eliminates the uncertainty of monolithic behaviour by allowing high repetitiveness and industrial environment. But, from analysis and design point of view, the most characteristic aspect of incrementally launched bridges is that, it has to absorb the stresses associated with the temporary supports that are gradually taken on by the deck during its launch. So, it is necessary to analyse the structure for each step of launching which is a tedious and time consuming process. Effect of support settlements or temperature variation makes the problem more complex. By using transfer matrix method, this problem can be handled efficiently with minimal computational effort. This paper gives insight into method of analysis, formulation for optimization of the structural system, effect of support settlement and temperature gradient, during construction, on the stress state of incrementally launched bridges.

• 한국건설관리학회논문집
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• 제14권3호
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• pp.123-133
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• 2013

지구온난화 문제에 대한 대책으로 녹색 사업에 대한 관심과 투자가 높아지고 있다. 국내 건설 기업들도 기존 토목 및 건축 공종에서 신재생에너지 사업으로 영역을 확대해 나가고자 한다. 그러나 신재생에너지 사업은 투자경제성이 검증되지 않고 건설 기업들은 관련 리스크에 대해 명확히 인지하지 못하고 있다. 본 연구에서는 녹색 건설 사업의 일환으로 국내에서 수행되고 청정개발체제(CDM)사업으로 등록된 신재생에너지 사업의 투자경제성에 관한 단계별 분석을 수행하였다. 1단계에서는 UNFCCC에 등록된 국내 CDM 사업을 대상으로 분석을 수행하였으며, 그 결과 평균 IRR은 -3.19%로 사업들의 수익성이 저조한 것을 파악하였다. 2단계에서는 사업별(태양광, 풍력, 수력, 매립가스)로 IRR이 가장 낮은 사업을 선정하여 국내의 발전차액지원제도(FiT)와 탄소배출권(CER)판매를 통한 추가 수입을 적용하여 수익성 향상 여부를 정량적으로 분석하였다. 그 결과 투자경제성이 있는 사업은 매립 가스 및 풍력 사업이었으며 두 보조방안에도 불구하고 태양광 및 수력 사업은 수익성이 없었다. 또한 사업별로 보조방안의 비중이 상이한 것을 볼 수 있었는데 특히 FiT는 태양광, CER판매는 매립가스 사업이 가장 혜택을 보았다. 이에 비해 풍력 및 수력 사업은 보조방안으로 인한 추가 수입이 적은 것을 파악하였다. 4개의 대상 사업 중 매립가스의 IRR이 가장 개선되었으나 풍력사업이 NPV가 가장 높고 보조방안에 대한 의존도가 낮아 투자매력도가 좋은 사업으로 드러났다. 건설 기업들은 신재생에너지 관련 기술이 성숙하면서 경쟁력이 높아짐에 따라 장기적 관점에서 관련 사업에 투자와 경험을 구축하는 것이 중요할 것으로 판단된다.