나선형 구조와 시간­역사의 모형에 관한 연구

정은영 한국기초조형학회 2010 기초조형학연구 Vol.11 No.2

Focusing on Vladimir Tatlin's Monument to the Third International (1919-20) and Robert Smithson's Spiral Jetty (1970), this paper explores the ways in which the two artists imagined the process of time and history via the shape of spiral. Tatlin, the founder of Russian Constructivism, realized his dictum, "real materials in real space," in the Monument to the Third International, which configured the organic, progressive history in the swirling spiral frame. The spiral was projected to contain an inner structure which would serve to actualize revolutionary life on an everyday level. The dynamic, swirling spiral embodied the Russian avant-garde's notion of revolutionary time, in which the passage of time and the revolutionary history would be organically integrated on a daily basis. Robert Smithson's Spiral Jetty implied a different, even contrasting, vision of time and history. Representative of site-specific Earthwork, Spiral Jetty incorporated the desolate, dystopian environment along the Great Salt Lake in Utah as a crucial component of the work. For Smithson, the spiral form provided a model of inorganic, non-progressive time and history, which was indebted both to the irreversible increase of entropy, the Second Law of Thermodynamics, and to the spiral growth of crystals. This paper suggests that the two different modes of visualizing time and history were in themselves conditioned by different historical situations. 본 논문은 블라디미르 타틀린의 <제 3 인터내셔널 기념비>(1919-20)와 로버트 스밋슨의 <나선형 방파제>(1970)에서 시간과 역사의 모형으로 사용된 나선형 구조를 집중분석한다. 러시아의 구축주의자 타틀린은 1915년 이후 “실제 공간에서 실제 재료를 사용하라”는 원칙하에 일상의 재료를 이용한 조각을 전시장의 코너에 위태롭게 설치함으로써 구체적인 공간성과 실제적인 시간성을 도입하였다. 특히 이 실제적인 시간성은 러시아 혁명을 정점으로 인간의 진보역사와 일상의 시간이 유기적으로 통일된 혁명적인 시간의식으로 발전한다. <제 3 인터네셔널 기념비>는 이러한 유기적인 시간-역사관을 역동적인 나선형 구조로 구체화한 기념비였다. 즉 역동적으로 치솟는 나선형의 프레임과 큐브, 피라미드, 실린더의 내부구조는 일상의 반복적인 시간과 거대한 진보의 역사가 하나로 통일된 혁명적인 시간의 모형이었다. 반면 후기자본주의와 주체의 탈중심화가 심화되기 시작하는 1970년대 미국의 대지미술가 스밋슨은 문명의 폐허를 연상시키는 유타 주의 그레이트 솔트 레이크에 디스토피아적인 <나선형 방파제>를 설치하였다. <방파제>의 나선형 패턴은 진보나 발전 개념이 배제된 비유기적인 시간-역사 개념을 구체화한 것으로, 열역학 제 2 법칙인 엔트로피의 증가원리와 결정체의 나선형 퇴적을 탐구하는 결정학의 영향을 받은 것이었다. 이와 같이 본 논문은 나선형이라는 동일한 패턴에 투사된 상반된 시간성과 역사의식을 구체적인 작품 속에서 분석하고, 조형예술과 시간성의 관계를 각각의 특수한 역사적 상황과 연결하여 숙고한다.

What makes firms issue death spirals? A control enhancing story

Woochan Kim,Woojin Kim,Hyung-Seok Kim 한국재무학회 2009 한국재무학회 학술대회 Vol.2009 No.08

This paper studies the motive of issuing floating-priced convertibles or warrants, known as death spirals, in a country where the private benefit of control is high. Using a total of 199 death spiral issuances by public firms listed in the Korea Stock Exchange during 1998-2006, we find a number of pieces of empirical evidence that are not consistent with the last-resort financing hypothesis, but rather consistent with the control enhancing or control transferring hypothesis. First, operating performance of death spiral issuers are not necessarily poor at the time of the issue nor do they deteriorate over time following the issue. Second, death spiral issuers that are more likely to be motivated by control enhancing or transferring purposes - firms with no subsequent changes in control - exhibit superior operating performance at the time the issue compared to other death spiral or non-death spiral issuers. Third, these firms do not experience a decrease in proportional ownership by the controlling party, while family members other than the controlling shareholder experience the most pronounced increases in the number of shares held. Fourth, in approximately half of these firms, at least one member of the controlling party holds hybrid securities that can be later converted into the firm’s voting shares.

What makes firms issue death spirals? A control enhancing story

Woochan Kim,Woojin Kim,Hyung-Seok Kim 한국재무학회 2008 한국재무학회 학술대회 Vol.2008 No.11

In this paper, we study the motive of issuing floating-priced convertibles or warrants, known as death spirals, in a country setting where the private benefit of control is high. Using a total of 199 death spiral issuances by public firms listed in the Korea Stock Exchange during 1998-2006, we find a number of empirical evidences that are not consistent with the last-resort financing hypothesis, but rather consistent with the control enhancing or control transferring hypothesis. First, death spirals are not necessarily issued by firms with poor operating performances. Second, death spiral issuers, where control is preserved within the family, experience an increase of ownership by affiliated firms. Third, this group of death spiral issuers tends to perform better than those in which family loses control.

맴돌이형 결함접지구조를 이용한 마이크로파 증폭기의 소형화 방법

임종식,정용채,안달,남상욱,Lim, Jong-Sik,Jeong, Yong-Chae,Ahn, Dal,Nam, Sang-Wook 한국전자파학회 2003 한국전자파학회논문지 Vol.14 No.9

맴돌이형 결함접지구조(spiral-shaped defected ground structure, Spiral-DGS)를 이용하여 증폭기의 크기를 줄이는 새로운 방법이 제시되었다. 접지면에 Spiral-DGS를 지니는 마이크로스트립 선로는 동일한 물리적 길이의 표준형 마이크로스트립 선로에 비하여 더 큰 전파지연상수와 전기적 길이를 갖는다. 또한 대역저지여파기와 같이 특정한 대역에서 우수한 차단 특성을 갖는다. 이 차단 대역이 증폭기의 하모닉을 차단하는데 사용된다. 입,출력 정합회로 내에서 Spiral-DGS가 삽입된 선로의 길이는 원래의 선로 길이의 39 %와 44 %에 불과하다. 그러나 소형화된 증폭기의 측정된 S-파라미터는 원증폭기의 S-파라미터와 잘 일치한다. 소형화된 증폭기의 측정된 2차 하모닉의 크기는 원증폭기보다 최소한 10 dB 이상 더 작다. 3차 하모닉 제거를 위한 Spiral-DGS가 같은 방법으로 증폭기 소형화에 적용되는데, 25 dB 이상의 3차 하모닉 차단 효과를 보인다. A new method to reduce the size of microwave amplifiers spiral-shaped defected ground structure(Spiral-DGS) is proposed. A microstrip line having Spiral-DGS on the ground plane produces increased slow-wave factor and electrical length for the fixed physical length. In addition, it provides an excellent rejection characteristic for a finite frequency band like band rejection filters. The rejection band is used for rejecting harmonic components of amplifiers. The reduced microstrip line lengths in matching networks by Spiral-DGS are 39 % and 44 % of the original ones in input and output matching networks, respectively. It is shown that the measured S-parameters of the reduced amplifier agree well with those of the original amplifier. The measured second harmonic of the reduced amplifier is much less than that of the original amplifier by at least 10 dB. The same technique is applied to reject the third harmonic using the proper Spiral-DGS for the third harmonic frequency. The measured third harmonic is smaller than that of the original amplifier by 25 dB.

Uniaxial behavior of circular ultra-high-performance fiber-reinforced concrete columns confined by spiral reinforcement

Shin, Hyun-Oh,Min, Kyung-Hwan,Mitchell, Denis Elsevier 2018 Construction & building materials Vol.168 No.-

<P><B>Abstract</B></P> <P>This paper presents results from the uniaxial tests of six large-scale ultra-high-performance fiber-reinforced concrete (UHPFRC) circular columns confined by spirals. The UHPFRC used in this study had 1.5% of hybrid micro-steel fibers (1.0% of 19.5 mm fibers and 0.5% of 16.3 mm fibers) in the mixture and had compressive strengths varying from 163 to 181 MPa. The effects of the volumetric ratio of spiral reinforcement, compressive strength of concrete, and presence of hybrid micro-steel fibers on the axial load responses, including post-peak deformability, were investigated. In addition, the ductility level reached by circular UHPFRC columns designed according to the minimum spiral reinforcement of current design provisions of the CSA A23.3-14 Standard and the ACI 318-14 Code were evaluated to investigate the applicability of these equations to UHPFRC columns. Test results showed that the combined effect of the minimum spiral reinforcement and steel fibers resulted in sufficient post-peak ductility of the UHPFRC columns. To investigate the efficiency of the shape of the confinement reinforcement, the test results of the circular UHPFRC columns confined by spirals were compared with those from equivalent-sized square UHPFRC columns confined by hoops. The test results demonstrate the superior performance of circular spirals for developing the ductile behavior of UHPFRC columns than the same volumetric ratio of rectilinear hoops. A design recommendation for spiral reinforcement that ensures the ductile behavior of UHPFRC columns in moderate seismic regions is proposed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Circular UHPFRC columns with varying spiral spacing and concrete strength were tested. </LI> <LI> Circular UHPFRC columns detailed with different code provisions were investigated. </LI> <LI> The efficiency of circular spirals and square hoops on confinement were compared. </LI> <LI> Steel fibers in UHPFRC allowed for gradual spalling and high damage tolerance. </LI> <LI> A design recommendation for spiral reinforcement in UHPFRC columns is proposed. </LI> </UL> </P>

Spiral tool paths for high-speed machining of 2D pockets with or without islands

Mikkel Abrahamsen 한국CDE학회 2019 Journal of computational design and engineering Vol.6 No.1

We describe new methods for the construction of spiral tool paths for high-speed machining. In the sim-plest case, our method takes a polygon as input and a number d > 0 and returns a spiral starting at a cen-tral point in the polygon, going around towards the boundary while morphing to the shape of the polygon. The spiral consists of linear segments and circular arcs, it is G1 continuous, it has no self-intersections, and the distance from each point on the spiral to each of the neighboring revolutions is at most d. Our method has the advantage over previously described methods that it is easily adjustable to the case where there is an island in the polygon to be avoided by the spiral. In that case, the spiral starts at the island and morphs the island to the outer boundary of the polygon. It is shown how to apply that method to make significantly shorter spirals in some polygons with no islands than what is obtained by conventional spiral tool paths. Finally, we show how to make a spiral in a polygon with multiple islands by connecting the islands into one island.

Evaluation of geometric factors influencing thermal performance of horizontal spiral-coil ground heat exchangers

Kim, Min-Jun,Lee, Seung-Rae,Yoon, Seok,Jeon, Jun-Seo Elsevier 2018 Applied thermal engineering Vol.144 No.-

<P><B>Abstract</B></P> <P>This study aims to estimate the thermal performance of a horizontal spiral-coil ground heat exchanger (GHE), focusing on the geometry factor of the spiral-coil. Prior to the thermal performance evaluation, an indoor thermal response test (TRT) was conducted with a 5 m x 1 m x 1 m steel box filled with dry Joomunjin sand and TRT equipment was used to validate the numerical analysis using the commercial program COMSOL Multiphysics 5.2a, which is based on computational fluid dynamics (CFD). Next, the number of analysis cases was set by selecting the key factors affecting the thermal performance of a horizontal GHE: installation depth, fluid velocity, thermal conductivity of the ground, and numerical studies were conducted on the 16 cases. As a result of the analysis, it was observed that the pitch does not affect thermal performance if the pitch exceeds 0.6 m. These same results were derived even when additional changes in the key factors were taken into consideration. In addition, it was revealed that the spiral diameter does not affect the thermal performance of the horizontal spiral-coil GHE. Therefore, we concluded that the geometric factor that determines the optimal thermal performance of the horizontal spiral-coil GHE is not the spiral diameter but the pitch, and the 0.6 m pitch of the horizontal spiral-coil GHE can provide a compromise between the thermal performance and installation land space.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermal performance evaluation of a horizontal spiral-coil GHE was conducted. </LI> <LI> A laboratory thermal response test on the horizontal spiral-coil GHE was performed to validate the numerical model. </LI> <LI> The numerical modeling were in good agreement with the experimental results. </LI> <LI> The optimal specification in terms of thermal performance was suggested. </LI> </UL> </P>

Spiral-shaped SU-8 cantilevers for monitoring mechanical response of cardiomyocytes treated with cardiac drugs

Dai, Y.,Oyunbaatar, N.-E.,Lee, B.-K.,Kim, E.-S.,Lee, D.-W. Elsevier 2018 Sensors and actuators. B Chemical Vol.255 No.3

<P><B>Abstract</B></P> <P>In this paper, a spiral-shaped SU-8 cantilever with biocompatibility was proposed to monitor the changes of cardiac contraction in response to injection of drug in real time. The cantilever comprises a thick quadrate body and a filmy spiral cantilever with micro-grooves and gold patterns on the top of its surface. The longitudinally patterned micro-grooves facilitate the aligned growth of cardiomyocytes in order to increase the contraction force. In addition, the spiral shape increases the cantilever’s effective length and decreases its spring constant, which means its bending displacement can be increased for the same force as compared to that observed in a conventional rectangular cantilever. The bending displacement of the spiral SU-8 cantilever induced by the contraction of cardiomyocytes can be precisely measured at the nanoscale using a homemade laser-based measurement system. The displacement in the spiral SU-8 cantilever without micro-grooves was much greater than that in the case of traditional rectangular SU-8 cantilevers. The displacement produced by the spiral cantilever with grooves is 240% greater than that without grooves. Following preliminary experiments, cardiac drugs including Verapamil, Quinidine, Lidocaine, E-4031, and Bay K 8644 were used to evaluate their side effects on cardiomyocytes. Quantitative analysis of measurements shows that not only Verapamil and Quinidine but also Lidocaine and E-4031 treatment can decrease the cell beating frequency, and both the Verapamil and Lidocaine treatment can decrease the cell contraction force. Furthermore, Bay K 8644 assay results indicate that it can decrease the contraction force and increase the beating frequency of cardiomyocytes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spiral cantilever integrated with micro-grooves is proposed for a real time monitoring of cardiac contractibility. </LI> <LI> Home-made measurement system is developed to precisely measure the contractibility of cardiomyocytes at the nanoscale. </LI> <LI> Five different kind of drugs have been employed for the preliminary study of drug-induced cardiac toxicity. </LI> <LI> Spiral cantilever arrays are expected to be applied as a new method to support for the drawbacks of conventional methods. </LI> </UL> </P>

현대 유리 예술에 있어서 원시모양(原始模樣)의 새로운 적용 형태에 관한 연구

김혜영(Kim Hye Young) 한국조형디자인학회 2005 조형디자인연구 Vol.8 No.2

Hwnankind has been producing vanous glass works for more than five thousand years. Despite such a long history of using glasses in daily life, it was only after the 196Os that glass began to be recognized as a valuable material for artworks. However, glass works are first associated with 'technology', and many glass works are actually considered to be technological products. Glasses, however, transcend technological aspects in terms of its variability as a valuable art material. Thus, in order for glasses to position itself as a mainstream material of art successfully, a new notion of artistic world based on the glass should be established. This study aims at pursuing unity between space and glasses through glass- space artworks. The spiral shapes of glass works that are made using the blowing technique are innovated into new forms for arts works to be installed in a space with the spiral form as a motive. In order to do that, this study first inquires into the symbolism of the spiral shapes by looking into various myths and legends associated with the form in every part of the world. The study then compares and contrasts the modem glass works of modem art based on research of various theories. What it ultimately aims to achieve is to suggesting and interpreting the potential of various forms of glass art. The actual stage of producing glass works for this study will be an opportunity to inquire into the human psychology and ideas and visualize them in modem sense by analyzing and studying the spiral forms of art works. This study intends to form a new world of art, with the spiral form, glass, and space as the three main subjects. In other words, it intends to define what glass can be for the art of space, viz. the art of space-glass(Glass Space Art). This study thereby aims to provide new directions and potentials for modem glass art and exhibit the new glass works produced on the basis of the study. This study is mainly composed of the actual production of glass works, and an essay is to provide supplementary information. The essay aims to explain the production of the works in more depth.

2P-210 Fabrication of Chiral Nanostructure by Directed Self-Assembly

최홍균,장재범,( Caroline Ross ) 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

In this study, we demonstrate that confinement of a cylindricalmorphology BCP in a shallow circular pit can produce either concentric rings or a spiral. A spiral is promoted by the presence of a notch-shaped feature within the template which controls the spiral chirality. The length of the spiral increases with the diameter of the template. Design of the notch geometry enabled double spirals to be formed. A notch of width □ L0 promotes spirals even for commensurate pit sizes indicating the critical importance of the inner shape of the template. For smaller notches, spirals formed for incommensurate template diameters and rings for commensurate template diameters. Analogous to using a notch to initiate a spiral in a circular pit, our approach could be extended to guide the chirality of 3D helical spirals formed in cylindrical confinements with a helical ramp template.